关于油脂酸价测定中指示剂的选择

油脂酸价是油脂的一个重要理化常数,在通常测定酸价时,一般使用酚酞作为指示剂。但对于酸价高、颜色深的油脂,因用酚酞作为指示剂其终点不易判别,故选择了百里香酚酞和百里香酚蓝作为指示剂进行了一系列实验,其结果证明,对于低酸价、颜色浅的油脂,一般以酚酞作为指示剂较好,而酸价高、颜色深的油脂则以百里香酚蓝作为指示剂为好。     

油脂酸价和过氧化值检测方法的研究进展

食用油脂是人类膳食的重要组成部分,是人类机体所必需三大宏量营养素之一。油脂在运输和储存过程中,受热、光、空气中的氧气及油脂中水分和酶的作用,会发生各类化学变化而引起油脂品质的改变,即酸败。油脂的储存品质、质量指标和卫生指标对酸价和过氧化值的限值有明确的规定,酸价和过氧化值过高会对人体健康带来危害。因此油脂的酸价和过氧化值已成为该类产品品质监督和质量安全监管的重要技术参数。测定食品体系中油脂氧化程度时,需要对样品进行提取油脂的预处理以方便进行下一步检测。由于油脂在提取的过程中仍在发生持续的氧化反应,因此温度和时间、提取试剂种类和用量、浸提方式及溶剂挥发的方式等都会对检测结果有一定影响。本文主要对油脂酸价和过氧化值检测的检测方法进行了概述。     

食用油脂中p-茴香胺值的测定

对ISO中食用油脂的p-茴香胺值测定方法进行了验证,并对影响茴香胺值测定的影响因素进行了探讨。对几种食用油脂茴香胺值的测定结果进行统计分析表明,ISO法准确性、重复性好。在茴香胺值测定过程中应注意取样量、样品、试剂含水率等因素。另外,对于低含氧酸油脂,可以用正己烷代替ISO方法中的异辛烷试剂。     

食用油脂中3-MCPD脂肪酸酯和缩水甘油脂肪酸酯分析方法研究进展

随着对油脂中3–MCPD脂肪酸酯(ME)和缩水甘油脂肪酸酯(GE)研究和检测技术的不断更新,在精炼棕榈油中发现了ME存在,且在大多数食用油脂中发现了GE存在。ME和GE作为两类食用油脂加工过程中产生的污染物,对人体可能存在致癌性。目前对ME和GE的检测有直接方法和间接方法 2种,直接方法主要是对油样处理或不处理后直接用LC–MS、LC–MS/MS、LC–TOF–MS、GC–MS等进行检测;间接方法是将ME和GE醇解为3–MCPD和缩水甘油酯,苯硼酸或七氟丁酰咪唑衍生化后用GC–MS或GC–MS/MS检测。该文对现有的ME和GE检测方法的样品处理过程、仪器条件、结果等加以比较和分析探讨。     

我国油脂工业和油脂消费的变化

随着外资企业在我国新建大型现代化油脂加工厂,带动了我国油脂工业的革命,使建厂、管理、设计与制造理念、加工产能和油脂消费等方面看都产生了巨大的变化。受国际油料的产能及市场的影响,我国油料的种植面积已出现下滑,影响到了我国食用油消费的质量和安全,为应对当前油脂工业发展趋势,建议在我国政府在粮油安全和科研开发方面采取一系列的积极措施,以确保粮油食品的供给安全。     

动植物油脂不皂化物测定方法研究

通过对国内外动植物油脂不皂化物检测方法比较,考察不同检测方法对动植物油脂不皂化物测定结果影响,并分析造成结果差异原因。结果表明,美国油脂化学家学会(AOCS)两项方法AOCS Ca 6a-40(09)和AOCS Ca 6b-53(09)较IS03596:2000和IS018609:2000方法适用范围广,可实现对不皂化物含量较高动植物油脂检测,且萃取过程充分、技术路线严谨、测定结果准确可靠。     

Further studies and observations on 2-thiobarbituric acid assay (fat autoxidtion) and 2-thiobarbituric acid-aldehyde reactions

Studies both on the 2-thiobarbituric acid assay (fat autoxidation, fat rancidity) and 2-thiobarbituric acid-aldehyde reactions were carried out. Physico-chemical properties in solution of the reagents (2-thiobarbituric acid, malonaldehyde) and the red adduct, especially, were evaluated. The 2-thiobarbituric acid structure did not change if heated in diluted acid media (until 1% v/v concentration for strong acids) or in 50% v/v concentration for weak acids, as acetic acid. For high acid concentrations, especially with oxyacids (phosphoric acid, trichloroacetic acid), an oxidant hydrolytical effect can be observed. Diluted solutions of malonaldehyde, in a diluted weak acid medium, remained stable for more than ten days. For the first time the stoichiometries of the red and yellow adducts in solution were determined. Both the absorption maxima and molar absorptivity of the red adduct in acid medium were determined. The neutral and alkaline media were less favourable for the assay sensitivity and stability. The more suitable organic solvents for using in the optimized 2-thiobarbituric acid assay in aqueous medium were cyclohexane, chloroform and the ethers, because the red adduct was not very soluble (less than 0.1 g/1) in the organic solvents (fat extractors).     

自动电位滴定法测定油脂皂化值

采用电位滴定仪测定了油脂的皂化值,利用电位滴定仪能够识别多个滴定终点的特点,采用分步滴定法用盐酸分别滴定皂化液中过量的氢氧化钾和生成的钾皂,根据滴定钾皂消耗的盐酸的量可计算出样品的皂化值.分别采用全自动电位滴定法和国标GB/T 5534-2008规定的方法对3个不同菜籽油样品各平行测定6次,前者测定结果的相对标准偏差为0.16％～0.22％,优于国标方法测定结果的相对标准偏差0.36％～0.81％.     

Rapid determination of polar compounds in frying fats and oils using image analysis

Fats and oils were exposed to high temperature at 145°C for 80 h with frying steamed noodles, and the polar compounds were determined using a standard column chromatography and a novel image analysis method. The image was separated into polar and nonpolar component on TLC plate, and recorded with a camera. When the original image was transformed into 3 monochrome components of red, green and blue, respectively, pseudo-mass (the intensity-weighted area) ratio of image processed with a red-frame was highly correlated with real mass determined by column chromatography. The content of polar compounds for respective frying oils was calculated with the standard curves of first order regression that showed the determination coefficients of R²>0.8 (P<0.001). Consequently, it seemed that image analysis on polar compound could replace the extremely time and chemical consuming standard method for estimating the quality of frying fats and oils.     

The determination of erucic and cetoleic acids in oils, fats and fatty foods

A method for separating the methyl esters of erucic and cetoleic acids is described. Separation was achieved on silica gel plates impregnated with silver nitrate, utilising multiple development with a toluene: hexane mixture at a temperature of ?23°C. Mixtures of rapeseed and herring oil fatty acid methyl esters have been separated by the method described and quantified by gas chromatography.     

两种方法检测食用油脂中的多环芳烃

分别建立同位素内标定量-QuEChERS净化-气相色谱-三重四级杆串联质谱法(方法一)和GPC自动净化-高效液相色谱-荧光检测法(方法二)两种方法,为检测食用油脂中欧盟优先控制的16种多环芳烃(EU15+1PAHs)提供了快速有效的方法。分别对104份食用油脂样品进行分析比较,对比两方法检测结果。结果表明:两方法均满足国内外对食品中PAHs检测的要求,方法一、方法二精密度实验RSD值分别小于5.4%、6.81%,平均加标回收率除个别外,分别在71.3%~111.6%、93.1%~119%范围内,RSD值分别小于5.0%、5.5%;标准曲线线性方程相关系数分别大于0.998、0.990,方法一定量限范围为0.23~0.50μg/kg,方法二定量限为0.9μg/kg、检出限为0.3μg/kg;英国食品化学分析实验室能力验证(FAPAS)盲样测定结果均达到规定检测结果;两方法对104份油样的两组检测结果无统计学差异,整体分析和分不同油种比较结果基本一致。结论:建立了针对食用油中EU15+1PAHs的分析方法,两方法均满足相应检测要求,且具有良好的准确性和实用性。     

两种方法检测食用油脂中的多环芳烃

分别建立同位素内标定量-QuEChERS净化-气相色谱-三重四级杆串联质谱法（方法一）和GPC自动净化-高效液相色谱-荧光检测法（方法二）两种方法,为检测食用油脂中欧盟优先控制的16种多环芳烃（EU15+1PAHs）提供了快速有效的方法。分别对104份食用油脂样品进行分析比较,对比两方法检测结果。结果表明:两方法均满足国内外对食品中PAHs检测的要求,方法一、方法二精密度实验RSD值分别小于5.4%、6.81%,平均加标回收率除个别外,分别在71.3%¹11.6%、93.1%¹19%范围内,RSD值分别小于5.0%、5.5%;标准曲线线性方程相关系数分别大于0.998、0.990,方法一定量限范围为0.23⁰.50μg/kg,方法二定量限为0.9μg/kg、检出限为0.3μg/kg;英国食品化学分析实验室能力验证（FAPAS）盲样测定结果均达到规定检测结果;两方法对104份油样的两组检测结果无统计学差异,整体分析和分不同油种比较结果基本一致。结论:建立了针对食用油中EU15+1PAHs的分析方法,两方法均满足相应检测要求,且具有良好的准确性和实用性。      

2003年的中国油脂工业

2003年是中国油脂工业快速发展中的"黄金年".2003年中国油脂工业产销两旺,全年8种主要油料总产5 694.5 万t,折油965 万t,加之进口油料油脂折油922.8 万t,总计生产油脂1 887.8 万t,人均供给量达到14.5 kg,人均消费量达到11.5 kg.在对我国油脂工业现状进行分析的基础上,对我国油脂工业在高速发展中存在的问题进行了分析,强调要控制我国油料油脂进口总量,在目前情况下不能再盲目扩大油脂加工能力,并对我国油厂规模和布局进行了论证,对我国油脂消费市场进行了分析.     

Formaldehyde as an interference of the 2-thiobarbituric acid test

The 2-thiobarbituric acid (TBA) test is widely used for measuring rancidity in foods. It is based on the colorimetric determination of a pink chromogen which is formed by reaction between TBA and TBA reactive substances (TBARS). Besides malonaldehyde (MA) many other substances have been reported to react with TBA. The formation of formaldehyde (FA) from the trimethylamine oxide (TMAO) decomposition in sea fish has been extensively studied. Considering that FA reacts with the TBA forming a white precipitate or cloudiness the interference of FA with TBA test is studied concluding that FA contents over 25 μg ml^?1 extract interfere with the colorimetric determination during the storage of frozen blocks of Patagonian hake (Merluccius hubbsi) filleted and minced.     

高碘酸氧化法测定油脂中1-单甘酯的含量

对用高碘酸氧化法测定油脂中 1- 单甘酯含量的方法进行了研究,并对测定结果进行数理统计分析,重点讨论了影响 1- 单甘酯含量测定结果的一些因素.     

昆虫功能性油脂的研究

昆虫油脂及其他脂质是一类具有很多生理活性功能的油脂类物质 ,具有较高的研究及开发利用价值。本文讨论了昆虫脂质的开发现状与意义 ,综述了昆虫油脂的研究进展。     

油脂的营养与健康

油脂的营养与健康是当今消费者普遍关注的问题之一,也是国际学术界有关领域的研究热点之一。天然油脂是甘油三酯的混合物并且含有其他少量成分。天然甘油三酯的营养与健康主要涉及到两个方面的问题：单个脂肪酸的营养与健康;不同脂肪酸平衡摄入比的营养与健康。前者有大量的研究数据和丰富的试验数据,可对消费者提供有价值的指导作用;后者有关脂肪摄入量和脂肪酸摄入平衡问题,推荐值不尽一致并且还受一些因素（如富裕程度、地方文化传统及饮食习惯等）的影响。     

食用油脂中碘值快速检测试剂盒的研制及其性能评价

对食用油脂中碘值的快速检测方法进行研究,研制出相应的快速检测试剂盒并对其性能进行测试。试验表明快速检测试剂盒相比于国标法方法更加方便快捷而且准确度高,检测时间由1 h以上缩短至10 mins,在常温条件下存放6个月时间内其稳定性良好对碘值的测试结果与国标方法基本一致。该试剂盒的研制弥补了国内相关产品的空白,符合未来食品快速检测技术的发展趋势。     

生物技术在油脂工业中的应用

概述了生物技术在油脂工业中的应用,指出应用生物技术所带来的相应问题,并展望其应用前景。     

Interference by formaldehyde in the 2-thiobarbituric acid test for rancidity

The 2-thiobarbituric acid (TBA) test is often used to detect oxidative rancidity, although certain limitations of the technique have been described. This study was of formaldehyde (FA) interference in the TBA test in model systems involving various concentrations of malonaldehyde (MA), FA and TBA. At a TBA concentration of 20 μmol ml^?1 it was found that FA could give rise to turbidity or precipitation. However, as the amount of MA in the reaction mixture increased (10 to 400 times higher than the upper limit of the standard curve), higher FA concentrations were required. Turbidity or precipitation resulted in fluctuating readings, and centrifugation or filtration lowered the readings (532 nm) to below those obtained when no FA was present. The ratio of TBA to MA must be ?1000 for full colour development, and hence lack of colour may be due to the TBA acting as a limiting factor in the reaction. The presence of a peak at 323 nm and/or turbidity or precipitate confirmed of the reaction between FA and TBA. FA competed with MA for TBA thereby lowering the effective TBA:MA ratio. Other TBA-reacting substances (TBARS) present in the medium may augment this effect.