International Journal of Food Microbiology, 13 (1991) 81-86 © 1991 Elsevier Science Publishers B.V. 0168-1605/91/$03.50
81
FOOD 00399
Short c o m m u n i c a t i o n
Inhibitory and stimulatory effects of cumin, oregano and their essential oils on growth and acid production of Lactobacillus plantarum and Leuconostoc mesenteroides Merih Kavan~ ~, Attila Akgtil 2 and Ayten Dogan
3
I Biology Department, Facultyo/Sciences andArts, Anadolu University, Eskqehir, and : Food Science and TcchnoloD, Department, Facultyof Agriculture, Atat~k University, Erzurum, and 3 Food Science and T e c h ~ ~ Facultyo/Agriculture, Ankara Umvcesity, Dqkapt.Ankara, Turkey (Received 12 Match 1990; accepted 8 January 1991)
Cumin at concentrations of 0.5, 1.0 and 2.0 q~ (w/w) stimulated growth and acid production of /..~t~ p/m~aram and Lz,tg'o,w~oc m e a m t ~ in a liquid medium. Essential oil from cumin at Irish conceatratio~ (300 and 600 ppm) inhibited growth and acid production of Laaobaci//a~ p/aataram. Aftra" a ¢s~tain period, growth of ~ o ¢ mc.g,ntermdcs was observed at all concentrations (150, 300 and 600 ppm) and its acid production was stimulated at 600 ppm. Oregano and its esseatial oil at all concentrations inhibited growth of both cultures. Acid production by Lactobacillus plantarum was stimulated by oreilam~ spice. Key words: Spice; Essemial oil; Lactic acid bacteria; Inhibitory effect: Stimulatory effect
Introduction Most of the studies reported on the antimicrobial activity of spices and essential oils involved pathogenic or spoilage microorganisms, and a few reports on starter cultures e.g. lactic acid bacteria are available (SheleL 1983; Janssen et al., 1987). These reports suggest that lactic acid bacteria are relatively resistant to the toxic effects of spices or essential oils. Furthermore, some spices have been shown to exert a stimulatory effect on these organisms, which resulted in enhanced growth and/or acid production (Karaioannoglou et al., 1977; Shelef et al., 1980; Tiwari and Pandey, 1981). Effects of spices on starter cultures used in fermentation of meat products has been investigated. Lactobacillus plantarum was found to be stimulated by spices, and the effect appeared to be associated with the natural spices rather than with Correspondence (Present) m/dress: A. Akffll, Zirsutt Fak.. $el~k 0niv., 42049 Konya. Tlirkiye.
82 their oleoresins (Nes and Skjeivale, 1982). A mixture of some spices enhanced fermentation of Lebanon bologna sausages (Zaika et al., 1978: K.issinger and Zaika. 1978; Zaika and Kissinger, 1979). It has been reported that rmcroorganisms can develop resistance towards inhibiting effects by spices (Zaika and Kissinger. 1981: Zaika et al., !983). In the present study the influence of two Turkish spices, cumin fruits and oregano leaves, and their essential oils were tested on Lactobacillus plamarum and Leuconoswc mesemeroides, in a liquid medium. These spices are commonly used in various fermented food products.
Materials and Methods
Cultures of Lactobacillus planmrum NRRL B-4496 and Leuconostoc mesenteroides NRRL B-512F (from USDA, Agriculture Research Service, Peoria, IL) were used throughout the study. According to the supplier, these are single-strain cultures. Cumin (Cuminum cyrmnum L.) dried fruits and oregano (Origanum onites L) dried leaves and oils were commercially produced. The oil yields were 3.0 and 3.1~ (v/w) respectively. The fermentation medium was prepared by dissolving 3 g beef extract (Difco), 5 g tryptone (Difco), 20 g sucrose and 20 g glucose in 1 1 of distilled water. The pH of the medium was adjusted to 6.5 with 6N H2SO4. Aliquots of the medium were dispensed into Erlenmeyer flasks, and heat-sterilized. The appropriate levels of spices were added before the sterilization. Duplicate flasks containing sterile medium plus concentrations of 0.5, 1.0 or 2.0~ (w/w) dry spices were inoculated with 2.5 ml of the thawed culture diluted with 0.1% peptone water such that the initial bacterial conc, ntration in the flasks was approx. 106 celis/ml. The flasks were incubated at 35°C. Samples for bacterial counts and titratable acidity were taken at 24-h intervals. For experiments with essential oils, 1-ml portions of oils in ethanol were added to duplicate flasks containing sterile medium to provide concentrations of 150, 300 or 600 ppm, corresponding approx, to the contents of essential oil when the dry spices were added. Ethanol (1 nil) was added to the controls. Bacterial counts were determined by conventional pour-plate techniques using APT agar (Difco). Titratable acidity was expressed as ml of 0.1N NaOH required to titrate to pH 7.0 (Zaika et al., 1983). The initial titratable acidities of the liquid medium were 0.16-0.2 ml.
Results and Discussion The effect of cumin, oregano and their essential oils on growth and acid production on Lactobaciilus plantarum is shown in Fig. 1. Addition of cumin did not affect growth, whereas acid production increased slightly. Cumin essential oil appeared to retard growth and decreased acid production at the highest concentra-
83
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81
FOOD 00399
Short c o m m u n i c a t i o n
Inhibitory and stimulatory effects of cumin, oregano and their essential oils on growth and acid production of Lactobacillus plantarum and Leuconostoc mesenteroides Merih Kavan~ ~, Attila Akgtil 2 and Ayten Dogan
3
I Biology Department, Facultyo/Sciences andArts, Anadolu University, Eskqehir, and : Food Science and TcchnoloD, Department, Facultyof Agriculture, Atat~k University, Erzurum, and 3 Food Science and T e c h ~ ~ Facultyo/Agriculture, Ankara Umvcesity, Dqkapt.Ankara, Turkey (Received 12 Match 1990; accepted 8 January 1991)
Cumin at concentrations of 0.5, 1.0 and 2.0 q~ (w/w) stimulated growth and acid production of /..~t~ p/m~aram and Lz,tg'o,w~oc m e a m t ~ in a liquid medium. Essential oil from cumin at Irish conceatratio~ (300 and 600 ppm) inhibited growth and acid production of Laaobaci//a~ p/aataram. Aftra" a ¢s~tain period, growth of ~ o ¢ mc.g,ntermdcs was observed at all concentrations (150, 300 and 600 ppm) and its acid production was stimulated at 600 ppm. Oregano and its esseatial oil at all concentrations inhibited growth of both cultures. Acid production by Lactobacillus plantarum was stimulated by oreilam~ spice. Key words: Spice; Essemial oil; Lactic acid bacteria; Inhibitory effect: Stimulatory effect
Introduction Most of the studies reported on the antimicrobial activity of spices and essential oils involved pathogenic or spoilage microorganisms, and a few reports on starter cultures e.g. lactic acid bacteria are available (SheleL 1983; Janssen et al., 1987). These reports suggest that lactic acid bacteria are relatively resistant to the toxic effects of spices or essential oils. Furthermore, some spices have been shown to exert a stimulatory effect on these organisms, which resulted in enhanced growth and/or acid production (Karaioannoglou et al., 1977; Shelef et al., 1980; Tiwari and Pandey, 1981). Effects of spices on starter cultures used in fermentation of meat products has been investigated. Lactobacillus plantarum was found to be stimulated by spices, and the effect appeared to be associated with the natural spices rather than with Correspondence (Present) m/dress: A. Akffll, Zirsutt Fak.. $el~k 0niv., 42049 Konya. Tlirkiye.
82 their oleoresins (Nes and Skjeivale, 1982). A mixture of some spices enhanced fermentation of Lebanon bologna sausages (Zaika et al., 1978: K.issinger and Zaika. 1978; Zaika and Kissinger, 1979). It has been reported that rmcroorganisms can develop resistance towards inhibiting effects by spices (Zaika and Kissinger. 1981: Zaika et al., !983). In the present study the influence of two Turkish spices, cumin fruits and oregano leaves, and their essential oils were tested on Lactobacillus plamarum and Leuconoswc mesemeroides, in a liquid medium. These spices are commonly used in various fermented food products.
Materials and Methods
Cultures of Lactobacillus planmrum NRRL B-4496 and Leuconostoc mesenteroides NRRL B-512F (from USDA, Agriculture Research Service, Peoria, IL) were used throughout the study. According to the supplier, these are single-strain cultures. Cumin (Cuminum cyrmnum L.) dried fruits and oregano (Origanum onites L) dried leaves and oils were commercially produced. The oil yields were 3.0 and 3.1~ (v/w) respectively. The fermentation medium was prepared by dissolving 3 g beef extract (Difco), 5 g tryptone (Difco), 20 g sucrose and 20 g glucose in 1 1 of distilled water. The pH of the medium was adjusted to 6.5 with 6N H2SO4. Aliquots of the medium were dispensed into Erlenmeyer flasks, and heat-sterilized. The appropriate levels of spices were added before the sterilization. Duplicate flasks containing sterile medium plus concentrations of 0.5, 1.0 or 2.0~ (w/w) dry spices were inoculated with 2.5 ml of the thawed culture diluted with 0.1% peptone water such that the initial bacterial conc, ntration in the flasks was approx. 106 celis/ml. The flasks were incubated at 35°C. Samples for bacterial counts and titratable acidity were taken at 24-h intervals. For experiments with essential oils, 1-ml portions of oils in ethanol were added to duplicate flasks containing sterile medium to provide concentrations of 150, 300 or 600 ppm, corresponding approx, to the contents of essential oil when the dry spices were added. Ethanol (1 nil) was added to the controls. Bacterial counts were determined by conventional pour-plate techniques using APT agar (Difco). Titratable acidity was expressed as ml of 0.1N NaOH required to titrate to pH 7.0 (Zaika et al., 1983). The initial titratable acidities of the liquid medium were 0.16-0.2 ml.
Results and Discussion The effect of cumin, oregano and their essential oils on growth and acid production on Lactobaciilus plantarum is shown in Fig. 1. Addition of cumin did not affect growth, whereas acid production increased slightly. Cumin essential oil appeared to retard growth and decreased acid production at the highest concentra-
83
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B 9
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