Cooking effects on fat and fatty acids composition of chicken muscles

Total lipids content of chicken breast and thigh muscles were investigated. Effects of boiling and roasting cooking treatments on these muscles were also studied to evaluate the probable changes in their fat contents, values of acid, peroxide and thiobarbituric acid (as measures for lipolysis and oxidative deterioration of fat) as well as to estimate their fatty acids (saturated and unsaturated) composition. The obtained results were tabulated and discussed.     

Effect of cooking methods on fatty acids,conjugated isomers of linoleic acid and nutritional quality of beef intramuscular fat

The effect of boiling, microwaving and grilling on the composition and nutritional quality of beef intramuscular fat from cattle fed with two diets was investigated. Longissimus lumborum muscle from 15 Alentejano young bulls fed on concentrate or pasture was analyzed. Cooking losses and, consequently, total lipids, increased directly with the cooking time and internal temperature reached by meat (microwaving > boiling > grilling). The major changes in fatty acid composition, which implicated 16 out of 34 fatty acids, resulted in higher percentages in cooked beef of SFA and MUFA and lower proportions of PUFA, relative to raw meat, while conjugated linoleic acid (CLA) isomers revealed a great stability to thermal processes. Heating decreased the PUFA/SFA ratio of meat but did not change its n−6/n−3 index. Thermal procedures induced only slight oxidative changes in meat immediately after treatment but hardly affected the true retention values of its individual fatty acids (72–168%), including CLA isomers (81–128%).     

烹饪方式对胡麻油不饱和脂肪酸的影响

通过设计不同温度下、不同加热时间、冷锅冷油及热锅冷油试验,分析其对胡麻油不饱和脂肪酸的影响。结果表明:不同加热温度、时间对胡麻油不饱和脂肪酸影响显著,随着加热温度的升高,不饱和脂肪酸含量有下降趋势,相同加热温度下时间越长,不饱和脂肪酸含量下降越快。冷锅冷油和热锅冷油的烹饪方式对胡麻油不饱和脂肪酸影响差异不显著,随着加热温度的升高,某未知物质有了显著升高,冷锅比热锅更容易生成该物质且变化明显。加热温度、加热时间与胡麻油不饱和脂肪酸呈负相关性。     

Comparison of the effects of four cooking methods on fatty acid profiles and nutritional composition of red mullet (Mullus barbatus) muscle

This study was performed to examine the effects of different cooking methods (frying, steaming, oven cooking, and microwave cooking) on proximate chemical composition, mineral contents, and fatty acids profiles of red mullet (Mullus barbatus) fillets. The frying process caused a significant increase in fat content (from 13.37±0.04 to 34.44±0.20 g/100 g d.w.) and reduced the proportion of the palmitic acid of 50.73% and saturated fatty acids of 56.9%. While, the proportion of polyunsaturated fatty acids (PUFA) increased from 4.04% of total fatty acids for raw fillet to 49.17% of total fatty acids for fried fillets. The steamed, oven-cooked, and microwave-cooked fillets showed the best proportion of fat content, PUFA, and ω-6/ω-3 ratio as compared with fried red mullet fillets. Na, Mg, and Zn contents of cooked fish fillets significantly decreased.     

Effect of sampling fat location and cooking on fatty acid composition of beef steaks

To investigate the impact of sampling fat location and cooking on fatty acid composition of beef steaks, 21 raw steaks from crossbred steers were dissected to obtain outer (OSC) and inner subcutaneous fat (ISC), seam fat, marbling, and lean muscle. Twenty-one cooked steaks were dissected to obtain OSC, ISC, seam fat, surface and inner muscle. Trans-vaccenic acid and c9, t11-CLA percentages were lower (P < 0.05) in lean muscle than subcutaneous (s.c.) fat or marbling. Monounsaturated: saturated fatty acid ratios were lower (P < 0.05) in seam fat and marbling than s.c. fat or lean muscle. Linoleic and linolenic acid levels were highest in lean muscle and longer chain n−6 and n−3 fatty acids were only detected in lean muscle. Cooking did not change fatty acid composition dramatically except that n−6: n−3 ratio in s.c. and seam fat decreased after cooking (P < 0.05).     

多个番茄果实样品脂肪酸含量及组成比较分析

采用索氏提取法提取8个番茄果实样品中的粗脂肪,用KOH-甲醇溶液对脂肪酸进行甲酯化,以37种脂肪酸标品为对照,采用气相色谱分析法测定其脂肪酸含量及组成。结果表明:番茄果实干物质平均含量5.86%,种子含量0%～0.51%,粗脂肪平均含量6.97%;番茄果实样品间脂肪酸总量差异明显,最大可达10倍以上;番茄果实脂肪酸总量与种子量一定程度正相关;番茄果实脂肪酸相对百分含量有一定差异,其主要脂肪酸组成及含量为棕榈酸13.2%～26.4%、硬脂酸0%～6.2%、油酸0%～27.5%、亚油酸50.5%～70.9%、亚麻酸2.5%～20.0%。研究结果可为番茄育种、栽培和资源综合开发利用提供参考。      

微波处理对油脂脂肪酸组成影响研究进展

该文介绍微波作用原理及其优点,综述微波处理对油脂脂肪酸影响,并展望微波对油脂脂肪酸影响的研究前景。     

伊拉兔肉肌内脂肪酸组成及温度对其脂肪氧化的研究

研究了伊拉肉兔后腿肉的肌内脂肪含量,并分析测定了其脂肪酸组成,同时研究了兔腿肉在常温(15±0.5)℃和低温(4±0.5)℃贮藏条件下的脂肪氧化稳定性。结果表明,兔腿肉肌内脂肪主要含有19种脂肪酸,其中棕榈酸(16∶0)、硬脂酸(18∶0)、油酸(18∶1)、亚油酸(18∶2)的总含量占脂类总脂肪酸含量的71.06%左右。伊拉兔肉肌内脂肪中主要是不饱和脂肪酸,尤以多不饱和脂肪酸居多。在常温(15±0.5)℃和低温(4±0.5)℃贮藏条件下,兔腿肉POV、TBA值的差异极显著(p<0.01)。常温条件下,第5d兔肉出现异味并逐渐变成臭味,而低温条件下,第7d才开始出现轻微异味,低温冷藏对保证肉品质量有重要意义。      

Nutrient composition of australian fresh retail sausages and the effects of cooking on fat content

Three types of fresh sausages (beef, thick and thin; and pork, thick) were purchased in ten Sydney suburbs and analysed as composite samples for proximate principles, carbohydrates, vitamins, minerals, fatty acids and cholesterol. Fat, moisture and meat species were also analysed in individual purchases. In a controlled experiment replicate samples of sausages were analysed for moisture and fat, raw and after cooking by grilling, dry-frying, shallow-frying and deep-frying. Results indicated widespread use of cow, pig and sheep meat in all types of sausages regardless of label identification. Some purchased sausages exceeded regulation limits for fat and starch content. Fat retention was lowest in beef sausages cooked by frying rather than grilling. Pork sausages retained most of their fat on cooking, regardless of method.     

烹饪时间对鱼肉中脂肪酸的影响

目的 考察不同烹饪时间对鱼肉中脂肪酸营养价值的影响, 并对不同鱼类的适宜烹调时间进行评价。方法 采用清蒸的方式对秋刀鱼、石斑鱼、鲫鱼和罗非鱼进行烹调, 利用氯仿-甲醇提取法提取鱼肉脂肪酸, 通过气相色谱技术(gas chromatography, GC)对鱼肉中脂肪酸进行定性定量, 讨论烹饪时间对不同鱼肉中脂肪酸含量变化的影响。结果 随着烹饪时间的增加, 4种不同种类的鱼肉中不饱和脂肪酸的含量都呈现下降趋势, 当烹饪时间为0.5~1.0 h时, 不饱和脂肪酸二十碳五烯酸(eicosapentaenoic acid, EPA)、二十二碳六烯酸(docosahexaenoic acid, DHA)、油酸、亚油酸、亚麻酸含量下降速率最快并且产生有害脂肪酸(反式脂肪酸), ω-6/ω-3脂肪酸比值也呈现出上升趋势, 鱼肉脂肪酸营养价值降低。结论 在对鱼肉进行烹饪时, 应严格控制鱼肉烹饪时间在0.5 h左右, 才能有效的保证鱼肉中脂肪酸的营养价值。     

Effects of a high fat diet on long-chain fatty acids composition in rats serum and liver

A reliable and sensitive technique had presented to monitor the content of long-chain fatty acids (LCFAs) in biological materials. The purpose of this study was to report a method for separation and quantification of LCFAs by capillary gas chromatography (GC) with better recovery. With this method, we detected some changes of LCFAs in the serum and liver of rat fed with high fat diet. The result showed that the levels of C22:0, C22:6, C26:0 of serum of the high fat group were higher than that of the control group (P < 0.01); and the levels of C22:6, C26:0 of liver of the high fat group were higher than that of the control group (P < 0.01), but the levels of C22:0 and C24:0 of liver of the high fat group were lower than that of the control group (P < 0.01). It indicated that a high fat diet had an adverse effect upon normal metabolism.     

Impact of milking frequencies on the level of free fatty acids in milk, fat globule size, and fatty acid composition

The aim of the present study was to study the effect of milking cows 4 times daily on free fatty acids (FFA) in the milk compared with milking twice daily. An experiment was performed during 2 wk in which half udders in 11 cows were milked 2 or 4 times daily. Milk yield was measured, and milk was analyzed for fat content, FFA, fatty acid composition, fat globule size, and activity of γ-glutamyl transpeptidase. Concentration of FFA was greater (1.49 mEq/100 g of fat) in milk from half udders milked 4 times daily than in milk from the half udders milked twice daily (1.14 mEq/100 g of fat). Further, it was noted that milk from the half udder milked 4 times daily contained milk fat globules with larger average diameters. Increased milking frequency increased milk yield by 9% compared with the udder half milked twice daily, but fat content and fat yield were not affected. The results are of importance for further understanding the mechanisms behind the increased content of FFA that is frequently observed in automatic milking systems.     

两种辐照方式对贵州腊肉中脂肪酸成分的影响

目的 研究了不同辐照处理对贵州腊肉中脂肪酸的影响。 方法 通过气象色谱法(GC)对贵州腊肉样品中脂肪酸的种类和含量进行了分析,并研究了_⁶⁰Co-γ 射线辐照和高能电子辐照两种辐照方法在0-5 kGy不同辐照剂量对腊肉中脂肪酸成分的影响。 结果 贵州腊肉样品中共检测出24种不同的脂肪酸,包括14种饱和脂肪酸(SFA),10种不饱和脂肪酸(UFA),未检测出反式脂肪酸(TFA)。辐照处理会导致腊肉中饱和脂肪酸含量上升,不饱和脂肪酸含量下降,产生了新的饱和脂肪酸C8:0和C10:0。高能电子辐照在3 kGy以下剂量时对样品影响更大,而剂量大于3 kGy时则_⁶⁰Co-γ辐照对样品中脂肪酸影响更大。 结论 辐照处理会影响腊肉中脂肪酸的含量和种类,但未产生有害的反式脂肪酸。两种辐照方式的能量大小和穿透能力存在一定差异,但对样品脂肪酸影响趋势基本一致。     

Effect of processing methods on spinach: Proximate composition in fatty acids and soluble protein

The proximate composition and fatty acid content of spinach were determined in two processing stages. Crude protein and ash content were 2.89% and 1.96%, respectively. The total lipid content was 0-61%. The predominant fatty acids were palmitic (16:0), hexadecadienoic (16:2), hexadecenoic (16:1), stearic and hexadecatrienoic (18:0 and 16:3), oleic (18:1), linoleic (18:2) and linolenic (18:3). Little loss was observed as a result of processing. Soluble protein content showed losses of up to 87% during processing.     

不同蒸煮方式下不同链长脂肪酸对板栗淀粉特性的影响

目的 研究不同蒸煮方式下不同链长脂肪酸与板栗淀粉（chestnut starch, CS）复合对板栗淀粉特性的影响。方法 通过测定淀粉及淀粉-脂质复合物的粒径大小,短程有序度、结晶度、糊化特性和流变特性,探究脂肪酸碳链长度和蒸煮方式对CS性质的影响。结果 脂肪酸的加入降低了CS颗粒尺寸、结晶度和短程有序性,增强了CS持水能力。同一蒸煮方式下,以板栗淀粉-月桂酸复合物变化最为明显,其次依次为板栗淀粉-肉豆蔻酸复合物、板栗淀粉-棕榈酸复合物。与常压蒸煮相比,高压蒸煮后淀粉持水能力增强,结晶结构更有序;短期老化淀粉的储能模量G''降低,损耗角正切值tan δ升高,表明抗短期老化性能提升。结论 不同碳链脂肪酸与CS 复合,短链脂肪酸及高压蒸煮复合效果更优,复合体系复合率更高,持水性能和抗短期回升效果更好。     

微波蒸煮对米粉品质的影响

考察不同微波功率对浸泡与未浸泡两种预处理米粉品质的影响,通过失重率、碘蓝值、酶解力、质构特性的检测,优化微波蒸煮条件,为微波即食米粉的开发提供理论依据。实验结果表明浸泡过程对米粉的蒸煮品质影响较小;米粉的失重率、硬度和粘结性随着微波功率的提高而增加,回弹性和酶解力受微波功率影响较小;600W微波功率蒸煮的米粉碘蓝值最高。