不同食用植物油中维生素E组分及含量研究

通过对9个不同品种的138个食用植物油样品中维生素E组分及含量的测定,分析研究不同食用植物油中维生素E组分及含量的分布情况。结果表明:9个油脂品种、101个一级油样品中维生素E含量范围为5.9~1 246.6 mg/kg,平均值652.4 mg/kg,维生素E总量的平均值排序为大豆油棉籽油玉米油葵花籽油菜籽油米糠油花生油芝麻油山茶油;不同油脂样品中维生素E的组分有明显差别,米糠油含有最齐全的8种维生素E组分,并且生育三烯酚含量的平均值占维生素E总量平均值的44.2%;玉米油含有3种生育酚和2种生育三烯酚,棉籽油中含有3种生育酚和1种生育三烯酚,但这两种油脂中生育三烯酚含量平均值分别仅占维生素E总量平均值的5.8%和2.8%;大豆油、菜籽油、花生油、葵花籽油均含有α-、γ-、δ-生育酚3种组分;山茶油中含有α-、γ-生育酚2种组分;芝麻油仅含有γ-生育酚1种组分。除芝麻油之外,所有油脂中均含有α-生育酚和γ-生育酚,其中葵花籽油中α-生育酚含量最高,大豆油中γ-生育酚含量最高。同一油脂品种、不同等级的油脂中维生素E含量也存在差异,总体趋势是维生素E含量随油脂精炼程度的加深而降低,但个别二级菜籽油样品中维生素E含量低于一级菜籽油,这与所采集油脂样品的来源不同有关。不同油脂品种、不同等级的食用植物油中维生素E组分及含量因油料品种、油脂精炼工艺的不同显示出明显差异。     

HPLC法同时测定植物油中维生素A和不同构型维生素E含量

以石油醚为溶剂,用索氏提取法提取了黑芝麻、白花生、黑花生、葵花籽、大豆、棉花籽的油脂。油样品先用正己烷溶解,然后用甲醇定容,其中正己烷含量为20%(v/v),用Hypersil ODS2 5μm色谱柱,甲醇为流动相,对所提油脂中维生素A、α-维生素E、γ-(β)维生素E、δ-维生素E含量进行检测。实验结果表明,在204nm波长下,维生素A、α-维生素E、γ-(β)维生素E、δ-维生素E在0~200μg/m L范围内与峰面积有良好的线性关系,标准曲线相关系数r均大于0.9978。维生素A、α-维生素E、γ-(β)维生素E、δ-维生素E加标平均回收率分别为97.83%、98.58%、98.75%、99.93%。     

HPLC法同时测定植物油中维生素A和不同构型维生素E含量

以石油醚为溶剂,用索氏提取法提取了黑芝麻、白花生、黑花生、葵花籽、大豆、棉花籽的油脂。油样品先用正己烷溶解,然后用甲醇定容,其中正己烷含量为20%（v/v）,用Hypersil ODS2 5μm色谱柱,甲醇为流动相,对所提油脂中维生素A、α-维生素E、γ-（β）维生素E、δ-维生素E含量进行检测。实验结果表明,在204nm波长下,维生素A、α-维生素E、γ-（β）维生素E、δ-维生素E在0²00μg/m L范围内与峰面积有良好的线性关系,标准曲线相关系数r均大于0.9978。维生素A、α-维生素E、γ-（β）维生素E、δ-维生素E加标平均回收率分别为97.83%、98.58%、98.75%、99.93%。      

不同类型大豆萌发期维生素E组分及含量的比较

为了探究大豆萌发期维生素E的变化规律,本实验以8种栽培大豆为实验材料,采用高效液相色谱(HPLC)法测定大豆萌发期维生素E组分及含量,并统计萌发期大豆的发芽率、发芽势以及胚根长。结果表明:HPLC法测定的结果重现性和精密度良好,可以准确定量大豆维生素E组分的含量。3个黄皮黄仁大豆、2个黑皮黄仁大豆和1个绿皮黄仁大豆均表现为γ-生育酚含量大于α-和δ-生育酚含量,且萌发期间变化趋势大致相同;仅绿皮绿仁大豆和黑皮绿仁大豆各组分含量表现为α-生育酚γ-生育酚δ-生育酚。差异显著性分析表明,黄仁大豆在第7天的α-生育酚含量最高,绿仁大豆在第1天含量最高。大豆萌发期间黑皮绿仁大豆SZ910的α-生育酚含量显著高于其他材料,进一步分析表明萌发期绿仁大豆中α-生育酚含量显著高于黄仁大豆,表明萌发期绿仁大豆较黄仁大豆具有更高的营养保健作用。     

不同品种葵花籽油抗氧化性研究

用超声波法提取S-31、MGS、内葵杂3号、T526、白葵杂9号5个品种葵花籽油,采用Schaal烘箱法加速氧化,比较加速氧化对不同品种葵花籽油过氧化值、酸值、碘值以及氧化后产生的共轭二烯与共轭三烯含量的影响,综合筛选出具有高抗氧化性的油葵品种.结果显示,S-31葵花籽油在氧化过程中过氧化值的变化量以及氧化后产生的共轭二烯与共轭三烯含量显著低于其余各品种(P＜0.05),且酸值的变化量显著低于内葵杂3号、T526、白葵杂9号,表明S-31品种抗氧化性较好.     

不同种类葵花籽油甘油三酯组成的比较

对来自我国葵花籽主产区的油用葵花籽和普通葵花籽进行油脂提取,并对两类葵花籽油甘油三酯组成和含量进行了测定及比较。结果表明:两类葵花籽油均由14种甘油三酯组成,其中LLL、OLL、PLL、OOL、SLL+OPL、OOO、OLS的含量之和均达到91%以上;两类葵花籽油的甘油三酯含量区间呈现完全包含或交错重叠的关系;除SSL+POS外,其他甘油三酯含量在油用葵花籽油中的差异比在普通葵花籽油中的差异更为显著。     

The vitamin D allowance of premature infants and their phosphorus-calcium metabolic status with different types of feeding and rickets prevention

The content of 25-hydroxycholecalciferol, calcium and phosphorus in blood serum was measured in 80 premature infants aged 12 to 120 days depending on the type of feeding and rickets prevention. Administration of vitamin D in a dose of 400 IU and increase of calcium consumption up to 110-120 mg and of phosphorus to 45-57 mg per kg body weight at the expense of calcinated cottage introduction into the diet provide for the optimal levels of 25-hydroxycholecalciferol and calcium in the blood of these children. Administration of calcium and phosphorus to children receiving breast feeding in doses of 80-90 and 33-37 mg/kg, respectively, is not sufficient for the maintenance of calcium homeostasis and endogenous supply with vitamin D even if the latter is given prophylactically. When children are fed with the mixture Maliutka, the maximal permissible dose of vitamin D may amount to 800 IU a day. Administration of vitamin D in a dose of 3750 IU is fraught with a danger of hypervitaminosis D in the presence of high alimentary supply with calcium and phosphorus and does not make calcium homeostasis return to normal in the presence of low supply with these mineral substances.     

不同品种葵花籽油氧化稳定性研究

为研究不同品种葵花籽油的氧化稳定性,采用Schaal烘箱法连续加热12 d,分别测定葵花籽油过氧化值、酸值、碘值、共轭二烯和共轭三烯含量,并用高效液相色谱法分析亚油酸与α-生育酚含量。结果表明:在氧化过程中油葵6号过氧化值在6 d时均显著低于其他各品种,共轭二烯含量显著低于T012244和内葵杂3号,碘值在9 d时显著高于内葵杂3号但与白葵杂6号和T012244差异不显著,酸值与共轭三烯含量在12 d时均显著低于白葵6号、T012244。油葵6号过氧化值、酸值和碘值在6 d内均未超过国标规定的标准。油葵6号中亚油酸与α-生育酚含量均显著高于其他各品种。油葵6号葵花籽油氧化稳定性较强。     

Oxidative changes in hazelnut,olive, soybean,and sunflower oils during microwave heating

The effects of microwave heating for 3, 6, and 9 min at a frequency of 2450 MHz on fatty acid composition, tocopherols, iodine value, free fatty acids (%), peroxide value, conjugated dienes and trienes, and hexanal contents of refined hazelnut, soybean, sunflower, and virgin olive oils were investigated. A significant (p < 0.05) decrease was observed in linoleic and linolenic acids contents of soybean oil during exposure to microwave heating. Tocopherol contents of oil samples significantly decreased (p < 0.05) during microwave heating. Free fatty acids of the samples slightly increased and iodine value showed reduction throughout the process. Conjugated dienes contents of samples showed an increasing trend up to the 6 min, followed by a reduction at 9 min. Conjugated triene fatty acids of all the samples significantly increased (p < 0.05) throughout the application. While peroxide value showed increasing trend up to the 3 min and sharply decreased at 9 min, hexanal contents of refined hazelnut, virgin olive, soybean, and sunflower oils increased 63, 28, 55, and 389 fold, respectively, after 9 min exposure to microwave heating. Kinetic analysis of data showed that the reaction orders for peroxide and hexanal formation were zero and first order, respectively, and in the tested oils the reaction rate followed the order: soybean oil ? sunflower oil ? hazelnut oil ? virgin olive oil for peroxide, and sunflower oil ? soybean oil ? hazelnut oil ? virgin olive oil for hexanal formation. It was concluded that hexanal could be considered as a parameter for evaluation of the quality of oils exposed to microwave heating.     

Aflatoxin B1 levels in groundnut and sunflower oils in different Sudanese states

In this article, the level of contamination of aflatoxin B₁ (AFB₁) in groundnut and sunflower oils was determined. The 241 oil samples were collected from Khartoum, Gezira, Kordofan and Algadarif states of Sudan and assessed for AFB₁ using high-performance liquid chromatography (HPLC). AFB₁ levels in groundnut oil samples ranged from 0.5 to 70 µg/kg and were 0.7 to 35 µg/kg in sunflower oil samples. High contamination was found in unrefined samples. It was concluded that AFB₁ levels in oil samples indicated that growing, harvesting, handling and storage of the crops were not done properly.     

The vitamin allowance of the pupils in a rural vocational and technical school and their prophylactic vitaminization]

The actual nutrition and providing with vitamins C and B1 was studied in boys aged 16-17 years, students of a rural trade school (Volsk of Saratov Province). Although the caloric value of their ration was high enough the content of animal proteins was only 42-48 g/day. The content of ascorbic acid in the ration comprised 48%, in the spring of 1987 it was 17%, and of 1988-29% of the recommended standard, vitamin B1 levels did not show seasonal differences. Vitamin C and B1 deficiencies in the spring were proved by their low excretion levels in urine, and by a low concentration of vitamin C and decreased activity of B1-dependent enzyme transketolase in the blood. Intake of "Undevitum" (1 dragee/day) during 4 months was conductive to the improvement of the student providing with vitamins.     

Effect of varying the vitamin E allowance on the contractile function of the heart muscle

Experimental rats received diets containing varying amounts of vitamin E (100, 12.5 and 0 mg alpha-tocopherol acetate/kg food) during 4 months. It was found that although subnormal intake (12.5 mg/kg) of DL-alpha-tocopherol resulted in a 60% decrease of its concentration in the rat blood serum, it induced a significant lowering in the hemolytic stability of red blood cells, pronounced impairment of the rats' myocardial contractile function was observed as compared to the animals which received optimal doses of the vitamin (100 mg/kg food). The impairment was expressed in a decrease of the tension developed, depression of Starling's curve (the ratio between the initial length and the tension developed), the lowering of the myocardial resistance to Ca2+ excess, resulting in a more rapid development of the calcium-induced contracture. An increased vitamin E deficiency (0 mg DL-alpha-tocopherol/kg food), an 11-fold lowering of tocopherol concentration in the blood and a drastically enhanced hemolysis of red blood cells did not lead to a further impairment of the myocardial contractile function parameters studied.     

Aflatoxins in sunflower seeds and unrefined sunflower oils from Singida,Tanzania

A total of 61 samples comprising sunflower seeds (40) and unrefined sunflower oils (21) samples collected randomly from Singida, Tanzania were analysed by Reverse Phase-high performance liquid chromatography (RP-HPLC). 15% (6/40) of the seed samples were contaminated with aflatoxin B₁ ranging from limit of detection (LOD) to 218 ng g^?1 with three of them exceeding the European Commission/European Union (EC/EU) and Tanzania Bureau of Standards (TBS)/Tanzania Food and Drug Authority (TFDA) maximum limits of 2 ng g^?1 for AFB₁ in oilseeds. The levels of total aflatoxins (AFT) in seeds ranged from LOD to 243 ng g^?1. Other aflatoxins, except AFG₂, were also detected. For the unrefined sunflower oils, the levels of AFB₁ ranged from LOD to 2.56 ng mL^?1. About 80.9% (17/21) of the analysed oil samples contained AFB₁ of which 17.65% (3/17) exceeded the EC/EU and TBS/TFDA maximum limits of 2 ng mL^?1. Other aflatoxins were also detected in the oils. The measured levels indicate there is a need for food quality education among food processors.     

Role of vitamin E and phenolic compounds in the antioxidant capacity,measured by ESR,of virgin olive,olive and sunflower oils after frying

The effect of lipid profile, vitamin E and total phenolic content was studied in relation to the antioxidant capacity (measured by ESR) of three edible oils (virgin olive, sunflower and olive oils), using short-time deep fat frying as a model. Physico-chemical changes in the oils were also studied. Samples were analysed before and after 15, 30, 45 and 60 min fryings. Determination of free radicals, by electron spin resonance spectroscopy, revealed the highest antioxidant capacity in virgin olive oil and sunflower oil. This parameter was mainly influenced by vitamin E content, followed by lipid profile and phenolic content. The frying procedure decreased the antioxidant capacity in all tested oils. Sunflower oil underwent more chemical changes by frying than did olive and virgin olive oils. Antioxidant capacity of the edible oils was correlated with polar components and ultraviolet indices but not with peroxide index or acidity value. The use of ESR, as a rapid and very sensitive method for determining antioxidant capacity of edible oils, is suggested.     

PAHs content in sunflower,soybean and virgin olive oils: Evaluation in commercial samples and during refining process

Polycyclic aromatic hydrocarbons (PAHs) are environmental carcinogenic compounds that may contaminate vegetable oils and their levels can be reduced by refining. In order to understand the influence of the refining steps, the content of 15 PAHs was assessed throughout alkaline refining in soybean, sunflower and olive oil samples. Eight commercial brands of these oils were also analysed. The analytical method involved a liquid–liquid extraction, a solid-phase clean up (C₁₈ and Florisil) followed by RP-HPLC with fluorimetric detection. The total PAHs content in the studied samples can be considered generally low. The light PAHs (2–4 rings) were predominant. Virgin olive oils showed the highest values (max. 26 μg/kg). An evident decrease of PAHs contents during alkaline refining was observed (71%, 88% and 85% in sunflower, soybean and olive oils, respectively) being more pronounced in light PAHs. Neutralization and, particularly, deodorization were the more effective steps contributing to the PAHs decrease. Bleaching was responsible for a slight increase in the PAHs content in soybean and olive oils.     

维生素E对致敏大鼠机体敏感性的影响

目的研究补充不同剂量、不同接触时间的维生素E对致敏SD大鼠机体敏感性的影响。方法取8周龄雌性SD大鼠,按体重随机分为5组,每组25只,每天经口分别给予不同剂量的维生素E(2.3、6.9、13.8mg/kg),在第2周、3周、4周、5周、6周时,每组分别取出5只动物,腹腔注射给予10 mg/只OVA致敏,一周后使用50 mg/只OVA刺激,检测各组动物血清中总Ig E、特异性Ig E和Ig G1、血浆中组胺、m MCP-1和细胞因子(IFN-γ,IL-4)的水平,大刺激后处死动物,取心脏、肝、脾、肾、胸腺、空肠、肠系膜淋巴结等脏器,并对这些脏器进行组织病理学观察。结果经口给予高剂量维生素E 6周,OVA产生的免疫学反应强度受到了显著的抑制作用,总Ig E、特异性Ig E、特异性Ig G1、IL-4以及组胺水平显著降低,IFN-γ水平显著升高,随接触时间的延长呈增高的趋势。且高剂量处理组动物免疫学反应强度显著低于OVA对照处理组,对致敏SD大鼠的机体敏感性起到了有效的调节作用。结论维生素E能够降低致敏动物机体对卵白蛋白的敏感性,也抑制了免疫系统对卵白蛋白产生的免疫学反应。