Evaluating the effect of Lactobacillus helveticus on survival of Penicillium notatum and Candida albicans in probiotic set yogurt

Abstract

Abstract Background: The dairy industry is one of the most important food industries in the country, which is directly related to people's health, but today dairy products, especially yogurt, have been challenged by fungal contamination. This increases the demand for dairy products and, on the other hand, threatens the health of consumers. On the other hand, due to consumers' concerns about food safety and the growing demand of consumers for foods that have undergone minimal processing, the tendency to develop and use lactic acid primers has increased day by day. For this purpose, the effect of Lactobacillus helveticus on the survival of Penicillium notatum, which is an indicator mold in fungal rot and Candida albicans yeast, which is a problem in fermented dairy products, has been considered. Materials and methods: For this purpose, 12 types of yogurt were produced: The incubation conditions (after inoculation of starter and probiotic species) were the same for normal and probiotic yogurt and incubation was continued until pH = 4.7. The inoculation rate of Lactobacillus helveticus was 109 cfu / g and the inoculation rate of fungal species to infected yogurts was 105 cfu / g. The produced samples were stored for 28 days at 4 ° C and were evaluated for microbial, physicochemical and sensory properties in three replications during days (1,7, 14, 21, 28). Results: The results showed that the starter and acidic environment of yogurt could not affect the number of Candida albicans and Penicillium notatum and Lactobacillus helveticus independently reduced the number of Candida albicans and Penicillium notatum. Probiotic yogurt produced was acceptable in terms of physicochemical and sensory properties (p > 0.05) but Lactobacillus helveticus independently reduced the number of Candida albicans and Penicillium notatum. Lactobacillus helveticus was able to reduce the mold of Penicillium notatum from 4×105 to 3×103 and the yeast Candida albicans from 3×105 to 5×104 in probiotic yogurt (p < 0.05). The number of Lactobacillus helveticus after 28 days of storage with 3.3×109 was in the appropriate range to present a probiotic product. The results of sensory evaluation of probiotic yogurt and regular yogurt did not show a significant difference in overall acceptance (p > 0.05), Although ordinary yogurt gained more points. Conclusion: According to the results of the present study, Lactobacillus helveticus can be used as an antifungal and probiotic agent in yogurt. Keywords: Probiotic yogurt, Lactobacillus helveticus, Inhibition, Fungal spoilage