Characteristics of probiotic glutinous rice tapai with the addition of Lactobacillus plantarum 1 RN2-53 and some natural dyes

Abstract

Tapai is a traditional Indonesian food usually made from cassava and glutinous rice. The study aims to determine natural dyes that produce the highest quality probiotic glutinous rice tapai. The study was conducted experimentally using a complete randomized design consisting of four treatments, and each treatment was repeated four times. The treatment in this study was the soaking of glutinous rice into natural dye extracts, namely red dragon fruit extract, purple sweet potato extract, and suji leaf extract, with different concentrations, namely 10%, 15%, 20%, and 25%. The data obtained were statistically analyzed using variance analysis and continued with Duncan's new multiple-range test (DNMRT) at a level of 5%.  The results showed that natural dye extracts with different concentrations have a noticeable influence on total lactic acid, alcohol content, total lactic acid bacteria, antioxidant activity, and sensory characteristics of color, aroma, taste, and hardness.  The soaking treatment in red dragon fruit extract and purple sweet potato extract with a concentration of 20% resulted in glutinous rice tapai, preferred by panelists. Furthermore, the characteristic pH value of 3.35-3.41, total lactic acid 0.61-0.70%, alcohol content 0.33-0.42%, total lactic acid bacteria 9.11-9.40 CFU/mL, and antioxidant activity 167.35-102.51 ppm.