Dietary influence on the m. longissimus dorsi fatty acid composition of lambs in relation to protein source

Dietary lipid effect, as a consequence of protein supplement, on lamb m. longissimus dorsi fatty acid composition was investigated, with emphasis on biohydrogenation intermediates. Crossbred lambs (White Swedish Landrace × Texel) were fed a barley-based diet without (CON) or with protein supplements including peas (PEA), rapeseed cake (RC) or hempseed cake (HC). The HC diet resulted in the highest muscle 22:6n-3 proportion, with the RC diet being similar (P<0.05). Protein supplement did not affect the c9,t11 conjugated linoleic acid (CLA) proportion, however the HC diet increased some minor CLA isomers, including t10,c12 CLA (P<0.05). The t10-18:1 and total trans-18:1 were lowest for the RC diet (P<0.05), likely relating to rumen conditions and precursor availability. The saturated, monounsaturated and branched-chain fatty acids were largely unaffected by protein supplement. In conclusion, feeding the RC diet lowered the t10-18:1 and total trans-18:1 in meat, and modestly increased 22:6n-3 content. The direction of these changes would be beneficial, making the RC diet the preferred protein supplement; however the magnitude of the changes in the present experiment may not be sufficient to have an impact on human health.     

Dietary manipulation of fatty acid composition in lamb meat and its effect on the volatile aroma compounds of grilled lamb

The effect on lamb muscle of five dietary supplements high in polyunsaturated fatty acids (PUFA) was measured. The supplements were linseed oil, fish oil, protected lipid (high in linoleic acid (C18:2 n-6) and α-linolenic acid (C18:3 n-3)), fish oil/marine algae (1:1), and protected lipid/marine algae (1:1). Eicosapentaenoic acid (C20:5 n-3) and docosahexaenoic acid (C22:6 n-3) were found in the highest amounts in the meat from lambs fed diets containing algae. Meat from lambs fed protected lipid had the highest levels of C18:2 n-6 and C18:3 n-3, due to the effectiveness of the protection system. In grilled meat from these animals, volatile compounds derived from n-3 fatty acids were highest in the meat from the lambs fed the fish oil/algae diet, whereas compounds derived from n-6 fatty acids were highest in the meat from the lambs fed the protected lipid diet.     

Lamb meat quality as affected by a natural or artificial milk feeding regime

Fourteen Barbaresca lambs were divided into two groups of seven at 24h from birth and reared exclusively on natural milk (NR) or on artificial milk (AR). Lambs were slaughtered at 40 days of age. The NR group tended (P<0.10) to grow faster, thus resulting in a higher (P<0.10) carcass weight as compared to the AR group. AR meat was darker (P<0.05), leaner (P<0.001) and with a higher moisture (P<0.10) and ash (P<0.05) content than its counterpart. The proportion of polyunsaturated fatty acids was higher (P<0.01), while that of saturated lower (P<0.01) in meat from the AR group, resulting in a higher (P<0.01) polyunsaturated/saturated ratio. Linoleic acid content (P<0.001) and its n-6 series derivatives, except 9-12 trans C18:2 n-6 (P<0.001), increased more in the AR group meat than in the NR group. On the other hand, α-linolenic (P<0.001) and other n-3 series fatty acids were higher in meat from the NR group than in the AR group, leading to a lower (P<0.001) n-6/n-3 ratio. Furthermore, 9 cis 11 trans CLA was higher (P<0.001) in NR meat compared to AR meat. Finally, a milk-feeding regime exclusively based on artificial milk adversely affected the dietetic value of lamb meat compared to a natural rearing system, reducing the level of desirable fatty acids such as n-3 series and CLA.     

澳洲美利奴羊肉脂肪酸组成

选择3 只澳洲美利奴羔羊的背最长肌、臀肌及臂三头肌,利用气相色谱-质谱联用技术对其脂肪酸含量进行测定及分类探讨。结果表明：澳洲美利奴羊肉中共含有脂肪酸35 种,其中C15:1、C16:0、C17:1、C18:0、C18:1 n-9c脂肪酸含量较高,3 个部位肌肉中：不饱和脂肪酸含量＞饱和脂肪酸含量＞单不饱和脂肪酸含量＞多不饱和脂肪酸含量,且每个部位肌肉中单不饱和脂肪酸含量比多不饱和脂肪酸含量均高出2～3 倍;n-3脂肪酸亚麻酸甲酯（C18:3 n-3）在臂三头肌中的含量显著高于背最长肌（P＜0.05）;与另外2 个部位相比,臂三头肌总脂肪酸、饱和脂肪酸、不饱和脂肪酸、中链脂肪酸及长链脂肪酸含量均最高;臂三头肌中多不饱和脂肪酸与饱和脂肪酸含量比值最高,背最长肌中最低。     

Influence of stall finishing duration of Italian Merino lambs raised on pasture on intramuscular fatty acid composition

Forty male Italian Merino lambs were used to study the effects of four feeding systems on muscle fatty acids composition: S group-ten lambs were kept indoors, and fed with concentrate for all experimental period (89 days); P group-ten lambs were allowed to graze a pasture for all experimental period; PS37 group-ten lambs were allowed to graze a pasture for 52 days and shifted indoor, fed with concentrate, 37 days before slaughtered; PS14 group, where 10 lambs were fed on pasture for 75 days and shifted indoor, fed with concentrate, 14 days before slaughtered. Grazing lowered the levels of C12:0, C14:0, C16:0 and n-6 PUFA and increased n-3 PUFA and CLA isomer compared to concentrate feeding. After a short period of indoor finishing with concentrate, the fatty acid characteristics of the meat retain a part of the benefits occurring from grazing, while a longer period seems to erase almost all the benefits from grazing.     

The effect of spineless cactus (Opuntia ficus-indica f. inermis) supplementation on growth, carcass, meat quality and fatty acid composition of male goat kids

Lambs from two Turkish breeds, Kivircik a meat breed and Sakiz a breed used for milk and meat production, were fed a diet containing commercial concentrate and hay in the ratios of either 75:25 or 25:75. The effects on fatty acid composition were studied. After weaning (at about 8 weeks) a total of 40 male lambs (20 Kivircik, 20 Sakiz) were divided into four groups of 10 animals and fed either commercial concentrate or grass hay-based diets. The lambs were group fed indoors for 60 days. The mean intramuscular total fatty acid content of longissimus dorsi for Sakiz was lower than that for Kivircik lamb. Increasing the dried grass percentage in the ration decreased the final live weight of the lambs but intramuscular total fatty acid content increased (2088 vs. 1791mg/kg muscle, p<0.001). All n-3 polyunsaturated fatty acids were higher in muscle from lamb fed dried grass-based diets than from lambs fed concentrate-based diets whereas all n-6 were higher in the latter. Polyunsaturated:saturated ratios were higher in the latter animals; 0.26 compared with 0.16 in the lambs fed grass hay. Concentrate groups displayed a higher n-6/n-3 ratio in the same muscle, 7.11 compared with 1.28 in the lambs fed grass. Muscle from Kivircik lambs had higher concentrations of C18:2 n-6 and its metabolite C20:4 n-6 (p<0.001) and also C18:3 n-3.     

Effect of oil sources and vitamin E levels in the diet on the composition of fatty acids in rooster thigh and chest meat

The aim of this study was to evaluate the inclusion of different oil sources and dietary supplementation with vitamin E on the composition of fatty acids in rooster meat. Two hundred and forty 30‐week‐old White Leghorn roosters were distributed in a completely randomized factorial arrangement of 5 × 2, using five oil sources (sunflower, soybean, canola, linseed and fish) and two levels of antioxidant (30 and 400 mg vitamin E kg^?1 of diet). The intake of fish and canola oil in the diet reduced (P < 0.05) the content of saturated and unsaturated fatty acids in the thigh meat. Amongst the unsaturated fatty acids in the thigh, the fish and canola oil reduced (P < 0.05) the level of ω6 fatty acid, with a consequent decrease in the ratio ω6:ω3. The diet with fish oil increased (P < 0.05) the content of C22:6ω3 in the thigh meat. The use of linseed oil resulted in a significant reduction of the ratio of ω6:ω3 fatty acid in the thigh. The use of soybean oil in the diet increased (P < 0.05) the content of saturated and unsaturated fatty acids in the thigh, specifically in the content of ω6. The inclusion of vitamin E increased the polyunsaturated fatty acids in the chest meat, such as C18:3ω3, C20:5ω3 and C22:6ω3. Copyright © 2004 Society of Chemical Industry     

内蒙古放牧和舍饲绵羊肉的脂肪酸特征

内蒙古盛产天然放牧牛羊肉,规模化舍饲也在农区和禁牧地区迅速发展,但不同饲养方式绵羊肉的脂肪酸特征缺乏系统评价。从内蒙古东北部、东中部和西部3 个典型纯牧业和农牧业区的7 个旗县采集草原放牧绵羊肉109 份和舍饲绵羊肉30 份,采用气相色谱法测定脂肪酸并进行主成分分析（principal component analysis,PCA）和描述性统计。结果表明：对各旗县绵羊肉样按放牧和舍饲2 种饲养方式或地域聚类进行PCA,呼伦贝尔和锡林郭勒草原放牧肉样聚集在一起,巴彦淖尔农区舍饲肉单独聚类,放牧和舍饲同地域内各旗县和品种聚类均未能分离;股二头肌和羊肥尾多数脂肪酸含量存在差异,但放牧和舍饲肉样间特征脂肪酸有一致性;羊肥尾脂肪酸对2 种饲养方式的区分效果比股二头肌好;放牧肉n-3多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）、α-C18:3 n-3（α-亚麻酸）、C14:1和C14:0含量显著高于舍饲肉,放牧股二头肌和羊肥尾n-3 PUFA含量为舍饲的6.0 倍和4.2 倍,而α-亚麻酸含量为舍饲的4.6 倍和3.9 倍,舍饲绵羊肉n-6 PUFA、反式脂肪酸和C18:2 n-6c（亚油酸）、C18:1 n-9t（反式油酸）含量显著高于放牧肉。     

苏尼特羊和小尾寒羊的屠宰性能、肉品质、脂肪酸和挥发性风味物质比较

选择5月龄苏尼特羊、小尾寒羊各10?只,测定其屠宰性能,再分别取背最长肌测肉品质、脂肪酸含量以及挥发性成分并进行比较。结果表明：苏尼特羊的净肉率和肉骨比显著大于小尾寒羊（P＜0.05）。苏尼特羊的色泽（a*、b*）、嫩度优于小尾寒羊（P＜0.05）,熟肉率和pH值没有显著差异;从脂肪酸含量分析发现,苏尼特羊肉中饱和脂肪酸与多不饱和脂肪酸含量均高于小尾寒羊,其中C16:0和C18:0含量显著高于小尾寒羊（P＜0.05）,但含量比较丰富的不饱和脂肪酸（C18:1、C18:2n6c和C20:4n6）在2?种羊之间没有显著差异（P＞0.05）。羊肉的挥发性成分主要由羰基化合物和醇类化合物组成,不同品种对挥发性成分的相对含量和构成影响很大,苏尼特羊的醛类和酮类化合物含量高于小尾寒羊,但醇类化合物含量低于小尾寒羊,筛选主要风味化合物为己醛、辛醛、壬醛、1-辛烯-3-醇和2,3-辛二酮。     

Comprehensive analysis of fatty acids in human milk of four Asian countries

Human milk lipids provide not only energy but also indispensable bioactive components such as essential fatty acids. To establish the recommended daily intake value and guidelines for infant formula, a reference library of fatty acid composition has been generated from 4 Asian countries (South Korea, China, Vietnam, and Pakistan). Regardless of country, palmitic acid (C16:0), linoleic acid (C18:1), and linolenic acid (C18:2) were the 3 most abundant fatty acids in human milk and account for more than 75% of total fatty acids (total FA). However, there were several considerable differences between fatty acids, particularly n-3 and n-6 (omega-3 and omega-6) groups. Chinese mothers' milk had a high concentration of linoleic acid at 24.38 ± 10.02% of total FA, which may be due to maternal diet. Among the 4 countries, Pakistani mothers' milk contained a high amount of saturated fatty acid (56.83 ± 5.96% of total FA), and consequently, polyunsaturated fatty acids, including n-3 and n-6, were significantly lower than in other countries. It is noteworthy that docosahexaenoic acid (DHA) in Pakistani mothers' milk was 44.8 ± 33.3 mg/L, which is only 25 to 30% of the levels in the other 3 countries, suggesting the need for DHA supplementation for infants in Pakistan. Moreover, the ratio of n-6 to n-3 was also remarkably high in Pakistani mothers' milk (15.21 ± 4.96), being 1.4- to 1.7-fold higher than in other countries. The average DHA:ARA ratio in Asian human milk was 1.01 ± 0.79. Korean mothers' milk showed a high DHA:ARA ratio, with a value of 1.30 ± 0.98, but Pakistani mothers' milk had a significantly lower value (0.42 ± 0.12). The fatty acid compositions and anthropometric data of mother (body mass index, age) did not show any correlation. The obtained data might provide information about human milk compositions in the Asian region that could benefit from setting up recommended nutrient intake and infant formula for Asian babies.     

Effect of grass or concentrate feeding systems and rate of growth on triglyceride and phospholipid and their fatty acids in the M. longissimus thoracis of lambs

Thirty-two male Ile-de-France lambs were used in a factorial 2×2 design to analyse the effects of feeding systems (grass outdoor, G, or concentrate and hay indoor: stall, S) and of growth rate (low, L, or high, H) on total lipids, triglyceride (TG) and phospholipid (PL) contents and their fatty acid composition in the longissimus thoracis muscle (L.T.). Contents were lower for TG (10.4 vs. 15.8 mg/100 g fresh tissue, P<0.05) and higher for PL (6.4 vs. 5.8 mg/100 g fresh tissue, P <0.05) in grass-fed lambs compared to stall-fed ones. TG of grass fed lambs displayed lower proportions of palmitic acid (C16:0), monounsaturated fatty acids (MUFAs), linoleic acid (C18:2n-6) and other (n-6) polyunsaturated fatty acids (PUFA) and higher proportions of stearic acid (C18:0), linolenic acid (C18:3n-3), cis 9, 11 trans C18:2 and trans monounsaturated fatty acids. In PL of the same lambs only lower MUFA, C18:2n-6 and (n-6) PUFA and higher C18:3n-3, (n-3) PUFA and cis 9, 11 trans C18:2 were observed. Growth rate had no effect on lipid, TG or PL contents of longissimus thoracis. However C18:0 proportions were higher in TG and lower in PL for low growth rate lambs. Low growth rate lambs had also lower cis 9, 11 trans C18:2 in TG. Thus, irrespective of growth rate, the muscle lipids characteristic of grass fed lambs fulfilled the recommended features of human food components much better than that of stall fed lambs, namely for CLA and C18:3n-3. The lower ratios of (n-6) to (n-3) PUFA displayed in grass fed lambs both in TG and in PL were also useful to discriminate all the grass fed lambs from all the stall fed animals.     

Influence of ewe feeding systems on fatty acid composition of suckling lambs

The main objective of this study was to evaluate the effects of ewe dietary treatments on the intramuscular fatty acid composition of suckling lambs. Twenty-four pregnant Italian Merino ewes were divided into two equal groups. One group (pasture-fed group) was allowed to graze a natural pasture and the other group (stall-fed group) was penned indoors and fed with hay and concentrate. After lambing, all ewes stayed with their respective lambs for the whole experimental period. Lambs were slaughtered at 100 days of age with an average live weight of 20kg. Fatty acid profiles of milk and lamb meat (longissimus lumborum muscle) were analysed. Intramuscular fat from pasture-fed lambs showed higher (P<0.001) proportions of polyunsaturated fatty acids. The percentage of lauric (C12:0; P<0.05), palmitic (C16.0; P<0.001) and oleic (C18.1; P<0.001) fatty acids were higher in the intramuscular fat from stall-fed lambs, whereas pasture-fed lambs showed greater proportions of linolenic (C18:3; P<0.001), eicosapentaenoic (C20:5; P<0.001) and docosapentaenoic (C22:5; P<0.05) fatty acids. Moreover, the intramuscular fat from pasture-fed lambs displayed a higher (P<0.001) PUFA/SFA ratio, and a lower (p<0.001) n-6/n-3 ratio. The conjugated linoleic acid (CLA) tended to be higher (P=0.07) in the intramuscular fat from pasture-fed lambs. This study confirmed that pasture enhanced the unsaturated fatty acid profile of intramuscular fat in lambs including n-3 fatty acids.     

Endogenous production of n-3 and n-6 fatty acids in mammalian cells

Polyunsaturated fatty acids (PUFA) are important components of mammalian diets, and the beneficial effects of n-3 PUFA on human development and cardiovascular health have been well documented. Caenorhabditis elegans is one of the few animals known to be able to produce linoleic (LA, 18:2n-6) and alpha-linolenic (ALA, 18:3n-3) essential fatty acids. These essential PUFA are generated by the action of desaturases that successively direct the conversion of monounsaturated fatty acids (MUFA) to PUFA. The cDNA coding sequences of the C. elegans Delta(12) and n-3 fatty acid desaturases were each placed under the control of separate constitutive eukaryotic promoters and simultaneously introduced into HC11 mouse mammary epithelial cells by adenoviral transduction. Phospholipids from transduced cells showed a significant decrease in the ratios of both MUFA:PUFA and n-6:n-3 fatty acids relative to control cultures. The fatty acid profile of transduced cellular phospholipids revealed significant decreases in MUFA and arachidonic acid (20:4n-6), and increases in LA, ALA, and eicosapentaenoic acid (20:5n-3). The fatty acid composition of triacylglycerols derived from transduced cells was similarly, but less dramatically, affected. These results demonstrate the functionality of C. elegans fatty acid desaturase enzymes in mammalian cells. Expression of these desaturases in livestock might act to counterbalance the saturating effect that rumen microbial biohydrogenation has on the fatty acid profile of ruminant products, and allow for the development of novel, land-based dietary sources of n-3 PUFA.     

脂肪酸鉴定及其在牦牛乳、牦牛肉品质分析中的应用

利用气相色谱-质谱对不同来源的牦牛乳、犏牛乳和牦牛肉脂肪酸组成及含量进行检测,以功能性脂肪酸含量为指标对牦牛乳和牦牛肉的品质进行评价。结果表明:牦牛乳、犏牛乳和牦牛肉中分别鉴定出47、46、37种脂肪酸;不同月份、海拔的牦牛乳中BCFA含量和n-6/n-3比值整体差异极显著(P <0.001),对比发现8月份采自3 500 m夏季牧场的牦牛乳品质最优;犏牛乳中富含多种功能性脂肪酸,接近牦牛乳脂肪酸组成;两种饲养方式(放牧和舍饲育肥)牦牛肉中功能性脂肪酸含量和n-6/n-3比值差异显著,放牧牦牛肉中DHA、DPA、EPA、BCFA等功能性脂肪酸含量均显著高于舍饲育肥牦牛肉,相较于舍饲育肥牦牛,放牧牦牛的牦牛肉品质更佳。     

LIPID CHARACTERISTICS OF EMU MEAT AND TISSUES

Twenty four (24) samples of emu meat (drumstick) and fat (abdominal fat (AF) and back fat (BF)), liver and heart tissue were collected from three (3) farms, and twelve (12) samples of chicken (drumstick) and beef (steak) were collected from supermarkets. The AF and BF of emu contained over 99% triacylglycerols. Monounsaturatedfatty acids (MUFA) constituted to 56% in AF and BF, saturated fatty acids (SAFA) at 31% and polyunsaturated fatty acids (PUFA) constituted to 13%. Oleic acid (C18:1n-9) was the predominant MUFA at 48%. The emu leg meat total lipids were up to 3%. Phospholipid constituted the major lipid class in emu and chicken meat at 64%, higher (P<0.05) than beef meat (47%). The emu drumstick contained higher (P<0.05) linoleic (C18:2n-6), arachidonic (C20:4 n-6), linolenic (C18:3 n-3) and docosahexaenoic (C22:6 n-3) acids than chicken drumstick and beef steak. The ratio of polyunsaturated fatty acids to saturated fatty acids in emu meat was 0.72, higher (P<0.0001) than chicken meat, 0.57 and beef meat, 0.3. The ratio of n-6 to n-3 fatty acids did not differ (P>0.05) among the three sources of meat.     

Effect of different feeds on meat quality and fatty acid composition of lambs fattened at pasture

Two kinds of feed (commercial concentrate vs whole supplemented barley) were compared in unweaned lambs and lambs weaned at 40 days of age, fattened at pasture and slaughtered at 28 kg live weight, in order to observe their effects on meat quality and fatty acid composition. The weaning status influenced fatness; unweaned lambs displayed a greater carcass fatness score and more kidney knob and channel fat than weaned lambs. Compared with the unweaned animals, weaned lambs exhibited higher pH values at 0 h and 45 min in the m. longissimus thoracis (LT) and at 45 min and 24 h in the m. semitendinosus. The redness index (a*) of the m. LT of weaned lambs was higher than that of unweaned lambs, and lambs fed concentrate displayed a higher yellowness index (b*) and a higher Hue value than those given whole barley. Water-holding capacity did not vary with the treatments studied. The proportion of saturated fatty acids (SFA) in intramuscular fat was higher (P?0.001) in unweaned lambs than in weaned ones while, on the other hand, the latter displayed a higher proportion of monounsaturated fatty acids (MUFA) and a higher n-6/n-3 ratio in the same tissue. As was the case with intramuscular fat, the subcutaneous fat of unweaned lambs exhibited higher proportions of medium-chain fatty acids (C12:0, C14:0 y C16:0) and lower ones of stearic (C18:0) and oleic (C18:1) fatty acids than that of weaned lambs. Higher levels of heptadecenoic acid (C17:1) were found in the subcutaneous fat of lambs fed whole barley than in that of lambs given concentrate. PUFA/SFA and n-6/n-3 ratios were lower in the m. LT than in the m. quadriceps femoris.     

Conjugated linoleic acid (CLA) and polyunsaturated fatty acids in muscle lipids of lambs from the Patagonian area of Argentina

The concentrations of fatty acids were measured in total lipids, triacyglycerol and phospholipid fractions of intramuscular fat (IMF) from the Longissimus dorsi (LD) muscle of 10 lambs reared to approximately 30kg live weight on natural pasture with their dams. Fatty acid composition was also measured in 25 (five of each) Semitendinosus (ST), Semimembranosus (SM), Rectus femoris (RF), Gluteus (GLU) and Tensor fascia latea (TFL) muscles. Intramuscular fat percentages were similar for all muscles. Aspects of the fatty-acid patterns of relevance to human nutrition tended to favor the leg muscles with lower saturated fatty acids (SFA %), n-6/n-3 fatty acid ratios (p<0.01) and higher concentrations of the conjugated linoleic acid (CLA) (p<0.05). The estimated fatty acid concentrations (mg/100g of meat) showed higher contribution of arachidonic (C20:4 n-6), eicosapentanoic (C20:5 n-3), docosapentanoic (C22:5 n-3) and docosahexanoic (C22:6 n-3) acids in leg compared to LD lipids.     

Significance of fat supplemented diets on pork quality - Connections between specific fatty acids and sensory attributes of pork

The influence of two diets with different fatty acid compositions has been studied with regard to overall pork quality and significance of specific fatty acids on sensory attributes in fried chops and oven roasts. Twenty castrates and 20 females were in a balanced experimental set-up fed with a standard diet supplemented with α-tocopherol (200mg/kg feed) where the fat source was either 3% of palm oil or 3% rapeseed oil. After slaughter, despite differences in lipid composition and sensory attributes, no significant difference in overall meat quality parameters and flavour precursors was found. Comparison of the two diets showed that supplementation with rapeseed oil resulted in a significantly higher content of C18:3n-3 (polar lipid (PL), neutral lipid (NL)), C18:2n-6c (NL) and C20:2 (NL) in LD and C18:1n-9c, C18:2n-6c, C18:3n-3, C20:3n-3, C22:5n-3 in backfat, while supplementation with palm oil resulted in a higher content of C16:0 (NL), C16:1 (PL), C18:1n-9t (NL) in LD and C16:0, C17:0, C18:0, C16:1, C20:4n-6 in backfat. A positive and significant correlation between the contents of C18:2n-6c, C20:3n-6 in the PL fraction and the sensory attributes fried meat odour and sweet odour were found in fried pork chops from female pigs. Likewise, positive correlations were seen between the content of C18:1n-9c in the PL fraction and sensory attributes such as sourish odour, piggy odour and piggy flavour in whole oven roasts. These data substantiate the view that specific fatty acids in the PL fraction influences flavour attributes in pork.     

Fatty acid composition of meat from typical lamb production systems of Spain, United Kingdom, Germany and Uruguay

The fatty acid composition of commercial lambs from different production systems of Spain, Germany, United Kingdom and of two types of Uruguayan lambs (heavy and light) was studied. Concentrate fed lambs, as Spanish lambs, displayed the highest proportions of linoleic acid (C18:2), while Uruguayan lambs, reared under extensive grazing conditions, showed the highest proportions of linolenic acid (C18:3), due to the great concentration of this fatty acid in grass. German and British lambs, which were fed grass and concentrate, displayed intermediate proportions of linolenic acid (C18:3). Heavy Uruguayan lambs had higher intramuscular fat content (5.92%) than German (4.25%) and British (4.32%) lambs, and this content was twofold higher than light lambs (Spanish (2.41%) and light Uruguayan (3.05%)). Heavy Uruguayan, German and British lambs had a low polyunsaturated/saturated (P/S) ratio due to their high saturated fatty acid (SFA) content and proportion. Principal component analysis was performed to study the relationship between fatty acids. Spanish lambs were clearly separated from the other types and were situated close to the proportions of short chain and n-6 fatty acids and n-6/n-3 ratio in the data plot for fatty acid proportions. Light Uruguayan lambs were located close to long chain fatty acids, and heavy Uruguayan and British lambs were placed near the antithrombotic potential (ATT), stearic acid (C18:0), SFA and conjugated linoleic acid (CLA) proportions. German lambs were located between Spanish lambs and the other types.     

杀菌温度对乳化肠中脂肪酸组成和脂肪氧化的影响

通过氯仿-甲醇法提取乳化肠中的脂肪,并进行皂化和甲酯化,采用气相色谱-质谱联用技术系统对比研究 不同杀菌温度对乳化肠中脂肪酸组成和脂肪氧化的影响。结果表明：乳化肠经不同杀菌温度处理后,脂肪酸含量和 脂肪氧化都会发生一定程度的变化。杀菌温度超过100 ℃时,饱和脂肪酸（saturated fatty acids,SFA）含量显著增 加（P＜0.05）,而不饱和脂肪酸（unsaturated fatty acids,UFA）含量显著降低（P＜0.05）,其中多不饱和脂肪酸 （polyunsaturated fatty acid,PUFA）的含量呈极显著降低（P＜0.01）,而单不饱和脂肪酸（monounsaturated fatty acid,MUFA）含量差异不显著（P＞0.05）;n-6 PUFA/n-3 PUFA比值显著增加,PUFA/SFA比值显著降低,同时 100～110 ℃杀菌温度显著提高了产品的过氧化值（peroxide value,POV）和硫代巴比妥酸反应物（thiobarbituric acid reactive substances,TBARS）含量。100 ℃以上的杀菌温度使C14:0、C16:0、C18:0和C20:0的含量显著提高,同时 C18:2n6、C18:3n3、C20:3n6和C20:4n6的含量显著降低,而C20:5n3和C22:6n3未检出。结论：低于100 ℃的杀菌条件可以最大程度 保持产品原有的脂肪酸组成,而高于100 ℃的杀菌温度对产品的脂肪酸比例破坏明显,且可显著促进脂肪氧化,这 为杀菌条件在肉制品中的精细化调控提供技术支持。