Analysis of Fungal Diversity, Physicochemical Properties and Volatile Organic Compounds of Strong-Flavor Daqu from Seven Different Areas.

Strong-flavor Daqu, as a fermentation agent, plays a significant role in shaping the quality of strong-flavor baijius, and fungal species in Daqu are important factors affecting the quality of Daqu. Therefore, we selected strong-flavor Daqu from seven different origins to study the fungal composition and the effects of the fungal composition on the physicochemical properties and volatile organic compounds (VOCs). It was found that the fungal composition influences the physicochemical properties of Daqu. Specifically, there was a positive link between Rhizomucor, Rhizopus, Thermomyces, and liquefying activity and a positive correlation between Aspergillus and fermenting activity. Furthermore, the relationships between esterifying activity and Thermomyces, Rhizomucor, Aspergillus, Pichia, and Saccharomycopsis were found to be positive. The VOCs in Daqu were affected by Aspergillus, Issatchenkia, Pichia, and Thermoascus. Issatchenkia was significantly positively correlated with benzeneethanol as well as Aspergillus and pentadecanoic acid ethyl ester, ethyl myristate. Pichia and Thermoascus were significantly negatively correlated with benzaldehyde and 2-furaldehyde. This study deepens our understanding of the relationship between VOCs, the physicochemical properties with microbial communities, and reference significance for the production of better-quality strong-flavor Daqu.

Lactiplantibacillus plantarum A72, a Strain with Antioxidant Properties, Obtained through ARTP Mutagenesis, Affects Caenorhabditis elegans Anti-Aging.

This research endeavored to elucidate the antioxidant attributes of lactic acid bacteria, specifically their impact on anti-aging and lifespan augmentation in Caenorhabditis elegans. The study focused on Lactiplantibacillus plantarum A72, identified through ARTP mutagenesis for its potent antioxidant properties. In vitro analysis affirmed its free radical neutralizing capacity. In C. elegans, the strain not only extended the lifespan by 25.13% and amplified motility 2.52-fold, but also maintained reproductive capabilities. Remarkably, Lpb. plantarum A72 diminished reactive oxygen species (ROS) and malondialdehyde (MDA) levels in C. elegans by 34.86% and 69.52%, respectively, while concurrently enhancing its antioxidant enzyme activities. The strain also bolstered C. elegans survival rates by 46.33% and 57.78% under high temperature and H2O2 conditions, respectively. Transcriptomic scrutiny revealed that Lpb. plantarum A72 could retard C. elegans aging and extend lifespan by upregulating the sod-5 and hsp-16.1 genes and downregulating the fat-6 and lips-17 genes. These findings propose Lpb. plantarum A72 as a potential antioxidant and anti-aging lactic acid bacteria.

Chemical Composition and Flavor Characteristics of Cider Fermented with Saccharomyces cerevisiae and Non-Saccharomyces cerevisiae.

Cider flavor has a very important impact on the quality. Solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) combined with gas chromatography-ion mobility spectrometry (GC-IMS) tested different kinds of non-Saccharomyces yeasts and Saccharomyces cerevisiae (S. cerevisiae) co-inoculated for the fermentation of cider to determine differences in aroma material, and the determination of odor activity value (OAV) is applied less frequently in research. Through Rhodotorula mucilaginosa, Debaryomyces hansenii, Zygosaccharomyces bailii, and Kluyveromyces Marxianus, four different strains of non-Saccharomyces yeast fermented cider, and it was found that, in both the chemical composition and flavor of material things, compared with monoculture-fermented cider using S. cerevisiae, all differences were significant. Co-inoculated fermentation significantly improved the flavor and taste of cider. As in the volatile compounds of OVA > 1, octanoic acid (Sc 633.88 µg/L, co-inoculation fermented group 955.49 µg/L) provides vegetable cheese fragrance and decanoic acid, ethyl ester (Sc 683.19 µg/L, co-inoculation fermented group 694.98 µg/L) a creamy fruity fragrance, etc., and the average content increased after co-inoculated fermentation. Phenylethyl alcohol, which can produce a rose scent, was relatively abundant in cider samples and varied greatly among the groups. Moreover, the contents of ethyl lactate and 1-butanol in the Sc+Rm (ciders fermented by S. cerevisiae and R. mucilaginosa) were the highest of all of the cider samples. Different types of non-Saccharomyces yeast produced cider with different flavor characteristics. This study demonstrates that different species of non-Saccharomyces yeast do have an important impact on the characteristics of cider and that co-inoculation with non-Saccharomyces yeast and S. cerevisiae for cider fermentation may be a strategy to improve the flavor of cider.

Effect of Autochthonous Lactic Acid Bacteria-Enhanced Fermentation on the Quality of Suancai.

The lactic acid bacteria (LABs) used for fermentation have an extremely vital impact on the quality of Suancai, a fermented vegetable. The bacterial diversity and metabolites of inoculated Suancai with LABs, including Lactiplantibacillus plantarum (Lb. plantarum), Levilactabacillus brevis (Lb. brevis), and Leuconostoc mesenteroides (Leu. mesenteroides), were investigated. The inoculation of LABs significantly decreased the pH and the content of nitrite. The Suancai inoculated with LABs had a higher content of the total titratable acidity (TTA) and organic acids than spontaneous fermentation. The LABs inoculation significantly influenced the bacterial community structures, which directly or indirectly caused changes of metabolites. The bacterial community profiles of Suancai inoculated with Lb. plantarum were more similar to spontaneous fermentation. The inoculation of Lb. plantarum, Lb. brevis, and Leu. mesenteroides could increase its abundance in Suancai. Whatever the species inoculated, Lb. plantarum was always the predominant bacterium in Suancai after fermentation. The inoculated LABs were positively correlated with most volatile compounds and amino acids. The inoculated LABs significantly improved the volatile compounds and amino acid content of Suancai. This study could contribute to understanding the function of starters in Suancai fermentation and promote the selection of applicable starters for high-quality Suancai production.