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Effect of starter culture as a source of microbial contamination on the quality and safety of yogurt products in Egypt
Yogurt is one of the most common dairy foods in Egypt, yet the stability and shelf-life of yogurt remain a challenge to local producers. Thus, the objective of this study was to examine the effect of starter culture as a source of contamination on the quality and safety of yogurt product. In this study, we examined three groups of yogurt products. In group one, we collected 100 commercial yogurt products available in the marketplace. In group two, we made 10 yogurt batches ourselves using different yogurt starter cultures obtained from the local dairy industry. In group three, we made yogurt using yogurt culture from food microbiology stock culture. We then evaluated the types of microbial groups in relation to spoilage before and after storage of yogurt under chill condition and examined the microbial quality during storage at 7C for 14 days. Our results showed that during storage, there was an undesirable change in the commercial products as well as in yogurt products made with commercial starter cultures. All samples in groups one and two tested positive for Aspergillus spp. aflatoxin M1 and Salmonella spp. By contrast, the use of the control starter cultures prevented the presence of these contaminants in group three. Our results thus demonstrated that the use of a safe starter culture would be a promising approach to ensure the safety and quality of yogurt when it reaches the consumer.
Keywords: Starter culture, Yoghurt, Safety