Fermented Alcoholic Beverages Research Articles

Oak Leaves as a Raw Material for the Production of Alcoholic Fermented Beverages

This study aimed to point out the possible use of oak leaves (Q. petraea) in the production of fermented alcoholic beverages. Parameters such as antioxidant capacity, total phenolic content, phenolics and sugars were determined using spectrophotometric and chromatographic methods. pH values were also determined, and in the final product with a fermentation length of 85 days, the alcohol content was determined and sensory analysis performed. The antioxidant capacity of the beverage was lower compared to the infusions before fermentation, and its highest values were recorded in the leaf samples, in which the highest values of phenolic compounds and the total phenolic content were also recorded. A decrease in the content of total phenolics was recorded with the increasing length of fermentation in beverage samples. However, the fermentation process had a positive effect on the contents of some phenolic substances such as catechin, gallic acid and gallocatechin. Sensory analysis showed a higher acceptability of the fermented beverage without the addition of orange, which could be caused by the higher sugar content in these samples. Oak leaves therefore represent a suitable raw material for the production of a fermented alcoholic beverage, without the need to enrich the taste with other ingredients.

Development of a defined mixed starter culture for the improvement of Tej, Ethiopian honey wine.

Ethiopian honey wine, Tej, is the most popular traditionally fermented alcoholic beverage in Ethiopia. Owing to the spontaneous fermentation process, the final product is neither predictable nor consistent in quality. Attempts have not been made before to solve this problem. Thus, the aim of this study was to develop a potential mixed starter culture of yeast and lactic acid bacteria isolated from Tej samples for the production of Tej with consistent quality. One hundred seventy-seven lactic acid bacteria and 194 yeasts were isolated from 30 Tej samples collected from southwest Ethiopia. After sequentially testing the isolates towards physiological stress tolerance and desired metabolic products, 10 lactic acid bacteria and 10 yeast isolates were screened. Later, four lactic acid bacteria and four yeast isolates were found to be compatible in co-culture tests. Finally, the combination of lactic acid bacteria and yeast isolates was formulated using the design of expert version 7.0.0 software, and six formulates (F #1-6) were designed. Controlled Tej fermentation was performed under laboratory conditions using six lactic acid bacteria-yeast starter culture formulations. The sensory attributes, in terms of color, flavor, odor, turbidity, and overall acceptance analysis scored 4.8/5.0 (F #2) and 4.7/5.0 (F #6), with mean significant variations (p < 0.05) among the other formulates. These two formulates were considered the best-mixed starter cultures compared to the control and other formulates. Matrix-assisted laser desorption ionization-time of flight analysis revealed that the lactic acid bacteria starters (AAUL7 and AAUL10) belonged to Lactobacillus paracasei. While the yeast starters (AAUY2 and AAUY8) belonged to Saccharomyces cerevisiae. These mixed lactic acid bacteria-yeast starter cultures could be used as the best starter culture for the fermentation of Ethiopian honey wine, Tej, with consistent quality.

Advancements in Fermented Beverage Safety: Isolation and Application of Clavispora lusitaniae Cl-p for Ethyl Carbamate Degradation and Enhanced Flavor Profile.

Ethyl carbamate (EC) is a natural by-product in the production of fermented food and alcoholic beverages and is carcinogenic and genotoxic, posing a significant food safety concern. In this study, Clavispora lusitaniae Cl-p with a strong EC degradation ability was isolated from Daqu rich in microorganisms by using EC as the sole nitrogen source. When 2.5 g/L of EC was added to the fermentation medium, the strain decomposed 47.69% of ethyl carbamate after five days of fermentation. It was unexpectedly found that the strain had the ability to produce aroma and ester, and the esterification power reached 30.78 mg/(g·100 h). When the strain was added to rice wine fermentation, compared with the control group, the EC content decreased by 41.82%, and flavor substances such as ethyl acetate and β-phenylethanol were added. The EC degradation rate of the immobilized crude enzyme in the finished yellow rice wine reached 31.01%, and the flavor substances of yellow rice wine were not affected. The strain is expected to be used in the fermented food industry to reduce EC residue and improve the safety of fermented food.

Conjugated molecularly imprinted polymers based on covalent organic frameworks: Fluorescent sensing platform for specific capture of urea and elimination of ethyl carbamate

This study described the preparation of an azide covalent organic framework-embedded molecularly imprinted polymers (COFs(azide)@MIPs) platform for urea adsorption and indirect ethyl carbamate (EC) removal from Chinese yellow rice wine (Huangjiu). By modifying the pore surface of COFs using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, COFs(azide) with a high fluorescence quantum yield and particular recognition ability were inventively produced. In order to selectively trap urea, the COFs(azide) were encased in an imprinted shell layer via imprinting technology. With a detection limit (LOD) of 0.016 μg L-1 (R2 = 0.9874), the COFs(azides)@MIPs demonstrated a good linear relationship with urea in the linear range of 0–5 μg L-1. Using real Huangjiu samples, the spiking recovery trials showed the viability of this sensing platform with recoveries ranging from 88.44 % to 109.26 % and an RSD of less than 3.40 %. The Huangjiu processing model system achieved 38.93 % EC reduction by COFs(azides)@MIPs. This research will open up new avenues for the treatment of health problems associated with fermented alcoholic beverages, particularly Huangjiu, while also capturing and removing hazards coming from food.

Diversity of Production Techniques and Microbiology of African Cereal-Based Traditional Fermented Beverages

Traditional fermented beverages are culturally and socially accepted products for consumption, drinking, entertainment, customary practices, and for religious purposes. The purpose of this review was to identify some cereal-based fermented beverages and determine the differences in their production technologies. There are many unique regional variations in the preparation of each of the identified fermented beverages. They are prepared from raw materials such as maize, millet, rice, and sorghum. Majority of the fermented alcoholic beverages (binuburan, amba beer, sake, dolo, pito, and tchoukoutou) were produced using spontaneous fermentation and industrial fermentation (use of starter cultures) techniques. The various microbial communities associated with the traditional fermentation processes were dominated by Limosilactobacillus fermentum and Lactiplantibacillus plantarum for Lactic acid bacterial (LAB) species, Saccharomyces cerevisiae and Candida mycoderma for Saccharomyces and Candida species (yeasts), respectively; and Aspergillus aceti and Rhizopus stolonifer for Aspergillus and Rhizopus species (molds), respectively. Acetobacter, Pseudomonas, Klebsiella, Weissella, Achromobacter, Flavobacterium, Micrococcus, and Bacillus dominated other microbial genera. The involvement of lactic acid bacteria contributed to the safety and extension of the shelf life of the final products. Most of these beverages were found to be very rich in proteins, carbohydrates, calories, and B-group vitamins including thiamine, folic acid, riboflavin, and nicotinic acid. This article reviewed the available information, such as processing techniques of African traditional beverages, the raw materials used to producing them, and the microorganisms associated with the production processes.

Multi-Omics Analysis of the Co-Regulation of Wood Alcohol Accumulation in Baijiu Fermentation

Methanol, also known as wood alcohol, is a common hazardous by-product of alcoholic beverage fermentation and serves as a crucial indicator for assessing the safety of alcoholic beverages. However, the metabolic mechanisms of methanol production during the solid-state fermentation of Chinese Baijiu remain unclear. In this study, we sought to determine the primary stage of methanol production in Chinese Baijiu by measuring the methanol content at different stages of fermentation. High-throughput multi-omics sequencing techniques were employed to elucidate methanol metabolic pathways and associated microorganisms. In addition, a comprehensive analysis incorporating environmental factors and microbial interactions was conducted to explore their combined effects on methanol production. Methanol was predominantly produced during pit fermentation, with the most significant increase observed within the first seven days. Microorganisms such as Pichia kudriavzevii, Byssochlamys spectabilis, Penicillium, and Aspergillus played a regulatory role in methanol content during the first seven days through their involvement in butyrate and methane metabolic pathways and pectin degradation modules. During Baijiu production, various types of molds and yeasts participate in methanol production. Differences in their abundance within fermentation cycles may contribute to variations in methanol content between stages. Lactobacillus accumulated abundantly in the first seven days in each stage, suppressing methanol-metabolizing microorganisms. In addition, the increased acidity resulting from Lactobacillus metabolism may indirectly promote methanol generation.

Dietary exposure to aflatoxin B1 and ethanol from homemade and industrial fermented beverages in South Kivu, Democratic Republic of the Congo

BACKGROUND: The prevalence of AFB1 contamination in agricultural products used to produce fermented alcoholic beverages is increasing, raising concerns for human health. AIM: The aim of this study was to investigate dietary exposure to AFB1 and ethanol through homemade and industrial fermented beverages commonly consumed in South Kivu, DR Congo. METHOD: AFB1 and ethanol were measured using reverse-phase HPLC with a fluorescence detector and a refractive index detector, respectively. Data on fermented beverage consumption were collected from 847 adults using a food frequency questionnaire (FFQ). RESULTS: The findings revealed that industrial sample Man 8 had the highest exposure to AFB1 (77.8 ± 45.0 ng/kg b.w/day) and Man4 had the highest ethanol exposure (4.83 ± 2.40 mg/kg b.w/day); while among homemade samples, Kasiksi had the highest exposure to both AFB1 (8.8 ± 6.6 ng/kg b.w/day) and ethanol (2.46 ± 1.85 mg/kg b.w/day). The margin of exposure (MOE) for AFB1 was 1011.7 or less, and for ethanol, it was 818.2 or less. Men are more likely to be exposed. CONCLUSION: Increased consumption of homemade and industrial fermented beverages raises the risk of developing hepatocellular cancer (HCC) because the levels of AFB1 and ethanol MOE drop below the safe limit of 10000. Further research is needed to investigate the connection between AFB1, ethanol, and HCC, especially in regions where alcohol misuse is common.

Persimmon tannin promotes the growth of Saccharomyces cerevisiae under ethanol stress.

Saccharomyces cerevisiae plays a pivotal role in various industrial processes, including bioethanol production and alcoholic beverage fermentation. However, during these fermentations, yeasts are subjected to various environmental stresses, such as ethanol stress, which hinder cell growth and ethanol production. Genetic manipulations and the addition of natural ingredients rich in antioxidants to the culture have been shown to overcome this. Here, we investigated the potential of persimmon tannins, known for their antioxidative properties, to enhance the ethanol stress tolerance of yeast. Assessment of the effects of 6.25 mg mL-1 persimmon tannins after 48 h incubation revealed cell viability to be increased by 8.9- and 6.5-fold compared to the control treatment with and without 12.5% ethanol, respectively. Furthermore, persimmon tannins reduced ethanol-induced oxidative stress, including the production of cellular reactive oxygen species and acceleration of lipid peroxidation. However, persimmon tannins could hardly overcome ethanol-induced cell membrane damage. The findings herein indicate the potential of persimmon tannin as a protective agent for increasing yeast tolerance to ethanol stress by restricting oxidative damage but not membrane damage. Overall, this study unveils the implications of persimmon tannins for industries relying on yeast. © 2024 Society of Chemical Industry.

A review of the production, quality, and safety of traditionally fermented cereal-based alcoholic beverages in Ethiopia.

In Ethiopia, a diverse array of cereal-based alcoholic beverages is being prepared andconsumed. These traditional fermented drinks are distinct to specific regions and are prepared by locals using locally available raw materials according to cultural traditions. Notable among these are Tella, Areki, Keribo, Borde, and Shamita, renowned for their nutritional benefits and their role in ensuring food security. This paper explores existing literature regarding the production, quality, and safety of traditional cereal-based alcoholic beverages in Ethiopia. Despite the widespread consumption of these beverages, they have yet to be commercialized, mainly due to their perceived low quality. The uncommercialized processes and products demand more attention, particularly in light of the country's inflationary pressures. Additionally, these traditional fermented beverages significantly enhance health due to the presence of bioactive compounds and their nutritional value. Standardizing and modernizing production methods by integrating scientific knowledge, such as optimizing fermentation practices, is essential to fully capitalize on these traditional beverages. Equipping local producers with this knowledge can facilitate the transition to larger scale production. Furthermore, continued research is essential to maintaining overall quality and safety standards. Therefore, it is crucial to concentrate on enhancing the nutritional value and quality of traditional cereal-based beverages in the future. By illuminating these aspects, this review aims to enhance understanding of the traditional Ethiopian alcoholic beverage industry and its potential for elevating quality and safety standards. Moreover, the review explores these beverages' cultural significance, consumption patterns, and associated health risks.

Rice-Based Alcoholic Fermented Beverages of North-East India: Insight into Ethnic Preparation, Microbial Intervention, Ethnobotany, and Health Benefits

Introduction. Alcoholic fermented rice-based beverages (AFRBs) have been used since time immemorial for spiritual connection and cultural rituals in North-East India. AFRBs are also used traditionally in the healthcare system for remedy of tiredness, digestion problems, hypertension, and diabetes. Problems Statement. Limited scientific documents are available on AFRBs including starter cake preparation, production of the beverages, microbial intervention, nutritional aspects, and health benefits. Objectives. This review has been undertaken to find insight into ethnic preparation, microbial intervention, ethnobotany, and health benefits as well as nutritional aspects of popular AFRBs of North-East India. Major Findings. Studies reveal that AFRBs are enriched with medicinal benefits due to the presence of various microflora and medicinal plants. The presence of medicinal plants plays an important role underlying the health benefits of AFRBs. In addition, several functional microorganisms, such as strains of Lactobacillus and yeast, enhance the therapeutic potential of the AFRBs. Interestingly, strains of Pediococcus and Lactobacillus spp. improve bile and gastric juice tolerance, hyperlipidemia, diabetes, obesity, and amylolytic activities and regulate the expression of fatty acid biosynthetic genes. Moreover, strains of Saccharomyces decrease the secretion of proinflammatory cytokines and alter the respective mRNA expression. Furthermore, the consumption of AFRBs has no harmful effect among the communities on a regular basis in normal diet. Conclusion. A detailed scientific approach is required to maintain the desired product quality of AFRBs for the upliftment of the socioeconomic status of North-East India.

Case study on the influence of serving temperature on the aroma release and perception of Huangjiu, a fermented alcoholic beverage

Serving temperature plays a crucial role in influencing the sensory experience of consumers. In this context, this study investigated the influence of serving temperature on the aroma release and perception of a typical fermented alcoholic beverage named Huangjiu. A quantitative sensory description analysis was conducted, determining serving temperature significantly influenced the 17 sensory attributes in both semi-dry and semi-sweet Huangjiu. The variation in the contents of 41 volatiles in the Huangjiu with temperature was investigated using gas chromatography-ion mobility spectrometry, resulting in volatile content significantly increasing above 30 ℃. The partial least squares discriminant analysis was conducted to predict the variable importance for the projection (VIP) of volatiles, and 22 volatiles (VIP > 1) were screened. These 22 volatiles were confirmed as key odorants influenced by serving temperature though aroma addition experiments. The findings would provide a reference for the effects of serving temperature on the flavor perception of fermented alcoholic beverages.

Anti-inflammatory, antithrombotic and anti-oxidant bioactives of beer and brewery by-products, as ingredients of bio-functional foods, nutraceuticals, cosmetics, cosmeceuticals and pharmaceuticals with health promoting properties

&lt;abstract&gt; &lt;p&gt;Fermented alcoholic beverages and their by-products, including beer and breweries' bio-wastes like spent yeasts, grain, and hops, contain a plethora of natural bioactive compounds that have recently gained attention for their valorization as functional ingredients in several novel foods and nutraceuticals, as well as in drugs and cosmetics applications. Within this article, the natural bio-functional compounds of fermented beer product and breweries' by-products with anti-inflammatory, antithrombotic, and anti-oxidant bioactivities are thoroughly reviewed. The important roles of yeasts involved for such bioactives to be present in the fermented product and in the brewery bio-wastes are also outlined. The health promoting benefits of beer moderate consumption resulting from these bioactives, as part of a balanced diet, against inflammation-related chronic disorders is also discussed, along with the detrimental effects of beer consumption abuse and the potential benefits of alternative non-alcoholic beers. The mechanisms of action and synergism of the natural bioactives present in the fermented beer product and in breweries' by-products, with anti-inflammatory, anti-thrombotic, and antioxidant properties are also presented. Current research and future perspectives on valorizing bioactives of fermented beer and brewery by-products, such as spent yeasts, grain and hops in health-promoting functional foods, supplements, nutraceuticals cosmetics, cosmeceuticals, and pharmaceuticals are also thoroughly evaluated, while the limitations of their use are also discussed.&lt;/p&gt; &lt;/abstract&gt;

Analysis of Methanol Content in Different Varieties of Traditionally Fermented Alcohol Found in Chandannath Municipality of Jumla District, Nepal

Background: Alcohol poisoning associated with traditionally fermented alcoholic beverages have been reported in Nepal with the constituents of these beverages not being quantified usually. In traditionally fermented alcoholic beverages, methanol, due to its cheaper cost and similar physiochemical properties with ethanol, is adulterated most commonly and readily. The objective of the present study was to quantify four different varieties of traditionally fermented alcoholic beverages available in Chandannath, Jumla for methanol level.Methods: The present study is a cross-sectional study in which four different types of traditionally fermented alcoholic beverages were collected from Chandannath, Jumla and they were analyzed for methanol content. From Chandannath municipality, the ward number two was selected for collection of samples. Further, from this ward, four different households regularly involved in brewing local alcohol were also randomly selected. These households belonged to three different ethnic groups (Indo-Aryan, Tibeto-Burman and Newar) and these samples were chhyang (sample- 1), local raksi (sample- 2), nigar (sample- 3) and local apple cider (sample- 4). In air tight containers, the samples were sealed and transported to Zest laboratory, Bhaktapur, Nepal for quantification of methanol using Gas Chromatography.Results: The residents in half of these four households belonged to the Tibeto-Burman ethnic groups. Methanol was detected in two samples among the four analyzed beverages. These samples, sample- 2 and sample- 4, on quantification showed the concentrations of 10.050ppm and 13.721ppm of methanol respectively. Conclusion: Among four samples of locally brewed alcoholic beverages, methanol was detected in two samples, but at a concentration below the level that would be considered toxic. This finding emphasizes the importance of conducting larger-scale quantification of traditionally fermented alcohol to mitigate the various health risks associated with its potential toxicity, as these beverages are currently not being quantified.

Preliminary Evaluation of Minor Cereals as Non-Traditional Brewing Raw Materials

Recently, “minor” cereals have been gaining interest due to their distinctive characteristics, not only in terms of nutritional and health potential, but also because of their hardiness. To date, the use of several of these cereals for the production, both at artisan and industrial level, of foods such as pasta and bakery products has already been well established, whereas their investigation for the production of malt and beer has been more limited. In this work, a preliminary analysis of the malting aptitude of einkorn, tritordeum, food-grade sorghum and teff was evaluated. Grain quality parameters that influence the processes of malting and transformation into alcoholic beverages were evaluated, i.e., thousand-kernel weight, test weight, total protein and starch content, falling number, germination capacity, germination energy and amylase activity. Grain analyses showed, on average, satisfactory values for alcoholic fermented beverage production in all the cereal species examined (mainly in tritordeum), whereas the amylase activity of the malts produced was lower than that revealed in barley malt. Fermented drinks derived from these minor cereals, therefore, could be interesting for the light and gluten-free beer markets.

Species identification and strain discrimination of fermentation yeasts Saccharomyces cerevisiae and Saccharomyces uvarum using Raman spectroscopy and convolutional neural networks.

The use of S. cerevisiae and S. uvarum yeast starter cultures is a common practice in the alcoholic beverage fermentation industry. As yeast strains from different or the same species have variable fermentation properties, rapid and reliable typing of yeast strains plays an important role in the final quality of the product. In this study, Raman spectroscopy combined with CNN achieved accurate identification of S. cerevisiae and S. uvarum isolates at both the species and strain levels in a rapid, non-destructive, and easy-to-operate manner. This approach can be utilized to test the identity of commercialized dry yeast products and to monitor the diversity of yeast strains during fermentation. It provides great benefits as a high-throughput screening method for agri-food and the alcoholic beverage fermentation industry. This proposed method has the potential to be a powerful tool to discriminate S. cerevisiae and S. uvarum strains in taxonomic, ecological studies and fermentation applications.

Evaluation of sensory acceptance, purchase intention and color parameters of potentially probiotic mead with Saccharomyces boulardii.

Mead is a fermented alcoholic beverage produced by yeast action on a diluted solution of honey. In this study, for the first time, sensory acceptance, purchase intention and color parameters of potentially probiotic mead with Saccharomyces boulardii were evaluated. The mead with S. boulardii presented yeast counts higher than 106CFU/mL, being considered potentially probiotic, and tended to be yellow in color. About 160 tasters participated in the sensory evaluation, and 69.38% knew mead, but only 35.62% had tried the beverage. In terms of acceptance, the mead were within the acceptable range (above 5), and F2 (with initial soluble solids of 30° Brix and S. boulardii concentration of 0.030g/L) was the most accepted, with an overall average of 7.63 ± 1.42 on the nine-point hedonic scale. In addition, F2 presented the highest purchase intention. In conclusion, the mead showed a tendency towards the color yellow and good sensory acceptance.

A single dietary factor, daily consumption of a fermented beverage, can modulate the gut bacteria and fecal metabolites within the same ethnic community.

Our study investigated how a traditional drink called Apong, made from fermented rice, affects the gut and health of the Mishing community in India. We compared two groups of people who drink Apong to a group of people who do not drink it. To accomplish this, we studied the gut bacteria, fecal metabolites, and blood samples of the participants. It was found that the people who drank Apong had higher blood pressure but lower blood sugar and protein levels than people who did not drink it. We also found that the gut microbiome composition of people who drank Apong was different from those who did not drink it. Moreover, people who drank Apong had lower levels of isovaleric acid in their feces. Overall, this study shows that a traditional drink like Apong can affect the gut bacteria of a community.

A new direct extraction by gas-chromatography with flame ionization detector coupled to head space method for the determination of alcohol content of high matrix wine products

Detection, identification, and quantitation of alcohol in any matrix rich medium is a common practice although sample preparation is inevitable and time consuming. A sensitive, precise and ultimately wide range method for detection, identification and quantification of main content/residual/impurity alcohols without any matrix interference that can be used for production phase quality control, pharmaceutical and/or bio-technological refinement or toxicological evaluation and for forensics is always needed. Even for quality control also for toxicological considerations, ethanol (EtOH) and very similar compound methanol has to be detected and identified definitely becomes vital. However, with the fermented products, the matrix becomes a challenging process, makes the methods inefficient or more extraction methods have to be implanted. Here we propose a new simple and reliable direct extraction method has been developed for the determination of alcohol content of high matrix wine products using the gas-chromatography with flame ionization detector coupled to head space. The method was developed with a rich and complex component mixture of fermented alcoholic beverages (wine) with very high matrix effects. Isopropanol (IPA) was preferred as an internal standard, and Triton X-100 (TX-100) was used as diluting solution in this method. The amount of TX-100, extraction temperature, and the total volume of solution in head space vial (20 mL) were optimized. 2.5% TX-100, 80 °C extraction temperature, and 2.0 ml of total volume were used as optimum condition. Stationary phase was the fused silica, Agilent J&amp;W DB-624 column (30 m x 320 m x 1.8 m) and Helium was used as a mobile phase. GC oven temperature programme was 40C (5 min), 5C/min ramp to 60C (0 min) and 30C/min to 150C (1 min). Performance of the method was assessed by evaluating the recovery, accuracy, precision, linearity, limits of detection (LOD) and limit of quantification (LOQ). Calibration curve was drawn between the concentration of 2.5% to 15.0% EtOH (y = 1.572x – 0.702, R² = 0.9960, y; the ratio of peak area of EtOH to IPA, x: EtOH%). The slopes of standard addition and external calibration curve were statistically same. Recovery of the method was 97.5 ± 3.5 for tree different concentrations and the precision was %5.8 (n= 11). LOD and LOQ were calculated as 0.80% and 2.5%, respectively. The proposed method has a potential for application into the industry and academia with determination of the alcohol content/residual/impurity and also check the quality and content of the fermented medium without the effect of matrix.

Ethyl Carbamate in Fermented Food Products: Sources of Appearance, Hazards and Methods for Reducing Its Content.

Ethyl carbamate, the ethyl ester of carbamic acid, has been identified in fermented foods and alcoholic beverages. Since ethyl carbamate is a probable human carcinogen, reduction of its content is important for food safety and human health. In alcoholic beverages, ethyl carbamate is mostly formed from the reaction of ethanol with urea, citrulline and carbamyl phosphate during fermentation and storage. These precursors are generated from arginine metabolism by wine yeasts and lactic acid bacteria. This review summarizes the mechanisms of ethyl carbamate formation, its impact on human health and methods used in winemaking to minimize its content. These approaches include genetic modification of Saccharomyces cerevisiae wine strains targeting pathways of arginine transport and metabolism, the use of lactic acid bacteria to consume arginine, direct degradation of ethyl carbamate by enzymes and microorganisms, and different technological methods of grape cultivation, alcoholic fermentation, wine aging, temperature and duration of storage and transportation.

Insights into microbial communities and metabolic profiles in the traditional production of the two representative Hongqu rice wines fermented with Gutian Qu and Wuyi Qu based on single-molecule real-time sequencing

Hongqu rice wine, a famous traditional fermented alcoholic beverage, is brewed with traditional Hongqu (mainly including Gutian Qu and Wuyi Qu). This study aimed to compare the microbial communities and metabolic profiles in the traditional brewing of Hongqu rice wines fermented with Gutian Qu and Wuyi Qu. Compared with Hongqu rice wine fermented with Wuyi Qu (WY), Hongqu rice wine fermented with Gutian Qu (GT) exhibited higher levels of biogenic amines. The composition of volatile flavor components of Hongqu rice wine brewed by different fermentation starters (Gutian Qu and Wuyi Qu) was obviously different. Among them, ethyl acetate, isobutanol, 3-methylbutan-1-ol, ethyl decanoate, ethyl palmitate, ethyl oleate, nonanoic acid, 4-ethylguaiacol, 5-pentyldihydro-2(3H)-furanone, ethyl acetate, n-decanoic acid etc. were identified as the characteristic aroma-active compounds between GT and WY. Microbiome analysis based on high-throughput sequencing of full-length 16S rDNA/ITS-5.8S rDNA amplicons revealed that Lactococcus, Leuconostoc, Pseudomonas, Serratia, Enterobacter, Weissella, Saccharomyces, Monascus and Candida were the predominant microbial genera during the traditional production of GT, while Lactococcus, Lactobacillus, Leuconostoc, Enterobacter, Kozakia, Weissella, Klebsiella, Cronobacter, Saccharomyces, Millerozyma, Monascus, Talaromyces and Meyerozyma were the predominant microbial genera in the traditional fermentation of WY. Correlation analysis revealed that Lactobacillus showed significant positive correlations with most of the characteristic volatile flavor components and biogenic amines. Furthermore, bioinformatical analysis based on PICRUSt revealed that microbial enzymes related to biogenic amines synthesis were more abundant in GT than those in WY, and the enzymes responsible for the degradation of biogenic amines were less abundant in GT than those in WY. Collectively, this study provides important scientific data for enhancing the flavor quality of Hongqu rice wine, and lays a solid foundation for the healthy and sustainable development of Hongqu rice wine industry.