A study on monitoring of frying performance and oxidative stability of cottonseed and palm oil blends in comparison with original oils

Blending polyunsaturated oils with highly saturated or monounsaturated oils has been studied extensively; however, in literature there is negligible information available on the blending of refined cottonseed oil with palm olein oil. Blending could enhance the stability and quality of cottonseed oil during the frying process. In the present study, the effects of frying conditions on physicochemical properties of the palm olein-cottonseed oil blends (1:0, 3:2, 1:1, 2:3, and 0:1, w/w) were determined and compared to the pure oils. The frying process of frozen French fries was performed in duplicate at 170 ± 5°C for 10 h without interruption. The oil degradations were characterized during deep-frying applications; peroxide, free fatty acid, and iodine value by standardized methods, fatty acid profile by using a gas chromatography-flame ionization detector, polar and polymeric compounds by using the high-performance size exclusion chromatography/evaporative light scattering detector technique. The present study clearly indicated that the oxidative and frying performances of pure palm olein oil and cottonseed oil significantly improved by blending application. Results clearly indicated that the frying performance of cottonseed oil significantly improved by the blending with palm olein oil. Except that free fatty acid content, all the physicochemical variables were significantly influenced by type of pure and blend oils. By increasing the proportion of palm olein oil in cottonseed oil, the levels of polyunsaturated fatty acids decreased, while saturated fatty acid content increased. The progression of oxidation was basically followed by detecting polar and polymeric compounds. The fastest increments for polar and polymeric compounds were found as 6.30% level in pure cottonseed oil and as 7.07% level in 40% cottonseed oil:60% palm olein oil blend. The least increments were detected as 5.40% level in 40% cottonseed oil:60% palm olein oil blend and 2.27% level in 50% cottonseed oil:50% palm olein oil blend. These levels were considerably below the acceptable levels recommended by the official codex. Therefore, the present study suggested that blending of cottonseed oil with palm olein oil provided the oil blends (50% cottonseed oil:50% palm olein oil and 40% cottonseed oil:60% palm olein oil, w/w) with more desirable properties for human nutrition.     

基于特征脂肪酸的食用油中棉籽油掺假鉴别技术

目的 开发检测棉籽油特征标志物锦葵酸和苹婆酸的气相色谱-质谱法,实现食用油中棉籽油掺假确证性鉴别。方法 利用碱式甲酯化方法对油脂样品进行酯化,正己烷提取脂肪酸甲酯,加入无水硫酸钠过滤,选择性离子扫描模式采集数据,外标法定量,以特征标志物判定食用油中是否掺假棉籽油。结果 建立的食用油中锦葵酸和苹婆酸高灵敏检测技术能准确鉴定食用油中5%棉籽油掺假。与基于脂肪酸组成结合偏最小二乘法-判别分析仅能鉴别大豆油中10%以上的棉籽油掺假相比,本研究建立的基于标志物方法鉴别灵敏度更高。结论 本研究建立了食用油中苹婆酸和锦葵酸高灵敏检测技术,为鉴别食用油中棉籽油掺假提供了关键检测技术支撑。     

Treatments of phospholipids to prevent or decrease colour fixation in cottonseed oil

To prevent or decrease colour fixation in cottonseed oil containing high level of phospholipids (4%), it was treated before or after fixation with chemical and physical treatments using ethanolamine, degumming or sodium silicate. Treatment of cottonseed oil with ethanolamine at 4% of the oil before or after fixation results in refined and bleached oils darker than the untreated oil. Carrying out degumming before fixation followed with ethanolamine at 1% only of the oil improved the oil colour. Treatment of cottonseed oil with sodium silicate at 1% of the oil before fixation results in superior refined and bleached oils than the untreated oils.     

Determination of trace nickel in hydrogenated cottonseed oil by electrothermal atomic absorption spectrometry after microwave-assisted digestion

Microwave digestion of hydrogenated cottonseed oil prior to trace nickel determination by electrothermal atomic absorption spectrometry (ETAAS) is proposed here for the first time. Currently, the methods outlined in U.S. Pharmacopeia 28 (USP28) or British Pharmacopeia (BP2003) are recommended as the official methods for analyzing nickel in hydrogenated cottonseed oil. With these methods the samples may be pre-treated by a silica or a platinum crucible. However, the samples were easily tarnished during sample pretreatment when using a silica crucible. In contrast, when using a platinum crucible, hydrogenated cottonseed oil acting as a reducing material may react with the platinum and destroy the crucible. The proposed microwave-assisted digestion avoided tarnishing of sample in the process of sample pretreatment and also reduced the cycle of analysis. The programs of microwave digestion and the parameters of ETAAS were optimized. The accuracy of the proposed method was investigated by analyzing real samples. The results were compared with the ones by pressurized-PTFE-bomb acid digestion and ones obtained by the U.S. Pharmacopeia 28 (USP28) method. The new method involves a relatively rapid matrix destruction technique compared with other present methods for the quantification of metals in oil.     

棉籽油物理精炼实践

一般认为棉籽油不宜进行物理精炼的主要原因是其中含有棉酚,但只要工艺方案选择合理,采用合理的工艺条件,是完全可以对棉籽油进行物理精炼的。提出了针对棉籽油进行物理精炼的切实可行的工艺方案和要求,并在实际生产中加以应用,取得了良好的工艺效果和经济效益。棉籽油进行物理精炼时,应使用较低的温度,较高的真空度,将酸值降至2 mgKOH/g左右时改用碱炼脱酸,既可提高精炼率,又可脱除油中的棉酚。     

棉籽油生产过程中棉酚的影响与对策

介绍了棉籽中棉酚的存在与性质,以及棉酚在棉籽油生产过程中可能发生的变化及影响。在毛油制取过程中采用润湿蒸炒,加稀碱液蒸炒,湿式膨化等预处理工序都可有效降低毛油中棉酚含量并提高粕的品质。碱炼是公认的脱除棉酚最有效的方法,但炼耗较高。在脱除棉酚和磷脂后棉籽油也可以进行物理精炼,并可获得良好的工艺效果。提出了在棉籽油中加入适量的邻氨基苯甲酸,再结合其他工序脱除棉酚的方法。     

两种溶剂萃取棉籽油和棉籽粕的质量比较

利用正己烷和异丙醇作溶剂,分别萃取棉籽仁得到棉籽油和棉籽粕.对棉籽油的理化指标进行测定,结果表明两种不同溶剂萃取得到的棉籽油在理化指标上存在一定的差异.分析所得棉籽粕的蛋白含量和功能特性,结果表明正己烷萃取的棉籽粕中粗蛋白含量和水溶性蛋白含量均低于异丙醇萃取的棉籽粕;正己烷萃取的棉籽粕吸油性、泡沫稳定性小于异丙醇萃取的棉籽粕,但是吸水性、乳化性、乳化稳定性和起泡性却高于异丙醇萃取的棉籽粕.分析游离棉酚含量时,发现异丙醇萃取的棉籽油中游离棉酚(FGP)含量高于正己烷萃取的棉籽油.用异丙醇萃取的棉籽粕中FGP含量在国家标准规定的安全使用限量范围内,用作饲料时不需再增加脱毒工艺.     

棉籽油脂肪酸甲酯化的方法及其脂肪酸含量分析

以新陆早39号以及新陆早50号的棉籽为材料,利用索氏提取仪提取其总油脂,分别采用三种常用的脂肪酸甲酯化方法:KOH-甲醇法,H₂SO₄-甲醇,14% BF₃-甲醇法进行甲酯化后,GC-MS上机分析;通过37种脂肪酸甲酯混标制定标准曲线,用外标法进行定量。结果表明:KOH-甲醇法甲酯化的脂肪酸GC-MS上机分析能检测到10种脂肪酸组分;H₂SO₄-甲醇与14% BF₃-甲醇法只能检测到6种。用KOH-甲醇法甲酯化后GC-MS测定表明,棉籽油脂肪酸以多不饱和脂肪酸的亚油酸为主,其次是饱和脂肪酸的棕榈酸以及单不饱和脂肪酸的油酸。在新陆早39号以及新陆早50号中,每克棉籽中亚油酸的含量分别达147.29 mg与163.2 mg,分别占其油脂含量的60.12%与60.83%;棕榈酸含量分别为65.05 mg与62.28 mg,分别占其油脂含量的26.55%与23.24%。油酸含量分别为24.79 mg与22.19 mg,分别占其油脂含量的10.12%和8.28%。结论:三种常用的脂肪酸甲酯化方法中,KOH-甲醇法更方便,快速,检测种类多,适用于棉籽脂肪酸的甲酯化。     

国家标准《棉籽油》的主要技术内容与编制说明

《棉籽油》国家标准的制定对规范我国棉籽油产业秩序,推动我国棉籽油产业健康稳定发展将起到积极的推动作用。介绍了《棉籽油》国家标准的编制原则和依据,对标准中棉籽油的术语和定义、分类、质量要求、检验方法及规则、标签、包装、储存和运输等内容的编制依据进行了说明。     

氢化棉籽油等温结晶动力学的研究

用脉冲核磁共振(PNMR)法测定了两种氢化条件下氢化棉籽油的固体脂肪含量(SFC)。根据不同温度下固体脂肪含量随时间的变化绘制等温结晶曲线。等温结晶曲线有两种:双曲线和反曲线。当过冷却度高时,结晶曲线为双曲线;当过冷却度低时,结晶曲线为反曲线。用Avrami方程进行氢化棉籽油的等温结晶动力学分析,结果表明:过冷却度与晶体的成核和生长方式有显著相关性。当过冷却度高时,结晶常数较小,晶体成核和生长速率快;当过冷却度低时,结晶常数较大,晶体成核和生长速率慢。研究氢化棉籽油的结晶行为对人造奶油、起酥油和可可脂替代品基料油的选择有一定的指导意义。     

棉籽油皂脚的开发与利用

随着近年来棉籽加工量的不断增加,棉籽油已跻身于大宗油料的行列中,尤其在新疆地区棉籽的加工量在国内名列前茅.因此,棉籽油皂脚的数量也十分可观,在新疆已成为一个亟待解决的问题.对棉籽油生产中下脚料--皂脚的综合开发利用途径进行了阐述,主要对皂脚特性以及皂脚生产磷脂、生物柴油、脂肪酸等方面的现状及生产技术方法进行了分析.结果表明,发展棉籽油皂脚的综合利用大有可为.     

棉籽油催化裂化制取轻质燃料油的研究

以棉籽油为原料，采用催化裂化工艺制取轻质燃料油，考察了反应温度、剂油比、反应时间对棉籽油催化裂化制取轻质燃料油的影响。以燃料油产率最大值为目标函数，利用响应面法优化操作变量，并建立了棉籽油催化裂化制取燃料油的数学模型，其计算结果与试验数据吻合良好；试验结果表明适宜的反应条件为：反应温度426℃，反应时间50S，剂油比7．8：1（m／m）；在此条件下有机馏分（≤〈360℃）产率65．6％，汽油馏分（≤205℃）产率33．7％，气体产率11．6％；制备的燃料油馏分可以作为石化汽油、柴油的调和组分。     

脱臭工艺条件对棉籽油中反式脂肪酸含量的影响

研究了脱臭温度和脱臭时间对棉籽油中反式脂肪酸含量的影响。结果表明:脱臭温度和脱臭时间对棉籽油中反式油酸含量的影响很小;脱臭温度对棉籽油中反式亚油酸含量影响显著,脱臭时间对其影响的显著性次之;在一定的脱臭时间,不同脱臭温度下,棉籽油中总反式脂肪酸最多含量为最少含量的100倍以上;在一定的脱臭温度,不同脱臭时间下,棉籽油中总反式脂肪酸最多含量约为最少含量的1.7～5.5倍,且在255℃以下随脱臭时间延长,棉籽油中总反式脂肪酸的形成速度缓慢、相对含量低。     

花生油中掺杂棉籽油、大豆油的鉴定方法概述

花生油中掺杂棉籽油、大豆油的现象比较普遍。主要以掺入这两种油的花生油为样品,通过伯利哀试验和气润色谱法测定不同掺入量的混浊温度和脂肪酸组成,从而对花生油的掺杂进行鉴定。     

棉籽油改性制备高档皮革加脂剂的研究

以棉籽油为主要原料,系统研究了酯交换引入羟基,以适度降低产物的分子量和黏度,采用顺丁烯二酸酐酯化经过改性的油脂,以增加产物与皮胶原结合的活性点。同时,探讨了氧化亚硫酸化的条件及对产品加脂性能的影响;将产品与其他材料配伍复配,以制备复合型皮革加脂剂。最后,通过皮革的加脂应用试验,确定了最佳的配方与工艺条件。     

两种精炼工艺在新疆棉籽油生产加工中的应用对比

阐述了两种精炼工艺(常规精炼工艺和混合油精炼工艺)的工艺流程及控制要点,并将两种工艺生产的成品棉籽油的各项指标进行对比分析。与常规精炼工艺相比,混合油精炼得到的成品棉籽油色泽R值低1.5~2.5,酸值(KOH)低0.08 mg/g,含皂量低0.015个百分点,皂脚含油低10~20个百分点,精炼得率提高2~6个百分点。混合油精炼工艺在新疆棉籽油生产加工中的应用具有精炼得率高、成品油色泽浅、动力消耗低、维护费用低等优势,解决了新疆棉籽高棉酚含量对棉籽油生产加工的不利影响,更适合于新疆棉籽油的加工。     

Effect of water and bht on stability of cottonseed oil during frying

The behaviour was studied in cottonseed oil which had been exposed to frying under controlled conditions in a system in which only the oil, water and/or the antioxidant BHT were present. In the oils, changes which had been caused by heating were evaluated through determination of acid, hydroxyl, TBA and iodine values, extinctions at 232 nm and 460 nm, fatty acid composition, viscosity, amounts of “polymers” and non-urea-adduct-forming fatty acid methyl esters. All the changes were less pronounced when the frying was carried out in presence of either nitrogen or water. The latter protected the oil only if it was present in amounts sufficient to generate such a volume of vapours which could effectively act as an inert gas-blanket. BHT had no delaying effect on the deterioration of the oil during frying. When the oil was heated in the presence of air, the antioxidant's destruction was lessened by the presence of water in the system, but a large portion of BHT was lost through steam distillation.     

A chemometric approach for the quantification of free fatty acids in cottonseed oil by Fourier transform infrared spectroscopy

The aim of this study was to quantify free fatty acid in cottonseed oil (Gossypium) variety by a chemometric approach using Fourier transform infrared spectroscopy. Calibration standards were prepared by gravimetrical mixing of oleic acid (0.1–40 g/100 g) in neutralized cottonseed oil containing <0.1% free fatty acids. Fourier transform infrared technique coupled with partial least square and principle component regression models were used to develop calibrations in the specific absorption region of carbonyl between 1690–1727 cm^?1. On the basis of regression coefficient and evaluated free fatty acids results with comparison to titration method, partial least square was found to be more accurate than principle component regression calibration model. All the analyzed cottonseed oil varieties showed high content of free fatty acids in the range of 17.1–38.5%. The results of the present study indicated that Fourier transform infrared method in combination with partial least square or principle component regression could be used as a greener alternative to the standard titration method.     

Bench-scale treatments of colour-fixed cottonseed oil

Bench-scale refining of crude colour-fixed cottonseed oil was carried out using equipment and conditions similar to those at a local factory. Ethanolamine at 2–3% level resulted in 55–62% reduction in the oil colour, and 24–26% reduction in the refining loss over the factory treated oil. Sodium silicate at 0.14–0.47% level resulted in about 50% reduction in oil colour and 24–44% reduction in the refining loss. A two-step treatment, first with caustic soda lye then with either additives, and miscella refining using ethanolamine as an additive, resulted in superior oil colour, yet the refining losses were high.     

棉籽蛋白资源开发研究进展

我国棉花资源丰富,棉花加工的副产物——棉籽经脱壳提油后的棉籽粕中蛋白质含量高达40%~50%。棉籽蛋白是一种营养价值高、品质良好的植物蛋白资源。介绍了棉籽蛋白的营养价值以及脱酚棉籽蛋白粉、棉籽浓缩蛋白、棉籽分离蛋白等产品的制备工艺及产品的溶解性、持水性、持油性、乳化性与乳化稳定性、起泡性与泡沫稳定性等功能特性的研究进展,并对棉籽蛋白产品目前在食品、饲料、发酵等领域的应用情况进行了论述。