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

Analyzing the contribution of top-down and bottom-up methods to the construction of synthetic microbial communities in Jiuyao

The construction of synthetic microbial communities is a crucial strategy for improving the stability of microbial populations and the quality of fermented foods. Jiuyao, an essential saccharification and fermentation starter in Huangjiu production, was the focus of this study. Using metagenomics combined with culture-dependent methods, we identified 11 microbial species involved in Huangjiu fermentation. Through metagenomic analysis and simulated fermentation, Rhizopus delemar, Rhizopus microspores, Rhizopus stolonife, Rhizopus azygosporus, Saccharomycopsis fibuligera, Saccharomyces cerevisiae, Wickerhamomyces anomalus and Pediococcus pentosaceus were determined to be the core microbial species driving the Jiuyao fermentation process. A synthetic microbial community was constructed based on these species, successfully reproducing the flavor and sensory qualities of Huangjiu while enhancing fermentation efficiency. This study provides valuable insights into the functional roles of Jiuyao-associated microbes and offers a framework for improving microbial community stability and fermentation quality in Huangjiu production.

Impact of Polygonum orientale L. flower addition on microbial community of Xiaoqu and volatile compounds of Huangjiu in Fangxian, China

Fangxian Huangjiu is a Chinese rice wine fermented by the unique local starter Xiaoqu with the addition of Polygonum orientale L. (P. orientale L.) flower. This research aimed to elucidate the influence of P. orientale flower on the enzyme activity and microbial community of Fangxian Xiaoqu, and consequently on the physicochemical indicators and volatiles of Fangxian Huangjiu. The results revealed that the P. orientale flower significantly enhanced the acid protease activity and declined the α-amylase activity of Xiaoqu. Additionally, it improved microbial community diversity and the species of the dominant bacterial genus in Xiaoqu. For fermentation broth, the types of volatile substances have improved. Furthermore, Spearman correlation analysis revealed that Pediococcus, Kosakonia, Saccharomycopsis, Mucor, Cyberlindnera, and Wickerhamomyces were closely related to the synthesis of volatiles. These findings clarify the role of P. orientale flower and provide the practical basis for the future production of Fangxian Xiaoqu.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-025-01829-8.

Generation of a synthetic autochthonous microbiota responsible for the essential flavors and brewing properties of Daqu

Based on the 26 strains of medium-high-temperature Daqu, seed microbial inocula and mature microbial inoculants were prepared and inoculated into crushed wheat to prepare cleaner medium-high-temperature Daqu (XQ). The physicochemical properties, flavor, and microbial profile of XQ were studied using traditional medium-high-temperature Daqu (CQ) or industry standards as controls. The results showed that the liquefaction ability, saccharification activity, esterification activity, and moisture content of XQ were better than those of Daqu industry standards. The results of GC-MS and E-nose analyses showed that the main flavor compounds in the two types of Daqu were esters, alcohols, acids, and aldehydes, which had similar flavor profiles. Microbial sequencing revealed that the most abundant fungi in XQ were Aspergillus subflavus, Wickerhamomyces anomalus, Rhizopus oryzae, and Candida tropicalis, whereas the most abundant bacteria were Lactobacillus curvatus, Weissella cibaria, and Bacillus subtilis. Both types of Daqu contained a high abundance of W. anomalus. In addition, the COG (Clusters of Orthologous Groups of Proteins) analyses displayed that the two types of Daqu had their dominant functions and generally had the pathways and functional characteristics of organism growth and metabolism. This study laid some experimental research bases for the preparation of cleaner Daqu and could provide insights for producing safer microbial fermented foods.

The Addition of Glutamine Enhances the Quality of Huangjiu by Modifying the Assembly and Metabolic Activities of Microorganisms during the Fermentation Process

In this study, the effects of adding glutamate (Glu), glutamine (Gln), aspartate (Asp), and asparagine (Asn) on the flavor formation of Huangjiu were investigated, and the effect of Gln concentration on the quality, microbial community structure, and flavor development of Huangjiu was further explored. Varied Gln concentrations influenced yeast growth, sugar utilization, microbial communities, and quality attributes. Additional Gln promoted yeast cell counts and sugar depletion. It increased the complexity of bacterial co-occurrence networks and reduced the impact of stochastic processes on assembly. Correlation analysis linked microorganisms to flavor compounds. Isolation experiments verified the role of Saccharomyces cerevisiae, Aspergillus chevalieri, Bacillus altitudinis, and Lactobacillus coryniformis in flavor production under Gln conditions. This research elucidated the microbiological mechanisms by which amino acid supplementation, especially Gln, enhances Huangjiu quality by modulating microbial metabolic functions and community dynamics during fermentation. This research is significant for guiding the production of Huangjiu and enhancing its quality.

Transcriptome Analysis Reveals the Variations in Enzyme Production of Saccharopolyspora rosea A22 under Different Temperatures

Saccharopolyspora is a key microorganism in the fermentation of traditional fermented foods, capable of producing saccharifying and liquefying enzymes at elevated temperatures. However, the specific mechanisms and regulatory pathways governing Saccharopolyspora's response to ambient temperatures are not yet fully understood. In this study, the morphological differences in Saccharopolyspora rosea screened from traditional handmade wheat Qu at different temperatures were initially explored. At 37 °C, the mycelium exhibited abundant growth and radiated in a network-like pattern. As the temperature increased, the mycelium aggregated into clusters. At 50 °C, it formed highly aggregated ellipsoidal structures, with the mycelium distributed on the spherical surface. Subsequently, we assessed the biomass, saccharifying enzyme activity and liquefying enzyme activity of Saccharopolyspora rosea cultured at 37 °C, 42 °C and 50 °C. Furthermore, transcriptome analysis demonstrated that Saccharopolyspora rosea employs mechanisms related to the carbon metabolism, the TCA cycle, glycine, serine and threonine metabolisms, and microbial metabolism in diverse environments to coordinate its responses to changes in environmental temperature, as verified by the expression of typical genes. This study enhances our understanding of the differences in high-temperature enzyme production by Saccharopolyspora, and offers valuable guidance for the traditional fermented food industry to drive innovation.

Environmental factors drive microbial community succession in biofortified wheat Qu and its improvement on the quality of Chinese huangjiu

Wheat Qu plays the role of saccharification fermentation, providing microorganisms and flavor in the fermentation of huangjiu, and the use of functional microorganisms to fortify wheat Qu is becoming increasingly popular. Yet, the mechanisms promoting microbial successions of wheat Qu remain unclear. In this study, we first correlated microbial community succession with physicochemical factors (moisture, temperature, acidity, glucoamylase and amylase) in inoculated raw wheat Qu (IRWQ) with Saccharopolyspora rosea. The Mantel test was performed to investigate the significance and found that temperature (r = 0.759, P = 0.001), moisture (r = 0.732, P = 0.006), and acidity (r = 0.712, P = 0.017) correlated significantly with the bacterial community in phase 1 (0-40 h). Meanwhile, temperature correlated significantly with the fungal community in phases 1 and 2 (40-120 h). To confirm the effect of temperature on microbial communities, the artificial reduction of bio-heat (37°C) in IRWQ also reduced the relative abundance of heat-resistant microorganisms including Bacillus and Saccharopolyspora. A higher abundance of Saccharopolyspora (87%) in IRWQ was observed following biofortified inoculation of S. rosea, in which glucoamylase activity increased by 40% compared to non-inoculated raw wheat Qu (NIRWQ) (1086 U/g vs 776 U/g). Finally, the IRWQ was employed to mechanized huangjiu fermentation and it was found to reduce the bitter amino acid and higher alcohol content by 27% and 8%, respectively, improving the drinking comfort and quality of huangjiu.

Environmental Factors Affecting the Diversity and Composition of Environmental Microorganisms in the Shaoxing Rice Wine Producing Area

Shaoxing rice wine is a notable exemplar of Chinese rice wine. Its superior quality is strongly correlated with the indigenous natural environment. The results indicated that Firmicutes (75%), Actinobacteria (15%), Proteobacteria (5%), and Bacteroidetes (3%) comprised the prevailing bacterial groups. Among the main bacterial genera, Lactobacillus was the most abundant, accounting for 49.4%, followed by Lactococcus (11.9%), Saccharopolyspora (13.1%), Leuconostoc (4.1%), and Thermoactinomyces (1.1%). The dominant fungal phyla were Ascomycota and Zygomycota. Among the dominant genera, Saccharomyces (59.3%) prevailed as the most abundant, followed by Saccharomycopsis (10.7%), Aspergillus (7.1%), Thermomyces (6.2%), Rhizopus (4.9%), Rhizomucor (2.2%), and Mucor (1.3%). The findings demonstrate that the structure of the bacterial and fungal communities remains stable in the environment, with their diversity strongly influenced by climatic conditions. The continuous fluctuations in environmental factors, such as temperature, air pressure, humidity, rainfall, and light, significantly impact the composition and diversity of microbial populations, particularly the dominant bacterial community.

Integrated meta-omics approaches reveal Saccharopolyspora as the core functional genus in huangjiu fermentations

Identification of the core functional microorganisms in food fermentations is necessary to understand the ecological and functional processes for making those foods. Wheat qu, which provides liquefaction and saccharifying power, and affects the flavor quality, is a key ingredient in ancient alcoholic huangjiu fermentation, while core microbiota of them still remains indistinct. In this study, metagenomics, metabolomics, microbial isolation and co-fermentation were used to investigate huangjiu. Although Aspergillus is usually regarded as core microorganism in wheat qu to initiate huangjiu fermentations, our metagenomic analysis showed that bacteria Saccharopolyspora are predominant in wheat qu and responsible for breakdown of starch and cellulose. Metabolic network and correlation analysis showed that Saccharopolyspora rectivirgula, Saccharopolyspora erythraea, and Saccharopolyspora hirsuta made the greatest contributions to huangjiu's metabolites, consisting of alcohols (phenylethanol, isoamylol and isobutanol), esters, amino acids (Pro, Arg, Glu and Ala) and organic acids (lactate, tartrate, acetate and citrate). S. hirsuta J2 isolated from wheat qu had the highest amylase, glucoamylase and protease activities. Co-fermentations of S. hirsuta J2 with S. cerevisiae HJ resulted in a higher fermentation rate and alcohol content, and huangjiu flavors were more similar to that of traditional huangjiu compared to co-fermentations of Aspergillus or Lactiplantibacillus with S. cerevisiae HJ. Genome of S. hirsuta J2 contained genes encoding biogenic amine degradation enzymes. By S. hirsuta J2 inoculation, biogenic amine content was reduced by 45%, 43% and 62% in huangjiu, sausage and soy sauce, respectively. These findings show the utility of Saccharopolyspora as a key functional organism in fermented food products.

Research Progress on Flavor and Quality of Chinese Rice Wine in the Brewing Process

Chinese rice wine (CRW) is a traditional and unique alcoholic beverage in China, favored by many consumers for its rich aroma, unique taste, and complex ingredients. Its flavor is primarily composed of volatile and nonvolatile compounds. These flavor compounds are partly derived from grains and starters (Qu), while the other part is produced by microbial metabolism and chemical reactions during the brewing process. Additionally, ethyl carbamate (EC) in CRW, a hazardous chemical, necessitates controlling its concentration during brewing. In recent years, numerous new brewing techniques for CRW have emerged. Therefore, this paper aims to collect aroma descriptions and thresholds of flavor compounds in CRW, summarize the relationship between the brewing process of CRW and flavor formation, outline methods for reducing the concentration of EC in the brewing process of CRW, and summarize the four stages (pretreatment of grains, fermentation, sterilization, and aging process) of new techniques. Furthermore, we will compare the advantages and disadvantages of different approaches, with the expectation of providing a valuable reference for improving the quality of CRW.

Dynamic analysis of volatile metabolites and microbial community and their correlations during the fermentation process of traditional Huangjiu (Chinese rice wine) produced around Winter Solstice

Traditional Huangjiu produced around Winter Solstice has higher quality and a more harmonious aroma. To investigate the variations of volatile metabolites and microbial communities during fermentation, gas chromatography-ion migration chromatography (GC-IMS), gas chromatography-mass spectroscopy (GC-MS) and high-throughput sequencing were employed. Aroma compounds results showed that alcohols and phenols increased before 45 days of fermentation and then decreased after 45 days, while esters gradually increased. Fungal genera Saccharomyces, Aspergillu, and Rhizomucor were dominant, whereas Staphylococcus, Pediococcus and Weissella were the dominant bacterial genera in the late stage. In addition, 11 genera such as Lactobacillus, Saccharopolyspora and Aspergillus (|r| > 0.6, p < 0.05) may contributed to traditional Huangjiu ecosystem stability. Moreover, correlation analysis indicated the dominant microorganisms (Saccharopolyspora, Staphylococcus, Lactobacillus, Saccharomyces and Aspergillus) were positively correlated with key compounds. These results provided theoretical guidance for further study on the flavor regulation of traditional Huangjiu via microbial community level and microbial augmentation.

Investigation on fresh bamboo replacing rice husks for brewing light-aroma Baijiu

Husks are the main source of bran and furfural flavor in traditional Chinese light-aroma Baijiu, but they negatively affect its smell and taste. Here, bran husks were replaced with fresh bamboo to brew light-aroma Baijiu. Flavor components in Jiupei and Baijiu were detected through headspace solid-phase microextraction with gas chromatography-mass spectrometry, and physicochemical properties were assessed; flavor results were obtained from correlation, principal component, and cluster analyses. Starch and reducing sugar content in Jiupei negatively correlated with moisture, alcohol content, and acidity. Fresh bamboo reduced furfural from bran husks in Jiupei by 88.5% and increased alcohol distillation by 51%; it also improved starch efficiency (5%). Surprisingly, isovanillin was found to be present in Baijiu. Total Baijiu yield (57% ± 2.01%) was attained when crushed bamboo size was 1.5 cm × 0.3 cm × 0.3 cm. This study supports the use of fresh bamboo (an eco-friendly alternative for husks) in brewing light-aroma Baijiu. PRACTICAL APPLICATION: The use of fresh bamboo as a replacement for rice husks in brewing light-aroma Baijiu was investigated. It attenuated the chaff taste in light-aroma Baijiu and increased the liquor yield. Surprisingly, isovanillin was also present in the base Baijiu, and it added to the fragrance. This study not only supports the use of bamboo as an auxiliary material for brewing light-aroma Baijiu but also provides a reference for brewing light-aroma Baijiu with alternative auxiliary materials.

Analysis of the Microbial Community Structure and Volatile Metabolites of JIUYAO in Fangxian, China

JIUYAO is an important saccharification starter in the production of huangjiu and is also an important source of flavor. In this study, the microbial community structure of JIUYAO from Fangxian was studied by high-throughput sequencing (HTS) technology for the first time. The volatile flavor compounds of the JIUYAO metabolites were also analyzed by headspace solid-phase microextraction combined with full two-dimensional gas chromatography-mass spectrometry (HS-SPME-GC×GC/MS) for the first time. The results showed that there were 15 dominant bacterial genera, including Weissella, Pediococcus, unclasssified_k_norank_d_Bacteria, Lactobacillus, Leuconostoc, etc. Thirteen species of dominant fungi included Wickerhamomyces, Saccharomycopsis, Rhizopus, etc. The different samples of JIUYAO were similar in their microbial species, but the number of species was significantly different. A total of 191 volatile flavor compounds (VFCs) were detected, among which esters, alcohols, acids, and alkenes were the main flavor compounds, and 21 terpenoids were also detected. In addition, the functional prediction of micro-organisms in JIUYAO revealed that global and overview maps, amino acid metabolism, and carbohydrate metabolism were the dominant categories. Through correlation analysis, 538 potential correlations between the dominant micro-organisms and the different flavor compounds were obtained. This study revealed the interactions between the micro-organisms and the volatile metabolites in JIUYAO, which provided reliable data for the analysis of the microbial community structure of Fangxian JIUYAO and provided theoretical support for the quality evaluation of JIUYAO.

Developing an innovative raw wheat Qu inoculated with Saccharopolyspora and its application in Huangjiu

BACKGROUND

Mechanized Huangjiu is a stable product, is not subject to seasonal production restrictions, and markedly reduces labor intensity compared to traditional manual Huangjiu. However, the bitterness of mechanized Huangjiu impedes its further development.

RESULTS

Based on process optimization, when the fermentation temperature was 45 °C and the fermentation time was 122 h, the inoculation amount of Saccharopolyspora was 5%, the amount of added water was 26%, and the glucoamylase and amylase activities of wheat Qu increased by 27% and 40% respectively, compared with those before optimization. Huangjiu fermented by raw wheat Qu inoculated with Saccharopolyspora rosea F2014 showed a significant (P < 0.05) decrease in bitter amino acid content (1.24 vs. 2.86 g L^-1 , a decrease of 56%), which attenuated its bitterness.

CONCLUSION

An innovative fermentation process of inoculating Saccharopolyspora into raw wheat Qu was developed for the first time. Such a process could be used to control bitterness based on raw wheat Qu inoculated with Saccharopolyspora rosea F2014, instead of traditional wheat Qu in Huangjiu fermentation. © 2022 Society of Chemical Industry.

Complete genome sequence, metabolic model construction, and huangjiu application of Saccharopolyspora rosea A22, a thermophilic, high amylase and glucoamylase actinomycetes

Saccharopolyspora is an important microorganism in the fermentation process of wheat qu and huangjiu, yet the mechanisms by which it performs specific functions in huangjiu remain unclear. A strain with high amylase and glucoamylase activities was isolated from wheat qu and identified as Saccharopolyspora rosea (S. rosea) A22. We initially reported the whole genome sequence of S. rosea A22, which comprised a circular chromosome 6,562,638 bp in size with a GC content of 71.71%, and 6,118 protein-coding genes. A functional genomic analysis highlighted regulatory genes involved in adaptive mechanisms to harsh conditions, and in vitro experiments revealed that the growth of S. rosea A22 could be regulated in response to the stress condition. Based on whole-genome sequencing, the first genome-scale metabolic model of S. rosea A22 named iSR1310 was constructed to predict the growth ability on different media with 91% accuracy. Finally, S. rosea A22 was applied to huangjiu fermentation by inoculating raw wheat qu, and the results showed that the total higher alcohol content was reduced by 12.64% compared with the control group. This study has elucidated the tolerance mechanisms and enzyme-producing properties of S. rosea A22 at the genetic level, providing new insights into its application to huangjiu.

Analysis of Microbial Community, Volatile Flavor Compounds, and Flavor of Cigar Tobacco Leaves From Different Regions

Despite the booming international trade in cigar tobacco leaves (CTLs), the main characteristics of tobacco leaves from different producing areas are rarely reported. This study aimed to characterize the microbial community, volatile flavor compounds (VFCs), and flavor of CTLs from four famous cigar-producing areas, including Dominica, Brazil, Indonesia, and China. High-throughput sequencing results showed that the dominant genera in CTLs were Staphylococcus, Pseudomonas, Aspergillus, Sampaiozyma, and Alternaria. Sensory analysis revealed that Indonesian and Chinese CTLs were characterized by leathery, peppery, and baked aroma. Brazilian CTLs were dominated by caramel and herb aroma. Dominican CTLs had aromas of milk, fruity, sour, cream, flower, nutty, and honey. Supplemented with the determination of volatile flavor compounds (VFCs), the flavor of CTLs could be scientifically quantified. Most of these VFCs were aldehydes and ketones, and 20 VFCs showed significant differences in CTLs from different regions. The microbial community, VFCs, and flavor of CTLs vary widely due to geographic differences. Network analysis revealed the microbial community was closely related to most VFCs, but the relationships between the fungal community and VFCs were less than the bacterial community, and most of them were negative. Furthermore, it also found that the bacterial community had a greater contribution to the flavor of CTLs than the fungal community. This study obtained essential information on CTLs, which laid a foundation for deeply excavating the relationship between microbes and VFCs and flavor, and establishing a tobacco information database.

Microbial succession and exploration of higher alcohols-producing core bacteria in northern Huangjiu fermentation

Higher alcohols (HAs) are abundant compounds that provide important flavors in Huangjiu, but they also cause hangover. Previous studies have shown the production of HAs to be related to yeast, but the correlations between HAs and other microorganisms are rarely reported. In this study, we detected changes in levels of HAs and microbial dynamics during the Huangjiu fermentation process. Relationships were characterized using Pearson’s correlation coefficient. The functional core HA-producing bacteria were selected by bidirectional orthogonal partial least squares (O2PLS). The result showed that 2-methyl-1-propanol, phenethyl alcohol and 3-methyl-1-butanol were the principle HAs present at high levels. Lactococcus and Saccharomyces were predominant at the genus level of bacteria and fungi, respectively. A total of 684 correlations between HAs and microorganisms were established. Five genera were screened as functional core HA-producing bacteria. Our findings might provide some new inspiration for controlling the content of HAs, enhancing international prestige and market expansion of Huangjiu.

Interaction and Application of Molds and Yeasts in Chinese Fermented Foods

Fermentation is an ancient food preservation and processing technology with a long history of thousands of years, that is still practiced all over the world. Fermented foods are usually defined as foods or beverages made by controlling the growth of microorganisms and the transformation of raw and auxiliary food components, which provide the human body with many beneficial nutrients or health factors. As fungus widely used in traditional Chinese fermented foods, molds and yeasts play an irreplaceable role in the formation of flavor substances and the production of functional components in fermented foods. The research progress of molds and yeasts in traditional Chinese fermented foods from traditional to modern is reviewed, including the research on the diversity, and population structure of molds and yeasts in fermented foods. The interaction between fermenting mold and yeast and the latest research results and application development prospects of related industries were discussed.

Metagenomics-based insights into the microbial community profiling and flavor development potentiality of baijiu Daqu and huangjiu wheat Qu

Daqu and wheat Qu are saccharification and fermenting agents in Chinese huangjiu and baijiu production. This study aimed to investigate the difference between Daqu and wheat Qu in physicochemical indices, microbial communities, functional genes, and the metabolic network of key microbes responsible for flavor synthesis by whole-metagenome sequencing and metabolite analysis. Herein, physicochemical indices indicated that compared with wheat Qu, Daqu exhibited higher protease and cellulase activity and acidity, and lower glucoamylase and amylase enzyme activity. Metagenomic sequencing reveals that although Daqu and wheat Qu community composition have significant differences at species level, they have similar functional genes. Daqu were enriched in Pediococcus pentosaceus, Weissella paramesenteroides, Rasamsonia emersonii and Byssochlamys spectabilis (22.48% of the total abundance), while wheat Qu harbored greater abundances of Saccharopolyspora (54.78%, Saccharopolyspora rectivirgula, Saccharopolyspora shandongensis, Saccharopolyspora hirsuta, Saccharopolyspora spinose, and Saccharopolyspora erythraea). From a functional perspective, the important functions of Daqu and wheat Qu are both amino acid metabolism and carbohydrate metabolism. Meanwhile, a combined analysis among microbiota, functional genes, and dominant flavors indicated S. shandongensis, S. rectivirgula, and S. spinose might be the main contributor to the synthesis of flavor compounds in wheat Qu, while R. emersonii, W. paramesenteroides, Leuconostoc citreum, Leuconostoc mesenteroides, Weissella cibaria and P. pentosaceus may make the greatest contribution to flavor compounds synthesis in Daqu. This study reveals the microbial and functional dissimilarities of Daqu and wheat Qu, and helps elucidating different metabolic roles of microbes during flavor formation.

Enzyme Production Potential of Penicillium oxalicum M1816 and Its Application in Ferulic Acid Production

The present study focused on isolating an efficient enzyme production microorganism for ferulic acid (FA) production from wheat bran. A wild-type cellulase-, xylanase-, and feruloyl esterase-producing strain was isolated and identified as Penicillium oxalicum M1816. The genome was sequenced and assembled into 30.5 Mb containing 8301 predicted protein-coding genes. In total, 553 genes were associated with carbohydrate metabolism. Genomic CAZymes analysis indicated that P. oxalicum M1816, comprising 39 cellulolytic enzymes and 111 hemicellulases (including 5 feruloyl esterase genes), may play a vital role in wheat bran degradation and FA production. The crude enzyme of strain M1816 could release 1.85 ± 0.08 mg·g-1 FA from de-starched wheat bran (DSWB) at 12 h, which was significantly higher than other commercial enzymes. Meanwhile, when the strain M1816 was cultured in medium supplemented with DSWB, up to 92.89% of the total alkali-extractable FA was released. The process parameters of solid-state fermentation were optimized to enhance enzyme production. The optimized wheat bran Qu of P. oxalicum M1816 was applied to huangjiu fermentation, and the FA content was increased 12.4-fold compared to the control group. These results suggest that P. oxalicum M1816 is a good candidate for the development of fermented foods bio-fortified with FA.

Development of a novel multi-strain wheat Qu with high enzyme activities for Huangjiu fermentation

BACKGROUND

Wheat Qu has long been used as a fermentation starter to produce Huangjiu. Wheat Qu quality depends on its microbial community structure and the hydrolytic enzymes generated by the micro-organisms.

RESULTS

Strain YF1 and YF2 were successfully screened as they exhibited high acidic protease (231.9 ± 1.4 U g^-1 ) and cellulase (7.1 ± 0.6 U g^-1 ) activities. Based on a morphological and sequence analysis of the internal transcribed spacer (ITS) gene, YF1 and YF2 were identified as Rhizopus oryzae and Aspergillus niger, respectively. Cooked wheat Qu was produced using mixed fungal starter fermentations with Aspergillus oryzae SU-16, YF1, and YF2. For Qu-making, the optimized conditions for fermentation time, water content, and inoculum size were 47.8 h, 69.4%, and 6.1%, respectively. Under these conditions, compared with single-strain cooked wheat Qu, enzyme activities of amylase, acidic protease, and cellulase increased by 27.4%, 657.1%, and 1276.2%, respectively. Short peptides and free amino acids contents increased by 19.6% and 131.8%, respectively. This wheat Qu was used for Huangjiu brewing, and the alcohol content increased by approximately 14.6% because of the increased starch hydrolysis efficiency mainly attributed to its high enzyme activity.

CONCLUSION

Using mixed fungal strains as starter cultures may be an efficient strategy to improve wheat Qu quality, with great potential for application in industrial Huangjiu production. © 2021 Society of Chemical Industry.

Prebiotic, Probiotic, Antimicrobial, and Functional Food Applications of Bacillus amyloliquefaciens

Bacillus amyloliquefaciens belongs to the genus Bacillus and family Baciliaceae. It is ubiquitously found in food, plants, animals, soil, and in different environments. In this review, the application of B. amyloliquefaciens in probiotic and prebiotic microbes in fermentation, synthesis, and hydrolysis of food compounds is discussed as well as further insights into its potential application and gaps. B. amyloliquefaciens is also a potential microbe in the synthesis of bioactive compounds including peptides and exopolysaccharides. In addition, it can synthesize antimicrobial compounds (e.g., Fengycin, and Bacillomycin Lb), which makes its novelty in the food sector greater. Moreover, it imparts and improves the functional, sensory, and shelf life of the end products. The hydrolysis of complex compounds including insoluble proteins, carbohydrates, fibers, hemicellulose, and lignans also shows that B. amyloliquefaciens is a multifunctional and potential microbe which can be applied in the food industry and in functional food processing.