Research progress on the brewing techniques of new-type rice wine

Assessment of wheat Qu fermented at medium and high temperatures: Effects of Bupleurum addition on fermentation characteristics, volatile profiles, and microbial communities

The quality of wheat Qu significantly influences rice wine production. However, quality control is often challenging due to variations in raw materials, preparation methods, and climatic conditions. Nevertheless, the impact of traditional northern Chinese craftsmanship techniques on the quality of wheat Qu remains largely unexplored, and addressing this gap is crucial for standardizing fermentation processes and optimizing rice wine production. In this study, we investigated the impact of traditional northern Chinese wheat Qu craftsmanship techniques on product quality by comparing the fermentation characteristics, volatile profiles, and microbiomes of three types of wheat Qu (medium-temperature wheat Qu without Bupleurum; medium-temperature wheat Qu with Bupleurum; and high-temperature wheat Qu with Bupleurum). We found that Bupleurum addition and thermal treatment can alter the microbial communities enriched in starters, enhancing fermentation performance and aroma characteristics. Additionally, we identified key aroma compounds and microbial biomarkers that could distinguish among different types of wheat Qu. Finally, statistical analyses and functional prediction assessments suggested that fungi likely drive microbial succession and metabolism in wheat Qu. These findings enable the development of strategies for optimizing wheat Qu production.

Novel insights into delayed bitterness control in traditional Huangjiu: Regulating bacterial community by inoculated with Saccharomyces cerevisiae SC-6

Under semi-open brewing conditions, traditional Huangjiu often suffers from unstable flavor quality, including occasional delayed bitterness. To address this issue, a yeast strain, Saccharomyces cerevisiae SC-6, was screened for its ability to reduce delayed bitterness. The effects of SC-6 on the flavor and microbial composition of Huangjiu exhibiting high levels of delayed bitterness were also investigated. GC-MS analysis indicated that S. cerevisiae SC-6 significantly lowered the levels of key delayed bitter compounds, including octanoic acid, ethyl caprylate, benzaldehyde, and phenol, by 54.80 %, 12.21 %, 31.38 %, and 43.23 %, respectively. PCoA analysis demonstrated that SC-6 altered the microbial community of traditional Huangjiu. Correlation analysis indicated that reduced bitter compounds correlated with changed abundances of Rhodopseudomonas, unclassified_f_Micromonosporaceae, Lachnoclostridium, Lactobacillus, Streptomyces, Clostridium_sensu_stricto_1, Staphylococcus, Pseudomonas, unclassified_o__Enterobacterales, and Candida. These results provide effective guidance for controlling off-flavors in traditional Huangjiu and clarify the role of microorganisms in the production of bitter substances.

Impact of Bacillus subtilis on Chinese yellow rice wine (Huangjiu) fermentation: Method variations and flavor analysis

This investigation explores the impact of various fermentation techniques and the inoculation of Bacillus subtilis spores on the physicochemical properties and principal flavor profiles of Huangjiu. Employing sensory analysis, headspace solid-phase microextraction, gas chromatography-tandem mass spectrometry (HS-SPME-GC-MS), and orthogonal partial least squares discriminant analysis (OPLS-DA), we observed that these variables significantly alter the physicochemical attributes of Huangjiu. Our analysis, integrating volatile organic compounds (VOCs) with odor activity values (OAV), revealed that while B. subtilis inoculation modifies the concentrations of key flavor compounds, it does not affect their types. Notably, the inoculation enhances the concentrations of 13 primary flavor compounds, thereby enriching floral and fruity notes while reducing higher alcohol levels. These findings contribute valuable insights into the flavor formation mechanisms of Huangjiu and guide the optimization of fermentation processes.

Interaction and dynamic changes of microbial communities and volatile flavor compounds during the fermentation process of coffee flower rice wine

To develop a unique flavor of rice wine, coffee flowers (by-products of the coffee industry) were added because of their biologically active compounds that are conducive to health, and the fermentation parameters were optimized. In addition, the dynamic changes of microbial communities and volatile flavor compounds (VFCs) during the different fermentation stages were investigated. After the optimization of the fermentation parameters, a novel product, i.e., the coffee flower rice wine (CFRW), was obtained with a bright yellow transparent, fragrant, and harmonious aroma and mellow and refreshing taste by sensory evaluation, when 4.62% of the coffee flowers and 1.93% koji were added and fermented at 24.10°C for 3.88 days. The results showed that Lactococcus was the dominant bacteria, accounting for 87.0-95.7%, while Rhizopus and Cladosporium were the main fungi, accounting for 68.2% and 11.3% on average, respectively, in the fermentation process of the CFRW. Meanwhile, twenty-three VFCs were detected in the CFRW, which included three alcohols, six terpenes, ten esters, three aromatics, and one furan. The correlation analysis revealed that there were 16 significant positive correlations and 23 significant negative correlations between the bacterium and VFCs (|ρ| > 0.6, p < 0.05), while there were 12 significant positive correlations and one significant negative correlation between the fungi and VFCs (|ρ| > 0.6, p < 0.05). Furthermore, five VFCs, including linalool, geraniol, ethyl acetate, 1-hexanol, and 3-methyl-1-butanol, contributed vital flavors to the CFRW, and they were all significantly negatively correlated with the changes of Massilia and Acinetobacter (|ρ| > 0.6, p < 0.05). Moreover a significant positive correlation was found between the relative abundance of Lactococcus and the contents of 3-methyl-1-butanol and ethyl acetate (|ρ| > 0.6, p < 0.05). Therefore, this study provides a valuable theoretical basis for further improving the quality and production technology of CFRW.

Discovery of electromagnetic polarization in Asian rice wine deterioration process and its applications

Rice wine, known as yellow wine in China and Japan, possesses considerable nutritional value and holds significant global influence. This study addresses the challenge of preserving rice wine, which is prone to rancidity due to its low alcohol content. Conventional storage techniques employing pottery jars often result in substantial spoilage losses. Through rigorous investigation, this research identifies a polarization phenomenon exhibited by degraded rice wine when subjected to high-frequency microwaves(>60GHz), presenting a pioneering method for detecting spoilage, even within sealed containers. Employing a multi-channel microwave radar apparatus, the study delves into the susceptibility of rice wine to electromagnetic waves across various frequencies, uncovering pronounced polarization traits in deteriorated samples within the E-band microwave spectrum. Furthermore, lab-controlled simulations elucidate a direct correlation between physicochemical alterations and high-frequency Radar Cross Section (RCS) signals during the wine's deterioration process. A novel six-membered Hydrated Cluster hypothesis is proposed, offering insights into the molecular mechanisms underlying this phenomenon. Additionally, dielectric property assessments conducted using vector network analyzers (VNA) reveal noteworthy enhancements in the dielectric constant of deteriorated rice wine, particularly within the high-frequency domain, thereby augmenting detectability. These findings carry implications for refining rice wine preservation techniques and contribute to the advancement of non-destructive testing technologies, enabling the detection of rice wine deterioration or indications thereof, even within sealed vessels.

Impact of Incorporating Shiitake Mushrooms (Lentinula edodes) on Microbial Community and Flavor Volatiles in Traditional Jiuqu

Jiuqu is one of the important raw materials for brewing Chinese rice wine (Huangjiu), often known as the "bone of wine". In this study, the microbial community and flavor substances of Jiuqu made with different amounts of shiitake mushroom (Lentinula edodes) were investigated through high-throughput sequencing technology and headspace gas chromatography-ion migration spectroscopy (HS-GC-IMS), using traditional wheat yeast as a control. The results showed that 1593 genera and 5507 species were identified among the four types of yeast, with Aspergillus and Paecilomyces being the most dominant microorganisms at the genus level. Carbohydrate, coenzyme, and amino acid metabolism may be the main metabolic processes of the dominant microorganisms in Jiuqu. In terms of flavor, a total of 79 volatile substance monomers and some dimers were detected from four types of Jiuqu raw materials, with the main substances being 12 aldehydes, 19 ketones, 13 alcohols, 19 esters, 4 olefins, 1 acid, 3 ethers, 4 furans, 1 pyrazine, 1 pyridine, 1 triethylamine, and 1 thiazole. The correlation results indicate that Aspergillus, Lactobacillus, and Vibrio correlate significantly with the volatile flavor compounds unique to shiitake mushrooms and also have a positive effect on alcohol, esters, and furans. These results could shed light on the selection of Lentinula edodes as a fermentation starter for Huangjiu in the Qinba Mountain area.

Correlation between changes in flavor compounds and microbial community ecological succession in the liquid fermentation of rice wine

Microorganisms play an important role in regulating flavor compounds in rice wine, whereas we often don't understand how did they affect flavor compounds. Here, the relations between flavor compounds and microbial community ecological succession were investigated by monitoring flavor compounds and microbial community throughout the fermentation stage of rice wine. The composition of microbial community showed a dynamic change, but 13 dominant bacterial genera and 4 dominant fungal genera were detected throughout the fermentation stages. Saccharomyces presented a strong negative correlation with fungi genera but had positive associations with bacteria genera. Similarly, flavor compounds in rice wine were also showed the dynamic change, and 112 volatile compounds and 17 free amino acids were identified in the whole stages. The alcohol-ester ratio was decreased in the LTF stage, indicating that low temperature boosts ester formation. The potential correlation between flavor compounds and microbial community indicated that Delftia, Chryseobacterium, Rhizopus and Wickerhamomyces were the core functional microorganisms in rice wine. These findings clarified the correlation between changes in flavor compounds and in microbial community in the liquid fermentation of rice wine, and these results have some reference value for the quality improvement and technological optimization in liquid fermentation of rice wine.

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.

The Production of Intensified Qu and Its Microbial Communities and Aroma Variation during the Fermentation of Huangjiu (Chinese Rice Wine)

In recent years, intensified Qu (IQ) has been gradually applied to brewing in order to improve the aroma of Huangjiu (Chinese rice wine). In this study, Saccharomyces cerevisiae and Wickerhamomyces anomalus solutions were added to Fengmi Qu (FMQ) from Fangxian, China to produce IQ, and brewing trial was conducted. High-throughput sequencing (HTS) was used to analyze the microbial community in fermentation broth of IQ (IQFB). Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and sensory evaluation were performed to analyze volatile aroma compounds (VACs) in sample without Qu and both fermentation broths. The results showed that Pediococcus, Cronobacter, Enterococcus, Weissella, and Acinetobacter and Saccharomycopsis, Wickerhamomyces, and Saccharomyces were dominant bacterial and fungal groups, respectively. A total of 115 VACs were detected, and the content of esters including ethyl acetate, isoamyl acetate, and so on was noticeably higher in IQFB. The finding of sensory evaluation reflected that adding pure yeast to Qu could enhance fruit and floral aromas. Correlation analysis yielded 858 correlations between significant microorganisms and different VACs. In addition, prediction of microbial community functions in IQFB revealed global and overview maps and carbohydrate metabolism to be the main one. This study is advantageous for further regulation of the fermentation process of Huangjiu by microbial means.

Unraveling the difference in flavor characteristics of Huangjiu fermented with different rice varieties using dynamic sensory evaluation and comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry

To investigate the specific differences in flavor characteristics of Huangjiu fermented with different rice varieties, dynamic sensory evaluation, comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) and multivariate statistical analysis were employed. Dynamic sensory evaluation methods including temporal dominance of sensations (TDS) and temporal check all that apply (TCATA) were applied to explore the differences and variations in sensory attributes. The sensory results showed that the intensity of astringency and post-bitterness in the Huangjiu fermented with glutinous rice was weaker while ester and alcoholic aroma were more prominent than the one fermented with japonica rice. The results of free amino acids and aroma compounds analysis indicated that the amino acids were mainly sweet and bitter amino acids, and some key aroma compounds were predominant in the Huangjiu fermented with glutinous rice, such as ethyl butyrate (OAV: 38-59), 3-methylthiopropionaldehyde (OAV: 47-96), ethyl caprylate (OAV: 30-38), while nonanal, phenyl acetaldehyde and vanillin contributed significantly to the Huangjiu fermented with japonica rice. The multivariate statistical analysis further confirmed that 17 compounds (VIP > 1 and p < 0.05) could be supposed to be the key compouns that cause significant flavor differences in Huangjiu samples fermented with different brewing rice. Moreover, partial least-squares analysis revealed that most compounds (ethyl butyrate, 3-penten-2-one, isoamyl acetate, and so on) correlated with ester and alcoholic aroma. The results could provide basic data and theoretical basis for the selection of raw materials in Huangjiu.

Identification and quality evaluation of Chinese rice wine using UPLC-PDA-QTOF/MS with dual-column separation

BACKGROUND

Chinese rice wine (CRW) is a well-known drink and functional food that is used in traditional Chinese medicine. However, there is still a lack of quality control and evaluation methods for CRWs.

PURPOSE

The study aimed to establish a new method that can serve both as quality control and evaluation method and, as well as an identification method for CRWs.

METHOD

Compound identification in different CRW samples and determination of uracil, xanthine, uridine, adenine, guanosine, 5-hydroxymethylfurfural, and adenosine contents from 29 CRW samples from 14 brands were performed using UPLC-PDA/TOF-MS. The dual-column chromatographic separation of CRW was performed using CORTECS T3 coupled to HSS T3. The optimal mobile phase consisted of water with 0.1% formic acid, 40 mM ammonium acetate, and methanol: acetonitrile (2:1). Furthermore, to compare the UPLC fingerprints between CRWs of different brands, a similarity analysis was performed to classify the CRW samples. Finally, network pharmacology and in vitro efficacy and toxicity tests were used to investigate the biological function of the seven components and CRWs.

RESULTS

A total of 55 compounds were unambiguously or tentatively identified. Among them, nucleoside, pyrimidines and purines were reported in CRW for the first time. The seven components were successfully determined, and their contents showed large variations among different brands of CRW, which was consistent with the results of the chromatographic fingerprint similarities. The results of in vitro efficacy and toxicity tests indicated that CRWs and seven components had obvious protective effect on H9c2 cell injury induced by the H₂O₂ model. Network pharmacology analysis showed that these seven compounds might be the main active components of CRW that promote blood circulation and ventilation.

CONCLUSION

This study revealed that dual-column chromatographic separation is an effective method for quantitative and chromatographic fingerprint analyzes of complex samples, and seven compounds can be used for the quality evaluation and control of CRWs.

The formation of higher alcohols in rice wine fermentation using different rice cultivars

Higher alcohols are closely related to the flavor and safety of rice wine. The formation of n-propanol, isobutanol, isoamyl alcohol, and phenylethanol during rice wine fermentations was for the first time investigated in this study among 10 rice cultivars from two main production regions. Rice wine made from Yashui rice, the long-grain non-glutinous rice from Guizhou, produced the highest yields of higher alcohols (487.45 mg/L), and rice wine made from five glutinous rice cultivars produced the lowest yields of higher alcohols (327.45-344.16 mg/L). An extremely strong correlation was found between the starch in rice and higher alcohols in rice wine. Further analysis first showed that the former fermentation period was key for the nutrient consumption and higher alcohol formation, with more than 55% of glucose being consumed and more than 75% of higher alcohols being synthesized in 48 h. Correlation analysis confirmed the strong correlation between nutrient consumption and higher alcohol formation including valine-isobutanol (coefficient higher than 0.8 in seven rice cultivars and higher than 0.6 in three rice cultivars), glucose-isoamyl alcohol (coefficient higher than 0.8 in five rice cultivars and higher than 0.6 in the other five rice cultivars), and glucose-phenylethanol (coefficient higher than 0.8). The correlation of threonine-n-propanol, leucine-isoamyl alcohol, phenylalanine-phenylethanol, glucose-n-propanol, and glucose-isobutanol varied among the rice wines made from 10 rice cultivars. RT-qPCR analysis on five target genes verified the variation caused by different rice cultivars. this study for the first time reported the special formation pattern of higher alcohols during rice wine fermentation, emphasizing the early contribution of glucose metabolism on the formation of isobutanol. This study highlighted the significance of rice selection for making rice wine with good quality and provided theoretical references for the control of higher alcohols, especially in the former period of rice wine fermentation.

Flavor compounds with high odor activity values (OAV > 1) dominate the aroma of aged Chinese rice wine (Huangjiu) by molecular association

Aging is an essential operation to perfect the flavor quality of Hungjiu. In this study, formation mechanism of flavor compounds responsible for the characteristic flavor of aged Huangjiu was investigated. The contents of umami and bitter free amino acids (FAA) increased with the storage period prolonged, while that of sweet FAA showed downward trend. Gas chromatograph-mass spectrometry and principal component analysis indicated that the volatile flavor compounds with OAV exceed 1, especially middle-chain fatty-acid-ethyl-esters and aromatic compounds, dominated the characteristic flavor of aged Huangjiu. Low field-NMR was firstly applied to characterize the molecular association between water and dissolved flavor compounds in aged Huangjiu. The results showed that basic amino acids contributed greatly to the flavor formation of aged Huangjiu via molecular association. In addition, the molecular association significantly promoted the accumulation of flavor compounds with OAV > 1, especially ethyl esters.

The way of Qu-making significantly affected the volatile flavor compounds in Huangjiu (Chinese rice wine) during different brewing stages

The volatile flavor compounds of Huangjiu (Chinese rice wine) brewed from different raw materials were obviously different, but there were few studies on the volatile flavor compounds of Huangjiu brewed from different wheat Qu at different brewing stages. In this paper, headspace-solid phase microextraction combined with gas chromatography-mass spectrometry, combined with principal component analysis and sensory evaluation, was used to determine the volatile flavor compounds in Huangjiu brewed from wheat Qu made by hand and wheat Qu made by mechanical. The results showed that there were significant differences in the contents and types of volatile flavor substances in Huangjiu brewed from different wheat Qu at fermentation stages, and the prefermentation and postfermentation Huangjiu samples could be well distinguished from each other. Compared with the Huangjiu brewed from wheat Qu made by mechanical, the Huangjiu brewed from wheat Qu made by hand has stronger aroma and better taste.

Potential Use of Emerging Technologies for Preservation of Rice Wine and Their Effects on Quality: Updated Review

Rice wine, a critical fermented alcoholic beverage, has a considerable role in different cultures. It contains compounds that may have functional and nutritional health benefits. Bacteria, yeasts, and fungi commonly found in rice wines during fermentation can induce microbial spoilage and deterioration of the quality during its distribution and aging processes. It is possible to control the microbial population of rice wines using different preservation techniques that can ultimately improve their commercial shelf life. This paper reviews the potential techniques that can be used to preserve the microbial safety of rice wines while maintaining their quality attributes and further highlights the advantages and disadvantages of each technique.

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.

Changes in Flavor- and Aroma-Related Fermentation Metabolites and Antioxidant Activity of Glutinous Rice Wine Supplemented with Chinese Chestnut (Castanea mollissima Blume)

Traditional glutinous rice wine (TGRW) has been fermented in China for over 9000 years. Recently, an innovative regional variation of TGRW, chestnut rice wine, banli mijiu (BLMJ), was developed by adding Chinese chestnut (Castanea mollissima Blume) into the fermentation brew. The objective of this study was to characterize the effects of chestnut on the nutritional, aromatic, and antioxidant properties of TGRW. To compare the aromatic sensory profiles between TGRW and BLMJ, the free amino acids and ethyl carbamate, phenolic, and flavonoid contents were determined. In addition, the antioxidant properties, including reducing power, metal chelation, and free radical scavenging activities, were also compared. A total of 98 distinct flavor components were identified in BLMJ, among which 38 were detected by sniffing instrument, compared to 77 distinct flavor components in TGRW. BLMJ thus contains a wider range of flavor components, but similar alcohol, acid and reducing sugar profiles compared with TGRW. Twenty-five free amino acids were detected in both wines, with lower contents of each in BLMJ compared with TGRW. BLMJ also exhibited stronger antioxidant properties than TGRW. The findings of this study suggest that chestnut can increase the diversity of aromatic components and improve antioxidant qualities of traditional rice wine.

Flavor profile variations of Huangjiu brewed in different traditional Chinese solar terms

Background

Through long-term research on Huangjiu fermentation, it has been found that the quality of Huangjiu closely associated with Chinese 24-solar term through long-term investigations. Therefore, this study was conducted to explore the characteristic and property indexes differences of Huangjiu—like aroma and flavor profile, and physicochemical properties—brewed in different solar terms by choosing five representative fermentation times of Shaoxing Huangjiu.

Results

Huangjiu samples in current study all meet the national standards of traditional semi-dry Huangjiu. There are significant differences of physicochemical properties like acidity and amino nitrogen among different solar-term groups. Forty-three detected volatiles were applied by PCA and PLS-DA analyses to differentiate main factors. Volatiles mainly loaded to four PCs, which accounted for 86.5%. Nineteen volatiles were discriminated to significantly differentiate solar-term groups. OAV analysis found 14 compounds with OAV &gt; 1, while correlation analysis between volatiles and the outcomes of sensory evaluation displayed the various properties of Huangjiu on aroma and flavor due to the various combination of volatiles, reducing sugar, acidity and amino nitrogen. After national wine inspector evaluated and scored Huangjiu fermented in different solar terms, Huangjiu brewed in Winter Solstice exhibited the highest performance, whose score is 91.0, and praised as the gold medal product.

Conclusion

The methodology of this study can help to produce more types of adorable flavor and aroma of alcoholic beverages to consumers, build varietal Huangjiu or other alcoholic beverages through fermenting guidance by solar term, and even expand the applications of traditional Chinese 24-solar term.

The Correlation Mechanism between Dominant Bacteria and Primary Metabolites during Fermentation of Red Sour Soup

Chinese red sour soup is a traditional fermented product famous in the southwestern part of China owing to its distinguished sour and spicy flavor. In the present study, the effect of inoculation of lactic acid bacteria (LAB) on the microbial communities and metabolite contents of the Chinese red sour soup was investigated. Traditional red sour soup was made with tomato and red chilli pepper and a live count (108 CFU/mL) of five bacterial strains (including Clostridium intestinalis: Lacticaseibacillus rhamnosus: Lactiplantibacillus plantarum: Lacticaseibacillus casei: Lactobacillus paracei) was added and fermented for 30 days in an incubator at 37 °C. Three replicates were randomly taken at 0 d, 5 d, 10 d, 15 d, 20 d, 25 d and 30 d of fermentation, with a total of 21 sour soup samples. Metabolomic analysis and 16S-rDNA amplicon sequencing of soup samples were performed to determine microbial diversity and metabolite contents. Results revealed that fermentation resulted in the depletion of native bacterial strains as LAB dominated over other microbes, resulting in differences in the relative abundance of bacteria, and types or contents of metabolites. A decrease (p < 0.01) in Shannon and Simpson indices was observed at different fermentation times. The metabolomic analyses revealed a significant increase in the relative content of 10 metabolites (particularly lactic acid, thymine, and ascorbic acid) in fermented samples as compared to the control. The correlation network revealed a positive association of Lacticaseibacillus rhamnosus with differentially enriched metabolites including lactic acid, ascorbic acid, and chlorogenic acid, which can desirably contribute to the flavor and quality of the red sour soup.

The sensory and flavor characteristics of Shaoxing Huangjiu (Chinese rice wine) were significantly influenced by micro-oxygen and electric field

In order to improve the high cost of equipment and difficult management caused by the natural aging of Chinese rice wine (Huangjiu), micro-oxygen (MO) and electric field (PEF) technology are used to accelerate the aging of Huangjiu. The results showed that micro-oxygen and electric field have a significant effect on the sensory characteristics and flavor characteristics of Huangjiu. Compared with the naturally aged Huangjiu, the flavor compounds of Huangjiu treated with micro-oxygen and electric field increase significantly. Based on principal component analysis, Huangjiu processed at 0.35 mg L/day or 0.5 mg L/day combined electric field exhibited similar flavor to the natural aged Huangjiu, which was highly associated with long-chain fatty acid ethyl esters (C13-C18). Moreover, partial least squares regression demonstrated that sensory attributes of cereal aroma and astringency were highlighted after aging time, while fruit aroma, continuation, and full body were dominant after micro-oxygen and electric field treatment. Micro-oxygen and electric field effectively enhanced the quality of Huangjiu, which could be applied in other alcoholic beverages.

Comparison of the Fermentation Activities and Volatile Flavor Profiles of Chinese Rice Wine Fermented Using an Artificial Starter, a Traditional JIUYAO and a Commercial Starter

In this study, an artificial starter culture was prepared using the core microbial species of JIUYAO to produce Chinese rice wine (CRW). The fermentation activity and flavor profiles of CRW samples fermented with traditional JIUYAO, a commercial starter culture, and our artificial starter culture were compared. The optimal protectant combination for lyophilization of the artificial starter was established as 15.09% skim milk, 4.45% polyethylene glycol, 1.96% sodium glutamate, and 11.81% maltodextrin. A comparative analysis revealed that the ethanol content of the three CRW samples was similar. The total acid content of the CRW sample fermented with the artificial starter (7.10 g/L) was close to that of the sample fermented with JIUYAO (7.35 g/L), but higher than that of the sample fermented with the commercial starter (5.40 g/L). An electronic nose analysis revealed that the olfactory fingerprints of the CRW samples fermented with JIUYAO and the artificial starter resembled each other. For both above mentioned samples, the flavor profiles determined by gas chromatography–mass spectrometry indicated some differences in the variety and content of the aroma compounds, but the key odorants (odor activity values ≥1), such as isoamyl acetate, ethyl acetate, phenyl alcohol, and isoamyl alcohol, were similar.

Characterization of the key aroma compounds of a sweet rice alcoholic beverage fermented with Saccharomycopsis fibuligera

This study aims to examine the effect of the non-Saccharomyces yeast Saccharomycopsis fibuligera on the sensory quality and flavour characteristics of a sweet rice alcoholic beverage. The strain S. fibuligera was isolated from a traditional Chinese hand-made starter with the purpose to improving sweet rice wine fragrance. Here, sweet rice wines were produced by six combinations of three species of fermentation strains, including S. fibuligera, Rhizopus and Saccharomyces cerevisiae, for evaluation. The study results showed significant diversities within these rice wines based on indicators including the score of quantitative descriptive analysis and volatile variety and content as well as odour activity value (OAV). Quantitative results showed that 43 volatile compounds were identified by headspace-solid phase microextraction with gas chromatography-mass spectrometry among samples. Based on the principal component analysis and OAV calculation, the two samples (S-2 and S-3) fermented with S. fibuligera and Rhizopus possessed high scores and were distinguished from the others, and ethyl butanoate, ethyl hexanoate, β-phenylethyl alcohol and 1-octen-3-one with high OAVs were responsible for the key aroma of sweet rice wine fermented with S. fibuligera. Co-inoculating S. fibuligera, Rhizopus or/and S. cerevisiae generated more pleasant aroma compounds in a sweet rice alcoholic beverage than when inoculated individually.

Regulatory Mechanisms of L-Lactic Acid and Taste Substances in Chinese Acid Rice Soup (Rice-Acid) Fermented With a Lacticaseibacillus paracasei and Kluyveromyces marxianus

Rice-acid has abundant taste substances and health protection function due to the various bioactive compounds it contains, including organic acids. L-lactic acid is the most abundant organic acid in rice-acid, but the regulatory mechanisms of L-lactic acid accumulation in rice-acid are obscure. In this study, we analyzed the dynamic changes in organic acids and taste substances in rice-acid in various fermentation phases and different inoculation methods. We identified the key genes involved in taste substance biosynthesis by RNA-Seq analysis and compared the data of four experimental groups. We found that the interaction of the differences in key functional genes (L-lactate dehydrogenase and D-lactate dehydrogenase) and key metabolism pathways (glycolysis, pyruvate metabolism, TCA cycle, amino acid biosynthesis, and metabolism) might interpret the accumulation of L-lactic acid, other organic acids, and taste substances in rice-acid fermented with Lacticaseibacillus paracasei. The experimental data provided the basis for exploring regulatory mechanisms of taste substance accumulation in rice-acid.

Peptides in Brewed Wines: Formation, Structure, and Function

The traditional low-alcoholic beverages, such as grape wine, sake, and rice wine, have been consumed all over the world for thousands of years, each with their unique methods of production that have been practiced for centuries. Moderate consumption of wine is generally touted as beneficial for health, although there is ongoing debate for the responsible components in wine. In this review, the structural and functional characteristics, the formation mechanisms, and their health-promoting activities of peptides in three brewed wines, grape wine, Chinese rice wine (also called Chinese Huangjiu or Chinese yellow wine), and Japanese sake, are discussed. The formation of peptides in wine imparts sensorial, technological, and biological attributes. Prospects on future research, with an emphasis on the peptide characterization, formation mechanism, physiological activity, and molecular mechanisms of action, are presented.

Effects of vacuum soaking on the hydration, steaming, and physiochemical properties of japonica rice

Soaking is an essential step in the processing of various rice products. In this study, the influences of vacuum soaking on hydration, steaming, and physiochemical properties of rice were investigated. Results showed that vacuum soaking accelerated water absorption as well as affected the mobility and density of water protons inside rice during soaking. Vacuum soaking could considerably shorten the optimal steaming time from 58 to 32 min and reduce the adhesiveness of steamed rice. Microstructure analysis of rice revealed that porous structure was formed on rice surface and the arrangement of starch granules became loosened after vacuum soaking. Moreover, vacuum soaking slightly reduced the relative crystallinity of rice starches without altering the crystalline type. The gelatinization temperature as well as the peak and trough viscosity was also decreased after vacuum soaking. Our study suggested that vacuum soaking was conducive to improve the soaking and steaming properties of rice.

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

BACKGROUND

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.

RESULTS

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.

CONCLUSION

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.

Identification of colloidal haze protein in Chinese rice wine (Shaoxing Huangjiu) mainly by matrix-assisted laser ionization time-of-flight mass spectrometry

As one of the three most famous brewed wines in the world, Chinese rice wine is made from rice and husked millet, containing 14 percent to 20 percent alcohol. Highly original, yellow wine brewing techniques are regarded as the model of the wine brewing industry in Asia. Shaoxing Huangjiu is produced in Zhejiang province and remains the oldest and most representative Chinese rice wine. During storage, Shaoxing Huangjiu is susceptible to environmental disturbance and produces colloidal haze to result in turbidity. In this study, the main composition and source of colloidal haze protein in Shaoxing Huangjiu were analyzed by two-dimensional electrophoresis and matrix-assisted laser ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS). The results showed that the proteins in colloidal haze mainly consisted of oat protein b1, oat-like protein, di-amylase inhibitor, pathogenesis-related protein, pathogenesis-related protein-4, chitinase II derived from wheat and oat-like protein, and beta-amylase derived from rice. The amino acid composition and secondary structure of haze protein and supernatant protein in Huangjiu were further explored by high-performance liquid chromatography and Fourier transform infrared spectroscopy. The study has broadened knowledge of the main composition and source of colloidal haze protein in Shaoxing Huangjiu. The corresponding results indicated that the amino acid composition from colloidal haze had the main characteristics of high hydrophobicity and low water solubility.

Effects of glutinous rice protein components on the volatile substances and sensory properties of Chinese rice wine

The content of protein components of glutinous rice significantly affects the quality of Chinese rice wine. Therefore, the effects of protein components on the quality of Chinese rice wine were investigated by adding the exogenous proteins glutelin and albumin individually or in combination RESULTS: Compared with the control, the samples with increased glutelin components exhibited improved formation of numerous alcohol esters with alcoholic and fruity representatives. The promotion rates of glutelin to total alcohols and total esters were 18% and 99%, respectively. The amount of 4-vinylguaiacol characterized by a spicy, smoky odor was reduced to 40%. Correlation analysis between chemical composition and sensory characteristics showed a significant positive correlation between umami and amino nitrogen (r = 0.935) and total amino acid content (r = 0.729). The bitterness of Chinese rice wine was related to the change of alcohol content (r = 0.689) and total soluble solid (r = 0.904). Sensory analysis revealed that the increase of the glutelin component of Chinese rice wine increased its alcoholic, fruity, and honey-like features, as well as its umami, acidity and bitterness. The increase also reduced the caramel-like, herb-like, and smoky sensory characteristics of Chinese rice wine and its Qu aroma and sweetness CONCLUSION: The protein content of glutinous rice significantly affects the quality of rice wine. The Glutelin has a significant relationship with fruity, honey, and umami flavors; the albumin has a significant relationship with medicinal, bitter, and astringent flavors. Therefore, reasonable adjustment of the glutelin content of glutinous rice can effectively improve the sensory quality of rice wine. © 2020 Society of Chemical Industry.

Metagenomic analysis reveals the impact of JIUYAO microbial diversity on fermentation and the volatile profile of Shaoxing-jiu

This study focused on the microbial communities found in JIUYAO, the fermentation starter traditionally used in Shaoxing-jiu, and elucidated their relationship with the fermentation activities and volatile compounds involved in winemaking. The microbial communities found in all JIUYAO samples tested were dominated by Pediococcus and Weissella bacteria and Saccharomycopsis and Rhizopus fungi. Saccharifying power showed significant positive correlations with the presence of Pedioccoccus, Saccharomycopsis, and Rhizopus, whereas acid production capacity was strongly associated with Pedioccoccus, Weissella, and Rhizopus. Alcohol production capacity positively correlated with the presence of Pedioccoccus and Rhizopus. Fifteen important volatile compounds (odor-activity values ≥ 1) including esters, alcohols, acids, and aldehydes were identified in Huangjiu samples fermented with JIUYAO. Positive correlations were found between Saccharomycopsis and phenylethanol/ethyl butyrate, Rhizopus and ethyl propionate/ethyl laurate/ethyl butyrate, Pedioccoccus and ethyl laurate/acetic acid, and Weissella and decanoic acid/isopentanol. These results imply that these microorganisms significantly contribute to the fermentation activities and flavor of Shaoxing-jiu. Finally, the results showed that a combination of five core microbes with Saccharomyces cerevisiae could be used as a starter in winemaking. To conclude, this study provides a comprehensive overview of the core microbes found in JIUYAO and strategies for the selection of beneficial microorganisms to improve the quality and flavor of Shaoxing-jiu.

Bioprocessed Production of Resveratrol-Enriched Rice Wine: Simultaneous Rice Wine Fermentation, Extraction, and Transformation of Piceid to Resveratrol from Polygonum cuspidatum Roots

A new bioprocess to produce resveratrol-enriched rice wine was established and the effects of adding Polygonum cuspidatum root powder to rice wine fermentation were investigated. In this new process, piceid and resveratrol were extracted from P. cuspidatum roots to rice wine and piceid was converted to resveratrol by β-glucosidase during fermentation. After 10 days co-fermentation, rice wine with high levels of resveratrol was obtained, which contained ~14% (v/v) ethanol, 122 mg/L piceid, and 86 mg/L resveratrol. The resveratrol-enriched rice wine had enhanced antioxidant activity with significantly stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, ferric ion reducing power, and ferrous ion chelating capability. Ultrafiltration (UF) was employed in this study using hollow fibers to clarify the end product, increase shelf life without heat treatment, and maintain the quality of the phenolic compounds. The boiled and UF-treated rice wine were evaluated for ethanol, piceid, resveratrol, clarity, aerobic plate count, total acidity, pH, reducing sugars, and amino acids. The quality of the resveratrol-enriched rice wine was maintained after four weeks storage at normal refrigeration temperatures.

The quality of rice wine influenced by the crystal structure of rice starch

Normal rice wine (NRW) and waxy rice wine (WRW) were fermented to study the relationship between the structure of starch as well as the taste and texture of rice wine. The total starch content of NRW decreased to 21.2%, and that of WRW decreased to 15.6%. The water-soluble sugar content of NRW increased to 169.3, and that of WRW increased to 194.4 mg/g. The ethanol content of NRW increased to 6.5%, and that of WRW increased to 8.9%. These changes indicated that WRW exhibited higher quality than NRW. Sweetness was negatively correlated with total starch content and positively correlated with ethanol content. Starch molecules were degraded by enzymolysis, thereby enhancing crystallinity. The size of starch particle was negatively correlated with crystallinity, whereas the chewiness and gumminess of vinasse (fermented rice grains) were positively correlated with the size of starch particle and negatively correlated with crystallinity. The higher degrees of chewiness and gumminess of vinasse render the texture of WRW superior to that of NRW. The results indicated that WRW is superior to NRW in taste and texture because of the difference in starch structure.