维生素C二步发酵菌发酵条件的优化

目的:改变发酵条件以提高发酵收率.方法:优化pH值、通风量、微量元素等发酵因子,找到最佳使用量.结果:发酵培养基中L-山梨糖起始浓度8%、碳酸钙浓度0.05%、复合VB以及分段调节pH值、通气量等可以有效地提高2-酮基-L-古龙酸的产量.结论:通过优化发酵条件可以优化发酵菌系的生理状态,促进大小菌之间的协调,使其达到最佳发酵状态.     

红茶发酵影响因素及品质调控技术研究进展

红茶是我国主要的消费茶类之一,其加工步骤为萎凋、揉捻、发酵和干燥,其中发酵是红茶品质特征形成的关键环节。关于红茶发酵过程中影响因素及品质调控技术,已有文献表明,多酚类物质含量及组成比例、酶种类及其活性、温度、湿度、pH,以及发酵过程中微生物等内部及环境因素均会影响红茶品质特征化合物的形成,从而影响其品质。目前常用的品质调控技术主要包括新发酵技术、冷冻萎凋技术、外源酶技术以及光质。未来研究重点将是优化红茶适制品种培育、环境因子间的交互作用机制、微生物对红茶发酵品质的影响机制和加工设备智能化等方面,因此本文通过对红茶发酵影响因素及品质调控技术的研究进展进行综述,以期为提升红茶的滋味品质和推进红茶新研究进展提供借鉴与参考。     

L-乳酸高产突变株--米根霉NAF-032

运用正交试验理论,对L-乳酸高产突变株NAF-032的优化摇瓶发酵条件作了初步研究,确定了优化的发酵培养基和发酵条件.优化发酵培养基为(g/L)葡萄糖140,氯化铵1,KH2PO40.3,MgSO4*7H2O0.25,ZnSO4*7H2O0.08;优化培养条件为34℃,摇床转速200r/min,装液量50mL(250mL容积三角瓶),一次性添加CaCO380g/L调节pH值.米根霉NAF-032的摇瓶发酵L-乳酸积累量可达94.28g/L.     

微生物发酵草莓,海带汁的研究

研究了优良发酵菌株的配比，用盐酸和柠檬酸等对海带脱腥，草莓汁制取时的较适比例，它们发酵时的产气量，发酵条件的影响，以及对工艺条件进行了探讨。     

液态深层发酵水果醋的工艺优化

对水果醋液态发酵工艺进行优化.研究了扩培式、直投式发酵对醋酸发酵的影响;不同碳源氮源对醋酸发酵的影响,以及碳氮比的关系;对温度、接种量,通气量、酒精度等因素进行了正交试验,分析了各因素对醋酸发酵的影响效果,确定了最佳组合;最后通过果醋发酵试验,验证了醋酸发酵优化工艺能够提升产品品质,降低生产成本,并可以成功的用于实际生产.     

短乳杆菌发酵苹果汁工艺优化及有机酸变化

该研究利用短乳杆菌发酵苹果汁,生产能够调节人体肠道功能的乳酸菌苹果汁。通过单因素实验确定最适碳源、氮源以及缓冲因子;并以总酸、还原糖的变化为依据,进行响应面优化,确定最适发酵工艺条件,采用高效液相色谱法测定苹果汁发酵过程中有机酸组成及含量变化。结果表明,优化后发酵苹果汁的最佳培养基条件为:葡萄糖质量浓度50 g/L,蛋白胨质量浓度9 g/L,K_2HPO_4质量浓度4 g/L;菌种接种量为8%,发酵温度为36℃,发酵时间为6 d。在该条件下测得苹果汁的总酸为2. 61 g/100 g、还原糖为5. 027 g/100 g;经短乳杆菌发酵后苹果汁的品质明显优于发酵前。发酵后乳酸、富马酸、乙酸、奎宁酸含量显著增多;苹果酸、琥珀酸含量均持续减少,酒石酸含量无明显变化。     

DPS数据处理软件在发酵培养基优化中的应用

在发酵工业中,发酵培养基的优化对发酵水平的提高具有非常重要的作用.DPS(Data ProcessiIlgSystem)是一款强有力的数据处理软件,兼具多种类型的试验设计技术以及齐全的统计分析功能.文中介绍了DPS数据处理软件在发酵培养基优化中的具体实施方法和步骤,运用该软件对试验结果进行处理,结果表明,DPS数据处理软件能简单且有效地对发酵培养基进行优化.     

柠檬酸发酵现状及展望

柠檬酸是微生物发酵法生产的重要有机酸之一,用途极为广泛.文章论述了黑曲霉发酵柠檬酸的发酵机制及代谢调控,介绍了柠檬酸发酵的菌种,原料以及发酵过程的影响因子.最后对柠檬酸发酵中的存在的问题提出建议.     

桂花红枣果醋的醋酸发酵工艺研究

以桂花、红枣为原料,通过单因素及正交试验,研究了桂花红枣果醋的醋酸发酵工艺条件。对发酵桂花红枣酒醪预处理、碳源、无机盐、发酵温度、初始酒精度、接种量、初始pH、转速、装液量等条件进行了优化,桂花红枣酒醪液不灭菌,初始酒精度调节为5%(V/V),加1%葡萄糖、0.05%磷酸二氢钾以及0.05%硫酸镁,调节初始pH值至5.0,接种量8%,发酵温度30℃,转速160r/min,装液量40%,发酵时间5天,得到的桂花红枣果醋颜色红亮,花香、枣香、醋香协调,怡悦适口,风格独特。     

果胶酶产生菌的选育

本试验筛选到一株适于使苹果汁澄清的果胶酶产生黑曲菌No.07,应用物理因素及化学因素对No.07进行处理,从白色突变菌落中获得一高产株CL—8501,对CL—8501的培养基及发酵条件进行了优化,在优化的培养基及较适条件下,CL—8501产酶达631.6单位/毫升,产量此出发株No.07提高约105倍。     

Anti-obesity effects of conjugated linoleic acid, docosahexaenoic acid, and eicosapentaenoic acid

Obesity has become a prevailing epidemic throughout the globe. Effective therapies for obesity become attracting. Food components with beneficial effects on "weight loss" have caught increasing attentions. Conjugated linoleic acid (CLA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) belong to different families of polyunsaturated fatty acids (PUFA). However, they have similar effects on alleviating obesity and/or preventing from obesity. They influence the balance between energy intake and expenditure; and reduce body weight and/or fat deposition in animal models, but show little effect in healthy human subjects. They inhibit key enzymes responsible for lipid synthesis, such as fatty acid synthase and stearoyl-CoA desaturase-1, enhance lipid oxidation and thermogenesis, and prevent free fatty acids from entering adipocytes for lipogenesis. PUFA also exert suppressive effects on several key factors involved in adipocyte differentiation and fat storage. Despite their similar effects and shared mechanisms, they display differences in the regulation of lipid metabolism. Moreover, DHA and EPA exhibit "anti-obesity" effect as well as improving insulin sensitivity, while CLA induces insulin resistance and fatty liver in most cases. A deeper and more detailed investigation into the complex network of anti-obesity regulatory pathways by different PUFA will improve our understanding of the mechanisms of body weight control and reduce the prevalence of obesity.     

膜分离技术在氨基酸发酵生产中的应用

文章简要介绍了膜的种类、作用机理,并从氨基酸发酵液菌丝体的去除、等电点回收氨基酸及废水处理等方面阐述了膜分离技术在氨基酸生产行业中的应用,膜分离技术的应用为氨基酸行业实施高效、清洁生产提供了坚实的技术保障.     

酸性蛋白酶在镇江香醋生产中的应用研究

本实验研究了酸性蛋白酶的添加方式和添加量对醋醅酸度和氨基酸态氮含量的影响。结果表明:在醋酸发酵阶段添加15 U/g糯米的酸性蛋白酶,醋醅酸度提高了1.33%,氨基酸态氮含量提高了40%。该方法方便实用,为镇江香醋的生产提供了一种优化方法。     

青梅酒的总酸和挥发酸控制技术研究

该试验以青梅酒为研究对象,以总酸和挥发酸含量为主要评价指标,确定最佳控酸技术并优化其控酸工艺条件。通过比较碳 酸钙法、碳酸氢钾法、碳酸钾法和树脂D630法4种控酸技术对降低青梅酒中总酸和挥发酸含量以及感官品评的影响,确定最佳控酸 技术为树脂D630法。 通过单因素和正交试验确定了树脂D630法的最佳控酸工艺条件为树脂D630添加量3%,作用时间90 min,搅拌 速率150 r/min。 在此最优条件下,青梅酒中的总酸和挥发酸含量分别为4.06 g/L、0.98 g/L,较优化前分别降低了15.06%、4.85%,酒精 度为17.9%vol,总糖含量为28.5 g/L,感官评分为92分。     

乳酸菌环境胁迫应激的分子调控机制研究进展

对乳酸菌在环境胁迫下的应激反应及其分子机制进行了综述,并着重从细胞和分子水平,探讨了乳酸菌在温度、pH值、氧、渗透压、高压和饥饿等胁迫条件下,应激蛋白和代谢产物的诱导合成以及基因调控机制。深入了解乳酸菌应激反应的分子机制、以及基因和蛋白质组水平的适应性变化,可以为改进乳酸菌发酵条件和菌种改良提供有价值的理论依据。     

Response of a Lactobacillus plantarum human isolate to tannic acid challenge assessed by proteomic analyses

Scope : To gain insight on the mechanisms used by intestinal bacteria to adapt and resist the antimicrobial action of dietary tannins and identify targets for tannic acid in Lactobacillus plantarum. Methods and results : A proteomic analysis of an L. plantarum human isolate exposed to the tannic acid challenge was undertaken. Tannic acid targeted proteins involved in outstanding processes for bacterial stress resistance including cyclopropanation of membrane lipids, stress response at population scale and maintenance of cell shape. To respond to this aggression, tannic acid‐misfit cells of L. plantarum challenged with tannic acid reorganized their metabolic capacity to economize energy and express proteins involved in oxidative stress defense and cell wall biogenesis, indicating that the injury incurred by tannic acid was based on oxidative damage and disruption of the cell envelope. The induction of 3‐octaprenyl‐4‐hydroxybenzoate carboxy‐lyase, which is sensitive to changes in redox conditions and involved in ubiquinone biosynthesis in other bacteria, suggests for a tannic acid‐induced redox imbalance. Conclusion : The results reveal the adaptation of a gastrointestinal isolate of L. plantarum to tannic acid and identify antibacterial targets for this dietary compound. This provides the basis for the selection of tannin‐resistant microorganisms and their use to obtain health benefits from tannin‐containing diets.     

Lactic-acid stress causes vacuolar fragmentation and impairs intracellular amino-acid homeostasis in Saccharomyces cerevisiae

To gain more insight into adaptation response to lactic-acid stress in yeast, a genome-wide screening for genes whose disruption caused hypersensitivity to 4.0% l-lactic acid (pH 2.8) was performed using the gene deletion collection of Saccharomyces cerevisiae. We identified 107 genes that contributed significantly to the ability of yeast cells to adapt lactic-acid stress. More than 30% of the genes identified in this screening were newly identified to be involved in mechanisms for adaptation response to lactic acid. We found that protein urmylation by Uba4 and N-terminal acetylation by Nat3 were involved in lactic acid adaptation mechanisms. Functional categorization of the genes followed by microscopic analysis revealed that a variety of cellular functions were involved in adaptation response to lactic acid and function associated with vacuolar transport played important roles in adaptation response to lactic acid. We also found that vacuole fragmented immediately upon exposure to lactic- and hydrochloric-acid stress. In addition, our analysis revealed that lactic-acid stress significantly reduced the amount of intracellular amino acids. Amino acid supplementation recovered the adaptation deficiency to lactic acid, suggesting that intracellular amino-acid homeostasis plays important roles in adaptation response to lactic-acid stress. These data suggest that enhancing vacuolar integrity, as well as maintaining intracellular amino-acid homeostasis may be an efficient approach to confer resistance to lactic-acid stress.     

传统发酵蔬菜中耐乙醇型乳酸菌的研究进展

发酵蔬菜一般都是由乳酸菌等多种微生物发酵而成,发酵过程中会产生有机酸、乙醇、氨基酸等物质。乙醇和有机酸形成酯类物质,赋予发酵蔬菜特有的香气。但是发酵蔬菜发酵过程中如果乙醇浓度过高,则会抑制乳酸菌发挥作用。因此,该文主要总结传统发酵蔬菜中乳酸菌的筛选方法、乳酸菌培养基优化、乳酸菌的乙醇耐受性、乳酸菌的诱变、乳酸菌的复配及应用等方面的研究进展,为人工接种乳酸菌发酵传统蔬菜产业化生产提供依据。     

GC-MS联用测定酸乳饮料中山梨酸含量

介绍了气相色谱、质谱联用测定酸乳饮料中山梨酸含量的方法。此方法定性、定量分析准确、简便,可为食品中防腐剂的分析检测提供参考。     

乳酸菌群体感应的研究进展

乳酸菌的益生特性已引起公众的广泛关注。群体感应是细菌感受外界环境变化并做出反应的转导机制,对乳酸菌的存活及益生特性至关重要。因此,近些年来乳酸菌的群体感应成为研究热点。该文综述了乳酸菌群体感应的信号分子及其双组分系统,群体感应对乳酸菌环境适应的调控（生物膜、耐酸、耐胆盐）,群体感应对乳酸菌益生特性（抑制致病菌、与宿主相互作用）的影响以及实际应用,为乳酸菌群体感应今后的基础研究和工业化应用提供参考。