Dynamics of Microbial Communities, Flavor, and Physicochemical Properties during Ziziphus jujube Vinegar Fermentation: Correlation between Microorganisms and Metabolites

Insight into the impact of various processing stages on metabolites and flavors in jujube jam

Essential to the determination of the ultimate and flavor of jujube jam are various processing stages. Nevertheless, the alterations in metabolites and flavor chemistry throughout the processing of jujube jam are poorly comprehended. This research employed metabolomics, flavor analysis, and microbial indicators to examine the impact of distinct processing stages on the metabolites and flavor profile of jujube jam. The research findings indicated that the sterilization stage (SJ) was the most favorable stage for metabolite accumulation. Hexahydro-pseudoketone and 2-methylbutyraldehyde, compounds responsible for off-odors, exhibited a significant reduction following the concentration stage (NS). The distinctive flavors detected in jujube jam included floral, citrus, sweet and sour, as well as cheesy notes. Furthermore, the alterations observed in microbial indicators confirmed that the jujube jam products adhered to the established jam production benchmarks. In summary, these findings offer a foundational framework for the creation of a regulated processing system and for the improvement of jujube jam quality, thereby providing valuable guidance for the targeted production of premium jujube jam.

Correlating Microbial Dynamics with Key Metabolomic Profiles in Three Submerged Culture-Produced Vinegars

Although vinegar is a product obtained by a well-known bioprocess from a technical point of view, the complex microbiota responsible for its production and their involvement in the organoleptic profiles are not clear yet. In this work, three acetification profiles in submerged culture using both synthetic and raw materials from Andalusia (Spain) were characterized by metagenomic (16S rRNA amplicon sequencing) and metabolomic tools (stir-bar sorptive extraction with thermo-desorption coupled to gas chromatography-mass spectrometry (SBSE-TD-GC-MS) and high-performance liquid chromatography (HPLC)). A total of 29 phyla, 208 families, and many more genera were identified, comprising bacteria and archaea as well as 75 metabolites, including minor volatile compounds, amino acids, biogenic amines, and other nitrogenous compounds. It can be concluded that Komagataeibacter and Acetobacter were not only the predominant genera but also the ones that most influenced vinegar metabolite profiles by using different metabolic strategies for mutual collaboration, and together with other microbial groups, some of them were previously practically unknown in vinegar. These results can be of interest not only to deepen the basic knowledge about vinegar but also to the vinegar industry by elucidating microbial succession and the key associated metabolites.

Microbial community succession and changes of volatile compounds in the fermentation process of bamboo shoots

Sour bamboo shoots are a traditional fermented delicacy that has garnered appreciation both domestically and internationally. This study investigates the intricate dynamics of microbial communities and volatile flavor compounds primarily derived from salted and pickled bamboo shoots during the fermentation process of Phyllostachys purpurea (PP). The dynamics of microorganisms and volatile flavor compounds were thoroughly examined initially using conventional isolation and cultivation methods in conjunction with high-throughput sequencing (HTS), headspace solid-phase microextraction (HS-SPME), and gas chromatography-mass spectrometry (GC-MS). In addition, we analyzed the core microorganisms responsible for modulating the volatile flavor profile. Our findings revealed 60 volatile compounds, 14 of which were the predominant contributors to the aroma of fermented PP. This group primarily comprised alcohols, aldehydes, and olefins. Notably, our investigation identified Lactobacillus and Candida as the dominant microbial genera during the middle and late stages of fermentation. These two genera exert a significant influence on the formation of characteristic aromas. Furthermore, we discovered that acids, sugars, and proteins pivotally influence the succession of microorganisms. Specifically, acids and soluble sugars drove the transition of Lactococcus to Lactobacillus and Pediococcus, whereas soluble proteins facilitated fungal succession from Candida to Kazachstania and Issatchenkia. These insights shed light on the community structure and succession patterns of flavor compounds throughout the PP fermentation process. Ultimately, they provide a foundation for optimizing the fermentation process and ensuring quality control in the production of sour bamboo shoots.

From flavor to function: A review of fermented fruit drinks, their microbial profiles and health benefits

Fermented fruit drinks (FFDs) are gaining popularity among consumers for their unique flavors and potential health benefits. This review provides a systematic assessment of the flavor components in FFDs and explores the metabolic pathways for their formation. We examine the interactions between the structure of microbial communities and the development of these flavor components, highlighting the role of microorganisms in shaping the unique taste of FFDs. Additionally, we discuss the potential health benefits associated with FFDs, focusing on their relationship with microbial communities as supported by existing literature. The review also addresses future prospects and challenges in the field. Our findings indicate key fermenting microorganisms, such as lactic acid bacteria, yeast and acetic acid bacteria, are responsible for producing the distinctive flavor components in FFDs, including alcohols, ketones, aldehydes, esters, and fatty acids. These microorganisms also generate organic acids, amino acids, and carbohydrates, contributing to the drink's complex taste. Furthermore, this fermentation process enhances the bioactivity of FFDs, offering potential health benefits like antioxidant, anti-obesity, anti-diabetic, and anti-cancer properties. These insights are crucial for advancing fermentation technology and developing guidelines for producing nutrient-rich, flavorful FFDs.

Functional Nutrients and Jujube-Based Processed Products in Ziziphus jujuba

Jujube (Ziziphus jujuba Mill.) is the first tree species in China, with a long history and abundant yield. However, fresh jujubes have a short shelf-life and are not resistant to storage. Therefore, more and more processed jujube products are being studied. These processed products can extend the shelf-life of jujubes and attract widespread attention for their rich functional nutrients. This review summarized changes in nutrients of fresh jujube and processed products and the research progress of different preparation methods of jujubes. Meanwhile, the pharmacological effects of bioactive components in jujube-based products were concluded. Jujube and its processed products contain rich polysaccharides, vitamin C, and other functional nutrients, which are beneficial to humans. As the initial processing method for jujubes, vacuum freezing or microwave drying have become the most commonly used and efficient drying methods. Additionally, processed jujube products cannot be separated from the maximum retention of nutrients and innovation of flavor. Fermentation is the main deep-processing method with broad development potential. In the future, chemical components and toxicological evaluation need to be combined with research to bring consumers higher quality functional jujube products and ensure the sustainable development of the jujube industry.

Dynamic changes of microbiota and metabolite of traditional Hainan dregs vinegar during fermentation based on metagenomics and metabolomics

Hainan dregs vinegar (HNDV) is a traditional fermented food in China that is renowned for its unique flavor. HNDV is one of the most popular vinegars in Southeast Asia. However, research on the microorganisms and characteristic metabolites specific to HNDV is lacking. This study investigated the changes in microbial succession, volatile flavor compounds and characteristic non-volatile flavor compounds during HNDV fermentation based on metagenomics and metabolomics. The predominant microbial genera were Lactococcus, Limosilactobacillus, Lactiplantibacillus, and Saccharomyces. Unlike traditional vinegar, l-lactic acid was identified as the primary organic acid in HNDV. Noteworthy flavor compounds specific to HNDV included 3-methylthiopropanol and dl-phenylalanine. Significant associations were observed between six predominant microorganisms and six characteristic volatile flavor compounds, as well as seven characteristic non-volatile flavor compounds. The present results contribute to the development of starter cultures and the enhancement of HNDV quality.

Impacts of Aspergillus oryzae 3.042 on the flavor formation pathway in Cantonese soy sauce koji

To investigate the mechanism of flavor formation during the traditional preparation Cantonese soy sauce koji (TP), the changes of microorganisms, physicochemical properties, and flavor compounds in TP were comprehensively and dynamically monitored by absolute quantitative methods. Results demonstrated that inoculating Aspergillus oryzae 3.042 in TP was crucial role in enhancing enzyme activity properties. Absolute quantification of flavor combined with multivariate statistical analysis yielded 5 organic acids, 15 amino acids, and 2 volatiles as significantly different flavors of TP. Amplicon sequencing and RT-qPCR revealed that the dominant genera were Staphylococcus, Weissella, Enterobacter, Lactic streptococci, Lactobacillus, and Aspergillus, which exhibited a increasing trend in TP. Correlation analysis exhibited that Staphylococcus and Aspergillus were the pivotal genera contributing to the enzyme activities and flavor of TP. The flavor formation network involved lipid and protein degradation, carbohydrate metabolism and other pathways. Simultaneously, TP can appropriately increase the fermentation time to improve product quality.

Correlation Analysis between Microbial Communities and Flavor Compounds during the Post-Ripening Fermentation of Traditional Chili Bean Paste

Chili bean paste is a traditional flavor sauce, and its flavor compounds are closely related to its microflora. This study focused on investigating the content of bioactive compounds, flavor compounds, and microbial communities during the post-ripening fermentation of chili bean paste, aiming to provide a reference for improving the flavor of chili bean paste by regulating microorganisms. Compared to no post-ripening fermentation, the content of organic acids increased significantly (p < 0.05), especially that of citric acid (1.51 times). Glutamic acid (Glu) was the most abundant of the 17 free amino acids at 4.0 mg/g. The aroma profiles of the samples were significantly influenced by fifteen of the analyzed volatile compounds, especially methyl salicylate, methyl caproate, and 2-octanol (ROAV > 1). Latilactobacillus (27.45%) and Pseudomonas (9.01%) were the dominant bacterial genera, and Starmerella (32.95%) and Pichia (17.01%) were the dominant fungal genera. Weissella, Lacticaseibacillus, Pichia, and Kazachstania had positive effects on volatile flavoring compounds, which enriched the texture and flavor of the chili bean paste. Therefore, the microbial-community activity during the post-ripening fermentation is the key to enhance the flavor quality of the product.

The consequences of fermentation metabolism on the qualitative qualities and biological activity of fermented fruit and vegetable juices

Fermentation of fruit and vegetable juices with probiotics is a novel nutritional approach with potential health benefits. Lactic acid fermentation-based biotransformation results in changes in the profile and nature of bioactive compounds and improves the organoleptic properties, shelf life and bioavailability of vitamins and minerals in the fermented juices. This process has been shown to enrich the phenolic profile and bioactivity components of the juices, resulting in a new type of functional food with improved health benefits. Fruits and vegetables are the ideal substrate for microbial growth, and fruit and vegetable juice will produce rich nutrients and a variety of functional activities after fermentation, so that the high-quality utilization of fruits and vegetables is realized, and the future fermented fruit and vegetable juice products have a wide application market. This paper explores the typical fermentation methods for fruit and vegetable juices, investigates the bioactive components, functional activities, and the influence of fermentation on enhancing the quality of fruit and vegetable juices. The insights derived from this study carry significant implications for guiding the development of fermented fruit and vegetable juice industry.

Sour Jujube (Ziziphus jujuba var. spinosa): A Bibliometric Review of Its Bioactive Profile, Health Benefits and Trends in Food and Medicine Applications

Research on the comprehensive utilization of sour jujube and its beneficial properties to human health has attracted extensive attention. This study aims to conduct a bibliometric analysis of the bioactive profile of sour jujube and future trends in applications. The research advancements within this field from 2000 to 2023 were addressed using the Web of Science database and VOSviewer. Among the 322 results, the most frequent keywords of bioactivity are flavonoids, antioxidants, saponins, insomnia, polyphenols, terpenoids and anti-inflammatory; the most studied parts of sour jujube are seeds, fruits and leaves; the published articles with high citations mainly focus on identification, biological effects and different parts distribution of bioactive compounds. The bioactivity of various parts of sour jujube was reviewed considering their application potential. The seeds, rich in flavonoids, saponins and alkaloids, exhibit strong effects on central nervous system diseases and have been well-developed in pharmacology, healthcare products and functional foods. The pulp has antioxidant properties and is used to develop added-value foods (e.g., juice, vinegar, wine). The leaves can be used to make tea and flowers are good sources of honey; their extracts are rich sources of flavonoids and saponins, which show promising medicinal effects. The branches, roots and bark have healing properties in traditional folk medicine. Overall, this study provides a reference for future applications of sour jujube in food and medicine fields.

Correlation Analysis of Microbial Community Changes and Physicochemical Characteristics in Aged Vinegar Brewing

This study aimed to explore key physicochemical characteristics and evolutionary patterns of microbial community structure during the fermentation of aged vinegar. The correlation between microorganisms and physicochemical characteristics during fermentation was examined. The results revealed significant differences in genera at different stages of fermentation. The dominant bacteria in R1 were Bacillus, Lactobacillus, Aspergillus, and Issatchenkia. During the R2 fermentation stage, Lactobacillus, Acetobacter, and Saccharomyces exhibited an upward trend and finally became the dominant bacteria. Aspergillus was the main bacterial genus at the end of overall fermentation. The correlation analysis showed that the bacterial genera significantly positively and negatively correlated with reducing sugars and amino acid nitrogen were the same in Cuqu. Similarly, the bacterial genera significantly positively and negatively correlated with pH and saccharification power were the same. pH, reducing sugar, and saccharification ability were mainly positively correlated with bacterial genera during fermentation. Further, studies found that the overall correlation between fungal communities and physicochemical characteristics was weaker than the correlation with bacteria during fermentation.

Deciphering the brewing process of Cantonese-style rice vinegar: Main flavors, key physicochemical factors, and important microorganisms

Cantonese-style rice vinegar is one of the most important Chinese rice vinegars and is quite popular all over the southeast coast of China, especially in Guangdong. This study identified 31 volatile compounds, including 11 esters, 6 alcohols, 3 aldehydes, 3 acids, 2 ketones, 1 phenol, and 5 alkanes, using headspace solid-phase microextraction-gas chromatography-mass spectrometry. Six organic acids were detected by high performance liquid chromatography. The ethanol content was detected by gas chromatography. During acetic acid fermentation, physicochemical analysis showed that the initial concentrations of reducing sugar and ethanol were 0.0079 g/L and 23.81 g/L, respectively, and the final value of total acid was 46.5 g/L, and the pH value was stable at 3.89. High-throughput sequencing was used to identify the microorganisms, and Acetobacter, Komagataeibacter, and Ralstonia were the top three bacterial genera. Quantitative real-time polymerase chain reaction revealed patterns that were different from those of high-throughput sequencing. The co-occurrence network of microorganisms and the correlation analysis between microorganisms and flavor substances indicate that Acetobacter and Ameyamaea played crucial roles as the main functional AAB, and the failure of Cantonese-style rice vinegar fermentation can be attributed to the abnormal increase in Komagataeibacter. Microbial co-occurrence network analysis indicated that Oscillibacter, Parasutterella, and Alistipes were the top three microorganisms. Redundancy analysis disclosed that total acid and ethanol were the key environmental factors influencing the microbial community. Fifteen microorganisms closely related to the metabolites were identified using the bidirectional orthogonal partial least squares model. Correlation analysis showed that these microorganisms were strongly associated with flavor metabolites and environmental factors. The findings of this study deepen our understanding of the fermentation of traditional Cantonese-style rice vinegar.

Exploring the correlation of metabolites changes and microbial succession in solid-state fermentation of Sichuan Sun-dried vinegar

BACKGROUND

The traditional Sichuan Sun-dried vinegar (SSV) with unique flavor and taste is believed to be generated by the solid-state fermentation craft. However, how microorganisms and their metabolites change along with fermentation has not yet been explored.

RESULTS

In this study, our results demonstrated that the middle and late stages of SSV fermentation were the periods showing the largest accumulation of organic acids and amino acids. Furthermore, in the bacterial community, the highest average relative abundance was Lactobacillus (ranging from 37.55 to 92.50%) in all fermentation stages, while Acetobacters ranked second position (ranging from 20.15 to 0.55%). The number of culturable lactic acid bacteria is also increased during fermentation process (ranging from 3.93 to 8.31 CFU/g). In fungal community, Alternaria (29.42%), Issatchenkia (37.56%) and Zygosaccharomyces (69.24%) were most abundant in different fermentation stages, respectively. Interestingly, Zygosaccharomyces, Schwanniomyces and Issatchenkia were first noticed as the dominant yeast genera in vinegar fermentation process. Additionally, spearman correlation coefficients exhibited that Lactobacillus, Zygosaccharomyces and Schwanniomyces were significant correlation with most metabolites during the fermentation, implying that these microorganisms might make a significant contribution to the flavor formation of SSV.

CONCLUSION

The unique flavor of SSV is mainly produced by the core microorganisms (Lactobacillus, Zygosaccharomyces and Schwanniomyces) during fermentation. This study will provide detailed information related to the structure of microorganism and correlation between changes in metabolites and microbial succession in SSV. And it will be very helpful for proposing a potential approach to monitor the traditional fermentation process.