油脂的自动氧化和氧化稳定性及检测方法

论述了油脂自动氧化的机理和油脂氧化稳定性的测定原理，并对油脂氧化稳定性的测定方法作了简要介绍。     

油脂的自动氧和氧化稳定性及检测方法

论述了油脂自动氧化的机理和油脂氧化稳定性的测定原理，并对油脂氧化稳定性的测定方法作了简要介绍。     

油脂氧化及其氧化稳定性测定方法

论述了油脂氧化的机理和油脂氧化稳定性的测定原理,按测定参数的不同对油脂氧化稳定性的常用测定方法进行了分类和介绍,旨在为选用合理的油脂氧化稳定性测定方法和今后开发更新的测定方法提供参考。     

油脂的氧化稳定性测试

油脂在贮存过程中会由于发生氧化反应和水解反应最终导致酸败。测定油脂酸败程度的方法多种多样,但最有指导意义的是对油脂氧化反应过程中诱导期的测定。采用氧化稳定性测则试了多种常用油脂的氧化稳定性,模拟了油脂氧化初期的过程,对预测油脂的货架寿命有一定指导意义。     

热重分析法在油脂氧化稳定性研究中的应用

主要介绍了热重分析法在食用油脂氧化稳定性定性分析中的应用,检测了菜籽油、玉米油、调和油3种油脂的氧化分解温度,探讨了升温速率、保护气氛对油脂氧化分解温度的影响;通过油脂的热重分析法等温实验,观察了油脂的氧化诱导时间。实验表明:菜籽油的氧化稳定性优于玉米油和调和油;相同条件下,升温速率越快,氧化分解温度越高;在氮气气氛下,油脂的氧化稳定性更好。热重分析方法采样量少、操作方便、效果明显,可以应用于油脂生产过程的质量监控和抗氧化剂的开发研究。     

提取方法对3种坚果油脂理化性质及氧化稳定性的影响

研究了溶剂法和水酶法提取核桃、扁桃、大扁杏仁等3种坚果油脂的理化性质,气相色谱法分析了坚果油脂的脂肪酸组成,比较了加速氧化过程中3种坚果油脂酸价及过氧化值的变化,采用Rancimat油脂氧化仪测定了不同方法得到油脂的氧化稳定性。结果发现,油脂制备方法对其理化特性和氧化稳定性均有重要影响,其中,3种水酶法提取油脂的透明度、酸价和风味均优于溶剂法,而氧化稳定性均低于溶剂法,但是不同方法提取油脂的折光指数、碘价、皂化价和不皂化物以及脂肪酸组成等理化特性不存在显著差异。在加速氧化实验中,油脂酸价变化不大,而过氧化值和OSI变化较大。3种坚果油脂中,大扁杏仁油最为稳定、扁桃油次之,而核桃油最容易氧化。     

微胶囊多不饱和脂肪酸粉末的氧化稳定性研究

油脂氧化是油脂工业中控制产品质量所面临的一个很重要的问题,如何检测油脂产品的氧化稳定性并准确预测其保质期是油脂行业和添加剂等食品行业所面临的关键技术问题。最简单的加速测试利用烘箱储存法,目前Schaal烘箱法是油脂和食品行业中经常用来评估油脂和烘焙食品氧化稳定性的方法。随着人们对多不饱和脂肪酸生理功效的逐步认知,市场对该类产品的需求亦急速增加。本研究利用Schaal烘箱法对几种现有的微胶囊多不饱和脂肪酸粉末进行了氧化稳定性检测和保质期的预测。     

微波处理油料对油脂品质影响的研究进展

介绍分析了微波处理油料对出油率、原料本身结构、油脂主要理化指标、油脂脂肪酸组成及微量成分和油脂氧化稳定性的影响.结果指出微波处理油料可提高出油率和油脂氧化稳定性,增加营养成分含量,值得推广应用.     

不同大豆品种提取油脂氧化稳定性研究

该实验采用自动索氏抽提仪对不同大豆品种提取油脂,气相色谱分析其脂肪酸组成,酸败仪测其氧化稳定性方法,研究不同大豆品种提取油脂脂肪酸组成与其氧化稳定性之间关系。实验发现,一般而言,油酸、亚油酸含量较高大豆品种油脂氧化稳定性相对较好,亚麻酸含量较高品种油脂氧化稳定性较差;但有些大豆品种,如:栽培种169号,野生种y112号大豆脂肪酸组成,其亚麻酸含量较高,分别为10.89%、13.45%,测得诱导时间却较长,分别为8.15h、8.25h;分析原因,发现其中含有天然抗氧化成分,可阻止或延缓油脂氧化。     

磷脂与游离脂肪酸对油脂烟点和氧化稳定性的影响

考察了磷脂含量、游离脂肪酸含量、游离脂肪酸碳原子数和不饱和度对花生油和山茶油烟点和氧化稳定性的影响。结果表明:磷脂含量对油脂烟点影响很大,含量越高,烟点越低,对油脂氧化稳定性表现出不同规律,其对花生油氧化稳定性有一定的提高作用,而对山茶油则影响不大;游离脂肪酸含量越高、游离脂肪酸碳原子数越少和不饱和度越大,油脂的烟点越低、氧化稳定性越差,并且相对于氧化稳定性,对烟点的影响要大得多。     

Physical and Chemical Properties of Randomly Interesterified Blends of Corn Oil and Tallow

The sodium methylate-catalyzed random interesterification of corn oil-tallow blends was explored in order to develop plastic fats of varying physical properties. Lipase hydrolysis of the randomized fats showed that with 0.5% catalyst, interesterification was completed within 30 min at 80°C. Interesterification decreased the melting point and solid fat index of the randomized fats. The trans- fatty acid level and fatty acid profile of the rearranged fats did not show any change upon interesterification. The oxidative stability of the fats decreased after random interesterification, but addition of 0.01% citric acid and 0.01% butylated hydroxyanisole produced a fat blend of comparable stability to commercial margarine oils.     

Simple enrichment procedure for the estimation of minor polyunsaturated fatty acids in food fats

A simple, reliable and sensitive method, involving the partition of a mixture of fatty acid methyl esters (FAME) between hydrocarbon solvent and aqueous ethanolic silver nitrate, is described for the estimation of low concentrations of polyunsaturated fatty acids (PUFA) in fats and oils. It is suggested that this procedure could be used to give an indication of oxidative stability of food fats and of their potential for off-flavour development.     

High resolution 1H nuclear magnetic resonance in the study of edible oils and fats

In this paper a review of the applications of high resolution ¹H NMR to the study of edible oils and fats is reported. Aspects such as sample preparation and acquisition parameters are treated. The assignment of the ¹H NMR signals of the major and minor components of unoxidized and of thermally stressed edible oils and fats is given. The usefulness of this technique in the determination of degree of unsaturation and of the proportion of the different acyl groups, is examined. In addition, the capability of this technique to assess the quality and genuineness of olive oil and to detect adulterations is discussed. Finally, its contribution in the study of the oxidation of edible oils and fats and its effectiveness to determine not only primary but also secondary oxidation products, and also oxidative stability is shown.     

油脂的风味及感知

油脂是一种重要的营养物质。随着我国经济水平的发展,居民越来越多地关注油脂的风味品质。油脂原料本身的差异以及加工制备过程中的脂肪氧化降解、热分解、美拉德反应等是影响油脂形成不同风味品质的主要因素。口腔加工中油脂及其制品经过味觉、嗅觉、三叉神经感觉等方面相互作用,在大脑特定区域形成风味的认知。目前有研究证明脂肪酸转位酶（CD36）、G蛋白偶联受体（GPCR）等受体参与到一个专门用于感知脂质的感官系统。因此,有人提出脂肪可能是第6种味道。复杂的多感官交互依赖于人类所有感官的反应,未来关于脂肪感知以及脂肪参与多感官交互方面还需要进一步研究。     

食用油脂中合成抗氧化剂的检测分析研究进展

向油脂中添加合成抗氧化剂是防止食用油脂在使用过程中发生氧化酸败的最有效方法之一,国家规定油脂中合成抗氧化剂添加的最大限量标准为200 mg/kg,因此建立准确、快速和高效的分析方法检测食用油脂中合成抗氧化剂的含量保证油脂以及含油食品的质量安全具有十分重要的意义。食用油脂中抗氧化剂的检测方法较多,最常用的有高效液相色谱法、气相色谱法、高效液相色谱-串联质谱法、气相色谱-串联质谱法等。本文主要综述了近年来食用油脂中合成抗氧化剂检测分析方法的研究进展,总结了不同分析方法之间的差异,并对今后的发展趋势加以展望。     

Tween对精炼大豆油氧化稳定性的影

本文采用烘箱法和Rancimat法研究了亲水性乳化剂Tween（如Tween20、Tween60和Tween80）对精炼大豆油氧化稳定性的影响。低温下的烘箱法研究结果表明：对于Tween20,添加0．005％时可以延缓油脂的氧化．添加量增加到0．01％～0．20％时会在一定程度上起到促进氧化的作用;添加Tween60会在一定程度上起到促进氧化的作用：添加Tween80能延缓油脂的氧化,添加量为0．005％时效果最明显。高温下的Rancimat法结果表明：添加0．005％的Tween20具有一定的抗氧化作用,加入0．01％邗．20％Tween20对油脂的氧化稳定性影响不明显。添加Tween60对大豆油的氧化稳定性没有太大影响。添加Tween80能延缓油脂的氧化,加入0．005％Tween80时延缓氧化的效果最好。     

Conjugated Linoleic Acid (CLA) Formation in Edible Oils by Photoisomerization: A Review

Conjugated linoleic acid (CLA) that is commonly found in dairy and ruminant fats, is geometrical and positional isomer of linoleic acid (LA). Edible oils are not good sources of CLA. Attempts have been made to generate CLA in edible oils through photoisomerization procedures. CLA isomers have several proven health benefits. This article reviews procedures for producing CLA containing edible oils by photoisomerization approach and applications of photoisomerized oils for food uses. The article reviews (1) the photoisomerized production of CLA containing oils on lab scale, with customized equipment, at pilot plant scale; (2) the effects of iodine content, photoisomerization time, refining, interference from minor components of oils, efficacy of different edible oils containing LA, interference from antioxidants; (3) the chemical kinetics, oxidative stability; and (4) photoisomerized oils for frying oils and as drying oils.The review also briefly covers methods of measurement of CLA.     

鼠尾草酸抑制油酸甲酯热氧化反应作用研究

食用油热加工过程中油脂氧化劣变 对人体健康存在风险,有效控制油脂氧化劣变,对提升食品安全水平具有重要意义。针对鼠尾草酸（Carnosic acid,CA）如何有效抑制油酸甲酯热氧化反应这一科学问题,利用国标法、液相色谱（High Performance Liquid Chromato- graphy ,HPLC）、电子顺磁共振（Electron Spin Resonance,ESR）分析CA对油酸甲酯热氧化反应的抑制作用。结果表明,加入抗氧化剂能够显著降低油酸甲酯主要特性指标游离脂肪酸（Free fatty acids ,FFA）、酸价（Acid value,AV）、过氧化值（Peroxide value ,POV）、p-茴香胺值（p-anisidine value ,PAV）、总氧化值（Total oxidation value ,TOTOX值）和抑制主要醛类羰基化合物和自由基的产生。其中CA对油酸甲酯FFA、AV和自由基的抑制作用效果略好于TBHQ,而在POV、PAV、TOTOX和醛类羰基化合物方面稍逊于TBHQ。电子顺磁共振分析表明CA比TBHQ对油酸甲酯中自由基含量的抑制效果更为明显。研究表明加入抗氧化剂可以提高油酸甲酯的热氧化稳定性,其作用效果可与TBHQ媲美。     

Oxidative stabilities of mango kernel fat fractions produced by three-stage fractionation

Trans-free mango kernel fat stearins and oleins were produced by three-stage acetone fractionation to achieve the sufficient utilization of fat. Fatty acid and triacylglycerol compositions, slip melting points, iodine values, micronutrient (tocopherol, sterol, and squalene) levels, as well as oxidative stability indexes of the fractions were analyzed to evaluate their qualities. The most abundant fatty acids in the stearins were saturated fatty acids (57.3–65.1%, mainly including palmitic, stearic, and arachidic acids), and the major triacylglycerols were symmetrical monounsaturated types (78.3–93.7%). The unique properties make the stearins show highest slip melting points 34.7–38.3°C and oxidative stability indexes (12.0–14.2 h), and very suitable for the manufacturing of hard chocolate fats. The oleins contained high percentages of monounsaturated (48.3–53.7%) and polyunsaturated fatty acids (7.8–8.5%). Their oxidative stability indexes (6.3–6.7 h) were lower than the stearins but higher than common commercial oils. About 85.2% of tocopherol, 99.2% of sterol, and 79.2% of squalene were transferred to the liquids after fractionation, which could improve their antioxidant abilities. Further multiple linear regression analyses between oxidative stability indexes and fat compositions revealed that polyunsaturated fatty acid and sterol were the main factors that affect the oxidative stabilities of the fractions. The results suggested that the moderated refining techniques should be developed to retain more sterol to improve the oxidative stabilities and nutritive values of the fats.     

油脂加工厂臭味气体处理实践

油脂加工厂臭味气体包括油脂氧化生成小分子物质及豆腥味气体,浸出车间因正己烷、油脂和豆粕在生产过程中产生各种气味,精炼和污水处理中的油脂和化学剂等接触氧化产生臭味气体,小品种油料浓香油机榨车间产生的油味等。阐述几种脱除臭味气体技术,对芝麻油机榨车间的臭味气体采用3级静电场+氧聚解,压榨和精炼车间采用微波等离子光氧催化恶臭气体净化,对预处理、浸出和精炼车间产生的臭味气体采用脱臭液喷淋洗涤+复合光催化+VP布气脱臭。3级静电场+氧聚解的臭味气体脱除率达83%,脱臭液喷淋洗涤+复合光催化+VP布气技术的臭味气体排放指标达到国家相关标准。