Effects of Shallots (Allium stipitatum) aqueous and ethanolic extracts on the Streptococcus thermophiles and Lactobacillus bulgaricus in TSB medium
Subject Areas : Industrial Food Microbiology
Sara
Ashrafian
1
(Department of Health and Food Quality Control, Faculty of Veterinary Medicine, shahrekord Univercity, Shahrekord, Iran.)
Mojtaba
Bonyadian
2
(Department of Healyh and Food Quality Control, Shahrekord University)
Hamdallah
Moshtaghi
3
(Department of food quality control)
Keywords: starter, Extract, Yogurt, Shallot,
Abstract :
Yogurt is one of the most popular dairy products is widely consumed around the world, due to its high nutritional value and the presence of beneficial bacteria. This study aimed to investigate the effect of ethanolic and aqueous extracts of shallot on the survival of yogurt starter (Streptococcus thermophilus and Lactobacillus bulgaricus). Aqueous and ethanolic extracts of shallots were extracted by the soaking method. The MIC and MBC of the extracts were obtained for starter bacteria by the microdilution method. Extracts were added to milk at concentrations obtained in the MIC along with a 3 percent yogurt starter. The inoculated milk was incubated at 45 ° C until pH = 4.5. The yogurts were cooled and stored at 4 °C. On days 1, 3, 7, and 14, pH, acidity, and LAB count tests were performed on yogurt. The results showed that on days 1, 3, 7, and 14, the acidity and pH of the extracts groups were significantly different from the control group (p <0.05). Also, the LAB count on days 1, 3, 7, and 14, in the extract groups was significantly different from the control group (p <0.05). The results also showed that the inhibitory effect of aqueous extract on starter bacteria was more than ethanolic extract of shallot (p <0.05). In conclusion, the results revealed that the starter bacteria in yogurt in presence of Shallot extracts were alive and active until day 14 during refrigeration, which can transmit the probiotic effects of yogurt and shallots to the consumer.
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