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Summary: This study investigated the effect of Lactobacillus plantarum F25‐4 assisted rice soaking (LAS) on the cooking properties of japonica rice used for Chinese rice wine (CRW) production. The effects of LAS and natural soaking were compared based on the chemical composition, thermal characteristics, infrared spectroscopy and sodium dodecyl sulphate‐polyacrylamide gel electrophoresis of rice flour. After LAS, the protein content of the rice was reduced by 17.63%, and the initial temperature (To), peak temperature (Tp) and conclusion temperature (Tc) were reduced by 36.86%, 17.89% and 1.61%, respectively, as revealed by differential scanning calorimetry analysis. The Zeta (ζ) potential value changed from −8.75 mV to −3.99 mV, and the minimum cooking time was reduced by 40% to only 15 min. The viscoelasticity of LAS rice increased after gelatinisation, as confirmed by confocal laser scanning microscope images. The glutelin precursor of the LAS rice disappeared, and the disorder of protein secondary structure increased, but there was no significant difference in the starch crystal area. LAS effectively improved the cooking properties of rice by changing the protein configuration on the surface of starch granules and reducing protein adsorption, leading to increased starch water absorption and decreased rice gelatinisation temperature. Our research suggests that LAS can reduce the cooking temperature of rice in CRW production, thus saving steam consumption during cooking. [ABSTRACT FROM AUTHOR]

BACKGROUND: Black rice contains a variety of bioactive substances that contribute to the high nutritional value of black rice wine (BRW). However, the dense bran layer of black rice retards the fermentation rate and reduces the dissolution of active components. Hence, this study aims to investigate the effects of pre‐gelatinization (PG) before cooking and cellulase (CE) addition during fermentation on the fermentation performance of BRW and its antioxidant activity. RESULTS: PG combined with CE treatments (PGCE) increases the alcohol content, free amino acid content, volatile flavor content and total antioxidant activity of BRW by 90.81%, 15.36%, 38.05% and 19.56%, respectively, compared with the control group. Scanning electron microscopy, low‐field nuclear magnetic resonance and texture properties analysis indicate that PG treatment increases gelatinization degree of starch during cooking, decreases bound water content in cooked black rice and promotes unbound water release. CE destroys the aleurone layer structure, facilitates the release of unbound water and the exposure of rice starch, thus increasing the reaction area and extravasation content significantly, which is beneficial to microbial growth and fermentation. Incomplete aleurone layer also promotes the dissolution of anthocyanins, phenols and other active substances, increasing the antioxidant activities of BRW. CONCLUSION: PG and CE treatments reduce the fermentation time and improve the quality of BRW by destroying the black rice structure. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of Lactiplantibacillus plantarum F25-4 assisted rice soaking water on the fermentation performance of Chinese rice wine (CRW). Compared to CRW using natural rice soaking water (NSR), CRW using rice soaking water assisted by L. plantarum F25-4 (LSR) exhibits an 80.69% increase in amino nitrogen content, a 26.03% increase in total acid content, a 79.54% increase in free amino acid content, and a 22.37% increase in volatile flavor content. The filtration efficiency of mash with rice soaking water by L. plantarum F25-4 was higher than that of NSR. Fourier transform infrared spectroscopy (FTIR), particle size analysis, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed an increased average particle size of the rice soaking water assisted by L. plantarum F25-4, coupled with a reduction in the high molecular weight of soluble protein. This enhancement facilitated the utilization of rice protein by microorganisms and the transformation of flavor substances, contributing to flavor formation. L. plantarum F25-4 assisted in soaking and the reuse of rice soaking water to improve the quality of CRW by optimizing the utilization of rice protein. Therefore, this method lays the theoretical foundation for the sustainable reuse of rice soaking water. [Display omitted] • Lactiplantibacillus plantarum F25-4 facilitated the utilization of rice protein. • Rice soaking water assisted by L. plantarum F25-4 was reused for rice wine brewing. • Recycling rice soaking water improved the quality of rice wine. [ABSTRACT FROM AUTHOR]

A higher fermentation capability and quality of a rice wine was achieved, using mixed fungal (Rhizopus chinonsis R01, Asperigillus niger A20, Mucor pusillus M05 and Saccharomyces cerevisiae S10) starter fermentation of japonica rice supplemented with α-amylase (AM), glucoamylase (GAM) and acid protease (AP). Results showed that alcohol content, free amino acids (FAA) and volatile flavor substances concentrations were increased by 49.22%, 85.54%, and 25.71% compared with the control group respectively. To understand the role of enzymes during rice wine brewing, the effects of hydrolases on chemical and physical properties of cooking rice, on the yeast growth, enzyme productivity of molds were determined. Rice starch was hydrolyzed effectively by AM and GAM, the viscosity reduced significantly, the enzyme contact area expanded, which accelerated the further hydrolysis of japonica rice. Increase of hydrolysate promoted the fungi growth, while improved the ability of molds to produce enzymes. AP promoted the protease activity of M. pusillus M05 and A. niger A20, improved protein utilization, increased the content of FAA and formed higher level of flavor substances in rice wine. The results indicate that hydrolase addition can change the physic-chemical state of the mash to enhance microbial biotransformation and modify flavor metabolism. • Enzymes could increase the ethanol content of rice wine prepared by known starters. • Enzymes could increase the content of FAA and flavor components in rice wine. • Enzymes increased the system fluidity and the reaction area of cooking rice. • Added enzymes could promote the growth and enzymes productivity of fungi. [ABSTRACT FROM AUTHOR]

In the present study, rice wine was produced by mixed moulds starters fermentation. The influence of mixed moulds starters on enological parameters, free amino acids (FAAs), flavor compounds, and sensory characteristics of rice wine were respectively investigated. Results indicated that the contents of ethanol, amino acid nitrogen, umami and sweet FAAs in rice wine obtained from rice fermentation using starter of simultaneous inoculation of R. chinonsis R01, A. niger A20, M. pusillus M05 and S. cerevisiae S10 (RAM-S) were higher than that of Control one using wheat Qu. In addition, flavor compound data revealed that the aroma of rice wine using different starters mainly differed in the amounts of alcohols and esters. FAAs, flavor compounds, sensory evaluation and partial least squares regression (PLSR) analysis demonstrated RAM-S wine had the best sensory characteristics with higher contents of esters, nitrogen-containing, umami and sweet FAAs, and lower of bitter FAAs. These findings demonstrated that the starter RAM-S is promising to produce rice wine with high quality standards both in flavor and fermentation performance. • The rice wine prepared by RAM-S starter could increase the ethanol. • The effect of mixed moulds starter on flavor compounds of rice wine was evaluated. • Umami and sweet FAAs in rice wine by mixed moulds fermentation was increased. • The composition of starter contributed to the flavor compounds of rice wine. [ABSTRACT FROM AUTHOR]