Preparation of fungal alcoholic starter using rice malt as substrate

Abstract

In this study, rice malt was used as the substrate to culture Saccharomyces cerevisiae for the preparation of defined fungal alcoholic starter. Defined mould starter using Amylomyces rouxii was prepared on the substrate of maize powder and rice husk. The different ratios of rice powder and rice malt were examined: A1 (rice malt only), A2 (1:0.5), A3 (1:1), A4 (1:2), and A5 (1:3). The results showed that the treatment of only rice malt gave the highest ethanol concentration (11.30% v/v) and the yeast population at 8.13 log CFU/g. The mould starter (8.74 log CFU/g) was added into the yeast starter at different ratios (0.5%, 1.0%, 1.5% and 2.0% w/w) for testing the fermentation capacity. Maximum ethanol concentration was 13.67% v/v when the defined fungal starter supplemented with 1% of mould starter and the incubation time for solid-state fermentation was 2 days, and 4 days for alcoholic fermentation stage. The yield of pilot-scale production (8 kg of rice) was found at 1.23 liters of rice white distilled spirit (ethanol concentration was 30% v/v) per one kilogram of rice. Aldehyde concentration of final distilled product was 33.8 mg/L and the quality score was obtained at 14.2/20 by sensory evaluation. This research was indicated the promising application of defined fungal alcoholic starter in local rice white distilled spirit manufactures.