响应面分析应用于短杆菌产酶工艺的优化

本文研究了用响应面分析法(RSM)优化短杆菌产胆固醇氧化酶的工艺，发现胆固醇添加量及超声处理时间是影响短杆菌产酶最重要的因素。在模拟优化的条件下：胆固醇为4．076g／L，吐温-80为0．2932％(v／v)，照射时间为22．361min，COD最大产量1．483U／mL。     

胆固醇氧化酶高产菌株的复合诱变选育

为进一步提高产酶水平,本实验采用超声波联合亚硝基胍的复合诱变方法处理胆固醇氧化酶产生菌(甾短杆菌),通过1mg/mL亚硝基胍和超声(200W,50kHz,35min)同时处理细胞悬液,获得一株红色突变株,其产酶活力从0.5U/mL提高到1.21U/mL,酶活提高了140%。证明该联合诱变手段对甾短杆菌产胆固醇氧化酶具有良好的诱变效果。     

Brevibacterium sp.DGCDC-82发酵罐中生产胆固醇氧化酶

用Brevibacterium sp.DGCDC-82在7L发酵罐中分批培养.分别对添加剂吐温-80、培养温度、培养基的pH、通风量和搅拌速度在胆固醇氧化酶的生产中的影响进行了研究.结果显示以上条件均对产酶有影响.在不同的发酵阶段改变发酵操作条件,发酵20 h最高酶活可达1203U/L,生产强度可达60 U/(L·h).既有效地提高了胆固醇氧化酶的产量,又防止了发酵过程中的泡沫外溢.     

超声波辅助酶解法提取食用猪油工艺优化及胆固醇脱除

为开发猪油的提取新工艺,以猪脂肪组织为原料,采用超声波辅助中性蛋白酶酶解法提取食用猪油。在单因素试验的基础上,以猪油的提取率为考察指标,采用正交试验方法研究蛋白酶添加量、酶解时间、超声波功率和超声时间对猪油提取率的影响,并通过吸附条件的优化,研究β-环糊精、羧甲基纤维素及马铃薯变性淀粉3 种吸附剂对猪油胆固醇的脱除效果。结果表明：各因素对猪油提取率的影响从大到小依次为蛋白酶添加量＞酶解时间＞超声波功率＞超声时间;超声波辅助酶解提取食用猪油的最优工艺为蛋白酶添加量550 U/g、酶解时间80 min、超声波功率720 W、超声时间120 s,在此条件下,猪油的提取率为（95.14±1.65）%;3 种吸附剂对猪油胆固醇均具有明显的吸附效果,脱除能力依次为β-环糊精＞羧甲基纤维素＞马铃薯变性淀粉。     

胆固醇氧化酶转化蛋黄胆固醇工艺的优化

研究了用响应面分析法(RSM)优化酶法转化蛋黄胆固醇的工艺,发现胆固醇氧化酶(COD)添加量及蛋黄粉的稀释率是影响蛋黄胆固醇转化率最重要的因素.在模拟优化的条件下反应时间为14.15h,蛋黄粉稀释率为3.54,COD为5.39U/g时,胆固醇转化率达85.61%.对氧化产物进行分析发现仅有单一产物胆甾烯酮,该产物具有降血脂、减肥等功效.     

酸菜来源植物乳杆菌S4-5的降胆固醇作用

对酸菜来源植物乳杆菌S4-5的体外降胆固醇作用进行研究。采用单因素试验研究胆盐添加量、胆固醇添加量、培养基初始pH值及培养时间对植物乳杆菌S4-5降胆固醇能力的影响,结果表明:在胆盐质量浓度为1.0mg/mL和胆固醇质量浓度为175.7mg/L时,植物乳杆菌S4-5有最高的胆固醇移除率,分别为67.7%和62.2%;植物乳杆菌S4-5在培养基不同初始pH值条件下对胆固醇的移除率均在71.3%～77.2%之间;培养时间对植物乳杆菌S4-5的降胆固醇作用有显著性影响(P<0.01),在培养2h(延滞期结束)、14h(指数期结束)、24h和48h后植物乳杆菌S4-5对胆固醇的移除率分别为4.8%、66.7%、75.3%和84.0%。     

全自动发酵罐小试生产胆固醇氧化酶发酵条件的研究

目的:为了将胆固醇氧化酶应用于低胆固醇系列食品开发和胆固醇测定中,研究优化了菌株Rhodococcus SP.R14-2发酵生产胆固醇氧化酶(COX)的工艺条件.方法:通过测定比较COX酶活力,利用全自动发酵罐小试生产COX,研究发酵温度、pH、乳化剂、通风量和搅拌速率等因素对COX产量的影响.结果:Rhodococcus SP.R14-2的生物生长量和产酶是部分偶联的,胞外COX酶的合成高峰比生物量高峰滞后约12h.发酵过程中分段控制搅拌转速和通气量分别为:发酵前10h,200r/min和4L/min;10～50h,300r/min和5L/min:50h后,250r/min和4.5L/min,COX达到1.58u/mL的最高量.结论:发酵温度、培养基pH、通气量及搅拌速度等因素影响其生物量和COX酶合成,采用分段式控制,有利于COX产量的提高.     

两株嗜酸乳杆菌体外降低胆固醇的研究

考察两株嗜酸乳杆菌体外降低胆固醇的降低曲线和降低方式,以及不同条件下嗜酸乳杆菌对培养基中胆固醇的降低情况.结果表明,这两株茵对胆固醇有明显的去除作用,其对胆固醇的降低作用是同化吸收和共沉淀的结果,以同化方式为主;随着接种量的增加,降低率也随之增加;不同胆盐对其降低胆固醇效果不同,当胆盐添加量为0.2％(m/V)时,胆固醇降低量最大;当吐温80添加量为0.1％时,胆固醇降低效果最佳.     

海洋中产胆固醇氧化酶细菌的筛选及其发酵条件优化

利用菌落染色法从海洋中分离、筛选高产胆固醇氧化酶的菌株,所得菌株经分子生物学技术进行鉴定,采用单因素试验对其产酶条件进行优化,并利用硫酸铵沉淀、凝胶过滤层析法对酶进行分离纯化。结果表明,以胆固醇为唯一碳源,筛选出具有高胆固醇氧化酶活性的菌株XLH059,酶活力为0.407 U/m L;菌株XLH059被鉴定为蜡样芽孢杆菌(Bacillus cereus);菌株XLH059的最佳产酶条件为发酵周期24 h,发酵温度26℃,接种量10%,初始pH值7.0,装液量100 m L/250 m L,转速200 r/min,最佳碳源和氮源分别为葡萄糖和蛋白胨,胆固醇含量0.5%。在此优化条件下,胆固醇氧化酶活力为0.72 U/m L,是优化前的1.76倍;经分离纯化获得分子质量约为59 kDa的胆固醇氧化酶。     

一株产胆固醇氧化酶酵母菌的鉴定及发酵条件优化

从富含胆固醇环境的土壤等中进行采样,经富集培养后,以胆固醇为单一碳源的筛选培养基进行筛选,得到不同形态的5株菌株。挑选产酶量最高的一株进行菌种鉴定,并对其发酵产酶条件进行优化。结果表明,该高产胆固醇氧化酶菌株属于季也蒙毕赤酵母属(P.guilliermondii)。其最适发酵培养基组成为:玉米淀粉0.7%,酵母膏1.5%,胆固醇0.2%,吐温801%;理想的培养条件为:培养基pH7.5,37℃条件下培养,装液量为75mL于250mL三角瓶中。优化发酵条件后产酶量达到3501U/L,比发酵前提高了1.5倍。     

胆固醇氧化酶法脱除食品中胆固醇的研究进展

综述了利用胆固醇氧化酶脱除食品胆固醇的国内外研究现状，重点评价了在不同反应条件下该酶降低蛋黄、乳、猪油等食品中的胆固醇的效果和在食品中应用的安全性，并针对这些研究的成果提出了今后这一研究领域尚需解决的主要问题。     

一株胆固醇氧化酶产生菌株的筛选和鉴定

从腐败的猪油中筛选出一株产胆固醇氧化酶的菌株P3,通过形态学、生理生化条件和16srRNA鉴定,确定该茵为类芽孢杆菌,命名为Paenibacillus sp P3。     

转化胆固醇的微生物在食品中的应用研究

介绍体内胆固醇过量的危害及防治对策,对采用生物方法降低食品中胆固醇进行了详细的概述,对该领域的应用前景及研究方向做了展望。     

比色法测定胆固醇氧化酶酶活

根据实验结果和理论计算确定检测体系中胆固醇的质量浓度为 0 .3 87mg/mL ,表面活性剂的质量浓度为 0 .2 g/dL ,确定过氧化氢浓度与反应液吸光度之间的定量关系 .在此基础上 ,建立了比色法测定胆固醇氧化酶酶活的方法 .     

Cholesterol Oxidation in Fish and Fish Products

Fish and fish products are important from a nutritional point of view due to the presence of high biological value proteins and the high content of polyunsaturated fatty acids, especially those of the n‐3 series, and above all eicosapentaenoic acid and docosahexaenoic acid. However, these important food products also contain significant amounts of cholesterol. Although cholesterol participates in essential functions in the human body, it is unstable, especially in the presence of light, oxygen, radiation, and high temperatures that can cause the formation of cholesterol oxidation products or cholesterol oxides, which are prejudicial to human health. Fish processing involves high and low temperatures, as well as other methods for microbiological control, which increases shelf life and consequently added value; however, such processes favor the formation of cholesterol oxidation products. This review brings together data on the formation of cholesterol oxides during the preparation and processing of fish into food products which are recognized and recommended for their nutritional properties.     

低胆固醇发酵肉制品的研究与开发

本文着手于胆固醇的危害和低胆固醇发酵肉制品研发的意义，对于目前国内外乳酸菌发酵降低胆固醇的现状与趋势进行了分析和阐述；并同时提出了现存的问题。表明低胆固醇发酵肉制品研发的具有现实的可行性。     

Oxidation of Cholesterol in Foods and Its Importance for Human Health

Cholesterol oxidation products are present in different biological pathways and in oxidized cholesterol-containing food. More than 70 molecules have been identified and most of them present cytotoxic, atherogenic, mutagenic, and carcinogenic effects. They can change important characteristics of the cellular membrane and inhibit the biosynthesis of several molecules. Foods of animal origin can develop these derivatives by the action of oxygen, heat, polyunsaturated fatty acids, water, pH, radiation, and inadequate packaging and storage, affecting their quality and exposing consumers to potential health problems. Despite the interest in cholesterol oxidation products, safe biological levels for them have not yet been established. The purpose of this review is to examine cholesterol oxidation products in foods and examine their importance for human health.     

Enzymatic Determination of Cholesterol Oxides

For measurement of the concentration of oxidised cholesterols in foodstuffs, a method was developed by adapting the well-known enzymatic determination of cholesterol. A linear correlation was found between the absorbance measured after enzymatic reaction and the concentrations of 7α-hydroxycholesterol, 7β-hydroxycholesterol, 7-ketocholesterol, cholesterol-5α, 6α-epoxide in the range 1–12 μg. The usefulness of this method was demonstrated by determination of the four cholesterol oxidation products separated by TLC from the non-saponifiable lipid fraction of 5-month-old whole-egg powder (stored under different conditions) and of biscuit enriched with egg powder. The main advantages of the combination of TLC and the enzymatic method, beyond its rapidity and sensitivity, are that the determination of cholesterol oxidation products can be carried out in parallel with many samples containing small amounts of oxidised cholesterols even in the presence of a large quantity of cholesterol.