Degree Of Fermentation Research Articles

Stainless steel wool as novel bioanode for microbial electrolysis cells: A systematic study of materials

In the last years, microbial electrochemical technologies have received increasing attention due to their promising environmental potential. However, the identification of the most suitable materials for further development of these technologies tends to be challenging, especially for operation under realistic wastewater conditions. The objective of the present work is to carry out a systematic comparison of six anode materials (stainless-steel wool, carbon paper, graphite felt, graphite plate, graphite foil, and stainless-steel mesh) for microbial electrolysis cells operated for the treatment of brewery wastewater and determine the best material of these in sight of its electrochemical performance. For this purpose, the medium was semisynthetic brewery wastewater of low buffer capacity and low conductivity. The results suggest, that the degree of fermentation and characteristics of the studied media have only a minor impact on the limiting current density of the bioanodes. Here, the limiting current density of microbial anodes with stainless-steel wool (0.45 ± 0.07 mA·cm−2), a not so extensively studied promising material, outperformed commonly used materials such as graphite felt, without evidence of corrosion.

Study on the Technology of Low Alcohol Hawthorn Flavor Beer

Hawthorn fruit is bright red in color, contains a variety of nutrients, and has many health effects. In this paper, through the study of yeast, fermentation temperature, acid reduction, high residual sugar and other factors, we finally selected NO303 Aerospace yeast with rich ester aroma and low fermentation degree reserved in the yeast bank of Qilu University of technology for fermentation. Fermentation temperature is 19.0℃, the main fermentation duration is:1-2days, total fermentation time is about 10 days. The physical and chemical indexes of low alcohol hawthorn beer are as follows: Original wort concentration is 11°P, residual sugar is 9.8°P, alcohol level is 0.45 %vol, total acid is 2.55mL/100mL, pH3.87, chroma is 13.5EBC. Finally, low alcohol hawthorn beer with light red color, hawthorn aroma and strong ester aroma was obtained. The beer has low acidity, balanced between acidity and sweetness, unique taste and low alcohol content. It is more like a carbonated beverage with strong killing taste and is suitable for the general public, especially young female consumers.

Rapid Quantitative Analysis of Metabolites in Kimchi Using LC-Q-Orbitrap MS.

Kimchi is a traditional Korean salted spontaneous lactic acid bacteria (LAB)-fermented food made using various vegetables. Organic acids, free sugars, and amino acids are key metabolites produced during LAB fermentation that determine the taste and quality of kimchi. However, each metabolite is typically analyzed using an independent analytical method, which is time-consuming and expensive. Therefore, in this study, we developed a method based on LC-Q-Orbitrap MS using which 20 types of representative fermented kimchi metabolites were selected and simultaneously analyzed within 10 min. The established method was validated, and its detection and quantification limits, linearity, precision, and accuracy were found to satisfy the Association of Official Agricultural Chemists (AOAC) validation guidelines. The 20 metabolites were simultaneously extracted from kimchi with different degrees of fermentation and quantitatively analyzed using LC-Q-Orbitrap MS. These results were analyzed using linear discriminant analysis and heat mapping, and the metabolites were grouped into early, middle, and late stages of fermentation. Malic acid (6.518-7.701 mMol) was only present in the initial stage of fermentation, and l-phenylalanine rapidly increased from the middle stage (2.180 mMol) to late stage (4.770 mMol). Lactic acid, which is representative of the sour taste of kimchi, was detected in the middle stage and increased rapidly up to 74.452 mMol in the late stage. In summary, in this study, 20 major kimchi metabolites were accurately analyzed within 10 min and grouped based on the degree of fermentation. Therefore, the method established in this study accurately and rapidly provides information on kimchi consumption and fermentation that could be highly valuable to the kimchi industry and kimchi consumers.

Effect of grape seed proanthocyanidin on the structural and physicochemical properties of bread during bread fermentation stage

Bread was prepared using wheat flour with grape seed proanthocyanidin (GSP) (0.4%). GSP improved the textural properties of bread including hardness, cohesiviness, gumminess and chewiness. At the last stage of fermentation, GSP reinforced the gluten microstructure with increased the disulfide bonds and hydrophobic interaction and α-helix in the secondary structures. Moreover, GSP addition could increase the total phenolics and antioxidative acitivity of the bread significantly. In addition, the degree of fermentation had a strong influence on the dough forces, and the reasonable control of bread fermentation time was beneficial to improve the bread quality, which provided a reference for the bread processing industry.

Bread Fermentation Degree Classification by Image Texture Analysis

Bread Fermentation Degree Classification by Image Texture Analysis

Qualitative and quantitative analysis of the pile fermentation degree of Pu-erh tea

During the pile fermentation (PF) process, changes to the polyphenol composition directly affect the quality of Pu-erh tea. In this study, we have applied laboratory-made computer vision system (CVS) and miniature near-infrared spectroscopy (NIRS) to the at-line rapid detection of the PF degree of Pu-erh tea at an industrial scale. High-performance liquid chromatography was used for determining the content of catechins (EGCG, EGC …) and gallic acid (GA). Based on the least-square support vector machine (LSSVM) qualitative model analysis, the texture features and color information extracted by CVS better predicted the degree of PF with a prediction set of 99.30% and calibration set of 100.00% compared to the spectral information extracted by NIRS. The best quantitative models for total catechins (TC), GA/TC, and red and green values of the tea infusion (R-TI, G-TI) were obtained with residual prediction deviations (RPD) of 4.76, 2.36, 5.18, and 4.71, respectively, based on CVS fusion data. And the optimal PF degree of Pu-erh tea was defined when the predicted values of TC, GA/TC, R-TI, and G-TI were in the ranges of 0.46 ± 0.08 mg/g, 19.04 ± 6.67, 74.81 ± 6.37, and 29.81 ± 2.46, respectively. In-situ quality monitoring of Pu-erh tea PF was realized.

Tea (Camellia sinensis) ameliorates DSS-induced colitis and liver injury by inhibiting TLR4/NF-κB/NLRP3 inflammasome in mice

The gut-liver axis is a bidirectional relationship between the gut with its microbiota and the hepatic. Ulcerative colitis (UC) disrupts the intestinal barrier and influx of intestinal microorganisms and their products into the liver, which trigger liver injury. Tea consumption is associated with a low incidence of UC in Asian countries. In this study, we revealed the mechanisms of six types of tea water extracts (TWEs) obtained from the leaves of Camellia sinensis on the dextran sodium sulfate (DSS)-induced colitis and liver injury in mice. The TWEs significantly restored mucin production and increased the expression levels of tight junction (TJ) proteins such as zonula occludens-1 (ZO-1), occluding, and claudin-1. In addition, TWEs also reduced the levels of pro-inflammatory cytokines in the colon and liver tissue by inactivating the NF-κB/NLRP3. Moreover, TEWs treatment promoted the integrity of the intestinal barrier to reduce serum lipopolysaccharide (LPS) levels, thereby reducing liver injury caused by intestinal microbial translocation and LPS induction. Analysis of 16 S rRNA microbial sequencing revealed that tea water extracts (TWEs) restored the DSS-induced gut dysbiosis. Interestingly, our results showed that the degree of fermentation of tea leaves was negatively associated with the alleviation of DSS-induced colitis effects, and there was also an overall negative trend with colitis-induced liver injury, except for black tea. Taken together, tea consumption mitigated DSS-induced colitis and liver injury in mice via inhibiting the TLR4/NF-κB/NLRP3 inflammasome pathway.

Antioxidant and hypoglycemic activity of tea polysaccharides with different degrees of fermentation

Four polysaccharides (GTPS, OTPS, BTPS and DTPS) were extracted from green tea, oolong tea, black tea and dark tea respectively. The physical and chemical properties, antioxidant and hypoglycemic activities were studied. Structural analysis showed that these tea polysaccharides were glycoprotein complexes, and there were significant differences in microstructure, protein, total sugar and uronic acid content. They were all composed of multiple monosaccharides and different molar ratios. In terms of antioxidant activity, completely fermented BTPS and DTPS had higher activity. Regarding to hypoglycemic effects, BTPS showed higher α-glucosidase inhibitory activity in vitro. And in the treatment of type 2 diabetes mice, Oral BTPS significantly controlled the levels of blood glucose, TG, TC, LDL-C, Cr, UREA, ALT and AST in diabetic mice, and improved insulin resistance. Histopathological observation further confirmed that BTPS can alleviate liver injury caused by hyperglycemia and hyperlipidemia. Data showed that BTPS significantly improved hyperglycemia and liver function in diabetic mice.

Modification of sago flour by fermentation of Lactic Acid Bacteria

Indonesia is one of the countries with a high level of wheat consumption, where wheat flour is still imported. Therefore, food diversification need to be carried out and developed by utilizing local raw materials, such as sago. This study aims to determine the effect of fermentation time (0 hours, 24 hours, 48 hours, 72 hours, 96 hours, 120 hours) and the type of fermentation (Spontaneous Fermentation and Lactobacillus plantarum Fermentation) on several physicochemical properties of sago flour. This research was arranged in a completely randomized design (CRD) with factorial pattern, which consisted of factor A (type of fermentation) and factor B (length of fermentation). The treatments were analyzed using analysis of variance. When If the treatment was significantly different, it was continued with Duncan’s Test. The parameters observed were Total LAB, starch content, amylose content, and whiteness degree. The results showed that the type of fermentation Lactobacillus plantarum had a higher total bacterium (6.5474 Log CFU/ml) compared to total bacteria in spontaneous fermentation (5.2090 Log CFU/ml), the starch content in the fermentation of Lactobacillus plantarum (39.43%) was optimum at 48 hours. while spontaneous fermentation was at 96 hours (38.19%), the optimum amylose in Lactobacillus plantarum fermentation was at 24 hours (4.00%) while spontaneous fermentation was at 120 hours (4.15%), The white degree of fermentation of Lactobacillus plantarum was optimum at 72 hours (90.49) spontaneous fermentation at 48 hours (87.20).

Neuroprotective effects of fermented tea in MPTP-induced Parkinson's disease mouse model via MAPK signaling-mediated regulation of inflammation and antioxidant activity

Parkinson’s disease (PD) is a neurodegenerative disorder that is characterized by dopaminergic neuronal damage. In this study, three tea extracts from Hadong, Korea, were evaluated in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity damage model (C57BL/6 mice) for their therapeutic effects against PD: green tea (GT), semi-fermented tea (SFT), and fermented tea (FT). Theaflavin content in the teas increased but catechin content decreased with the degree of fermentation. In addition, SFT showed the highest theanine and γ-aminobutyric acid contents. SFT at a concentration of 25 μg/mL showed the highest activity in the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay among all samples. Furthermore, the 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activity of 25 μg/mL SFT was higher than that of l-ascorbic acid. Fermented tea suppressed the expression of inflammatory cytokines, such as interleukin-6, tumor necrosis factor-alpha, inducible nitric oxide synthase, cyclooxygenase-2, and macrophage-1, as well as inhibited overexpression of apoptotic signals, including p-53, cleaved caspase-3, and poly (ADP-ribose) polymerase-1. Moreover, GT, SFT, and FT regulated the MPTP-induced oxidative stress-related factors, including superoxide dismutase, glutathione-S-transferase, and nicotinamide adenine dinucleotide phosphate oxidase 4. Fermented tea also alleviated MPTP-induced behavioral impairment and dopaminergic neuronal damage and reduced α-synuclein levels. These results indicate that fermented tea is effective for the treatment of neuro-inflammatory, neuro-apoptotic, and neuro-oxidative disorders.

Detection of the Inoculated Fermentation Process of Apo Pickle Based on a Colorimetric Sensor Array Method.

Apo pickle is a traditional Chinese fermented vegetable. However, the traditional fermentation process of Apo pickle is slow, easy to ruin, and cannot be judged with regard to time. To improve fermentation, LP-165 (L. Plantarum), which has a high salt tolerance, acidification, and growth capacity, was chosen as the starter culture. Meanwhile, a colorimetric sensor array (CSA) sensitive to pickle volatile compounds was developed to differentiate Apo pickles at varying degrees of fermentation. The color components were extracted from each dye in the color change profiles and were analyzed using principal component analysis (PCA) and linear discriminant analysis (LDA). The fermentation process of the Apo pickle was classified into four phases by LDA. The accuracy of backward substitution verification was 99% and the accuracy of cross validation was 92.7%. Furthermore, the partial least squares regression (PLSR) showed that data from the CSA were correlated with pH total acid, lactic acid, and volatile acids of the Apo pickle. These results illustrate that the CSA reacts quickly to inoculated Apo pickle and could be used to detect fermentation.

Dynamic change of oligopeptides and free amino acids composition in five types of tea with different fermentation degree processed from the same batch of fresh tea (Camelilia Sinensis. L.) leaves

Our previous studies have confirmed oligopeptides could be meaningful to tea taste and biofunction. As the total content of oligopeptide among different tea types were varied. It is a natural speculation that certain tea processing step could be vital for oligopeptides enrichment. In current study, five types of traditional Chinese tea were produced from the same batch of fresh leaves. Step processing samples were acquired through which to profile the oligopeptides and free amio acids composition change during tea processed. As a result, firstly, withering was the vital step for oligopeptide enrichment, followed by fermentation, yellowing and drying. Secondly, as the enrichment of oligopeptides was often accompanied by the increase of protein amino acids, suggesting certain proteins degradation in fresh leaves could be the main source of oligopeptides. Thirdly, a total of 166 abundant oligopeptides were screened out, through which 14 high degradation protein were also located by protomic approaching.

Cost-effective and sensitive indicator-displacement array (IDA) assay for quality monitoring of black tea fermentation

Herein, a new indicator-displacement array (IDA) sensor was developed for the quality evaluation of black tea fermentation. On the principle of the reversible covalent binding of phenylboronic acid and catechol, phenylboronic acids were selected as acceptors for targeted binding to polyphenols. Pyrocatechol violet and alizarin red S were used as indicators of the reaction. The IDA sensors have sensitive differential responses to fermented tea samples, achieving an assessment of the fermentation degree with accuracies of 80.39–88.00% by support vector machine (SVM). In addition, the key polyphenol components of the fermentation process were accurately predicted by the IDA and SVM regression with ratio of prediction to deviation values of 1.55–1.72, 2.03–2.21, and 2.03–2.08 for total polyphenols, total catechins, and epigallocatechin-3-O-gallate, respectively. In conclusion, the developed IDA sensor is capable of the in-situ quality monitoring of black tea fermentation, with the advantages being cost-effectiveness, sensitivity, and rapidity.

Advanced sensing of volatile organic compounds in the fermentation of kombucha tea extract enabled by nano-colorimetric sensor array based on density functional theory

Volatile organic compounds (VOCs) released by food serve as monitoring indicators during fermentation. Thus the demand for highly sensitive and selective biosensors to VOCs is increasing. The current work proposed a novel nano-colorimetric sensor array (nano-CSA) composed of nano-chemo-responsive materials (CRMs) to quantify volatile alcohols (VAs) in the kombucha tea extract fermentation process. The density-functional theory results suggest that CRMs sensitive to VAs have small energy level differences. The higher the energy of the substance itself, the greater the density of the electron cloud and the stronger the reactivity. The higher the binding energy value, the more stable the molecule structure. The larger the angle and the shorter the centroid distance between CRMs and VAs, promote their effective integration. The work confirmed that the CRM-based nano-CSA is crucial in differentiating VAs employed to evaluate the kombucha tea extract fermentation degree with a 98.99% of variance contribution rate by principal component analysis.

Metabolic Fate and Expectation of Health Benefits of [U-<sup>14</sup>C]-Sucrose Inhibited from Digestion Using <i>Morus alba</i> Leaf Extract

Morus alba leaf extract (MLE), a strong inhibitor of sucrase, suppresses blood glucose elevation following sucrose ingestion. To investigate that sucrose inhibited from digestion using MLE is utilized through gut microbiota, [U-14C]-sucrose solutions with or without MLE were administered orally to conventional and antibiotic-treated rats, and the excretion of 14CO2 and H2 produced by gut microbiota was measured for 24 h. After an administration of [U-14C]-sucrose to conventional rats, the unit excreted 14CO2 peaked at 4 h, and the cumulative 14CO2 excreted over 24 h was approximately 60% of the radioactivity administered. No H2 was excreted. Following an administration of [U-14C]-sucrose and MLE in conventional rats, the unit excreted 14CO2 peaked later, at 8 h, and was significantly lower (p<0.05). The cumulative 14CO2 excreted over 24 h was equal in both groups, although there was a time lag of 2-3 h in rats given [U-14C]-sucrose and MLE. The amount of H2 excreted by these rats peaked 8 h after administration. Following the administration of [U-14C]-sucrose and MLE to antibiotic-treated rats, the unit excreted 14CO2 peaked lower, and the cumulative 14CO2 excretion over 24 h was approximately 40%. In this group, H2 was minimally excreted. H2 and 14CO2 produced by gut microbiota were excreted simultaneously. In conclusion, sucrose inhibited from digestion using MLE was fermented spontaneously by gut microbiota and was not excreted into feces. In addition, it confirmed that H2 excretion could be used directly to indicate the degree of fermentation of nondigestible carbohydrates.

Nutritional Values and In Vitro Fermentation Characteristics of 29 Different Chinese Herbs

The present study evaluated the nutritional values and in vitro fermentation characteristics of 29 different Chinese herbs in order to develop effective feed additives for livestock nutrition. The Chinese herbs were analyzed for their chemical composition. The in vitro fermentation characteristics were evaluated using the gas production technique with swine cecal chyme inoculum. The results showed that the Allium tuberosum Rottl (Semen allii tuberosi, SAT) had the highest gross energy (GE), crude protein (CP), ether extract (EE), and total amino acid (TAA) contents, whereas Anemones raddeanae Rhizoma (Agstache rugosus, AR) had the highest crude fiber, neutral detergent fiber, and acid detergent fiber contents compared with the other Chinese herbs. The Rhus chinensis Mill (Chinese gall, CG), Scrophularia ningpoensis Hemsl (Radix scrophulariae, RS), Punica granatum L (Punica granatum L, PGL), Atractylodes macrocephala Koidz (White atractylodes rhizome, WAR), Sanguisorbae radix (Garden burnet, GB), Anemarrhena asphodeloides Bunge (Rhizoma anemarrhenaw, RA), and Rhei radix Et Rhizoma (Rheum officinale, RO) had a higher non-fiber carbohydrate content than the other Chinese herbs. The in vitro fermentation kinetic analysis showed that the RS, WAR, and RA had a higher gas production, a theoretical gas production, and a fractional rate of gas production than the other groups. Furthermore, the RA, WAR, RS, and Crataegi fructus (Crataegus pinnatifida Bun, CPB) had a higher total short-chain fatty acids (SCFAs) concentration, and CPB had the highest acetate concentration, whereas the WAR and RS had higher propionate and butyrate concentrations than the other groups. Moreover, the Isatis indigotica Fort (Folium isatidis, FI) and SAT had higher ammonia-N concentration than the other groups. In summary, among the 29 different Chinese herbs, the SAT had the highest nutritional value, which is reflected in the highest contents of GE, CP, EE, and TAA, whereas the RA, WAR, and RS showed better intestinal fermentation profiles, which is reflected in the higher fermentation degree and suitable SCFAs fermentation pattern. These findings provide a theoretical basis for using Chinese herbs as feed additives or microbial carbon sources in the intestines of animals.

Prediction of Tea Polyphenols, Free Amino Acids and Caffeine Content in Tea Leaves during Wilting and Fermentation Using Hyperspectral Imaging.

The withering and fermentation degrees are the key parameters to measure the processing technology of black tea. The traditional methods to judge the degree of withering and fermentation are time-consuming and inefficient. Here, a monitoring model of the biochemical components of tea leaves based on hyperspectral imaging technology was established to quantitatively judge the withering and fermentation degrees of fresh tea leaves. Hyperspectral imaging technology was used to obtain the spectral data during the withering and fermentation of the raw materials. The successive projections algorithm (SPA), competitive adaptive reweighted sampling (CARS), and uninformative variable elimination (UVE) are used to select the characteristic bands. Combined with the support vector machine (SVM), random forest (RF), and partial least square (PLS) methods, the monitoring models of the tea polyphenols (TPs), free amino acids (FAA) and caffeine (CAF) contents were established. The results show that: (1) CARS performs the best among the three feature band selection methods, and PLS performs the best among the three machine learning models; (2) the optimal models for predicting the content of the TPs, FAA, and CAF are CARS-PLS, SPA-PLS, and CARS-PLS, respectively, and the coefficient of determination of the prediction set is 0.91, 0.88, and 0.81, respectively; and (3) the best models for quantitatively judging the withering and fermentation degrees are FAA-SPA-PLS and TPs-CARS-PLS, respectively. The model proposed in this study can improve the monitoring efficiency of the biochemical components of tea leaves and provide a basis for the intelligent judgment of the withering and fermentation degrees in the process of black tea processing.

Dietary citrus pectin drives more ileal microbial protein metabolism and stronger fecal carbohydrate fermentation over fructo-oligosaccharide in growing pigs.

Fructo-oligosaccharide (FOS) and pectin are known soluble dietary fibers and can influence gut microbiota and consequently modulate gut health. To understand the differential impact patterns of pectin vs. FOS in modulating gut microbiota in the small and large intestine, an ileal-cannulated pig model was adopted to compare the temporal and spatial effects of FOS and citrus pectin (CP) on the gut microbiota. Sixteen terminal ileal-cannulated pigs were randomly divided into 2 groups and fed with a standard diet supplemented with either 3% FOS or 3% CP for 28 d. The CP group and FOS group showed different microbial composition, especially in the feces, with time and location as major factors affecting microbiota in the CP group, and with only location contribution in the FOS group. In the feces, relative to the FOS group, the CP group showed higher abundance of ChristensenellaceaeR-7 group and RuminococcaceaeUCG-010 and lower abundance of Mitsuokella and Olsenella (adjusted P < 0.05), a higher level of short-chain fatty acids and a lower level of lactate at both d 14 and 25 (P < 0.05), and more copy numbers of genes encoding key enzymes related to propionate (mmdA) and butyrate (BCoAT) production and lactate utilization (LcdA) (P < 0.05), indicating a greater degree of microbial carbohydrate fermentation. In the ileum, as compared with FOS, CP increased the bacteria with high capability of fermenting amino acids, including Escherichia-Shigella and Klebsiella (adjusted P < 0.05), and the expression of enzymes responsible for amino acid fermentation (i.e. lysine decarboxylase), as well as the amino acid fermentation products (cadaverine and tyramine) (P < 0.05), indicating a greater degree of amino acid fermentation. Overall, our results highlight a differential dynamic impact of dietary CP vs. FOS on microbial composition and metabolism in the gut. The dietary CP has a stronger ability to promote microbial amino acid fermentation in the ileum and carbohydrate fermentation in the feces than FOS. These findings provide a new insight into the role of different fibers in gut nutrition and guidelines for the choice of fibers in manipulating gut health.

An in-depth multiphasic analysis of the chocolate production chain, from bean to bar, demonstrates the superiority of Saccharomyces cerevisiae over Hanseniaspora opuntiae as functional starter culture during cocoa fermentation

Hanseniaspora opuntiae is a commonly found yeast species in naturally fermenting cocoa pulp-bean mass, which needed in-depth investigation. The present study aimed at examining effects of the cocoa isolate H. opuntiae IMDO 040108 as part of three different starter culture mixtures compared with spontaneous fermentation, regarding microbial community, substrate consumption, and metabolite production dynamics, including volatile organic compound (VOC) and phytochemical compositions, as well as compositions of the cocoa beans after fermentation, cocoa liquors, and chocolates. The inoculated H. opuntiae strain was unable to prevail over background yeasts present in the fermenting cocoa pulp-bean mass. It led to under-fermented cocoa beans after four days of fermentation, which was however reflected in higher levels of polyphenols. Cocoa fermentation processes inoculated with a Saccharomyces cerevisiae strain enhanced flavour production during the fermentation and drying steps, which was reflected in richer and more reproducible aroma profiles of the cocoa liquors and chocolates. Sensory analysis of the cocoa liquors and chocolates further demonstrated that S. cerevisiae led to more acidic notes compared to spontaneous fermentation, as a result of an advanced fermentation degree. Finally, different VOC profiles were found in the cocoa beans throughout the whole chocolate production chain, depending on the fermentation process.

Freeze-thaw condition limits the fermentation process and accelerates the aerobic deterioration of oat (Avena sativa) silage in the Qinghai-Tibet Plateau.

The objective of this study is to determine the effect of freeze–thaw condition on the fermentation characteristics, microbial community, and aerobic stability of oat (Avena sativa) silage in the Qinghai-Tibet Plateau. Oat forage was harvested at milk ripening stage, ensiled in vacuum-sealed bags, and then stored at (1) a constant temperature of 20°C, as a control (20 group) or (2) subjected to freeze–thaw condition (alternating 20 and −5°C every 12 h; S group). The quality and microbial community in the silage were measured after 1, 3, 7, 14, and 60 days of ensiling, and the aerobic stability was measured after 60 days of ensiling at room temperature or at the two treatment temperatures. The results showed that the higher the pH, the lower the concentration of lactic acid and the ratio of lactic acid/acetic acid of the samples under freeze–thaw condition, as compared to those stored at 20°C. The dry matter content of 20 groups was significantly higher than S group (p < 0.05). While ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), and water-soluble carbohydrates (WSC) had no significant difference between two groups. Lactobacillus spp., Leuconostoc spp., and Weissella spp. were the most prevalent bacterial genera in all groups. The abundance of Lactobacillus spp. in the 20 group was the highest on day 3 of ensiling (p < 0.05), and it reached the peak on day 14 in the S group, but the abundance in the S group did not exceed 50% during whole fermentation process. The abundance of Enterobacterales and the count of Escherichia coli in the S group was significantly higher than 20 group (p < 0.05). Interestingly, the lactic acid concentration was significant correlated with Lactobacillus spp. in 20 group, while correlated with Leuconostoc spp. in S group. The aerobic stability of the S group was lower than that of the 20 group (p < 0.05). The present study indicates that the freeze–thaw condition led to insufficient fermentation degree of silage by limiting the fermentation of Lactobacillus spp. and severely reduced the aerobic stability of oat silage.