Chemical characteristics and viability of starter cultures of freeze-dried sweet potato extract-supplemented synbiotic yogurt

Abstract

The research aimed to determine the sucrose concentration as a cryoprotectant to obtain the chemical properties and the viability of Lactic Acid Bacteria (LAB) and Lactobasillus plantarum in the synbiotic yogurt. It adopted a one-factor Completely Randomized Design (CRD) by including sucrose in concentrations from 0 %, 2.5 %, 5 % to 7.5 %, three replications. The results showed various sucrose concentrations significantly affected the yields of the purple sweet potato extract- supplemented synbiotic yogurt, reduction-sugar level, the total of LAB, and the total of L. plantarum before and after the freeze-drying process, no significant impact on the moisture content and total quantity of LAB. The best treatment of the synbiotic yogurt was induced through the addition of sucrose with a concentration of 5 % as a cryoprotectant. The treatment signified the following characteristics: 14.797 % of yields, 7.51 % of water content, 14.59 % of reduction-sugar level, 1.98 × 109 CFU mL-1 of total LAB before the freeze-drying and 9.28 × 108 CFU mL-1 after the freeze-drying, 8.23 × 108 CFU mL-1 of total L. plantarum before the freeze-drying and 6.81 × 108 CFU mL-1 after the freeze-drying.