猪五花肉在三种红烧工艺加工过程中的脂肪氧化规律

目的:研究红烧肉在制作过程中工艺对脂肪氧化和脂肪酸含量变化的影响。方法:以上海本帮、湖南毛氏、东北传统三种工艺红烧肉为研究对象,以其烹制过程中的不同时间(原料肉、炖煮0、30、60、90 min)为取样点,分析三种红烧肉脂肪层脂肪含量、过氧化值、硫代巴比妥酸值和脂肪酸组成的变化。结果:三种工艺红烧肉制作过程中,肥肉层脂肪含量均显著下降(p<0.05),炖煮温度越高,脂肪含量下降越显著;POV值先增大后减小,在炖煮30 min达到最大值;TBA值在炖煮过程中显著增大(p<0.05);亚油酸(C18:2)、油酸(C18:1)、棕榈酸(C16:0)以及硬脂酸(C18:0)是五花肉脂肪中的主要脂肪酸,占总脂肪酸的90%以上,亚油酸(C18:2)含量显著下降,单不饱和脂肪酸含量上升。结论:三种工艺红烧肉制作过程中,脂肪含量下降、脂肪适度氧化、脂肪酸组成改变,红烧工艺对脂肪氧化和脂肪酸含量影响较大。     

猪五花肉红烧过程中脂肪和脂肪酸的变化规律

目的：探讨以猪五花肉为原料的红烧肉加工过程中脂肪和脂肪酸的变化,以期对红烧肉的风味、营养、质地等研究提供参考。方法：对红烧肉加工过程中原料、油炸、炖煮过程样品（0～2 h,每30 min取样）以及成品的粗脂肪含量、过氧化值（peroxide value,POV）、硫代巴比妥酸（thiobarbituric acid reactive substances,TBARS）值以及脂肪酸含量进行测定。结果：五花肉红烧过程中脂肪含量显著下降（P＜0.05）,成品红烧肉脂肪含量比原料肉下降12.14%;POV先增大后减小,在炖煮30 min达到最大值;TBARS值逐渐增大,在炖煮过程中变化显著（P＜0.05）;油酸、棕榈酸、亚油酸和硬脂酸是五花肉脂肪中的主要脂肪酸,在红烧过程中饱和脂肪酸（saturatedfatty acid,SFA）含量变化不大（P＞0.05）,单不饱和脂肪酸（monounsaturated fatty acid,MUFA）含量显著上升（P＜0.05）,多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）含量显著下降。结论：五花肉红烧过程中脂肪含量下降、脂肪发生适度氧化、脂肪酸组分构成发生了改变。     

红烧肉加工过程中脂肪降解、氧化和挥发性风味物质的变化研究

本文研究了原料肉、料酒腌制、油炸、大火炖煮0.5 h、小火炖煮0.5 h、小火炖煮1 h和成品红烧肉7个不同工艺阶段红烧肉基本理化指标及脂质降解、脂肪氧化和挥发性风味物质的变化状态。结果表明,成品肉水分含量比原料肉显著下降10.5%(p0.05)。pH值在前期变化不显著(p0.05),成品红烧肉时达到最大值为6.29。盐分含量在成品肉时达到最大为0.73%。硫代巴比妥酸值(TBA)在大火炖煮0.5 h后显著增加(p0.05),然后下降,成品红烧肉时又显著上升(p0.05),达到了0.62 mg MDA/kg。亚油酸(C18:2)、棕榈酸(C16:0)和硬脂酸(C18:0)是肉中的主要脂肪酸,加工过程中饱和脂肪酸总体呈下降趋势。加工过程中共检出挥发性风味物质86种,其中醛类,脂类和呋喃类是红烧肉中重要的挥发性风味物质。     

超声波在五花猪肉炖煮工艺中的应用

以五花猪肉为原料,研究传统工艺与超声工艺的走油与增香效果,通过测定加工材料脂肪层脂肪含量、过氧化值(peroxide value,POV)、硫代巴比妥酸反应物值(thiobarbituric acid reactive substances,TBARs)和脂肪酸组成为指标加以比较。结果表明:超声炖煮使原料中的脂肪含量下降13.32%,显著低于传统组(P0.05);在超声炖煮过程中,POV先增大后减少,超声促进了TBARs的上升(P0.05);超声炖煮120 min会使多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)显著下降,饱和脂肪酸(saturated fatty acid,SFA)值显著上升(P0.05);30 min会使单不饱和脂肪酸(monounsaturated fatty acid,MUFA)含量显著上升(P0.05)。超声可以促进炖煮中脂肪含量的下降、加速脂肪的氧化、促进猪肉炖煮香味的形成。     

鲈鱼风干成熟过程中脂质分解氧化规律

以鲈鱼(perch)为原料进行腌制风干成熟,通过分析测定加工过程中鲈鱼肌肉脂肪组成、脂肪酶及脂肪氧合酶(LOX)活力、硫代巴比妥酸值(TBARS)和过氧化值(POV)变化情况,探究其脂质分解氧化规律。结果表明:鲈鱼肌肉风干过程中总脂肪含量显著降低(P<0.05),中性脂质、磷脂含量在加工过程中显著下降(P<0.05),游离脂肪酸(FFA)含量显著上升(P<0.05),棕榈酸(C16:0)、硬脂酸(C18:0)、油酸(C18:1)、二十碳五烯酸(C20:5)和二十二碳六烯酸(C2 2:6)是FFA的主体成分;酸性脂肪酶、中性脂肪酶和磷脂酶活力在加工过程中总体上都呈显著下降趋势(P<0.05),且磷脂酶活力下降幅度最大,中性脂肪酶活力始终显著高于其他两种酶(P<0.05);而LOX活力持续下降,POV和TBARS值在整个加工过程中都呈现先增大后减小的变化趋势,说明风干成熟后期较高的温度能促进脂质氧化产物进一步分解,加速风味物质的形成。     

红烧肉炖制过程中的脂肪和脂肪酸变化

文章研究了原料肉煎制后、炖煮60,90,120,150min的红烧肉中基本营养指标的变化以及色泽、剪切力、脂肪氧化和脂肪酸的变化情况。结果表明:样品中的水分含量随炖制时间的延长呈下降趋势,脂肪含量显著降低(p0.05),蛋白质含量显著升高(p0.05)。原料肉经过煎制后硫代巴比妥酸值(TBARS)显著升高至0.95 mgMDA/kg,随着小火炖制时间的延长,TBARS值逐渐降低至0.28mgMDA/kg。经过不同时间的炖制,红烧肉中的饱和脂肪酸总体呈下降趋势,单不饱和脂肪酸(MUFA)总体呈上升趋势,与原料肉相比,炖制120min的样品中不饱和脂肪酸/饱和脂肪酸的比值从1.45上升到1.55,长时间小火炖煮提高了猪肉中油脂的营养价值。     

蓝圆鲹传统腌干过程中内源脂肪酶和脂质降解氧化的变化分析

为探明传统腌干鱼类加工过程脂肪降解氧化规律,本研究以蓝圆鲹为原料,采用传统腌干方法,测定传统腌干鱼加工过程(鲜鱼、腌制、浸泡脱盐、烘干、成品)5个加工阶段的内源性中性脂肪酶(neutral lipase,NL)、酸性脂肪酶(acid lipase,AL)、磷脂酶(phospholipase,PL)、脂肪氧合酶(lipoxygenase,LOX)活力变化,过氧化值(peroxide value,POV)、硫代巴比妥酸值(thiobarbituric acid value,TBARS)、脂肪酸含量变化,分析内源性脂肪酶与脂质降解、氧化的关系。结果表明:蓝圆鲹腌干过程中内源性脂肪水解酶活力均随着加工进程出现不同速率的降低情况,成品中NL、AL、PL活力保存率分别为:17%、57%、33%,LOX在腌干过程中活力显著增强(P0.05)。POV和TBARS均在加工过程中逐步上升,其中POV在烘干后期急速下降。主成分分析显示内源性脂肪水解酶对脂质的降解有一定的影响作用,对脂肪氧化的影响极小;LOX对脂肪降解的影响较小,与脂质的氧化正相关;多不饱和脂肪酸含量在腌制阶段和烘干阶段呈明显下降趋势(P0.05);单不饱和脂肪酸脂肪酸和饱和脂肪酸含量均在腌制阶段和烘干阶段显著增加(P0.05);二十碳五烯酸和二十二碳六烯酸两者的含量变化呈现出互补状态。     

红烧肉制作过程中脂肪氧化和脂肪酸组成的变化

脂肪氧化和脂肪酸组成变化对肉制品的营养和风味产生重要影响。研究红烧肉烹制全过程中原料、水焯后、炖煮1h、炖煮2h 4个关键工艺点中猪肉的基本物理化学指标、脂肪氧化和脂肪酸组成变化情况。结果表明：成品红烧肉水分含量和粗脂肪含量分别比原料肉下降18.17%和43.46%,烹饪损失率为25.04%;过氧化值(POV)在炖煮1h后达到峰值,随后又下降;硫代巴比妥酸值(TBA)在烹制过程中逐渐上升(P＜0.05);烹制过程使饱和脂肪酸(SFA)比例显著下降(P＜0.05),单不饱和脂肪酸(MUFA)比例显著上升(P＜0.05),不饱和脂肪酸与饱和脂肪酸比值(UFA/SFA)从1.38上升到2.34,提高了猪肉中油脂的营养价值。     

葱姜蒜混合物对炖煮猪肉感官品质、脂肪氧化及脂肪酸组成的影响

研究了不同添加量葱姜蒜混合物(onion-ginger-garlic,OGG)(5%、10%、15%)对炖煮猪肉感官品质(色泽、质地、滋味、香气)、基本理化指标(脂肪和水分)、脂肪氧化程度(过氧化值(POV)和硫代巴比妥酸值(TBA))及脂肪酸组成的影响。结果表明:OGG的添加能够提高炖煮猪肉的感官品质、改善肉的持水力,且随着OGG添加量的增大,炖煮猪肉的持水力显著提高(P0.05)。OGG能够抑制炖煮猪肉过氧化物及TBARS的产生,且添加量为15%的效果最显著(P0.05)。炖煮猪肉中添加OGG能显著抑制猪肉脂肪酸氧化,尤其是不饱和脂肪酸的氧化,且随着添加量的增加其抑制效果也明显提高。此外,OGG的添加还影响炖煮猪肉脂肪酸含量,添加OGG制得的炖煮猪肉,其单不饱和脂肪酸和多不饱和脂肪酸含量显著升高(P0.05),提高了不饱和脂肪酸(UFA)和饱和脂肪酸(SFA)的比例(P0.05),从而改善了猪肉的营养价值。     

Pastirma加工对马肉品质的影响

按照国家标准和气相色谱法对鲜马肉和Pastirma马肉的基本理化性质、剪切力和和脂肪酸进行测定和分析。结果发现:鲜马肉和Pastirma工艺制备的p H值没有显著性变化(P0.05),亮度值L显著降低,a值显著增加,水分含量显著减少,蛋白质含量显著增加(P0.05);马肉的嫩度在Pastirma的风干过程中显著降低(P0.05);马肉脂肪含量从高到低依次为:油酸(C18:1)、棕榈酸(C16:0)、亚油酸(C18:2)、棕榈油酸(C16:1)、硬脂酸(C18:0)、肉豆蔻酸(C14:0),鲜马肉不饱和脂肪酸含量较高,加工成pastirma后不饱和脂肪酸含量显著降低。     

泡酒肥肉浸制过程中脂肪氧化和脂肪酸组成的变化

泡酒肥肉是豉香型白酒(玉冰烧)生产过程"陈肉酝浸"工序中的关键元素,目前对泡酒肥肉在浸制过程中的变化尚不清楚。检测了泡酒肥肉浸制过程中的各阶段肥肉的脂肪氧化及脂肪酸含量的变化。结果表明,在浸制过程中,泡酒肥肉的酸价和硫代巴比妥酸值(TBARS)显著上升(p<0.05),总饱和脂肪酸(SFA)和总不饱和脂肪酸(UFA)含量均显著下降(p<0.05)。浸制后肥肉中的棕榈酸(C_16:0)、油酸(C_18:1)、硬脂酸(C_18:0)和亚油酸(C_18:2)等脂肪酸含量较高,且变化均显著(p<0.05);总饱和脂肪酸与总不饱和脂肪酸的比值(SFA/UFA)从1.83下降到1.38,变化显著(p<0.05),说明不饱和脂肪酸的比例升高,有利于后续豉香型白酒的陈肉酝浸过程中风味物质的生成。结果表明了泡酒肥肉浸制过程中脂肪氧化及脂肪酸的变化,将为建立泡酒肥肉质量标准提供科学依据。     

反复冻融对缠丝兔加工过程中脂肪酸含量变化的影响

以反复冻融兔肉为原料,分析缠丝兔加工过程中的脂肪酸含量变化。结果表明：与新鲜原料兔肉对照,随着冻融次数增加,反复冻融原料兔肉及其腌制后和烘烤后的脂肪含量显著降低,硫代巴比妥酸值显著增加（P＜0.05）;原料兔肉检测出棕榈酸（C16∶0）、亚油酸（C18∶2）等脂肪酸,在缠丝兔加工过程中,脂肪降解产生了油酸（C18∶1）;反复冻融兔肉在腌制和烘烤后的脂肪酸也呈显著性变化（P＜0.05）;5 次冻融原料的缠丝兔脂肪含量最低（0.023 8%）、硫代巴比妥酸值最高（0.216 8 mg/kg）。表明兔肉反复冻融对缠丝兔的脂肪酸含量影响显著。     

Effects of feeding micronised flaxseed on yield and composition of milk from Holstein cows

Nine multiparous Holstein cows were used in three 3 × 3 Latin squares to investigate the effects of feeding unheated and micronised flaxseed on milk yield and milk fatty acid composition. Three diets were formulated to meet the nutrient requirement of dairy cows in early lactation: a control diet with no added flaxseed (NFS), an unheated flaxseed diet (UFS) and a micronised flaxseed diet (MFS). The level of flaxseed in UFS and MFS was 70 g kg^?1 of the diet dry matter (DM). Feeding flaxseed to dairy cows had no effect on DM intake or milk yield. However, energy‐corrected milk was higher (P < 0.05) for cows fed MFS than for those fed UFS or NFS. Supplemental flaxseed reduced (P < 0.05) the milk fat percentage without affecting the concentration of milk protein or milk lactose. However, the yield of milk components was not affected by feeding flaxseed. The concentrations of short‐chain (C_4:0 to C_12:0) and medium‐chain (C_14:0 to C_17:0) fatty acids were decreased (P < 0.05) while those of long‐chain fatty acids (C_18:0 to C_18:3) were increased (P < 0.05) in the milk of cows fed UFS and MFS compared with cows fed NSF. Feeding flaxseed to dairy cows can alter the milk fatty acid composition, but only minor effects on milk fatty acid composition can be expected by feeding micronised versus unheated flaxseed. Copyright © 2003 Society of Chemical Industry     

Effect of pasture vs. concentrate feeding with or without antioxidants on carcass characteristics, fatty acid composition, and quality of Uruguayan beef

Thirty Hereford steers were finished either on pasture (n=10) or concentrate (n=20) to determine dietary and antioxidant treatment effects on carcass characteristics, fatty acid composition, and quality of Uruguayan beef. Half of the steers finished on concentrate were supplemented with 1000 I.U. vitamin E head(-1) day(-1) for 100 days. Postmortem vitamin C was added to ground beef (0.05% v/w) displayed for 8 days at 2?°C. Carcasses from steers finished on concentrate had greater (P<0.05) carcass weight, conformation, degree of finishing, fat depth, and ribeye area than pasture finished animals. Carcasses from pasture-fed steers showed darker (P<0.05) longissimus color and yellower (P<0.05) fat at 24 h postmortem than concentrate-fed. Initial longissimus Warner-Bratzler shear force (WBSF) values were similar (P>0.05) between pasture- and concentrate-fed animals. However, beef from pasture-fed cattle had lower (P<0.05) WBSF values at 7 and 14 days postmortem. Longissimus α-tocopherol concentrations were greater (P<0.01) for pasture- and concentrate-fed animals that were supplemented with vitamin E compared to concentrate-fed. Steaks from pasture-fed and vitamin E supplemented cattle had similar (P>0.05) TBARS values, which were lower (P<0.05) than steaks from concentrate-fed steers during 21 days of display. Ground beef from vitamin E supplemented steers had the lowest TBARS values; whereas samples from pasture-fed animals had the lowest lipid stability with higher TBARS levels than other treatments. Vitamin C addition to ground beef did not (P>0.05) reduce lipid oxidation. Vitamin E supplementation of concentrate-fed cattle had no effect (P>0.05) on color stability of ground beef or steaks. The a(?) (redness) and b(?) (yellowness) values were higher (P<0.05) when vitamin C was added to ground beef. Longissimus fatty acid content of concentrate-fed animals was twofold greater (P<0.01) than pasture-fed. The percentages of C14:0, C16:0, and C18:1 fatty acids were higher (P<0.01) in the intramuscular fat of concentrate-fed steers, whereas pasture-fed cattle showed greater (P<0.01) proportions of C18:0, C18:2, C18:3, C20:4, C20:5, and C22:5. Total conjugated linoleic acid (CLA) and CLA isomer c9t11 were higher (P<0.01) for pasture- than concentrate-fed cattle. Vitamin E supplementation of concentrate-fed steers increased lipid stability of ground beef and steaks, but was unable to improve color stability; whereas vitamin C addition to ground beef increased color stability without altering lipid oxidation. Finishing cattle on pasture enhanced the unsaturated fatty acid profile of intramuscular fat in beef including CLA and omega-3 fatty acids.     

Incorporation of by-products of rosemary and thyme in the diet of ewes: effect on the fatty acid profile of lamb

The present study measured changes in fatty acid composition of lamb meat from sheep fed plant by-products (rosemary- and thyme-distilled leaves) during pregnancy and lactation. For that, thirty-six pregnant Segureña ewes were employed per experiment (2 experiments in total: A with distilled rosemary leaf—DRL—and B with distilled thyme leaf—DTL) and were randomly assigned into three homogeneous groups. Sheep in the control group (C _R: control DRL experiment; C _T: control DTL experiment) were given a basal diet (BD). The experimental diets of the other two groups were modified by substituting 10 and 20 % of the BD by DRL (R ₁, R ₂) in experiment A and with 10 and 20 % of the BD by DTL (T ₁, T ₂) in experiment B. Moisture, fat, protein content, fatty acid profile, and pH of the fresh lamb meat were analysed. Pearson’s correlations were made between fatty acid profile and rancid odour (RO), TBARS of fresh lamb meat at day 21 of storage. The incorporation of thyme- and rosemary-distilled leaves in the diet of pregnant and lactating ewes caused a significant increase (P < 0.05) in the levels of polyunsaturated fatty acid (PUFA), unsaturated fatty acids (UFA), and a significant decrease in the percentage of saturated fatty acid (SFA) saturation index (S/P), atherogenic (AI), and thrombogenic (TI) indices in lamb meat. In general, this effect was more pronounced with a diet of 20 % DRL. High positive correlations were found between rancid odour and SFA (except C _18:0 and C _20:0) and monounsaturated fat (MUFA); on the contrary, a negative correlation was shown between PUFA content and RO, TBARS. Thus, adding by-products of rosemary and thyme to the diet of ewes significantly improved fatty acid profile of lamb meat.     

Changes in lipid profiles and volatile compounds of shrimp (Penaeus vannamei) submitted to different cooking methods

Herein, the effect of three common cooking methods (boiling, baking and microwaving) on lipids and volatile compounds in shrimp (Penaeus vannamei) was assessed. The results revealed that contents of phospholipid, triglyceride, cholesterol and free fatty acids in the cooked shrimp significantly declined when compared to the raw shrimp. And these decreases occurred especially in the boiling and microwaving treatment. Among free fatty acids, the contents of palmitic acid (C_16:0), oleic acid (C_18:1n9c) and linoleic acid (C_18:2n6c) also decreased greatly in the boiled and microwaved shrimp, while EPA and DHA enhanced in each cooked group (P < 0.05). Furthermore, microwaved samples exhibited higher levels of oxidation parameters, such as acid value (AV) and thiobarbituric acid-reactive substances (TBARS). For volatile compounds, a total of 31 volatile compounds were detected by GC-IMS, and these contents increased after cooking. Aliphatic volatile compounds, including 1-octen-3-one, pentane-1-ol, 1-propanol, octanal, heptanal, pentanal and hexanal, were main flavour contributors in cooked shrimp, with higher contents observed in microwaved shrimp. In addition, the correlation analysis showed that linoleic acid was a substrate for 15 volatile compounds of cooked shrimp meat. These results indicate that microwave cooking exerts more influences on lipid profiles in shrimp and consequently caused more volatile compounds.     

Changes on physico-chemical,textural, lipolysis and volatile compounds during the manufacture of dry-cured foal “cecina”

The changes in the physico-chemical and textural properties, lipolysis and volatile compounds during the manufacture of dry-cured foal “cecina” were studied. The pH increased during the last stages of processing but gradually declined over the curing period. TBARS values, hardness and chewiness increased with processing time from 0.14, 2.74 and 0.83 to 3.49 mg malonaldehyde/kg, 20.33 kg and 5.05 kg ∗ mm, respectively. Ripening time also affected the colour parameters: lightness (L*), redness (a*) and yellowness (b*) (P < 0.001). The total average content of free fatty acid (FFA) increased significantly from 433.7 mg/100 g of fat in the raw pieces to 2655.5 mg/100 g of fat at the end of the drying–ripening stage. The main FFA at the end of the manufacturing process was palmitic acid (C_16:0), followed by oleic (C_18:1cis9), stearic (C_18:0) and linoleic (C_{18:2n − 6}). A total of fifty five volatile compounds were identified during the manufacture of dry-cured foal “cecina”, including esters, aldehydes, aliphatic hydrocarbons, branched hydrocarbons, alcohols, aromatic hydrocarbons, furans, ketones. Aldehydes reached their maximum level at the end of the post-salting stage. In the final product, esters became the dominant chemical compounds.