The labile lipid fraction of meat: from perceived disease and waste to health and opportunity

The fatty acid composition of beef and pork has been stigmatized due to their relationships with several diseases from cardiovascular disease to cancer. Meat lipids are, however, one of the few components of meat that can be modified in content and composition, and can present opportunities for value added production and health promotion. Until regulations and policies are in place to define requirements for fatty acid enrichment, however, the process remains relatively academic. Once practical goals are in place for fatty acid enrichment in meat, both theory and practice need to converge for successful production of fatty acid enriched meat. The present review covers aspects of policy in Canada, and requirements for research networks to respond to theoretical and practical challenges associated with production of fatty acid enriched meat. Finally, needs for education and marketing are outlined which must be in place to truly realize a transition of meat lipids from perceived disease and waste to health and opportunity.     

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.     

Seasonal changes and muscle type effect on the nutritional quality of intramuscular fat in Mirandesa-PDO veal

The influence of slaughter season and muscle type on the detailed fatty acid composition, including conjugated linoleic acid isomers, and contents of total cholesterol and lipid-soluble antioxidant vitamins (α-tocopherol and β-carotene) in Mirandesa-PDO veal was assessed. Mirandesa purebred calves (n = 29) were raised in a traditional production semi-extensive system, slaughtered in late spring (June) or early autumn (October) and the longissimus lumborum and semitendinosus muscles were sampled for analysis. Although the lipid composition of PDO veal was only slightly affected by the slaughter season, it was markedly changed by the muscle type. However, PDO veal had values of pasture-fed cattle for lipid grass intake indicators, in both seasons and muscles. From a human health standpoint, intramuscular fat in Mirandesa-PDO veal has a high nutritional value throughout the year, with favorable ratios of n− 6/n− 3 and contents of n− 3 PUFA and α-tocopherol, as a result of the beneficial effects of grass feeding.     

GC-MS测定人乳及动物乳中支链脂肪酸组成

支链脂肪酸（BCFA）是乳中微量但对婴幼儿的生长发育具有重要意义的生物活性成分。利用GC-MS对人乳和4种动物乳（牛乳、羊乳、牦牛乳、骆驼乳）中BCFA种类及含量进行测定。结果表明：5种乳中共有64种脂肪酸,其中含15种BCFA,17种饱和脂肪酸（SFA）,18种单不饱和脂肪酸（MUFA）和14种多不饱和脂肪酸（PUFA）;BCFA含量呈现出很大的物种间差异,动物乳中的支链脂肪酸含量显著高于人乳（p<0.001）,牛乳、牦牛乳、羊乳、骆驼乳和人乳中BCFA多为异构（iso）和反异构（anteiso）BCFA,含量分别为2.82%、4.90%、3.35%、8.00%和0.28%;人乳中BCFA受孕龄影响显著（p<0.01）,足月儿乳母的母乳中含有丰富的BCFA。     

Effects of feeding flaxseed or sunflower-seed in high-forage diets on beef production,quality and fatty acid composition

Yearling steers were fed 70:30 forage:concentrate diets for 205 d, with either grass hay (GH) or red clover silage (RC) as the forage source, and concentrates containing either sunflower-seed (SS) or flaxseed (FS), each providing 5.4% oil to diets. Feeding diets containing SS versus FS significantly improved growth and carcass attributes (P < 0.05), significantly reduced meat off-flavor intensity (P < 0.05), and significantly increased intramuscular proportions of vaccenic (t11-18:1), rumenic (c9,t11-CLA) and n − 6 fatty acids (FA, P < 0.05). Feeding diets containing FS versus SS produced significantly darker and redder meat with greater proportions of atypical dienes (P < 0.05). A significant forage × oilseed type interaction (P < 0.05) was found for n − 3 FA, α-linolenic acid, and conjugated linolenic acid, with their greatest intramuscular proportions found when feeding the RC-FS diet. Feeding GH versus RC also significantly improved growth and carcass attributes, sensory tenderness (P < 0.05) and significantly influenced intramuscular FA composition (P < 0.05), but overall, forage effects on FA profiles were limited compared to effects of oilseed.     

Changes in lipolysis and volatile fraction of a goat cheese manufactured employing a hygienized rennet paste and a defined strain starter

The effect of a hygienized rennet paste (HRP) and a defined strain starter IFPL on the volatile fraction of goat cheese (Majorero) was examined. Three batches were made and those cheeses produced either industrially (IL) or in artisanal manner (AL) were compared with the experimental lot (EL), which included both HRP and IFPL starter in its manufacture. Analysis of the volatile fraction was by static headspace connected to GC–MS and this disclosed a total of 28 components belonging to the following chemical families: fatty acids, esters, ketones, aldehydes and alcohols. Most of the volatile components identified appeared in all lots but at different concentrations. IL cheeses were distinguished from the other lots, including HRP in their manufacture, essentially by a lower presence of esters and FFA (both branched-chain and aliphatic acids). The use of HRP and a defined strain starter culture (including Lb. casei IFPL 731 as adjunct) directly affected lipolysis degree. This was reflected in an increase in the mono-and diglyceride concentrations and in a greater content of short-chain FFA, particularly butanoic acid, an important flavour component, which imparts a desirable sharp, “piquant” taste to Majorero cheese. The IFPL starter culture also had a significant effect on concentrations of compounds such as 2-methyl-1-propanol, 3 methyl-1-butanol, isoamyl butyrate and acetoin.     

胎脂和羊毛脂中支链脂肪酸组成的研究

支链脂肪酸(BCFA)是胎脂的重要成分,胎儿吞食羊水可获取胎脂中的BCFA,从而参与发挥肠道的防御作用。早产儿吞食胎脂不足,肠道缺乏BCFA,需要外源补充,羊毛脂是潜在的BCFA的天然来源。对胎脂和羊毛脂的BCFA组成进行分析。结果表明:胎脂含有复杂的脂质种类,主要是非极性脂质;胎脂总脂质和胎脂甘油三酯中的BCFA含量都比较高,依次为17.16%、16.12%;胎脂中共检测到11种BCFA,其中异构C12∶0、异构C14∶0、异构C16∶0、反异构C15∶0的含量较高;羊毛脂的脂肪酸中含有约48.53%的BCFA,包括了胎脂中大部分可测得的BCFA,因此羊毛脂可以模拟胎脂中的BCFA,具有在早产儿配方食品中应用的价值。     

Age and nutrition influence the concentrations of three branched chain fatty acids in sheep fat from Australian abattoirs

The characteristic mutton odour, associated with the cooked meat of older sheep, can be problematic for some consumers who find the odour disagreeable. Branch chain fatty acids (BCFAs) are considered to be the main determinants of mutton odour. In this study, the aim was to identify the factors influencing the BCFA content of animals at abattoirs in Australia. Samples of subcutaneous fat from over the chump (gluteus medius) were collected from 533 sheep carcasses at abattoirs in New South Wales, Victoria and Western Australia. The carcasses were from sheep differing in age, gender, breed and nutrition. The concentrations of three branched chain fatty acids (BCFAs); namely, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic acids (MNA), were determined. Statistical modelling showed that, with pre-slaughter nutrition in the model as a random term, BCFA concentrations could be used for discriminating the age of sheep. Fat samples from lamb carcasses had lower MOA and EOA concentrations and a higher concentration of MNA in comparison to hogget and mutton (P < 0.05). When nutrition was excluded as a random effect from the statistical model, the MOA and MNA concentrations did not differentiate between lamb, hogget and mutton whereas, for EOA, lamb had a lower concentration than mutton (P < 0.05) with hogget intermediate. An interaction existed between age and gender (P < 0.05) where female lambs had lower EOA concentrations relative to the mutton but not for castrates.