β-环糊精脱除蛋黄中胆固醇工艺的优化

为优化β-环糊精包合法对蛋黄中胆固醇脱除的工艺条件,提高脱除率,选用3因素3水平的二次通用旋转设计,以稀释倍数、β-环糊精添加量、混合温度为影响因素,以胆固醇脱除率为响应值,建立回归模型。结果表明:各因素对蛋黄胆固醇脱除率的影响大小顺序为,β-环糊精添加量﹥稀释倍数﹥混合温度。胆固醇脱除的最佳工艺参数为,稀释2.67倍,β-环糊精添加的质量分数为19.33%,混合温度48.89℃,在此条件下,蛋黄胆固醇脱除率的理论值为89.82%,验证试验值为89.01%。     

SC-CO2的萃取装填系数和时间对蛋黄粉中胆固醇脱除效果的影响

着重研究了装填系数和萃取时间对超临界二氧化碳(SC-CO2)萃取蛋黄粉中胆固醇的影响。结果表明,在萃取温度为40℃,萃取压力为30MPa时,随着装填系数的减少和萃取时间的增加,蛋黄粉的产率降低,脂肪含量和胆固醇含量降低,脂肪脱除率和胆固醇脱除率增加。在超临界二氧化碳脱除胆固醇的过程中,萃取时间是影响蛋黄粉中脂肪和胆固醇脱除的主要因素。在实际中,可以采用增加装填系数和适当延长萃取时间的方法来降低蛋黄粉中胆固醇含量,并可以提高蛋黄粉产率。     

β-环状糊精脱除蛋黄中胆固醇的扩大试验

进行了β 环状糊精脱除鸡蛋中胆固醇工艺的研究 .在实验室规模进行了工艺参数的优化 ,以较低的环状糊精添加量 (1 5% ) ,获得较高的蛋黄中胆固醇的去除率 (85% ) ;同时保证低胆固醇蛋制品具原蛋黄的营养价值和功能性质 .在此基础上扩大试验规模 ,调整工艺参数 ,研制出适于工业化生产低胆固醇蛋制品的最佳工艺 .     

超临界萃取法与环糊精法脱除蛋黄中胆固醇效果的比较

研究应用环糊精法和超临界萃取法脱除胆固醇的蛋黄粉分别制作了低胆固醇蛋黄酱。结果表明 ,由于β-环糊精在脱除蛋黄中胆固醇的同时 ,也脱除了较多的磷脂成分 ,降低蛋黄的乳化能力 ,因此 ,用它制作的蛋黄酱表观粘度较低 ,感官品质较差 ;而超临界萃取法能选择性脱除蛋黄粉中胆固醇 ,保留了较多的磷脂和蛋白质成分 ,因此 ,用它制作的蛋黄酱具有良好的物理状态和感官品质。由此可以证明 ,超临界萃取法脱除胆固醇的效果明显好于 β-环糊精法 ,是脱除食品中胆固醇的理想手段。     

氧化反应中胆固醇与甘油酯相互作用

<正> 前言研究表明胆固醇和甘油酯的氧化产物对人体有害。最近采用新的色谱分析手段,能分离和鉴别出多种胆固醇的氧化产物,例如在煎炸的鸡肉中检测出6—53ppm胆固醇的环氧化物;在干燥的蛋黄粉中检测出7-羧基胆固醇(74ppm),7-酮     

β-环糊精脱除蛋黄中胆固醇的研究

研究了β-环状糊精(β-CD)包合法脱除鸡蛋蛋黄中胆固醇,应用DX7Trial对试验数据进行分析并建立了数学模型,得出了胆固醇脱除的最佳工艺为:pH10.5,加热温度50.18℃,搅拌时间10.94min,n(β-CD):n (蛋黄液中胆固醇)=4.11:1,在此条件下,胆固醇脱除率为92.23%,产品中胆固醇含量为0.7536mg/g。     

干酪乳杆菌21008体外降胆固醇活性研究

用胆固醇氧化酶指示平板和测定胆固醇氧化酶活力的方法对干酪乳杆菌21008是否具有产生胆固醇氧化酶的能力进行了研究,并以添加胆固醇的MRS培养基和蛋黄对菌株降胆固醇能力进行了评价。结果发现干酪乳杆菌能产生胆固醇氧化酶类似物,并且测得胞内酶活为302.7U/L,但没有胞外酶。菌株使MRS-CHO培养基中的胆固醇降低69.5%,主要是通过菌体细胞吸收、转化作用;而在蛋黄中发酵,优化条件下:V蛋黄∶V水=2∶1,接种量8%,发酵30h,胆固醇降低16.82%,pH降为5.57。     

β-环状糊精包合法脱除胆固醇对蛋黄卵磷脂及其功能性质的影响研究

研究了β-环状糊精包合法脱除鸡蛋黄胆固醇工艺对卵磷脂物质及蛋黄功能性质的影响。高效液相色谱（HPLC）检测结果表明，利用该法脱除蛋黄中90％以上的胆固醇时，蛋黄卵磷脂物质损失不超过8．0％。与普通蛋黄粉相比，起泡性能增强但色泽略浅，乳化稳定性略有下降。     

超临界二氧化碳的萃取压力和时间对蛋黄粉中胆固醇脱除的影响

研究了在萃取温度为40℃时,超临界二氧化碳的萃取压力（20～30MPa）和萃取时间（1～4h）对蛋黄粉中胆固醇脱除效果的影响。试验结果表明,在萃取压力为30Mpa时,超临界二氧化碳对蛋黄粉中胆固醇的选择性脱除作用效果最佳。从蛋黄粉成分在萃取过程中的动态变化来看,萃取时间不改变萃取压力对胆固醇的选择性;但是,随着萃取时间的延长,胆固醇的脱除率会大大增加。     

邻苯二甲醛(OPA)法快速测定蛋黄粉中的胆固醇含量

研究用邻苯二甲醛(OPA)法测定蛋黄粉中胆固醇含量.结果表明,OPA法变异系数为2.89%,精密度高,回收率较高,适于胆固醇含量的快速测定,具有操作简单、方法稳定等特点.同时,用甲醇氯仿法提取胆固醇,方法准确、简单易行.     

Bioconversion of yolk cholesterol by extracellular cholesterol oxidase from Brevibacterium sp.

An efficient process for reducing yolk cholesterol by enzymatic treatment was developed in this paper. Extracellular cholesterol oxidase (COD) from a mutant Brevibacterium sp. ODG-007, showed a strong capacity in bioconversion of yolk cholesterol to cholest-4-en-3-one, especially supplemented with NaCl and lipase C, as a yolk granule solubilizer. The bioconversion process was investigated first, to obtain basic information of the process and was further optimized by analysis of parameters, including COD concentration, dilution ratio and incubation time on the cholesterol conversion, employing Response Surface Methodology (RSM) and Central Composite Design (CCD). Under the optimum operational conditions: COD concentration of 5.39 U/g yolk powder, water: solid ratio of 3.54 and incubation time of 13.75 h, up to 85.6% yolk cholesterol was reduced, and the remaining cholestenone, an effective anti obesity medicine in the product, may raise its commercial value.     

Cholesterol Reduction in Liquid Egg Yolk using β-Cyclodextrin

A process to reduce cholesterol in liquid egg yolk using β-cyclodextrin (CD) was optimized by response surface methodology, based on cholesterol reduction and yield. The most important factors influencing cholesterol reduction were dilution of egg yolk to a defined water:solid ratio and CD concentration. In the final process, egg yolk was adjusted to pH 10.5, diluted to a water:solid ratio of 2.9, heated to 50°C, and CD added at a CD:cholesterol molar ratio of 4.0. The slurry was mixed for 6.5 min at 1800 rpm, cooled to 4°C and centrifuged. Cholesterol in the supernatant was reduced by 89.2%. The yield, cholesterol and CD in the final product were adjusted by varying centrifugal force and CD concentration.     

复合乳酸菌发酵降低蛋黄液中胆固醇的工艺优化

为降低蛋黄液中胆固醇含量,选择出降胆固醇效果较好的3 种菌作为复合发酵菌种,将复合菌株接种到蛋黄液中,于恒温培养箱中培养,用直接皂化-比色法探讨了复合乳酸菌对蛋黄液中胆固醇降低率的影响,利用正交试验优化最佳发酵工艺参数。结果表明,最佳工艺条件为发酵温度40 ℃、发酵时间24 h、接种量3%、牛胆盐质量浓度3 g/L、混合菌种（嗜热链球菌、嗜酸乳杆菌、双歧杆菌）菌液体积比1∶2∶1,在此条件下,可使蛋黄中胆固醇降低率达31.5%。     

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。     

乳糖诱导重组大肠杆菌表达胆固醇氧化酶的研究

采用乳糖诱导胆固醇氧化酶(COD)基因在大肠杆菌BL21(DE3)中表达,研究了培养基成分、乳糖浓度、诱导时间和诱导温度对胆固醇氧化酶表达的影响。结果显示,在对诱导条件进行优化控制的前提下,胆固醇氧化酶酶活达到15.2 U/mL。研究结果为乳糖作为诱导剂最终应用于重组基因工程药物的工业化生产提供了有益的参考和借鉴。     

Effects of dietary taurine on egg production,egg quality and cholesterol levels in Japanese quail

BACKGROUND: Taurine is a semi‐essential amino acid and has many biological properties. The objective of this study was to determine the effect of dietary supplementation with taurine on egg production, egg quality, and cholesterol level in serum and egg yolk of quails. A total of 108 quails aged 6 weeks were randomly allocated to three dietary treatments. Each treatment consisted of four replicates of nine quails. The diets were supplemented with 0, 100, and 500 mg kg^?1 of taurine for 8 weeks. RESULTS: Dietary 500 mg kg^?1 taurine significantly affected egg production rate and feed conversion ratio, but had no significant effects on body weight gain, feed consumption, or egg weight. Dietary taurine had no significant effect on egg quality parameters studied. Serum triglyceride concentration was reduced significantly with supplementation of taurine at 100 and 500 mg kg^?1. Egg yolk cholesterol content was reduced significantly, and the contents of serum taurine and egg yolk taurine were increased significantly with taurine supplementation at 500 mg kg^?1. CONCLUSION: Results of the present study indicated that adding 500 mg kg^?1 taurine reduced yolk cholesterol concentration and increased yolk taurine content without adverse effects on performance and egg quality of laying quails. Copyright © 2010 Society of Chemical Industry     

Cholesterol Oxidation in Egg Yolk Powder During Storage and Heating as Affected by Dietary Oils and Tocopherol

The effects of feeding flax, sunflower, palm and fish oils, with and without tocopherols, to laying hens was investigated on oxidative stability of cholesterol in egg yolk powders. Storage of spray-dried egg yolk powders at room temperature resulted in loss (p <0.05) of tocopherols. The initial levels of spray-dried yolk cholesterol oxides were 7–10 ppm and increased (p <0.05) with storage. The cholesterol oxide contents in the egg yolk powders were: fish > flax > sunflower > palm. Heating egg yolk powder increased (p <0.05) the amounts of total cholesterol oxides. Diets with tocopherol supplementation resulted in a decrease (p <0.05) of cholesterol oxides during storage and heating.     

不同饲料喂养鸡蛋中胆固醇的含量测定

对A,B,C,D四组不同饲料喂养新鲜鸡蛋的胆固醇含量进行测定,比较鸡蛋的平均重量、蛋清相对重量、蛋黄相对重量、蛋壳相对重量、蛋壳厚度.筛选出胆固醇含量较低的营养保健型鸡蛋.结果表明:A、B组的胆固醇含量偏高.C和D组的胆固醇含量较低,所有其他检测指标基本上没有差异.综合营养和经济因素,D组的鸡蛋更适宜于加工生产.     

Ultrasonic-assisted enzymatic degradation of cholesterol in egg yolk

An ultrasonic-assisted enzymatic process was developed for effective degradation of cholesterol in natural egg yolk. The objective of this study was to follow the catalytic activity of cholesterol oxidase against egg yolk cholesterol in an effort to obtain a cholesterol reduced egg yolk without affecting the major nutrients composition of egg yolk. Cholesterol oxidase was used to catalyze the degradation of cholesterol in egg yolk. Firstly, a 30 g portion of the egg yolk was pretreated by ultrasonic for 15 min at 200 W and then incubated for 10 h with cholesterol oxidase concentration of 0.6 U/g egg yolk at 37 °C. Finally, the cholesterol level in egg yolk was reduced to 8.32% of its original concentration without affecting the quality attributes of the yolk.

Industrial relevance

With the increase of public awareness to the dangers of cholesterol in recent years, a large number of popular food products have drawn criticism for containing high levels of cholesterol. Many reduced cholesterol egg products have been developed for market requirement. The results indicate that the ultrasonic-assistant extraction is an effective method for effective degradation of cholesterol in natural egg yolk. The knowledge gained from this study should be useful for further exploitation and application of the resource. Cholesterol-reduced egg yolk promises to be a value-added functional food with all the health enhancing attributes associated with egg yolk.