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Effects of Hemp (Cannabis sativa L.) Seed Oil Press-Cake and Decaffeinated Green Tea Leaves (Camellia sinensis) on Functional Characteristics of Gluten-Free Crackers Olga Radoˇcaj, Etelka Dimi´c, and Rong Tsao
Abstract: A mixture, simplex centroid, 2 components experimental design was used to evaluate the addition of hemp seed oil press-cake and decaffeinated green tea leaves, as functional ingredients to assess nutritional characteristics and antioxidant properties of gluten-free crackers. All samples with added hemp flour had much better nutritional qualities than the brown rice flour crackers in terms of higher protein, crude fibers, minerals, and essential fatty acids content. Likewise, all samples with added decaffeinated green tea leaves had much better antioxidant properties than crackers with no added green tea leaves. All crackers with added hemp flour had a significantly increased fiber content (39% to 249%) and decreased carbohydrate content (8.4% to 42.3%), compared to the brown rice flour crackers. All samples had antioxidant properties, even without the addition of green tea leaves. Optimization of the responses was conducted based on the maximized values for protein, fibers, omega-3 fatty acids content, as well as for the antioxidant activity and overall score. The suggested values for the addition of the hemp oil press-cake was 20% (total flour weight) with 4 g of decaffeinated green tea leaves that would provide protein content of 14.1 g/100 g; fibers content of 8.4 g/100 g; omega-3 fatty acids content of 3.2 g/100 g; antioxidant activity measured via 2,2-diphenyl-1-picrylhydrazyl value of 30.3 μmol TE/g d.w.; and an overall score of 8.9. This formulation has demonstrated potential application in the baking industry and marketing of these gluten-free crackers as a value-added functional product. Keywords: crackers, functional food, gluten-free, green tea leaves, hemp
Hemp seed oil press-cake as a by-product of cold-pressed oil processing and brown rice flour were used to design a functional gluten-free snack-type product—savory crackers. All crackers were high in minerals, fibers, and omega-3 fatty acids with a desirable omega-6/omega-3 fatty acids ratio. Green tea leaves were added to improve antioxidant activity, which greatly contributed to their functional properties. This qualified the crackers as a healthy snack with a minimal content saturated fatty acids and an abundance of polyunsaturated and monounsaturated fatty acids that originated from chia seeds residual oil present in the hemp flour.
Practical Application:
Introduction The term “celiac,” originates from the Greek word “koiliakos,” meaning “suffering in the bowel.” Coeliac disease (CD) is a common, chronic inflammatory malabsorptive disorder of the small intestinal mucosa, characterized by an improper immune response to ingested wheat gluten (composed of gliadin and glutenin) and related cereal proteins in genetically predisposed individuals, resulting in villous atrophy, crypt hyperplasia, and lymphocytic infiltration in the small intestine. Elimination of the immunogenic proteins from diet leads to clinical and histological improvement. Modern serological screening, followed by small intestinal biopsy, has revealed that CD is one of the most prevalent food (around 1% of the general population) intolerances worldwide and can occur at any age (Alaedini and Green 2008; Gainer 2011; Rivera and
MS 20131497 Submitted 10/20/2013, Accepted 12/29/2013. Authors Radoˇcaj and Dimi´c are with Faculty of Technology, Univ. of Novi Sad, Bulevar cara Lazara 1, 21000, Novi Sad, Serbia. Author Tsao is with Guelph Food Research Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, Ontario, N1G 5C9, Canada. Direct inquiries to author Radoˇcaj (E-mail: [email protected]).
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others 2013). Therefore, a development of gluten-free food with functional properties, especially to replace wheat proteins, fibers, and minerals, is very important in order to provide not only better selection, but also more nutritious food to the consumers that belong to this segment of population. The global market for functional foods was projected to exceed U.S. $243 billion by 2015, the U.S.A., Europe, and Japan being the dominant regions with a combined share of more than 85% (Sheiber 2012). The emergence of a new market segment called “Health and Wellness” reached a global value of U.S. $625 billion in 2012 (Khan and others 2013). Definitions, as well as regulatory requirements of functional foods, vary from country to country (Doyon and Labrecque 2008; Malla and others 2013). Canada defines functional food as a food similar in appearance to, or may be, a conventional food that is consumed as part of a usual diet, and is demonstrated to have physiological benefits and/or reduce the risk of chronic disease beyond basic nutritional functions, that is, they contain a bioactive compound. A nutraceutical is a product isolated or purified from foods that is generally sold in medicinal forms not usually associated with foods. A nutraceutical is demonstrated to have a physiological benefit or provide R C 2014 Institute of Food Technologists
doi: 10.1111/1750-3841.12370 Further reproduction without permission is prohibited
Hemp flour crackers with green tea . . . Table 1–Proximate analysis with tocopherols, minerals, and vitamins profile of hemp oil press-cake, brown rice flour, and chia seeds. Analysis (g/100 g)
Hemp oil-press Brown rice cake flour flour
Moisture Ash Fat Protein Crude fibers Carbohydrates (by difference) Tocopherols (mg/kg) α β+γ δ Minerals (mg/kg) Ca Cu Fe Mg Mn K Na Zn Vitamins (mg/100 g) Vit A Folic acid Riboflavin Pyridoxine
6.35 ± 0.07c
5.24 ± 0.09a 9.53 ± 0.12b 32.21 ± 0.17a 43.87 ± 0.05a 2.80 ± 0.35b 0.0 ± 0.0b 12.1 ± 0.0b 0.0 ± 0.0b
Chia seeds
9.87 ± 0.10a
8.19 ± 0.32b 1.44 ± 0.01c 3.84 ± 0.17b 2.72 ± 0.10c 32.83 ± 0.48a 6.91 ± 0.21c 20.72 ± 0.10b 2.26 ± 0.18c 33.18 ± 0.11b 76.80 ± 0.44a 1.24 ± 0.15c 1.61 ± 0.1a 5.32 ± 0.1c 0.51 ± 0.1a
0.0 ± 0.0b 67.6 ± 0.3a 0.0 ± 0.0b
20.6 ± 0.6c 533.1 ± 12.9a 120.3 ± 2.8b 0.1 ± 0.0.0a 0.1 ± 0.0.0a 0.1 ± 0.0.0a 6.6 ± 0.0.1a 0.6 ± 0.0.0c 4.3 ± 0.0.1b 173.5 ± 3.7b 102.6 ± 0.5c 331.6 ± 6.7a 7.8 ± 0.1b 1.5 ± 0.0c 14.2 ± 0.2a 432.3 ± 3.5b 199.1 ± 4.5c 671.9 ± 11.5a 15.2 ± 0.2b 19.0 ± 0.1a 3.4 ± 0.1c 2.4 ± 0.1b 1.8 ± 0.1c 2.3 ± 0.1a 1.00 ± 0.0a 0.0 ± 0.0b 2.6 ± 0.1a 0.0 ± 0.0b
0.0 ± 0.0b 2.6 ± 0.1a 1.5 ± 0.0a 4.1 ± 0.1a
0.0 ± 0.0b 0.0 ± 0.0b 2.6 ± 0.1a 0.0 ± 0.0b
Values are means ± SD; n = 3. Means in the same row followed by different superscript letters are significantly different (P < 0.05).
rheology of gluten-free dough based on chestnut flour due to the mucilage fibers that form viscous-gel-type systems (Moreira and others 2013). Crackers are defined as thin, hard-baked, crisp wafers or biscuits, usually made of unsweetened and unleavened dough using soft wheat flour. In the production of gluten-free crackers, additional ingredients must be used to compensate for a lack of wheat gluten (Han and others 2010). This is the primary reason we added hydrated chia seeds to improve the texture of the crackers’ dough. To the best of our knowledge, no data have been reported yet on the utilization of hemp oil press-cake flour and decaffeinated green tea leaves as functional ingredients, with regard to its nutritional and functional properties, for the preparation of gluten-free crackers. Therefore, our results were compared with gluten-free crackers made using different flours. Savory-type crackers with hemp flour have been chosen to blend the green tea leaves with green colored hemp flour providing a convenient, functional snack-type food. The objectives of this study were: (1) to investigate a possible use for hemp oil press-cake in the gluten-free crackers, (2) to evaluate the effects of the hemp flour primarily on the changes in chemical characteristics of crackers, such as contents of omega-3 and omega-6 fatty acids, proteins, fibers, and minerals content of the samples, (3) to investigate the effect of decaffeinated green tea leaves as an antioxidant in the gluten-free crackers, and (4) to determine the optimum amount of hemp flour, as a replacement for brown rice flour, which would deliver maximum nutritional benefits, as well as the optimum amount of green tea leaves, which would deliver maximum antioxidant properties for gluten-free crackers that will be acceptable by the sensory panel. Vol. 79, Nr. 3, 2014 r Journal of Food Science C319
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protection against chronic disease (Agriculture and Agri-Food Canada 2013). The number of discrete functional food ingredients is increasing, and functional foods are widely used in many everyday food products (Griffiths and others 2009). Functional foods have been developed in virtually all food categories. These products have mainly been launched in the dairy, confectionary, soft drinks, bakery, and baby-food markets (Siro and others 2008). One of the examples often quoted within the functional food sector is the introduction of margarine spreads fortified with plant sterols (Henry 2010). Among other functional foods, bakery products were also investigated as gluten-free options: almond- and peanutflour-based cookies fortified with iron (Granato and Ellendersen 2009); raw and popped amaranth-flour-based breads and cookies rich in protein (de la Barca and others 2010); protein and crude fibers enriched biscuits based on plantain and chickpeas flours (Yadav and others 2012). However, research in Europe has shown that there is a confusion among consumers about functional foods and they need to be informed to understand the exact benefits of such food in order to purchase it (Blades 2000; Annunziata and Vecchio 2011). The use of by-products of the food processing industry as a source of functional ingredients such as antioxidants, tocopherols, carotenoids, phenols, fibers, proteins, and so on, is on the rise. Potential high-volume by-products of the food industry are fruits and vegetables (Schieber and others 2001) and cold- pressed seed oil cakes (flours) such as camelina (Terpinc and others 2012); pumpkin, parsley, mullein, cardamom, milk thistle (Parry and others 2008); flax (Ogunronbi and others 2011); grape seed flour (Ozvural and Vural 2011); and sesame seed oil cake (Nascimento and others 2012), to name a few. For example, a hull-less pumpkin oil press-cake was recently used to develop a spread rich in omega-3 and omega-6 fatty acids, minerals, and proteins (Radoˇcaj and others 2012). Hemp seeds, which contain a low level (0.3%) of tetrahydrocannabinol (THC), are legally grown in Europe and Canada and are of high nutritional value. Oil press-cake, as a by-product of the cold-pressing hemp oil process, is rich in proteins, fibers, phytochemicals, minerals, linoleic (omega-6), and alpha-linolenic (omega-3) essential fatty acids, as well as gamma-tocopherols. Two main proteins in hemp seeds are edistin and albumin. These have high amounts of essential amino acids and are exceptionally high in amino acid arginine. Hempseed proteins are comparable to the egg white and soy protein (Callaway 2004). Defatted hemp flour was used in the past for the fortification of energy bars (Norajit and others 2011). Green tea is made by steaming or frying fresh tea leaves at elevated temperatures to prevent enzymatic oxidation. It contains polyphenols, which include flavanols (catechins), flavandiols, flavonoids, and phenolic acids (Chow and Hakim 2011). Tea catechins have been shown to have health benefits including cancer prevention of many types (Cabrera and others 2006), decreasing LDL cholesterol level (Kim and others 2011), and antiobesity effects (Cardoso and others 2013). Green tea extract was used to stabilize the lipid oxidation rate of omega-3 oils incorporated into table spreads (O’Dwyer and others 2012). Chia seeds are high in proteins, fibers, minerals, and highly unsaturated fatty acids such as alpha-linolenic (approximately 60%) omega-3 essential fatty acid and have been used in the prevention and treatment of coronary artery disease, hypertension, diabetes, arthritis, and other inflammatory disorders (Ixtaina and others 2012). Chia seeds have been successfully used to improve the
Hemp flour crackers with green tea . . . Table 2–Coded values and treatment levels for the mixture, simplex centroid, 2 component experimental design for the preparation of gluten-free crackers. Coded values Sample nr
C: Food Chemistry
0 4 3 2 1 a
Actual values
Standard order
Run order
X1
X2
Hemp oil presscake flour (%), X1
Decaffeinated green tea leaves (g), X2
2 1 4 3 5
1 2 3 4 5
0 1 0.75 0.5 0.25
1 0 0.25 0.5 0.75
0 40 30 20 10
8 0 2 4 6
X1 = Percent of added hemp oil press-cake flour based on total flour weight (w/w). X2 = Amount of decaffeinated green tea leaves added to the total mix (g).
b
Table 3–Formulation of the gluten-free crackers with incorporated hemp flour and decaffeinated green tea leaves.
Ingredients Hemp flour (%) Green tea leaves (g) Brown rice flour Hemp flour ∗ Chia seeds ∗ Water ∗ Canola oil ∗ Sodium bicarbonate ∗ Sugar ∗ Sea salt Total weight ∗
baked in a forced-air convection oven at 260 °C for 7 min. After cooling for 60 min at ambient temperature (21 °C), the weight of the crackers was determined and they were packed in double, Weight (g) high-density polyethylene bags, and stored in a freezer prior to the Sample Sample Sample Sample Sample physicochemical and sensory evaluation. 0 0 8 150.0 0.0 15.0 80.0 40.0 1.2 2.0 3.5 299.7
1 10 6 135.0 15.0 15.0 80.0 40.0 1.2 2.0 3.5 297.7
2 20 4 120.0 30.0 15.0 80.0 40.0 1.2 2.0 3.5 295.7
3 30 2 105.0 45.0 15.0 80.0 40.0 1.2 2.0 3.5 293.7
4 40 0 90.0 60.0 15.0 80.0 40.0 1.2 2.0 3.5 291.7
Fixed amount of an ingredient among different formulations.
Materials and Methods Hemp seed (Cannabis sativa L.) flour was provided by Hemp Oil Canada Inc. (Manitoba, Canada). All other ingredients, including organic decaffeinated green tea leaves (Camellia sinensis) were purchased from a local supermarket. All chemicals used were of analytical grade and supplied by Merck (Darmstadt, Germany). Proximate analyses, minerals and vitamins profile of brown rice and hemp oil press-cake flours, as well as black chia (Salvia hispanica L.) seeds, as main ingredients of interest, are presented in Table 1.
Crackers preparation Five batches of dough, where brown rice flour was replaced by hemp flour by 0% to 40%, were prepared according to the mixture simplex centroid design with 2 components, 5 design points, and 2 design degrees (Table 2). Formulations (total weight) are presented in Table 3. The formula for the sample nr 0 (100% brown rice flour) was developed based on our preliminary results (unpublished study). Leavened dough was prepared by mixing all dry ingredients, except for chia seeds, using a laboratory mixer (Kitchen Aid, St. Joseph, Mich., U.S.A.) at speed nr 3 for 3 min. Once well blended, the rest of the ingredients were added. Chia seeds were prepared by hydrating (soaking) 40 g of seed with 80 g of water and allowed for 20 min at ambient temperature (23 o C) for swelling, after which they were added to the dough and mixed for 5 more min. The dough rested for 45 min before sheeting. The resulting dough was shaped by hand using a Teflon pin roll into a sheet that was 4 mm thick. A plastic cookie cutter (63 mm in diameter) was used to cut 8 crackers from 1 batch of the dough. Raw pieces were placed on a perforated (mashed) baking tray and C320 Journal of Food Science r Vol. 79, Nr. 3, 2014
Physicochemical and sensory analysis Proximate analyses of samples were conducted using official methods of analysis (AOAC 2011). Eight pieces (in triplicate) were analyzed for physical measurements: weight, height, and diameter and averages of 24 values are presented. The same procedure was applied for chemical analysis of all samples. Total phenolic content was determined using Folin-ciocalteu reagent (results expressed as mg of gallic acid equivalent GAE/g dry weight) as described by Li and others (2011). 2,2-Diphenyl-1picrylhydrazyl (DPPH) radical scavenging activity (μmol Trolox equivalent TE/g dry weight) was determined using a colorimetric method for the determination of total antioxidant activity of crackers as described by Plank and others (2012). Determination of vitamins was conducted according to the USP 32 (2009) method. The fatty acids determination (by gas chromatography) and the minerals (by the ICP-AES method and spectrometer) were analyzed as described by Radoˇcaj and others (2012). Tocopherols were analyzed according to the Official method (Ce 8–89) (Radoˇcaj and Dimi´c 2013). The color of the samples was determined using a chromameter (model CR-400, Minolta, Ramsey, N.J., U.S.A.) equipped with a software that automatically displayed the CIE (Commission Intrenationale de I’Eclairage) color values (L∗ , a∗ , and b∗ ). The chromameter used a xenon-pulse-diffused illumination (D65 illuminant) with 3 response detectors set at 0o viewing angle. The instrument was calibrated using a standard white plate (L∗ = 97.75, a∗ = – 0.49, and b∗ = 1.96). Water activity was determined using a Rotronic hygrometer (Instrument Corp., Hanppange, N.Y., U.S.A.). Approximately 10 g of sample was placed in the plastic container and water activity was determined after 20 min at 25 °C. Sensory analysis was performed by the sensory panel that consisted of 12 expert assessors according to the ISO 6658 (2005) standard using quantitative descriptive and sensory profile tests. The panelists evaluated 5 established attributes: appearance, color, flavor, crunchiness, and overall texture, for each prepared sample, using an intensity scale of a maximum overall sensory score of 9, for all samples presented (marked as 0 to 4), in a laboratory designed and equipped with respect to the ISO 8589 (2007) standard.
Experimental design and data analysis This study was designed as a mixture, simplex centroid, 2 components experiment. The varied components were the amount of hemp flour added to replace brown rice flour (X1 ) and the amount of added decaffeinated green tea leaves (X2 ) in order to evaluate their impact on the finished product (gluten-free crackers) characteristics in randomly assigned runs with replications. All mixes and baked crackers were prepared in triplicate. Analytical measurements were conducted in triplicate for all samples and results were recorded as a mean ± standard deviations SD. Analysis of variance (one-way ANOVA) at P < 0.05, and a Tukey’s test at P < 0.05 were performed to analyze the significant differences among the samples’ means (pairwise comparisons) using Minitab software version 16 (State College, Pa., U.S.A.). Statistical analysis was performed using MS Excel version 2007 with analysis Toolpack.
Results and Discussion Proximate analysis of hemp press-cake and brown rice flours, as well as chia seeds, as main ingredients, are presented in Table 1. It can be seen that the protein and crude fibers contents in chia seeds and hemp flour are much higher than in the brown rice flour, while all flours had high content of minerals and beta+gamma tocopherols. Carbohydrate content was much lower in the hemp flour and in the chia seeds than in the brown rice flour. Brown rice flour had a much better vitamins profile than hemp flour or chia seeds, and it was high in pyridoxine (94.1 ± 0.1 mg/100 g) and folic acid (2.6 ± 0.1 mg/100 g). A study by Sandoval-Oliveros and Paredes-Lopez (2013) has shown that proximate composition of chia seeds is in agreement with our results. Rendon-Villalobos and others (2012) have demonstrated that the addition of chia seeds had a very positive effect on nutritional properties, specifically levels of proteins, lipids, and total dietary fibers in the prepared corn tortillas. The total phenolic content of the decaffeinated green tea was 112.32 ± 0.89 mg GAE/g d.w., which is in agreement with the study of Yang and Liu (2013). However, the antioxidant activity of our sample was much higher (1784.65 ± 24.37 μmol TE/g d.w.) than reported by Yang and Liu (2013). Their study has also shown a significant linear relationship between total phenolic content and antioxidant activity of green tea, as well as antiproliferative activity in vitro for cancer prevention. In terms of formulations of samples, the only varied ingredients among samples were contents of hemp flour and decaffeinated green tea leaves, while amounts of other ingredients were fixed for all recipes (Table 3). The weight of crackers with added hemp flour was slightly higher than the sample made of brown rice flour due to an increased amount of proteins and fibers added. Most likely, the interaction between the proteins, hemp fibers, and chia mucilage fibers contributed to the tighter protein–carbohydrate matrix that did not expand during baking in sample nr 3 (with 30% of added hemp flour) and sample nr 4 (with 40% of added hemp flour), as it did in other samples. With an increase of hemp flour amounts, the moisture content of the crackers also increased (Table 5). Consequently, the diameter of crackers made with the addition of hemp flour was lower, especially in sample nr 4 (with the addition of 40% hemp flour) (Table 4). Compared to the brown rice flour crackers (4.57 ± 0.03 mm), the height of crackers increased with the increase of the added hemp flour (up to 30%), after which it suddenly dropped to 4.32 ± 0.04 mm. This is in agreement with the study of Ashoush and Gadallah (2011) who added mango peels
to the biscuits, as well as Kohajdova and others (2011) who investigated the addition of apple fibers to cookies, and observed the weight increase and diameter and height shrinkage. The observed changes could also be explained by the reduced amount of starch in the formulations due to smaller quantities of the brown rice flour that would gelatinize during the baking process and provide a more stable protein–carbohydrate matrix, where starch would expand more and consequently contribute to the elevated height. Wang and others (2013) concluded that the addition of hemp flour to the wheat flour mix could lead to a higher onset gelatination temperature and cause later plasticization of the starch–protein network during gas cell walls forming and decrease the dough surface’s mechanical strength in the baking process. The appearance of samples was very different in color, depending on the amount of hemp flour added (Figure 1). The instrumental measurement of color has shown significant differences in L∗ (lightness), a∗ (redness), and b∗ (yellowness) of the crackers. Namely, the sample nr 0 (without added hemp flour and with the addition of 40% (8 g) of green tea leaves) was the brightest with much higher intensity of the yellow and red hue, than the hempflour-enriched crackers (Table 4). This is in agreement with other studies that observed a great decrease in the L values due to the addition of hemp flour: to different doughs and breads (Wang and others 2013), extruded hemp/rice flour to energy bars (Norajit and others 2011), as well as notably darker cookies due to addition of apple fiber (Kojahdova and others 2011), and much darker biscuits due to added mango peels and seed kernels (Ashoush and Gadallah (2011). In addition, the Maillard reaction, together with the caramelization, is the main chemical event occurring during baking. The reaction occurs between the free amino group of lysine and other amino acids and the carbonyl groups of reducing sugars, leading to compounds responsible for the brown color of baked products (Capuano and others 2008) that also contributed to the darker color of the crackers. However, the color of samples determined by the sensory panel test (Table 4) was not significantly different between the majorities of samples, except for the sample nr 4 (with the addition of 40% hemp flour and no added green tea leaves). Similar findings for small changes in color between the samples are reported by Davidov-Pardo and others (2012) studying the cookies enriched with grape seed extracts. The prepared samples were very different in terms of physicochemical analysis. Water activity, as an indicator for microbiological stability, was below 0.60 in all samples. The low value for water activity indicated a potentially long shelf life at ambient temperature, without microbial spoilage for this snack that belongs to the low-moisture bakery products with aw < 0.6. Most low-moisture foods are designed to be storable for several months at room temperature and are shelf-stable (Smith and others 2004). Based on ANOVA analysis, total phenolic content and antioxidant activity of samples (Table 4) have shown significant differences depending on the amount of green tea leaves added (at P < 0.05). A significant difference was observed in terms of total phenols of 3.45 ± 0.09 mg GAE/g d.w. in sample nr 0 (where 8 g of green tea leaves added) and sample nr 4 (1.09 ± 0.18 mg GAE/g d.w.) with no addition of the green tea leaves. Similarly, the highest antioxidant activity was found in sample nr 0 (40.22 ± 1.42 μmol TE/g d.w.) and the lowest was found in the sample nr 4 (7.47 ± 1.61 μmol TE/g d.w.) with no addition of green tea leaves. In addition, hemp oil press-cake also contained phenols (TPC of 2.98 ± 0.05 mg GAE/ g d.w.) and had a high antioxidant activity (DPPH of 19.96 ± 0.53 μmol TE/g d.w.) that contributed to the Vol. 79, Nr. 3, 2014 r Journal of Food Science C321
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Hemp flour crackers with green tea . . .
Hemp flour crackers with green tea . . . Table 4–Physicochemical analysis, antioxidant properties, and sensory evaluation of gluten-free crackers. Parameter
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Hemp flour (%) Green tea leaves (g) Weight (g) Height (mm) Diameter (mm) Color L∗ a∗ b∗ Water activity TPC (mg GAE/g d.w.) DPPH (μmol TE/g d.w.) Sensory evaluation score Appearance Color Flavor Crunchiness Overall texture Overall score
Correlation r2
Sample
Sample
Sample
Sample
Sample
0 0 8 9.39 ± 0.12c 4.57 ± 0.03c 59.62 ± 0.31a
1 10 6 9.82 ± 0.22b 4.78 ± 0.04a 59.73 ± 0.54a
2 20 4 9.98 ± 0.07b 4.80 ± 0.04a 59.57 ± 0.56a
3 30 2 10.39 ± 0.14a 4.70 ± 0.02b 58.61 ± 0.24b
4 40 0 10.58 ± 0.21a 4.32 ± 0.04d 56.66 ± 0.27c
0.9330 0.9908 0.9921
46.47 ± 1.80a 6.12 ± 0.18a 16.65 ± 1.29a 0.55 ± 0.0a 3.45 ± 0.09a 40.22 ± 1.42a
45.42 ± 0.71a 4.13 ± 0.08b 14.78 ± 0.21a 0.39 ± 0.0b 2.75 ± 0.08b 33.67 ± 1.32b
40.47 ± 0.82b 4.39 ± 0.15b 11.60 ± 0.55b 0.42 ± 0.0b 2.65 ± 0.27c 31.19 ± 2.57c
37.34 ± 0.28c 4.42 ± 0.06b 9.25 ± 0.42b 0.51 ± 0.0a 2.03 ± 0.06d 22.43 ± 0.92d
33.84 ± 1.00d 4.33 ± 0.17b 6.05 ± 1.41c 0.56 ± 0.0a 1.09 ± 0.18e 7.47 ± 1.61e
0.9812 0.7519 0.9968 0.7764 0.9662 0.9811
7.9 ± 0.7bc 7.9 ± 0.7a 7.7 ± 0.8bc 8.2 ± 0.6a 7.7 ± 0.5b 8.6 ± 0.3bc
8.3 ± 0.5ab 8.1 ± 0.8a 8.2 ± 0.4ab 8.3 ± 0.5a 7.9 ± 0.5b 8.8 ± 0.3ab
8.8 ± 0.5a 8.5 ± 0.9a 8.8 ± 0.5a 8.6 ± 0.5a 8.7 ± 0.5a 9.0 ± 0.1a
8.5 ± 0.5ab 8.3 ± 0.6a 8.7 ± 0.5a 8.6 ± 0.5a 8.7 ± 0.5a 8.4 ± 0.3c
7.4 ± 0.9c 6.1 ± 0.9b 7.3 ± 074c 8.6 ± 0.5a 8.5 ± 0.5a 7.8 ± 0.2d
0.9221 0.8688 0.8810 0.9135 0.8623 0.7040
Values are means ± SD; n = 3. Means in the same row followed by different superscript letters are significantly different (P < 0.05).
Table 5–Proximate analysis, minerals, and fatty acids profile of gluten-free crackers. Per 100 g Parameter Hemp flour (%) Green tea leaves (g) Water content (%) Ash (%) Protein content (g) Fat content (g) Crude fibers (g) Carbohydrates (g) Minerals (mg) Ca Fe Mg Mn K Zn PUFA MUFA SAFA Linoleic acid (ω-6) α-Linolenic acid (ω-3) ω-6/ω-3 ratio
Sample
Sample
Sample
Sample
Sample
0 0 8 7.95 ± 0.12a 2.61 ± 0.09e 6.47 ± 0.3e 22.06 ± 0.08e 4.91 ± 0.10e 56.00 ± 0.22a
1 10 6 5.62 ± 0.03c 3.74 ± 0.08d 9.25 ± 0.28d 23.26 ± 0.12d 6.84 ± 0.12d 51.29 ± 0.15b
2 20 4 6.60 ± 0.43b 4.88 ± 0.10c 11.51 ± 0.37c 23.71 ± 0.15c 8.59 ± 0.10c 44.91 ± 0.13c
3 30 2 6.69 ± 0.10b 5.92 ± 0.10b 14.11 ± 0.26b 24.34 ± 0.11b 10.46 ± 0.11b 38.48 ± 0.22d
4 40 0 7.34 ± 0.26a 6.81 ± 0.13a 16.40 ± 0.40a 24.86 ± 0.09a 12.26 ± 0.10a 32.33 ± 0.14e
64.04 ± 0.17e 1.11 ± 0.03e 5.67 ± 0.12e 1.21 ± 0.07e 145.54 ± 0.52e 1.47 ± 0.08b 7.62 ± 0.10e 10.73 ± 0.10b 1.89 ± 0.08a 4.73 ± 0.78e 2.89 ± 0.09c 1.66c
72.46 ± 0.15d 1.56 ± 0.07d 17.96 ± 0.10d 1.66 ± 0.07d 166.82 ± 0.32d 1.55 ± 0.06ab 8.35 ± 0.09d 11.17 ± 0.08a 1.99 ± 0.06a 5.25 ± 0.10d 3.09 ± 0.09bc 1.7bc
78.47 ± 0.12c 1.99 ± 0.07c 29.97 ± 0.10c 2.09 ± 0.08c 182.79 ± 0.55c 1.59 ± 0.04ab 8.83 ± 0.12c 11.24 ± 0.11a 2.01 ± 0.08a 5.59 ± 0.10c 3.19 ± 0.10ab 1.75ab
85.24 ± 0.11b 2.38 ± 0.07b 42.27 ± 0.38b 2.56 ± 0.07b 199.73 ± 0.38b 1.64 ± 0.05b 9.33 ± 0.13b 11.35 ± 0.11a 2.05 ± 0.08a 5.93 ± 0.08b 3.35 ± 0.10ab 1.77ab
91.78 ± 0.58a 2.85 ± 0.08a 54.65 ± 0.41a 3.01 ± 0.08a 216.21 ± 0.33a 1.68 ± 0.07a 9.84 ± 0.98a 11.42 ± 0.08a 2.09 ± 0.08a 6.3 ± 0.108a 3.45 ± 0.11a 1.83a
PUFA—polyunsaturated fatty acids; MUFA—monounsaturated fatty acids; SAFA—saturated fatty acids. Values are means ± SD; n = 3. Means in the same row followed by different superscript letters are significantly different (P < 0.05).
overall value of the crackers. Norajit and others (2011) studied the effects of defatted hemp flour at 20%, 30%, and 40% levels (based on the rice flour) on the physicochemical properties of extruded rice. Their results for the protein content of the extruded snack are in agreement with our results, while the ash content is slightly lower than in our samples. Total phenolic content of their samples was lower for samples with 20% and 30% hemp flour replacement compared to what was determined in our crackers. Davidov-Pardo and others (2012) found that the antioxidant activity of cookies enriched with grape seed extracts was high at 7.8 ± 0.1 μmol /g. Our crackers had up to 8 times higher antioxidant activity (sample nr 0—with the addition of 8 g of green tea leaves) than their
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sample. In addition, our results of total phenolic content are comparable to the study of gluten-free crackers based on buckwheat flour by Sedej and others (2011). What was also interesting in the study of Davidov-Pardo and others (2012) was the fact based on their consumers’ study: if provided with the health benefits information and functionality of antioxidants in the cookies, 60% of consumers stated that they were willing to purchase cookies enriched with antioxidants. Sensory evaluation in our study confirmed that crackers were successfully developed to be tasty, crunchy, and indicative to contain green tea because of the intensive green color of the crackers. Appearance, color, and flavor were slightly different among all samples, except
for the sample nr 4 (with the addition of 40% hemp flour and addition of green tea leaves) that was much darker and received the lowest sensory score (7.8±0.2) and considered as “unacceptable.” Two samples: nr 1 (with the addition of 10% hemp flour and 6 g of green tea leaves) and sample nr 2 (with the addition of 20% hemp flour and 4 g of green tea leaves) were described to have a very pleasant, nutty flavor, “healthy” appearance and a very distinctive crunchiness. Sample nr 2 (with the addition of 20% hemp flour and 4 g of decaffeinated green tea leaves) was voted as the best sample; ready to proceed with a consumer’s study. Once the sensory evaluation was completed, the crackers’ formulations were revealed to the panel. Because of the enrichment with the decaffeinated green tea leaves as antioxidants, as well as much more favorable nutritional profile due to the added hemp flour, the sensory panel was unanimous in their decision to purchase those crackers if available. Proximate analysis of all samples is presented in Table 5. The ash content was significantly different in all samples, and as expected, progressively rose with an increase in the amount of added hemp flour, which was rich in minerals (Table 5). The fat, that is, oil content of the samples was high due to canola oil and chia seeds use. However, canola oil is known to have high polyunsaturated fatty acids (PUFAs) content along with the alpha-linolenic fatty acid (Radoˇcaj and Dimi´c 2013). Crackers were high in monounsaturated fatty acids (MUFAs) as well as PUFAs. The saturated fatty acids (SAFAs) content was very low in all crackers (1.89 ± 0.08 g/100 g to 2.09±0.08 g/100 g) (Table 5). The protein content was the highest in the sample nr 4 (16.40 ± 0.40 g/100 g) (with the addition of 10% hemp flour and 6 g of green tea leaves), and it was high in samples nr 2 (11.51 ± 0.37 g/100 g) (with the addition of 20% hemp flour and 4 g of green tea leaves) and nr 3 (14.11±0.26 g/100 g) (with the addition of 30% hemp flour and 2 g of green tea leaves). The addition of hemp flour caused a significant fiber content increase of all samples (6.84 ± 0.12 to 12.26 ± 0.03 g/100 g) compared to the brown rice flour sample (6.47±0.30 g/100 g). The increase in
the proteins, total fibers, minerals, and essential fatty acids content suggests that a new product has better nutritional characteristics than the sample without added hemp flour. Gluten-free crackers developed by Han and others (2010) using pulse flours had a much lower level of proteins, fibers, and minerals than our crackers. Their samples did not contain any essential fatty acids. The content of omega-6 increased significantly (at P < 0.05) with the addition of hemp flour. The omega-3 fatty acids content was lowest in the sample without hemp flour (2.89 ± 0.09 g/100 g) and the highest in the sample nr 4 (with the addition of 40% hemp flour and no added green tea leaves), which was not significantly different from the omega-3 fatty acids content in samples nr 2 (with the addition of 20% hemp flour and 4 g of green tea leaves) and 3 (with the addition of 30% hemp flour and 2 g of green tea leaves). Imbalances in the intake of omega-6 and omega-3 fatty acids are associated with various diseases. A lower ratio of omega-6/omega3 fatty acids, such as 2 to 3 : 1, is more desirable in reducing the risk of many chronic diseases in Western society, in which a diet is deficient in omega−3 fatty acids and has excessive amounts of omega−6 fatty acids, compared to the diet on which human beings evolved (Simopoulos 2002a; Strandvik 2011). Today, in Western diets, the ratio of omega-6 to omega-3 fatty acids ranges from 10 to 20 : 1 instead of the traditional range of 1 to 2 : 1. Studies indicate that a high intake of omega-6 fatty acids shifts the physiologic state to one that is prothrombotic and proaggregatory, characterized by increases in blood viscosity, vasospasm, and vasoconstriction and decreases in bleeding time, whereas omega-3 fatty acids have antiinflammatory, antithrombotic, antiarrhythmic, hypolipidemic, and vasodilatory properties (Simopoulos 2002b). An extensive study of various cold-pressed oils (Radoˇcaj and Dimi´c 2013) has shown that hemp oil had not only the high content of omega-6 and omega-3 fatty acids, but also that their ratio was well balanced (3.1). In all prepared crackers, the content of omega-6 and omega-3 fatty acids was perfectly balanced, as their ratio was 1.66 to 1.83 among the samples (Table 5).
Figure 1–Appearance of gluten-free crackers based on hemp oil press-cake and brown rice flour with the addition of decaffeinated green tea leaves.
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Hemp flour crackers with green tea . . .
Hemp flour crackers with green tea . . .
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All samples had significant amounts of calcium, iron, magnesium, manganese, potassium, and zinc. For example, a study (de Oliveira and others 2009) of gluten-free cookies enriched with guarana and catuba plants to achieve higher contents of copper, iron, and zinc demonstrated that their cookies had iron present at 4.50 ± 0.34 mg/100 g and zinc at 1.32 ± 0.09 mg/100 g, which compared to our crackers, were higher in iron, but lower in zinc (Table 5). In terms of the use of hemp oil press-cake flour, the carbohydrate content reduction, along with the proteins, essential fatty acids, minerals, and fiber content increase, was a main goal of this study in terms of improving the nutritional profile of the gluten-free crackers. Likewise, increasing the total phenols and antioxidant properties of crackers by usage of decaffeinated green tea leaves was also successfully accomplished. The correlation coefficients between the amount of added hemp oil press-cake, decaffeinated green tea leaves, and some product variables are presented in Table 4. This table shows that there was a significant correlation between the amount of added ingredients and physicochemical attributes, such as weight, height, diameter, color, and water activity. Also, total phenolic content and antioxidant activities were highly correlated to the addition of hemp flour and decaffeinated green tea leaves. There was a very significant positive correlation between the added green tea leaves and total phenolic content (r = 0.9710 at P < 0.05), and between the added hemp flour and total phenolic content (r = 0.944 at P < 0.05). Optimization of the responses was conducted using the same software as explained earlier, based on the maximized values for protein, fibers, omega-3 fatty acids content, as well as for the antioxidant activity and overall score. The suggested values for the addition of the hemp oil press-cake was 20% with 4 g of decaffeinated green tea leaves that would provide protein content of 14.1 g/100 g; fibers content of 8.4 g/100 g; omega-3 fatty acids content of 3.2 g/100 g; antioxidant activity measured via DPPH value of 30.3 μmol TE/g d.w.; and an overall score of 8.9. The recommendation based on this study is that hemp flour (hemp oil press-cake) may be used as a functional ingredient in the formulation of a cracker based on the brown rice flour and that these crackers had enhanced nutritional quality, as it was also concluded by Norajit and others (2011) in extruded rice/hemp product.
Conclusions A functional gluten-free food product was developed to broaden consumers’ choices in this segment of value added products. This study was an attempt to incorporate highly nutritious hemp flour, as a by-product of the cold-pressed hemp oil (functional ingredient) in combination with decaffeinated green tea leaves, in a portable snack type cracker. Based on our research, it was suggested that hemp oil press-cake may be a good and original source for crackers development, which enables valorization of this byproduct (that is generally considered as a waste) in other food applications. A brown rice flour cracker can be enriched with hemp flour by up to 30% and green tea leaves by 8 g in order to increase the total proteins, fibers, essential fatty acids, mineral content, as well as total phenolic and antioxidant activity, thereby providing a value-added, healthier snack, compared to the brown rice flour cracker. The enrichment caused a significant change in the physicochemical profile of the prepared samples, and the sensory evaluation by the panel. Samples nr 1 (hemp flour addition of 10% and green tea leaves of 6 g) and nr 2 (hemp flour addition of 20% and green tea leaves of 4 g) had the highest sensory score (8.8 and C324 Journal of Food Science r Vol. 79, Nr. 3, 2014
9.0, respectively). They achieved an increase in the total fibers (for about 43% and 78%, respectively) and protein content (for about 40% and 87%, respectively), compared to the brown rice flour cracker. For samples nr 1 and 2, the addition of the decaffeinated green tea leaves provided very high radical scavenging (antioxidant) activity of 33.67 ± 1.32 μmol TE/g d.w. and 31.19 ± 2.57 μmol TE/g d.w., respectively. The optimized cracker formulations would be with 20% hemp flour and 4 g of decaffeinated green tea leaves incorporated into the dough formula.
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Hemp flour crackers with green tea . . .
Effects of Hemp (Cannabis sativa L.) Seed Oil Press-Cake and Decaffeinated Green Tea Leaves (Camellia sinensis) on Functional Characteristics of Gluten-Free Crackers Olga Radoˇcaj, Etelka Dimi´c, and Rong Tsao
Abstract: A mixture, simplex centroid, 2 components experimental design was used to evaluate the addition of hemp seed oil press-cake and decaffeinated green tea leaves, as functional ingredients to assess nutritional characteristics and antioxidant properties of gluten-free crackers. All samples with added hemp flour had much better nutritional qualities than the brown rice flour crackers in terms of higher protein, crude fibers, minerals, and essential fatty acids content. Likewise, all samples with added decaffeinated green tea leaves had much better antioxidant properties than crackers with no added green tea leaves. All crackers with added hemp flour had a significantly increased fiber content (39% to 249%) and decreased carbohydrate content (8.4% to 42.3%), compared to the brown rice flour crackers. All samples had antioxidant properties, even without the addition of green tea leaves. Optimization of the responses was conducted based on the maximized values for protein, fibers, omega-3 fatty acids content, as well as for the antioxidant activity and overall score. The suggested values for the addition of the hemp oil press-cake was 20% (total flour weight) with 4 g of decaffeinated green tea leaves that would provide protein content of 14.1 g/100 g; fibers content of 8.4 g/100 g; omega-3 fatty acids content of 3.2 g/100 g; antioxidant activity measured via 2,2-diphenyl-1-picrylhydrazyl value of 30.3 μmol TE/g d.w.; and an overall score of 8.9. This formulation has demonstrated potential application in the baking industry and marketing of these gluten-free crackers as a value-added functional product. Keywords: crackers, functional food, gluten-free, green tea leaves, hemp
Hemp seed oil press-cake as a by-product of cold-pressed oil processing and brown rice flour were used to design a functional gluten-free snack-type product—savory crackers. All crackers were high in minerals, fibers, and omega-3 fatty acids with a desirable omega-6/omega-3 fatty acids ratio. Green tea leaves were added to improve antioxidant activity, which greatly contributed to their functional properties. This qualified the crackers as a healthy snack with a minimal content saturated fatty acids and an abundance of polyunsaturated and monounsaturated fatty acids that originated from chia seeds residual oil present in the hemp flour.
Practical Application:
Introduction The term “celiac,” originates from the Greek word “koiliakos,” meaning “suffering in the bowel.” Coeliac disease (CD) is a common, chronic inflammatory malabsorptive disorder of the small intestinal mucosa, characterized by an improper immune response to ingested wheat gluten (composed of gliadin and glutenin) and related cereal proteins in genetically predisposed individuals, resulting in villous atrophy, crypt hyperplasia, and lymphocytic infiltration in the small intestine. Elimination of the immunogenic proteins from diet leads to clinical and histological improvement. Modern serological screening, followed by small intestinal biopsy, has revealed that CD is one of the most prevalent food (around 1% of the general population) intolerances worldwide and can occur at any age (Alaedini and Green 2008; Gainer 2011; Rivera and
MS 20131497 Submitted 10/20/2013, Accepted 12/29/2013. Authors Radoˇcaj and Dimi´c are with Faculty of Technology, Univ. of Novi Sad, Bulevar cara Lazara 1, 21000, Novi Sad, Serbia. Author Tsao is with Guelph Food Research Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, Ontario, N1G 5C9, Canada. Direct inquiries to author Radoˇcaj (E-mail: [email protected]).
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others 2013). Therefore, a development of gluten-free food with functional properties, especially to replace wheat proteins, fibers, and minerals, is very important in order to provide not only better selection, but also more nutritious food to the consumers that belong to this segment of population. The global market for functional foods was projected to exceed U.S. $243 billion by 2015, the U.S.A., Europe, and Japan being the dominant regions with a combined share of more than 85% (Sheiber 2012). The emergence of a new market segment called “Health and Wellness” reached a global value of U.S. $625 billion in 2012 (Khan and others 2013). Definitions, as well as regulatory requirements of functional foods, vary from country to country (Doyon and Labrecque 2008; Malla and others 2013). Canada defines functional food as a food similar in appearance to, or may be, a conventional food that is consumed as part of a usual diet, and is demonstrated to have physiological benefits and/or reduce the risk of chronic disease beyond basic nutritional functions, that is, they contain a bioactive compound. A nutraceutical is a product isolated or purified from foods that is generally sold in medicinal forms not usually associated with foods. A nutraceutical is demonstrated to have a physiological benefit or provide R C 2014 Institute of Food Technologists
doi: 10.1111/1750-3841.12370 Further reproduction without permission is prohibited
Hemp flour crackers with green tea . . . Table 1–Proximate analysis with tocopherols, minerals, and vitamins profile of hemp oil press-cake, brown rice flour, and chia seeds. Analysis (g/100 g)
Hemp oil-press Brown rice cake flour flour
Moisture Ash Fat Protein Crude fibers Carbohydrates (by difference) Tocopherols (mg/kg) α β+γ δ Minerals (mg/kg) Ca Cu Fe Mg Mn K Na Zn Vitamins (mg/100 g) Vit A Folic acid Riboflavin Pyridoxine
6.35 ± 0.07c
5.24 ± 0.09a 9.53 ± 0.12b 32.21 ± 0.17a 43.87 ± 0.05a 2.80 ± 0.35b 0.0 ± 0.0b 12.1 ± 0.0b 0.0 ± 0.0b
Chia seeds
9.87 ± 0.10a
8.19 ± 0.32b 1.44 ± 0.01c 3.84 ± 0.17b 2.72 ± 0.10c 32.83 ± 0.48a 6.91 ± 0.21c 20.72 ± 0.10b 2.26 ± 0.18c 33.18 ± 0.11b 76.80 ± 0.44a 1.24 ± 0.15c 1.61 ± 0.1a 5.32 ± 0.1c 0.51 ± 0.1a
0.0 ± 0.0b 67.6 ± 0.3a 0.0 ± 0.0b
20.6 ± 0.6c 533.1 ± 12.9a 120.3 ± 2.8b 0.1 ± 0.0.0a 0.1 ± 0.0.0a 0.1 ± 0.0.0a 6.6 ± 0.0.1a 0.6 ± 0.0.0c 4.3 ± 0.0.1b 173.5 ± 3.7b 102.6 ± 0.5c 331.6 ± 6.7a 7.8 ± 0.1b 1.5 ± 0.0c 14.2 ± 0.2a 432.3 ± 3.5b 199.1 ± 4.5c 671.9 ± 11.5a 15.2 ± 0.2b 19.0 ± 0.1a 3.4 ± 0.1c 2.4 ± 0.1b 1.8 ± 0.1c 2.3 ± 0.1a 1.00 ± 0.0a 0.0 ± 0.0b 2.6 ± 0.1a 0.0 ± 0.0b
0.0 ± 0.0b 2.6 ± 0.1a 1.5 ± 0.0a 4.1 ± 0.1a
0.0 ± 0.0b 0.0 ± 0.0b 2.6 ± 0.1a 0.0 ± 0.0b
Values are means ± SD; n = 3. Means in the same row followed by different superscript letters are significantly different (P < 0.05).
rheology of gluten-free dough based on chestnut flour due to the mucilage fibers that form viscous-gel-type systems (Moreira and others 2013). Crackers are defined as thin, hard-baked, crisp wafers or biscuits, usually made of unsweetened and unleavened dough using soft wheat flour. In the production of gluten-free crackers, additional ingredients must be used to compensate for a lack of wheat gluten (Han and others 2010). This is the primary reason we added hydrated chia seeds to improve the texture of the crackers’ dough. To the best of our knowledge, no data have been reported yet on the utilization of hemp oil press-cake flour and decaffeinated green tea leaves as functional ingredients, with regard to its nutritional and functional properties, for the preparation of gluten-free crackers. Therefore, our results were compared with gluten-free crackers made using different flours. Savory-type crackers with hemp flour have been chosen to blend the green tea leaves with green colored hemp flour providing a convenient, functional snack-type food. The objectives of this study were: (1) to investigate a possible use for hemp oil press-cake in the gluten-free crackers, (2) to evaluate the effects of the hemp flour primarily on the changes in chemical characteristics of crackers, such as contents of omega-3 and omega-6 fatty acids, proteins, fibers, and minerals content of the samples, (3) to investigate the effect of decaffeinated green tea leaves as an antioxidant in the gluten-free crackers, and (4) to determine the optimum amount of hemp flour, as a replacement for brown rice flour, which would deliver maximum nutritional benefits, as well as the optimum amount of green tea leaves, which would deliver maximum antioxidant properties for gluten-free crackers that will be acceptable by the sensory panel. Vol. 79, Nr. 3, 2014 r Journal of Food Science C319
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protection against chronic disease (Agriculture and Agri-Food Canada 2013). The number of discrete functional food ingredients is increasing, and functional foods are widely used in many everyday food products (Griffiths and others 2009). Functional foods have been developed in virtually all food categories. These products have mainly been launched in the dairy, confectionary, soft drinks, bakery, and baby-food markets (Siro and others 2008). One of the examples often quoted within the functional food sector is the introduction of margarine spreads fortified with plant sterols (Henry 2010). Among other functional foods, bakery products were also investigated as gluten-free options: almond- and peanutflour-based cookies fortified with iron (Granato and Ellendersen 2009); raw and popped amaranth-flour-based breads and cookies rich in protein (de la Barca and others 2010); protein and crude fibers enriched biscuits based on plantain and chickpeas flours (Yadav and others 2012). However, research in Europe has shown that there is a confusion among consumers about functional foods and they need to be informed to understand the exact benefits of such food in order to purchase it (Blades 2000; Annunziata and Vecchio 2011). The use of by-products of the food processing industry as a source of functional ingredients such as antioxidants, tocopherols, carotenoids, phenols, fibers, proteins, and so on, is on the rise. Potential high-volume by-products of the food industry are fruits and vegetables (Schieber and others 2001) and cold- pressed seed oil cakes (flours) such as camelina (Terpinc and others 2012); pumpkin, parsley, mullein, cardamom, milk thistle (Parry and others 2008); flax (Ogunronbi and others 2011); grape seed flour (Ozvural and Vural 2011); and sesame seed oil cake (Nascimento and others 2012), to name a few. For example, a hull-less pumpkin oil press-cake was recently used to develop a spread rich in omega-3 and omega-6 fatty acids, minerals, and proteins (Radoˇcaj and others 2012). Hemp seeds, which contain a low level (0.3%) of tetrahydrocannabinol (THC), are legally grown in Europe and Canada and are of high nutritional value. Oil press-cake, as a by-product of the cold-pressing hemp oil process, is rich in proteins, fibers, phytochemicals, minerals, linoleic (omega-6), and alpha-linolenic (omega-3) essential fatty acids, as well as gamma-tocopherols. Two main proteins in hemp seeds are edistin and albumin. These have high amounts of essential amino acids and are exceptionally high in amino acid arginine. Hempseed proteins are comparable to the egg white and soy protein (Callaway 2004). Defatted hemp flour was used in the past for the fortification of energy bars (Norajit and others 2011). Green tea is made by steaming or frying fresh tea leaves at elevated temperatures to prevent enzymatic oxidation. It contains polyphenols, which include flavanols (catechins), flavandiols, flavonoids, and phenolic acids (Chow and Hakim 2011). Tea catechins have been shown to have health benefits including cancer prevention of many types (Cabrera and others 2006), decreasing LDL cholesterol level (Kim and others 2011), and antiobesity effects (Cardoso and others 2013). Green tea extract was used to stabilize the lipid oxidation rate of omega-3 oils incorporated into table spreads (O’Dwyer and others 2012). Chia seeds are high in proteins, fibers, minerals, and highly unsaturated fatty acids such as alpha-linolenic (approximately 60%) omega-3 essential fatty acid and have been used in the prevention and treatment of coronary artery disease, hypertension, diabetes, arthritis, and other inflammatory disorders (Ixtaina and others 2012). Chia seeds have been successfully used to improve the
Hemp flour crackers with green tea . . . Table 2–Coded values and treatment levels for the mixture, simplex centroid, 2 component experimental design for the preparation of gluten-free crackers. Coded values Sample nr
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0 4 3 2 1 a
Actual values
Standard order
Run order
X1
X2
Hemp oil presscake flour (%), X1
Decaffeinated green tea leaves (g), X2
2 1 4 3 5
1 2 3 4 5
0 1 0.75 0.5 0.25
1 0 0.25 0.5 0.75
0 40 30 20 10
8 0 2 4 6
X1 = Percent of added hemp oil press-cake flour based on total flour weight (w/w). X2 = Amount of decaffeinated green tea leaves added to the total mix (g).
b
Table 3–Formulation of the gluten-free crackers with incorporated hemp flour and decaffeinated green tea leaves.
Ingredients Hemp flour (%) Green tea leaves (g) Brown rice flour Hemp flour ∗ Chia seeds ∗ Water ∗ Canola oil ∗ Sodium bicarbonate ∗ Sugar ∗ Sea salt Total weight ∗
baked in a forced-air convection oven at 260 °C for 7 min. After cooling for 60 min at ambient temperature (21 °C), the weight of the crackers was determined and they were packed in double, Weight (g) high-density polyethylene bags, and stored in a freezer prior to the Sample Sample Sample Sample Sample physicochemical and sensory evaluation. 0 0 8 150.0 0.0 15.0 80.0 40.0 1.2 2.0 3.5 299.7
1 10 6 135.0 15.0 15.0 80.0 40.0 1.2 2.0 3.5 297.7
2 20 4 120.0 30.0 15.0 80.0 40.0 1.2 2.0 3.5 295.7
3 30 2 105.0 45.0 15.0 80.0 40.0 1.2 2.0 3.5 293.7
4 40 0 90.0 60.0 15.0 80.0 40.0 1.2 2.0 3.5 291.7
Fixed amount of an ingredient among different formulations.
Materials and Methods Hemp seed (Cannabis sativa L.) flour was provided by Hemp Oil Canada Inc. (Manitoba, Canada). All other ingredients, including organic decaffeinated green tea leaves (Camellia sinensis) were purchased from a local supermarket. All chemicals used were of analytical grade and supplied by Merck (Darmstadt, Germany). Proximate analyses, minerals and vitamins profile of brown rice and hemp oil press-cake flours, as well as black chia (Salvia hispanica L.) seeds, as main ingredients of interest, are presented in Table 1.
Crackers preparation Five batches of dough, where brown rice flour was replaced by hemp flour by 0% to 40%, were prepared according to the mixture simplex centroid design with 2 components, 5 design points, and 2 design degrees (Table 2). Formulations (total weight) are presented in Table 3. The formula for the sample nr 0 (100% brown rice flour) was developed based on our preliminary results (unpublished study). Leavened dough was prepared by mixing all dry ingredients, except for chia seeds, using a laboratory mixer (Kitchen Aid, St. Joseph, Mich., U.S.A.) at speed nr 3 for 3 min. Once well blended, the rest of the ingredients were added. Chia seeds were prepared by hydrating (soaking) 40 g of seed with 80 g of water and allowed for 20 min at ambient temperature (23 o C) for swelling, after which they were added to the dough and mixed for 5 more min. The dough rested for 45 min before sheeting. The resulting dough was shaped by hand using a Teflon pin roll into a sheet that was 4 mm thick. A plastic cookie cutter (63 mm in diameter) was used to cut 8 crackers from 1 batch of the dough. Raw pieces were placed on a perforated (mashed) baking tray and C320 Journal of Food Science r Vol. 79, Nr. 3, 2014
Physicochemical and sensory analysis Proximate analyses of samples were conducted using official methods of analysis (AOAC 2011). Eight pieces (in triplicate) were analyzed for physical measurements: weight, height, and diameter and averages of 24 values are presented. The same procedure was applied for chemical analysis of all samples. Total phenolic content was determined using Folin-ciocalteu reagent (results expressed as mg of gallic acid equivalent GAE/g dry weight) as described by Li and others (2011). 2,2-Diphenyl-1picrylhydrazyl (DPPH) radical scavenging activity (μmol Trolox equivalent TE/g dry weight) was determined using a colorimetric method for the determination of total antioxidant activity of crackers as described by Plank and others (2012). Determination of vitamins was conducted according to the USP 32 (2009) method. The fatty acids determination (by gas chromatography) and the minerals (by the ICP-AES method and spectrometer) were analyzed as described by Radoˇcaj and others (2012). Tocopherols were analyzed according to the Official method (Ce 8–89) (Radoˇcaj and Dimi´c 2013). The color of the samples was determined using a chromameter (model CR-400, Minolta, Ramsey, N.J., U.S.A.) equipped with a software that automatically displayed the CIE (Commission Intrenationale de I’Eclairage) color values (L∗ , a∗ , and b∗ ). The chromameter used a xenon-pulse-diffused illumination (D65 illuminant) with 3 response detectors set at 0o viewing angle. The instrument was calibrated using a standard white plate (L∗ = 97.75, a∗ = – 0.49, and b∗ = 1.96). Water activity was determined using a Rotronic hygrometer (Instrument Corp., Hanppange, N.Y., U.S.A.). Approximately 10 g of sample was placed in the plastic container and water activity was determined after 20 min at 25 °C. Sensory analysis was performed by the sensory panel that consisted of 12 expert assessors according to the ISO 6658 (2005) standard using quantitative descriptive and sensory profile tests. The panelists evaluated 5 established attributes: appearance, color, flavor, crunchiness, and overall texture, for each prepared sample, using an intensity scale of a maximum overall sensory score of 9, for all samples presented (marked as 0 to 4), in a laboratory designed and equipped with respect to the ISO 8589 (2007) standard.
Experimental design and data analysis This study was designed as a mixture, simplex centroid, 2 components experiment. The varied components were the amount of hemp flour added to replace brown rice flour (X1 ) and the amount of added decaffeinated green tea leaves (X2 ) in order to evaluate their impact on the finished product (gluten-free crackers) characteristics in randomly assigned runs with replications. All mixes and baked crackers were prepared in triplicate. Analytical measurements were conducted in triplicate for all samples and results were recorded as a mean ± standard deviations SD. Analysis of variance (one-way ANOVA) at P < 0.05, and a Tukey’s test at P < 0.05 were performed to analyze the significant differences among the samples’ means (pairwise comparisons) using Minitab software version 16 (State College, Pa., U.S.A.). Statistical analysis was performed using MS Excel version 2007 with analysis Toolpack.
Results and Discussion Proximate analysis of hemp press-cake and brown rice flours, as well as chia seeds, as main ingredients, are presented in Table 1. It can be seen that the protein and crude fibers contents in chia seeds and hemp flour are much higher than in the brown rice flour, while all flours had high content of minerals and beta+gamma tocopherols. Carbohydrate content was much lower in the hemp flour and in the chia seeds than in the brown rice flour. Brown rice flour had a much better vitamins profile than hemp flour or chia seeds, and it was high in pyridoxine (94.1 ± 0.1 mg/100 g) and folic acid (2.6 ± 0.1 mg/100 g). A study by Sandoval-Oliveros and Paredes-Lopez (2013) has shown that proximate composition of chia seeds is in agreement with our results. Rendon-Villalobos and others (2012) have demonstrated that the addition of chia seeds had a very positive effect on nutritional properties, specifically levels of proteins, lipids, and total dietary fibers in the prepared corn tortillas. The total phenolic content of the decaffeinated green tea was 112.32 ± 0.89 mg GAE/g d.w., which is in agreement with the study of Yang and Liu (2013). However, the antioxidant activity of our sample was much higher (1784.65 ± 24.37 μmol TE/g d.w.) than reported by Yang and Liu (2013). Their study has also shown a significant linear relationship between total phenolic content and antioxidant activity of green tea, as well as antiproliferative activity in vitro for cancer prevention. In terms of formulations of samples, the only varied ingredients among samples were contents of hemp flour and decaffeinated green tea leaves, while amounts of other ingredients were fixed for all recipes (Table 3). The weight of crackers with added hemp flour was slightly higher than the sample made of brown rice flour due to an increased amount of proteins and fibers added. Most likely, the interaction between the proteins, hemp fibers, and chia mucilage fibers contributed to the tighter protein–carbohydrate matrix that did not expand during baking in sample nr 3 (with 30% of added hemp flour) and sample nr 4 (with 40% of added hemp flour), as it did in other samples. With an increase of hemp flour amounts, the moisture content of the crackers also increased (Table 5). Consequently, the diameter of crackers made with the addition of hemp flour was lower, especially in sample nr 4 (with the addition of 40% hemp flour) (Table 4). Compared to the brown rice flour crackers (4.57 ± 0.03 mm), the height of crackers increased with the increase of the added hemp flour (up to 30%), after which it suddenly dropped to 4.32 ± 0.04 mm. This is in agreement with the study of Ashoush and Gadallah (2011) who added mango peels
to the biscuits, as well as Kohajdova and others (2011) who investigated the addition of apple fibers to cookies, and observed the weight increase and diameter and height shrinkage. The observed changes could also be explained by the reduced amount of starch in the formulations due to smaller quantities of the brown rice flour that would gelatinize during the baking process and provide a more stable protein–carbohydrate matrix, where starch would expand more and consequently contribute to the elevated height. Wang and others (2013) concluded that the addition of hemp flour to the wheat flour mix could lead to a higher onset gelatination temperature and cause later plasticization of the starch–protein network during gas cell walls forming and decrease the dough surface’s mechanical strength in the baking process. The appearance of samples was very different in color, depending on the amount of hemp flour added (Figure 1). The instrumental measurement of color has shown significant differences in L∗ (lightness), a∗ (redness), and b∗ (yellowness) of the crackers. Namely, the sample nr 0 (without added hemp flour and with the addition of 40% (8 g) of green tea leaves) was the brightest with much higher intensity of the yellow and red hue, than the hempflour-enriched crackers (Table 4). This is in agreement with other studies that observed a great decrease in the L values due to the addition of hemp flour: to different doughs and breads (Wang and others 2013), extruded hemp/rice flour to energy bars (Norajit and others 2011), as well as notably darker cookies due to addition of apple fiber (Kojahdova and others 2011), and much darker biscuits due to added mango peels and seed kernels (Ashoush and Gadallah (2011). In addition, the Maillard reaction, together with the caramelization, is the main chemical event occurring during baking. The reaction occurs between the free amino group of lysine and other amino acids and the carbonyl groups of reducing sugars, leading to compounds responsible for the brown color of baked products (Capuano and others 2008) that also contributed to the darker color of the crackers. However, the color of samples determined by the sensory panel test (Table 4) was not significantly different between the majorities of samples, except for the sample nr 4 (with the addition of 40% hemp flour and no added green tea leaves). Similar findings for small changes in color between the samples are reported by Davidov-Pardo and others (2012) studying the cookies enriched with grape seed extracts. The prepared samples were very different in terms of physicochemical analysis. Water activity, as an indicator for microbiological stability, was below 0.60 in all samples. The low value for water activity indicated a potentially long shelf life at ambient temperature, without microbial spoilage for this snack that belongs to the low-moisture bakery products with aw < 0.6. Most low-moisture foods are designed to be storable for several months at room temperature and are shelf-stable (Smith and others 2004). Based on ANOVA analysis, total phenolic content and antioxidant activity of samples (Table 4) have shown significant differences depending on the amount of green tea leaves added (at P < 0.05). A significant difference was observed in terms of total phenols of 3.45 ± 0.09 mg GAE/g d.w. in sample nr 0 (where 8 g of green tea leaves added) and sample nr 4 (1.09 ± 0.18 mg GAE/g d.w.) with no addition of the green tea leaves. Similarly, the highest antioxidant activity was found in sample nr 0 (40.22 ± 1.42 μmol TE/g d.w.) and the lowest was found in the sample nr 4 (7.47 ± 1.61 μmol TE/g d.w.) with no addition of green tea leaves. In addition, hemp oil press-cake also contained phenols (TPC of 2.98 ± 0.05 mg GAE/ g d.w.) and had a high antioxidant activity (DPPH of 19.96 ± 0.53 μmol TE/g d.w.) that contributed to the Vol. 79, Nr. 3, 2014 r Journal of Food Science C321
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Hemp flour crackers with green tea . . .
Hemp flour crackers with green tea . . . Table 4–Physicochemical analysis, antioxidant properties, and sensory evaluation of gluten-free crackers. Parameter
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Hemp flour (%) Green tea leaves (g) Weight (g) Height (mm) Diameter (mm) Color L∗ a∗ b∗ Water activity TPC (mg GAE/g d.w.) DPPH (μmol TE/g d.w.) Sensory evaluation score Appearance Color Flavor Crunchiness Overall texture Overall score
Correlation r2
Sample
Sample
Sample
Sample
Sample
0 0 8 9.39 ± 0.12c 4.57 ± 0.03c 59.62 ± 0.31a
1 10 6 9.82 ± 0.22b 4.78 ± 0.04a 59.73 ± 0.54a
2 20 4 9.98 ± 0.07b 4.80 ± 0.04a 59.57 ± 0.56a
3 30 2 10.39 ± 0.14a 4.70 ± 0.02b 58.61 ± 0.24b
4 40 0 10.58 ± 0.21a 4.32 ± 0.04d 56.66 ± 0.27c
0.9330 0.9908 0.9921
46.47 ± 1.80a 6.12 ± 0.18a 16.65 ± 1.29a 0.55 ± 0.0a 3.45 ± 0.09a 40.22 ± 1.42a
45.42 ± 0.71a 4.13 ± 0.08b 14.78 ± 0.21a 0.39 ± 0.0b 2.75 ± 0.08b 33.67 ± 1.32b
40.47 ± 0.82b 4.39 ± 0.15b 11.60 ± 0.55b 0.42 ± 0.0b 2.65 ± 0.27c 31.19 ± 2.57c
37.34 ± 0.28c 4.42 ± 0.06b 9.25 ± 0.42b 0.51 ± 0.0a 2.03 ± 0.06d 22.43 ± 0.92d
33.84 ± 1.00d 4.33 ± 0.17b 6.05 ± 1.41c 0.56 ± 0.0a 1.09 ± 0.18e 7.47 ± 1.61e
0.9812 0.7519 0.9968 0.7764 0.9662 0.9811
7.9 ± 0.7bc 7.9 ± 0.7a 7.7 ± 0.8bc 8.2 ± 0.6a 7.7 ± 0.5b 8.6 ± 0.3bc
8.3 ± 0.5ab 8.1 ± 0.8a 8.2 ± 0.4ab 8.3 ± 0.5a 7.9 ± 0.5b 8.8 ± 0.3ab
8.8 ± 0.5a 8.5 ± 0.9a 8.8 ± 0.5a 8.6 ± 0.5a 8.7 ± 0.5a 9.0 ± 0.1a
8.5 ± 0.5ab 8.3 ± 0.6a 8.7 ± 0.5a 8.6 ± 0.5a 8.7 ± 0.5a 8.4 ± 0.3c
7.4 ± 0.9c 6.1 ± 0.9b 7.3 ± 074c 8.6 ± 0.5a 8.5 ± 0.5a 7.8 ± 0.2d
0.9221 0.8688 0.8810 0.9135 0.8623 0.7040
Values are means ± SD; n = 3. Means in the same row followed by different superscript letters are significantly different (P < 0.05).
Table 5–Proximate analysis, minerals, and fatty acids profile of gluten-free crackers. Per 100 g Parameter Hemp flour (%) Green tea leaves (g) Water content (%) Ash (%) Protein content (g) Fat content (g) Crude fibers (g) Carbohydrates (g) Minerals (mg) Ca Fe Mg Mn K Zn PUFA MUFA SAFA Linoleic acid (ω-6) α-Linolenic acid (ω-3) ω-6/ω-3 ratio
Sample
Sample
Sample
Sample
Sample
0 0 8 7.95 ± 0.12a 2.61 ± 0.09e 6.47 ± 0.3e 22.06 ± 0.08e 4.91 ± 0.10e 56.00 ± 0.22a
1 10 6 5.62 ± 0.03c 3.74 ± 0.08d 9.25 ± 0.28d 23.26 ± 0.12d 6.84 ± 0.12d 51.29 ± 0.15b
2 20 4 6.60 ± 0.43b 4.88 ± 0.10c 11.51 ± 0.37c 23.71 ± 0.15c 8.59 ± 0.10c 44.91 ± 0.13c
3 30 2 6.69 ± 0.10b 5.92 ± 0.10b 14.11 ± 0.26b 24.34 ± 0.11b 10.46 ± 0.11b 38.48 ± 0.22d
4 40 0 7.34 ± 0.26a 6.81 ± 0.13a 16.40 ± 0.40a 24.86 ± 0.09a 12.26 ± 0.10a 32.33 ± 0.14e
64.04 ± 0.17e 1.11 ± 0.03e 5.67 ± 0.12e 1.21 ± 0.07e 145.54 ± 0.52e 1.47 ± 0.08b 7.62 ± 0.10e 10.73 ± 0.10b 1.89 ± 0.08a 4.73 ± 0.78e 2.89 ± 0.09c 1.66c
72.46 ± 0.15d 1.56 ± 0.07d 17.96 ± 0.10d 1.66 ± 0.07d 166.82 ± 0.32d 1.55 ± 0.06ab 8.35 ± 0.09d 11.17 ± 0.08a 1.99 ± 0.06a 5.25 ± 0.10d 3.09 ± 0.09bc 1.7bc
78.47 ± 0.12c 1.99 ± 0.07c 29.97 ± 0.10c 2.09 ± 0.08c 182.79 ± 0.55c 1.59 ± 0.04ab 8.83 ± 0.12c 11.24 ± 0.11a 2.01 ± 0.08a 5.59 ± 0.10c 3.19 ± 0.10ab 1.75ab
85.24 ± 0.11b 2.38 ± 0.07b 42.27 ± 0.38b 2.56 ± 0.07b 199.73 ± 0.38b 1.64 ± 0.05b 9.33 ± 0.13b 11.35 ± 0.11a 2.05 ± 0.08a 5.93 ± 0.08b 3.35 ± 0.10ab 1.77ab
91.78 ± 0.58a 2.85 ± 0.08a 54.65 ± 0.41a 3.01 ± 0.08a 216.21 ± 0.33a 1.68 ± 0.07a 9.84 ± 0.98a 11.42 ± 0.08a 2.09 ± 0.08a 6.3 ± 0.108a 3.45 ± 0.11a 1.83a
PUFA—polyunsaturated fatty acids; MUFA—monounsaturated fatty acids; SAFA—saturated fatty acids. Values are means ± SD; n = 3. Means in the same row followed by different superscript letters are significantly different (P < 0.05).
overall value of the crackers. Norajit and others (2011) studied the effects of defatted hemp flour at 20%, 30%, and 40% levels (based on the rice flour) on the physicochemical properties of extruded rice. Their results for the protein content of the extruded snack are in agreement with our results, while the ash content is slightly lower than in our samples. Total phenolic content of their samples was lower for samples with 20% and 30% hemp flour replacement compared to what was determined in our crackers. Davidov-Pardo and others (2012) found that the antioxidant activity of cookies enriched with grape seed extracts was high at 7.8 ± 0.1 μmol /g. Our crackers had up to 8 times higher antioxidant activity (sample nr 0—with the addition of 8 g of green tea leaves) than their
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sample. In addition, our results of total phenolic content are comparable to the study of gluten-free crackers based on buckwheat flour by Sedej and others (2011). What was also interesting in the study of Davidov-Pardo and others (2012) was the fact based on their consumers’ study: if provided with the health benefits information and functionality of antioxidants in the cookies, 60% of consumers stated that they were willing to purchase cookies enriched with antioxidants. Sensory evaluation in our study confirmed that crackers were successfully developed to be tasty, crunchy, and indicative to contain green tea because of the intensive green color of the crackers. Appearance, color, and flavor were slightly different among all samples, except
for the sample nr 4 (with the addition of 40% hemp flour and addition of green tea leaves) that was much darker and received the lowest sensory score (7.8±0.2) and considered as “unacceptable.” Two samples: nr 1 (with the addition of 10% hemp flour and 6 g of green tea leaves) and sample nr 2 (with the addition of 20% hemp flour and 4 g of green tea leaves) were described to have a very pleasant, nutty flavor, “healthy” appearance and a very distinctive crunchiness. Sample nr 2 (with the addition of 20% hemp flour and 4 g of decaffeinated green tea leaves) was voted as the best sample; ready to proceed with a consumer’s study. Once the sensory evaluation was completed, the crackers’ formulations were revealed to the panel. Because of the enrichment with the decaffeinated green tea leaves as antioxidants, as well as much more favorable nutritional profile due to the added hemp flour, the sensory panel was unanimous in their decision to purchase those crackers if available. Proximate analysis of all samples is presented in Table 5. The ash content was significantly different in all samples, and as expected, progressively rose with an increase in the amount of added hemp flour, which was rich in minerals (Table 5). The fat, that is, oil content of the samples was high due to canola oil and chia seeds use. However, canola oil is known to have high polyunsaturated fatty acids (PUFAs) content along with the alpha-linolenic fatty acid (Radoˇcaj and Dimi´c 2013). Crackers were high in monounsaturated fatty acids (MUFAs) as well as PUFAs. The saturated fatty acids (SAFAs) content was very low in all crackers (1.89 ± 0.08 g/100 g to 2.09±0.08 g/100 g) (Table 5). The protein content was the highest in the sample nr 4 (16.40 ± 0.40 g/100 g) (with the addition of 10% hemp flour and 6 g of green tea leaves), and it was high in samples nr 2 (11.51 ± 0.37 g/100 g) (with the addition of 20% hemp flour and 4 g of green tea leaves) and nr 3 (14.11±0.26 g/100 g) (with the addition of 30% hemp flour and 2 g of green tea leaves). The addition of hemp flour caused a significant fiber content increase of all samples (6.84 ± 0.12 to 12.26 ± 0.03 g/100 g) compared to the brown rice flour sample (6.47±0.30 g/100 g). The increase in
the proteins, total fibers, minerals, and essential fatty acids content suggests that a new product has better nutritional characteristics than the sample without added hemp flour. Gluten-free crackers developed by Han and others (2010) using pulse flours had a much lower level of proteins, fibers, and minerals than our crackers. Their samples did not contain any essential fatty acids. The content of omega-6 increased significantly (at P < 0.05) with the addition of hemp flour. The omega-3 fatty acids content was lowest in the sample without hemp flour (2.89 ± 0.09 g/100 g) and the highest in the sample nr 4 (with the addition of 40% hemp flour and no added green tea leaves), which was not significantly different from the omega-3 fatty acids content in samples nr 2 (with the addition of 20% hemp flour and 4 g of green tea leaves) and 3 (with the addition of 30% hemp flour and 2 g of green tea leaves). Imbalances in the intake of omega-6 and omega-3 fatty acids are associated with various diseases. A lower ratio of omega-6/omega3 fatty acids, such as 2 to 3 : 1, is more desirable in reducing the risk of many chronic diseases in Western society, in which a diet is deficient in omega−3 fatty acids and has excessive amounts of omega−6 fatty acids, compared to the diet on which human beings evolved (Simopoulos 2002a; Strandvik 2011). Today, in Western diets, the ratio of omega-6 to omega-3 fatty acids ranges from 10 to 20 : 1 instead of the traditional range of 1 to 2 : 1. Studies indicate that a high intake of omega-6 fatty acids shifts the physiologic state to one that is prothrombotic and proaggregatory, characterized by increases in blood viscosity, vasospasm, and vasoconstriction and decreases in bleeding time, whereas omega-3 fatty acids have antiinflammatory, antithrombotic, antiarrhythmic, hypolipidemic, and vasodilatory properties (Simopoulos 2002b). An extensive study of various cold-pressed oils (Radoˇcaj and Dimi´c 2013) has shown that hemp oil had not only the high content of omega-6 and omega-3 fatty acids, but also that their ratio was well balanced (3.1). In all prepared crackers, the content of omega-6 and omega-3 fatty acids was perfectly balanced, as their ratio was 1.66 to 1.83 among the samples (Table 5).
Figure 1–Appearance of gluten-free crackers based on hemp oil press-cake and brown rice flour with the addition of decaffeinated green tea leaves.
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Hemp flour crackers with green tea . . .
Hemp flour crackers with green tea . . .
C: Food Chemistry
All samples had significant amounts of calcium, iron, magnesium, manganese, potassium, and zinc. For example, a study (de Oliveira and others 2009) of gluten-free cookies enriched with guarana and catuba plants to achieve higher contents of copper, iron, and zinc demonstrated that their cookies had iron present at 4.50 ± 0.34 mg/100 g and zinc at 1.32 ± 0.09 mg/100 g, which compared to our crackers, were higher in iron, but lower in zinc (Table 5). In terms of the use of hemp oil press-cake flour, the carbohydrate content reduction, along with the proteins, essential fatty acids, minerals, and fiber content increase, was a main goal of this study in terms of improving the nutritional profile of the gluten-free crackers. Likewise, increasing the total phenols and antioxidant properties of crackers by usage of decaffeinated green tea leaves was also successfully accomplished. The correlation coefficients between the amount of added hemp oil press-cake, decaffeinated green tea leaves, and some product variables are presented in Table 4. This table shows that there was a significant correlation between the amount of added ingredients and physicochemical attributes, such as weight, height, diameter, color, and water activity. Also, total phenolic content and antioxidant activities were highly correlated to the addition of hemp flour and decaffeinated green tea leaves. There was a very significant positive correlation between the added green tea leaves and total phenolic content (r = 0.9710 at P < 0.05), and between the added hemp flour and total phenolic content (r = 0.944 at P < 0.05). Optimization of the responses was conducted using the same software as explained earlier, based on the maximized values for protein, fibers, omega-3 fatty acids content, as well as for the antioxidant activity and overall score. The suggested values for the addition of the hemp oil press-cake was 20% with 4 g of decaffeinated green tea leaves that would provide protein content of 14.1 g/100 g; fibers content of 8.4 g/100 g; omega-3 fatty acids content of 3.2 g/100 g; antioxidant activity measured via DPPH value of 30.3 μmol TE/g d.w.; and an overall score of 8.9. The recommendation based on this study is that hemp flour (hemp oil press-cake) may be used as a functional ingredient in the formulation of a cracker based on the brown rice flour and that these crackers had enhanced nutritional quality, as it was also concluded by Norajit and others (2011) in extruded rice/hemp product.
Conclusions A functional gluten-free food product was developed to broaden consumers’ choices in this segment of value added products. This study was an attempt to incorporate highly nutritious hemp flour, as a by-product of the cold-pressed hemp oil (functional ingredient) in combination with decaffeinated green tea leaves, in a portable snack type cracker. Based on our research, it was suggested that hemp oil press-cake may be a good and original source for crackers development, which enables valorization of this byproduct (that is generally considered as a waste) in other food applications. A brown rice flour cracker can be enriched with hemp flour by up to 30% and green tea leaves by 8 g in order to increase the total proteins, fibers, essential fatty acids, mineral content, as well as total phenolic and antioxidant activity, thereby providing a value-added, healthier snack, compared to the brown rice flour cracker. The enrichment caused a significant change in the physicochemical profile of the prepared samples, and the sensory evaluation by the panel. Samples nr 1 (hemp flour addition of 10% and green tea leaves of 6 g) and nr 2 (hemp flour addition of 20% and green tea leaves of 4 g) had the highest sensory score (8.8 and C324 Journal of Food Science r Vol. 79, Nr. 3, 2014
9.0, respectively). They achieved an increase in the total fibers (for about 43% and 78%, respectively) and protein content (for about 40% and 87%, respectively), compared to the brown rice flour cracker. For samples nr 1 and 2, the addition of the decaffeinated green tea leaves provided very high radical scavenging (antioxidant) activity of 33.67 ± 1.32 μmol TE/g d.w. and 31.19 ± 2.57 μmol TE/g d.w., respectively. The optimized cracker formulations would be with 20% hemp flour and 4 g of decaffeinated green tea leaves incorporated into the dough formula.
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Hemp flour crackers with green tea . . .
