胞内海藻糖含量对冷冻面团中酵母抗冻性的影响

用不同的方法将活性干酵母进行了处理，研究了处理后的酵母在冷冻面团体系中的发酵力和抗冻力，试验发现，用高渗溶液、甘油和海藻糖的处理的酵母发酵力均有所提高，其中海藻糖处理对酵母的抗冻力的保护作用非常显著，冷冻一个月后酵母抗冻力可达到80．7％。为了分析抗冻性的提高是否与酵母胞内海藻糖含量有关，分剐测试了几种不同方法处理的酵母的胞内海藻糖含量，发现在酵母海藻糖含量大于12％时，抗冻性与海藻糖含量没有直接相关性。复合处理的酵母发酵力提高，但不适于冷冻，推测是由于细胞膜稳定性下降。     

酵母精

鲜面包酵母经破壁处理后,进行自溶,再添加磷酸二酯酶以降解酵母核糖核酸,可获得营养丰富、香气浓郁、滋味鲜美的酵母抽提物。本文研究了酵母自溶的最佳条件,优选了两种方法,结果如下:1.外加化学物质。添加54％氯化钠(以酵母干重计)和54％乙醇(以酵母悬浮液体积计),pH6.0,温度50℃;2.外加蛋白酶。添加量0.6％(以酵母干重计),pH6.5,温度58℃。比较了麦芽根及桔青霉的磷酸二酯酶降解酵母核糖核酸的效果,认为采用麦芽根能以低成本获取安全可靠、酶活力较高的酶液。     

啤酒废酵母自溶制备氨基酸液的研究

本文对啤酒废酵母自溶条件进行了研究,得出自溶最优条件为：助溶剂NaCl2％、自溶温度50℃、自溶时间24小时、pH4．5～7。酵母自溶液对酵母的生长有促进作用。     

杨桃干型果酒固定化发酵研究

研究几种酵母固定化发酵杨桃果汁制作干型杨桃果酒的发酵工艺。杨桃进行酶解取汁、成分调整后。分别进行固定化和游离发酵对比试验、不同温度下固定化发酵对比试验、复合酵母茵种固定化发酵优化试验。结果表明,杨桃果汁加入200mg,L偏重亚硫酸钾,调整总糖261g／L,总酸（以柠檬酸计）5．5g／L,并以0．2％葡萄酒干酵母为主发酵菌种,配合0．05％生香干酵母和0．05％酿酒高活性干酵母进行固定化发酵,可得到酒质较好的干型杨桃果酒。     

酵母抽提物自溶工艺优化

以高活性面包酵母为原材料,通过酵母自溶获得酵母抽提物,研究影响自溶过程中的各种因素,通过单因素及正交试验,优化得到最佳的环境条件为:温度45℃,pH6.5,料液比1∶10,添加2%NaCl和0.5%乙醇,获得酵母抽提物氨基酸态氮的含量为4.16%;再经高压均质的破壁处理,结合对自溶过程进行摇床振荡,酵母抽提物的氨基酸态氮得率较未经处理的提高了29%,达到5.45%,获得的酵母提取物风味醇厚,呈鲜味,略带酱香气。     

啤酒废酵母自溶条件的研究

本文探讨了以啤酒废酵母为原料，采用自溶法生产酵母抽提物的条件。结果表明：以食盐为啤酒酵母自溶促进荆的最佳作用条件是10％的啤酒酵母悬浮液在pH5．0、温度50℃、食盐浓度3％T，自溶40h，所得酵母抽提液的氨基氮含量为O．498g／100mL．产品得率47．50％。风味非常醇厚。     

利用啤酒酵母生产酵母味素的研究

以啤酒酵母为主要原料，通过自溶法和酶解法生产酵母味素。研究了洗涤、均质、自溶时间、酶制剂的选择及搅拌等因素对酵母细胞自溶的影响。得出了啤酒酵母自溶的最佳工艺条件，即啤酒酵母经0．5％NaHCO3脱苦，加2．5倍体积的水和3％食盐，胶体磨均质1min，55℃自溶10h，加入1．5％蛋白酶和0．2％葡萄糖酶自溶12h（搅拌20min停30min），然后95℃灭酶10min，再加入核酸酶55℃自溶3．5h，经分离、浓缩可获得68．5％N酵母味素。     

提取啤酒废酵母中葡聚糖及回收蛋白质工艺探讨

以啤酒废酵母为原料，采用较为简单、环保的酶促-自溶-碱法提取葡聚糖并回收蛋白质，结果表明，采用此法获得的葡聚糖得率和纯度分别为45．8％和33．6％；利用回收的蛋白质制备蛋白质饲料，得率达到91．49％。经成本核算，以年产10t葡聚糖计，每年可实现利润282．55万元，具有很好的发展前景。     

草莓果酒的酵母发酵特性研究

以草莓鲜果为原料，接种酿酒活性干酵母，添加复合酶制剂、白砂糖。在常温（17．5-22．5℃）下进行全果发酵。结果表明，摘除萼片和枝梗的草莓鲜果经0．5％。高锰酸钾溶液浸泡20s，清水冲洗，复合酶制剂下胶处理15h后进行发酵，发酵所得草莓酒的各项指标均达到优质果酒标准。试验用活性干酵母对草莓果浆发酵速率快，发酵能力强。     

提高酵母精呈味核苷酸含量的研究

本文试验以啤酒废酵母为原料，采用自溶液中外加从大麦芽根中提取的5‘-磷酸二脂酶，来探讨啤酒废酵母自溶过程中不同因素对5‘-磷酸二脂酶定向水解酵母RNA生成5‘-核苷酸的影响，然后得出提高酵母精中呈味核苷酸含量的最佳酶解工艺条件，从而大大地提高了酵母精中呈味核苷酸的含量，生产的膏状酵母精（含水份28．7％）产品中5‘-核苷酸含量高达2067.5mg/100g。     

西番莲干型果酒固定化发酵工艺

探讨了几种酵母固定化发酵含酸量较高的西番莲果汁制作干型西番莲果酒的发酵工艺。对西番莲进行酶解取汁、成分调整后,分别进行了固定化发酵和游离发酵对比试验,不同温度下固定化发酵对比试验以及采用复合酵母菌种固定化发酵方式进行酒质优化试验。结果表明:西番莲果汁加入0.02%偏重亚硫酸钾,调整pH3.8,总糖20.8%,总酸(以柠檬酸计)1.2%,并以0.3%葡萄酒干酵母为主发酵菌种,配合0.05%生香干酵母和0.05%酿酒高活性干酵母进行固定化发酵可得到酒质较好的中等酒精度(11%v/v￣13%v/v)的干型西番莲果酒。     

不同还原糖对鲢鱼肉糜凝胶品质的影响

鲢鱼蛋白质凝胶性差、鱼腥味重是限制其精深加工的主要原因。为了探究糖基化对鲢鱼肉糜凝胶色泽、质构及风味等的影响,选取葡萄糖、低聚异麦芽糖、葡聚糖、L-阿拉伯糖和木糖作为还原糖。利用紫外分光光度计、色差仪、pH计、质构仪和感官评价测定样品的接枝度、色泽、pH值、质构和风味变化。结果表明:添加L-阿拉伯糖和木糖的鲢鱼肉糜凝胶的接枝度高达(58.24±0.62)%和(61.89±2.06)%,与未加糖的对照组相比,2组样品的pH值显著下降(P<0.05),褐变和质构指标显著增加(P<0.05);定量描述分析发现,糖基化可以降低鲢鱼肉糜凝胶的鱼腥味,增加肉香味、烤味和烧焦味;喜好度评价表明,要控制接枝度为44.85%～61.89%,才能获得整体可接受度良好的产品。因此,L-阿拉伯糖和木糖是2种较好的还原羰基,可以用于增强鲢鱼肉糜凝胶的质构和香气。     

一种天然“藻茶”的研制

以螺旋藻粉(Spirulina platensis)为原料,采用超声方法进行破壁,在温度为45℃,物料比为1g/100mL,时间20 min条件下破壁效果较好.同时研究活性酵母发酵除腥工艺,添加葡萄糖0.4％,酵母0.10％,控制温度为35℃,发酵60 min除腥效果最优.离心分离得到藻清液,适当添加甜味剂、增香剂和稳定剂,加热杀菌处理,制成了色泽和风味独特的天然螺旋藻营养饮料“藻茶”.     

Sporidiobolus pararoseus WZ012产类胡萝卜素发酵条件的优化

以响应面方法对Sporidiobolus pararoseus WZ012产类胡萝卜素的摇瓶发酵条件进行了优化。在Plackett-Burman实验的基础上,利用中心组合设计研究了4个主要因素(葡萄糖、酵母膏、KH2PO4、接种量)对产类胡萝卜素的影响。结果表明,较高浓度的酵母膏和较大的接种量有助于类胡萝卜素的生产,而较高浓度的葡萄糖和KH2PO4有助于生物量的提高,生物量与类胡萝卜素产量之间没有必然的联系。优化得到的发酵培养基组成(g/L)为:葡萄糖60.23、酵母膏12.21、KH2PO41.68、接种量为8.38%。在此条件下红酵母产类胡萝卜素的最大产量为29.3mg/L,较优化前提高了54.1%。类胡萝卜素成分分析表明主要含有β-胡萝卜素、圆酵母素和红酵母红素这3种类胡萝卜素物质,其中β-胡萝卜素占62.5%。     

耐高渗酵母产赤藓糖醇的影响因素

球拟酵母OS-194是一株单产赤藓糖醇的耐高渗酵母,该菌株高产赤藓糖醇的最佳培养基配方为葡萄糖10g/dL,酵母膏0.5g/dL,尿素0.1g/dL.最适培养条件是在摇瓶转速150r/min的条件下于35℃培养4d.在上述培养条件下,该菌株赤藓糖醇的耗糖转化率高达29.6%.磷是限制OS-194菌株高产赤藓糖醇的主要因素,当培养液中的磷质量浓度低于31.5mg/L时,赤藓糖醇的产量最高;随着磷质量浓度的升高,该菌株赤藓糖醇的产量降低,而酒精的产量和生物量却有明显升高.同时,OS-194菌株还能利用果糖、蔗糖和D-甘露糖产赤藓糖醇.     

Catalytic activity of yeast extract in biofuel cell

It was revealed that the dry powder yeast extract (YE) has the ability to act as a biocatalyst as well as a mediator in a biofuel cell. The yeast extract, from Nihon Pharmaceutical Co., Ltd., was used as a biocatalyst in an open air cathode biofuel cell containing phosphate buffer for glucose oxidation. The anode medium with only the YE showed an immediate activity by producing a current and delivering power depending on its concentration. By adding glucose to the anode medium, the anode potential decreased with time to -0.2?V vs. normal hydrogen electrode (NHE), and produced a higher power compared to that without glucose. The biofuel cell produced an open circuit voltage (OCV) as high as 1?V.     

芒果胡萝卜复合果酒发酵工艺的研究

以芒果和胡萝卜为原料酿造复合果酒,并对其发酵工艺进行研究。采用单因素实验和响应面优化试验,分析原料比、SO₂添加量、初始糖度、初始pH、酵母添加量对复合果酒发酵的影响,并得到最优发酵条件。结果表明,最佳发酵条件为:芒果与胡萝卜原料比例为2:1(V/V)、SO₂添加量为55 mg/L、初始糖度为24%、初始pH为3.5、酵母接种量为0.12%。在此最优条件下,芒果胡萝卜复合果酒酒精度为13.62% vol、残糖4.6 g/L、总酸8.8 g/L、干浸出物23.0 g/L、甲醇98 mg/L。酒体色泽橙黄饱满、透明清亮,有浓郁的果香和酒香,口感甘甜醇厚。     

均匀设计法优化廉价型牛凝乳酶工程菌发酵培养基

为了获得生产用廉价型牛凝乳酶工程菌发酵培养基,通过单因素试验考察发酵培养基中各组分对产酶的影响。结果显示：葡萄糖、玉米浆、酵母提取物、尿素质量浓度对产酶影响显著。以上述因素作为随机因子,进行均匀设计试验,采用逐步回归方法对试验结果进行分析。结果表明：在葡萄糖45g/L、玉米浆17g/L、酵母提取物6g/L、尿素12g/L的条件下,凝乳酶活性达342.86SU/mL,比优化前提高了1.22倍。所得培养基为重组牛凝乳酶的高效低成本生产提供了参考。     

Inhibitory effect of mineral ion accumulation on high density growth of the hyperthermophilic archaeon Sulfolobus solfataricus

A fed-batch operation for high density cultivation of Sulfolobus solfataricus (DSM 1617) in a bench-top fermentor using a feed medium composed of glucose and yeast extract was investigated. The highest maximal cell density obtained in controlled fed-batch cultures was 21.7 g/l. Although higher yeast extract concentrations in the medium favored greater cell biomass yield, cell growth ceased with low cell densities. It was observed that large amounts of inorganic ions, such as sulfate, ammonium, potassium and phosphate ions, were accumulated in the culture broth at higher yeast extract concentrations. This was due to either the addition of the titrant or feeding of yeast extract during cultivation. Fed-batch cultures with additional mineral salts in the feed medium showed much lower cell biomass, indicating that accumulation of inorganic ions has a significant inhibitory effect on the growth of S. solfataricus. Inhibition of cell growth by the presence of mineral ions was further confirmed by the batch culture experiments. Some plausible mechanisms which can account for the growth inhibition at higher mineral ion concentrations have been suggested.     

Effect of trisodium phosphate solutions washing on the sensory evaluation of poultry meat

The effect of trisodium phosphate (TSP) solutions treatments on the sensory evaluation of poultry meat has been explored since TSP was recently approved by USDA for its usage in poultry processing to eliminate Salmonella contamination. In the present study, fresh chicken thighs were dipped in water (control sample) and in 8, 10 and 12% TSP solutions (treated samples) for 15 min. Raw samples' color, smell and overall acceptability and cooked thighs' color, smell, flavor, texture and overall acceptability were evaluated by consumer panelists. The evaluation of raw pieces after treatment or after 7 days storage at 2°C revealed that, with the exception of 12% TSP solutions treatment, sensory quality was not adversely affected by TSP. The color, smell and overall acceptability hedonic scores for the boiled thigh meat were not different between the treated samples and the control ones. Only the color, flavor and overall acceptability of thighs dipped in 12% TSP were rated significantly lower than the control sample. These results suggested that TSP solutions have good potential as dips to sanitize chickens carcasses