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1.
J Oleo Sci ; 69(11): 1455-1465, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33055439

RESUMO

In this study, a new way to produce tofu with lactic acid bacteria (Lactobacillus casei, L. casei) and salt coagulant (magnesium sulfate) has been developed and optimized in order to improve the quality characteristics and the storage stability. Processing parameters (bean-water ratio, inoculation amount, magnesium sulfate concentration and pressing time) of tofu were studied. Yield, water holding capacity (WHC), texture and sensory were measured for evaluating quality characteristics of tofu. Based on the single factor and response surface methodology (RSM), the optimized conditions of tofu were determined as follows: bean-water ratio was 1:4 g/mL, fermentation time was 5 h at 37°C when the inoculation amount was 4.0%, magnesium sulfate concentration was 2.0 mol/L and pressing time was 1 h. Under the optimum conditions, the yield of the tofu was 140.45 g, the WHC was 87.25 %, the hardness was 420.36 g, and the tofu had better sensory characteristics, soft, uniform texture, as well as good flavor. The shelf life and stability of tofu during storage were also evaluated under the optimum conditions. The results showed that fermented tofu had a longer shelf life than unfermented tofu at room temperature. Compared with the "pasteurization + low temperature" group and "low temperature" group, the fermented tofu in the "microwave + low temperature" group had a longer shelf life and better-quality properties during storage. Tofu, prepared by the lactic acid bacteria fermentation and salt coagulant, would be accepted as a new type of tofu according to its quality characteristics and storage stability.


Assuntos
Manipulação de Alimentos/métodos , Conservação de Alimentos/métodos , Qualidade dos Alimentos , Armazenamento de Alimentos , Lactobacillus casei , Sulfato de Magnésio , Alimentos de Soja , Fermentação , Análise de Alimentos , Humanos , Concentração de Íons de Hidrogênio , Alimentos de Soja/análise , Alimentos de Soja/microbiologia , Paladar , Temperatura , Água/análise
2.
PLoS One ; 15(10): e0239971, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33048960

RESUMO

We determined bacterial migration into doenjang from its components, meju and solar salt using culture-based and 16S rRNA gene-based culture-independent techniques (pyrosequencing of total DNA). Pyrosequencing results suggested that the bacterial communities of meju, but not solar salt, significantly affected those of doenjang communities. Culture-based pyrosequencing analysis yielded similar results. These results indicate that most predominant bacterial species in doenjang migrated from meju, not solar salt. We therefore believe that the present study is one of the most comprehensive comparisons of bacterial communities of fermented soybeans using culture-dependent and -independent methods. Furthermore, pyrosequencing of the V3 and V4 regions of bacterial 16S rRNA did not distinguish among Bacillus amyloliquefaciens, B. siamensis, and B. velezensis as well as between Enterococcus faecium and E. hirae.


Assuntos
Bactérias/isolamento & purificação , Microbiologia de Alimentos , Alimentos de Soja/microbiologia , Bacillus/classificação , Bacillus/genética , Bacillus/isolamento & purificação , Bactérias/classificação , Bactérias/genética , Fermentação , Sequenciamento de Nucleotídeos em Larga Escala , Concentração de Íons de Hidrogênio , Microbiota , Filogenia , RNA Ribossômico 16S/química , RNA Ribossômico 16S/classificação , RNA Ribossômico 16S/metabolismo , Cloreto de Sódio/análise
3.
J Food Sci ; 85(10): 3113-3123, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32954501

RESUMO

White spots are commonly found in bean-based fermented food, which will significantly lower the product quality. This study aimed to analyze the composition of white spots and further reveal the source and influencing factors of white spots in bean-based fermented food using soybean paste as study model. The results showed that white spots were mainly composed of 40.96% free tyrosine and 37.94% tyrosine in combination form. During soybean paste fermentation, tyrosine was found to be produced by the actions of proteolytic enzymes secreted by Aspergillus oryzae 3.042 instead of the microbial metabolism and the excessive accumulation of tyrosine in soybean paste led to the formation of white spots. Among all influencing factors, high temperature treatment favored the formation of white spots. The existence of soy peptone and phenylalanine would postpone the precipitation of tyrosine while promoting the aggregation of the tyrosine precipitation. Field emission scanning electron microscope analysis showed that tyrosine would accumulate around the soybean protein particles and treatment at 120 °C would disrupt the structure of tyrosine-protein complex. Based on the above results, we proposed that treatment of soybean paste at temperature lower than 80 °C was the current practically applicable method to control the formation of white spots in soybean paste. PRACTICAL APPLICATION: This study developed a new idea to understand the composition and formation of white spots in soybean paste, which would provide guidance for prevention and control of white spots during the production of soybean paste for manufacturers and researchers.


Assuntos
Alimentos de Soja/análise , Soja/química , Aspergillus oryzae/metabolismo , Fermentação , Alimentos de Soja/microbiologia , Soja/microbiologia , Tirosina/análise , Tirosina/metabolismo
4.
Food Chem ; 329: 127118, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32512391

RESUMO

Sonication was applied to accelerate aroma formation and shorten fermentation time of soy sauce. Effects of sonication at 68 kHz on the aroma and aroma-producing Zygosaccharomyces rouxii and Tetragenococcus halophilus in moromis were investigated using sensory evaluation, SPME-GC-olfactometry/MS, viable cell counting and scanning electron microscopy. The sensory scores of caramel-like, fruity, alcoholic, floral, malty, smoky, sour and overall aroma in sonicated moromis were enhanced by 23.4%, 23.2%, 13.6%, 12.8%, 7.6%, 6.3%, 5.6% and 14.4%, respectively. Sensory scores of samples fermented for 90-180 days were higher than those of controls fermented for 180 days, suggesting that sonication could reduce fermentation time by 90 days. Thirty-four aroma-active compounds were detected from 85 volatile compounds in soy sauces. Sonication accelerated and elevated the formation of aroma compounds by chemical reactions. It also markedly increased the reproduction and cell permeability of both microorganisms in moromis, which favored the formation of aroma compounds by both strains.


Assuntos
Odorantes/análise , Alimentos de Soja/análise , Enterococcaceae , Fermentação , Cromatografia Gasosa-Espectrometria de Massas , Sonicação , Alimentos de Soja/microbiologia , Paladar , Zygosaccharomyces
5.
J Food Sci ; 85(6): 1642-1650, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32430953

RESUMO

The effects of different mucor strains (Mucor racemosus, Actinomucor, and Mucor wutungkiao) on aroma and taste profiles based on proteolysis, lipolysis, and their catabolism in oil furu were studied. Gas chromatography-mass spectrometry and relative odor activity were used to monitor the changes of key volatile compounds and the differences in the characteristic aroma contents of oil furu. Using principal component analysis, the different fermentation strains had an effect on aroma profiles. The volatile compounds from metabolism of protein and fatty acid contributed to the aroma of oil furu with different contribution from the different strains, presumably due to their different enzymes. The electronic tongue and free amino acid profiles also showed strain differences of taste. Based on these results, optimization of the amount of each of the different mucor strains during cofermentation might achieve better flavor.


Assuntos
Aromatizantes/química , Mucor/metabolismo , Odorantes/análise , Alimentos de Soja/microbiologia , Soja/química , Soja/microbiologia , Aminoácidos/química , Aminoácidos/metabolismo , Nariz Eletrônico , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Fermentação , Aromatizantes/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Mucorales/metabolismo , Alimentos de Soja/análise , Soja/metabolismo , Paladar , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/metabolismo
6.
Food Microbiol ; 90: 103408, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32336369

RESUMO

This study aimed to explore the core functional microbiotas related to flavor compounds involving in a naturally fermented soybean curd (plain sufu). Properties such as physicochemical parameters, flavor compounds (17 free amino acids, 21 fatty acids, and 14 aroma volatiles) and microbiota profiles were investigated, and their correlations were explored at 8 stages during production. Results from principal component analysis, multiple factor analysis, and partial least squares-discrimination analysis showed that these properties varied significantly in the eight stages. Furthermore, based on Pearson correlation coefficients and Variable importance for predictive components values between the microbiota profiles and flavor compounds, nine bacterial (Bacillus, Enterobacter, Lactobacillus, Sphingobacterium, Stenotrophomonas, Tetragenococcus, Trabulsiella, Unclassified, and Weissella) and six fungal (Alternaria, Sterigmatomyces, Actinomucor, Fusarium, Debaryomyces, Candida) genera were identified as core functional microbiotas significantly affecting the production of flavor compounds during the natural production. Overall, this study provided a comprehensive description of the dynamic changes of physicochemical parameters, flavor compounds, and microbiota profiles throughout the natural production of plain sufu. The similarities and variations among different stages, as well as correlation between flavor compounds and microbiotas would help to understand the mechanism of plain sufu production, and further to enhance the quality control of plain sufu.


Assuntos
Bactérias/metabolismo , Fermentação , Aromatizantes/análise , Fungos/metabolismo , Microbiota , Alimentos de Soja/microbiologia , Aminoácidos/análise , Bactérias/classificação , Bactérias/isolamento & purificação , Fenômenos Fisiológicos Bacterianos , China , Ácidos Graxos/análise , Alimentos e Bebidas Fermentados/microbiologia , Fungos/classificação , Fungos/isolamento & purificação , Odorantes/análise , Compostos Orgânicos Voláteis/análise
7.
PLoS One ; 15(3): e0230916, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32214369

RESUMO

Ecology studies showed that esophageal and gastric cancers are directly correlated with the consumption of processed foods. The carcinogenicity of traditional Chinese fermented foods such as douchi (fermented black beans or fermented black soybeans) is due to the presence of carcinogenic N-nitroso compounds, which are derived from biogenic amines. Among the various biogenic amines that can act as precursors of N-nitroso compounds, histamine and tyramine are considered to be the most toxic and are of public health concern when present in food. We have examined some douchi products on the market, and significant amounts of histamine and tyramine were found. The use of fermentation starters generated by subculturing fermented products with unknown microbiota would induce the risk of biogenic amines. As the microbiota used in fermentation is a crucial factor in determining the biogenic amines of fermented food, it is hypothesized that the possible harmful effects of douchi can be minimized through the use of fermentation starters composed of probiotic bacteria. This is the first study to investigate the potential of using probiotic bacteria in manufacturing douchi. Lactobacillus rhamnosus GG (LGG), Lactobacillus casei Shirota (LcS) and Escherichia coli Nissle 1917 (EcN) were used to ferment black beans in this study, and no tyramine was detected in black bean samples incubated with these three strains anaerobically at 37°C or 20°C. The starter culture strains, temperature and presence of oxygen during the incubation period were found to be critical to the generation of biogenic amines. The findings of this study can provide evidence-based insights and warrant further investigations on the potential of reducing the harmful compounds in food fermented with probiotic bacteria as well as the sensory evaluation of douchi fermented with probiotic bacteria.


Assuntos
Bactérias/metabolismo , Aminas Biogênicas/análise , Fermentação , Probióticos/metabolismo , Alimentos de Soja/análise , Alimentos de Soja/microbiologia
8.
J Agric Food Chem ; 68(9): 2757-2764, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32026695

RESUMO

Aspergillus oryzae 3.042 was mutagenized using atmospheric and room-temperature plasma (ARTP) technology to enhance its salt-tolerant proteases activity. Compared to the starting strain, mutant H8 subjected to 180 s of ARTP treatment exhibited excellent genetic stability (15 generations), growth rate, and significantly increased activities of neutral proteases, alkaline proteases, and aspartyl aminopeptidase during fermentation. Mutant H8 significantly enhanced the contents of 1-5 kDa peptides, aspartic acid, serine, threonine, and cysteine in soy sauce by 16.61, 7.69, 17.30, 8.61, and 45.00%, respectively, but it had no effects on the contents of the other 14 free amino acids (FAAs) due to its slightly enhanced acidic proteases activity. Analyses of transcriptional expressions of salt-tolerant alkaline protease gene (AP, gi: 217809) and aspartyl aminopeptidase gene (AAP, gi: 6165646) indicated that their expression levels were increased by approximately 30 and 27%, respectively. But no mutation was found in the sequences of AP and AAP expression cassettes, suggesting that the increased activities of proteases in mutant H8 should be partially attributed to the increased expression of proteases. ARTP technology showed great potential in enhancing the activities of salt-tolerant proteases from A. oryzae.


Assuntos
Aspergillus oryzae/enzimologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Cloreto de Sódio/metabolismo , Aspergillus oryzae/química , Aspergillus oryzae/genética , Aspergillus oryzae/metabolismo , Estabilidade Enzimática , Fermentação , Proteínas Fúngicas/química , Mutagênese , Peptídeo Hidrolases/química , Alimentos de Soja/análise , Alimentos de Soja/microbiologia
9.
Sci Rep ; 10(1): 1081, 2020 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-31974506

RESUMO

We aimed to develop a consortium of starter culture of effective microorganisms to prepare doenjang, a traditional Korean fermented food. Different ratios of Bacillus subtilis TKSP 24 (B), Aspergillus oryzae complex (A), Rhizopus nigricans (also named as Rhizopus stolonifera) (R), and Mucor racemosus 15 (M15) were selected as meju starter cultures to produce doenjang with improved quality. Microbial strain combinations (B: A: R and B: M15: R) were mixed separately at three different ratios [1:1:1 (w/w), 1:0.5:1.5 (w/w), and 1:1.5:0.5 (w/w)] to prepare BAR-1, BAR-2, BAR-3, BM15R-1, BM15R-2, and BM15R-3 doenjang samples. Quantitative analyses included free amino acids, free sugar, volatile and non-volatile organic acids, cellular antioxidant activity along with the presence of biogenic amines and aflatoxins, and microbial counts. Total free amino acids responsible for the sweet taste of doenjang were highest in BAR-2 (322.50 mg/100 g) and BM15R-3 (320.07 mg/100 g). Total volatile organic acid was highest in BAR-1 compared to other preparations. All doenjang samples had biogenic amines, especially histamine, below the toxicity level (500 mg/kg). Also, the aflatoxin and hazardous microbial count in the tested doenjang samples were below the level of toxicity. The findings suggest that use of multiple microbial strains in combination with R. nigricans as a starter culture could be a novel and effective approach to improve the nutrition and safety of fermented soybean food products of doenjang.


Assuntos
Rhizopus/metabolismo , Alimentos de Soja/microbiologia , Soja/microbiologia , Aflatoxinas/análise , Aflatoxinas/metabolismo , Aminoácidos/análise , Aminoácidos/metabolismo , Aminas Biogênicas/análise , Aminas Biogênicas/metabolismo , Fermentação , Microbiologia de Alimentos , Inocuidade dos Alimentos , Controle de Qualidade , República da Coreia , Alimentos de Soja/análise , Soja/química
10.
J Food Sci ; 85(1): 165-172, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31898817

RESUMO

Sufu is a form of food derived from traditional Chinese fermented soybean. It has a unique flavor and contains abundant nutrients. With demands for healthy food on the rise, a higher level of sufu functionality is required. In fermentation of soybean-derived products, lactic acid bacteria (LAB) are widely used as an adjunct culture, which provides health benefits and enhances flavor of food. Among LAB, Lactobacillus brevis has the potential to generate γ-aminobutyric acid (GABA), which is well-known for its physiological functions. In this study, L. brevis was added to bacteria-fermented sufu to evaluate its impacts on sufu quality. Sufu was produced via co-inoculation with Bacillus subtilis and L. brevis (group A sufu) or a single inoculation with B. subtilis (group B sufu). Metabolite changes in the two groups during fermentation were investigated and physicochemical changes were observed. The results indicated that the addition of L. brevis increased the concentration of GABA and decreased the concentrations of histamine and serotonin. The concentrations of volatile compounds, such as esters and acids, especially 2-methyl-butanoic acid ethyl ester, as well as the concentrations of phenylethyl alcohol and 3-methyl-butanol were significantly higher in group A. Inoculation of L. brevis changed the metabolite profile of sufu and improved its functionality and safety of edibility. The current study explored the potential of applying L. brevis to the manufacture of bacteria-fermented sufu.


Assuntos
Bacillus subtilis/metabolismo , Aromatizantes/análise , Lactobacillus brevis/metabolismo , Alimentos de Soja/microbiologia , Ésteres/metabolismo , Fermentação , Aromatizantes/metabolismo , Alimentos de Soja/análise , Soja/química , Soja/metabolismo , Soja/microbiologia , Ácido gama-Aminobutírico/análise , Ácido gama-Aminobutírico/metabolismo
11.
Food Funct ; 11(1): 640-648, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31895399

RESUMO

Aspergillus oryzae is a common starter in the soy sauce industry and struggles to grow under complex fermentation conditions. However, little is known about the flavor formation mechanism under osmotic conditions (low-temperature and high-salt) in A. oryzae. This work investigated the flavors and the relative protein expression patterns by gas chromatography-mass spectrometry (GC-MS) and proteomic analysis. Low-temperature and a high-salt content are unfavorable to the secretion of hydrolases and the formation of fragrant aldehydes. The aldehyde contents under osmotic conditions were reduced to 1.4-3.7 times lower than that of the control. Besides, copper amine oxidases which decreased under low-temperature stress and salt stress were shown to be important in catalyzing the oxidative deamination of several amine substrates to fragrant aldehydes. Furthermore, alcohol dehydrogenase and polyketide synthase are beneficial to the formation of alcohols and aromatic flavors under low-temperature stress and salt stress. Particularly, the ethanol content under 16 °C stress was 3.5 times higher than that under 28 °C.


Assuntos
Aspergillus oryzae/metabolismo , Aromatizantes/química , Alimentos de Soja/microbiologia , Soja/microbiologia , Aromatizantes/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Osmose , Proteômica , Alimentos de Soja/análise , Soja/química , Soja/metabolismo
12.
Food Microbiol ; 86: 103340, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703864

RESUMO

Red sufu is a traditional food produced by the fermentation of soybean. In this study, sufu samples were periodically collected during the whole fermentation to investigate the dynamic changes of fungal and bacterial communities using high-throughput sequencing technology. The overall process can be divided into pre- and post-fermentation. During post-fermentation, the pH value showed a gradual decrease over time while the amino nitrogen content increased. Trichosporon, Actinomucor and Cryptococcus were the main genera in pre-fermentation while Monascus and Aspergillus were dominant in post-fermentation. This huge shift in fungal composition was caused by process procedure of pouring dressing mixture. However, the bacterial composition was not greatly changed after pouring dressing mixture, the Acinetobacter and Enterobacter were the predominant genera throughout the whole process. Furthermore, Bacillus species were first detected after adding dressing mixture, but declined abruptly to a very low level (0.07%) by the end of the fermentation. Our work demonstrates the dynamic changes of physicochemical properties and microbial composition in every fermentation stage, the knowledge of which could potentially serve as a foundation for improving the safety and quality of sufu in the future.


Assuntos
Bactérias/isolamento & purificação , Fungos/isolamento & purificação , Microbiota , Alimentos de Soja/microbiologia , Soja/microbiologia , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Fermentação , Fungos/classificação , Fungos/genética , Fungos/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Alimentos de Soja/análise , Soja/metabolismo
13.
Food Microbiol ; 86: 103329, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703874

RESUMO

Four sets of doenjang (traditional Korean fermented soybean paste) with 9%, 12%, 15%, and 18% solar salt concentrations were prepared and their pH, microbial abundances and communities, metabolites, and volatile compounds were analyzed periodically during the entire fermentation. The speeds of decrease in pH and increase in microbial abundances, representing microbial activity, were higher during early fermentation in lower (9% and 12%) salt doenjang. Microbial abundances in 15% and 18% salt doenjang were significantly lower than in the 9% and 12% salt doenjang, indicating low microbial activity. Community analysis revealed that Bacillus, Staphylococcus, and Clostridium and Aspergillus, Scopulariopsis, Fusarium, Mucor, and Penicillium, which might be derived from doenjang-meju used for preparing doenjang, were identified as major bacterial and fungal genera, respectively, in all doenjang samples. Weissella, Tetragenococcus, Oceanobacillus, and Debaryomyces, not dominant in doenjang-meju, were also identified as major groups in low salt doenjang. Metabolite analysis showed that amino acid profiles were relatively similar independent of salt concentrations and microbial growth, indicating important roles of indigenous proteases present in doenjang-meju, not microbial activity during doenjang fermentation, in amino acid production. The metabolism of free sugars to organic acids and biogenic amine production were greater in lower salt doenjang, which might be associated with the growth of microbes, particularly lactic acid bacteria. A higher level of and more diverse volatile compounds were identified in lower salt doenjang, indicating close association with microbial growth. This study provides a deeper understanding of doenjang fermentation and insight into the development of low salt doenjang.


Assuntos
Alimentos e Bebidas Fermentados/microbiologia , Cloreto de Sódio/análise , Soja/microbiologia , Ácidos/análise , Ácidos/metabolismo , Aminoácidos/análise , Aminoácidos/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Aminas Biogênicas/análise , Aminas Biogênicas/metabolismo , Fermentação , Alimentos e Bebidas Fermentados/análise , Fungos/classificação , Fungos/genética , Fungos/isolamento & purificação , Fungos/metabolismo , Cloreto de Sódio/metabolismo , Alimentos de Soja/análise , Alimentos de Soja/microbiologia
14.
J Food Sci ; 84(12): 3726-3734, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31834968

RESUMO

Ten probiotic cultures were screened for the ability to hydrolyze soy proteins and bile salt deconjugation (BSD) to select one lactobacilli and one bifidobacteria strain to produce fermented soy beverages (FSBs) containing acerola byproduct (ABP). Next, the effect of the strains and the ABP on the technological and sensory characteristics of these beverages was evaluated during refrigerated storage for up to 28 days. None of the tested strains presented any proteolytic activity against soy proteins. Among the probiotic strains, the best BSD activities were observed for Lactobacillus acidophilus LA-5 and Bifidobacterium longum BB-46, which were further employed, individually or combined, to produce FSB supplemented or not with ABP, using Streptococcus thermophilus TH-4 as a starter, and the effect of these strains and ABP on the technological and sensory acceptability of FSB was evaluated. The probiotic strains did not influence FBS texture parameters, but ABP increased firmness in the ready product. BB-46 increased acidity, therefore decreasing acceptance, whereas the presence of LA-5 and/or ABP increased acceptance, even though the appearance was negatively affected by ABP after 21 days of storage. Thus, the presence of LA-5 and ABP contributed for the sensory acceptance of the FSBs without affecting their technological features. PRACTICAL APPLICATION: Lactobacillus acidophilus LA-5, Bifidobacterium longum BB-46, and/or acerola byproduct (ABP) were applied in the production of fermented soy beverages (FSBs). Principal components analysis was used to evaluate the formulations of the 23 factorial design and the sensory attributes and the effect of storage independently and covariance was the matrix type used for mapping purposes. LA-5 and ABP contributed for the sensory acceptance of FSB, without affecting their technological features, and could be used by food processing companies after scaling up, also reducing the environmental impact by decreasing discarding byproducts, which are sources of bioactive compounds.


Assuntos
Alimentos e Bebidas Fermentados , Lactobacillus/metabolismo , Malpighiaceae/química , Probióticos/metabolismo , Alimentos de Soja , Fermentação/fisiologia , Alimentos e Bebidas Fermentados/análise , Alimentos e Bebidas Fermentados/microbiologia , Manipulação de Alimentos , Alimentos de Soja/análise , Alimentos de Soja/microbiologia
15.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 50(5): 714-719, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31762243

RESUMO

OBJECTIVE: To select and identify the bacterium which highly produces protease and ß-D-glucosidase from 72 strains of Shuidouchi from Sichuan, and to provide evidence for further research on its nutritional value and fermentation strain exploiting. METHODS: Casein degradation test and pNPG chemical test were applied respectively to detect the capacity to produce protease and ß-D-glucosidase of each strain. Characteristics of morphology, biochemistry, 16S rRNA and MALDI-TOF-MS were used to identify the fermentation strain, which genetic stability, curves of growth and enzyme producing were also obtained. RESULTS: The strain with the highest enzyme activity of ß-D-glucosidase (0.084 U/L) among the top 10 strains for producing protease was selected as the fermentation strain and was identified as Bacillus subtilis, which curves of growth and enzyme producing conformed as well. The result of genetic stability showed that capacity of enzyme producing was stable until the 10th generation. CONCLUSIONS: The fermentation strain which highly produced protease and ß-D-glucosidase was selected from 72 strains of shuidouchi from Sichuan and was identified as Bacillus subtilis.


Assuntos
Bacillus subtilis/enzimologia , Alimentos e Bebidas Fermentados/microbiologia , Glucosidases/biossíntese , Peptídeo Hidrolases/biossíntese , Alimentos de Soja/microbiologia , China , Fermentação , RNA Ribossômico 16S
16.
Nutrients ; 11(11)2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31726743

RESUMO

Fermented foods in Korea contain a lot of salt. Although salt is reported to exacerbate health trouble, fermented foods have beneficial effects. We hypothesized that doenjang could reduce blood pressure in Sprague-Dawley (SD) rats fed a high-salt diet. Eighteen SD rats were divided into three groups: normal-salt (NS) group, high-salt (HS) group, and high-salt with doenjang (HSD) group. The salinity of doenjang and saltwater was adjusted to 8% using Mohr's method. Blood pressure was significantly reduced in the HSD group compared with the HS group. Water intake and urine excretion volume has significantly increased in the HS group compared with the HSD group. The excreted concentrations of urine sodium, urine potassium, and feces potassium significantly increased in the HSD group compared with the HS and NS groups. Renin level was significantly decreased in the HSD group compared to the other groups. These results indicate that eating traditional salty fermented food is not a direct cause of hypertension, and the intake of doenjang in normal healthy animals improved blood pressure.


Assuntos
Pressão Sanguínea , Hipertensão/dietoterapia , Cloreto de Sódio na Dieta , Alimentos de Soja , Ração Animal , Fenômenos Fisiológicos da Nutrição Animal , Animais , Modelos Animais de Doenças , Ingestão de Líquidos , Hipertensão/etiologia , Hipertensão/fisiopatologia , Rim/fisiopatologia , Masculino , Estado Nutricional , Valor Nutritivo , Ratos Sprague-Dawley , Medição de Risco , Alimentos de Soja/microbiologia , Alimentos de Soja/toxicidade , Micção
17.
ACS Appl Mater Interfaces ; 11(47): 43949-43963, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31684721

RESUMO

A graphene aerogel (GA) with a three-dimensional (3D) structure, ultra-lightweight nature, and high hydrophobicity was simply fabricated by the one-step pyrolysis of glucose and ammonium chloride. The as-synthesized GA exhibited a 3D interconnected microporous architecture with a high surface area of ∼2860 m2 g-1 and pore volume of 2.24 cm3 g-1. The hydrophobic GA (10 mg 100 mL-1) demonstrated rapid and excellent adsorption performance for the removal of food toxins such as various biogenic amines (histamine, cadaverine, and spermine) and the hazardous bacterium Staphylococcus aureus (a food contaminant and a cause of poor wound healing) from a liquid matrix with a maximum simultaneous adsorption capacity for multiple biogenic amines of >85.19% (histamine), 74.1% (cadaverine), and 70.11% (spermidine) and a 100% reduction in the viable cell count of S. aureus within 80 min of interaction. The outstanding adsorption capacity can be attributed to a highly interconnected porous network in the 3D architecture and a high surface-to-volume ratio. A case study using soy sauce spiked with multiple biogenic amines showed successful removal of toxins with excellent recyclability without any loss in absorption performance. Biocompatibility of the GA in terms of cell viability was observed even at high concentrations (83.46% and 75.28% at 25 and 50 mg mL-1, respectively). Confirmatory biocompatibility testing was conducted via live/dead cell evaluation, and the morphology of normal lung epithelial cells was examined via scanning electron microscopy showed no cellular shrinkage. Moreover, GA showed excellent removal of live colonies of S. aureus from the food matrix and immunoblotting analysis showed elevated protein expression levels of ß-catenin and α-SMA (α-smooth muscle actin). The biocompatible sugar-based GA could simultaneously adsorb multiple biogenic amines and live bacteria and was easy to regenerate via simple separation due to its high floatability, hydrophobicity, surface area, and porosity without any structural and functional loss, making it especially relevant for food safety and biomedical applications.


Assuntos
Aminas Biogênicas/química , Grafite/química , Alimentos de Soja/microbiologia , Staphylococcus aureus/química , Actinas/genética , Actinas/metabolismo , Adsorção , Proliferação de Células , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Contaminação de Alimentos/análise , Géis/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/isolamento & purificação , beta Catenina/genética , beta Catenina/metabolismo
18.
Pediatrics ; 144(4)2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31519792

RESUMO

BACKGROUND: In 2017, we conducted a multistate investigation to determine the source of an outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 infections, which occurred primarily in children. METHODS: We defined a case as infection with an outbreak strain of STEC O157:H7 with illness onset between January 1, 2017, and April 30, 2017. Case patients were interviewed to identify common exposures. Traceback and facility investigations were conducted; food samples were tested for STEC. RESULTS: We identified 32 cases from 12 states. Twenty-six (81%) cases occurred in children <18 years old; 8 children developed hemolytic uremic syndrome. Twenty-five (78%) case patients ate the same brand of soy nut butter or attended facilities that served it. We identified 3 illness subclusters, including a child care center where person-to-person transmission may have occurred. Testing isolated an outbreak strain from 11 soy nut butter samples. Investigations identified violations of good manufacturing practices at the soy nut butter manufacturing facility with opportunities for product contamination, although the specific route of contamination was undetermined. CONCLUSIONS: This investigation identified soy nut butter as the source of a multistate outbreak of STEC infections affecting mainly children. The ensuing recall of all soy nut butter products the facility manufactured, totaling >1.2 million lb, likely prevented additional illnesses. Prompt diagnosis of STEC infections and appropriate specimen collection aids in outbreak detection. Child care providers should follow appropriate hygiene practices to prevent secondary spread of enteric illness in child care settings. Firms should manufacture ready-to-eat foods in a manner that minimizes the risk of contamination.


Assuntos
Surtos de Doenças/estatística & dados numéricos , Infecções por Escherichia coli/epidemiologia , Escherichia coli O157 , Doenças Transmitidas por Alimentos/epidemiologia , Escherichia coli Shiga Toxigênica , Alimentos de Soja/microbiologia , Adolescente , Idoso , Criança , Creches/estatística & dados numéricos , Pré-Escolar , Infecções por Escherichia coli/microbiologia , Fast Foods/efeitos adversos , Fast Foods/microbiologia , Feminino , Manipulação de Alimentos , Doenças Transmitidas por Alimentos/microbiologia , Síndrome Hemolítico-Urêmica/epidemiologia , Síndrome Hemolítico-Urêmica/microbiologia , Humanos , Lactente , Masculino , Recall e Retirada de Produto , Alimentos de Soja/efeitos adversos , Estados Unidos/epidemiologia
19.
J Food Sci ; 84(9): 2441-2448, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31429494

RESUMO

The purpose of the present study was to evaluate the volatile profile of Kedong sufu, which is a typical bacteria-fermented soybean product in China, using solid phase microextraction coupled to gas chromatography and mass spectrometry and to reveal the evolution and diversity of flavor substances for this specialty. A total of 75 compounds were identified, including 35 esters, 4 alcohols, 4 phenols, 4 aldehydes, 7 acids, 10 ketones, and 11 other compounds from sufu samples during ripening. Some volatile compounds increased with ripening time, especially hexadecenoic acid ethyl ester, methoxy acetic acid pentyl ester, benzene propanoic acid ethyl ester, ethyl 9-hexadecenoate, ethyl oleate, ethanol, 3-methyl-1-butanol, 5-methoxy-1-pentanol, and eugenol; these compounds enriched the flavors and provided the typical savory taste of Kedong sufu. PRACTICAL APPLICATION: This research elucidated the formation of flavor substances in sufu. For traditional fermented foods, this study provides a scientific basis for promoting the generation of typical flavor substances and for the precise determination of maturity time.


Assuntos
Aromatizantes/química , Alimentos de Soja/análise , Soja/química , Compostos Orgânicos Voláteis/química , Bactérias/metabolismo , China , Fermentação , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos , Microextração em Fase Sólida/métodos , Alimentos de Soja/microbiologia , Soja/metabolismo , Soja/microbiologia , Paladar
20.
Food Funct ; 10(9): 5282-5289, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31465046

RESUMO

Lactobacillus (Lb.) plantarum is typically used as a starter culture in salt-fermented foods. Here we report 3-4% NaCl reducing the antimicrobial activity of Lb. plantarum strain YM-4-3, owing to the decrease of bacterial growth, plantaricin activity and expression levels of plantaricin biosynthesis-related genes (PBGs). Meanwhile, 1% NaCl promoted slightly the growth of YM-4-3 and up-regulated the expression of PBGs to the greatest level. The results from a spoilage experiment of fermented soybean products revealed that the 1% NaCl and YM-4-3 treatment group had the longest shelf life representing the minimum number of pathogenic bacteria and the lowest degree of mildew. Therefore, a combination of Lb. plantarum with a low concentration of salt, such as 1% NaCl, is a recommended condition for preparing fermented foods.


Assuntos
Lactobacillus plantarum/metabolismo , Soja/microbiologia , Bactérias/crescimento & desenvolvimento , Armazenamento de Alimentos , Concentração de Íons de Hidrogênio , Lactobacillus plantarum/genética , Lactobacillus plantarum/crescimento & desenvolvimento , Cloreto de Sódio , Alimentos de Soja/análise , Alimentos de Soja/microbiologia , Soja/química
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