Influence of different baking temperatures of red kojic rice on the physicochemical properties, antioxidant capacity, and functional components of red starter wine.

BACKGROUND: To improve the quality of red starter wine, this study explored the effects of baking red kojic rice at varying temperatures on the physicochemical characteristics of red starter wine. Baking was predicated on understanding crucial enzyme activities and starch granule structure of red kojic rice at 75, 95, and 105 °C, leading to the production of three red starter wine variants (BHQW1, BHQW2, and BHQW3). RESULTS: The results revealed an increased alcohol (increase 0.50%), total sugar (increase 0.14 g L-1 ), and total acid (increase 0.54 g L-1 ) content in red starter wine fermented using baked red kojic rice compared with the control group (wine fermented with unbaked rice, HQW). Furthermore, both the 105 °C baked red kojic rice and its resulting BHQW3 demonstrated significantly higher red color values than HQW (increase 2.03 U g-1 and 0.15 U mL-1 respectively). The highest lovastatin content was presented in red kojic rice baked at 105 °C and its corresponding fermented wine (1420.63 ± 507.9 µg g-1 and 3368.87 ± 228.16 µg L-1 respectively). Additionally, BHQW groups displayed higher total flavonoids and phenols content than HQW. Regarding antioxidant capacity, all BHQW groups showed stronger overall antioxidant capacity than HQW. The determination of volatile components revealed the highest content of volatile compounds in BHQW2 (2621.19 ± 548.24 µg L-1 ) and significantly higher volatile esters in BHQW1 (254.46 ± 16.63 µg L-1 ). Moreover, 16 volatile compounds were identified only in BHQW groups, including isoamyl caprylate, 2-ethylhexyl alcohol, and benzaldehyde. CONCLUSION: Our findings suggested that the baking technique of red kojic rice could enhance the quality of red starter wine through enhancing antioxidant properties, increasing functional components, and enriching volatile flavor compounds, thus providing a foundation for new techniques in red starter wine production. © 2023 Society of Chemical Industry.

Safety evaluation and comparative genomics analysis of the industrial strain Aspergillus flavus SU-16 used for huangjiu brewing.

Huangjiu is a popular Chinese traditional alcoholic beverage, while its brewing processes have rarely been explored. We herein report the first gapless, near-finished genome assembly of the industrial strain Aspergillus flavus SU-16 for huangjiu brewing. This work provides insights and supports for the further industrial applications of A. flavus isolates by comprehensively studying of the safety and genomic variations of SU-16. We demonstrated that SU-16 is a non-aflatoxigenic A. flavus at both molecular and metabolic levels. Using of nanopore sequencing technology resulted in a complete genome sequence for all 8 A. flavus chromosomes, as well as the mitochondrion. Genome comparisons of SU-16 with reference strains identified the chromosomal rearrangements, revealed the adaption mechanism of SU-16 to huangjiu ecological niche, and found that SU-16 is a good repository for CAZymes and some bioactive secondary metabolites. The results will help to develop more scientific huangjiu fermentation processes, and explore metabolism pathways of desired or harmful components in huangjiu to improve its quality.

Combined use of single molecule real-time DNA sequencing technology and culture-dependent methods to analyze the functional microorganisms in inoculated raw wheat Qu.

Inoculated raw wheat Qu (IRWQ), which can be produced with high efficiency and low cost while maintaining stable quality, is a new Qu that has been applied to Huangjiu brewing. In this study, single molecule real-time DNA sequencing technology and culture-dependent methods were combined for the first time to study the microbiota and the function of the principle microorganisms in IRWQ. The glucoamylase, amylase and protease contents of IRWQ were 1.17, 1.55 and 2.87-times greater, respectively, than those of traditional wheat Qu. Like traditional wheat Qu, the main volatile flavor compounds in IRWQ were alcohols; however, the esters content was much higher and the acids content was much lower. Single molecule real-time DNA sequencing technology identified 18 fungal species and 59 bacterial species in IRWQ. Then, 30 species were isolated by culture-dependent methods. These species represented about 80% of the total fungal microbiota and 35% of the total bacteria microbiota. Molds were the main contributors of glucoamylase, amylase and protease activities. Aspergillus flavus had the highest glucoamylase and protease activity. Bacillus subtilis and Bacillus amyloliquefaciens also produced high hydrolytic enzyme activities. Saccharomyces cerevisiae produced the largest amounts of aromatics compounds, alcohols, esters and acids. Aldehydes and ketones are mainly produced by molds.