The Effect of Cumin Essential Oil Stress on Survival and Stability of Lactobacillus casei in Probiotic Yogurt

One of the main challenges in using probiotics is keeping them alive and active during the food production and storage process. Therefore, the aim of this study was to investigate the effect of stress less than the minimum inhibitory concentration on the survival of Lactobacillus casei and some physicochemical properties of probiotic yogurt during refrigeration. Cumin essential oil was extracted by steam distillation and its composition was determined by gas chromatography-mass spectrometry GC/ MS. Then, the effect of 50% MIC cumin essential oil stress were examined by comparing the stress treatment with the control in terms of the L. casei population, pH, acidity, and syneresis percentage in probiotic yogurt during storage in the refrigerator for 28 days. Data were analyzed by Tukey in SPSS software version 18. According to the results related to the constituents of the essential oil, the most compound was propanal-2-methyl-3-phenyl with 24.2%. Also, the results related to yogurt showed that the number of Lactobacillus casei bacteria and pH in both treatments decreased during the storage period so that the intensity of pH reduction in stress treatments was higher than the control treatment (P <0.05). But bacterial changes of Lactobacillus casei in the two treatments were not significantly different (P> 0.05). The percentage of syneresis and acidity increased during the maintenance period for all treatments and the intensity of increase in stress treatment was higher than the control (P <0.05). All in all applying stresses below the MIC resulted in the survival of L. casei in the recommended amount (106 -107 CFU ml-1) in the probiotic yogurt until the end of 28 days.