Influence of prebiotic components on probiotics stability during in vitro digestion of whipped frozen dessert based on curd whey

The aim of the study is to investigate the effect of apple pomace and pectin oligosaccharides on the survival of probiotic microorganisms during in vitro digestion of whipped frozen dessert based on curd whey. In accordance with the objectives of the study, four types of mixtures for frozen dessert were prepared: control, with 5 % apple pomace, with 5 % hydrolyzed apple pomace and with 5 % filtrate of hydrolyzed apple pomace. For fermentation, activated probiotic cultures of Propionibacterium freudenreichii subsp. shermanii (OOO Propioniks, Russia), L. acidophillus (Experimental Biofactory VNIIMS, Uglich, Russia) and L. reuturi (OOO Bakzdrav, Russia) were used. The in vitro digestion of the samples was carried out in accordance with the method simulating the stages of digestion in the gastrointestinal tract: oral cavity, stomach and small intestine. The experiment was carried out in triplicate. The safety of probiotic cultures was assessed as the ratio of viable bacterial cells that remained at each stage of in vitro digestion to the number of bacterial cells in the finished product. The results of bacterial counting after the first stage of digestion in the oral cavity showed no significant loss of microorganism viability in all samples. At the intestinal stage, a population reduction relative to the control (finished product) was observed for propionic acid bacteria by 38 %, acidophilus bacillus by 31 %, and lactobacillus reuteri by 49.6 %. The presence of dry and hydrolyzed apple pomace in the samples increased the survival rate of the cultures. In the samples with L. acidophillus, the survival rate compared to the control was higher with hydrolyzed apple pomace by 9.7 %, with dry apple pomace by 7.2 %, and with pectin oligosaccharides by 6.5 %. L. reuteri showed better survival when using hydrolyzed apple pomace – 11.1 % higher than in the control. When using pectin oligosaccharides and dry apple pomace, this indicator was higher than the control by 8.8 and 5.1 %, respectively. In the case of propionic acid bacteria, the percentage of surviving starter microflora was 68.2 % in samples with hydrolyzed apple pomace, 65.1 % with pectin oligosaccharides and 64.7 % with dry apple pomace. The use of apple pomace in dry and hydrolyzed form, as well as pectic oligosaccharides from apple pomace in a probiotic whipped frozen dessert based on curd whey, contributed to an increase in the resistance of probiotics L. acidophillus, L. reuteri and Propionibacterium freudenreichii subsp. shermanii to in vitro digestion processes.