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Coffee fermentation is crucial for flavor and aroma, as microorganisms degrade mucilage and produce metabolites. This study aimed to provide a basis for understanding the impact of microorganisms on Coffea arabica from Yunnan, China, during washed processing. The microbial community structure and differentially changed metabolites (DCMs) of C. arabica beans during washed processing were analyzed. The results indicated that the top five predominant microorganisms at the genera level were Achromobacter, Tatumella, Weissella, Streptococcus, and Trichocoleus for bacteria and Cystofilobasidium, Hanseniaspora, Lachancea, Wickerhamomyces, and Aspergillus for fungi. Meanwhile, the relative content of 115 DCMs in 36 h samples decreased significantly, compared to non-fermentation coffee samples (VIP > 1, p < 0.05, FC < 0.65), and the relative content of 28 DCMs increased significantly (VIP > 1, p < 0.05, FC > 1.5). Furthermore, 17 DCMs showed a strong positive correlation with microorganisms, and 5 DCMs had a strong negative correlation (p < 0.05, |r| > 0.6). Therefore, the interaction and metabolic function of microbiota play a key role in the formation of coffee flavor, and these results help in clarifying the fermentation mechanisms of C. arabica and in controlling and improving the quality of coffee flavor. [ABSTRACT FROM AUTHOR]

Developing an effective method to achieve stability and improve the quality of Tibetan tea has scientific significance. Aspergillus niger K1 isolated and identified from Tibetan tea was inoculated in unsterilized or sterilized tea leaves to develop the bioaugmented fermentation (BF) and normal fermentation (NF) processes of Tibetan tea. The results showed that BF resulted in infusions with a deeper color, a stronger aroma, and a thicker taste compared to NF. The dominant bacterium in BF was Staphylococcus (23.76%), while the dominant fungus was Blastobotrys adeninivorans (50.95%). Moreover, 859 metabolites were identified, and the level of 90 differentially changed metabolites (DCMs) in BF increased significantly (VIP > 1, p < 0.05, FC > 2) compared to those in NF, while the level of 37 DCMs in BF decreased significantly (VIP > 1, p < 0.05, FC < 0.5). Correlation analysis demonstrated that A. niger significantly positively correlated with theabrownins, caffeine, and glutamylisoleucine (p < 0.05, |r| > 0.8). B. adeninivorans showed significant negative correlations with 1-(beta-D-ribofuranosyl)-1,4-dihydronicotinamide and 2-hydroxyacetaminophen sulfate (p < 0.05, |r| > 0.8). Consequently, the inoculation of A. niger for BF has the potential to alter the metabolites in tea through a synergistic interaction with other microorganisms, ultimately improving the sensory quality of Tibetan tea. [ABSTRACT FROM AUTHOR]

Koji is an important starter for rice shochu brewing and influences the rice shochu quality. Consequently, we studied the impacts of koji on the flavor compounds and sensory characteristics of rice shochu using molds Aspergillus kawachii SICC 3.917 (A-K), Aspergillus oryzae SICC 3.79(A-O), Aspergillus Niger CICC 2372 (A-N), Rhizopus oryzae CICC 40260 (R-O), and the traditional starter Qu (control). The effects of koji on the aroma components, free amino acids (FAAs), and overall sensory aspects of rice shochu were studied. These findings indicated that koji significantly affected the rice shochu's quality. The content of total FAAs in rice shochu A-K (30.586 ± 0.944 mg/L) and A-O (29.919 ± 0.278 mg/L) was higher than others. The content of flavor compounds revealed that the aroma of rice shochu with various koji varied greatly from the smells of alcohols and esters. Shochu A-O had a higher concentration of aroma compounds and it exhibited a strong aroma and harmonious taste compared with the others. This research using taste compounds, FAAs, flavor intensity, and partial least squares regression (PLSR) showed that shochu A-O appeared to possess the best sensory qualities, with elevated concentrations of alcohols and sweet FAAs and lesser concentrations of sour FAAs. Therefore, the A-O mold is promising for the manufacture of rice shochu with excellent flavor and sensory characteristics. [ABSTRACT FROM AUTHOR]

Aspergillus amstelodami A1 isolated from Pu-erh tea was inoculated in sterilized or unsterilized sun-dried green tea leaves to develop pure culture fermentation and enhanced fermentation (EF) of Pu-erh tea. The results showed that the content of tea polyphenols and five catechins in tea decreased significantly, and the content of thearubigins and theabrownins increased significantly after pure culture fermentation. Compared with natural fermentation, the levels of soluble sugars and theabrownins in EF were significantly higher, whereas the levels of gallic acid, (+)-catechin, (-)-epicatechin, (-)-epigallocatechin and caffeine were significantly lower; the scores of sensory evaluation including appearance, color of infusion, taste, aroma and infused leaves in EF were significantly higher; while the value of a* and b* of EF's tea infusion were higher and the value of L* was lower. A. amstelodami A1 didn't become the dominant fungi in EF, while the microbial communities in EF were different from those in NF. Therefore, the enhanced fermentation by inoculation of A. amstelodami A1 changed the chemical components of tea leaves through the synergistic effect with other microorganisms, therefore improving the sensory quality of Pu-erh tea. [ABSTRACT FROM AUTHOR]

The current study employed a combination of high-throughput sequencing and non-targeted metabolomics techniques to elucidate the changes in the quality, microbial communities, and metabolites throughout the fermentation process of traditional Midu Juanti , a traditional fermented meat product that originates from ethnic minority regions in southwestern China. The findings show that 22 dominant genera (7 bacterial and 15 fungal genera), with a relative abundance >1%, were successfully identified during the fermentation of Midu Juanti. Additionally, 979 metabolites were identified using the Human Metabolome Database (HMDB) annotation. Among these, lipids and lipid-like molecules constituted the largest proportion, followed by organic acids and their derivatives. Moreover, based on the variable importance in the projection (VIP) > 2 and P < 0.05, 60 differentially changed metabolites (DCMs) were identified. Meanwhile, the presence of Lactobacillus was positively correlated with 54 DCMs (P < 0.05, |r| > 0.5), including tryptophyl-threonine and (5R)-5-hydroxyhexanoic acid. Conversely, a negative correlation was observed between the presence of Monascus and these 54 DCMs (P < 0.05, |r| > 0.5). This study has the potential to enhance the processing theory of fermented meat products and establish a solid theoretical foundation for the control and enhancement of the quality of Midu Juanti. • Co-fermentation of plant derived and animal as raw materials of Midu Juanti. • The microbial community and metabolic characteristics of Midu Juanti was revealed. • Lactobacillus , Monascus and Pichia were dominant microorganisms in Midu Juanti. • The metabolic profile consists mainly of lipids and lipid-like molecules. • Lactobacillus , Monascus and Pichia showed strong correlation with metabolites. [ABSTRACT FROM AUTHOR]

[Display omitted] • P. chrysogenum used in pure-culture and enhanced fermentation of Pu-erh tea. • 69 compounds in enhanced fermentation were significantly lower. • 40 compounds in enhanced fermentation were significantly higher. • Inoculation with P. chrysogenum changed the composition of the fungal community. • Inoculation with P. chrysogenum improved the sensory quality of Pu-erh tea. Developing an effective method to improve the quality of Pu-erh tea is of great scientific and commercial interest. In this work, Penicillium chrysogenum P1 isolated from Pu-erh tea was inoculated in sterilized or unsterilized sun-dreid green tea leaves to develop pure-culture fermentation (PF) and enhanced fermentation (EF) of Pu-erh tea. Spectrophotometry and high performance liquid chromatography determined that contents of free amino acids (FAA), total tea polyphenols and eight polyphenolic compounds in PF were significantly lower than these in non-inoculation control test (CK) (P < 0.05), whereas the contents of soluble sugars and theabrownins (TB) in PF were significantly higher (P < 0.05) than in CK. A total of 416 volatile compounds were detected by headspace solid-phase micro-extraction combined with gas chromatography-mass spectrometry. Comparison to CK, 124 compounds in PF were degraded or decreased significantly [Variable importance in projection [(VIP) > 1.0, P < 0.05, fold change (FC) < 0.5], whereas 110 compounds in PF were formed or increased significantly (VIP > 1.0, P < 0.05, FC > 2). Compared with normal fermentation (NF), the levels of gallic acid, (+)-catechin, (−)-epicatechin and 64 volatile compounds in EF were significantly lower (VIP > 1.0, P < 0.05, FC < 0.5), whereas the levels of FAA and 39 volatile compounds were significantly higher (VIP > 1.0, P < 0.05, FC > 2). Amplicon sequencing of fungal internal transcribed spacer 1 (ITS1) revealed that P. chrysogenum P1 didn't become the dominant fungus in EF; while the fungal communities in EF were different from those in NF, in that the relative abundances of Blastobotrys bambusae and P. chrysogenum in EF were higher, and the relative abundances of Aspergillus niger and Kluyveromyces marxianus in EF were lower. Overall, inoculation of P. chrysogenum in unsterilized sun-dreid green tea leaves changed the the fungal communities in fermentation of Pu-erh tea, and chemical compounds in fermented tea leaves, i.e., the levels of TB and the compounds responsible for the stale flavor, e.g., 2-amino-4-methoxybenzothiazole were increased, resulting in improvement of the sensory quality, including mellower taste and stronger stale flavor. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aspergillus luchuensis is a non-toxigenic fungus in fermentation of pu-erh tea. • The genome of A. luchuensis was sequenced and annotated. • Enzymes related to hydrolysis and O-methylation of phenolics were identified. • Knowledge of functions and mechanisms of A. luchuensis were advanced. Aspergillus fungi are extensively used in traditional food fermentation, so their functions, mechanisms, and safety risks are worth exploring. In this study, a dominant fungal strain (P1) was isolated from a fermented pu-erh tea and identified as A. luchuensis by phylogenetic analysis of fungal internally-transcribed spacer sequencing, partial β-tubulin and calmodulin genes. A pure-strain fermentation of tea leaves was developed, and tea compounds were analyzed by widely-targeted metabolomics, using high-performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC-MS). The mycotoxins, aflatoxin (B1, B2, M1 and M2), fumonisin B1 and B2, ochratoxin A, citrinin, were not detected in fermented tea leaves using methods in the National Standard of the Peoples' Republic of China. The genome of 36.60 Mb with 11,836 protein-coding genes was sequenced by PacBio sequencing and annotated. Expression of fungal genes during fermentation was analyzed by Illumina HiSeq 2500; genes encoding enzymes including glycoside hydrolases, phenolic acid esterases, laccases, tyrosinases, dehydrogenases, peroxidases, dioxygenases, monooxygenases, decarboxylases and O-methyltransferases were identified. These enzymes catalyze hydrolysis, oxidation, ring cleavage, hydroxylation, decarboxylation and O-methylation of phenolic compounds , significantly (p < 0.05) changing the phenolic compound composition. While, phenolic compounds were degraded through degradation of aromatic compounds pathways and xenobiotics biodegradation and metabolism pathways. These findings advance knowledge of the functions and mechanisms of action of Aspergillus in traditional food fermentation. [ABSTRACT FROM AUTHOR]