副产物对运动发酵单胞菌酒精发酵的影响

研究了乙酸、乳酸、糠醛作为酒精发酵副产物 ,对细菌酒精发酵的影响。在发酵培养基中 ,当乙酸浓度为 1 5 g/L ,糠醛浓度为 4g/L时 ,细菌酒精产量开始减少。在乳酸浓度为 0～ 2 g/L的范围内 ,没有观察到其对细菌酒精发酵的抑制作用。运用化学渗透假说 ,对酸在细菌酒精发酵中的抑制作用进行了解释 ,同时对糠醛在细菌酒精发酵中的抑制作用进行了理论探讨     

耐酸性运动发酵单胞菌酒精发酵条件的初步研究

在本实验室保藏的运动发酵单胞菌中 ,通过化学诱变和酸性平板分离 ,得到一株能在pH 4 5时进行酒精发酵的菌株 ,其酒精产量为 6 6 7g/L ,与原菌株在pH 6 5时的 6 6 7g/L相同。研究了种龄、接种量、发酵初始pH和发酵温度对细菌酒精发酵的影响。结果表明 ,在种龄为 12hr,接种量 10 % ,发酵温度 30℃～ 35℃ ,pH 4 5时 ,该菌的酒精产量达到最大为 70 1g/L。     

运动发酵单胞菌酒精发酵糟液的全回流技术

酒精生产会产生大量的酒糟废液,若不适当处理,将会对环境造成严重的污染。文中将细菌酒精发酵废液经过过滤后,代替拌料用水,循环用于酒精生产。回流发酵进行了8批,酒精产量没有降低,体积分数稳定在7.3％左右。发酵液残糖和最终pH也趋于稳定,分别在1.5g/L和4.0上下波动。相对于酵母酒糟回流技术,细菌酒糟回流技术所需的处理过程更简单。而且在回流中,不需要每次都添加氮源,这样可以减少发酵有害物质的积累,有利于实现酒糟滤液全回流。     

酒糟处理方式在细菌酒精全回流发酵中的研究

酒精生产过程中，产生了大量的酒糟废液。若不进行适当处理，将会对环境造成严重的污染。研究了酒糟直接回流、酒糟滤液回流和酒糟离心回流的情况以及不同的营养组合对细茵酒精全回流发酵的影响。结果表明：过滤后的酒糟废液，代替原来的拌料用水，循环用于酒精生产，可以实现酒糟的全回流。在回流发酵进行了八批后，酒精产量稳定在67．1g／L以上，比没有回流时的65．2g／L略有提高。而且在回流中，并不需要每次都添加氮源，这样可以减少发酵有害物质的积累，有利于实现酒糟滤液全回流。     

Fermentation of Soybean Meal Hydrolyzates with Saccharomyces cerevisiae and Zymomonas mobilis for Ethanol Production

Most of the ethanol currently produced by fermentation is derived from sugar cane, corn, or beets. However, it makes good ecological and economic sense to use the carbohydrates contained in by‐products and coproducts of the food processing industry for ethanol production. Soybean meal, a co‐product of the production of soybean oil, has a relatively high carbohydrate content that could be a reasonable substrate for ethanol production after fermentable sugars are released via hydrolysis. In this research, the capability of Saccharomyces cerevisiae NRRL Y‐2233 and Zymomonas mobilis subsp. mobilis NRRL B‐4286 to produce ethanol was evaluated using soybean meal hydrolyzates as substrates for the fermentation. These substrates were produced from the dilute‐acid hydrolysis of soybean meal at 135 °C for 45 min with 0, 0.5%, 1.25%, and 2% H₂SO₄ and at 120 °C for 30 min with 1.25% H₂SO₄. Kinetic parameters of the fermentation were estimated using the logistic model. Ethanol production using S. cerevisiae was highest with the substrates obtained at 135 °C, 45 min, and 0.5% H₂SO₄ and fermented for 8 h, 8 g/L (4 g ethanol/100 g fresh SBM), while Z. mobilis reached its maximum ethanol production, 9.2 g/L (4.6 g ethanol/100 g fresh SBM) in the first 20 h of fermentation with the same hydrolyzate.     

氮源及无机盐对蔗汁酒精发酵的影响

对蔗汁培养基组成对酿酒酵母菌株CICC1308酒精发酵的影响进行了初步研究,结果表明,最佳氮源为尿素,最适浓度为0．05％;除此之外,无需添加其它无机盐。KH2PO4的添加对酵母无毒害作用,但不能提高酒精得率;MgSO4的添加对酵母生长和发酵有一定抑制作用。     

Effect of extraction conditions on the yield, purity and surface properties of sugar beet pulp pectin extracts

The extraction of pectins from sugar beet pulp was carried out in an aqueous acid medium under different conditions using a full two-state experimental design for three extraction parameters (pH, temperature and time). The yields of the extracted pectins ranged from 4.1% to 16.2%. Their contents in pectin constituents were 35.2–76.3% galacturonic acid, 6.8–32.9% neutral sugars, 2.0–4.2% methoxy groups, 0.8–3.8% acetyl groups, and 0.1–0.7% ferulic acid. Moreover, protein residues were present in all the extracts within the range of 0.9–6.8% and varied with the extraction conditions. On high performance size exclusion chromatography, the elution pattern of the acid-extracted pectins showed a wide molar mass distribution consisted of two relatively broad peaks. Their weight-average molar mass values determined by HPSEC-RALLS ranged widely from 20,200 to 90,100 g/mol. Most of the extracted pectins were surface-active, and some of them were quite able to produce and stabilize with effectiveness oil-in-water emulsions. Thus, it was inferred that yield, physico-chemical characteristics and surface properties of acid extracted pectins from sugar beet pulp were influenced by the extraction conditions.     

基因工程方法抗甜菜丛根病病毒育种的研究：（Ⅰ）甜菜坏死黄脉病毒外 …

采用含有甜菜坏互黄脉病毒外壳蛋白（ＢＮＹＶＶ ＣＰ）基因的农杆菌，分别以不同甜菜品系的叶柄、下胚轴及子叶为外植体材料进行基因转化研究。含有ＢＮＹＶＶ ＣＰ基因和卡那抗性筛选基因的农杆菌与甜菜组织不同外植体共培养后，经过诱导分化培养，在含有卡那霉素的培养基上，从叶柄及下胚轴分别直接诱导出抗卡那霉素再生芽，而从子叶上只诱导出紧密型绿色愈伤组织，未分化出不定芽。从叶柄及下胚轴诱导两生芽的诱导培养基分别为     

Effect of chemical treatments of sugar beet fibre on their physico-chemical properties and on their in-vitro fermentation

Chemically treated and dried sugar beet fibres were fermented in vitro in order to study the effects of chemical and physico-chemical parameters of dietary fibre on their colonic fermentation. Sugar beet fibre was treated with dilute alkali, removing mainly acetyl and methyl ester groups, and/or with dilute acids eliminating arabinose, galactose and certain uronic acid residues. The chemical treatments led to an increase in the hydration properties and fermentability by improvement of the accessibility of the remaining polysaccharides. However, if the chemically treated fibres were dried under harsh conditions (100°C), their hydration properties and their fermentability were limited, probably because of structural collapse of the fibre matrix. Whatever the conditions for chemical treatments and drying of the sugar beet fibres, it was possible to predict their fermentability from the water-binding capacity. Because of the relationship between the physiological effects of dietary fibres and the extent to which they are fermented, this result underlines the importance of the physico-chemical characterisation of the fibre in order to acquire a better knowledge of their physiological effects.     

苹果汁中果酸(苹果酸)的分离(Ⅰ)--果酸在LSI-1031阴离子交换树脂上交换吸附行为的研究

研究了苹果汁中果酸在4种阴离子交换树脂上的静态吸附特性,其中LSI-1031阴离子交换树脂对果酸的交换吸附能力最强;系统测定并分析了果酸在LSI-1031阴离子交换树脂上交换吸附静态动力学、吸附等温曲线、动态动力学曲线及影响动态动力学曲线的因素,并确定了果酸交换吸附最佳工艺参数,结果表明:LSI-1031阴离子交换树脂吸附平衡时间为4h;20℃时,LSI-1031阴离子交换树脂吸附等温曲线符合Langmuir型吸附曲线;柱操作流速、果汁中果酸浓度以及温度对LSI-1031阴离子交换树脂动态动力学曲线都有影响,柱处理最佳条件为:流速3BV/h、温度50℃,并且低果酸浓度的果汁有利于提高树脂的处理量。     

V_E纳米脂质载体的制备与性质研究

以硬脂酸、单硬脂酸油脂、三丁酸甘油酯为原料,采用乙醇注入超声法制备了VE纳米脂质载体,并对其形态、粒径、表面电位、包封率进行考察。结果表明所制备的纳米脂质载体平均粒径为180.3nm,多分散指数PDI为0.205,表面Zeta电位为（-31.4±4.1）mV,平均包封率为77.2%。     

The influence of carbon dioxide on gas exchange of mungbean sprouts at aerobic and anaerobic conditions

Gas-exchange models are often used to predict gas conditions inside modified atmosphere (MA) packages of fresh plant products. Current models describing CO₂ production of harvested plant products do not account for an inhibition of a high partial pressure of CO₂ on fermentation rates, whereas such as inhibition on plant metabolism is often found. An existing gas-exchange model was modified to include this inhibition. Gas-exchange data of mungbean sprouts were collected under various partial pressures of O₂ and CO₂ and used to validate the model. With the modification applied, CO₂ production rates were better described. Although CO₂ production at low O₂ was reduced by high partial pressures of CO₂, no influence was found on ethanol and acetaldehyde levels. The data found also indicate large differences between gas-exchange rates of different batches of mungbean sprouts. It is suggested that microbial metabolism attributes substantially to total CO₂ production rates found and that it might explain these differences. © 1998 SCI.     

Fortification of set yogurt with passion fruit juice: Effects on fermentation kinetics,physicochemical properties,and functionality

With the purpose of developing an alternative set yogurt with high consumer acceptability, passion fruit juice, at levels that varied from 0 to 10%, was incorporated into set yogurt, and the effects on the fermentation kinetics, physicochemical properties, and functionality of set yogurt were evaluated. The results showed that the addition of passion fruit juice was simultaneously propitious for milk acidification in earlier fermentation stages and reduced the fermentation rate at later stages of fermentation. The phenolic compounds and pectin in passion fruit juice interacted with caseins to form soluble complexes, enhancing the gel strength of set yogurts by 7.5%. The aroma and flavor of the set yogurt was improved as well. However, with the addition of 10% passion fruit juice, the gel structure was destroyed, and the quality of the set yogurt was very degraded. More importantly, the addition of passion fruit juice increased the polyphenol content and significantly enhanced the antioxidant activity of the set yogurt. This investigation demonstrated the feasibility of fabricating passion fruit juice-enriched set yogurt and its superior quality compared with the corresponding normal product.     

Effect of enzymatic debittering on antioxidant capacity and protective role against oxidative stress of grapefruit juice in comparison with adsorption on exchange resin

Antioxidant capacity, radical scavenging activity, as well as protective effect on lipoperoxidation, glutathione oxidation and DNA damage, were evaluated in grapefruit juice subjected to bitterness removal by naringinase or by physical adsorption with Amberlite®IRA-400. The results showed a reduction in naringin content for the naringinase-treated juice (N-PJ) and those processed with the exchange resin (R-PJ), which made both juices acceptable to consumers. Total antioxidant capacity, measured by ABTS and FRAP assays, was lower in R-PJ samples. The highest superoxide and hydroxyl radical scavenger activity was observed in N-PJ. With regard to inhibitory effect of juice samples on lipoperoxidation, N-PJ also provided the greatest effectiveness. In addition, R-PJ showed the lowest levels of GSH. The results showed a protective effect on DNA oxidative damage for all juice samples tested. In summary, enzymatic technology was more effective than physical adsorption in preserving the antioxidant and biomolecule protection capacity of fresh grapefruit juice.     

石蒜(Lycoris radiate.Herb)鳞茎浆料流体特性及其用于酒精发酵的研究

通过分析石蒜鳞茎制浆所得浆料的静态及动态流体学特性,讨论该浆料用于酒精发酵的可行性。结果表明,鳞茎浆料具备典型粘弹性流体性质以及其粘性起主导作用。分别利用葡聚糖酶、木聚糖酶及果胶酶与浆料反应以降低其粘性,均表现出有效降粘效果。并探讨了这三种不同酶预处理分别对同步糖化发酵工艺利用浆料发酵酒精过程的影响,结果显示,浆料经果胶酶预处理后,酿酒酵母培养70h产酒精1.9%(w/w)为最高。浆料中石蒜生物碱可能对酵母某些代谢途径产生抑制。文章最后提出对石蒜属植物的综合生物炼制策略,以期实现对本属植物的高效开发。     

Effect of lactose hydrolysis on the milk-fermenting properties of Lactobacillus delbrueckii ssp. bulgaricus 2038 and Streptococcus thermophilus 1131

Yogurt is a well-known nutritious and probiotic food and is traditionally fermented from milk using the symbiotic starter culture of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. However, yogurt consumption may cause health problems in lactose-intolerant individuals, and the demand for lactose-free yogurt has been increasing. The standard method to prepare lactose-free yogurt is to hydrolyze milk by lactase; however, this process has been reported to influence the fermentation properties of starter strains. This study aimed to investigate the fermentation properties of an industrial starter culture of L. bulgaricus 2038 and S. thermophilus 1131 in lactose-hydrolyzed milk and to examine the metabolic changes induced by glucose utilization. We found that the cell number of L. bulgaricus 2038, exopolysaccharide concentration, and viscosity in the coculture of L. bulgaricus 2038 and S. thermophilus 1131 was significantly increased in lactose-hydrolyzed milk compared with that in unhydrolyzed milk. Although the cell number of S. thermophilus 1131 showed no difference, production of formic acid and reduction of dissolved oxygen were enhanced in lactose-hydrolyzed milk. Further, in lactose-hydrolyzed milk, S. thermophilus 1131 was found to have increased the expression of NADH oxidase, which is responsible for oxygen reduction. These results indicated that glucose utilization promoted S. thermophilus 1131 to rapidly reduce the dissolved oxygen amount and produce a high concentration of formic acid, presumably resulting in the increased cell number of L. bulgaricus 2038 in the coculture. Our study provides basic information on the metabolic changes in starter strains in lactose-hydrolyzed milk, and demonstrates that lactose-free yogurt with increased cell number of L. bulgaricus can be prepared without delay in fermentation and decrease in the cell number of S. thermophilus.     

菌株性能及球杆菌比例对酸奶品质的影响

分析测定了从某直投式发酵剂中分离的两株嗜热链球菌（Streptococcus thermophilus）S.t S1、S.t R1和一株保加利亚乳杆菌（Lactobacillus delbrueckii subsp.bulgaricus）L.bL1的发酵性能,并将球菌与杆菌以不同比例组合发酵,比较酸奶发酵时间、粘度、乳清析出、后酸化和感官评价差异。结果表明,嗜热链球菌S.tS1生长速度略慢于S.tR1,酸化速度相当,但S.tS1的胞外多糖产量和发酵乳粘度明显高于S.tR1,保加利亚乳杆菌L.bL1的上述性能均比两株球菌差。S.tS1与L.bL1菌株以100：1的比例进行组合发酵时,粘度达0.549Pa·s;乳清析出仅2.5mL/10g;4℃冷藏保存15d后,酸度上升12°T,酸奶产品各项指标优于其他菌株组合。菌株性能和组合方式对酸奶产品的品质具有显著的影响。     

Varying protein and starch in the diet of dairy cows. I. Effects on ruminal fermentation and intestinal supply of nutrients

The main objective of this experiment was to examine the effects of the percentage and source of crude protein (CP) and the amount of starch in the diet of dairy cows on ruminal fermentation, nutrient passage to the small intestine, and nutrient digestibility. For this purpose, 6 multiparous Holstein cows fistulated in the rumen and duodenum that averaged 73 d in milk were used in a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of treatments. Two sources of CP [solvent-extracted soybean meal (SBM) and a mixture of SBM and a blend of animal-marine protein supplements plus ruminally protected Met (AMB)] and 3 levels of dietary protein (about 14, 16, and 18%) were combined into 6 treatments. On a dry matter (DM) basis, diets contained 25% corn silage, 20% alfalfa silage, 10% cottonseed, 26.7 to 37% corn grain, and 4 to 13.5% protein supplement. Intakes and digestibilities in the rumen and total tract of DM, organic matter, acid and neutral detergent fiber were unaffected by treatments. Increasing dietary CP from 14 to 18% decreased the intake and apparent ruminal and total tract digestion of starch, but increased the proportion of starch consumed by the cows that was apparently digested in the small intestine. At 14% CP, starch intake and total tract digestion were higher for the AMB diet than for the SBM diet, but the opposite occurred at 16% CP. Across CP sources, increasing CP in the diet from 14 to 18% increased the intakes of N and amino acids (AA), and ruminal outflows of nonammonia N, nonammonia nonmicrobial N, each individual AA except Met, total essential AA, and total AA. Across CP percentages, replacing a portion of SBM with AMB increased the intake of Met and Val and decreased the concentration of ammonia N in the rumen, but did not affect the intake of other essential AA or the intestinal supply of any essential AA and starch. The ruminal outflow of microbial N, the proportional contribution of Lys and Met to total AA delivered to the duodenum, and milk yield were unaffected by treatments. Data suggest that the intake of N by high-producing dairy cows that consume sufficient energy and other nutrients to meet their requirements can be decreased to about 600 to 650 g daily without compromising the supply of metabolizable protein if the source and amount of dietary CP and carbohydrate are properly matched.