Rheological and Antioxidant Properties of Purple Yam Yoghurt Enhanced with Alginate-Chitosan Microcapsule Bacteria

Abstract

Yoghurt is a diary product that contain with probiotics such as Lactobacillus bulgaricus, Streptococcus thermophilus, and Bifidobacterium longum. The microencapsulation process in bacteria increased the nutritional value of yoghurt. Fortification of purple yam contains rich anthocyanins could increase the health benefit of yoghurt. The aimed of this study are to determine the rheological and antioxidant properties of purple yam yoghurt. Microencapsulation on B.longum used the extrusion method. Water holding capacity (WHC), syneresis, pH, viscosity, color, and antioxidant were measured to determine the quality of yoghurt. Based on the analysis, the addition of purple yam in yoghurt increased WHC and decreased syneresis. Antioxidants assay showed that anthocyanins in purple yam increased the antioxidant activity. Purple yam yoghurt with microencapsulated bacteria has best quality of yoghurt based on the WHC, syneresis, pH, and antioxidant properties. This result suggested that microencapsulated bacteria and fortification of purple yam could increase the health benefit of yoghurt.