Fermentation profiling of rice wine produced by Aspergillus oryzae KSS2 and Rhizopus oryzae KJJ39 newly isolated from Korean fermentation starter

Minjoo Kim,Jeong-Ah Seo

doi:10.1186/s13765-020-00582-2

Minjoo Kim, Jeong-Ah Seo

Open Access

https://doi.org/10.1186/s13765-020-00582-2

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Abstract

The objective of this study was to determine the fermentation characteristics of rice wine produced by koji inoculated with Aspergillus oryzae KSS2 and Rhizopus oryzae KJJ39 on moisturized wheat-bran and rice grain. We also compared rice wine samples produced in this study and three commercial Makgeolli. The alcohol content was about 12% higher in the rice wine samples fermented by wheat-bran koji than in the other samples. In all of the samples, the range of pH value was 3.8–4.6 and the total acid was below 0.5. The soluble solid content was highest in the rice wine sample prepared by the wheat-bran R. oryzae KJJ39 koji (15.5°Brix) and overall relatively higher in the samples with wheat-bran koji than rice koji. The content of reducing sugar was twofold higher in rice wine prepared by koji inoculated with R. oryzae KJJ39 than A. oryzae KSS2. The volatile acid content was higher in rice wine produced by the wheat-bran A. oryzae KSS2 koji than the others. In the analyses of five organic acids, A. oryzae KSS2 was found to produce more malic acid and fumaric acid while R. oryzae KJJ39 to do more citric acid, lactic acid and acetic acid. The rice wine sample prepared with the wheat-bran A. oryzae KSS2 koji contained much higher concentration of sucrose, maltose and amino acids. Comprehensively, the results of fermentation profiling suggest that both A. oryzae KSS2 and R. oryzae KJJ39 can be applied to the production of rice wine as a valuable fungal isolate for fermentation start.

Highlights

Makgeolli is a traditional Korean rice wine that has been consumed by Koreans for centuries
The quality of Makgeolli is usually determined by the alcohol contents, total acid contents, organic acid concentrations and flavor profile, and these factors vary depending on the production and storage conditions [8, 9]
To determine and compare the fermentation characteristics, we investigated the physiochemical properties of the rice wine samples produced by both wheat-bran koji and rice koji inoculated with Aspergillus oryzae KSS2 and Rhizopus oryzae KJJ39 which have been selected as high amylolytic enzyme producers in our previous study [11] and the commercial Makgeolli samples

Summary

Introduction

Makgeolli is a traditional Korean rice wine that has been consumed by Koreans for centuries. The taste of Makgeolli is determined by a combination of four flavor profiles: sweet, sour, bitter, and astringent. Makgeolli contains essential amino acids such as lysine, leucine, and arginine, as well as esters such as ethyl acetate, amyl acetate, and ethyl caproate, which are responsible for the sour taste of the rice wine [1,2,3,4,5]. Besides the nutritional and functional benefits of drinking Makgeolli, the presence of raw yeast gives it a unique taste when compared to other alcoholic beverages [4, 6, 7]. The quality of Makgeolli is usually determined by the alcohol contents, total acid contents, organic acid concentrations and flavor profile, and these factors vary depending on the production and storage conditions [8, 9]

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