Physicochemical, microbiological evaluation of probiotic milk beverages fortified with concentrated apple juice

Abstract

The preparation of dairy beverages rich in probiotic microorganism and fortified with concentrated apple juice (CAJ) is the goal of this study. Culture (ABT-5) contained Streptococcus thermophilus, Lactobacillus acidophilus, and Bifidobacterium bifidium were used to prepare the dairy beverages. Sweetened cow milk which inoculated with cultures (0.1g/L of milk) was used as a control beverage sample (C). Samples were fortified with 8, 10 and 12% (w/w) CAJ to create treatments T1, T2, and T3, respectively. The chemical, microbial and sensory evaluation of samples were acheived fresh and during storage at 5±2oC. The results revealed that the pH values decreased, but the total solids, ash, water-soluble nitrogen (WSN), and total volatile fatty acid (TVFA) contents increased as the level of CAJ increased. During the storage period ; the pH value also decreased, while WSN and TVFA in all dairy beverages increased. Fat contents showed slight increases between control and fortified samples, however, slight decrease was noticed in their values during storage period. The counts of St. thermophilus and Bifidbacterium bifidium in fortified samples were decreased as CAJ ratio increased and as storage period progressed, while the counts of L. acidophilus were increased as the ratio of CAJ increased; else, they decreased as storage period increased. Organoleptic properties of samples fortified with CAJ during 14 days of storage recorded obvious variations in all evaluated properties. The total acceptability indicated that T2 samples (10% CAJ) had the highest degrees and possessed favorite properties with probiotic and healthy behavior.