Isolation of tocopherol and sterol concentrate from sunflower oil deodorizer distillate

The isolation of tocopherols and sterols together as a concentrate from sunflower oil deodorizer distillate was investigated. The sunflower oil deodorizer distillate was composed of 24.9% unsaponifiable matter with 4.8% tocopherols and 9.7% sterols, 28.8% free fatty acid (FFA) and 46.3% neutral glycerides. The isolation technology included process steps such as biohydrolysis, bioesterification and fractional distillation. The neutral glycerides of the deodorizer distillates were hydrolyzed byCandida cylindracea lipase. The total fatty acids (initial FFA plus FFA from neutral glycerides) were converted into butyl esters withMucor miehei lipase. The esterified product was then fractionally distilled in a Claisen-vigreux flask. The first fraction, which was collected at 180–230°C at 1.00 mm of Hg for 45 min, contained mainly butyl esters, hydrocarbons, oxidized products and some amount of free fatty acids. The fraction collected at 230–260°C at 1.00 mm Hg for 15 min was rich in tocopherols (about 30%) and sterols (about 36%). The overall recovery of tocopherols and sterols after hydrolysis, esterification and distillation were around 70% and 42%, respectively, of the original content in sunflower oil deodorizer distillate.     

毛霉蛋白酶在腐乳成熟中的作用

采用SDS—PAGE与ESI—MS相结合的方法研究了毛霉蛋白酶和Alcalase蛋白酶对SPI的酶促降解作用，研究结果表明，Alcalase是一种典型的内切型蛋白酶，它能在1h内催化大豆蛋白降解为分子量10000D以下的肽段，但降解产物容易相互聚合而沉淀，毛霉蛋白酶则具有较强的肽酶活性，能够以大豆蛋白或多肽为底物酶促降解生成多量的水溶性肽，为后期嗜盐菌的生长提供了可供利用的速效氮素营养，毛霉蛋白酶还具有消除苦味、形成鲜味物质的作用，与腐乳风味形成有关。     

Medium Optimization of Gamma Linolenic Acid Production in Mucor rouxii CFR -G15 using RSM

Omega-6 polyunsaturated fatty acids has both pharmaceutical and neutraceutical importance. Central composite rotatable design (CCRD), along with response surface methodology (RSM), was employed to optimize the medium components for maximum production of gamma linolenic acid (GLA) from Mucor rouxii CFR-G15. Nutritional parameter such as carbon (glucose) and nitrogen (yeast extract and ammonium nitrate) sources were focused in this study to enhance the GLA production. The optimal conditions for maximizing GLA production (18.55%) were at 65 g glucose per liter; 3.5 g yeast extract per liter, and 0.5 g ammonium nitrate per liter. Thus, by using CCRD with RSM, it is quite possible to determine the accurate values of the fermentation parameters where maximum production of GLA is achieved.     

油腐乳发酵过程中的品质分析

采用不同毛霉发酵油腐乳,对其发酵过程中的蛋白酶活性、成熟度、微观结构、流变和感官性质进行分析,探究不同毛霉菌种对油腐乳品质的影响。结果表明：在发酵过程中雅致放射毛霉和五通桥毛霉的蛋白酶活性最高;筛选菌种发酵的油腐乳水溶性蛋白、氨基态氮和总酸含量高于其他3 组,而菌种对油腐乳的水分和盐含量的影响不显著;筛选菌种发酵油腐乳的微观结构最致密;雅致放射毛霉发酵油腐乳涂抹性优于其他3 组;总状毛霉和雅致放射毛霉感官评价相对较优。4 种毛霉菌种各有优势,为毛霉混合发酵油腐乳提供了一定的理论依据。     

特香型大曲表面毛霉对大曲与基酒质量的影响

为控制特香型大曲表面毛霉的过度生长,在不改变传统特香型大曲制作工艺的前提下,从缩短低温培菌期和减少毛霉初始接种量两个方面对毛霉生长进行控制,从而探究毛霉生长对大曲质量和基酒质量的影响。结果表明,与对照组相比,试验组（处理一、处理二）大曲表面的毛霉生长量（19.8%、24.4%）明显减少;大曲的糖化力（822 mg/（g·h）、858 mg/（g·h））和液化力（4.00 g/（g·h）、4.80 g/（g·h））提高;基酒产量（571.7 kg、632.6 kg）无显著性差异（P＞0.05）;处理一的总酯、乙酸乙酯及丙酸乙酯含量显著升高（P＜0.05）,总酸含量及其他7个主体指标差异均不显著（P＞0.05）,基酒的综合感官评价更优。综上,控制冬春季大曲表面毛霉的生长,有助于改善大曲的外观,提高大曲和基酒的质量。     

Lipase-catalyzed synthesis of isoamyl butyrate: Optimization by response surface methodology

Immobilized lipase from Mucor miehei (Lipozyme IM-20) was employed in the esterification of butyric acid and isoamyl alcohol to synthesize isoamyl butyrate in n-hexane. Response surface methodology based on five-level, five-variable central composite rotatable design was used to evaluate the effects of important variables—enzyme/substrate (E/S) ratio (5–25 g/mol), acid concentration (0.2–1.0 M), alcohol concentration (0.25–1.25 M), incubation period (12–60 h), and temperature (30–50°C)—on esterification yield of isoamyl butyrate. In the range of parameters studied, the extent of esterification decreased with temperature, lower E/S ratios, and incubation periods. Excess acid and alcohol concentrations (i.e., acid/alcohol >1.4 or alcohol/acid >1.4) were found to decrease yield probably owing to inhibition of the enzyme by acid or alcohol, the former being more severe. The optimal conditions achieved are as follows: E/S ratio, 17 g/mol; acid concentration, 1.0 M; incubation period, 60 h; alcohol concentration, 1.25 M; and temperature, 30°C. With these conditions, the predicted value was 1.0 M ester, and the actual experimental value was 0.98 M.     

不同菌种发酵黄豆酱的氨基酸态氮的研究

通过对三种常用于黄豆酱制曲的菌种（即米曲霉、根霉和高大毛霉）制备黄豆酱,分别对三种菌的蛋白酶活性和蛋白组分以及酱醅的氨基酸态氮含量进行比较.结果表明,米曲霉的蛋白酶活力大于根霉和高大毛霉,蛋白质组分比高大毛霉和根霉的更为复杂,且米曲霉制得的黄豆酱氨基酸态氮含量较二者高.     

双霉菌混合发酵腐乳前发酵条件优化及酶活研究

八公山腐乳前发酵工艺对其总体风味具有重要影响,在总状毛霉和米根霉单独发酵腐乳的基础上,探索总状毛霉(Mucorracemosus)和米根霉(Rhizopusoryzae)混合发酵腐乳的发酵工艺。在单因素的基础上,以蛋白酶活力和糖化酶活力为评价指标,选取发酵时间、发酵温度和混合比例为影响因子,采用响应面法优化总状毛霉和米根霉混合发酵腐乳的前发酵条件,比较最优条件下混合发酵和总状毛霉与米根霉单独发酵的前发酵情况。研究结果表明总状毛霉和米根霉混合发酵的前发酵条件为:发酵时间56 h、发酵温度28℃、混合比例(总状毛霉和米根霉)1∶1,此时分泌产蛋白酶活力50.51 U/m L,糖化酶活力为15.15 U/m L。通过对比双菌和单菌发酵腐乳前发酵情况可知:总状毛霉和米根霉混合发酵较总状毛霉更能耐高温,且在菌丝的生长和酶系的分泌积累较单独发酵都更有优势,为后期发酵的一系列生化反应奠定了良好的基础,有利于改善腐乳的发酵周期,提高腐乳的品质。      

米黑毛霉酶凝干酪素生产工艺参数的优化研究

以新鲜牛乳为原料,采用米黑毛霉凝乳酶为凝乳剂,先通过单因素实验研究凝乳酶添加量、Ca Cl2添加量、凝乳p H、凝乳温度对酶凝干酪素得率的影响,然后通过响应面设计进一步优化了米黑毛霉酶凝干酪素生产工艺参数。优化得到的最佳工艺参数为:凝乳酶添加量0.49%、Ca Cl2添加量0.37 mg/m L、凝乳p H6.08、凝乳温度35℃,在此条件下酶凝干酪素的得率可达3.39%。研究结果可为米黑毛霉凝乳酶在干酪素生产中的应用提供参考。      

重组毕赤酵母产凝乳酶发酵参数优化的研究

以重组毕赤酵母GS115PJ5(含微小毛霉凝乳酶基因)为研究对象,通过单因素实验确定其最佳生长条件:培养温度30℃、培养基pH值5.2、摇床转速280r/min、培养基装瓶量5%(12.5mL/250mL)。在单因素实验的基础上通过Plackett-Burman实验筛选出培养基装瓶量、甲醇添加量、培养基pH值等3个影响重组毕赤酵母产凝乳酶的主要因素,并通过响应面实验确定三者有利于产酶的最佳值分别为13.06%、1.52%、6.15,在此条件下,凝乳酶活力达到最大值即491.7SU/mL,验证实验证明模型预测值准确、可靠。