Evaluating the behaviour of probiotic Bacillus coagulans XY1 in fruit juices and survival during heat treatment

Sammanfattning: It has become more important for people worldwide to eat and drink products that offer us health- promoting benefits, which traditional foods do not possess. These kinds of products are called functional foods and have been fortified using vitamins, minerals or probiotics among others. Today, there are a lot of probiotic strains on the market and the first part of the aim of this study was to evaluate the behaviour of a novel probiotic strain called Bacillus coagulans XY1 by incorporating it into two different fruit juices and follow its viability, stability and performance over a storage period of 10 weeks. In addition the physicochemical properties pH and lactic acid concentration was monitored in the samples throughout the storage period. The juices the probiotic strain was incorporated into were one orange and one pomegranate juice and they were both stored at 8-10°C in a refrigerator. The second part of the aim was to study the survival of Bacillus coagulans XY1 through different heat treatments. It was found that in both juices, the probiotic strain was able to survive throughout the storage time. However, the viability of the strain in the juices did not keep the required concentration of 107 cfu/mL at every testing occasion. The pH value in the juices stayed stable indicating that the strain was metabolically inactive during storage and a sensory evaluation including aroma, appearance and colour, showed that the quality of the juices was not affected by the probiotic when refrigerated. The heat treatment did affect the viability of the strain greatly. The results showed that there was a great decrease in viability of the strain after the different heat treatments were performed. This needs to be further investigated in the future to find a suitable treatment for probiotic fruit juices and it needs to be performed more similar to industrial standards for more reliable results. In conclusion, fruit juices seemed to be an appropriate food matrix for inoculation of Bacillus coagulans XY1 to develop future probiotic beverages with a long shelf-life period.