红曲霉对胆固醇降解特性的研究

研究了20株在含有胆固醇的培养基(PDAO-CHOL)中生长的红曲霉对胆固醇的降解特性,结果表明,供试的20株红曲霉均具有降解胆固醇的能力,其中M3、M16、E5、15-1、E4和M2菌株对胆固醇降解率均超过50%,且对胆固醇的降解率随培养时间的延长而增加.各菌株最佳接种量为8%,培养基最佳胆固醇浓度为0.5mg/mL,此条件下各菌株的胆固醇降解率均达到最高,其中M3菌株对胆固醇的降解率最高,达到74.93%.     

新疆自然发酵骆驼酸乳中乳酸菌降解胆固醇能力研究

以新疆骆驼酸奶分离出的10株初步鉴定为乳酸菌的菌株为研究对象,进行体外胆固醇降解能力的研究。用富集培养方法筛选出具有降解胆固醇能力的乳酸菌,然后将菌株接种到发酵培养基中进行发酵产酶,离心得酶液,用分光光度法测定其酶液对胆固醇的降解率,进而分析研究各菌株降解胆固醇的能力。有9株乳酸菌能够在以胆固醇为唯一碳源和能源的液体培养基中生长,其中3株菌对胆固醇降解率达到了60%。实验通过对自然发酵的骆驼酸乳中分离得到的乳酸菌的体外降解胆固醇的实验研究,表明骆驼酸乳中的乳酸菌具有一定的降解胆固醇的能力。     

降胆固醇红曲霉菌株的分离及其降解性能研究

以红方豆腐乳为菌源材料,经含有乙醇和链霉素的麦芽汁培养基富集和平板分离,得到一株降胆固醇的红曲霉（Monascus）菌株X2,对菌株的形态结构特征进行了观察。通过初筛和胆固醇降解试验研究表明,X2菌株具有较强的降胆固醇能力,在32 ℃摇床发酵6 d,胆固醇降解率可达60.82%。     

胆固醇氧化酶降解鸭肠中胆固醇的工艺条件研究

目的:研究用胆固醇氧化酶降解鸭肠中胆固醇,为拓宽鸭肠的应用范围提供参考。方法:分光光度法。结果:通过单因素研究和响应曲面法分析,得到酶解胆固醇的最佳条件是,当料液比为1∶10时,酶解pH为7.08,酶解时间为3.04h,酶解温度为25℃,酶用量为0.12U/g,鸭肠中胆固醇的降解率达36.76%。结论:胆固醇氧化酶可有效降解鸭肠中胆固醇且感官品质基本不变。     

乳酸菌代谢产物降解胆固醇作用研究

通过胆盐水解酶(BSH)定量分析、静态体外消化分析、模拟动态消化分析及不同阴离子对乳酸菌降解胆固醇的效果分析，研究乳酸菌代谢产物对胆固醇的降解作用。结果表明：LR-ZRX01、LA-ZRX02、LP-ZRX03体外胆固醇降解率分别为25.61%±1.25%、28.87%±2.16%、20.39%±1.84%,唾液静态体外消化后胆固醇降解率分别为27.35%±2.35%、34.28%±2.41%、23.53%±1.98%,胃液静态体外消化后胆固醇降解率分别为26.95%±1.56%、30.51%±2.35%、22.27%±1.15%,动态模拟消化后食糜排空泵中胆固醇降解率分别为16.22%±1.05%、20.22%±2.82%、14.78%±1.12%,仿生胃中胆固醇降解率分别为13.98%±1.13%、16.84%±1.28%、15.15%±2.04%,BSH比酶活分别为(0.388 7±0.003 9)、(0.380 1±0.006 8)、(1.216 9±0.008 3)U/mg。添加适量浓度的Cl^-、NO₃^-、SO...     

高效降解胆固醇菌株的筛选及其在食品中的应用

目的:为开发低胆固醇系列食品,从多种富含胆固醇的动物性发酵食品中分离、筛选高效降解胆固醇的菌株。方法:将采集的25种样品,选择培养基Ⅰ连续传代培养,通过比较胆固醇降解率和酶活力,筛选出降解胆固醇能力较高的菌株,并研究其酶学特性。结果:筛选出的红球菌(Rhodococcussp.)R14-2和短杆菌(Brevibac-teriumsp.)R22-4对胆固醇底物溶液的降解率分别为97.5%和94.7%;对鲜肉糜中胆固醇的降解率分别为41.3%和40.5%,并在低温(0～10℃)时仍表现出一定的酶活性;将这两种菌株的粗酶液应用于乳、蛋及香肠制作中,降胆固醇效果明显且未见有不良风味。结论:利用酶法生物降解食品中胆固醇,不仅产物单一,而且对食品风味、营养的影响较小,适于开发低胆固醇系列食品。     

乳杆菌体外降解胆固醇特性研究

以实验室自主分离纯化的鼠李糖乳杆菌zxr01、嗜酸乳杆菌zrx02、植物乳杆菌zrx03, 3株乳杆菌体外降解胆固醇的特性以及不同金属阳离子对其影响进行了研究。嗜酸乳杆菌、鼠李糖乳杆菌、植物乳杆菌体外胆固醇降解率分别为28.87%、25.61%、20.39%；当pH为3时，3株乳杆菌耐酸性分别为：52.77%、52.57%、59.82%;牛胆盐浓度为0.3%时胆盐耐受性为28.65%、27.40%、26.04%；嗜酸乳杆菌在氯仿中的疏水性最好，达到了19.88%，静置24 h后，嗜酸乳杆菌和植物乳杆菌的自凝聚力都达到了80%以上且3株乳杆菌产生白色沉淀说明能产生胆盐水解酶，在Ca2+浓度为0.02 N时，嗜酸乳杆菌的胆固醇降解率为35.4%和降解效果65.43μg/u。结果显示3株乳杆菌均能在体外降解胆固醇，嗜酸乳杆菌的降解胆固醇的能力要优于其它两株乳杆菌，添加浓度为0.02 N的Ca2+可以促进嗜酸乳杆菌胆固醇降解率和降解效力。本研究结果可为进一步研究胆固醇降解提供了试验依据，为开发降胆固醇食品提供材料。     

降胆固醇乳酸菌的筛选

实验从泡菜中筛选出了13株乳酸菌,并对其胆固醇降解能力进行研究.结果表明:培养时间为3 d、接种量为5%、胆固醇浓度为1 mg/mL时胆固醇降解量最大,其中编号为HLB01具有最高的胆固醇降解量,达到了97.01μg/mL;筛选出的乳酸菌菌株均有降解胆固醇的能力,而其中多数为乳球菌.     

东北传统发酵食品中降胆固醇乳酸菌的筛选及其降解机制

从中国东北传统发酵食品黏面子、辣白菜、辣酱中筛选具有高效降解胆固醇作用的乳酸菌,并探讨其主要的降解机制。采用体外实验筛选出高效降胆固醇的乳酸菌菌株,进一步研究了其降胆固醇的作用机制,包括细胞膜的吸附、胆汁盐水解酶基因表达及酶活性、胆汁酸共沉淀胆固醇以及抑制胆固醇胶束形成等。筛选得到6 株高胆固醇清除能力的菌株C1、C2、H6、H9、L22和L30,清除率均在85%以上。受试菌株均可以通过膜吸附、共沉淀、胆汁盐水解酶作用和抑制胆固醇胶束等机制发挥作用,其中以胆汁盐水解酶的作用为主要机制。     

柳州酸笋中降胆固醇乳酸菌的筛选及鉴定

为了获得柳州酸笋源的优良乳酸菌,利用MRS-CaCO_3培养基分离纯化来自柳州的传统酸笋发酵液中的乳酸菌,然后采用硫酸铁铵显色法对降胆固醇乳酸菌进行筛选,再用16S rDNA测序法鉴定菌种,最后探讨影响菌株降解胆固醇能力的因素。结果表明,在分离得到的48株乳酸菌中,菌株LZ-2-12具有较高的降胆固醇能力,其胆固醇降解率达54.27%,经形态和分子生物学鉴定其为植物乳杆菌(Lactobacillus plantarum);该菌株在以葡萄糖为碳源(20 g/L)、细菌学蛋白胨为氮源(10 g/L)、接种量为3.0%、pH值为7.0、温度为37℃的条件下,降解胆固醇效果较好。该研究菌株可作为发酵剂,为益生菌功能食品们的开发提供基础。     

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。      

Choosing hamsters but not rats as a model for studying plasma cholesterol‐lowering activity of functional foods

Rats and hamsters are commonly used rodents to test the efficacy of cholesterol‐lowering functional foods. In general, a diet containing 1% cholesterol for rats whereas a diet containing 0.1% cholesterol for hamsters is used to induce the hypercholesterolemia. The present study was carried out to compare hamsters with rats as a hypercholesterolemia model. Golden Syrian hamsters and Sprague Dawley rats were randomly divided into four groups and fed one of the four diets containing 0–0.9% cholesterol. Results demonstrated that serum total cholesterol (TC) in hamsters was raised 73–81% higher than that in rats fed the same cholesterol diets. Unlike rats in which HDL‐C accounted very little for serum TC, the lipoprotein profile in hamsters was closer to that in humans. We investigated interaction of higher cholesterol diets with 3‐hydroxy‐3‐methylglutary‐CoA (HMG‐CoA) reductase, low‐density lipoprotein receptor (LDL‐R) and cholesterol‐7α‐hydroxylase (CYP7A1), sterol regulatory element binding protein‐2 (SREBP‐2), and liver X receptor (LXR‐α). Results showed hamsters and rats metabolized cholesterol differently. In view that hamsters synthesize and excrete cholesterol and bile acids in a manner similar to that in humans, it is concluded that hamsters but not rats shall be chosen as a model to study efficacy of cholesterol‐lowering functional foods.     

Antihyperlipidemic effect of sesame (Sesamum indicum L.) protein isolate in rats fed a normal and high cholesterol diet

The dietary influence of sesame protein isolate (protein content 91.5%), produced from dehulled, defatted sesame meal, on blood and tissue lipid profile and lipid peroxidation has been assessed in normal and hypercholesterolemic rats. To evaluate their hypocholesterolemic and antioxidative activity in vivo, we fed 18% sesame protein isolate with or without 2% cholesterol in comparison with casein to rats for 28 d. We determined plasma total protein, total cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, triacylglycerol as well as susceptibility of plasma and erythrocyte membrane lipid to oxidation ex vivo. Liver tissue lipid, cholesterol, phospholipids, and lipid peroxidations were also determined. The total cholesterol, LDL-cholesterol and triacylglycerol levels were significantly reduced in the sesame protein isolate and isolate containing cholesterol group than the corresponding control casein groups. HDL-cholesterol level was also increased in sesame protein isolate (41%) and protein isolate containing cholesterol group (38%) than the corresponding control casein and casein containing cholesterol groups. There was 49% and 64% lowering of plasma lipid peroxidation as well as 36% and 56% lowering of lipoprotein oxidation susceptibility (LOS) in the 2 experimental groups (sesame protein isolate and isolate containing cholesterol group) than the corresponding control (casein and casein containing cholesterol) groups. There was significant lowering of erythrocyte membrane lipid peroxidation (68% and 63% lowering in sesame protein isolate and isolate containing cholesterol groups) and liver lipid peroxidation (61% and 76% lowering in the 2 experimental groups than the corresponding control casein groups). Therefore, our results indicate that sesame protein isolate decreases cholesterol concentration in plasma, increases HDL-cholesterol, and also decreases plasma and erythrocyte membrane lipid peroxidation with or without cholesterol fed diet in rats.     

Influence of Surface Structure on Cholesterol Oxidation in Model Food Powders

Three milk-resembling powders having different oil phases were prepared and stored for six months at room temperature. Samples were taken monthly for estimation of the surface composition by ‘electron spectroscopy for chemical analysis’ (ESCA) and analyses of the level of cholesterol oxides by gas chromatography. The highest fat coverage was obtained with technical tristearin as the oil phase. This preparation had around 75% of the powder surface covered by fat; during storage this coverage decreased. This powder also had the largest increase in cholesterol oxides during storage, the final level being 159 μg g⁻¹ cholesterol. The powder containing high-melting pure tristearin had a low surface coverage of fat, originally about 25%, which decreased during the storage period. Little increase in cholesterol oxides was observed, the final level being 52 μg g⁻¹ cholesterol. The third powder containing liquid triolein as oil phase, had a surface coverage of about 50% throughout the storage period. The cholesterol oxidation rate was in between that of the two tristearin powders, the final level of oxides being 75 μg g⁻¹ cholesterol. The results for the investigated powders indicate that the surface composition is of major importance for the oxidation of cholesterol. No correlation between cholesterol oxidation and solvent extractable fat (free fat) was found.     

Optimizing cholesterol removal from cream using β-cyclodextrin cross-linked with adipic acid

The present study was carried out to optimize the different conditions for cross-linked β-cyclodextrin (β-CD) using adipic acid on cholesterol removal in cream. Different factors were β-CD concentration, mixing temperature, mixing time and mixing speed. Cross-linked β-CD was prepared with adipic acid. When the cream was treated with 10% cross-linked β-CD, cholesterol removal was the highest at 90.7%, which was not significantly different from treatments with 15% and 20% cross-linked β-CD. Cholesterol removal was significantly influenced by mixing temperature, mixing time and mixing speed. After cholesterol removal from cream, the used cross-linked β-CD was washed for cholesterol dissociation and reused. For recycling study, the cholesterol removal in first trial was 91.5%, which was mostly same as that using new cross-linked β-CD. However, after 10 repeated trials using the same sample, only 83.4% of the cholesterol was removed from cream. Therefore, the present study indicated that the optimum conditions for cholesterol removal using cross-linked β-CD were 10%β-CD addition, 30 min mixing with 1400 r.p.m. speed at 40°C with over 90% cholesterol removal. In addition, recycled β-CD cross-linked with adipic acid showed a similarly high recycling efficiency to unused β-CD of about 90% up to the seventh trial.     

降血脂鼠李糖乳杆菌的筛选及其对高脂模型地鼠血脂的影响

该实验旨在筛选出一株具有较强降血脂功能的乳杆菌。试验采用的菌株分离自健康婴儿肠道,通过邻苯二甲醛比色法测定菌株降胆固醇能力、单试剂法测定降甘油三酯能力,并测定了其对酸及胆盐的耐受性,从中筛选出具有降胆固醇和降甘油三酯功能较强的菌株进行16S rDNA鉴定。通过建立高血脂地鼠模型,研究菌株体内降血脂能力。结果表明,鼠李糖乳杆菌HCS01-013的降胆固醇和甘油三酯能力较强,其胆固醇降解率达到35.40%;甘油三酯降解率达到44.32%;在0.3%和1.5%的胆盐环境下培养17 h的存活率分别为99.67%和96.79%,在pH 3.0和pH 2.0环境下培养17 h后存活率能达到88.76%和71.34%;黄金地鼠喂养高脂饲料建立的高脂地鼠模型后,喂养鼠李糖乳杆菌HCS01-013各剂量组与喂养生理盐水的模型对照组相比甘油三酯含量均明显降低。鼠李糖乳杆菌HCS01-013具有一定的降血脂功能,且耐逆环境能力较强,为该菌株相关研究及产品研发提供理论依据。     

Fish protein decreases serum cholesterol in rats by inhibition of cholesterol and bile acid absorption

Fish protein has been shown to decrease serum cholesterol content by inhibiting absorption of cholesterol and bile acid in laboratory animals, though the mechanism underlying this effect is not yet fully understood. The purpose of this study was to elucidate the mechanism underlying the inhibition of cholesterol and bile acid absorption following fish protein intake. Male Wistar rats were divided into 2 dietary groups of 7 rats each, 1 group receiving a diet consisting of 20% casein and the other receiving a diet consisting of 10% casein and 10% fish protein. Both experimental diets also contained 0.5% cholesterol and 0.1% sodium cholate. After the rats had been on their respective diets for 4 wk, their serum and liver cholesterol contents and fecal cholesterol, bile acid, and nitrogen excretion contents were measured. Fish protein consumption decreased serum and liver cholesterol content and increased fecal cholesterol and bile acid excretion and simultaneously increased fecal nitrogen excretion. In addition, fish protein hydrolyzate prepared by in vitro digestion had lower micellar solubility of cholesterol and higher binding capacity for bile acids compared with casein hydrolyzate. These results suggest that the hypocholesterolemic effect of fish protein is mediated by increased fecal cholesterol and bile acid excretion, which is due to the digestion products of fish protein having reduced micellar solubility of cholesterol and increased bile acid binding capacity.     

Supplementation of prebiotics to a whey-based beverage reduces the risk of hypercholesterolaemia in rats

Fructooligosaccharide-supplemented whey drinks may have potential as an interventional strategy for lowering cholesterol and triglyceride levels in dyslipidaemic conditions. A bioefficacy study was conducted in normal, hypercholesterolaemic and hyperglycaemic Sprague Dawley rats, running two consecutive trials for validity of results. Control drink (T₀), whey drink (T₁) and whey drink supplemented with 1.5% fructooligosaccharides (T₄), were given to each group. The functional drink caused a significant reduction in serum total cholesterol, low density lipoprotein (LDL) and triglycerides, and an increase in high density lipoprotein. The greatest decline in total cholesterol was induced by T₄ (10.9% and 12.0% in hypercholesterolaemic rats and 7.0% and 7.7% in hyperglycaemic rats, for trials 1 and 2, respectively). The decrease in total cholesterol by T₄ was mainly due to a pronounced decrease in LDL cholesterol (14.7% and 16.1% in hypercholesterolaemic rats and 7.4% and 8.1% in hyperglycaemic rats for trials 1 and 2, respectively).     

Effect of oyster mushroom (Pleurotus Ostreatus) and its ethanolic extract in diet on absorption and turnover of cholesterol in hypercholesterolemic rat

The effect of the diet containing 5% of powdered oyster mushroom (Pleurotus ostreatus) or an equivalent amount of mushroom ethanolic extract on cholesterol content in serum and liver, on its distribution in lipoproteins, absorption and turnover was studied in male Wistar rats (initial body weight about 70 g) fed a diet with 0.3% cholesterol. 12 weeks of feeding with whole oyster mushroom or mushroom extract reduced cholesterol level in serum by 52 and 33%, respectively. However, cholesterol content in liver was reduced only by whole oyster mushroom (by 20%). Diminished serum cholesterol level was mediated in 60% by reduction of cholesterol in very-low-density lipoproteins. Both whole oyster mushroom and mushroom extract increased the concentration of cholesterol in high-density lipoproteins. Consuming whole oyster mushroom decreased cholesterol absorption (estimated by dual-isotope plasma ratio method) by nearly 16% while no significant effect of mushroom extract could be demonstrated. Feeding the diet containing whole oyster mushroom or its extract reduced the half-times of decay curve of cholesterol-4-¹⁴C by 29 and 35%, respectively and reciprocally increased the fractional catabolic rate of plasma cholesterol.