Changes in Lactic Acid Bacteria and Quality of Gac Yoghurt Supplemented with Carbohydrate Sources during Chilled Storage

Abstract

Gac yoghurt is formulated by mixing gac juice with cow milk and probiotics to form a thick yellow fluid. The research objective was to study the effect of carbohydrate sources (inulin, honey, sucrose, fruit syrup, and sucrose) on lactic acid bacteria remaining after the chilled storage for 28 days. The gac yoghurt was analyzed with physicochemical and sensory characteristics. The experimental design was a Complete Randomized Design (CRD) with eight parameters (total soluble solids, pH, lactic acid content, syneresis, texture, colour, lactic acid bacteria count, and sensory evaluation). The results showed that gac yoghurt in the presence of honey had a higher lactic acid count than other yoghurt samples throughout 28 days of storage. The lactic acid growth was observed in the first two weeks, then it was almost constant in the third week and levelled off at the end of storage. The addition of carbohydrates resulted in a lower pH than that of the control. It increased total soluble solids, titratable acidity, and syneresis effect. Gac yoghurt with inulin enrichment kept for 28 days showed a firmer texture and lighter in colour than the rest. However, sensory results showed that gac yoghurt with sucrose was the most preferred formulae based on the average hedonic scores followed with the yoghurt fermented by honey, inulin, and fruit syrup, respectively.