Evaluation of viability and chemical properties of fermented black rice-milk alternatives

Food Technology Department, Faculty of Engineering, Bina Nusantara University, Jakarta, Indonesia

^* Corresponding author: andreas.romulo@binus.ac.id

Abstract

This study investigates the development of fermented black rice-based milk alternatives, focusing on microbial viability, chemical properties, and nutritional potential. Seven formulations with varying concentrations of black rice extract (10%–100%) and full cream milk were fermented using Lactobacillus bulgaricus and Streptococcus thermophilus. LAB viability was highest in full cream milk (P1), decreasing from 10.5 log CFU/mL on day 0 to 9.4 log CFU/mL on day 30. In contrast, 100% black rice extract (P2) showed the lowest viability, declining from 9.47 log CFU/mL to 8.7 log CFU/mL. The pH of all formulations decreased over 30 days, with the most stable pH observed in P3 (10% black rice extract) at 4.23 ± 0.02 and the lowest in P7 (50% black rice extract) at 3.76 ± 0.01. Titratable acidity increased during storage, with P1 showing the highest rise from 0.30 ± 0.02% to 0.42 ± 0.02%, while P2 exhibited the smallest change, increasing from 0.17 ± 0.02% to 0.29 ± 0.05%. These findings highlight the influence of black rice extract concentration on the viability of LAB and the chemical properties of fermented milk alternatives. Future research should explore sensory evaluations, consumer acceptance, and the scalability of black rice-based milk fermentation for commercial production. Additionally, examining the impact of alternative fermentation techniques on nutritional and bioactive properties would provide further insights.