SYNBIOTIC YOGURT BASED ON LOCAL Lactobacillus plantarum AND HYDROLYSATE OF Kappaphycus alvarezii: EFFECT OF DIFFERENT STARTERS AND FERMENTATION TIME

Abstract

Synbiotic yogurt is a fermented milk product that is enriched with probiotics and prebiotics. This combination enhances probiotic viability, promotes bioactive metabolite production, and improves gut health by generating short-chain fatty acids (SCFA). Selecting an appropriate starter culture and fermentation time is essential for obtaining yogurt with desirable functional and physicochemical characteristics. This study aimed to determine the optimal L. plantarum starter treatment and fermentation duration of synbiotic yogurt with K. alvarezii hydrolysate as a prebiotic based on total lactic acid bacteria, pH, total titratable acidity, and reducing sugar con-tent. The factors included fermentation time (0, 12, and 24 h) and starter type (L. plantarum SK(5), NS(5), or their combination). The parameters analyzed were lactic acid bacteria (LAB) counts, total titratable acidity (TTA), pH, and reducing sugar. The proximate composition of K. alvarezii was as follows: 21.18% moisture, 28.91% ash, <0.02% fat, 3.81% protein, 46.11% carbohydrates, and 49.11% Hydrolysis produced 0.20 g/100 mL of reducing sugar with 42.98% recovery. The results revealed that starter type, fermentation time, and their interaction significantly influenced LAB counts, TTA, pH, and reducing sugar (p<0.05). The best treatment was yogurt produced with L. plantarum SK(5) for 24 h, yielding 9.27 log10 CFU/mL LAB, 0.74% TTA, pH 4.33, and 0.25% reducing sugar. Synbiotic yogurt formulated with L. plantarum SK(5) and K. alvarezii hydrolysate showed strong potential as an innovative functional food with greater health benefits than conventional yogurt.