Dairy Products Fortified with Probiotics

Project entitled:

Validation Conditions of Viability for Probiotics in Dairy Products

Denis Roy, Daniel St-Gelais, Gisèle Lapointe


Developing products to maintain the viability and activity of probiotic bacteria is a genuine technological challenge for manufacturers who wish to market functional foods. Cheese has advantages such as higher pH, a denser matrix and a higher fat content that can increase the likelihood that probiotic bacteria will survive the production and ripening process as well as transit through a human stomach. The main goal of this project is to determine the conditions in which the functional properties of probiotics in cheese can be made and kept viable. A model curd reproducing an environment similar to that found in Cheddar cheese was used to assess the combined effects of pH, salt/moisture percentage and ripening temperature on the survival and growth of various commercial probiotics during the aging of Cheddar. The viability of the Bifidobacterium animalis ssp. lactis BB-12 and Lactobacillus rhamnosus GR–1 strains on their own as well as in co-culture was determined in the context of a Cheddar manufacturing process and during the 12-week ripening of the cheese at 4°C and 8°C. The viability of probiotic bacteria in cheese was also assessed using two quantification methods: the classic method of counting on a light box and the molecular method known as qPCR/PMA. The results provided a better understanding of the factors that affect the viability and activity of probiotic bacteria in cheese as well as the development of molecular tools dairy processors can use to determine the viability of probiotic strains and ferments and to perform strain typing.