Arup Nag

PhD Student

Thesis title: Understanding the factors responsible for loss in probiotic viability during high temperature storage

Probiotic bacteria are known for conferring beneficial effects to human health. However, the successful delivery of these bacteria to the human intestine via proper food matrices is challenging. Probiotic-containing food products are one of the major contributors to the growing functional food markets around the world. Probiotics are traditionally found in fermented dairy products such as fermented milk, yoghurts and cheese. However, it is now also common for them to be stabilized and fortified into powdered foods or nutraceutical formulations. At the end of their shelf life (typically 6 months to 1 year for dried products), the products need to contain cell viability of at least 106 colony forming units (CFU) per g to confer the desired health benefits. Unfortunately, maintaining the viability of probiotics in non-refrigerated foods over long shelf life is difficult. To date, non-refrigerated foods have generally failed to meet the required viability target at the end of shelf-life and probiotic foods outside the chilled dairy area remain scarce. Hence, there is strong industry demand for technologies that can improve probiotic survival in foods outside the traditional chilled, fermented dairy sector.

This PhD project has the primary objective of developing a novel encapsulation technology for probiotic bacteria, through which a range of probiotic bacterial strains could potentially be delivered in shelf stable dry and intermediate moisture foods. This project also aims to understand the underlying mechanism of the processes responsible for gradual decay in cell viability of one particular probiotic strain (Lactobacillus reuteri LR6) during long term storage at increased storage temperature. It is believed that proper understanding of the responsible factors would help further development of the technology to achieve the stated goal.