Quality Of Fermented Foods Research Articles

Real-time PCR-based quantitative microbiome profiling elucidates the microbial dynamic succession in backslopping fermentation of Taiwanese pickled cabbage.

Microbiota succession determines the flavor and quality of fermented foods. Quantitative PCR-based quantitative microbiome profiling (QMP) has been applied broadly for microbial analysis from absolute abundance perspectives, transforming microbiota ratios into counts by normalizing 16S ribosomal RNA (16S rRNA) gene sequencing data with gene copies quantified by quantitative PCR. However, the application of QMP in fermented foods is still limited. QMP elucidated microbial succession of Taiwanese pickled cabbage. In the spontaneous first-round fermentation (FR), the 16S rRNA gene copies of total bacteria increased from 6.1 to 10 log copies mL-1. The dominant lactic acid bacteria genera were successively Lactococcus, Leuconostoc and Lactiplantibacillus. Despite the decrease in the proportion of Lactococcus during the succession, the absolute abundance of Lactococcus still increased. In the backslopping second-round fermentation (SR), the total bacteria 16S rRNA gene copies increased from 7.6 to 9.9 log copies mL-1. The addition of backslopping starter and vinegar rapidly led to a homogenous microbial community dominated by Lactiplantibacillus. The proportion of Lactiplantibacillus remained consistently around 90% during SR, whereas its absolute abundance exhibited a continuous increase. In SR without vinegar, Leuconostoc consistently dominated the fermentation. The present study highlights that compositional analysis would misinterpret microbial dynamics, whereas QMP reflected the real succession profiles and unveiled the essential role of vinegar in promoting Lactiplantibacillus dominance in backslopping fermentation of Taiwanese pickled cabbage. Quantitative microbiome profiling (QMP) was found to be a more promising approach for the detailed observation of microbiome succession in food fermentation compared to compositional analysis. © 2024 Society of Chemical Industry.

Wine Barrel Biofilm as a Source of Yeasts with Non-Conventional Properties.

This study investigated the main microbial groups characterizing the interior surface of oak barrels from different years (1890, 1895, 1920, 1975, 2008) used in the production of vino cotto. The yeasts were characterized for the following properties: γ-aminobutyric acid (GABA) production, antioxidant activity, air-liquid interfacial biofilm formation, and anthocyanin adsorption capacity. Community-level physiological profile analysis revealed that the microbial communities inside the barrels used the tested carbon sources in different manners. The following yeast species were identified: Millerozyma farinosa, Zygosaccharomyces bisporus, Wickerhamiella versatilis, Zygosaccharomyces bailii, Starmerella lactis-condensi, and Zygosaccharomyces rouxii. All the strains were able to produce GABA, and S. lactis-condensi, Z. bisporus and Z. rouxii were the highest producers (more than 600 mg/L). The Z. rouxii and Z. bailii strains showed the highest antioxidant activity. Only seven strains out of ten M. farinosa formed air-liquid interfacial biofilm. None of the M. farinosa strains adsorbed anthocyanins on their cell wall. The other strains adsorbed anthocyanins in a strain-dependent way, and the highest adsorption was observed for the W. versatilis strains. The yeasts isolated in this study could be used to increase the functional properties and the quality of fermented foods and beverages.

Advances in fermented foods revealed by multi-omics: A new direction toward precisely clarifying the roles of microorganisms.

Fermented foods generally comprise a complex micro-ecosystem with beneficial microbiota, functional products, and special flavors and qualities that are welcomed globally. Single-omics analysis allows for a comprehensive characterization of the main microbial factors influencing the function, flavor, and quality of fermented foods. However, the species, relative abundance, viability, growth patterns, and metabolic processes of microorganisms vary with changes in processing and environmental conditions during fermentation. Furthermore, the mechanisms underlying the complex interaction among microorganisms are still difficult to completely understand and analyze. Recently, multi-omics analysis and the integration of multiple types of omics data allowed researchers to more comprehensively explore microbial communities and understand the precise relationship between fermented foods and their functions, flavors, and qualities. Multi-omics approaches might help clarify the mechanisms underpinning the fermentation processes, metabolites, and functional components of these communities. This review clarified the recent advances in the roles of microorganisms in fermented foods based on multi-omics data. Current research achievements may allow for the precise control of the whole industrial processing technology of fermented foods, meeting consumers' expectations of healthy products.

Selection of Non-Saccharomyces Wine Yeasts for the Production of Leavened Doughs

Background: Non-conventional yeasts (NCY) (i.e., non-Saccharomyces) may be used as alternative starters to promote biodiversity and quality of fermented foods and beverages (e.g., wine, beer, bakery products). Methods: A total of 32 wine-associated yeasts (Campania region, Italy) were genetically identified and screened for decarboxylase activity and leavening ability. The best selected strains were used to study the leavening kinetics in model doughs (MDs). A commercial strain of Saccharomyces cerevisiae was used as the control. The volatile organic profiles of the inoculated MDs were analyzed by solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). Results: Most of strains belonged to the NCY species Hanseniaspora uvarum, Metschnikowia pulcherrima, Pichia kudriavzevii, Torulaspora delbruekii, and Zygotorulaspora florentina, while a few strains were S. cerevisiae. Most strains of H. uvarum lacked decarboxylase activity and showed a high leaving activity after 24 h of incubation that was comparable to the S. cerevisiae strains. The selected H. uvarum strains generated a different flavor profile of the doughs compared to the S. cerevisiae strains. In particular, NCY reduced the fraction of aldehydes that were potentially involved in oxidative phenomena. Conclusions: The use of NCY could be advantageous in the bakery industry, as they can provide greater diversity than S. cerevisiae-based products, and may be useful in reducing and avoiding yeast intolerance.

Effects of Salt Treatment Time on the Metabolites, Microbial Composition, and Quality Characteristics of the Soy Sauce Moromi Extract.

Salt is one of the most important factors for fermented foods, but the effect of salt treatment time on the quality of fermented foods has rarely been studied. In this study, the effect of different salt treatment times (0, 48, and 96 h) after the start of fermentation on the quality of the soy sauce moromi extract (SSME) was investigated. As the salt treatment time was delayed, the population of Aspergillus oryzae, Lactobacillaceae, and Enterococcaecea in SSME increased, whereas the population of Staphylococcaceae and Bacillaceae decreased, leading to changes in the enzymatic activity and metabolite profiles. In particular, the contents of amino acids, peptides, volatile compounds, acidic compounds, sugars, and secondary metabolites were significantly affected by the salt treatment time, resulting in changes in the sensory quality and appearance of SSME. The correlation data showed that metabolites, bacterial population, and sensory parameters had strong positive or negative correlations with each other. Moreover, based on metabolomics analysis, the salt treatment-time-related SSME metabolomic pathway was proposed. Although further studies are needed to elucidate the salt treatment mechanism in fermented foods, our data can be useful to better understand the effect of salt treatment time on the quality of fermented foods.

Lactiplantibacillus plantarum 299v as starter culture suppresses Enterobacteriaceae more efficiently than spontaneous fermentation of carrots

Fermentation, especially spontaneous fermentation, has become from an ancient food preservation method to a stylish cooking trend in very recent years. Accordingly, the associated food safety should be revisited, particularly since inexperienced people increasingly performing spontaneous fermentation on an ad hoc basis. In this study, three lactic acid bacteria (LAB) strains were tested. Lactiplantibacillus plantarum 299v at high initial inoculation levels (>6 log CFU/mL brine water) effectively eliminated Salmonella spiked in a carrot fermentation system from 4.6 ± 0.2 log CFU/mL to < 1 log CFU/mL after 7 days fermentation at 20 °C. Next, the bacterial enumeration and 16s rRNA gene sequencing results between spontaneous fermentation and fermentation samples using L. plantarum 299v as the starter culture were compared. It was found that the inhibiting effect of L. plantarum 299v could be extended beyond Salmonella spp. to the entire Enterobacteriaceae family during the carrot fermentation. Therefore, our study suggests that in comparison with spontaneous fermentation, selected starter culture such as L. plantarum 299v can consistently improve the safety and quality of fermented foods.

Sodium Reduction in Traditional Fermented Foods: Challenges, Strategies, and Perspectives.

Sodium salt is a pivotal ingredient in traditional fermented foods, but its excessive consumption adversely affects human health, product quality, and production efficiency. Therefore, reducing sodium salt content in traditional fermented foods and developing low-sodium fermented foods have attracted increasing attention. Given the essential role of sodium salt in the safety and quality of fermented foods, appropriate approaches should be applied in the production of low-sodium fermented foods. In this review, the challenges of sodium reduction in traditional fermented foods are presented, including the possible growth of pathogenic bacteria, the formation of hazardous chemicals, flavor deficiency, and texture deterioration. Physical, chemical, and biological strategies are also discussed. This review provides references for improving the quality and safety of low-sodium fermented foods.

Microbial community diversity of traditional dough starter (Jiaozi) from two provinces in northwest China

PurposeMicrobial community composition is crucial for the flavor and quality of fermented foods. However, the microbiota of Chinese traditional dough starter (Jiaozi) from different origins has scarcely been studied. The aim of this study was to determine the composition of bacterial and fungal communities in six Jiaozi collected from two provinces in northwest China.MethodsOur study determined the composition of bacterial and fungal communities in six Jiaozi through Illumina MiSeq sequencing of the 16S rRNA gene and the ITS regions.ResultA total of 234 operational taxonomic units (OTUs) for bacteria and 490 OTUs for fungi were identified. Furthermore, Lactobacillus, Weissella, Acetobacter, Sphingomonas, and Serratia were identified as the predominant bacterial genera in Jiaozi samples, while Saccharomyces, Candida, Alternaria, unclassified Filobasidiales, and Mycosphaerella were the most abundant fungal genera. The results revealed that the six samples could be grouped into two groups based on their province of origin. In the results of PCA and HCA analysis, the first three principal components which were chosen could explain 99.93% and 90.99% of the total bacterial and fungal communities, respectively.ConclusionThe results indicated high levels of bacteria and fungi in traditional Jiaozi and highlighted the possible influence of geographic areas on microbial diversity.

Investigation on the interaction between γ-cyclodextrin and α-amylase

A growing interest has been shown regarding the impact of α-amylase on the quality of fermented foods. Therefore, the interaction between γ-cyclodextrin and α-amylase was investigated in this article. The results showed that γ-cyclodextrin had an inhibitory effect on the activity of α-amylase under certain conditions, obtaining the strongest inhibitory effect when the concentration of γ-cyclodextrin was 10 mmol/L, the reaction temperature was 45 °C, pH = 5.9 and reaction time of 120 min. The results also showed important changes in the secondary structure of α-amylase induced by γ-cyclodextrin, including the transformation of α-helix, β-fold and random coil. Moreover, the addition of γ-cyclodextrin could induce the change of endogenous fluorescence intensity by changing the microenvironment of the α-amylase. According to the results of NMR, a part of the α-amylase molecule enters the cavity of the γ-cyclodextrin, and the other part forms a hydrogen bond with the outer cavity, forming a complex. The experimental results provide references for the application of γ-cyclodextrin and α-amylase.

Dynamic changes of bacterial communities and nitrite character during northeastern Chinese sauerkraut fermentation.

Northeastern Chinese sauerkraut is a well-known traditional fermented vegetable in China. Incomplete identification of the microorganisms' (bacteria in spontaneous fermentation) diversity and accumulation of nitrite make it difficult to normalize the fermentation process and product qualities of northeastern Chinese sauerkraut. Conventional culturing and polymerase chain reaction-denaturing gradient gel electrophoresis methods were combined to describe microbial structure and diversity. Lactobacillus, Leuconostoc, Enterobacter, Accumulibacter, Thermotoga, Pseudomonas, Clostridium, Rahnella and Citrobacter were predominant microorganisms in different fermentation periods. The pH value and nitrite concentration presentedacertainrelevancetothe amount of lacticacidbacteria. Lactobacillus and Leuconostoc had the ability to decrease nitrite by inhibiting nitrate-reducing bacteria such as Enterobacter. Therefore, Northeastern Chinese sauerkraut should not be eaten until 4weeks of fermentation for the safety and quality of fermented foods. Northeastern Chinese sauerkraut is rich in lacticacidbacteria, which demonstrate its ability as an excellent probiotic for applications in functional foods.