食品加工对植物甾醇影响

本文论述植物甾醇天然来源、存在形式及食品加工对其影响,以利于控制食品加工条件,最大限度地使甾醇得以保留。     

粉末甾醇酯制备工艺研究

研究喷雾干燥法制备粉末甾醇酯工艺。研究结果表明,粉末甾醇酯最优乳化条件为:复合乳化剂配比(单甘油酯∶蔗糖酯)为1∶9、乳化剂用量0.75%、壁材用量20%、壁材比(辛烯基琥珀酸酯化淀粉∶麦芽糊精)为1∶5、芯材与壁材比为0.5。喷雾干燥法制备粉末甾醇酯最佳工艺参数为:进料温度50℃~60℃、均质压力50 MPa、进风温度180℃、出风温度80℃、喷雾压力180 KPa;在此工艺条件下,微胶囊化率可达77.8%。     

植物油中总甾醇测定前处理方法的研究

通过研究甾醇酯的皂化条件,确立了植物油中总甾醇测定的前处理方法.其重复测定结果的相对标准偏差仅为0.46%,人员之间重复测定结果的相对标准偏差在0.31%-0.58%之间,实验室间结果稳定性也较好,最大的相对标准偏差为6.26%,回收率在95.02%-104.29%范围内,适用于植物油中总甾醇的测定.     

植物甾醇的开发现状和发展趋势

介绍了甾醇的分布与种类,并从植物甾醇的角度论述了其功能与应用、来源、生产、开发利用现状和市场发展趋势。     

酶催化合成大豆甾醇油酸酯的工艺研究

以大豆甾醇和油酸为原料,在酶的催化下合成大豆甾醇油酸酯,采用高效液相色谱对产物进行定性定量分析,通过单因素实验考察催化剂脂肪酶的种类和用量、醇酸摩尔比、反应温度和反应时间等对大豆甾醇油酸酯产率的影响,并通过正交实验优化大豆甾醇油酸酯的合成工艺条件。采用红外光谱对产物进行了表征。结果表明:大豆甾醇油酸酯的最佳合成工艺条件为催化剂N435脂肪酶用量6%(以大豆甾醇和油酸的总质量计)、醇酸摩尔比1∶1、反应温度50℃、反应时间30 h、异辛烷用量10 mL(大豆甾醇为1 mmol时),在最佳条件下大豆甾醇油酸酯产率为86. 51%;红外表征说明合成的产物为大豆甾醇油酸酯。     

食品加工对植物甾醇的影响

血脂过高引起的心血管病已成为威胁人类健康的第一杀手，植物甾醇因其具有显著的降血脂作用而倍受关注。论述了植物甾醇的天然来源、存在形式及食品加工对其影响，以利于控制食品加工条件，最大限度地使甾醇得到保留。     

The detection of the presence of hazelnut oil in olive oil by free and esterified sterols

Genuine olive and hazelnut oils from diverse geographical origins, as single varieties and blends, were mixed at different percentages and analysed by the method based on the quantification of free and esterified sterols. Two formulas based on three sterols (Campesterol, Δ⁷-stigmastenol and Δ⁷-avenasterol) together with empirical decision rules were able to detect the presence of hazelnut oil in olive oil when the percentage of the former was more than 6–8%, although this figure was much lower in the most of the adulterations. Results of univariate and multivariate statistical procedures based on the analysis of 116 samples are presented in support of the method efficiency.     

大豆甾醇酯的物理性质及其对鱼油氧化稳定性的影响

旨在为大豆甾醇酯（SSEs）的合理高效利用提供理论依据,以大豆甾醇（SS）和脂肪酸为原料,采用酶法制备了大豆甾醇油酸酯（SSO）、大豆甾醇亚油酸酯（SSL）和大豆甾醇共轭亚油酸酯（SSC）,采用化学法制备了大豆甾醇棕榈酸酯（SSP）和大豆甾醇硬脂酸酯（SSS）,分析了5种SSEs的脂溶性、熔融结晶特性及热稳定性,并探究了不同添加量SSEs对鱼油氧化稳定性的影响。结果表明：SSO、SSL和SSC的脂溶性远高于SS,而SSP和SSS的脂溶性相较于SS并无明显改善;差示扫描量热与热重分析表明SS与不饱和脂肪酸的酯化反应比饱和脂肪酸能更有效地降低SS的熔点和结晶点,其热稳定性顺序为大豆甾醇饱和脂肪酸酯>大豆甾醇不饱和脂肪酸酯>SS。SSEs添加量为0.1%和1%时,5种SSEs对鱼油均具有较好的抗氧化性。综上,不饱和大豆甾醇酯相较于SS具有良好的脂溶性,在油脂的抗氧化方面具有良好的应用前景。     

植物甾醇提取新工艺

以甲酯化大豆油脱臭馏出物经离子交换吸附VE后得到富含甾醇的过柱液作为原料,以正己烷作为提取溶剂,采用冷却结晶的方法分离粗甾醇,再以丙酮作溶剂对粗甾醇进行重结晶.通过单因素和正交试验确定最佳结晶工艺条件:结晶时间18h,结晶温度2℃,料液比1/2(g/ml),在此条件下甾醇纯度为84.39%,用丙酮重结晶得到甾醇产品纯度为94.87%.     

植物甾醇研究与应用

植物甾醇具有诸多重要生理功能,对人体保健、卫生、美容能发挥很大有益作用,尤对甾体药物工业发展意义重大。该文主要对植物甾醇结构、分类、理化性质与生理作用、应用与开发进行综述,以期为今后甾醇应用与开发研究提供参考。     

木质素基水处理剂的合成及性能研究

以木质素磺酸钙为原料,经过羟基化改性、与亚磷酸反应、接枝季铵盐单体等一系列的反应,合成了多功能木质素水处理剂。采用红外光谱对原料木钙、合成产物进行了表征。通过脱色实验、静态挂片实验、静态阻垢实验对产物的絮凝性、缓蚀性、阻垢性进行了研究。结果表明,絮凝性、缓蚀性较好,阻垢性能较差．     

植物油中甾醇组成及总量测定方法的改进

在2个国际标准方法ISO 12228和COI/T.20/Doc.no.10的基础上,对植物油中甾醇组成及总量的检测方法进行了改进,并将改进方法与2个国际标准方法进行了比较.结果表明:在测定植物油中甾醇组成及总量时,选用5α-胆甾烷基-3β-醇作为内标,氧化铝柱提取不皂化物,99％双三甲基硅基三氟乙酰胺+1％三甲基氯硅烷和等体积的无水嘧啶作为衍生剂以及采用恒温气相检测条件不仅提高了检测速度,还降低了操作难度及操作成本.同时,使用改进后的方法对10个不同的植物油样进行了重复性验证,结果重复性均在国际标准方法要求范围之内.     

Screening for natural defence mechanisms of Lactococcus lactis strains isolated from traditional starter cultures

Three different bacterial defence mechanisms were identified in the seventeen Lactococcus lactis isolates from starter cultures in three Slovenian dairy plants. Isolates MB18, KR7, PT4, PT13 and PT19 inhibited phage adsorption by means of exopolysaccharides production. The most extensive polysaccharides production was detected in PT19 isolate, which was susceptible only to phage ΦPT19. Eight isolates exhibited nuclease activity, and seven of them were susceptible up to four phages out of thirteen from our collection. Eight isolates possessed the abiB gene, fourteen isolates abiH, two isolates abiJ and one isolate abiQ. Isolates PT27 and PT28 possessed AbiB, AbiH and AbiJ mechanisms as well as inhibition of phage adsorption. Isolate MB18, which was susceptible to one phage only, possessed the abiQ gene, nuclease activity and ability to prevent adsorption of most phages. Isolates PT67 and PT70, possessing only AbiH mechanism, were susceptible to only two phages.     

STEROL BIOSYNTHESIS BY STRAINS OF SACCHAROMYCES CEREVISIAE IN THE PRESENCE AND ABSENCE OF DISSOLVED OXYGEN

The content of sterols in Saccharomyces cerevisiae which has been harvested after anaerobic growth and then added to a complex nutrient medium, rises rapidly from ca. 1 mg/g dry yeast to ca. 10 mg in the presence of dissolved oxygen. A range of sterols, present principally as sterol esters, is formed during this period. The concentration of free sterols does not rise above 3 mg/g and esters are thought to form a reserve sterol pool. Cyclization of squalene to lanosterol in the presence of oxygen seems not to be markedly affected by oxygen concentration in contrast to demethylation and desaturation reactions on the pathway to ergosterol. When oxygen concentration falls to zero, further metabolism of preformed sterols continues, with the accumulation of episterol and ergosterol and reduction in the concentration of zymosterol and 24(28)-dehydroergosterol. During anaerobic growth a marked hydrolysis of sterol esters occurs and free sterols eventually predominate.     

甾醇酯微胶囊制备工艺研究

研究了喷雾干燥法制备微胶囊化甾醇酯的工艺。研究结果表明:微胶囊化甾醇酯的最优乳化条件为:复合乳化剂配比(单甘酯∶蔗糖酯)为1∶9;乳化剂用量0.75%;壁材用量20%;壁材比(变性淀粉∶麦芽糊精)为1∶5;芯材/壁材为0.5。喷雾干燥法制备甾醇酯微胶囊的最佳工艺参数为:进料温度50～60℃、均质压力50 MPa、进风温度180℃、出风温度80℃、喷雾压力180 KPa。在此工艺条件下微胶囊化效率可达77.8%。