PRODUCTION OF FUNCTIONAL FERMENTED MILK PRODUCTS

Abstract

In this study, the aim was to evaluate the viability of Lactobacillus casei 01 that was incorporated into ice cream using four different technological techniques: technique 1, ice cream mix was directly inoculated with freeze-dried L. casei 01 culture prior to aging and without fermentation; technique 2 or 3, skim milk (50% of total skim milk used in the preparation of ice cream mix) was fermented with L. casei 01 at 37 ○C until a pH of 4.5 or at 30○C until a pH of 5.5 was reached; the coagulated milk was cooled to 7○C, and then added to the remaining ice cream mix prior to aging; and technique 4, two aged ice cream mixes were mixed together prior to freezing, one of them was without sugar and fermented by L. casei 01 at 30°C until a pH of 5.5 and the other contained sugar and did not contain L. casei 01.The effect of fortification with Lactobacillus casei 01 on the physical properties and sensory characteristics of the produced ice cream was studied. The following results were obtained: • The freeze-dried Lactobacillus casei 01 culture that was added directly to ice cream mixes without fermentation (technique 1) had no significant effect on the physical properties or sensory characteristics of ice cream samples. • Although there was a significant decrease in the number of viable Lactobacillus casei cells throughout storage, but aging and freezing together had a greater impact on viability of L. casei cells in ice cream samples. • Fermentation with Lactobacillus casei 01 at 30°C and pH 5.5 can be used to manufacture high quality probiotic ice cream but through the fourth technique to maintain the largest number of L. casei in ice cream samples (>107cfu.g−1) and without probiotic flavor. • All 4 technical ice cream samples were acceptable and gave a good total impression with no marked off-flavor.