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Anthocyanins are naturally active substances. In this study, anthocyanins from black rice were obtained by membrane filtration and column chromatography separation. Five anthocyanin monomers in black rice extract were identified by HPLC-MS/MS, and the major anthocyanin monomer (cyanidin-3-glucoside, C3G) was purified by preparative HPLC (Pre-HPLC). The proliferative effects of the anthocyanins on Bifidobacteria and Lactobacillus were investigated by determining the media pH, bacterial populations and metabolic products. After anaerobic incubation at 37 °C for 48 h, not only the pH of the media containing C3G was lower than that of the extract of black rice anthocyanin (BRAE), but the numbers of both Bifidobacteria and Lactobacillus were also significantly increased. Furthermore, hydroxyphenylpropionic, hydroxyphenylacetic, and hydroxybenzoic acids and other metabolites were detected by GC-MS in vitro. Our results revealed that the anthocyanins and anthocyanin monomers from black rice had prebiotic activity and they were metabolized into several small molecules by Bifidobacteria and Lactobacillus. [ABSTRACT FROM AUTHOR]

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]

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]

• Pre-germination was used to improve the nutritional value of brown glutinous rice. • Antagonism between ultrasound treatment and CaCl 2 stress was explored in soaking. • Both CaCl 2 and ultrasonic treatments improved GABA production during germination. • Energy metabolism, lipid metabolism and protein hydrolysis were enhanced. • Low-frequency ultrasound with salt stress would short the germinated time. In order to fortify γ-aminobutyric acid (GABA) of brown glutinous rice (BGR), pre-germination strategy was employed, and effects of low-frequency (28 kHz) ultrasound treatment combined with CaCl 2 stress on the sprout length, germination rate, morphology, color, water, total polyphenol content (TPC), starch, protein, GABA contents and relevant metabolites were investigated. The germination rate would be inhibited under CaCl 2 concentration ≥ 2.0 % during 24 h soaking without ultrasound treatment, and no significant difference was also observed combined with 9 h ultrasound treatment. Ultrasound treatment was beneficial to water absorption, TPC enrichment, energy metabolism, lipid metabolism and protein hydrolysis. Higher contents of GABA (3.29 folds), pyruvic acid (7.63 folds), glycerol (4.88 folds), glutamate (2.02 folds) and glucose (1.32 folds) were obtained due to the antagonistic effect between the 30 w ultrasound treatment and 2.0 % CaCl 2 stress at the 9 h pre-germination, and energy, lipid and protein metabolomic pathways were all involved in the GABA accumulation. [ABSTRACT FROM AUTHOR]

A simple and efficient method to extract and purify anthocyanins from black rice was developed in this work. After pretreatment of black rice, anthocyanins were extracted by buffer solutions, and were purified using membrane separation and resin adsorption. The single-factor experiments and orthogonal design were applied. The results showed that extraction ratio could be 0.99 ± 0.01% under the optimal condition of liquid-solid ratio 12:1, temperature 50C, time 80 min and pH 3.2. The 3 kDa molecular weight cut-off (MWCO) was used to remove proteins and polysaccharides, and the DM301 resin was found to have both good adsorptivity and desorptivity for anthocyanins. After the elution using 85% (vol/vol) ethanol solution, the purified anthocyanins were obtained by retention with the membrane of 200 Da MWCO. The recovery and purity of the anthocyanins finally obtained was 0.86% and 95.93%, respectively. The results are beneficial to the large-scale extraction of anthocyanins from black rice. Practical Applications Due to the growing demand for natural pigments, the natural anthocyanins have drawn great attentions. However, the immaturity of the large-scale purification procedures has limited the application of anthocyanins in functional food and pharmaceutical industries. Since the black rice is the rich source of anthocyanins, the large-scale water extraction and macroporous absorbent resins purification parameters were systematically investigated in the current study. About 0.86 g anthocyanins could be obtained from per 100 g black rice based on the large-scale method, which has a good recovery, and the purity could reach 95.93%. Meanwhile, the whole procedure was green and non-pollution as the primary solvents were water and ethanol. Furthermore, the results also would be conducive to the processing and utilization of black rice. [ABSTRACT FROM AUTHOR]