Free-amino acid profiles of thua nao, a Thai fermented soybean

The Potential Correlation between Bacterial Diversity and the Characteristic Volatile Flavor Compounds of Sichuan Sauce-Flavored Sausage

The distinctive taste of Sichuan sauce-flavored sausage comes from an intricate microbial metabolism. The correlation between microbial composition and distinct flavor components has not been researched. The study used headspace solid-phase microextraction action with gas chromatography mass spectrometry to find flavor components and high-throughput sequencing of 16S rRNA to look at the diversity and succession of microbial communities. The correlation network model forecasted the connection between essential bacteria and the development of flavors. The study revealed that the primary flavor compounds in Sichuan sauce-flavored sausages were alcohols, aldehydes, and esters. The closely related microbes were Leuconostoc, Pseudomonas, Psychrobacter, Flavobacterium, and Algoriella. The microbes aided in the production of various flavor compounds, such as 1-octen-3-ol, benzeneacetaldehyde, hexanal, (R,R)-2,3-butanediol, and ethyl caprylate. This work has enhanced our comprehension of the diverse functions that bacteria serve in flavor development during the fermentation of Sichuan sauce-flavored sausage.

Effect of tea polyphenol-trehalose complex coating solutions on physiological stress and flesh quality of marine-cultured Turbot Scophthalmus maximus during waterless transport

OBJECTIVE

The waterless transport of live fish has changed the present situation of live-fish transport. However, the waterless transport environment may cause stress in fish. This research evaluated the effect of tea polyphenol-trehalose (TPT) coating solutions on Turbot Scophthalmus maximus during waterless transport.

METHODS

After cold acclimation, Turbot were coated and subsequently transported in a waterless environment for 18 h. Physiological and biochemical parameters were measured, including lysozyme (LZM) and immunoglobulin M (IgM) activities, serum creatinine (Cr) and uric acid (UA) concentrations, and nutritional flavor.

RESULT

The results showed that the nonspecific immunity of Turbot was inhibited during the waterless transport; the LZM activity first increased and then decreased, and the serum Cr and UA concentrations significantly increased. In addition, the waterless transport promoted the breakdown of Turbot flesh proteins, leading to changes in nucleotides and free amino acids (FAAs). After waterless transport, the LZM and IgM activities in the TPT-treated Turbot were higher than those in the control group (CK), and the changes in FAA content and nucleotides were smaller than those observed in the CK group.

CONCLUSION

This study shows that the use of TPT coating solution can reduce the impact of waterless transportation stress on the immune and metabolic functions of Turbot and can maintain the meat quality and flavor of Turbot.

An Untargeted Metabolomics Approach to Study the Variation between Wild and Cultivated Soybeans

The differential metabolite profiles of four wild and ten cultivated soybeans genotypes were explored using an untargeted metabolomics approach. Ground soybean seed samples were extracted with methanol and water, and metabolic features were obtained using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) in both positive and negative ion modes. The UHPLC-HRMS analysis of the two different extracts resulted in the putative identification of 98 metabolites belonging to several classes of phytochemicals, including isoflavones, organic acids, lipids, sugars, amino acids, saponins, and other compounds. The metabolic profile was significantly impacted by the polarity of the extraction solvent. Multivariate analysis showed a clear difference between wild and cultivated soybean cultivars. Unsupervised and supervised learning algorithms were applied to mine the generated data and to pinpoint metabolites differentiating wild and cultivated soybeans. The key identified metabolites differentiating wild and cultivated soybeans were isoflavonoids, free amino acids, and fatty acids. Catechin analogs, cynaroside, hydroxylated unsaturated fatty acid derivatives, amino acid, and uridine diphosphate-N-acetylglucosamine were upregulated in the methanol extract of wild soybeans. In contrast, isoflavonoids and other minor compounds were downregulated in the same soybean extract. This metabolic information will benefit breeders and biotechnology professionals to develop value-added soybeans with improved quality traits.

The metabolome and bacterial composition of high-moisture Italian ryegrass silage inoculated with lactic acid bacteria during ensiling

BACKGROUND

With its high nutritional value and productivity, Italian ryegrass as a biomass feedstock constantly supplies rumen degradable nitrogen and digestible fiber to ruminants. However, biofuel production is easily reduced during ensiling due to the high-moisture content of Italian ryegrass, leading to economic losses. Lactic acid bacteria inoculants could improve lignocellulosic degradation and fermentation quality and decrease dry matter loss during the bioprocessing of silage. Therefore, this study analyzed the effects of Lactobacillus buchneri TSy1-3 (HE), Lactobacillus rhamnosus BDy3-10 (HO), and the combination of HE and HO (M) on fermentation quality, bacterial community and metabolome in high-moisture Italian ryegrass silage during ensiling.

RESULTS

The results showed that the pH value was significantly lower in the HO groups than in the other treatments at the end of ensiling, and the dry matter and acetic acid contents were significantly higher in the HO group than in the other inoculated groups. All inoculants decreased the diversity of the bacterial community and significantly increased the relative abundance of Lactobacillus. Inoculation with HO significantly improved the concentrations of organic acids, dipeptides, ferulic acid, apigenin, and laricitrin. Compared with Lactobacillus buchneri TSy1-3 (HE), HO significantly upregulated the flavonoid compounds in the flavone and flavonol biosynthesis pathway.

CONCLUSIONS

Overall, these findings suggest that inoculation with HO was beneficial for the development of Italian ryegrass as a biomass feedstock, improving fermentation quality, accelerating changes in bacterial community composition and increasing biofunctional metabolites in high-moisture Italian ryegrass silage.

Sensory and physicochemical properties of biscuit produced from blends of whole wheat, soy okara and tigernut residue flours

Biscuits are popular ready to eat, cheap and convenient food products that are consumed globally. Supplementation of wheat flour with inexpensive staples from other cereals, legumes, roots and tubers will help in improving the nutritional quality of wheat products. Therefore, this study investigated the sensory and physicochemical properties of biscuits produced from blends of whole wheat, soy okara and tigernut residue flours. The sensory qualities of the twelve whole wheat, soy okara and tigernut residue flour biscuits at p < 0.05 ranged from 5.36 to 7.68 (color), 5.60-7.64 (appearance), 4.48-7.96 (mouthfeel), 4.28-7.76 (aroma), 3.96-8.32 (taste), 3.64-8.20 (crunchiness), 3.56-7.56 (crispiness), and 5.08-8.36 (overall acceptability). Physical, proximate and mineral analysis were carried out on the best five biscuit samples containing 100:0:0 (MVP), 60:20.98:19.02 (ISP), 50.75:39.25:10 (JAR), 53.79:22.57:23.64 (GEN) and 56.32:27.39:16.29 (XEC) whole wheat, soy okara and tigernut residue flours respectively. The physical analysis showed that diameter (38.13-38.17 mm), height (37.73-37.76 mm) and thickness (6.10-6.17 mm) were not significantly different, but the weight (7.30-7.73 g), spread ratio (5.73-6.10 mm) and breaking strength (600-643 g) significantly (p < 0.05) differed among the biscuit samples. The proximate composition of the biscuits ranged from; ash (1.70-1.90%), moisture (4.00-5.70%), fiber (7.00-11.30%), fat (16.20-17.30%), protein (6.50-12.00%), carbohydrate (56.94-59.20%) while mineral content ranged from; magnesium (122.00-134.00 mg/100 g), sodium (16.00-28.00 mg/100 g), calcium (12.00-24.00 mg/100 g), iron (2.30-3.50 mg/100 g) and phosphorus (100.00-121.00 mg/100 g). The study showed that substitution of wheat flour with soy okara and tigernut residue flour at a ratio of 60:20.98:19.02 yielded the most acceptable biscuits in all the sensory attributes assessed. This implies that biscuits produced from this composite blend contain sufficient amounts of protein, fat, fiber and carbohydrate. Hence, they can serve as relief for malnutrition.

Bacterial Communities in Lanna Fermented Soybeans from Three Different Ethnolinguistic Groups in Northern Thailand

Northern Thailand, the main part of the Lanna region, is home to a diverse range of ethnic groups, each with their own food and cultural heritage. The bacterial compositions in fermented soybean (FSB) products indigenous to three Lanna ethnolinguistic groups, including Karen, Lawa, and Shan, were investigated in this study. Bacterial DNA was extracted from the FSB samples and subjected to 16S rRNA gene sequencing using the Illumina sequencing platform. Metagenomic data showed that the predominant bacteria in all FSBs were members of the genus Bacillus (49.5-86.8%), and the Lawa FSB had the greatest bacterial diversity. The presence of genera Ignatzschineria, Yaniella, Atopostipes in the Karen and Lawa FSBs and Proteus in the Shan FSB might be indicators of food hygiene problems during processing. The network analysis predicted antagonistic effects of Bacillus against some indicator and pathogenic bacteria. The functional prediction revealed some potential functional properties of these FSBs. The presence of Bacillus in all FSBs and Vagococcus in the Shan FSB suggests that these FSBs could potentially be good sources of beneficial bacteria, and they should be conserved and promoted for health and food security reasons. However, food processing hygiene measures should be introduced and monitored to warrant their properties as health foods.

Chemical composition of kabuli and desi chickpea (Cicer arietinum L.) cultivars grown in Xinjiang, China

Chickpeas are a very important legume crop and have abundant protein, carbohydrate, lipid, fiber, isoflavone, and mineral contents. The chemical compositions of the four chickpea species (Muying-1, Keying-1, Desi-1, Desi-2) from Xinjiang, China, were analyzed, and 46 different flavonoids in Muying-1 were detected. The moisture content ranged from 7.64 ± 0.01 to 7.89 ± 0.02 g/100 g, the content of starch in the kabuli chickpeas was greater than that in the desi chickpeas, the total ash content ranged from 2.59 ± 0.05 to 2.69 ± 0.03 g/100 g and the vitamin B₁ content of the chickpeas ranged from 0.31 to 0.36 mg/100 g. The lipid content ranged from 6.35 to 9.35 g/100 g and the major fatty acids of chickpeas were linoleic, oleic, and palmitic acids. Both kabuli and desi chickpeas have a high content of unsaturated fatty acids (USFAs), Muying-1 and Desi-1 contained the highest level of linoleic acid, and Keying-1 had the highest oleic acid content. The protein level ranged from 19.79 ± 2.89 to 23.38 ± 0.30 g/100 g, and the main amino acids were aspartic acid, glutamic acid, and arginine acid. The four chickpea species had significant amounts of essential amino acids (EAAs). Forty-six varieties of flavonoids in Muying-1 were determined by ultra high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-QqQ-MS) analysis, and there were higher levels of conjugate flavonoids (55.95%) than free flavonoids (44.05%). Isoflavones were the most abundant flavonoids in Muying-1, and among the isoflavones, daidzin had the highest content, followed by biochanin A and genistin. Muying-1 was rich in daidzin, biochanin A, genistin, troxerutin, isorhamnetin, astilbin, L-epicatechin, astragalin, acacetin, hyperoside, and myricitrin. Information provided in the study will be helpful to further understand the chemical composition of chickpeas and be beneficial to the development of chickpeas.

Enrichment of taste and aroma perceptions in chicken meat stewed in braised soup used repeatedly

Flavor enrichment of sauce-braised chicken creates a popular umami taste and aroma. In order to preliminarily reveal the enrichment of taste and aroma compounds of sauce-braised meat products processed with braised soup used repeatedly, the system containing only chicken and chicken soup was designed to simulate the process of repeated stewing. Free amino acids, 5-nucleotides, fatty acids, and volatile compounds in stewed chicken were determined, and taste and aroma profiles were evaluated using an electronic tongue (E-tongue) and an electronic nose (E-nose), respectively. As repeated stewing times increased, the total free amino acid content increased from 514.37 mg/100 g to 721.33 mg/100 g, and the contents of 5'-inosine monophosphate, 5'-guanosine monophosphate, and 5'-adenosine monophosphate increased by approximately 20%. Meanwhile, the relative content of saturated fatty acids increased, and the relative content of monounsaturated fatty acids decreased significantly. Oleic acid, linoleic acid, and palmitoleic acid accounted for more than 80% of the total fatty acid content. A total of 15 aroma-active compounds were identified during repeated stewing, and their concentrations increased by more than 40%, especially for monounsaturated alkenals. Within 10 times of repeated stewing, the taste and aroma compounds were enriched because of a decrease in the concentration difference of taste substances and an increase in the flavor-adsorption capacity of fat, which was also consistent with the results from the E-nose and E-tongue. The taste and aroma of stewed chicken tended to remain constant after 10 times of repeated stewing of braised soup. The obtained information can provide guidelines for regulating the aroma and taste of sauce-braised chicken. PRACTICAL APPLICATION: The fat level of stewed chicken and the difference in concentration between stewed meat and braised soup were important potential factors that could be employed to enhance the flavor of stewed meat.

Recent trends in microbial flavour Compounds: A review on Chemistry, synthesis mechanism and their application in food

Aroma and flavour represent the key components of food that improves the organoleptic characteristics of food and enhances the acceptability of food to consumers. Commercial manufacturing of aromatic and flavouring compounds is from the industry's microbial source, but since time immemorial, its concept has been behind human practices. The interest in microbial flavour compounds has developed in the past several decades because of its sustainable way to supply natural additives for the food processing sector. There are also numerous health benefits from microbial bioprocess products, ranging from antibiotics to fermented functional foods. This review discusses recent developments and advancements in many microbial aromatic and flavouring compounds, their biosynthesis and production by diverse types of microorganisms, their use in the food industry, and a brief overview of their health benefits for customers.

Integrated Microbiomic and Metabolomic Dynamics of Fermented Corn and Soybean By-Product Mixed Substrate

Microbes and their metabolites produced in fermented food have been considered as critical contributors to the quality of the final products, but the comprehensive understanding of the microbiomic and metabolomic dynamics in plant-based food during solid-state fermentation remains unclear. Here, the probiotics of Bacillus subtilis and Enterococcus faecalis were inoculated into corn and defatted soybean to achieve the two-stage solid-state fermentation. A 16S sequencing and liquid chromatography–tandem mass spectrometry were applied to investigate the dynamics of microbiota, metabolites, and their integrated correlations during fermentation. The results showed that the predominant bacteria changed from Streptophyta and Rickettsiales at 0 h to Bacillus and Pseudomonas in aerobic stage and then to Bacillus, Enterococcus, and Pseudomonas in anaerobic stage. In total, 229 notably different metabolites were identified at different fermentation times, and protein degradation, amino acid synthesis, and carbohydrate metabolism were the main metabolic pathways during the fermentation. Notably, phenylalanine metabolism was the most important metabolic pathway in the fermentation process. Further analysis of the correlations among the microbiota, metabolites, and physicochemical characteristics indicated that Bacillus spp. was significantly correlated with amino acids and carbohydrate metabolism in aerobic stage, and Enterococcus spp. was remarkably associated with amino acids metabolism and lactic acid production in the anaerobic stage. The present study provides new insights into the dynamic changes in the metabolism underlying the metabolic and microbial profiles at different fermentation stages, and are expected to be useful for future studies on the quality of fermented plant-based food.

Effect of Gum Tragacanth-Sodium Alginate Active Coatings Incorporated With Epigallocatechin Gallate and Lysozyme on the Quality of Large Yellow Croaker at Superchilling Condition

This research was done to investigate the synergistic interactions of the gum tragacanth (GT)–sodium alginate (SA) active coatings, incorporated with epigallocatechin gallate and lysozyme, on the quality of large yellow croaker (Larimichthys crocea) during superchilling storage at −3°C. Results showed that the GT-SA active coatings, containing epigallocatechin gallate [EGCG (E), 0.32% w/v], and lysozyme [LYS (L), 0.32% w/v] have reduced the total viable count, psychrophilic bacteria, and Pseudomonas spp. by about 1.55 log CFU/g, 0.49 log CFU/g, and 1.64 log CFU/g compared to the control at day 35. The GT-SA active coatings containing EGCG and LYS were effective in lowering the formations of off-odor compounds such as total volatile basic nitrogen (TVB-N), malondialdehyde (MDA), and off-favor amino acid (histidine). The solid phase microextraction gas chromatography-mass spectrometer (SPME-GC/MS) was applied to characterize and to quantify the volatile compounds of large yellow croaker samples during superchilling storage, while the relative content of the fishy flavor compounds (including 1-octen-3-ol and acetoin) was significantly reduced in the active coatings treated samples. Furthermore, the GT-SA active coatings containing EGCG and LYS treatments was found to be more effective in retarding the migration of water based on magnetic resonance imaging (MRI) results and in maintaining the organoleptic quality of large yellow croaker in superchilling storage at −3°C according to the sensory evaluation results. The results showed that the GT-SA active coating containing EGCG and LYS was effective to be used as a fish preservative to improve the quality and to prolong the shelf life of large yellow croaker in a superchilling storage for at least 7 days.

Shotgun sequence-based metataxonomic and predictive functional profiles of Pe poke, a naturally fermented soybean food of Myanmar

Pe poke is a naturally fermented sticky soybean food of Myanmar. The present study was aimed to profile the whole microbial community structure and their predictive gene functionality of pe poke samples prepared in different fermentation periods viz. 3 day (3ds), 4 days (4ds), 5 days (5ds) and sun-dried sample (Sds). The pH of samples was 7.6 to 8.7, microbial load was 2.1-3.9 x 108 cfu/g with dynamic viscosity of 4.0±1.0 to 8.0±1.0cP. Metataxonomic profile of pe poke samples showed different domains viz. bacteria (99.08%), viruses (0.65%), eukaryota (0.08%), archaea (0.03%) and unclassified sequences (0.16%). Firmicutes (63.78%) was the most abundant phylum followed by Proteobacteria (29.54%) and Bacteroidetes (5.44%). Bacillus thermoamylovorans was significantly abundant in 3ds and 4ds (p<0.05); Ignatzschineria larvae was significantly abundant in 5ds (p<0.05), whereas, Bacillus subtilis was significantly abundant in Sds (p <0.05). A total of 172 species of Bacillus was detected. In minor abundance, the existence of bacteriophages, archaea, and eukaryotes were also detected. Alpha diversity analysis showed the highest Simpson's diversity index in Sds comparable to other samples. Similarly, a non-parametric Shannon's diversity index was also highest in Sds. Good's coverage of 0.99 was observed in all samples. Beta diversity analysis using PCoA showed no significant clustering. Several species were shared between samples and many species were unique to each sample. In KEGG database, a total number of 33 super-pathways and 173 metabolic sub-pathways were annotated from the metagenomic Open Reading Frames. Predictive functional features of pe poke metagenome revealed the genes for the synthesis and metabolism of wide range of bioactive compounds including various essential amino acids, different vitamins, and enzymes. Spearman's correlation was inferred between the abundant species and functional features.

Enhanced flavor strength of broth prepared from chicken following short-term frozen storage

This study investigated the effect of frozen storage periods (0, 2, 4, 6, or 8 weeks) of raw meat and stewing on the flavor of chicken broth. With the increased storage duration of frozen raw material, the contents of the free amino acids, nucleotides and mineral elements in the broth decreased significantly, especially within the first 4 weeks, and then increased significantly. Meanwhile, the volatile compounds showed the reverse trend. The results from the E-nose, E-tongue and sensory evaluation indicated a progressive difference in overall flavor profiles between the samples. The sensory scores of the meaty and fatty traits reached a maximum as raw chicken meat was stored for 4 weeks at -18 °C, which should be related to the increased contents of aldehydes and 2-pentyl furan. Overall, the limited storage duration of frozen raw meat can enhance the flavor of chicken broth.

Processed by-Products from Soy Beverage (Okara) as Sustainable Ingredients for Nile Tilapia (O. Niloticus) Juveniles: Effects on Nutrient Utilization and Muscle Quality

Simple Summary

The consumption of soy products increases worldwide and generates large amounts of by-products, which are often discarded. Okara is a soybean by-product with high nutritional value. This work evidenced the great potential of okara meal, after appropriate technological processing, to be used as feed ingredient in Nile tilapia diets. It was clearly demonstrated the effectiveness of the autoclave and the use of proteases from C. cardunculus without fermentation to increase okara nutrient bioavailability. The inclusion of up to 20% okara meal in diets for tilapia did not affect growth performance, nutrient utilization, or whole body composition compared to a reference diet. Flesh quality remained largely unaffected, although fish fed with AOK diets had the highest density of muscle fibers.

Abstract

The apparent digestibility coefficients (ADCs) of differently processed okara meals were assessed in Nile tilapia diets: dried okara not autoclaved (FOK), dried okara autoclaved (AOK), okara hydrolyzed with Alcalase (ALOK) or Cynara cardunculus proteases (CYOK), and hydrolyzed okara fermented with lactic bacteria: Lactobacillus rhamnosus R11 (CYR11OK) or Bifidobacterium animalis ssp. lactis Bb12 (CYB12OK). Okara processing significantly affected nutrient digestibility: dry matter ADC was highest in CYR11OK (80%) and lowest in FOK (40%). The lowest protein digestibility was observed in CYR11OK (72%), and the highest in AOK (97%) and CYOK (91%), evidencing the effectiveness of the autoclave and the use of C. cardunculus proteases to increase okara protein bioavailability. The inclusion of up to 20% of AOK or CYOK did not affect fish growth, nutrient utilization, or whole body composition of Nile tilapia. The flesh quality (color, pH, water activity, cohesiveness, elasticity and resilience) was not affected by the dietary incorporation of AOK or CYOK. Fish fed with AOK diets stand out for their high density of muscle fibers, particularly in AOK20, which can explain their high muscle firmness and may result in further hypertrophic growth. Altogether, results suggest that hydrolyzed or autoclaved okara are valuable ingredients for Nile tilapia diets.

Bacterial and fungal communities and their predictive functional profiles in kinema, a naturally fermented soybean food of India, Nepal and Bhutan

Bacterial and fungal communities in kinema, a naturally fermented soybean food of the Eastern Himalayan regions of India, Nepal and Bhutan were profiled by high-throughout sequence analysis. Firmicutes (78.4%) was the most abundant phylum in kinema, followed by Proteobacteria (14.76%) and other phyla. Twenty seven species of Bacillus were detected, among which Bacillus subtilis (28.70%) was the most abundant bacterium, followed by B. licheniformis, B. thermoamylovorans, B. cereus, Ignatzschineria larvae, Corynebacterium casei, B. sonorensis, Proteus vulgaris, Brevibacillus borstelensis, Thermoactinomyces vulgaris, Lactobacillus fermentum and Ignatzschineria indica. Ascomycota was the most abundant fungal phylum in kinema. Wallemia canadensis, Penicillium spp., Aspergillus spp., Exobasidium spp., Arthrocladium spp., Aspergillus penicillioides, Mortierella spp., Rhizopus arrhizus and Mucor circinelloides, were major moulds, and Pichia sporocuriosa, Trichosporon spp., Saccharomycopsis malanga and Rhodotorula cycloclastica were abundant yeasts in kinema. We detected 277 species of bacteria among which, 99.09% were culturable and 0.91% were unculturable; and 80 fungal species among which, 33.72% were culturable and 66.28% were unculturable. Several unique bacterial genera to each country were observed, whereas no unique fungal genus was observed in kinema. Maximum coverage of sequencing depth was observed in all samples. Based on PCA plot, close relation was observed between samples of India and Nepal, whereas samples of Bhutan was clearly distinctive. Predictive functional features of bacterial and fungi related to metabolisms were inferred by the KEGG Orthology and MetaCyc databases, respectively.

Multifunctional properties and safety evaluation of lactic acid bacteria and yeasts associated with fermented cereal doughs

Spontaneous cereal fermentations involve diverse lactic acid bacteria (LAB) and yeasts which may include multifunctional and safe or unsafe strains. This study assessed acidification ability, safety, antifungal activity and free amino acids release ability of LAB and yeasts previously isolated from spontaneously fermented cereal doughs in Benin. Fourteen LAB and thirteen yeast strains were studied in liquid media and/or in a model cereal dough prepared in laboratory conditions. Antifungal activity was assessed against Candida glabrata in liquid medium. Amino acids were determined by pre-column derivatization and separation with reversed-phase HPLC. Antimicrobial susceptibility was analysed by minimum inhibitory concentration determination. The acidification ability was higher for LAB compared to yeast strains. All LAB strains retarded the growth of C. glabrata Cg1 with the highest inhibition recorded for Weissella confusa Wc1 and Wc2. The highest free amino acid content was found in the doughs fermented with Pichia kudriavzevii Pk2 and Pk3. All the LAB strains were susceptible to ampicillin, chloramphenicol, erythromycin, but displayed phenotypic resistance to kanamycin, streptomycin and tetracycline. Positive PCR amplicon of resistance genes were detected in the following cases: 2 LAB strains were positive for kanamycin (aph(3)III), 5 strains were positive for streptomycin (aadA and/or strA and/or strB) and 3 strains were positive for tetracycline (tet (L) and/or tet (M)). For yeasts, most of the P. kudriavzevii strains were resistant to amphotericin B, fluconazole and itraconazole opposite to K. marxianus and Saccharomyces cerevisiae strains which were susceptible. The results obtained are valuable for selecting safe and multifunctional strains for cereal fermentation in West Africa.

Metatranscriptome-based investigation of flavor-producing core microbiota in different fermentation stages of dajiang, a traditional fermented soybean paste of Northeast China

Dajiang, or naturally fermented soybean paste, has a unique flavor that is influenced by the resident microflora. However, the association between flavor and the core microbiota is unclear. Recent advances in RNA sequencing have identified genes that are actively expressed in complex microbial communities. To this end, we analyzed the time-dependent changes in the microbiota and the metabolite profiles of Dajiang using metatranscriptome sequencing, HS-SPME-GC-MS and amino acid analysis identified 10 volatile compounds that contribute to the development of soybean paste flavor. Further analysis of the correlation between the active microorganisms and the physicochemical characteristics and flavor substances in soybean paste indicated that Lactobacillus and Tetragenococcus were the core genera affecting chromaticity and flavor. These microorganisms produce enzymes that catalyze a series of metabolic pathways that generate flavor substances. Our findings provide new insights into the role of the microbiota in the development of flavor in fermented foods.

Comparative metagenomics and characterization of antimicrobial resistance genes in pasteurized and homemade fermented Arabian laban

The aim of this study was to investigate bacterial diversity and function in a fermented milk drink called laban, which is traditionally served in the Middle East, Africa, and Indian subcontinent. Pasteurized laban (LBP) and unpasteurized, homemade, raw laban (LBR) underwent 16S rRNA gene amplicon and shotgun sequencing to analyze their bacterial community, presence of antimicrobial resistance genes (ARGs), and metabolic pathways. This study highlighted relatively greater diversity in LBR bacterial populations compared to LBP, despite containing similar major taxa that consisted primarily of Firmicutes followed by Proteobacteria, Bacteroidetes, and Actinobacteria. The dominant species, Streptococcus thermophilus, was relatively more abundant in LBP (80.7%) compared to LBR (47.9%). LBR had increased diversity and higher relative abundance of several known probiotic bacteria, such as Streptococcus salivarius and Lactococcus lactis, whereas Lactobacillus acidophilus was detected at a higher abundance in LBP. Pathogens like Acinetobacter baumannii, Streptococcus pneumoniae, Streptococcus pyogenes, and Escherichia coli had lower abundance in LBP compared to LBR. Thirty-three ARGs were detected in LBR compared to nine in LBP and are responsible for resistance to 11 classes of antibiotics. A significant proportion of the metagenomes from both types of laban were assigned to housekeeping functions, such as amino acid metabolism, translation, membrane transport, and carbohydrate metabolism. LBR demonstrated increased diversity in probiotics and metabolic functions compared to LBP. However, the relatively high diversity of pathogenic and opportunistic bacteria and ARGs in LBR raises safety concerns and highlights the need for a more hygienic environment for the processing of homemade fermented dairy foods.

Structural Characterization of Functional Ingredient Levan Synthesized by Bacillus siamensis Isolated from Traditional Fermented Food in Thailand

The rising global population continues to threaten the world’s food security. The discovery of new technologies to produce food of nutritional and functional properties is urgently needed. One beneficial food to humans of known nutritional value is the prebiotic levan. To address the problem, the present work is aimed at isolating levansucrase enzyme-producing microorganisms from traditional fermented food in Thailand. Bacterial colony morphology was observed for mucoidal consistency on culture plates. Isolated colonies were characterized morphologically by gram staining methods. Dinitrosalicylic acid (DNS) and thin-layer chromatography (TLC) reported the highest microbial enzyme activity of 8.51 IU/ml at 12 hours via hydrolysis and frutotransferase activities. Structural characterization of levan via Fourier-transform infrared spectroscopy (FTIR) and 1H and 13C nuclear magnetic resonance (NMR) spectroscopy showed β-(2,6)-fructofuranose linkages. The highest enzyme activity was exhibited by bacterium B-6 identified as Bacillus siamensis NR 11274.1 based on the 16s rDNA gene sequence analyses. Thus, the isolated bacterium from the traditional food was confirmed to produce levansucrase enzyme of high industrial importance for the synthesis of levan as a functional food.

Bacillus amyloliquefaciens RWL-1 as a New Potential Strain for Augmenting Biochemical and Nutritional Composition of Fermented Soybean

Soybean (Glycine max L.) is a good source of natural antioxidants and commonly consumed as fermented products such as cheonggukjang, miso, tempeh, and sufu in Asian countries. The aim of the current study was to examine the influence of novel endophytic bacterial strain, Bacillus amyloliquefaciens RWL-1 as a starter for soybean fermentation. During fermentation, the cooked soybeans were inoculated with different concentrations (1%, 3%, and 5%) of B. amyloliquefaciens RWL-1. The changes in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, total phenolic contents, isoflavones (Daidzin, Genistin, Glycitin, Daidzein, Glycitein, and Genistein), amino acids (aspartic acid, threonine, serine, glutamic acid, glycine, alanine, cysteine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine, arginine, and proline) composition, and minerals (calcium, copper, iron, potassium, magnesium, manganese, sodium, nickel, lead, arsenic, and zinc) were investigated. The level of antioxidants, total phenolic contents, isoflavones, and total amino acids were higher in fermented soybean inoculated with 1% B. amyloliquefaciens RWL-1 after 60 h of fermentation as compared to control, 3% and 5% B. amyloliquefaciens RWL-1. Additionally, fermented soybean inoculated with 5% B. amyloliquefaciens RWL-1 showed the highest values for mineral contents. Changes in antioxidant activities and bioactive compounds depended on the concentration of the strain used for fermentation. From these results, we conclude that fermented soybean has strong antioxidant activity, probably due to its increased total phenolic contents and aglycone isoflavone that resulted from fermentation. Such natural antioxidants could be used in drug and food industries and can be considered to alleviate oxidative stress.

Effect of microwave sterilization on maturation time and quality of low-salt sufu

The objective of this study was to reduce the microorganism number and salt content in pehtze by microwave sterilization. The maturation time and quality of low-salt sufu were evaluated. The microorganism inactivation rate, moisture content and water activity of the pehtze, which was used for the growth of the starter culture, showed that 4,250 W for 30 s was suitable for the preparation of low-salt sufu. With regard to the physicochemical properties of sufu, 120-day sufu samples obtained by traditional high-salt (14%) fermentation and 75-day sufu samples obtained by low-salt (4%) fermentation met the standard requirements. With regard to the sensory characteristics of sufu, the taste and after taste scores of 75-day low-salt sufu samples were significantly higher than those of 120-day high-salt sufu samples (p < .05).The overall acceptance score of low-salt sufu samples also was higher than that of high-salt sufu samples. The contents of free amino acids and the profiles of typical flavor compounds partly explained the sensory quality and shorter ripening time of sufu manufactured. The total biogenic amine contents were reduced by 46%.

Meta-omics reveal microbial assortments and key enzymes in bean sauce mash, a traditional fermented soybean product

BACKGROUND

Dajiang is fermented based on the metabolism of microbial communities in bean sauce mash, a traditional fermented soybean product in China. The current study first investigated the metaproteome of bean sauce mash. This was followed by an analysis of its biological functions and its microbial community to reveal information about strains and about the expressed proteins to better understand the roles of the microbiota in bean sauce mash.

RESULTS

The metaproteomic results demonstrated that a total of 1415 microbial protein clusters were expressed mainly by members of the Penicillium and Rhizopus genera and were classified into 100 cellular components, 238 biological processes, and 220 molecular function categories by gene ontology (GO) annotation. Enzymes associated with glycolysis metabolic pathways were also identified. These can provide the energy required for microbial fermentation. Illumina MiSeq sequencing technology results showed that the microorganism communities of bean sauce mash exhibited a high level of diversity. Microbiological analysis demonstrated that the Penicillium, Mucor, Fusarium, Aspergillus, and Rhizopus fungi, and Lactobacillus, Enterococcus, Fructobacillus, Staphylococcus, Carnobacterium genera were predominant 22 samples.

CONCLUSION

The profiles and insights in the current study are important for research on bean sauce mash and related products in terms of their food microbial ecology. The information obtained from this study will help the development of stable sufu starter cultures with unique sensory qualities. © 2019 Society of Chemical Industry.

Metagenomic Insights Into the Taxonomic and Functional Features of Kinema, a Traditional Fermented Soybean Product of Sikkim Himalaya

Kinema is an ethnic, naturally fermented soybean product consumed in the Sikkim Himalayan region of India. In the present study, the whole metagenome sequencing approach was adopted to examine the microbial diversity and related functional potential of Kinema, consumed in different seasons. Firmicutes was the abundant phylum in Kinema, ranging from 82.31 to 93.99% in different seasons, followed by Actinobacteria and Proteobacteria. At the species level, the prevalent microorganisms were Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus licheniformis, Corynebacterium glutamicum, Bacillus pumilus, and Lactococcus lactis. The abundance of microbial species varied significantly in different seasons. Further, the genomic presence of some undesirable microbes like Bacillus cereus, Proteus mirabilis, Staphylococcus aureus, Proteus penneri, Enterococcus faecalis, and Staphylococcus saprophyticus, were also detected in the specific season. The metagenomic analysis also revealed the existence of bacteriophages belonging to the family Siphoviridae, Myoviridae, and Podoviridae. Examination of the metabolic potential of the Kinema metagenome depicted information about the biocatalysts, presumably involved in the transformation of protein and carbohydrate polymers into bioactive molecules of health-beneficial effects. The genomic resource of several desirable enzymes was identified, such as β-galactosidase, β-glucosidase, β-xylosidase, and glutamate decarboxylase, etc. The catalytic function of a novel glutamate decarboxylase gene was validated for the biosynthesis of γ-aminobutyric acid (GABA). The results of the present study highlight the microbial and genomic resources associated with Kinema, and its importance in functional food industry.

Proteomic study of bioactive peptides from tempe

Tempe is a traditional Indonesian fermented soybean mostly produced in small industries and sold locally throughout the country. Studies on the bioactive peptides in tempe are rare. Here, we studied bioactive peptides in samples from three tempe producers with different degrees of sanitation. The peptide sub-fractions of tempe from each producer were collected following water extraction, ultrafiltration (<3 kDa), gel filtration chromatography, and reversed phase-high performance liquid chromatography (RP-HPLC) separation followed by liquid chromatography-mass spectrometry (LC-MS). The MS spectra were then predicted using FindPept tools, and their biofunctionalities were confirmed with BIOPEP databases. There were few similar peptides found in tempe from the three producers. Peptides Val-His and Ala-Leu-Glu-Pro were found in tempe from all producers. Producers having a good sanitation level had more bioactive peptides than those with moderate or poor sanitation levels (58%, 43% and 35%, from good to poor sanitation). This work showed that the tempe from the three producers had antihypertensive, antidiabetic, antioxidative and antitumor peptides.

Quality Ingredients and Safety Concerns for Traditional Fermented Foods and Beverages from Asia: A Review

Fermented foods and beverages serve as vehicles for beneficial microorganisms that play an important role in human health and remain the oldest prevalent means of food processing and preservation. Traditional fermented foods are popular in Asia for their nutritional balance and food security. Techniques for preserving cereals, vegetables, and meat products are well developed in many Asian countries. Due to their cultural and nutritional significance, many of these foods have been studied in detail and their quality and safety have also been improved. These fermented foods and beverages provide benefits through enhanced nutritional content, digestibility, microbial stability, and detoxification. They represent is thus one of the most affordable and suitable methods to maintain hygiene condition and food quality and security in poor and underdeveloped countries. There is an industrial interest and scope related to traditional fermented foods and beverages in Asia. However, urgent attention is required to improve the quality of the ingredients and the integration of food safety management systems for industrial growth.

Characteristic Flavor of Traditional Soup Made by Stewing Chinese Yellow-Feather Chickens

The traditional recipe for Chinese chicken soup creates a popular taste of particular umami and aroma. The present study investigated the effects of stewing time (1, 2, and 3 h) on the principal taste-active and volatile compounds and the overall flavor profile of traditional Chinese chicken soup by measuring the contents of free amino acids (FAAs), 5'-nucleotides, minerals and volatile compounds and by evaluating the taste and aroma profiles using an electronic nose, an electronic tongue and a human panel. Results showed that the major umami-related compounds in the chicken soup were inosine 5'-monophosphate (IMP) and chloride, both of which increased significantly (P < 0.05) during stewing. The taste active values (TAVs) of the equivalent umami concentration (EUC) increased from 4.08 to 9.93 (P < 0.05) after stewing for 3 h. Although the FAA and mineral contents increased significantly (P < 0.05), their TAVs were less than 1. The volatile compounds were mainly hexanal, heptanal, octanal, nonanal, (E)-2-nonanal, (E)-2-decenal, (E,E)-2,4-decadienal, 1-hexanol, and 2-pentyl furan. With the prolonged stewing time, the aldehydes first increased and then decreased significantly (P < 0.05), while 1-hexanol and 2-pentyl furan increased steadily (P < 0.05). The aroma scores of the chicken soup reached the maximum after stewing for 3 h. The discrepancy in overall flavor characteristics tended to stabilize after 2 h of stewing. In general, stewing time has a positive effect on improving the flavor profiles of chicken soup, especially within the first 2 h.

Functional Properties of Microorganisms in Fermented Foods

Fermented foods have unique functional properties imparting some health benefits to consumers due to presence of functional microorganisms, which possess probiotics properties, antimicrobial, antioxidant, peptide production, etc. Health benefits of some global fermented foods are synthesis of nutrients, prevention of cardiovascular disease, prevention of cancer, gastrointestinal disorders, allergic reactions, diabetes, among others. The present paper is aimed to review the information on some functional properties of the microorganisms associated with fermented foods and beverages, and their health-promoting benefits to consumers.

Review: Diversity of Microorganisms in Global Fermented Foods and Beverages

Culturalable and non-culturable microorganisms naturally ferment majority of global fermented foods and beverages. Traditional food fermentation represents an extremely valuable cultural heritage in most regions, and harbors a huge genetic potential of valuable but hitherto undiscovered strains. Holistic approaches for identification and complete profiling of both culturalable and non-culturable microorganisms in global fermented foods are of interest to food microbiologists. The application of culture-independent technique has thrown new light on the diversity of a number of hitherto unknown and non-cultural microorganisms in naturally fermented foods. Functional bacterial groups ("phylotypes") may be reflected by their mRNA expression in a particular substrate and not by mere DNA-level detection. An attempt has been made to review the microbiology of some fermented foods and alcoholic beverages of the world.

Evaluation of autochthonous micrococcus strains as starter cultures for the production of Kedong sufu

AIMS

The technological properties of 22 micrococcus strains from traditional fermented Kedong sufu were evaluated in order to develop autochthonous starter cultures.

METHODS AND RESULTS

The proteolytic, autolytic and lipolytic activity, salt tolerance, production and degradation of the biogenic amines of six Micrococcus luteus, nine Kocuria kristinae and seven Kocuria rosea were evaluated. The results indicated that these micrococcus strains exhibited a certain technological diversity, and the results also indicated the best properties to be used in mixed starter cultures. Based on the above findings, two sets of autochthonous starters were formulated. Considering the physicochemical properties and sensory characteristics of sufu, the maturation period of sufu was shortened by 30 days. The profiles of free amino acids and peptides partly revealed the mechanism of sensory quality and shorter ripening time of sufu manufactured using autochthonous mixed starters. Compared to back-slopping fermentation, sufu manufactured with selected autochthonous starter cultures exhibited lower levels of total biogenic amines.

CONCLUSIONS

The selected strains could be used as starter to avoid the accumulation of high concentrations of biogenic amines while also maintaining typical sensory characteristics and preserving the autochthonous strains of the traditional Kedong sufu. The maturation times of Kedong sufu were shortened by 30 days with application of the autochthonous starter.

SIGNIFICANCE AND IMPACT OF THE STUDY

Autochthonous mixed starters can reduce the generation of biogenic amines, speed up the sufu maturation process and preserve typical sensory quality. Furthermore, the rotation of two sets of mixed starter cultures can effectively resist phage attack during the production of sufu.

Identification of key micro-organisms involved in Douchi fermentation by statistical analysis and their use in an experimental fermentation

AIMS

To screen and identify safe micro-organisms used during Douchi fermentation, and verify the feasibility of producing high-quality Douchi using these identified micro-organisms.

METHODS AND RESULTS

PCR-denaturing gradient gel electrophoresis (DGGE) and automatic amino-acid analyser were used to investigate the microbial diversity and free amino acids (FAAs) content of 10 commercial Douchi samples. The correlations between microbial communities and FAAs were analysed by statistical analysis. Ten strains with significant positive correlation were identified. Then an experiment on Douchi fermentation by identified strains was carried out, and the nutritional composition in Douchi was analysed. Results showed that FAAs and relative content of isoflavone aglycones in verification Douchi samples were generally higher than those in commercial Douchi samples.

CONCLUSIONS

Our study indicated that fungi, yeasts, Bacillus and lactic acid bacteria were the key players in Douchi fermentation, and with identified probiotic micro-organisms participating in fermentation, a higher quality Douchi product was produced.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report to analyse and confirm the key micro-organisms during Douchi fermentation by statistical analysis. This work proves fermentation micro-organisms to be the key influencing factor of Douchi quality, and demonstrates the feasibility of fermenting Douchi using identified starter micro-organisms.