Fermentation Starter Research Articles

A Comparative Analysis of Aroma Profiles of Soju and Other Distilled Spirits from Northeastern Asia

The soju (Korean traditional distilled liquor) market is increasing worldwide. However, in contrast to well-explored distilled liquors, including baijiu (China) and shochu (Japan), soju is less investigated, with limited research on its aroma characteristics. To facilitate better understanding of the aroma characteristics of soju, this study aims to overview recent research on the flavor characteristics of soju and compare data with those of baijiu and shochu, well-established products in the market. Soju is generally made using rice and nuruk (a traditional Korean fermentation starter). Previous studies have reflected that the aroma characteristics vary with raw materials’ nutrition percentages, microbial taxa influenced in fermentation starters, and/or pressure reduction during distillation. The research on the aroma characteristics of baijiu, characterized by solid-state fermentation involving qu (a traditional Chinese fermentation starter), is focused on differences in regional characteristics of the flavor type. Research on the aroma characteristics of shochu has primarily demonstrated that the microbial community could contribute significantly to the development of specific aromatic compounds and/or attributes. Moreover, the association of the aroma characteristics of baijiu and shochu with their volatile compound development by the determination of selective ingredients has been examined. Understanding the current research progress can potentially facilitate the improvement in the aroma characteristics of soju.

Screening appropriate lactic acid bacteria as adjunct starter to enhance characteristic flavor and sensory profiles of Huangjiu (Chinese rice wine)

Lactic acid bacteria (LAB) are crucial for enhancing Huangjiu flavor, yet no standardized criteria exist for selecting LAB strains for this purpose. This study aimed to investigate the suitability of screening appropriate LAB strains as adjunct starters for Huangjiu fermentation. Twenty-five LAB strains were assessed for their stress resistance and fermentation characteristics. Co-fermentation with Saccharomyces cerevisiae was conducted to explore its role in flavor development, as this yeast greatly contribute to desirable flavor profiles. Notably, Lactiplantibacillus plantarum AR1018, AR1026 and Weissella confusa AR1038 significantly reduced 3-methyl-1-butanol production while increasing levels of ethyl hexanoate and ethyl octanoate. These strains were selected for further analysis of their impact on the physicochemical properties, volatile organic compounds, and sensory attributes of Huangjiu. The LAB starters enhanced total acidity, sugar and protein utilization and ester synthesis, while reducing ethanol and alcohol levels. AR1018 achieved a 16.51% reduction in 3-methyl-1-butanol, whereas AR1038 exhibited a 27.32% increase in ester content compared to the control. Principal component analysis revealed distinct flavor characteristic between Huangjiu produced with AR1018 and AR1038, and sensory evaluation confirmed enhanced desirable attributes, especially for AR1038. This study highlights the potential of LAB starters in improving the flavor quality of rice wine and similar fermented beverages.

Use of Indigenous Lactic Acid Bacteria for Industrial Fermented Sausage Production: Microbiological, Chemico-Physical and Sensory Features and Biogenic Amine Content

The use of starter cultures in the meat industry is common, even if the number of available commercial cultures is limited, inducing product standardisation and microbial diversity reduction. On the other hand, some artisanal products relying on spontaneous fermentation can represent a source of isolation of new interesting strains. In this work, four LAB strains derived from Mediterranean spontaneously fermented sausages were tested as new starter cultures for the industrial production of fermented sausages, in comparison to a commercial starter culture. The products obtained were analysed for physico-chemical parameters, microbiota, biogenic amines and aroma profile. A consumer test was also performed to evaluate product acceptability. The strains induced different acidification kinetics. LAB counts showed high persistence when Latilactobacillus curvatus HNS55 was used as the starter culture, while the addition of Companilactobacillus alimentarius CB22 resulted in a high concentration of enterococci (6 log CFU/g), 2 log higher than in other samples. Tyramine was detected at concentrations of 150–200 mg/kg, except for in the sample produced with Lactiplantibacillus plantarum BPF2 (60 mg/kg). Differences were observed in the aroma profile, with a high amount of 2-butanone found in the samples obtained with Comp. alimentarius CB22. These latter sausages also showed the lowest score in terms of acceptability. This study allowed us to select new LAB strains for fermented sausage starter cultures, increasing the product diversification.

Metagenomics reveals the differences in flavor quality of rice wines with Hongqu and Maiqu as the fermentation starters

Chinese rice wine (CRW) is an alcoholic beverage made mainly from rice or grain through saccharification and fermentation with Jiuqu (starter). Jiuqu makes an important contribution to the formation of the flavor characteristics of rice wine. Hongqu and Maiqu are two kinds of Jiuqu commonly used in CRW brewing. This study compared the microbial community, biogenic amines (BAs), and volatile flavor components (VFCs) of two types of rice wine brewed with Hongqu and Maiqu as fermentation agents. The results showed that the amino acid content of rice wine fermented with Maiqu (MQW) was significantly lower than that of rice wine fermented with Hongqu (HQW). On the contrary, the majority of BAs in MQW were significantly higher than those in HQW, except for putrescine. Multivariate statistical analysis indicated that most of the VFCs detected were enriched in HQW, while ethyl 3-phenylpropanoate and citronellol were enriched in MQW. The results of metagenomic analysis showed that Weissiella, Enterobacter, Leuconostoc, Kosakonia, Saccharomyces, Aspergilus and Monascus were identified as the predominant microbial genera in HQW brewing process, while Saccharopolyspora, Lactococcus, Enterobacter, Leuconostoc, Kosakonia, Pediococcus, Pantoea, Saccharomyces, Aspergillus, Lichtheimia and Nakaseomyces were the predominant microbial genera in MQW brewing. In addition, some VFCs and BAs were strongly correlated with dominant microbial genera in HQW and MQW brewing. Bioinformatics analysis showed that the abundance of genes involved in BAs synthesis in MQW brewing was much higher than that in HQW brewing, while the abundances of genes related to metabolic pathway of characteristic VFCs in HQW brewing were obviously higher than those in MQW, which explained the differences in flavor quality between HQW and MQW from the perspective of microbial genes. Collectively, these findings provide scientific evidence for elucidating the contribution of different microbial genera to the formation of flavor quality of CRW, and is helpful for screening beneficial microbes to enhance flavor quality and drinking comfort of CRW.

Enhancing Food Sustainability through Probiotics Isolated from Fermented Cauliflower

In the face of increasing challenges to sustainable food production, biotechnology offers solutions to support the environmental and health aspects of the food industry. This study explores the probiotic potential of L. plantarum and L. brevis isolated from fermented cauliflower. The probiotic properties of the strains and their biochemical characteristics were comprehensively assessed. They have been shown to be resistant to conditions in the human gastrointestinal tract and are able to adhere to colonic epithelial cells. Beneficial properties, such as antimicrobial activity and the production of phenolic acid and exopolysaccharides, were confirmed. The safety of these isolates was established, highlighting their suitability as pro- and prebiotics, and as fermentation starters. In particular, C5 and C2 strains have shown promising industrial potential, with C5 excelling in overall performance and C2 exhibiting strong antagonism to pathogenic strains and superior adhesion to intestinal cells. The resilience of strain C5 under various stress conditions and the exceptional exopolysaccharide production by strain C2 further underscore their unique capabilities and potential applications. These distinct properties make them particularly suitable for applications in functional foods and health-oriented products. These results emphasize the importance of fermented foods in promoting sustainable agricultural practices and consumer health, contributing to a more sustainable food industry.

Kuratsuki Bacteria Interactions with Sake Yeast and Effect on Taste

Various microorganisms, referred to as kuratsuki microorganisms, inhabit each sake brewery. Previously, kuratsuki yeasts had been used for sake production in each sake brewery. Kuratsuki lactic acid bacteria have been used to produce kimoto, a fermentation starter. Kuratsuki non-lactic acid bacteria were examined to evaluate their potential roles and effects in sake production. The addition of kuratsuki bacteria to the sake-making process can change the flavor and taste of the sake. This change was observed in both the coculture experiments between sake yeast and kuratsuki bacteria and the sake making tests with and without kuratsuki bacteria. The comprehensive gene expression analysis of sake yeast cocultured with kuratsuki bacteria showed that 1.2% of the yeast genes were upregulated and 1.0% were downregulated following the addition of kuratsuki bacteria. This indicates that the change in flavor and taste of sake due to the addition of kuratsuki bacteria was caused by the interaction between sake yeast and kuratsuki bacteria. To understand the implications of kuratsuki bacteria in sake production, it is essential to study the interactions between sake yeast and kuratsuki bacteria.

Legendary fermented herbs: an ethnobotanical study of the traditional fermentation starter of the Chuanqing people in Northwestern Guizhou, China

BackgroundPlants that contain brewing microorganisms are used in traditional fermentation starters, which are an essential part of local diet, nutrition, life, and health. Regionally, the plant species used and the microorganisms included in traditional fermentation starters are diverse, endowing local fermented drinks with different flavors and health benefits. However, related traditional knowledge has been scarcely documented or revealed.MethodsAn ethnobotanical survey was conducted in five towns of Nayong County in northwestern Guizhou, China. Snowball sampling, semi-structured interviews, free lists, and participatory observation were used to collect information on Jiuqu Plants (JPs) and jiuqu-making techniques. The PacBio platform was used to study the microbial community structure and diversity in the Chuanqing people’s jiuqu.ResultsIn total, 225 informants were interviewed, including 116 who provided plants and technological processes for making Chinese baijiu jiuqu (CBJ) and 139 who provided information about making fermented glutinous rice jiuqu (FGRJ). This study found that older people have more abundant knowledge about CBJ plants. Poaceae was found to be the dominant family used in making CBJ and FGRJ (7 species each). Compared to individual plant parts, the whole plant is most commonly used in two kinds of jiuqu (19.5% in CBJ and 22.6% in FGRJ). The Chuanqing people’s jiuqu is used to treat dietary stagnation and indigestion. The highest relative frequency of citation of the CBJ plant was Ficus tikoua Bureau, and the counterpart of the FGRJ plant was Buddleja macrostachya Benth. The dominant bacterial species in jiuqu were Gluconobacter japonicus (YQ1, YQ4) and Pediococcus pentosaceus (YQ2, YQ3), and the dominant fungal species was Rhizopus oryzae.ConclusionFor the first time, this study documents the unique traditional jiuqu knowledge and reveals the microbial mystery behind the FGRJ of the Chuanqing people.Therefore, this study encourages the use of online social media platforms in order to spread Jiuqu culture, the use of the new media wave in order to create multimedia databases, and also suggests that local communities should develop preservation intervention programs, in addition to nurturing the inheritors in order to prevent the disappearance of traditional Jiuqu knowledge. This research contributes to the conservation and demystification of the traditional jiuqu knowledge of the Chuanqing people and lays the foundation for further research on its microbiology, nutrition, and metabolomics.

Fermentation starters and bacteriocins as biocontrol strategies for table olives preservation: a mini-review.

Biopreservation is a powerful strategy to prolong the shelf life of food products by applying naturally occurring microorganisms and/or their metabolites. Current food trends emphasise the need to develop alternatives for chemical or thermal preservation methods. In this line, different fermentation starters from table olives present the potential to control spoilage or pathogen-occurring microorganism in table olives storage. One of the most interesting family used as biopreservative culture is Lactobacillaceae and it has also been used in combination with yeasts as olive fermentation starter. Lactic acid bacteria, from Lactobacillaceae family, are characterised by the production of bacteriocins, proteins with the potential for preserving food by changing the organisation of the membrane of spoilage microorganisms. These bacteriocins-producing bacteria can be directly inoculated, although nanosystem technology is the most promising incorporation strategy. In table olives, the most commonly used starters are Lactiplantibacillus plantarum, Lactiplantibacillus pentosus, Saccharomyces cerevisiae, Wickerhamomyces anomalus, among others. These strains with biopreservation characteristics, inoculated alone or in mixed cultures, ensure food safety by conferring the product added value and prolonging product shelf life. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

High-Throughput Sequencing Analysis of Microbiota and Enzyme Activities in Xiaoqu from Seven Provinces in Southern China.

Xiaoqu, a pivotal starter in baijiu fermentation, provides the most microflora and enzymes to initiate and maintain baijiu brewing. This study aims to explore the differences in microbiota and enzyme activities among Xiaoqu samples from seven provinces in southern China using high-throughput sequencing, plate isolation, and activity detection. The analyses revealed significant differences in bacterial and fungal communities across the samples. A total of 22 bacterial species and 17 target fungal species were isolated and identified. Predominant bacteria included Bacillus (Bacillus subtilis) and lactic acid bacteria (LABs), while the fungal communities were primarily composed of yeasts (Saccharomyces cerevisiae) and various molds. The activities of α-amylase and glucoamylase varied significantly among the samples, and samples from HN1 and GZ2 exhibited the highest activities. Correlation analyses highlighted the pivotal role of LABs in maintaining acidity and the importance of molds and yeasts in the saccharification and fermentation processes. These findings shed light on the microbial composition and diversity of Xiaoqu and the critical role of microbes in baijiu production. Moreover, they suggested potential microbial resources for developing artificial Xiaoqu via synthetic microbial community in the future, enhancing baijiu fermentation efficiency and overall product quality.

Genomic and metabolomic analysis of Latilactobacillus sakei DCF0720 for black soybean yogurt fermentation

Lactic acid bacteria are commonly used in plant-based fermentation to reduce off-flavor and improve sensory characteristics. However, there have been few studies on Latilactobacillus sakei for plant-based yogurt fermentation and, particularly, its metabolic features at the genomic level remain unclear. This study aims to analyze the fermentation characteristics of the L. sakei DCF0720 strain and compare genetics and metabolic relations. For this, DCF0720 was used to ferment the black soybean milk and conduct the physicochemical analysis and sensory test. The genomic and metabolic analyses were performed by complete genome sequencing and 500 MHz 1H NMR, respectively. As a result, DCF0720 exhibited enhanced fermentation performance and sensory evaluations at 37 °C compared to 30 °C, which is generally recognized as the optimal growth temperature for most L. sakei strains. It also produced flavor enhancing volatile compounds such as acetoin and hydroxyacetone, possessing all three key genes for acetoin biosynthesis. DCF0720 lacks 2,3-butanediol dehydrogenase, which leads to the inhibition of acetoin production. DCF0720 possesses a complete pathway to utilize primary black soybean carbon sources such as sucrose, raffinose, and stachyose. DCF0720 also possesses genes for the GH28 family, including the key enzymes in the hydrolysis of pectin substances, which means eliminating the main soybean nonstarch polysaccharides. This study demonstrates that DCF0720 is a suitable starter for plant-based yogurt fermentation, providing a better understanding of fermentation conditions with genetic and metabolic features for black soybean yogurt. Various carbon source utilization abilities with depth metabolic pathway analysis provide that DCF0720 can be employed to develop enhanced starter cultures for black soybean yogurt and diverse plant-based yogurts.

Improved Functions of Fermented Coffee by Lactic Acid Bacteria

Coffee is one of the most popular beverages in the world, and at present, specialty coffees are developing for better tastes, flavors, or functions. Fermented coffees also reflect this trend and some brands are commercialized. Unlike general fermented coffees, we tried to ferment coffee extract with several lactic acid bacteria. Finally, we selected three strains that persisted in the coffee extract, and show strong antimicrobial activity, for the fermentation starters. The strains were identified as Pediococcus pentosaceus (KNUT 0384), Lacticaseibacillus paracasei (CJNU 1840), and Lactiplantibacillus plantarum (CJNU 0441) based on 16S rRNA gene sequences. During the fermentation process, the total acidities (p < 0.05 vs. the control, non-fermented coffee extract) and cell masses increased, which indicates that the bacteria metabolized properly in the extract. Furthermore, the fermented coffee extracts showed increased antimicrobial activities against Listeria monocytogenes (p < 0.05 vs. the control) and Streptococcus mutans (p < 0.05 vs. the control), increased anti-oxidative activities (p < 0.05 vs. the control, except for the KNUT 0384 sample), decreased caffeine content (p < 0.05 vs. the control, except for the KNUT 0384 sample), and increased chlorogenic acid content (p < 0.05 vs. the control). Taken together, the fermented coffee extracts with the selected lactic acid bacteria could be specialty coffees where several functions are improved when compared with a control coffee extract.

Microbiota of arabica coffee: insights from soil to fruit.

Studies have shown that a diverse and metabolically active microbiota exists throughout different stages of coffee processing, from pre- to post-harvest. This microbiota originates from both the cultivation and processing environments. Additionally, microorganisms from the soil can be found on the fruit due to the transfer between them. This study reviews the microbiota present in Arabica coffee fruits and the soils where the plants are grown. It examines how microbial profiles are related to coffee variety, altitude, cultivation region, and processing method, and establishes a connection between the microbiota in soil and fruit. A diverse microbiota was observed in both coffee fruits and soils, with similar microorganisms identified across different growing regions, processing methods, and coffee varieties. However, exclusive detections of some microorganisms were also observed. These differences highlight the influence of terroir on coffee's microbial composition, confirming that environmental conditions, genetic factors, and processing methods shape coffee microbiota. Since microbial development during coffee fermentation can affect the beverage's quality, the data presented in this review offer valuable insights for researchers and producers. Understanding the influence of processing methods, coffee varieties, and cultivation regions on coffee microbiota enables the selection of specific fermentation conditions or starter cultures to enhance terroir characteristics or adjust microbial populations to favor or introduce microorganisms beneficial for coffee quality.

Deciphering the effects of different types of high-temperature Daqu on the fermentation process and flavor profiles of sauce-flavor Baijiu

The fermentation of sauce-flavor Baijiu requires high-temperature Daqu as the starter, which is classified into three types: white, yellow, and black. Recent studies highlighted the variability of the microbiota and metabolome profiles of these three types of Daqu, however, what functions they precisely provide in the sauce-flavor Baijiu brewing process remains unclear. In this study, white, yellow, and black Daqu in five different proportions were utilized as starters in field-scale Baijiu fermentation, with the control group lacking Daqu inoculation. Fermented grains inoculated with 100% white Daqu (47.7 °C) had the highest temperature during stacking fermentation, while 100% black Daqu and control groups were lower than 45 °C. Lactic acid (12.6–22.0 mg/g) was the most abundant organic acid, followed by acetic acid (0.7–5.0 mg/g). qPCR analysis revealed that bacterial biomass decreased during fermentation, while fungal biomass increased. A comparison with the control revealed that Daqu contributed high-temperature resistant microorganisms to the stacking fermentation process, primarily Kroppenstedtia, Virgibacillus, Byssochlamys, Thermoascus, and Thermomyces. Meanwhile, stacking fermentation promoted the enrichment of Acetobacter, Kazachstania, and Leiothecium. Mantel test and co-occurrence network analysis revealed that utilizing different fermentation starters could vary the biotic and abiotic factors that drive microbial community succession. We investigated the flavor of Baijiu further, and found that fermentation with white Daqu enhanced the accumulation of ethyl acetate, isoamyl alcohol, and isobutanol, whereas black Daqu increased the accumulation of ethyl lactate, lactic acid, and furfural. This study contributes to the rational usage of different types of Daqu in the manufacturing of Baijiu.

BIODIVERSITY OF CELLULOLYTIC BACTERIA ISOLATED FROM FERMETODEGE FOR RUMINANTS

ARTICLE HIGLIGHTS- Fermetodege as a source of cellulolytic bacteria that degrade cellulosic materials.- Enhances ruminant feed by improving palatability and digestibility.- Utilizes water hyacinth, reducing invasive plant spread and supporting ecosystems.- Bioprospecting reveals new bacteria for effective fermentation starter development.ABSTRACTFermetodege is a name of fermented ruminant feed produced from free heavy metals water hyacinth, rice bran, and corn cobs. Its quality, as well as the fermentation process, are affected by numerous factors, such as the diversity, evenness, and dominance of indigenous cellulolytic bacterial species. A proper understanding of these influential factors is needed to improve the quality of the fermented feed. Therefore, this study aims to evaluate the diversity, evenness, and dominance of cellulolytic bacteria isolated from fermetodege. The cellulolytic activity of the isolates was tested by observing their growth on the carboxymethylcellulose (CMC) media. Isolates with cellulolytic activity formed a clear zone after the colonies were soaked with 0.1% Congo red and rinsed with 1 M NaCl. The Shannon-Weiner's diversity and evenness indexes, as well as Simpson's species dominance, were then calculated. The result showed that the Shannon-Weiner’s diversity index ranged from 0.6849 to 1.8173, and it was categorized as medium. The evenness index was between 0.7778 and 0.9983, which indicates a stable distribution of species. Meanwhile, the Simpson’s species dominance ranged from 0.1835 to 0.5082, which implies that none of the species was dominant. These results show that fermetodege is potentially a source of bacterial isolates and can be used as a fermentation consortium starter.

A Comparative Study of Microbial Communities, Biogenic Amines, and Volatile Profiles in the Brewing Process of Rice Wines with Hongqu and Xiaoqu as Fermentation Starters.

Rice wine is primarily crafted from grains through saccharification and liquification with the help of Qu. Qu plays an important role in the formation of the flavor quality of rice wine. Hongqu and Xiaoqu represent two prevalent varieties of Qu that are typically utilized in the brewing process of rice wine and play a crucial role in its production. In this study, GC, GC-MS, HPLC, and metagenomic sequencing techniques were used to contrast the microbial flora, biogenic amines, and aroma characteristics developed during the fermentation of rice wines, with Hongqu and Xiaoqu being used as initiating agents for the brewing process. The results show that the content of higher alcohols (including n-propanol, isobutanol, 3-methyl-1-butanol, and phenethyl alcohol) in rice wine brewed with Xiaoqu (XQW) was significantly higher than that in rice wine brewed with Hongqu (HQW). Contrarily, the concentration of biogenic amines in HQW surpassed that of XQW by a notable margin, but tyramine was significantly enriched in XQW and not detected in HQW. In addition, a multivariate statistical analysis revealed distinct disparities in the constitution of volatile components between HQW and XQW. Hexanoic acid, ethyl acetate, isoamyl acetate, ethyl caproate, ethyl decanoate, 2-methoxy-4-vinylphenol, etc., were identified as the characteristic aroma-active compounds in HQW and XQW. A microbiome analysis based on metagenomic sequencing showed that HQW and XQW had different dominant microorganisms in the brewing process. Burkholderia, Klebsiella, Leuconostoc, Monascus, and Aspergillus were identified as the primary microbial genera in the HQW fermentation period, while Pediococcus, Enterobacter, Rhizopus, Ascoidea, and Wickerhamomyces were the main microbial genera in the XQW brewing process. A bioinformatics analysis revealed that the concentrations of microbial genes involved in biogenic amines and esters biosynthesis were significantly higher in HQW than those in XQW, while the content of genes relevant to glycolysis, higher alcohol biosynthesis, and fatty acid metabolism was significantly higher in XQW than in HQW, which are the possible reasons for the difference in flavor quality between the two kinds of rice wine from the perspective of microbial functional genes.

The impact of lactic acid bacteria inoculation on the fermentation and metabolomic dynamics of indigenous Beijing douzhi microbial communities.

Douzhi, a traditional Chinese fermented beverage, features microbial communities primarily composed of lactic acid bacteria (LAB). As fermented foods continue to gain recognition and popularity, douzhi is attracting growing interest. However, investigation of the critical aspects of douzhi's fermentation processes, including fermentation characteristics and microbial community dynamics, remains vital for enhancing food safety and quality for douzhi, as well as for similar fermented food products. In this study, we collected douzhi microbial communities from four chain stores, using them as fermentation starter cultures. The microbial dynamics of the fermentation were analyzed, focusing on the inoculation of LAB strains and the transition from a mung bean-based matrix to skimmed milk. The metabolomic profiles of the fermented mung bean matrices were also studied. Douzhi samples obtained from representative chain stores were found to be overwhelmingly dominated by LAB. When inoculated along with the douzhi community, both LAB strains exhibited notable and substantial reductions in the pH value of the designated mung bean matrices compared to those inoculated indigenous microbiota. Specifically, Lactiplantibacillus plantarum CGMCC 1.1856 retained its population, whereas Pediococcus pentosaceus CGMCC 1.2695 exhibited a decrease in relative abundance. Using skimmed milk as a fermentation substrate instead of the mung bean matrix resulted in significant shifts in microbial communities, particularly leading to an increase in Escherichia sp. The metagenomic analyses and functional predictions illustrated that various metabolic functions were enhanced during the fermentation process due to LAB inoculation. The liquid chromatography-mass spectrometry based metabolomic analysis revealed that the inoculation of Lactiplantibacillus plantarum and Pediococcus pentosaceus in mung bean matrix did not introduce new metabolites but significantly altered the concentration and profile of existing metabolites, especially increased low molecular carbohydrates, which may enhance the nutritional potential of the fermented product. This study examines the microbial dynamics of douzhi microbiota fermentation, emphasizing the role of lactic acid bacteria in enhancing fermentation activity and metabolite profiles. These insights contribute to improving manufacturing processes and ensuring the safety and quality of douzhi and similar fermented foods.

Deciphering the microbial succession and color formation mechanism of "green-covering and red-heart" Guanyin Tuqu.

"Green-covering and red-heart" Guanyin Tuqu (GRTQ), as a type of special fermentation starter, is characterized by the "green-covering" formed on the surface of Guanyin Tuqu (SQ) and the "red-heart" in the center of Guanyin Tuqu (CQ). However, the mechanisms that promote temporal succession in the GRTQ microbial ecology and the formation of "green-covering and red-heart" characteristics remain unclear. Herein, we correlated the temporal profiles of microbial community succession with the main environmental variables (temperature, moisture, and acidity) and spatial position (center and surface) in GRTQ throughout fermentation. According to the results of high-throughput sequencing and culture-dependent methods, the microbial communities in the CQ and SQ demonstrated functional complementarity. For instance, the bacterial richness index of the CQ was greater than that of SQ, and the fungal richness index of the SQ was greater than that of CQ at the later stage of fermentation. Furthermore, Saccharomycopsis, Saccharomyces, Aspergillus, Monascus, Lactobacillus, Bacillus, Rhodanobacter, and Chitinophaga were identified as the dominant microorganisms in the center, while the surface was represented by Saccharomycopsis, Aspergillus, Monascus, Lactobacillus, Acetobacter, and Weissella. By revealing the physiological characteristics of core microorganisms at different spatial positions of GRTQ, such as Aspergillus clavatus and Monascus purpureus, as well as their interactions with environmental factors, we elucidated the color formation mechanism behind the phenomenon of "green" outside and "red" inside. This study provides fundamental information support for optimizing the production process of GRTQ.

The biological integrity of natural poly-species symbiotic bacterial communities for the production of kefir: Basic aspects of the preservation

An integral step in kefir production technology is the use of kefir grains, but in some cases it is necessary to maintain their population at the plant. A convenient method is freezing, but with direct freezing, kefir grains lose activity and some microorganisms die off. The use of substances with cryoprotective properties can help preserve kefir grains under direct freezing conditions. The study has examined three environments that have the potential to protect the symbiosis of kefir grains under subcryoscopic conditions: skim sterile milk, gelatin and a sterile solution of 30 % sucrose, and one environment that is stressful – sterile distilled water. At previous stages of research, it was proven that sharp defrosting aggravates the stress phenomena of the bacterial community, in particular, promotes the death of surface lactococci which leads to dysbacteriosis of the symbiosis. The work used for the first time a periodic scheme for defrosting kefir grains in a protective environment; the methods of visual and organoleptic assessment have been applied, the studies of microbiological and physico-chemical parameters of milk after fermentation of kefir starter with kefir grains have been conducted. Milk changes have been carried out using the technology of cultivating kefir grains with daily passages. It is accepted that if based on a set of indicators kefir grains from the experimental groups within 7 days correlate with the indicators detected for the control group, which was not subjected to freezing, then it is accepted that the kefir grains have completely restored viability. If this does not happen, a conclusion is drawn that the symbiosis has not been restored. As a result of the research, the prospects for using the studied substances as protective media have been proven and the need to construct specialized cryoprotective media for direct freezing of kefir grains in order to create your own kefir culture banks has been substantiated. The approach will reduce the use of bacterial substitutes for kefir like direct fermentation starters.

Pemanfaatan Bakteri Asam Laktat (BAL) Amilolitik untuk Fermentasi Tepung Terigu dan Gandum

The national demand for carbohydrates in flour continues to increase significantly due to the emergence of contemporary food products that use flour as the primary ingredient. One of the products used in producing food is sourdough, which is fermented flour. Lactic acid bacteria (LAB) have a role in food fermentation by producing lactic acid. Amylolytic LAB can produce amylase enzyme, a biocatalyst in the starch hydrolysis process. One of the products made from the fermentation of wheat flour is sourdough. This study aims to determine the character of amylolytic LAB in wheat and wheat flour fermentation. The research methods include rejuvenation of LAB, selection of isolates, fermentation of starchy materials, and characterization of fermented liquid. The selection of bacteria was based on cell viability and pH, which showed that isolated Pediococcus pentasaceus E1222 could be used as a starter for starchy fermentation. The highest total acid and cell viability were produced in 24-hour wheat and wheat flour fermentation. Fermented wheat flour and flour had the most favorable aroma and texture, and fermented flour had the most favorable taste. Isolate Pediococcus pentasaceus E1222 is an isolate that can be used in making sourdough.

Efficiency of freeze- and spray-dried microbial preparation as active dried starter culture in kombucha fermentation.

Kombucha is a widely consumed fermented beverage produced by fermenting sweet tea with a symbiotic culture of bacteria and yeast (SCOBY). The dynamic nature of microbial communities in SCOBY may pose challenges to production scale-up due to unpredictable variations in microbial composition. Using identified starter strains is a novel strategy to control microorganism composition, thereby ensuring uniform fermentation quality across diverse batches. However, challenges persist in the cultivation and maintenance of these microbial strains. This study examined the potential of microencapsulated kombucha fermentation starter cultures, specifically Komagataeibacter saccharivorans, Levilactobacillus brevis and Saccharomyces cerevisiae, through spray-drying and freeze-drying. Maltodextrin and gum arabic-maltodextrin were employed as carrier agents. Our results revealed that both spray-dried and freeze-dried samples adhered to physicochemical criteria, with low moisture content (2.18-7.75%) and relatively high solubility (65.75-87.03%) which are appropriate for food application. Freeze-drying demonstrated greater effectiveness in preserving bacterial strain viability (88.30-90.21%) compared to spray drying (74.92-78.66%). Additionally, the freeze-dried starter strains demonstrated similar efficacy in facilitating kombucha fermentation, compared to the SCOBY group. The observations included pH reduction, acetic acid production, α-amylase inhibition and elevated total polyphenol and flavonoid content. Moreover, the biological activity, including antioxidant potential and in vitro tyrosinase inhibition activity, was enhanced in the same pattern. The freeze-dried strains exhibited consistent kombucha fermentation capabilities over a three-month preservation, regardless of storage temperature at 30 or 4 °C. These findings highlight the suitability of freeze-dried starter cultures for kombucha production, enable microbial composition control, mitigate contamination risks and ensure consistent product quality. © 2024 Society of Chemical Industry.