Microbiomics and metabolomics insights into the microbial regulation on the formation of flavor components in the traditional fermentation process of Chinese Hongqu aged vinegar

This study aimed to investigate microbial succession and metabolic dynamics during the traditional fermentation of Hongqu aged vinegar,and explore the core functional microbes closely related to the formation of flavor components.Microbiome analysis demonstrated that Lactobacillus,Acetobacter,Bacillus,Enterobacter,Lactococcus,Leuconostoc and Weissella were the predominant bacterial genera,while Aspergillus piperis,Aspergillus oryzae,Monascus purpureus,Candida athensensis,C.xylopsoci,Penicillium ochrosalmoneum and Simplicillium aogashimaense were the predominant fungal species.Correlation analysis revealed that Acetobacter was positively correlated with the production of tetramethylpyrazine,acetoin and acetic acid,Lactococcus showed positive correlation with the production of 2-nonanone,2-heptanone,ethyl caprylate,ethyl caprate,1-hexanol,1-octanol and 1-octen-3-ol,C.xylopsoci and C.rugosa were positively associated with the production of diethyl malonate,2,3-butanediyl diacetate,acetoin,benzaldehyde and tetramethylpyrazine.Correspondingly,non-volatile metabolites were also detected through ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry.A variety of amino acids and functional dipeptides were identified during the traditional brewing of Hongqu aged vinegar.Correlation analysis revealed that Lactobacillus was significantly associated with DL-lactate,indolelactic acid,D-(+)-3-phenyllactic acid,pimelic acid,pregabalin and 3-aminobutanoic acid.This study is useful for understanding flavor formation mechanism and developing effective strategies for the suitable strains selection to improve the flavor quality of Hongqu aged vinegar.

Fermentation characteristics of vinegar residue and some natural materials

Solid state fermentation is an attractive process to produce cellulase economically due to its lower financial investment and lower operating costs. Generally available natural materials in our study included vinegar residue, wheat bran, rice bran and wheat straw. Cellulase production was carried out by solid state fermentation using these materials as the substrate of Trichoderma koningii. The ingredients of natural materials, associated with the effects of water content, time and nitrogen sources on cellulase synthesis were studied. A comparatively high cellulase activity （〉4 IU·g^-1 SDM） was obtained in the fermentation batch. The optimum culture time of vinegar residue, wheat bran and wheat straw were 72 hours, but that office bran was 60 hours. Total water contents of wheat bran, rice bran and wheat straw should not exceed 50% and that of vinegar residue should not be more than 60%. It was also shown that nitrogen salts contributed much to fermentation. （NH4）3PO4 and urea achieved good results in promoting enzyme activity.

Upgrading the Fermentation Process of Zhejiang Rosy Vinegar by Purebred Microorganisms

Purebred microorganisms were employed to upgrade the fermentation process of Zhejiang rosy vinegar. The fermentation cycle was greatly shorten from 5 months to 72 d. The transformation rate of raw materials was increased from 1:4.5 in the traditional fermentation to 1:5 or more in the upgraded fermentation. The content of organic acids in the traditional vinegar (TRV), the upgraded vinegar (UPV) and the submerged fermentation vinegar (SFV) were also investigated by HPLC. No significant difference was found regarding the proportion of phenylethanol to the total volatile components in UPV (7.47% ± 0.00324%) and TRV (7.23% ± 0.00329%), but it was significantly higher than that in SFV (2.26% ± 0.00143%). This study provides deep insight into upgrading the fermentation process of Zhejiang rosy vinegar by purebred microorganisms.

Optimization of Acetic Acid Fermentation Process of Apple Cider Vinegar

This paper studied the fermentation rules of apple cider vinegar from fruit juice,to provide a theoretical guidance for the production of apple cider vinegar.Using Fuji apples as raw materials,the process parameters(fermentation temperature,fermentation time,stirring speed,and inoculation amount)of apple cider vinegar fermentation were optimized through single-factor experiments and response surface analysis.The results indicated that the fermentation temperature had no significant effect on the total acid content of apple cider vinegar fermentation,the fermentation time had an extremely significant effect on the total acid content of apple cider vinegar fermentation,and the stirring speed and inoculation amount had a significant effect on the total acid content of apple cider vinegar fermentation.Through process optimization,the optimal process parameters for apple cider vinegar fermentation are fermentation temperature of 33℃,fermentation time of 39 h,stirring speed of 1500 r/min,and acetic acid bacteria inoculation amount of 7%.Under such conditions,the total acid content of fermented apple cider vinegar is 62.22 g/L,very close to the predicted value of the model,indicating that the process parameters of acetic acid fermentation obtained by response surface methodology(RSM)optimization are reliable and can be used for actual production prediction.

Lactobacillus fermentum as a new inhibitor to control advanced glycation end-product formation during vinegar fermentation

The inhibitory activity of lactic acid bacteria(LAB)toward advanced glycation end-products(AGEs)during vinegar fermentation was studied,and its relationships with the substrate consumption,antioxidant capacity,total phenolic content,total flavonoid compounds,α-glucosidase,andα-amylase activity inhibition were evaluated.The vinegar was made from rice powder flour by liquid-state fermentation(LSF).The selected LAB strains were separately co-cultivated with Saccharomyces cerevisiae and Acetobacter pasteurianus 1.41 in alcoholic and acetic acid fermentation,respectively.Among 3 strains,Lactobacillus fermentum showed the strongest inhibitory effect on the formation of total fluorescent AGEs and carboxymethyl lysine(CML)/carboxyethyl lysine(CEL)in the fermentation process.The corresponding mechanisms included the acceleration of substrate consumtion,improvement of antioxidant activities,and inhibition ofα-glucosidase andα-amylase.In addition,the fluorescent AGEs and the CML/CEL were negatively correlated with the antioxidant activities,while theα-glucosidase andα-amylase activities were positively correlated with the total phenols and total flavonoids.Moreover,the variety of main flavor compounds increased,including esters,alcohols,phenols and acids.The results of the study support the potential use of screened LAB strains to inhibit the formation of fluorescent AGEs,CML and CEL on fermented products and in the food processing industry,without associated risks to consumers.

Study on the Saccharification Process of Citrus Vinegar by Fruit-Grain Mixed Fermentation

This study aimed to enhance acid production rate and yield of citrus vinegar, and improve the quality of liquid fermented with fruit juice. [ Method] The saccharification process of citrus vinegar was investigated preliminarily with fruit-grain mixed fermentation method using liquor starters as saccharif- erous agents. [Result] The results indicated that the optimal glutinous rice saccharification conditions were as follows： fruit-grain ratio 3： 1, Aspergillus niger- Monascus purpureus ratio 3： 1, saccharifieafion temperature 60℃, and saccharification time 2.5 h. Under the optimized saccharification conditions, reducing sugar content in saceharified glutinous rice reached 146.43 mg/ml; after fermentation, alcohol content in fermentation broth was 6%, amino nitrogen content was 0.44 mg/ml, and acid yield was 3.1 g/L. [ Conclusion] Citrus vinegar brewed based on the optimized technological conditions exhibited better sensory and physico-chemical properties than that brewed with pure juice.

Screening of Acetic Acid Producing Microorganisms from Decomposed Fruits for Vinegar Production

Acetic acid bacteria capable of growing at 30&#176C - 37&#176C were collected from various decomposed fruits available in Bangladeshi local markets in order to assess their suitability for vinegar production. Initially, 42 microorganisms were isolated from decomposed fruits like grapes, mangoes, pineapples, oranges, safeda etc. during summer when temperature reaches up to 37&#176C. Then their growths were checked in YPG medium containing various ethanol concentrations at different time point at 37&#176C. From the preliminary screening, 15 Gram negative bacterial isolates have produced halos or yellow zone around the colonies on YPG agar plate at 37&#176C which indicated acetic acid production capability by those bacteria. Furthermore, acetic acid production rates were determined by titration method and about 3 - 6.9 gm/100ml acetic acid were estimated by using 4% ethanol at 37&#176C by shaking culture for 3 days. Several biochemical analysis revealed that our collection contained huge amount of acetic acid producing bacteria and some of them could be potential candidates for vinegar production.

Microbial metabolic interaction in fermentation ecosystem and cooperation in flavor compounds formation of Chinese cereal vinegar

Shanxi aged vinegar(SAV)is a famous cereal vinegar in China,which is produced through a solid-state fermentation where diverse microbes spontaneously and complex interactions occur.Here,combined with the metatranscriptomics,the microbial co-occurrence network was constructed,indicating that Lactobacillus,Acetobacter and Pediococcus are the most critical genera to maintain the fermentation stability.Based on an extensive collection of 264 relevant literatures,a transport network containing 2271 reactions between microorganisms and compounds was constructed,showing that glucose(84%of all species),fructose(67%)and maltose(67%)are the most frequently utilized substrates while lactic acid(64%),acetic acid(45%)are the most frequently occurring metabolites.Specifically,the metabolic influence of species pairs was calculated using a mathematical calculation model and the metabolic influence network was constructed.The topology properties analysis found that Lactobacillus was the key role with robust metabolic control of vinegar fermentation ecosystem and acetic acid and lactic acid were the main metabolites with feedback regulation in microbial metabolism of SAV.Furthermore,systematic coordination of positive and negative impacts was proved to be inevitable to form flavor compounds and maintain a natural microbial ecosystem.This study provides a new perspective for understanding microbial interactions in fermented food.

Production of Vinegar Mango Using Acetobacter tropicalis CRSBAN-BVA1 and CRSBAN-BVK2 Isolated from Burkina Faso

Production and quality of vinegar from mango juice was evaluated using a two steps production procedure. The first step of fermentation was done using Saccharomyces cerevisae KVL013 for 7 days. The second step, an acetic fermentation was realized using two acetic acid bacteria: A. tropicalis CRSBAN-BVA1 and A. tropicalis CRSBAN-BVK2 for 21 days. Several parameters of the vinegar produced such as physico-chemical and sensory properties were determined. Microbial density during each step was monitored. Results showed that pH, alcoholic and acetic acid contents of vinegar were respectively 2.97%, 7% and 4.54% g/ml respectively by using A. tropicalis CRSBAN-BVA1 and 3.02%, 7% and 4.32% g/ml with A. tropicalis CRSBAN-BVK2. Sensory evaluation revealed that the vinegar was acceptable to the panellists. Results of microbial density showed that the maximum concentration of cell biomass produced was 4.32 × 108 and 4.25 × 108 CFU/ml respectively for CRSBAN-BVA1 and CRSBAN-BVK2.

醋醅源非酿酒酵母的鉴定及其对葡萄酒品质的影响

为改善传统商业酿酒酵母酿造葡萄酒的风味与口感,以醋醅中分离的菌株JM为研究对象,对其进行形态学观察、分子生物学鉴定和耐受性分析;以菌株JM、商业酿酒酵母(SC)和安琪活性生香干酵母(ADY)单菌及混菌发酵酿造葡萄酒,并对其品质进行分析。结果表明,经鉴定,菌株JM被鉴定为扁平云假丝酵母(Candida humilis),在发酵液中总酯产量为2.64 g/L,其可耐受3.0%柠檬酸、温度35℃、体积分数6%的乙醇及4%NaCl。在不同组别葡萄酒样品中,JM+SC混菌制备的葡萄酒品质最佳,其酒体颜色为紫红色,L*值、a*值、b*值分别为53.93、20.38、4.85;糖度为7°Bx,总酸含量为3.38 g/L,还原糖含量为22.00 g/L,pH为3.58,花色苷含量为205.52 mg/L,酒精度为12.60%vol,总酯含量为1.47 g/L;1,1-二苯基-2-三硝基苯肼(DPPH)、2,2'-联氮-双(3-乙基苯并噻唑啉-6-磺酸)(ABTS)自由基清除率分别为42.21%、32.86%;酒样富含丙酸乙酯和乙酸戊酯,果香浓郁,清爽可口,具备酿造高品质葡萄酒的潜力。

甘草柑橘皮果醋发酵工艺研究

以柑橘皮为主料,甘草为辅料,采用液态发酵法制备甘草柑橘皮果醋。先以总黄酮含量为指标,在单因素试验的基础上通过响应面法优化酒精液制备工艺;再在最佳酒精液制备条件下,以总酸含量和感官评分为指标,通过响应面法优化果醋制备工艺,并对其理化及微生物指标进行分析。结果表明:酒精液最佳工艺参数为酵母菌接种量0.5%(以原料液体积为基准)、原料液糖度16%、发酵时间9 d,在此条件下果醋总黄酮含量为5.37%。最佳果醋制备参数为醋酸菌接种量2.0%(以酒精液体积为基准)、发酵温度35℃、初始乙醇体积分数8.5%、发酵时间9 d,在此条件下果醋总酸含量为5.61 g/100 mL,感官评分为8.74,微生物指标符合相关标准要求。

发酵型茶醋的品质分析及抑菌性

以广西贺州生产的红茶(迎霜、月湾)、绿茶(开山白毛、茗山)为原料,分别与新鲜甘蔗汁混合发酵制备茶醋,考察其醋酸发酵过程中的色差、总酸、茶多酚、茶氨酸、总黄酮等指标变化,并通过电子鼻测定茶醋整体特征气味轮廓,同时采用牛津杯‐琼脂法分析4种茶醋对大肠埃希氏菌、金黄色葡萄球菌、白色念珠菌3种致病菌的抑菌效果。结果显示,绿茶(开山白毛、茗山)发酵体系的产酸能力较强,且茶多酚含量较高,茶醋中总黄酮成分保留较好;酸类、醇类、芳香化合物、烷类物质是茶醋的整体特征气味轮廓;以抑菌圈的大小判断4种茶醋的抑菌效果发现4种茶醋对大肠埃希氏菌、金黄色葡萄球菌、白色念珠菌都有一定的抑菌效果,抑菌圈明显,且茗山茶醋抑菌效果最佳,其对3种致病菌的抑菌作用为高敏感。不同茶叶品种发酵的茶醋品质和抑菌效果都有明显差别,但绿茶发酵的茶醋的口感比红茶发酵的茶醋丰富,且茶香、醋香味较为明显。

添加部分水解罗望子胶对酸木瓜果醋品质的影响

该研究以酸木瓜(Chaenomeles speciosa)为原料,通过部分水解罗望子胶(PHTG)对6株乳杆菌的增殖活性测定,选用鼠李糖乳杆菌(Lactobacillus rhamnosus)与酵母菌混菌进行酒精发酵,并从灵石醋醅中筛选鉴定出一株高产醋酸的巴氏醋杆菌巴士亚种(Acetobacter pasteuranus subsp. pasteuranus)LS-4用于醋酸发酵制备酸木瓜果醋。以未添加PHTG为对照,考察在酒精发酵阶段添加PHTG对酸木瓜果醋品质的影响。结果表明,添加1.0%PHTG,酒精发酵36 h后酒精度达3.3%vol,比对照组提高17.4%;醋酸发酵72 h后总酸含量达42.0 g/L,比对照组提高8.0%。香气成分分析表明,添加PHTG酸木瓜果醋共检出22种香气成分,其中醇类7种、酯类4种、酸类6种、醛酮类3种、酚类和烯烃类各1种,比对照新增了3种香气成分(正丁酸、2-戊酮和壬醛)。感官评价表明,添加PHTG有效提升酸木瓜果醋的口感和气味评分,改善酸木瓜果醋的感官品质。

金银花提取液对苹果醋发酵过程中理化指标及品质的影响

为开发功能性金银花复合果醋,该研究分析了5种不同浓度金银花提取液发酵苹果醋过程中CO_(2)释放量、总酸含量、总酚含量、DPPH自由基清除率、主要有机酸含量等理化品质指标。结果表明,当金银花提取液添加量为20%时,以CO_(2)释放量表示的发酵速率比对照组提高了20.75%,总酸含量为35.8 g/L,总酚含量为5.83 mg/mL,DPPH自由基清除率为78.78%,绿原酸含量为256.43μg/g FW,与对照组相比,有效提高了苹果醋的综合品质。

苹果幼果-红薯复合果粮醋发酵工艺优化及品质分析

文章以苹果幼果与红薯为原料,采用单因素试验与响应面试验确定苹果幼果-红薯复合果粮醋醋酸发酵的最佳工艺;在此基础上,比较分析发酵前(苹果幼果-红薯复合果粮汁)、发酵后(苹果幼果-红薯复合果粮醋)以及市售苹果醋的抗氧化能力;采用顶空固相微萃取-气相色谱-质谱联用法(HS-SPME-GC-MS)检测发酵前(苹果幼果-红薯复合果粮汁)、发酵后(苹果幼果-红薯复合果粮醋)以及市售苹果醋的挥发性风味物质。结果表明,醋酸发酵的最佳工艺为醋酸菌接种量10%、初始酒精度7%、发酵温度31℃。与苹果幼果-红薯复合果粮汁、市售苹果醋相比,苹果幼果-红薯复合果粮醋具有较强的抗氧化能力,挥发性风味物质更丰富,酸类、酯类物质的种类和含量显著更高。该研究可为苹果幼果-红薯复合果粮醋的开发提供数据支撑。

酵母菌混合发酵乳清液及其乙醇发酵阶段工艺优化

选择马克斯克鲁维酵母CGMCC13907(以下简称马氏酵母CGMCC13907)和酿酒酵母AS2.119为混合发酵剂发酵乳清液制备乳清醋,并采用Plackett-Burman Design(PBD)和Box-Behnken Design(BBD)试验优化乙醇发酵阶段的工艺。结果表明:乙醇发酵阶段的最优工艺为马氏酵母CGMCC13907接种量4.0×10^(6) CFU/mL,酿酒酵母AS2.119接种量4.5×10^(6) CFU/mL,发酵时间151 h,发酵温度40.0℃,发酵pH值5.6,姜粉用量0.09 g/100 mL,在此条件下,发酵液中乙醇浓度可达8.70%vol,比优化前增加了56.2%。因此,选用马氏酵母CGMCC13907结合酿酒酵母AS2.119混合发酵乳清液,可有效解决乳清醋制作过程中的乳糖发酵难题,并获得较理想的乙醇浓度。

多菌种混合发酵神农架猕猴桃果醋的工艺优化及风味分析

以神农架猕猴桃为原料,通过多菌种混合发酵制备猕猴桃果醋。通过单因素及正交试验优化其酒精、醋酸发酵工艺条件,采用氨基酸分析仪及气质联用(GC-MS)技术分别分析果醋的氨基酸、挥发性风味物质组成。结果表明,最佳酒精发酵工艺为:酵母菌接种量0.9%,乳酸菌接种量7%,初始可溶性固形物19°Bx,发酵温度27℃。在此优化条件下,酒精度为(8.82±0.57)%vol,乳酸含量为(12.15±0.73)mg/mL。最佳醋酸发酵工艺为:发酵时间8 d,醋酸菌接种量12%,初始酒精度7%vol,发酵温度32℃。在此优化条件下,醋酸含量为(4.34±0.17)g/100 mL,感官评分为80分。多菌种混合发酵猕猴桃果醋共检出15种氨基酸,包含7种必需氨基酸;共检出37种挥发性风味物质,包括酯类17种,酸类5种,醛类2种,酮类5种,苯类2种,醇类4种,酚类1种,其他类1种。综上,多菌种混合发酵有利于促进氨基酸和挥发性风味物质的形成,从而提升果醋的品质。

响应面法优化荞麦食醋酒精发酵工艺

为了提高荞麦食醋发酵过程中酒精发酵阶段的乙醇产量,以发酵醪酒精度为响应值,以固液比、酵母接种量、接种温度、发酵温度、发酵时间等因素为自变量,利用单因素结合响应面试验,优化荞麦醋酒精发酵工艺条件。结果表明,最佳酒精发酵工艺为固液比1∶4(g∶mL)、酵母接种量30%、酵母接种温度30℃,发酵温度28℃,发酵时间7 d。在此优化条件下,酒精度为9.52%vol,比优化前(8.51%vol)提高了11.9%。

刺梨果醋发酵过程中理化特性和风味特征的变化

为探究刺梨果醋发酵过程中成分变化,本文以刺梨为原料,采用全液态发酵技术,经酒精发酵和醋酸发酵制备果醋,动态监测发酵过程中的理化特性,并采用固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase microextraction-gaschromatography-mass spectrometry,HS-SPME-GC-MS)和气味活性值(Odoractivityvalue,OAV)分析挥发性风味成分。结果表明,随着发酵时间的进行,可溶性固形物、pH、总糖及还原糖均呈下降趋势,而总酸和V_(C)含量持续增加,由原汁到醋酸发酵结束分别从1.86 g/100 mL和956.82 mg/100 mL增加至6.79 g/100 mL和1275.88 mg/100 mL。有机酸的含量不断变化,草酸、奎宁酸、丙酮酸、抗坏血酸、乳酸、乙酸及富马酸呈现不同程度的显著增加(P<0.05),而甲酸、柠檬酸、马来酸和琥珀酸含量变化小。共检测到92种挥发性物质,结合OAV分析,10种挥发性物质被确定为刺梨果醋中OAV≥1的关键香气物质,即壬醛、乙醛、异丁酸乙酯、丁酸乙酯、2-甲基丁酸乙酯、乙醇、异戊醇、叶醇、芳樟醇及苯乙醇。其中,丁酸乙酯和叶醇对刺梨果醋香气贡献最大,是刺梨果醋具有青草香、青苹果香的特征风味物质。研究结果为有效控制发酵条件、揭示发酵刺梨果醋的理化特性和风味特征,形成刺梨果醋品质评价方法、制定质量标准提供理论基础和实践指导。

板栗醋发酵工艺优化及挥发性成分分析

为提高板栗资源利用率,开发板栗深加工产品,以板栗为原料,通过酒精和醋酸发酵,研究开发一款新型板栗醋。以感官评价和酸度的综合评分为评价指标,采用单因素和正交试验对板栗醋进行工艺优化。结果表明,酒精发酵优化后工艺条件为酒精发酵温度22℃、酵母菌添加量0.04%、初始糖度17°Brix、酒精发酵时间5 d;醋酸发酵优化后工艺条件为醋酸发酵温度31℃、果醋菌添加量0.04%、装液量40%、转速170 r/min、醋酸发酵时间8 d,优化后板栗醋总酸20.18 g/L,具有黄色透明质感、板栗果香,味道醇厚。采用顶空固相微萃取(headspace solid phase microextraction,HS-SPME)结合气质联用(gas chromatography-mass spectrometry,GC-MS)测定板栗醋3个发酵阶段的挥发性成分并探究其变化,结果表明,板栗醋3个发酵阶段挥发性成分的含量及种类有明显差异,在板栗浆、酒精发酵和醋酸发酵阶段时,挥发性成分含量最高的分别为乙酸(15.36%)、乙醇(30.26%)和乙酸(41.13%)。