Influence of fermentation oxygen partial pressure on semicontinuous acetification for wine vinegar production

This paper describes semicontinuous acetic acid fermentations for wine vinegar production carried out with different aerating gas compositions ranging from 21% (air) to 63% oxygen content and using low aeration (3.7 h^–1, vvm), in order to study the influence of the oxygen partial pressure on the aerating gas supplied to the reactor in this industrial biotransformation process. The acetification process was conducted in 6- to 100-l reactors. The overall acetic acid productivity increased from 0.72 g l^–1 h^–1 with air to 1.35 g l^–1 h^–1 when oxygen-rich (36%) air was used. The same behaviour was observed for the maximum acetification rate, and therefore the total process time was reduced in proportion to the increase in productivity, from 65 h using air to 35 h using an aerating gas mixture containing 36% oxygen. The yield of the process was high, 96–99%; the final concentration of acetic acid reached was 116–118 g l^–1; and the substrate yield coefficient based on ethanol metabolised was higher using oxygen-rich air than with air. It was not feasible to carry out semicontinuous acetification cycles with an oxygen content higher than 40%, and when the oxygen content was 63%, the process stopped during the first cycle with very little acetic acid production. Moreover, an inverse relationship between the acetic acid formation rate profile in the course of the acetification process and the amount of dissolved acetaldehyde in the fermentation broth formed by the acetic bacteria was observed.     

川南麸醋入池发酵过程中理化指标变化规律研究

连续测定川南某醋厂入池发酵过程中7项理化指标的动态变化。试验结果表明,水分变化不大,从整个周期来看,略有提升;淀粉在整个入池发酵过程中从33.81g/100g干醅降低到26.12g/100g干醅,利用率只有21.71%;还原糖和酒精都是中间代谢产物,发酵过程中不断生成但同时又被消耗利用,都呈先增加后降低的趋势;氨基酸态氮含量一直上升,从0.42g/100g干醅上升到1.14g/100g干醅;不挥发酸和挥发酸为麸醋的主要成分,且一直呈上升趋势,不挥发酸最高含量达到8.99g/100g干醅(以乳酸菌计),挥发酸最高含量达4.71g/100g干醅(以乙酸计)。研究发现,川南麸醋入池发酵过程可分成3个阶段,其中0~1d主要为糖化、酒化、醋化阶段,2~7d主要为酒化、醋化阶段,还有缓慢的糖化作用,8~13d主要是醋化阶段。由于是生料发酵,川南麸醋入池发酵阶段存在明显的淀粉利用率偏低的现象。     

Analysis of organic acids in Chinese raisin tree (Hovenia dulcis) peduncle and their changes in liquid fermentation process

Chinese raisin tree (Hovenia dulcis) peduncle is a wonderful food material for fermented food for high contents of sugars and a variety of organic acids. The organic acids in the fresh peduncle, fermented wine, and vinegar were identified and quantified by HPLC, and changes in biochemical parameters and organic acids in the fermentation process were studied. Skin-on fermentation was carried out in the alcoholic fermentation, and 9 identified organic acids fluctuated by physical or biochemical reactions during the alcoholic fermentation. Submerged fermentation was carried out in the acetic fermentation. It took 72 h to finish the 1^st cycle of acetification with the titratable acidity 5.42%(w/v), and 30 h to finish the 2^nd cycle. The contents of acetic acid, formic acid, and α-ketoglutaric acid increased, while the rest identified organic acids decreased in the acetification process. The fermentation developed in this study appeared to be a practical processing method for Chinese raisin tree peduncles.     

Evolution of the antioxidant capacity and phenolic contents of persimmon during fermentation

The changes in antioxidant capacity and phenolics of persimmon during alcoholic fermentation, acetification, and short aging were investigated. An increase in the antioxidant activity was observed when persimmon was transformed from puree to vinegar. The total content of phenolics remained stable, in contrast to the concentration of condensed tannin, which significantly (p < 0.05) increased during alcoholic and acetic fermentations, although followed by a decrease after aging. The phenolic compounds were characterized and quantitated. Gallic acid was the main phenolic compound, and its content increased by 14.4% during alcoholic fermentation and reduced by 53.5% during acetic fermentation. Additionally, the flavan-3-ol compounds increased during alcoholic fermentation and acetification. Vanillyl alcohol, (?)-epigallocatechin, and p-coumaric acid were not observed in persimmon puree but detected in persimmon wine and vinegar. These results indicate that alcoholic and acetic fermentation can improve the antioxidant capacity of persimmon fruit.     

樱桃醋饮料的研制

以樱桃果酒发酵之后的下脚料为原料,酿制具有营养保健作用的樱桃醋。由正交试验得醋酸发酵的工艺条件为：发酵温度30℃、时间230h、酒精含量8.5%、糖度5°Bx、接种量10%;樱桃醋饮料的最佳配方为：樱桃醋5ml、柠檬酸0.15g、乳酸钙0.15g、蔗糖9g、水100ml。     

黑枸杞果醋发酵工艺条件优化

以黑枸杞干果为原料制备黑枸杞果醋,通过单因素试验、正交试验与响应面试验,确定黑枸杞果醋酒精发酵和醋酸发酵的最佳工艺条件。结果表明,最适于酒精、醋酸发酵的菌种分别为葡萄酒果酒酵母、沪酿1.01醋酸菌。酒精发酵的最佳工艺条件为：黑枸杞干果添加量为15%,初始糖度17%、发酵温度32 ℃、接种量4%;醋酸发酵的最佳工艺条件为：发酵温度30 ℃、接种量7%、装液量42 mL/250 mL。在此优化条件下,黑枸杞果醋的酸度为3.76 g/100 mL,花青素含量为0.55 g/100 mL。黑枸杞果醋饮料色泽深紫、酸度适中,具有浓郁的果醋香和黑枸杞的清香。     

A protocol for optimization vinegar fermentation according to the ratio of oxygen consumption versus acid yield

Fermentation rate and fermentation efficiency are two key aspects for industrial vinegar production. A new target, ratio of oxygen consumption versus acid yield, is introduced to evaluate the fermentation efficiency. Semi-continuous fermentation is optimized by means of harmony between acetification rate and ratio of oxygen consumption versus acid yield. This protocol operates on initial acidity of discontinuous procedure to adjust bacterial metabolism which directly affects the fermentation process. As a result, average acetification rate is increased to 1.81 g acid/l h, which is 20% higher than the original level (1.48 ± 0.32 g acid/l h), and the air flow rate is also reduced by 41% of initial setting. In such a condition, the stoichiometry yield of vinegar is also improved to 94.3 ± 0.67%. So this method could be considered to optimize the industrial scale process in future.     

Set Up and Optimization of a Laboratory Scale Fermentor for the Production of Wine Vinegar

A laboratory scale fermenter was used to produce wine vinegar in a submerged culture acetic fermentation. The aim was to establish the optimal experimental conditions for three important acetification factors in order to obtain high concentrations of acetic acid within the shortest period of time. These factors were stirring speed, substrate loading and working volume. The effect of each single factor taking part in the process and the effect of the possible interaction among these was evaluated. For this purpose an experimental factorial design with a multiple linear regression (MLR) model resolved with a CSS‐Statistics programme was applied. The results indicate that to obtain a high fermentation yield the stirring speed was the most important factor and the loading proportion the most important factor to achieve a better rate of acetification.     

五味子果醋的研制

以分离筛选的醋酸菌HAc-5为发酵菌种,发酵五味子干酒制备成五味子果醋。醋酸发酵于163h时达到峰值,总酸度为10.363g/100mL,醋酸的转化率为98.11%。制备成的五味子果醋色泽黄而微红,半透明,酸味醇厚丰满,微涩,具有五味子独特的药味香气,并可开发成具有保健功能性的果醋饮品。     

Optimization and scale-up of L-lactic acid fermentation by mutant strain Rhizopus sp. MK-96-1196 in airlift bioreactors

We determined the optimum culture conditions such as inoculum size, initial starch concentration, pH during the fermentation and aeration rate for L-lactic acid production by Rhizopus sp. MK-96-1196 in a 3-l airlift bioreactor. More than 90 g/l of L-lactic acid was produced from only partially enzymatically hydrolyzed corn starch with a production rate of 2.6 g/l/h and a product yield of 87% based on the starch consumed under the optimum conditions in the 3-l airlift bioreactor. Scale-up from the 3-l to a 100-l airlift bioreactor for L-lactic acid fermentation was carried out using V(s)(cm/s) as a scale-up criterion. The production rates and yields of L-lactic acid in both bioreactors appeared to be fairly well correlated with k(L)a (1/h).     

桤叶唐棣果醋发酵工艺优化及有机酸和挥发性成分分析

以桤叶唐棣为原料,经半固态发酵酿制桤叶唐棣果醋,以总酸作为评价指标,优化桤叶唐棣果醋发酵工艺,并对发酵前后有机酸和挥发性成分进行比较。结果表明,最佳发酵条件为初始酒精度9%vol,果酒与果渣质量比1.0:1.6,醋酸菌添加量2.0%,在30 ℃条件下发酵18 d,测得桤叶唐棣果醋总酸含量为4.75 g/100 mL。桤叶唐棣果醋中以醋酸（5.00 mg/mL）、丙二酸（0.41 mg/mL）、乳酸（0.25 mg/mL）为主。主要挥发性物质为3-羟基-2-丁酮（15.86%）、乙酸（35.62%）、乙酸乙酯（24.32%）、苯甲醇（17.60%）、苯甲酸（6.60%）。     

液态深层发酵制醋新工艺的探索

通过对液态深层发酵制醋的菌种、通风量、温度、浓度，流加酒精的时机、方法及剩余酒精的浓度与发酵进程的控制等进行试验，寻找最适条件，确定新的液态醋发酵工艺路线。结果表明：采用新的生产醋工艺，发酵30h-32h，能生成总酸8．0g／100mL，58h-62h，能生成总酸11g／100mL；可以减少菌种传代次数，缩短发酵时间，减少酒精挥发量，提高粮食利用率，降低原料成本和能源消耗。     

燕麦苹果复合果醋发酵工艺优化及其抗氧化活性

以苹果和燕麦为原料,经酒精发酵得到复合果酒,以其为基酒进一步制备燕麦苹果复合果醋,通过单因素和响应面优化燕麦苹果复合果醋的醋酸发酵工艺,并利用2,2'-联氮双（3-乙基苯并噻唑啉-6-磺酸）二铵盐（ABTS）法和1,1-二苯基-2-三硝基苯肼（DPPH）法评价燕麦苹果复合果醋中黄酮类物质抗氧化活性,采用气相色谱质谱联用（GC-MS）分析燕麦苹果复合果醋主要黄酮类物质。结果表明,燕麦苹果复合果醋的最佳醋酸发酵条件为醋酸菌接种量7%（V/V）、发酵温度31 ℃、转速170 r/min、初始酒精度9%vol。此优化条件下,果醋的总酸含量可达（7.35±0.04） g/100 mL;其黄酮类物质抗氧化能力值为（100.27±3.53） mgVCE/L,DPPH自由基清除率可达（60.21±1.56）%,有较高的抗氧化活性;燕麦苹果复合果醋主要黄酮类物质为木犀草素、山柰酚及槲皮素。     

原汁青梅果醋酿造技术研究

本实验分析了不同成熟度青梅的品质,研究了果胶酶处理对出汁率的影响,进行了耐高酸醋酸菌的驯化和原果醋的澄清处理实验,结果认为原汁青梅果醋的适宜加工原料成熟度为8成熟;采用200mg/kg果胶酶处理可使其出汁率提高12.0%,且大大降低取汁难度;利用CaCO3对青梅原酒进行降酸处理,采取低酸醋酸发酵逐步接种到高酸的方法可驯化醋酸菌,使其最终可直接发酵高酸的青梅原酒;青梅原醋经过100mg/L的果胶酶处理3h后,再用1.4g/L的皂土下胶,可使其透光率达到92%以上。     

Effective onion vinegar production by a two-step fermentation system

A two-step fermentation system combining a repeated batch process using a flocculating yeast with a charcoal pellet bioreactor was developed for onion vinegar production. Juice from the red onion R-3, which contained 67.3 g/l total sugar, was smoothly converted to onion alcohol containing 30.6 g/l ethanol by repeated batch operation using the flocculating yeast Saccharomyces cerevisiae strain IR-2. Stable operation was possible and the maximum productivity was about 8.0 g/l/h. A packed bed bioreactor containing charcoal pellets produced from waste mushroom medium was then applied to continuous onion vinegar production from the onion alcohol. Onion vinegar was successfully produced, with a maximum productivity and acetic acid concentration of about 3.3 g/l/h and 37.9 g/l, respectively. The total acetic acid yield calculated from the amount of sugar consumed was 0.86. The two-step system was operated for 50 d and proved to be competitive with other systems in terms of its high productivity, high acetic acid yield, operational stability and low production costs.     

混合微生物发酵生产啤酒醋及饮料开发

以大麦芽为主要原料,进行啤酒醋发酵,调配制备麦香啤酒醋饮料。优化后的啤酒醋发酵工艺条件为：麦芽糖化后接种啤酒酵母进行酒精发酵,24 h后接种生香酵母,继续发酵4 d,啤酒酵母和生香酵母的添加比例为4∶1;醋酸发酵阶段醋酸菌接种量为10%,30 ℃条件下发酵,发酵结束时啤酒醋酸度为（3.21±0.09） g/100 mL,乙醇含量＜0.05%vol。开发麦香啤酒醋饮料,最佳配方为啤酒醋12%,麦芽汁70%,白砂糖3%,橙色素0.04‰,最终产品的酸度为（0.38±0.07） g/100 mL,糖度为（84.32±0.05） g/L,酸糖比为1∶22。感官评定表明,该方法制备的麦香啤酒醋饮料色泽金黄、澄清透明、酸甜爽口,醋香和麦芽香气浓郁。     

Characterization of membrane bioreactor for dry wine production

Characteristics of yeast growth and ethanol fermentation were examined in membrane bioreactor using a grape juice. After inoculation, batch fermentation was carried out for 24 h. When yeast growth reached the stationary phase, continuous fermentation was initiated. In continuous fermentation, a linear relationship was observed between cell concentration and dilution rate. In single-vessel membrane bioreactor, the cell concentrations of 18.7 g/l and 76.9 g/l (15 and 60 times higher than that of the batch fermentation, respectively) were observed at dilution rates of 0.1 h(-1) and 0.3 h(-1), respectively. The residual sugar concentration was higher than 10 g/l at the dilution rate of 0.1 h(-1), 0.2 h(-1) or 0.3 h(-1), therefore the single-vessel membrane bioreactor was not suitable for producing dry wine (sugar concentration: 4 g/l or less). In the double-vessel membrane bioreactor, it is most suitable to set the recycle ratio at 0.15 for keeping the sugar concentration below 4 g/l. The productivity of dry wine in the double-vessel membrane bioreactor was 28 times higher than that in the batch fermentation.     

葡萄糯米香醋发酵工艺的优化

该研究以葡萄和糯米为原料制备葡萄糯米香醋,以酒精度和感官评分为评价指标,采用正交试验设计优化其酒精发酵工艺条件;以总酸含量和感官评分为评价指标,优化其醋酸发酵工艺条件,并对该产品的挥发性成分、理化指标及感官品质进行分析。结果表明,最佳酒精发酵工艺条件为：葡萄与糯米质量比2∶1、初始糖度23%、葡萄酒高活性干酵母添加量0.22%、发酵温度28 ℃;最佳醋酸发酵工艺条件为：初始酒精度7%vol、醋酸菌（Acetobacter aceti）接种量5%、发酵温度30 ℃。在此优化条件下,葡萄糯米香醋共检出31种挥发性成分,其中醇类7种、醛类3种、酸类7种、酯类13种、苯类1种,总酸、总酯含量分别为4.70 g/100 mL、3.18 g/100 mL,葡萄糯米香醋呈红褐色、澄清透亮,口感醇厚、酸甜柔和,具有浓郁的果香和醋香。     

液态法苹果醋生产动态分析

以富士苹果为原料 ,采用快速液态法生产果醋 ,探讨其酒化和醋酸化规律。结果表明 :原料破碎粒度大小影响酒化的进程 ;采用先低强度后高强度通气相结合方式有利于醋酸化的快速进行。     

秋香梨果醋醋酸发酵工艺优化及抗氧化活性研究

以秋香梨酒为原料,采用沪酿1.01醋酸菌,以总酸含量为指标,利用响应面法优化果醋醋酸发酵工艺,并评价果醋的抗氧化能力。结果表明:秋香梨果醋醋酸发酵的最佳工艺条件为醋酸菌接种量9.4%,发酵时间6d,发酵温度31℃,初始pH 4.5。此条件下得到的果醋色泽金黄,果香醇厚,其总酸含量为54.45g/L。秋香梨酒经醋酸菌发酵后,其DPPH自由基清除率、ABTS自由基清除率和Fe3+还原能力分别提高了21.17%,23.65%,30.23%,表明该果醋具有良好的抗氧化活性。