The differences in main components, enzyme activity, and microbial composition between substandard and normal jiuyao.

BACKGROUND: Jiuyao is a critical fermenting agent in traditional huangjiu brewing and it affects the quality of huangjiu. To assess and monitor the quality of jiuyao effectively we determined the differences between two common types of substandard jiuyao and normal jiuyao, with emphasis on the comparison of the main components, enzymatic activity, volatile substances, and microbial community structure. RESULTS: The water and starch content, acid protease activity, and esterification capability of type I substandard jiuyao were significantly lower than those of the normal jiuyao, and the protein contents, liquefaction capability, glycation capability, and neutral protease activity were substantially higher than those of the normal jiuyao. Type II substandard jiuyao had significantly lower indices than the normal group except for the starch and free amino acid content, which were significantly higher than those of the normal jiuyao. Significant differences were observed between substandard and normal jiuyao in the content of 21 volatile compounds. 2-Pentylfuran could be used as a marker of substandard jiuyao. Type I substandard jiuyao contained a higher abundance of aerobic Pediococcus and Marivita in comparison with the normal jiuyao. Type II substandard jiuyao consisted of a greater abundance of anaerobic Mucor and Staphylococcus. CONCLUSION: The quality of jiuyao was significantly affected by the water content. Due to the different abundances of aerobic and anaerobic bacteria in jiuyao, oxygen may also be an important parameter affecting the quality of jiuyao. We believe that the present study offers a theoretical basis for the evaluation and control of the quality of jiuyao. © 2023 Society of Chemical Industry.

[Community structure and diversity formation of fermentation fungi in traditional Shaoxing Huangjiu]. / ä¼ ç»Ÿç»å ´é»„é ’é ¿é€ çœŸèŒç¾¤è½ä¸Žå¤šæ ·æ€§å‘ç”Ÿæœºåˆ¶.

To reveal the formation mechanism of fungal community and diversity during the production of Shaoxing Huangjiu, we examined fungal communities in the samples of Linfanjiumu, Maiqu and fermentation mash based on Illumina MiSeq PE300 high-throughput sequencing platform. A total of 136000, 215283, 166150, and 143624 sequences were obtained from the samples of Linfanjiumu, Maiqu, initial mash and mature mash, respectively. After clustering, 32, 133, 107 and 84 OUT (operational taxonomic units) were obtained, respectively. The diversity and richness of fungi were in order of Maiqu > initial mash > mature mash > Linfanjiumu. At the level of phylum, Ascomycota were dominant in all samples. At genus level, Saccharomyces was dominant in Linfanjiumu, Aspergillus was dominant in Maiqu, and Saccharomyces and Aspergillus were the dominant fungi in the initial and mature mash. With the extension of the fermentation time, the proportion of Saccharomyces gradually increased in the mash, while other fungal groups including Aspergillus showed a decreasing trend. According to the results of PCoA analysis and similarity cluster analysis, the structure of fungi community in Linfanjiumu, initial mash and mature mash was much similar, while the fungal resources in Maiqu were quite different from other samples. The analysis of fungal community characteristics in the initial mash showed that the Linfanjiumu and Maiqu affected fungal diversity in Shaoxing Huangjiu. The dominant species of saccharification and fermentation starter (Linfanjiumu and Maiqu) played a leading role in driving community assembly of fermentation fungi.