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Food Additives & Contaminants: Part B: Surveillance Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfab20
Aluminium content of some processed foods, raw materials and food additives in China by inductively coupled plasma–mass spectrometry a
b
a
b
b
Gui-Fang Deng , Ke Li , Jing Ma , Fen Liu , Jing-Jing Dai & Hua-Bin Li
a
a
Guangdong Provincial Key Laboratory of Food , Nutrition and Health, School of Public Health, Sun Yat-Sen University , Guangzhou 510080, China b
Futian District Center for Disease Prevention and Control , Shenzhen 518040, China Accepted author version posted online: 19 Oct 2011.Published online: 29 Nov 2011.
To cite this article: Gui-Fang Deng , Ke Li , Jing Ma , Fen Liu , Jing-Jing Dai & Hua-Bin Li (2011) Aluminium content of some processed foods, raw materials and food additives in China by inductively coupled plasma–mass spectrometry, Food Additives & Contaminants: Part B: Surveillance, 4:4, 248-253, DOI: 10.1080/19393210.2011.632899 To link to this article: http://dx.doi.org/10.1080/19393210.2011.632899
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Food Additives and Contaminants: Part B Vol. 4, No. 4, December 2011, 248–253
Aluminium content of some processed foods, raw materials and food additives in China by inductively coupled plasma–mass spectrometry Gui-Fang Dengay, Ke Liby, Jing Maa*, Fen Liub, Jing-Jing Daib and Hua-Bin Lia a Guangdong Provincial Key Laboratory of Food, Nutrition and Health, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; bFutian District Center for Disease Prevention and Control, Shenzhen 518040, China
Downloaded by [New York University] at 12:33 29 May 2015
(Received 15 August 2011; final version received 12 October 2011) The level of aluminium in 178 processed food samples from Shenzhen city in China was evaluated using inductively coupled plasma–mass spectrometry. Some processed foods contained a concentration of up to 1226 mg/kg, which is about 12 times the Chinese food standard. To establish the main source in these foods, Al levels in the raw materials were determined. However, aluminium concentrations in raw materials were low (0.10–451.5 mg/kg). Therefore, aluminium levels in food additives used in these foods was determined and it was found that some food additives contained a high concentration of aluminium (0.005–57.4 g/kg). The results suggested that, in the interest of public health, food additives containing high concentrations of aluminium should be replaced by those containing less. This study has provided new information on aluminium levels in Chinese processed foods, raw materials and a selection of food additives. Keywords: aluminium; processed foods
Introduction Aluminium (Al) is a ubiquitous element but its impact on biological systems has been subject of much controversy over the past decades (Campbell and Bondy 2000). Research has revealed that aluminium is toxic to humans and associated with significant central nervous system toxicity and bone and liver damage (Ganrot 1986; Nayak and Chatterjee 2000; Yokel 2000; Kumar and Gill 2009; Poole et al. 2010). Other studies have correlated high Al content in human tissues with the occurrence of certain neurodegenerative disorders, such as Alzheimer’s disease, Parkinson’s disease and encephalopathies (Bertholf et al. 1988; Flattens 1990; Storey and Masters 1995). Moreover, the impact of aluminium on the extraneural system, such as musculoskeletal, cardiovascular, hepatobiliary, endocrine, blood and hemopoietic systems, has been reported (Birchall 1991; Kerr et al. 1992; Garay et al. 1996; Demircan et al. 1998; Verma et al. 1999). Although there are several potential routes of exposure to Al, such as environmental, dietary, iatrogenic and occupational; for consumers, diet is the main source of Al intake (Nayak 2002). Drinking water and beverages are minor contributors. Food is the main source of aluminium intake because unprocessed food could be polluted by soil, water and air contaminated
*Corresponding author. Email: [email protected] yThese authors equally contributed to this paper. ISSN 1939–3210 print/ISSN 1939–3229 online ß 2011 Taylor & Francis http://dx.doi.org/10.1080/19393210.2011.632899 http://www.tandfonline.com
with aluminium. Al in processed food might also come from processing, packaging material, additives or cookware (FDA/WHO 1989; Fairweather-Tait et al. 1994; Seruga et al. 1994; Pennington and Schoen 1995; Muller et al. 1998). Therefore, it is necessary to monitor the content of Al in food. Information with regard to the Al content of foodstuffs in several countries is available (Pennington and Schoen 1995; Gramiccioni et al. 1996; Neelam and Kaladhar 2000; Ysart et al. 2000; Jalbani et al. 2007; Gonzalez-Weller et al. 2010), but no data on the Al content of foods in China could be found. Shenzhen, a city adjacent to Hong Kong and in a rapidly developing economic region of China, has attracted many people from Hong Kong, other provinces of China, as well as from many other countries. Food sold in Shenzhen comes from different regions and could be considered as typically representative of food from all China. Thus, it is very important to monitor the quality of food sold in Shenzhen. When the levels of aluminium in food samples were evaluated in our laboratory, it was found that some contained high concentration of aluminium (up to 1226 mg/kg), which is about 12 times of the food standard of China (100 mg/kg). To find out the main source of aluminium, its content in raw materials was determined.
Food Additives and Contaminants: Part B However, the aluminium content was low in the raw materials, with a maximum of 451.5 mg/kg. Thereafter, aluminium content in food additives used for these foods was determined and it was found that some of them contained high concentrations of aluminium, with a maximum value of 57.4 g/kg. This paper supplied new information on aluminium content in a variety of foods and their raw materials as well as in some food additives in China.
Downloaded by [New York University] at 12:33 29 May 2015
Materials and methods Reagents Aluminium nitrate and scandium nitrate were analytical grade and Chinese standard reference materials (National Center for Standard Reference Materials, Beijing, China). Chromazurine S, cirrasol OD, acetic acid, sodium acetate, nitric acid, hydrogen peroxide and ascorbic acid were of analytical reagent grade and obtained from Shanghai Chemical Reagent Company (Shanghai, China). Deionised water, obtained from a Milli-Q water purification system (Millipore, CA, USA) was used throughout the experiment. Stock solutions of aluminium nitrate and scandium nitrate (10 mg/ml) were prepared with 0.16 mol/l nitric acid and stored at 4 C. The calibration standard of aluminium nitrate (10–2000 ng/ml) was prepared from the stock solution by serial dilution of 0.16 mol/l nitric acid. The working solution of 1.0 mg/ml scandium nitrate was prepared in a similar way.
Sample preparation A total of 296 samples was collected from 74 catering establishments in Shenzhen, including 178 processed food samples, 55 samples of raw materials and 63 samples of food additives. Samples were ground to powder in a IKA WERKE-M20 knife mill (IKA, Staufen, Germany) and dried in an oven at 85 C for 4 h. Thereafter, they were stored in refrigerators at 4 C until they were analysed. A 0.5-g portion for inductively coupled plasmamass spectrometry and a 2-g sample for spectrophotometry was accurately weighed and transferred into a capped PTFE vessel, and mixed with 3 ml of 65% nitric acid and 2 ml of 30% hydrogen peroxide. Digestion was carried out in a Milestone Ethos 1 microwave device (Sorisole, Italy). The temperature was ramped to 200 C within 10 min, followed by a dwell-time of 15 min under microwave irradiation at 1000 W. After completion, the vessel was taken out to cool to room temperature. The sample solution was transferred to a volumetric flask and diluted to 50 ml with water.
249
Analytical methods Inductively coupled plasma-mass spectrometry Aluminium in the sample was determined by inductively coupled plasma–mass spectrometry (Thermo XS series 2; Agilent, Lexington, MA, USA) according to the standard method of China (MHC 2009). Typical operating conditions and instrumental parameters employed in this study were: forward power 1357 W; analogue detector 1784 V; PC detector 3265 V; sampling depth 135 mm; cool gas 13.0 l/min Ar; auxiliary gas 0.72 l/min Ar; extraction 125.5 V. Spectrophotometry Al in the sample was determined by a Shimadzu UV-2550 spectrophotometry (Kyoto, Japan) according to the standard method of China (MHC 2003). In principle, 1.00 ml sample solution was placed in a capped glass tube and then mixed with 8.00 ml of acetic acid/sodium acetate buffer (0.3 mol/l, pH 6.0), 1.00 ml of ascorbic acid solution (10 g/l), 2.00 ml of cirrasol OD solution (0.20 g/l) and 2.00 ml of Chromazurine S solution (0.50 g/l). The mixture was diluted to 50.00 ml with water. After 20 min, absorbance of the solution was measured at 640 nm, and the content of Al in the sample was calculated from the standard curve. Statistics All experiments were conducted in triplicate and average values are reported. The results were calculated using Microsoft Excel software. Statistical analyses were conducted using the SPSS version 10.0 statistical analysis packages (SPSS Inc., Chicago, IL, USA). Differences were considered significant at p 5 0.05.
Results and discussion Choice of analytical method In the literature, several methods have been developed for the determination of Al in food, such as spectrophotometry (Onianwa et al. 1997), atomic absorption spectrometry (Muller et al. 1998; Jalbani et al. 2007), inductively coupled plasma–optical emission spectrometry (Fung et al. 2009) and inductively coupled plasma–mass spectrometry (Millour et al. 2011). Spectrophotometry and inductively coupled plasma– mass spectrometry are Chinese standard methods for the determination of Al in food. These two methods were compared and the results are shown in Tables 1 and 2. A homogeneity of variance test demonstrated that total variances of the results obtained by these two methods are equal, and statistical analysis of variance indicated that there is no significant difference between both methods (F ¼ 0.017, p ¼ 0.879, ¼ 0.05). As can
250
G.-F. Deng et al.
be seen from Table 1, inductively coupled plasma–mass spectrometry has more advantages than spectrophotometry. Therefore, it was chosen as an analytical method of choice for the determination of Al in the subsequent study.
The levels of aluminium in all 178 processed food samples can be found in the database and summarised in Table 3. Levels of Al in processed foods varied from nd (not detected) to 1226 mg/kg, which is about 12 times the Chinese food standard of 100 mg/kg. Considerable variation in Al content was also observed within the same type of processed food. Figure 1 shows the frequency distribution, where only 56.1% of the processed foods met the Chinese standard (100 mg/kg). For steamed sponge cake, this percentage was the lowest at only 27.3% (Figure 2). The weight of the product package was taken as the portion size, even when, in some cases, it cannot be assumed that the
Aluminium content in raw materials Some processed foods contained high levels of Al, which could come from processing, packaging material, cookware, drinking water, food additives or the raw material (Greger et al. 1985; Pennington 1988;
70 60 50
Table 1. Comparison of ICP–MS and spectrophotometry for the determination of Al. Parameters
ICP–MS
Spectrophotometry
Limit of detection (mg/l) Linear range (mg/l) Recovery (%) Relative standard deviation (%)
0.12 10–2000 95.0–99.0 1.2–2.2
10 10–120 91.0–95.2 1.9–2.2
Frequency
Downloaded by [New York University] at 12:33 29 May 2015
Aluminium content in processed food
whole portion was eaten by one person all at once. As can be seen from Table 3, eating 100 g of the steamed food or twisted cruller results in an Al intake ranging from 17.6 to 35.4 mg. Actually, most adult males consume more than 100 g of the steamed food or twisted cruller per day. This Al intake could be higher than that reported by Greger (1985), who estimated that a 25–30-year-old man took in about 198 g cereals per day and, accordingly, 18.4 mg Al per day, on average.
40 30 20 10 0
Food Additives & Contaminants: Part B: Surveillance Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfab20
Aluminium content of some processed foods, raw materials and food additives in China by inductively coupled plasma–mass spectrometry a
b
a
b
b
Gui-Fang Deng , Ke Li , Jing Ma , Fen Liu , Jing-Jing Dai & Hua-Bin Li
a
a
Guangdong Provincial Key Laboratory of Food , Nutrition and Health, School of Public Health, Sun Yat-Sen University , Guangzhou 510080, China b
Futian District Center for Disease Prevention and Control , Shenzhen 518040, China Accepted author version posted online: 19 Oct 2011.Published online: 29 Nov 2011.
To cite this article: Gui-Fang Deng , Ke Li , Jing Ma , Fen Liu , Jing-Jing Dai & Hua-Bin Li (2011) Aluminium content of some processed foods, raw materials and food additives in China by inductively coupled plasma–mass spectrometry, Food Additives & Contaminants: Part B: Surveillance, 4:4, 248-253, DOI: 10.1080/19393210.2011.632899 To link to this article: http://dx.doi.org/10.1080/19393210.2011.632899
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Food Additives and Contaminants: Part B Vol. 4, No. 4, December 2011, 248–253
Aluminium content of some processed foods, raw materials and food additives in China by inductively coupled plasma–mass spectrometry Gui-Fang Dengay, Ke Liby, Jing Maa*, Fen Liub, Jing-Jing Daib and Hua-Bin Lia a Guangdong Provincial Key Laboratory of Food, Nutrition and Health, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; bFutian District Center for Disease Prevention and Control, Shenzhen 518040, China
Downloaded by [New York University] at 12:33 29 May 2015
(Received 15 August 2011; final version received 12 October 2011) The level of aluminium in 178 processed food samples from Shenzhen city in China was evaluated using inductively coupled plasma–mass spectrometry. Some processed foods contained a concentration of up to 1226 mg/kg, which is about 12 times the Chinese food standard. To establish the main source in these foods, Al levels in the raw materials were determined. However, aluminium concentrations in raw materials were low (0.10–451.5 mg/kg). Therefore, aluminium levels in food additives used in these foods was determined and it was found that some food additives contained a high concentration of aluminium (0.005–57.4 g/kg). The results suggested that, in the interest of public health, food additives containing high concentrations of aluminium should be replaced by those containing less. This study has provided new information on aluminium levels in Chinese processed foods, raw materials and a selection of food additives. Keywords: aluminium; processed foods
Introduction Aluminium (Al) is a ubiquitous element but its impact on biological systems has been subject of much controversy over the past decades (Campbell and Bondy 2000). Research has revealed that aluminium is toxic to humans and associated with significant central nervous system toxicity and bone and liver damage (Ganrot 1986; Nayak and Chatterjee 2000; Yokel 2000; Kumar and Gill 2009; Poole et al. 2010). Other studies have correlated high Al content in human tissues with the occurrence of certain neurodegenerative disorders, such as Alzheimer’s disease, Parkinson’s disease and encephalopathies (Bertholf et al. 1988; Flattens 1990; Storey and Masters 1995). Moreover, the impact of aluminium on the extraneural system, such as musculoskeletal, cardiovascular, hepatobiliary, endocrine, blood and hemopoietic systems, has been reported (Birchall 1991; Kerr et al. 1992; Garay et al. 1996; Demircan et al. 1998; Verma et al. 1999). Although there are several potential routes of exposure to Al, such as environmental, dietary, iatrogenic and occupational; for consumers, diet is the main source of Al intake (Nayak 2002). Drinking water and beverages are minor contributors. Food is the main source of aluminium intake because unprocessed food could be polluted by soil, water and air contaminated
*Corresponding author. Email: [email protected] yThese authors equally contributed to this paper. ISSN 1939–3210 print/ISSN 1939–3229 online ß 2011 Taylor & Francis http://dx.doi.org/10.1080/19393210.2011.632899 http://www.tandfonline.com
with aluminium. Al in processed food might also come from processing, packaging material, additives or cookware (FDA/WHO 1989; Fairweather-Tait et al. 1994; Seruga et al. 1994; Pennington and Schoen 1995; Muller et al. 1998). Therefore, it is necessary to monitor the content of Al in food. Information with regard to the Al content of foodstuffs in several countries is available (Pennington and Schoen 1995; Gramiccioni et al. 1996; Neelam and Kaladhar 2000; Ysart et al. 2000; Jalbani et al. 2007; Gonzalez-Weller et al. 2010), but no data on the Al content of foods in China could be found. Shenzhen, a city adjacent to Hong Kong and in a rapidly developing economic region of China, has attracted many people from Hong Kong, other provinces of China, as well as from many other countries. Food sold in Shenzhen comes from different regions and could be considered as typically representative of food from all China. Thus, it is very important to monitor the quality of food sold in Shenzhen. When the levels of aluminium in food samples were evaluated in our laboratory, it was found that some contained high concentration of aluminium (up to 1226 mg/kg), which is about 12 times of the food standard of China (100 mg/kg). To find out the main source of aluminium, its content in raw materials was determined.
Food Additives and Contaminants: Part B However, the aluminium content was low in the raw materials, with a maximum of 451.5 mg/kg. Thereafter, aluminium content in food additives used for these foods was determined and it was found that some of them contained high concentrations of aluminium, with a maximum value of 57.4 g/kg. This paper supplied new information on aluminium content in a variety of foods and their raw materials as well as in some food additives in China.
Downloaded by [New York University] at 12:33 29 May 2015
Materials and methods Reagents Aluminium nitrate and scandium nitrate were analytical grade and Chinese standard reference materials (National Center for Standard Reference Materials, Beijing, China). Chromazurine S, cirrasol OD, acetic acid, sodium acetate, nitric acid, hydrogen peroxide and ascorbic acid were of analytical reagent grade and obtained from Shanghai Chemical Reagent Company (Shanghai, China). Deionised water, obtained from a Milli-Q water purification system (Millipore, CA, USA) was used throughout the experiment. Stock solutions of aluminium nitrate and scandium nitrate (10 mg/ml) were prepared with 0.16 mol/l nitric acid and stored at 4 C. The calibration standard of aluminium nitrate (10–2000 ng/ml) was prepared from the stock solution by serial dilution of 0.16 mol/l nitric acid. The working solution of 1.0 mg/ml scandium nitrate was prepared in a similar way.
Sample preparation A total of 296 samples was collected from 74 catering establishments in Shenzhen, including 178 processed food samples, 55 samples of raw materials and 63 samples of food additives. Samples were ground to powder in a IKA WERKE-M20 knife mill (IKA, Staufen, Germany) and dried in an oven at 85 C for 4 h. Thereafter, they were stored in refrigerators at 4 C until they were analysed. A 0.5-g portion for inductively coupled plasmamass spectrometry and a 2-g sample for spectrophotometry was accurately weighed and transferred into a capped PTFE vessel, and mixed with 3 ml of 65% nitric acid and 2 ml of 30% hydrogen peroxide. Digestion was carried out in a Milestone Ethos 1 microwave device (Sorisole, Italy). The temperature was ramped to 200 C within 10 min, followed by a dwell-time of 15 min under microwave irradiation at 1000 W. After completion, the vessel was taken out to cool to room temperature. The sample solution was transferred to a volumetric flask and diluted to 50 ml with water.
249
Analytical methods Inductively coupled plasma-mass spectrometry Aluminium in the sample was determined by inductively coupled plasma–mass spectrometry (Thermo XS series 2; Agilent, Lexington, MA, USA) according to the standard method of China (MHC 2009). Typical operating conditions and instrumental parameters employed in this study were: forward power 1357 W; analogue detector 1784 V; PC detector 3265 V; sampling depth 135 mm; cool gas 13.0 l/min Ar; auxiliary gas 0.72 l/min Ar; extraction 125.5 V. Spectrophotometry Al in the sample was determined by a Shimadzu UV-2550 spectrophotometry (Kyoto, Japan) according to the standard method of China (MHC 2003). In principle, 1.00 ml sample solution was placed in a capped glass tube and then mixed with 8.00 ml of acetic acid/sodium acetate buffer (0.3 mol/l, pH 6.0), 1.00 ml of ascorbic acid solution (10 g/l), 2.00 ml of cirrasol OD solution (0.20 g/l) and 2.00 ml of Chromazurine S solution (0.50 g/l). The mixture was diluted to 50.00 ml with water. After 20 min, absorbance of the solution was measured at 640 nm, and the content of Al in the sample was calculated from the standard curve. Statistics All experiments were conducted in triplicate and average values are reported. The results were calculated using Microsoft Excel software. Statistical analyses were conducted using the SPSS version 10.0 statistical analysis packages (SPSS Inc., Chicago, IL, USA). Differences were considered significant at p 5 0.05.
Results and discussion Choice of analytical method In the literature, several methods have been developed for the determination of Al in food, such as spectrophotometry (Onianwa et al. 1997), atomic absorption spectrometry (Muller et al. 1998; Jalbani et al. 2007), inductively coupled plasma–optical emission spectrometry (Fung et al. 2009) and inductively coupled plasma–mass spectrometry (Millour et al. 2011). Spectrophotometry and inductively coupled plasma– mass spectrometry are Chinese standard methods for the determination of Al in food. These two methods were compared and the results are shown in Tables 1 and 2. A homogeneity of variance test demonstrated that total variances of the results obtained by these two methods are equal, and statistical analysis of variance indicated that there is no significant difference between both methods (F ¼ 0.017, p ¼ 0.879, ¼ 0.05). As can
250
G.-F. Deng et al.
be seen from Table 1, inductively coupled plasma–mass spectrometry has more advantages than spectrophotometry. Therefore, it was chosen as an analytical method of choice for the determination of Al in the subsequent study.
The levels of aluminium in all 178 processed food samples can be found in the database and summarised in Table 3. Levels of Al in processed foods varied from nd (not detected) to 1226 mg/kg, which is about 12 times the Chinese food standard of 100 mg/kg. Considerable variation in Al content was also observed within the same type of processed food. Figure 1 shows the frequency distribution, where only 56.1% of the processed foods met the Chinese standard (100 mg/kg). For steamed sponge cake, this percentage was the lowest at only 27.3% (Figure 2). The weight of the product package was taken as the portion size, even when, in some cases, it cannot be assumed that the
Aluminium content in raw materials Some processed foods contained high levels of Al, which could come from processing, packaging material, cookware, drinking water, food additives or the raw material (Greger et al. 1985; Pennington 1988;
70 60 50
Table 1. Comparison of ICP–MS and spectrophotometry for the determination of Al. Parameters
ICP–MS
Spectrophotometry
Limit of detection (mg/l) Linear range (mg/l) Recovery (%) Relative standard deviation (%)
0.12 10–2000 95.0–99.0 1.2–2.2
10 10–120 91.0–95.2 1.9–2.2
Frequency
Downloaded by [New York University] at 12:33 29 May 2015
Aluminium content in processed food
whole portion was eaten by one person all at once. As can be seen from Table 3, eating 100 g of the steamed food or twisted cruller results in an Al intake ranging from 17.6 to 35.4 mg. Actually, most adult males consume more than 100 g of the steamed food or twisted cruller per day. This Al intake could be higher than that reported by Greger (1985), who estimated that a 25–30-year-old man took in about 198 g cereals per day and, accordingly, 18.4 mg Al per day, on average.
40 30 20 10 0
