Viability of Probiotic Bacteria during Refrigerated Storage of Commercial Probiotic Fermented Dairy Products Marketed In Jordan

摘要

Objectives: The study aimed to measure the viability of probiotic bacteria in different probiotic fermented dairy products marketed in Jordan during their shelf lives. Methods: Ten products which were all known commercial probiotic fermented dairy drinks were purchased from main market stores at 0 day of processing, and kept under 4oC for the assigned time intervals (1, 7, 14 day). These products included 7 stirred yogurt Activia, Activia low-fat, Actimel, Baladna, Acti-Yogho, Moffedo, and Vital, and 2 set yogurt (Activia - apricot and peach, Activia light – strawberry) and one stirred yogurt (Activia- stirred). Samples were tested for probiotic count at those intervals in an unopened refrigerated bottles. Sensory evaluation using hedonic scale was carried out on the above products in an unopened package at the same indicated intervals. Morphology of probiotic bacteria in commercial products was also confirmed microscopically.Results: The results of the viability of probiotic counts in log10 remaining above 7 log until the end of shelf life (14 d) except for four products including Moffedo, vital, Activia set yogurt light – strawberry, and Activia (stirred yogurt) which decreased to 3.4, 4.9, 5.0, and 5.0 respectively at the end storage period. The pH for all products until the end of the study were between 4.1- 4.5. The best average of all sensory characteristics using hedonic scale (8.3) was for Actimel, whereas the lowest (7.1) was for both Moffedo and Activia set yogurt- Apricot and peach.Conclusion: The counts of probiotic bacteria in fermented dairy products is not always above the therapeutic dose of 6.0 log cfu/g, which urge governmental authorities to establish a standard related to these products.