Hong Qu Research Articles

Analysis of the flavour components, total phenolic content and antioxidant capacity between rice wine from two raw rice and starters

SummaryDifferent raw rice and starters will affect the quality of Chinese rice wine (CRW). This study focused on the quality (flavour components, total phenolic content and antioxidant capacity) between Hong Qu japonica rice wine and Wheat Qu glutinous rice wine. Free amino acids and volatile compounds were analysed respectively. Total phenolic content was compared using Folin–Ciocalteu methods and antioxidant activity using DPPH, ABTS+ and FRAP methods. The results indicated that total free amino acid content of CRW ranged from 0.959 ± 0.09 to 3.229 ± 0.24 g L−1. About 65 volatile compounds were obtained in wine samples, mainly including alcohols, esters, aldehydes, acids, phenols and ethers. Isopentanol, isobutanol, phenylethyl alcohol, ethyl lactate, diethyl succinate, benzaldehyde, furfural and 2,4‐ditert‐butylphenol were the prominent aroma components in samples. Total phenolic content in samples ranged from 0.27 ± 0.00 to 0.45 ± 0.01 mg GAE mL−1. Experimental samples showed different radical scavenging capacity and ferric‐reducing capacity. These results proved that japonica rice wine with Hong Qu had abundant flavour components and strongest antioxidant capacity, the brewing raw material can be better developed in the production of CRW.

Effects of Main Nutrient Sources on Improving Monascus Pigments and Saccharifying Power of Monascus purpureus in Submerged Fermentation

Hong Qu (HQ), obtained through fermentation of various grains using Monascus spp., has been widely utilized as the main and characteristic initial saccharification and traditional fermentation starter in the food brewing industry. The quality, color, and flavor of HQ and HQ wine are closely related to the saccharifying power (SP) and Monascus pigments (MPs) of Monascus spp. In this study, to optimize the culture medium in submerged fermentation by M. purpureus G11 for improving SP and MPs, the effects of carbon source, nitrogen source, inorganic salts, and vitamins on SP activity and biosynthesis of MPs were explored through single-factor analysis and response surface Box–Behnken experiments. The results showed that the optimal medium composition was 6.008% rice powder, 1.021% peptone, 0.0049% CuSO4, and 0.052% vitamin B1. Validation experiments performed under the optimized fermentation conditions showed a significant increase in MPs and SP by 14.91% and 36.24%, with maximum MPs and SP reaching 112.61 and 365.12 u/mL, respectively. This study provides a theoretical basis for enhancing MPs and SP in M. purpureus for HQ production, to improve the production efficiency and shorten the production cycle of HQ-related fermentation products.

Metabolomics Analysis Coupled with Weighted Gene Co-Expression Network Analysis Unravels the Associations of Tricarboxylic Acid Cycle-Intermediates with Edible Pigments Produced by Monascus purpureus (Hong Qu).

Monascus azaphilones pigments (MonAzPs) produced by microbial fermentation are widely used as food chemicals for coloring and supplying beneficial biological attributes. In this study, a fermentation perturbation strategy was implemented by separately adding different amino acids, and detecting the intracellular metabolome via UHPLC-Q-Orbitrap HRMS. With the aid of weighted gene co-expression network analysis, two metabolic intermediates, fumarate and malate, involved in the tricarboxylic acid cycle, were identified as the hub metabolites. Moreover, exogenous addition of fumarate or malate significantly promoted red pigment production, and reduced orange/yellow pigment production. The importance of the tricarboxylic acid cycle was further emphasized by detecting intracellular levels of ATP, NAD(P)H, and expression of oxidoreductase-coding genes located in the MonAzPs synthetic gene cluster, suggesting a considerable effect of the energy supply on MonAzPs synthesis. Collectively, metabolomics is a powerful approach to position the crucial metabolic regulatory factors, and facilitate the development of engineering strategies for targeted regulation, lower trial-and-error cost, and advance safe and controllable processes for fermented food chemistry industries.

Understanding of microbial diversity in three representative Qu in China and characterization of the volatile compounds in the corresponding Chinese rice wine

Microbial diversity of three typical Qu in China, Jimo wheat Qu from Shandong province (WQJM), Shaoxing wheat Qu from Zhejiang province (WQSX), and Gutian Hong Qu from Fujian province (GTHQ), was compared by Illumina-based sequencing. Then volatile compounds in rice wine were analyzed by FlavourSpec® to illustrate correlation between rice wine flavor and microbes in Qu. Results showed that the microbial diversity was WQJM > WQSX > GTHQ, and the dominant microbiota in each Qu varied greatly. Saccharopolyspora, Staphylococcus and Aspergillus were the main microorganisms in WQSX. Microbes in WQJM distributed relatively even, and Pantoea, Bacillus, Pediococcus, Staphylococcus, Weissella, Aspergillus, Rhizopus, Thermoascus, and Saccharomyces were dominated. In GTHQ, Pantoea, Klebsiella, Burkholderia, and Monascus were major microbial floras. Correlation analysis indicated that Corynebacterium, Klebsiella, Pantoea, Wickerhamomyces, and Mucor in WQSX were mainly correlated with producing esters including ethyl hexanoate, isoamyl acetate, ethyl pyruvate. Brevibacterium, Klebsiella, Brachybacterium, Aspergillus, Penicillium, and Xeromyces in WQJM were strongly related with aldehydes, alcohols and ketones represented by benzaldehyde, ethanol, heptan-2-one. In GTHQ, Burkholderia, Weissella, Aspergillus, Candida, Davidiella, Alternaria and Saccharomyces were closely correlated with butan-1-ol, 2-pentanone, dimethyl sulfide. The different microbiota in Qu caused variation of metabolism during brewing, and lead to the distinguished flavor of rice wine.

Microbial Communities and Flavor Compounds during the Fermentation of Traditional Hong Qu Glutinous Rice Wine.

As a traditional Chinese rice wine, Hong Qu glutinous rice wine (HQW) is popular among consumers due to its unique flavor. However, its quality changes during fermentation, and the potential relationships between flavor and microbes have not been systematically researched. In this work, physicochemical properties (pH, total sugar, alcohol, amino acid nitrogen), flavor compounds (organic acids, free amino acids, and volatile compounds), and microbial communities were investigated. The results revealed that Pantoea, Lactiplantibacillus, Lactobacillus, Leuconostoc, and Weissella predominated the bacterial genera, and Monascus was the predominant fungal genus. Organic acids, free amino acids, and key volatile compounds (esters and alcohols) significantly increased during fermentation. The correlations analysis showed that Lactiplantibacillus was closely associated with flavor compounds formation. This study deepens our understanding of the roles of microorganisms in flavor formation on traditional HQW fermentation.

Effect of Hong Qu on the flavor and quality of Hakka yellow rice wine (Huangjiu) produced in Southern China

This study aimed to investigate effect of Hong Qu on flavor and quality of Hakka yellow rice wine (Hakka Huangjiu). Volatile components of three kinds of Hakka Huangjiu with or without adding Hong Qu were analyzed by solid phase microextraction-gas chromatography-mass spectrometry. Their non-volatile components were also detected by liquid chromatography quadrupole Orbitrap mass spectrometry (LC-Q-Orbitrap-MS). Results indicated that there were great differences in flavor components among three wines. Among them, the main difference components between traditional Hakka Huangjiu and Hakka Huangjiu without adding Hong Qu were isoamyl alcohol, phenylethanol, isobutyl acetate, isobutyl alcohol, ethyl palmitate and ethyl decanoate. In Hakka Huangjiu, esters were the most volatile components, followed by alcohols, while acids were less. Under NEG and POS modes of LC-Q-Orbitrap-MS, a total of 765 and 1244 components were detected in three kinds of Hakka Huangjiu, respectively. Among 217 kinds of polypeptides detected, the content of 160 kinds of polypeptides in Hakka Huangjiu adding only with Hong Qu was higher than that of traditional Hakka Huangjiu and Hakka Huangjiu without adding Hong Qu. Amino acids and polypeptides contents in Hakka Huangjiu brewed only with Hong Qu and traditional Hakka Huangjiu co-fermented with Hong Qu were relatively high.

Regional characteristics and discrimination of the fermentation starter Hong Qu in traditional rice wine brewing

SummaryHong Qu (HQ) is a fermentation starter used to brew Hong Qu rice wine (HQ wine). The regional characteristics and discrimination of HQ are not fully understood. This study elucidates fermentation characteristics of HQ through sensory evaluation and the analysis of six physicochemical characteristics of HQ wine brewed by twenty‐nine HQ from different regions. Results showed that the complex physicochemical indices of HQ wine would be reduced to three principal components – total acidity, total sugars and non‐sugar solids by principal component analysis. Twenty‐nine HQ samples were classified into four clusters by hierarchical cluster analysis – Cluster A, B, C and D. Cluster B only included Gutian HQ (GTQ) brewing base liquors with a fresh and soft taste, the highest sensory scores and low coefficient of variation (CV). The rest three Clusters mainly included Wuyi HQ (WYQ) brewing base liquors with full‐bodied and tasteful flavours, high CV values and different sensory scores. WYQ could brew more good and less below standard liquors, while the quality of HQ wine brewed using GTQ was more even than that of WYQ. Conclusively, the geographical location and processing technology of HQ are the main external factors contributing to the regional characteristics of HQ wine.

The Potential of Flos sophorae immaturus as a Pigment-Stabilizer to Improve the Monascus Pigments Preservation, Flavor Profiles, and Sensory Characteristic of Hong Qu Huangjiu.

Hong Qu Huangjiu (HQW) is distinguished by its inclusion of Monascus pigments, meaning that photosensitivity strongly affects the sensory quality of the wine. In this study, the effects of Flos sophorae immaturus (FSI) on the stability of Monascus pigments, the flavor profiles, and the sensory characteristics of HQW were investigated. After sterilization, the addition of FSI increased the preservation rate of Monascus pigments in HQW by up to 93.20%, which could be accounted for by the synergy of rutin and quercetin in FSI. The total content of the volatile flavor compounds in HQW increased significantly as the added amounts of FSI were increased, especially 3-methyl-1-butanol, 2-methyl-1-propanol, and short-chain fatty acid ethyl esters (SCFAEE). Sensory evaluation and partial least-squares regression revealed that the concentration of FSI significantly affected the aroma characteristics of HQW but had little effect on the mouthfeel. The addition of 0.9 mg/mL FSI yielded a satisfactory HQW with high scores in terms of mouthfeel and aroma. The strong correlation between fruit-aroma, full-body, and SCFAEE suggests that FSI might alter the aroma of HQW by enhancing the synthesis of SCFAEE. Summarily, treatment with FSI represents a new strategy for improving the stability of photosensitive pigments and thus adjusting the aroma of HQW or similar beverages.

Structural characterization and immunomodulatory activity of mycelium polysaccharide from liquid fermentation of Monascus purpureus (Hong Qu)

Alkaline extracted endopolysaccharides (MPS) from Monascus purpureus (Hong Qu) mycelium were successfully separated into four sub-fractions, namely MPS-1 (18.0 %), MPS-2 (27.1 %), MPS-3 (12.6 %) and MPS-4 (14.7 %), by DEAE-Cellulose column chromatography. By combining monosaccharide composition analysis, methylation analysis and 1D & 2D NMR, the structure of sub-fractions was systematically characterized. Both MPS-1 and MPS-2 were comprised of mannose, glucose and galactose in the molar ratio of 1.5:1.6:1.0 and 10.6:1.0:13.8, respectively. The backbone of them both consisted of 2-α-Manp with several different branched chains. However, MPS-1 contained glucose based sugar residues such as 3-Glcp and 4-Glcp which were not shown on MPS-2. The proposed structures of MPS-3 and MPS-4 were not obtained due to the fairly complex molecular structure and relatively low yield. Moreover, based on the RAW 264.7 cells model, MPS-2 could significantly promote cytokines secretion including IL-6, TNF-α, and IL-10 and improve expression levels of the related mRNA.

Fungal community diversity and fermentation characteristics in regional varieties of traditional fermentation starters for Hong Qu glutinous rice wine

Hong Qu glutinous rice wine (HQ wine) is a traditional alcoholic beverage produced in China by fermenting cooked rice using a fermentation starter prepared with the fungus Monascus purpureus. This starter (Hong Qu, HQ) is made empirically by open spontaneous fermentation that is hard to control and standardize, resulting in inconsistent wine quality. This study investigates representative HQ samples from a large geographic region. It explores fungal microbiome compositions, identifies characteristic differences important for the production of various HQ wine styles, and reveals the key fungi responsible for HQ wine fermentation characteristics. The source of the HQ inoculum was found to be the main factor influencing fungal community composition and diversity, followed by processing technology and geographical distribution. Linear discriminant analysis effect size (LEfSe) uncovered 14 genera as potential biomarkers to distinguish regional varieties of HQ. Significant differences were also found in fermentation characteristics such as liquefying power (LP), saccharifying power (SP), fermenting power (FP), total acid content (TA) and liquor-producing power (LPP). The key fungi responsible for LP (5 genera), SP (3 genera), FP (1 genera), LPP (4 genera), and TA (4 genera) were determined using redundancy correlation analysis. Finally, Spearman’s correlation analysis indicated that LPP shows a strong positive correlation with FP and LP, while TA displays a strong negative correlation with FP. The results of this study may be utilized to prepare consistently high quality, next-generation HQ by better controlling fungal community structures, and to design fermentation processes for HQ wines with desirable oenological characteristics.

Screening and evaluation of Monascus purpureus FJMR24 for enhancing the raw material utilization rate in rice wine brewing.

The rapid development of the rice wine industry has increased the demand for raw materials worldwide. A fungal strain with good adaptability to rice wine brewing conditions, which can also enhance the utilization rate of raw materials (URRM), thus increasing the production efficiency, was sought in the present research. The strain FJMR24 was successfully isolated and screened from 35 fermentation starters and exhibited high amylase activity (2200.9 ± 18.5 U g-1 ) and high glucoamylase activity (2330.4 ± 31.9 U g-1 ). Based on a morphological examination and a sequence analysis of the internal transcribed spacer (ITS) gene and β-tubulin gene, FJMR24 was identified as Monascus purpureus, which is an edible and versatile fungus that plays a dominant role in the processing of Hong Qu. A moderate pH of 5-6 under incubation at 35 °C for 5-6 days was favorable for the growth and enzyme production of FJMR24. The strain could also tolerate the extreme conditions of 15-45 °C, 18% ethanol (v/v), and an acidity of pH 2. The excellent fermentation adaptability of FJMR24 might enable it to retain high enzyme activity during rice wine brewing. As a result of the action of FJMR24, the URRM of the base liquor increased by around 26% due to increased starch hydrolysis efficiency, which was mainly due to the high unit enzyme activity of FJMR24. This study provides perspectives for the application of a M. purpureus strain with high starch hydrolysis activity for enhancing the URRM in traditional rice wine brewing. © 2020 Society of Chemical Industry.

Microbial communities and amino acids during the fermentation of Wuyi Hong Qu Huangjiu

Wuyi Hong Qu Huangjiu (WHQHJ) is produced in an open, non-sterile environment, but this can lead to a too bitter taste. The aim of this study was to determine the change of microbial communities and amino acids during traditional fermentation at different temperatures and elucidate the potential correlation between microbes and amino acids. The results showed that the bitter, sweet, umami, and astringent amino acid contents all tended to increase during fermentation. Temperature had an effect on amino acid content and bitter taste, and the higher the temperature, the greater the content of amino acids and perceptual intensity of bitterness. Microbiological analysis was performed using high-throughput sequencing technology based on rRNA gene sequencing. It demonstrated that there were significant differences between the fungal and bacterial communities during the fermentation process at 20 °C, 25 °C, and 30 °C based on both principal component analysis and hierarchical clustering analysis. A high correlation (|r| > 0.6, P < 0.05) between microbes and amino acids was determined by redundancy correlation, Spearman correlation and network analysis. Finally, six genus were the key microbes responsible for bitter amino acids during fermentation. To conclude, these findings show the importance of understanding the mechanism of bitter amino acid production.

Comparison of microbial communities and amino acid metabolites in different traditional fermentation starters used during the fermentation of Hong Qu glutinous rice wine

Hong Qu glutinous rice wine (HQGRW) is produced from glutinous rice with the addition of the traditional fermentation starter Hong Qu (mainly Gutian Hong Qu and Wuyi Hong Qu) has been added. It is unpalatable and rejected by consumers because the bitter and umami tastes are too high. The objective of this study was to compare the dynamics of the microbial communities and amino acids especially those in the different traditional fermentation starters used during HQGRW fermentation, and elucidate the key microbes responsible for amino acids. Three widely-used types of Hong Qu starters were used which can make different bitterness and umami in our previous studies, namely, black Wuyi Hong Qu (WB), red Wuyi Hong Qu (WR), and Gutian Hong Qu (GT). The living dynamics of fungal and bacterial communities during the fermentation were determined by high-throughput sequencing and rRNA gene sequencing technology for the first time. The content of amino acids in the HQGRW were determined by reverse-phase high-performance liquid chromatography analysis. The results showed that there were differences between fungal communities during the fermentation process in Wuyi Hong Qu and Gutian Hong Qu starters and between bacterial communities during the fermentation process in the three types of starters. The amino acid content of the samples showed an increasing trend in each group. The total amino acids, as well as the bitter, sweet, umami, astringent amino acids, in the GT Hong Qu group increased more slowly during fermentation, as comparerd to those in WB and WR groups. Furthermore, Meyerozyma, Saccharomyces, Bacillus, Rhizopus, Pediococcus, Monascus, and Halomonas were strongly positively correlated with the content of bitter and umami amino acids (|r| > 0.6 with FDR adjusted P < 0.05) by Spearman’s correlation analysis. To conclude, these findings may contribute to a better understanding of the bitter and umami amino acid production mechanism during traditional fermentation and helpful in improving the taste of HQGRW.

Amino acid and microbial community dynamics during the fermentation of Hong Qu glutinous rice wine

Hong Qu glutinous rice wine (HQGRW) is typically very bitter after fermentation due to the presence of bitter amino acids (BAA). The amino acids are considered to primarily derive from the hydrolysis of protein from the raw material by microbial populations during fermentation, and temperature also has an important effect on bitter tastes. Here, the dynamics of fungal and bacterial communities during the traditional fermentation of HQGRW were investigated using high-throughput sequencing and RNA-based rRNA gene sequencing. Both principal component analysis (PCA) and hierarchical clustering analysis (HCA) revealed significant differences between the fungal and bacterial communities during fermentation at 20 °C and those performed at 25 °C and 30 °C. The growth of Saccharomyces and some LAB apparently inhibited the growth of several pernicious bacterial taxa including acetic acid bacteria. The amino acid contents of the samples all increased continuously under the different temperature conditions. Moreover, higher temperatures were associated with higher perceptual intensity of bitterness and contents of amino acids including bitter, sweet, umami, and astringent type amino acids as well as the total amino acid content during fermentation. Furthermore, the total BAA content was strongly and positively correlated with Pediococcus, Saccharomyces, Lactobacillus, Monascus, and Halomonas relative abundances, with correlations identified by |r| > 0.6 with P adjusted P < 0.05. In conclusion, these results contribute to a better understanding of the mechanisms underlying BAA production during the traditional fermentation of HQGRW and will help improve the quality and safety of these wines.

Structural characterisation and immunomodulatory activity of exopolysaccharides from liquid fermentation of Monascus purpureus (Hong Qu)

As a traditional Chinese medicinal and edible fungus, Monascus has been widely studied for its secondary metabolites such as Monascus pigments and γ-aminobutyric acid. However, the exopolysaccharides have not been extensively studied and this has limited their food and industrial applications. In this study, exopolysaccharides isolated from the liquid fermentation of Monascus purpureus (Hong Qu) were successfully separated into two fractions (EPS-1 and EPS-2) by DEAE-Cellulose column chromatography. A possible pigment-exopolysaccharides complex was identified. The molecular structure of the polysaccharides portion was systematically investigated using the combined techniques of FT-IR, monosaccharide analysis, methylation analysis and 1D & 2D NMR. Monosaccharide compositional analysis showed that EPS-1 was composed of mannose, glucose and galactose in the molar ratio of 8:1:11, while EPS-2 consisted of six different monosaccharides, namely, rhamnose, arabinose, xylose, mannose, glucose and galactose, with the molar ratio of 2.2:1.9:1:5.6:1.9:7.7, respectively. Moreover, the backbone of EPS-1 mainly consisted of 5-β-D-Galf (31.74 wt%) and 2-β-D-Manp (17.48 wt%) with other sugar residues including 2,6-β-D-Galf, T-α-D-Manp, 6-α-D-Manp and 3,5-β-D-Galf also detected at small percentages. Furthermore, the immunomodulatory activity of EPS-1 was investigated by RAW 264.7 cell lines. The cell proliferation and pinocytosis activity, cytokines releasing, NO production and related mRNA levels all have been determined. The results indicated that EPS-1 could significantly promote cytokines secretion including IL-6, TNF-α, and IL-10 and improve expression levels of the related mRNA.

Dynamic changes of total acid and bacterial communities during the traditional fermentation of Hong Qu glutinous rice wine

Abstract Background Hong Qu glutinous rice wine (HQGRW) is brewed under non-aseptic fermentation conditions, so it usually has a relatively high total acid content. The aim of this study was to investigate the dynamics of the bacterial communities and total acid during the fermentation of HQGRW and elucidate the correlation between total acid and bacterial communities. Results The results showed that the period of rapid acid increase during fermentation occurred at the early stage of fermentation. There was a negative response between total acid increase and the rate of increase in alcohol during the early fermentation stage. Bacterial community analysis using high-throughput sequencing technology was found that the dominant bacterial communities changed during the traditional fermentation of HQGRW. Both principal component analysis (PCA) and hierarchical clustering analysis revealed that there was a great difference between the bacterial communities of Hong Qu starter and those identified during the fermentation process. Furthermore, the key bacteria likely to be associated with total acid were identified by Spearman's correlation analysis. Lactobacillus, unclassified Lactobacillaceae, and Pediococcus were found, which can make significant contributions to the total acid development (| r | > 0.6 with FDR adjusted P Conclusions This was the first study to investigate the correlation between bacterial communities and total acid during the fermentation of HQGRW. These findings may be helpful in the development of a set of fermentation techniques for controlling total acid. How to cite: Liang Z, Lin X, He Z, et al. Dynamic changes of total acid and bacterial communities during the traditional fermentation of Hong Qu glutinous rice wine. Electron J Biotechnol 2020;43. https://doi.org/10.1016/j.ejbt.2019.12.002

The dynamics of volatile compounds and their correlation with the microbial succession during the traditional solid-state fermentation of Gutian Hong Qu glutinous rice wine

Gutian Hong Qu glutinous rice wine (GHQW) is a representative alcoholic beverage in China. During its traditional brewing process, multiple strains are involved. However, the roles of these microorganisms, particularly their contributions to aroma formation, are poorly understood. Therefore, in this study, the dynamics of volatile components and microbial succession during the traditional fermentation process of GHQW were monitored, by using HS-SPME-GC/MS and high throughput 16 S rRNA and ITS sequencing techniques. Following a 32-day semi-open solid-state fermentation, massive changes in volatile profile and microbial communities were observed. Based on these, the potential correlations between volatile components and microorganisms during the fermentation were explored by using Pearson correlation analysis. It was revealed that 3 bacterial taxa, including Lactococcus lactis, Burkholderia gladioli and Cronobacter helveticus, and 5 fungal taxa, including Wickerhamomyces anomalus, Saccharomyces cerevisiae, Aspergillus vitricola, Aspergillus penicillioides and Monascus purpureus, showed strong connections with various volatile components. Thus these bacteria and fungi might play crucial roles in volatile components biosynthesis, and thus were preliminary considered as core functional microorganisms for GHQW brewing. The detailed information on the dynamic changes of volatile components and microbial communities throughout GHQW brewing can further expand our understanding of the formation mechanisms of GHQW aroma.

Changes in Cold and Hot Syndrome and Gastrointestinal Bacterial Community Structure in Mice by Intervention with Food of Different Nature.

To reveal the effect of foods with different natures on cold or hot syndrome and gastrointestinal bacterial community structure in mice. Forty-five 6-week-old male ICR Kunming mice of clean grade were divided into 5 groups, 9 per group, including the control (CK), hot nature herbs (HM), Hong Qu glutinous rice wine (RW), tea rice wine (TW), and cold nature herbs (CM) groups. Distilled water or corresponding herbs were administered to mice (0.01 mL/g body weight) in the 5 groups by gastric infusion respectively, once daily for 28 d. Appearance, behavior, and serum biochemical indicators, including 5-hydroxytryptamine (5-HT), thyroid stimulating hormone (TSH), noradrenaline (NE), cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), the hot nature index, as well as the gastrointestinal bacterial community structure were analyzed in all groups after treatment. After supplementation for 28 d, CM and TW mice showed different degrees of cold syndrome, and HM and RW mice showed different degrees of hot syndrome. Compared with the HM and RW mice, the TSH, NE, cAMP levels and hot nature indices in the CM and TW mice were significantly decreased and 5-HT and cGMP levels were significantly increased (P<0.05). There was no obvious change in appearance or behavior in CK mice. Results of clustering analysis showed that the gastrointestinal bacterial community structures were highly similar in TW and CM mice as well as in RW and HM mice, and that they were from the same branch, respectively, when the distance was 0.02. The key microbes associated with cold syndrome were Lachnospiraceae uncultured, Lactococcus, etc., and the key microbes associated with hot syndrome were S24-7 norank, Ruminococcaceae uncultured, etc. CONCLUSION: The interventions with different nature foods could change cold or hot syndrome in mice, leading to changes in gastrointestinal bacterial community structure.

Microbial communities and volatile metabolites in different traditional fermentation starters used for Hong Qu glutinous rice wine

Hong Qu glutinous rice wine (HQGRW), as one of the most typical representatives of Chinese rice wine, is generally brewed from glutinous rice by adding two traditional wine fermentation starters—Hong Qu (HQ) and Bai Qu (BQ). The objective of this study was to determine the microbial communities and volatile metabolites of different traditional fermentation starters for HQGRW, and elucidate the potential correlation between microbiota and volatile metabolites. Both heatmap and principal component analysis (PCA) revealed the significant variances in volatile profiles among different wine starters. Microbiological analysis based on high-throughput sequencing (HTS) technology demonstrated that both of bacterial and fungal communities varied significantly in different starters. HQ was dominated mainly by bacteria of Bacillus ginsengihumi (20.17%), Pantoea sp. (10.39%), Elizabethkingia sp. (5.52%), Streptococcus sp. (5.03%) Brevundimonas sp. (3.03%), Rickettsia prowazekii (2.94%), Thermus thermophilus (2.54%), Bacillus amyloliquefaciens (1.48%), Bacillus aryabhattai (1.42%); fungi of Monascus purpureus (39.7%), Aspergillus niger (27.35%), Xeromyces bisporus (8.39%), Aspergillus penicillioides (6.89%), Aspergillus flavus (2.33%) and Pichia farinose (0.79%). By contrast, BQ contained much higher proportions of bacteria of Lactococcus lactis (10.45%), Lactobacillus brevis (9.99%), Pediococcus pentosaceus (8.29%), Weissella paramesenteroides (6.69%), Lactobacillus fermentum (4.83%), Gluconobacter thailandicus (3.93%), Lactobacillus alimentarius (3.59%), fungi of Rhizopus arrhizus (31.47%), Saccharomycopsis fibuligera (27.86%), Aspergillus niger (20.81%), Issatchenkia orientalis (3.79%), Saccharomycopsis malanga (3.15%), Clavispora lusitaniae (2.29%), Candida tropicalis (1.47%), Saccharomyces cerevisiae (1.11%) and Rhizopus microsporus (0.57%). Furthermore, core functional microbiota that might contribute to volatile flavour development was explored through Spearman's correlation-based network analysis. Lactobacillus brevis, Lactobacillus alimentarius, Lactobacillus plantarum and Aspergillus niger were found to be strongly associated with acid compounds (FDR adjusted P < 0.01), while Pichia sp., Candida sp., Monascus purpureus, Lactobacillus brevis and Lactobacillus alimentarius were positively correlated with concentrations of aromatic esters associated with fruity and floral notes (FDR adjusted P < 0.01), implying that these microorganisms might make significant contributions to the flavour of rice wine. These findings demonstrated that the aromatic quality of HQGRW may be critically influenced by the microbiota in traditional fermentation starters. To conclude, this study would contribute to the development of novel defined starter cultures for improving the aromatic quality of HQGRW.

Exploring core functional microbiota responsible for the production of volatile flavour during the traditional brewing of Wuyi Hong Qu glutinous rice wine

The objective of this study was to explore the core functional microbiota for the production of volatile flavour during the traditional brewing of Wuyi Hong Qu glutinous rice wine, one of the most typical representatives of rice wine in China. Microbiological analysis based on high-throughput sequencing (HTS) technology demonstrated that bacteria of Lactobacillus, Bacillus, Leuconostoc, Lactococcus, Raoultella, Staphylococcus, Pediococcus, and Weissella, and fungi of Saccharomyces, Saccharomycopsis, Rhizopus, Monascus, Pichia, Wickerhamomyces, Candida, and Aspergillus were the predominant genera during the traditional fermentation process. Principal component analysis (PCA) based on the relative abundance showed that both of bacterial and fungal communities varied significantly in different fermentation phases. Some predominant microbial species or genera (including bacteria of Bacillus spp., Staphylococcus spp., Weissella spp., and P. acidilactici, and fungi of M. purpureus, R. oryzae, R. arrhizus var. arrhizus, and A. niger) were detected at the initial brewing stage, and their populations decreased as the fermentation progressed, while those of Lactobacillus, Gluconacetobacter, Leuconostoc, Pichia, Wickerhamomyces, and Saccharomyces increased to become the predominant genera at the final stage. A total of 79 volatile compounds were identified in traditional fermentation starters and during the traditional brewing process, mainly including esters, alcohols, acids, aldehydes, ketones, and phenols. Heatmaps and PCA also revealed the significant variances in the composition of volatile compounds among different samples. Furthermore, the potential correlations between microbiota succession and volatile flavour dynamics were explored through bidirectional orthogonal partial least squares (O2PLS) based correlation analysis. Three bacterial genera, namely, Gluconacetobacter, Lactobacillus, Lactococcus, and three fungal genera of Pichia, Wickerhamomyces, and Saccharomyces, were determined as the core functional microbiota for production of main volatile compounds in Wuyi Hong Qu glutinous rice wine. To conclude, information provided by this study is valuable to the development of effective strategies for the selection of beneficial bacterial and fungal strains to improve the quality of Wuyi Hong Qu glutinous rice wine.