家庭烹调对鲟鱼中脂肪酸和胆固醇的影响

对杂交鲟鱼（Acipenser baerii×A. schrenckii）进行了清蒸、油煎、微波、微波烤、烤箱烤和压力锅煎6 种家庭烹调处理,测定其脂肪和胆固醇含量、脂肪氧化指标和各脂肪酸含量的变化。结果表明,所有烹调方法均降低了n-3/n-6多不饱和脂肪酸含量的比值,其中压力烹调比值最高（0.85）,清蒸次之（0.83）,而烤箱烤最低（0.73）。胆固醇保存率以清蒸和压力锅煎最高,两种处理间无显著差异。烹调后样品酸价和硫代巴比妥酸值上升而过氧化值下降,并与样品的胆固醇含量相关。清蒸和压力烹调中脂肪酸和胆固醇变化相对较少,可能与其密闭烹调条件造成氧化程度较低有关。     

抗氧化剂对胆固醇高温氧化抑制作用研究

探讨了11种抗氧化剂对胆固醇在空气和猪油中高温氧化的抑制作用以及对猪油过氧化值的影响。使用气相色谱-质谱联用技术检测高温氧化前后胆固醇含量变化,同步检测5种主要高温氧化产物(7α-羟基胆固醇、7β-羟基胆固醇、5,6β-环氧基胆固醇、5,6α-环氧基胆固醇、7-酮基胆固醇)。结果表明:多种抗氧化剂对胆固醇在空气中的高温氧化可以起到明显的抑制作用,以芦丁、槲皮素、绿原酸、咖啡酸效果最好。胆固醇在猪油中氧化程度较弱,11种抗氧化剂中只有咖啡酸表现出较好的抑制作用。过氧化值的对比研究发现:咖啡酸、橙皮素、柚皮素、维生素E、BHT均有一定的降低过氧化值作用,其中以咖啡酸效果最佳。不同抗氧化剂对空气中胆固醇高温氧化的抑制有很大不同,从而有助于筛选具有较强高温抗氧化能力的抗氧化剂。咖啡酸的高温抗氧化能力值得关注。     

干腌火腿中胆固醇氧化物含量研究

胆固醇由于含有不饱和键,极易发生自动氧化,产生胆固醇氧化物(Cholesterol Oxidation Products,COPs)。生物学研究表明COPs具有细胞毒性、致突变性和致癌性。干腌火腿因其加工周期长,腌制过程中过量的食盐、脱水、适宜的温度以及长期暴露在空气中等因素都会促进胆固醇氧化,并形成COPs。采用气相色谱-质谱联用法测定干腌火腿中COPs含量。结果表明,新鲜火腿和陈放一年的火腿肌肉组织中COPs总量分别为0.59 mg/kg和2.12 mg/kg,其中7-酮基胆固醇含量最高;脂肪组织中COPs总量分别为2.49 mg/kg和4.14 mg/kg,其中胆甾烷-3β,5α,6β-三醇和7-酮基胆固醇含量较高。     

氧化反应中胆固醇与甘油酯相互作用

<正> 前言研究表明胆固醇和甘油酯的氧化产物对人体有害。最近采用新的色谱分析手段,能分离和鉴别出多种胆固醇的氧化产物,例如在煎炸的鸡肉中检测出6—53ppm胆固醇的环氧化物;在干燥的蛋黄粉中检测出7-羧基胆固醇(74ppm),7-酮     

吃鸡蛋必知的十个问题

正在营养学界,鸡蛋一直有"全营养食品"的美称。的确,鸡蛋是优质蛋白质的最佳来源之一,其中还含多种维生素和矿物质,少量ω-3脂肪酸及大量卵磷脂、叶黄素等保健成分。但对于这种高营养食品,人们对它的了解并不多。营养专家就此对人们应该知道的10个问题进行了解答。鸡蛋的哪种吃法最健康?中国农业大学食品学院副教授范志红指出,从蛋黄的维生素损失和蛋白质消化率来说,如果不煎炸到发黄发脆的程度,蒸、煮、炒、煎等烹调方法之间的差异并不大。但按胆固醇的氧化程度和受热程度考虑,各种烹调方法的健康排序如下,A级:蒸煮鸡蛋;B级:煮荷包蛋、蛋花汤;C级:炒鸡蛋、鸡蛋煎饼;D级:蛋黄。腌鸡蛋会造成营养损失吗?腌鸡蛋是指加盐腌制过的咸鸡蛋。腌制过程中营养损失并不大,但有研究表明,腌鸡蛋中的胆固醇氧化程度较大,形成的胆固醇氧化产物会对心血管造成危害。茶叶蛋也是腌鸡蛋的一种,而且茶叶等抗氧化物质的存在会减轻     

中式香肠中脂肪氧化对蛋白质氧化的影响

以中式香肠为研究对象,通过对加工、储藏过程中包装、温度、光照以及抗氧化剂的不同处理,建立中式香肠的脂肪氧化模型,结合对其蛋白质氧化的跟踪检测,分析了中式香肠中脂肪氧化与蛋白质氧化之间的相关性。结果表明:对于脂肪氧化的抑制作用,有效抑制了蛋白质氧化形成羰基类物质,且与脂肪氧化初级和次级产物均表现较好的相关性;脂肪氧化对于蛋白质游离硫醇基流失的促进作用是由脂肪氧化次级产物挥发性醛类物质引起的。     

核桃油氧化及抗氧化调控研究进展

摘要：核桃油富含多不饱和脂肪酸（PUFA）、单不饱和脂肪酸（MUFA）和多种营养素,具有多种生物活性。核桃油的稳定性较差,易发生氧化酸败,为提高核桃油的品质,延长其货架期,综述了近年来有关核桃油氧化劣变的影响因素和核桃油抗氧化调控措施的研究进展。核桃油氧化劣变的影响因素有内部因素,如脂肪酸组成、内源性物质的抗氧化能力,也有外部因素,如储藏条件、提取工艺。可以采用微胶囊技术、复配调和其他抗氧化性强的油脂,以及添加抗氧化剂的方式延缓核桃油氧化酸败。     

食用植物油抗氧化的研究进展

食用植物油能够为机体生长和代谢提供能量,补充人体必需脂肪酸和多种微量营养素。植物油中丰富的不饱和脂肪酸在加工和贮藏过程中易受环境因素影响而发生氧化酸败,产生一系列有害氧化产物,食用后对机体生理健康造成一定威胁。因此,本文简述了食用植物油氧化诱因、主要氧化途径-自动氧化机制及油脂氧化的危害,具体从低温储藏、气调储藏和添加单一或复配抗氧化剂方面综述了食用植物油抗氧化研究进展,并对目前食用植物油氧化和抗氧化措施等研究领域存在的问题进行了深入探讨,以期为食用植物油氧化稳定性相关研究提供一定参考。     

胆固醇受热氧化产物研究

对胆醇醇受热氧化情况进行了研究。采用毛细管气相色谱法分离检测胆固醇氧化产物。胆固醇于90℃加热2h和高温下加热初期（150℃，10min以内），没有明显的氧化物生成。但高温加热时间较长（20min以上）时，自氧化反应很容易发生，共有6种氧化产物（5β、6β－环氧化胆固醇、5α、6α－环氧化胆固醇、3β，5α，6β－胆甾烷三醇、6－酮基胆固醇、7－酮基胆固醇、25－羟基胆固醇）被确定。胆固醇氧化产物组成和生成量与胆固醇的量、加热温度及加热时间有关。     

家庭压力烹调对红小豆抗氧化能力的影响

研究家庭压力烹调对红小豆抗氧化成分及抗氧化能力的影响。以常压烹调为对照,检测不同压力和时间烹调后的总多酚、总黄酮含量及DPPH自由基清除能力、铁还原抗氧化能力(FRAP)、氧自由基吸收能力(ORAC)。结果显示:总黄酮、总多酚和3种抗氧化能力指标有较高相关性。与生样比较,各烹调处理的总黄酮、总多酚和各抗氧化能力均有下降。但总体来说,家庭压力烹调对抗氧化物质和抗氧化能力的保存效果并不逊色于常压蒸煮烹调。在包括常压烹调在内的各烹调处理中,122 k Pa/20 min的处理可以最好地保留红小豆中的酚类物质和抗氧化能力。     

Cholesterol and Lipid Oxidation Products in Cooked Meat as Affected by Raw-Meat Packaging and Irradiation and by Cooked-Meat Packaging and Storage Time

Aerobic packaging significantly increased cholesterol oxidation products (COPs) and thiobarbituric acid reactive substances (TBARS) in cooked turkey, pork, and beef patties after 7‐d storage, but vacuum packaging was very effective in preventing cholesterol and lipid oxidation. Packaging of meat after cooking had a much stronger effect on COPs formation than before cooking, and irradiation had only a minor effect. The amount of total COPs correlated well with TBARS in cooked meat. Turkey had the highest rates of COPs and TBARS formation and beef had the lowest rates after 7‐d storage, which were closely related to the fatty acid composition of meats. 7a‐hydroxycholesterol, 7p‐hydroxycholesterol, and 7‐ketocholesterol were the major COPs detected in all 3 cooked meat patties.     

Effect of different cooking methods on lipid oxidation and formation of free cholesterol oxidation products (COPs) in Latissimus dorsi muscle of Iberian pigs

The aim of this work was to study the influence of different cooking methods (grilled (GR), fried (FP), microwave (MW) and roasted (RO)) on lipid oxidation and formation of free cholesterol oxidation products (COPs) of meat from Iberian pigs that have been fed on an intensive system. Moisture and total lipid content, TBARs, hexanal and COPs were measured in Latissimus dorsi muscle samples. Cooking did not produce changes in total lipid content in meat but induced significantly higher lipid oxidation (TBARs and hexanal values) (p < 0.001) and cholesterol oxidation (COPs) (p < 0.01). When the different cooking methods were studied, the grilled method was the least affected by lipid oxidation (TBARs and hexanal) compared to the others. There were no significant differences among different cooking methods on COPs values. The most abundant cholesterol oxides were both 7α-hydroxycholesterol and 7β-hydroxycholesterol in all groups studied.     

Effect of dietary α-tocopherol supplementation and gamma-irradiation on α-tocopherol retention and lipid oxidation in cooked minced chicken

The effects of dietary α-tocopherol supplementation and gamma-irradiation on α-tocopherol retention and lipid oxidation in cooked minced chicken during refrigerated storage were studied. Minced breast and thigh meat from broilers fed diets supplemented with 100, 200 or 400 mg α-tocopheryl acetate/kg feed was irradiated at 2.5 or 4.0kGy. Cooked irradiated and unirradiated meat was stored at 4 °C for 5 days. α-Tocopherol concentrations increased with increasing dietary supplementation. Concentrations decreased during storage, but retention was not affected by irradiation. Lipid stability was determined by measuring the formation of thiobarbituric acid-reacting substances (TBARS) and cholesterol oxidation products (COPs) during storage. TBARS and COPs increased during storage and were reduced by increasing levels of dietary α-tocopheryl acetate supplementation. Irradiation accelerated TBARS formation during storage, but this was prevented by supplementation with 200 mg α-tocopheryl acetate/kg feed. Irradiation tended to increase COPs during storage, although no consistent effects were observed. In general supplementation with over 400 mg α-tocopheryl acetate/kg feed may be required to control cholesterol oxidation in minced chicken. The results suggest that, overall, irradiation had little effect on lipid stability in α-tocopherol-supplemented meat following cooking and storage.     

Cholesterol photosensitised oxidation of horse meat slices stored under different packaging films

The effect of the type of packaging film (transparent vs. light-protecting red film) was evaluated on the formation of cholesterol oxidation products (COPs) in refrigerated horse meat slices stored in retail conditions under light exposure for 8 h. In meat wrapped with a transparent film, COPs increased from 233 (control) to 317 μg/g of fat, whereas the red film delayed cholesterol oxidation and offered protection against COPs formation, since COPs decreased from 173 (control) to 139 μg/g of fat after 8 h of light exposure. In addition, light opened the epoxy ring and led to the formation of triol, which was actually absent at T_0. A proper packaging film may represent a useful strategy to retard oxidative degradation in a light-sensitive, high pigment- and fat-containing food, such as horse meat.     

Differential Inhibitory Effect of alpha-, beta-, gamma-, and delta-Tocopherols on the Metal-Induced Oxidation of Cholesterol in Unilamellar Phospholipid-Cholesterol Liposomes

ABSTRACT: Cholesterol oxidation products (COPs) are present in biological tissues and in foods. The inhibitory effect of antioxidants, such as tocopherols, on COPs formation has been only partially investigated. The antioxidant effect of dl alpha-, dl beta-, dl gamma-, and dl-delta tocopherol on the metal-induced oxidation of phosphatidylcholine (PC): cholesterol liposomes was assayed. Formation during liposome oxidation of six different COPs was monitored by gas chromatography. dl alpha-, and dl gamma-tocopherol show good inhibitory effect against PC-fatty acid oxidation and also on COPs formation. dl delta-Tocopherol is less effective than the alpha-and gamma-homologous, beta-tocopherol being unable to prevent PC and cholesterol oxidation. dl alpha-, and dl gamma-Tocopherol are more effective to prevent the oxidation of the lateral chain of cholesterol molecule. At the highest tocopherol concentration assayed, dl alpha-tocopherol shows prooxidant effect, enhancing liposomal oxidation and COPs formation. It is concluded that the tocopherols assayed can inhibit cholesterol oxidation but to a different degree.     

Lipid and Cholesterol Oxidation in Whole Milk Powder during Processing and Storage

The influence of animal feed quality on lipid and cholesterol oxidation in whole milk powder was investigated. Powders from a herd receiving a ‘supplemented’ diet showed reduced PV (p < 0.01) and TBARS (p < 0.09) compared to a ‘restricted’ herd, after storage in both vacuum and sachet-packs and less (p < 0.003) cholesterol oxidation products (COPs). High pre-heating temperatures resulted in higher levels of PV, TBARS and COPs in fresh whole milk powders than low pre-heat temperatures, but after storage the reverse occurred. Superior animal feed quality and proper control of processing and storage conditions enhanced oxidative stability of whole milk powder. Lipid and cholesterol oxidation were positively correlated (p < 0.001).     

Inhibition of cholesterol oxidation in marinated foods as affected by antioxidants during heating

Chinese marinated foods rich in cholesterol, such as eggs and pork, can be susceptible to formation of carcinogenic cholesterol oxidation products (COPs) during prolonged heating. The objectives of this study were to compare the effects of various antioxidants on the inhibition of COPs in marinated eggs, pork and juice. The various COPs in marinated food samples were analyzed by a GC–MS technique. The incorporation of antioxidants, vitamin C, vitamin E, BHA and trolox were all effective in inhibiting COPs formation, with vitamin C being the most pronounced in marinated eggs, and BHA in marinated pork and juice. The inhibition effect increased with increasing levels of BHA and trolox. However, vitamin E was more effective at a low level (0.02%) than at a high level (0.1%), probably because of prooxidant activity of the latter. The same phenomenon also occurred for 0.1% vitamin C in marinated eggs, but a reversed trend was observed in marinated pork and juice. The residual amounts of each antioxidant in marinated eggs, pork and juice were also determined by HPLC.     

Effect of feeding fat sources on the quality and composition of lipids of precooked ready-to-eat fried chicken patties

The effect of feeding fat sources on the quality and composition of lipids of raw meat and precooked ready-to-eat fried chicken patties was studied. Two homogeneous groups of broilers were fed with animal fats and vegetable oils, respectively. A traditional technology (flash-frying and humid steam-convection oven cooking) was employed to produce the patties. Lipid hydrolysis (total fatty acids, free fatty acids and diacylglycerols) and oxidation (peroxide value (POV) and cholesterol oxidation products (COPs)) were evaluated in the initial, intermediate and final products. Lipid hydrolysis and oxidation were more intense in ground raw meat obtained with animal and vegetable fat integration, respectively. However, these differences tended to decrease along the technological process, due to the addition of other ingredients and the oil absorption. Although flash-frying and humid steam-convection oven cooking promoted lipid degradation, the overall quality of the precooked chicken cutlets was acceptable (low POV and COPS values) and greatly depended on the quality of the raw meat and the frying oil.     

Oxidised cholesterol in milk and dairy products

Cholesterol is found in animal foods. It can be oxidised in various ways and cholesterol oxidation products (COPs) are formed. Such products are often found in animal foods including dairy products. Recently published results suggest that the contents of COPs in milk and dairy products is very small and does not confirm the results of earlier studies. A higher concentration of COPs can be found only in processed dairy products exposed to harsh storage conditions where the impact of oxygen and light or oxygen and low water activity are concomitant.     

Effect of electron-beam irradiation on cholesterol oxide formation in different ready-to-eat foods

A study of the formation of ¹cholesterol oxidation products (COPs) has been carried out in four ²ready-to-eat (RTE) foods (cooked ham, Spanish Serrano ham, minced beef, and soft cheese). The samples were previously treated with electron-beam irradiation between 1 and 8 kGy. Three COPs, 25-hydroxycholesterol, 7-ketocholesterol and 6-ketocholestanol, were extracted together with the lipid fraction using chloroform. Then, COPs were isolated by sample clean up using ³solid phase extraction (SPE) and were analyzed by ⁴high performance liquid chromatography with ultraviolet detection (HPLC-UV). Method validation was established by precision and recovery studies. Results showed that non-irradiated cheese and cooked ham samples did not contain COPs. In general, an increase in COP content was observed in all cases when the irradiation dose increased, although this increase was not linear. The 6-keto COP was not detected in any of the RTE food samples studied regardless of the irradiation dose.

Industrial relevance

Nowadays, changes in dietary habits have produced an important increase in consumption of prepared foods thus increasing microbiological contamination risks; consequently, it is necessary to apply easy methods, able to be implanted in industrial production lines, and which eliminate potential contaminants and enhance shelf life. The application of E-beam irradiation to vacuum packed ready-to-eat (RTE) food of animal origin could be a useful technique for sanitization purposes; besides, it is a clean, rapid and environmentally friendly treatment. During this treatment cholesterol oxide products (COPs) may be formed. They have received considerable attention in recent years because of their biological activity which has been associated with human diseases, such as the inhibition of cholesterol biosynthesis, atherosclerosis, changes in membrane properties, cytotoxicity, mutagenesis and carcinogenesis. Therefore, COP analysis in food samples of animal origin is of great interest.In this work, an increase in the 25-OH and 7-keto COP content has been detected after E-beam irradiation with doses from 1 to 8 kGy, which is in the upper accepted limit in other foods, but final COP concentrations found in the foodstuffs studied here were at least one order of magnitude lower than those which produce toxic effects in in vivo and in vitro experiments. Analysis was made by HPLC with UV detection; so, two COPs with absorption properties were used as targets.