Dietary manipulation of muscle long-chain omega-3 and omega-6 fatty acids and sensory properties of lamb meat

The effects of dietary manipulation of muscle long-chain omega-3 fatty acids (FA) on sensory properties of cooked meat in second cross ([Merino×Border Leicester]×Poll Dorset) wether lambs were evaluated. Lambs fed dietary supplements of fish meal (FM, Exp. 1) and fish oil (FO, Exp. 2) showed moderately (P<0.01) and markedly (P<0.001) increased muscle long-chain omega-3 FA content compared with those fed the basal diet of lucerne chaff and oat chaff. Protected canola seed (PCS, Exp. 1) significantly (P<0.001) increased omega-6 FA content of the longissimus muscle. In each of the 2 experiments (1 and 2), after being fed experimental diets for 6 weeks lambs were slaughtered at a commercial abattoir. At 24 h post-mortem (PM) the semitendinosus and biceps femoris muscles were removed from animals and stored at -20°C until evaluation of sensory properties using experienced panel members. The muscle samples were stored for 3 (Exp. 1) and 12 (Exp. 2) months then removed, thawed and cooked for sensory evaluation. The meat samples were cooked under standardized conditions in a convection microwave at 180°C (20-25 min) to an internal temperature of 75°C. Cooked samples were tested for flavour, aroma, juiciness and overall palatability. The significant increase in muscle long-chain omega-3 with FM (Exp. 1 and 2) and FO (Exp. 2) or omega-6 FA with PCS (Exp. 1) were not detrimental to sensory panel evaluations of flavour or aroma of cooked meat when compared with the basal diet. However, meat from FM (Exp. 1) had lower juiciness and FO (Exp. 2) had lower overall palatability. Protected sunflower meal protein with FO (Exp. 2) significantly lowered ratings for flavour, juiciness and overall palatability. Lamb meat with increased levels of long-chain omega-3 FA can be produced without altering the sensory quality (flavour or aroma) of the cooked meat.     

Distribution of volatile branched-chain fatty acids in various lamb tissues

Volatile fatty acids (C4–C11) including even-, odd-, and branched-chain members in lamb tissues were quantitatively analyzed. Volatile branched-chain fatty acids (BCFA) were more concentrated in subcutaneous adipose tissue samples (rump, shoulder, breast) than in perinepheric adipose or muscle tissues. Perinepheric adipose tissue contained relatively high quantities of n-chain, even-numbered fatty acids and very low levels of BCFA. Greater variation existed in fatty acid profiles among similar subcutaneous adipose tissues from different lambs than between samples of adipose tissue from different carcass sites from a given lamb sample. 4-Methyl- and 4-ethyloctanoic acids were present at concentrations greatly above threshold levels in all lamb fats tested, and thus upon hydrolysis would contribute species-related flavors to lamb. 4-Methylnonanoic concentrations in lamb fats ranged from nondetectable to greater than the threshold level, and therefore this compound would not always contribute to the species-related flavors of lamb. Lean meat samples contained very low concentrations of 4-methyl- and 4-ethyloctanoic acids.     

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.     

Nutritional and sensory aspects of light lamb meat enriched in n−3 fatty acids during refrigerated storage

Fatty acid content and sensory characteristics of meat from light lambs fed three diets supplemented with different sources of n−3 fatty acids (fish oil, extruded linseed and extruded linseed plus microalgae) and a control diet during refrigerated storage have been studied. The meat from lambs fed linseed diets had the highest levels of C18:3 n−3, while animals fed fish oil had the highest long-chain n−3 polyunsaturated fatty acids (PUFA). Thus, 100 g of meat from lamb fed the fish oil diet provided 183 mg of long-chain n−3 PUFA, representing 40% of the daily recommended intake. The levels of n−3, n−6 and long-chain n−3 PUFA decreased during a 7-day storage period. The meat from lambs fed the fish oil diet had high scores of fish odour and flavour and rancid odour and flavour and the lowest overall liking. Rancid odour and flavour increased after storage, mainly in supplemented groups.     

Effect of dietary soybean oil addition on the odd-numbered and branched-chain fatty acids in rabbit meat

The effect of dietary soybean oil (SO) inclusion (20 g/kg) on the odd-numbered (ONFA) and branched-chain (BCFA) fatty acids (FA) of two muscles, differing in fatness (Longissimus lumborum and Biceps femoris), was studied in 24 New Zealand × Californian rabbits. The increased muscle fatness in Biceps femoris (P < 0.001) was related to higher saturated (P < 0.01) and monounsaturated (P < 0.01) fatty acids. Intramuscular ONFA and BCFA contents were not affected, but their proportions were reduced (P < 0.01 and P < 0.001) by SO addition, suggesting a dilution effect of the dietary polyunsaturates accumulated in both muscles, except for 17:0i which decreased only in Longissimus lumborum due to significant (P < 0.05) soybean oil × muscle interaction. The higher (P < 0.05) BCFA contents and the FA profile in Biceps femoris were not affected by fatness, indicating an association with other muscle properties. The present study supplies new information on ONFA and BCFA in rabbit meat.     

Effect of sire breed on physico-chemical and sensory characteristics of lamb meat

Physico-chemical and sensory characteristics of lamb meat were evaluated in crossbred ram lambs from Merino ewes and Oxford Down, Texel, Charollais, Suffolk and Merinolandschaf sires. The lambs were slaughtered at average age 119.2 days, live weight 34.6 kg and carcass weight 16.3 kg. Samples of M. longissimus lumborum et thoracis were used for measurements of pH values, electrical conductivity (EC), drip loss, contents of dry matter (DM), protein, intramuscular fat (IMF), ash, and hydroxyproline and for sensory analysis. The breed of sire significantly affected pH 24 and 48 h postmortem, EC 24 h postmortem, protein content and juiciness (P < 0.05). Significant negative correlations between pH₄₈ and DM (− 0.255) and pH₄₈ and IMF (− 0.258) were found (P < 0.05). A significant positive correlation between EC₄₈ and drip loss (0.366) was observed (P < 0.05). Progeny of Charollais sires had meat of better quality than the others; the highest content of protein and IMF, the lowest drip loss and the best juiciness and texture.     

Effect of dietary replacement of sunflower oil with linseed oil on intramuscular fatty acids of lamb meat

The effect of stepwise replacement of dietary sunflower oil (SO) with linseed oil (LO) on carcass composition, meat colour and fatty acid (FA) composition of intramuscular lipids of lamb meat was investigated. Thirty-six lambs were fed one of four diets consisting of pellets of lucerne with oil (60 g/kg): the diet varied in the composition of oil added and were: 100% SO; 66.6% SO plus 33.3% LO; 33.3% SO plus 66.6% LO and 100% LO. The experimental period was 7 weeks. Live slaughter weight, hot carcass weight and intermuscular fat percentage of chump and shoulder increased linearly with replacement of SO by LO.     

Effect of chilling applied to suckling lamb carcasses on hygienic, physicochemical and sensory meat quality

The effect of post mortem temperature treatment on suckling lamb carcass and meat quality was study. Conventional (2°C for 24h), ultra-rapid (-20°C for 3.5h, 2°C until 24h) and slow chillings (12°C for 7h, 2°C until 24h) were compared. Total viable counts (TVC), weight losses, and pH and temperature falls were recorded on carcasses. Meat colour, water holding capacity (WHC), Warner-Bratzler shear force, sarcomere length and sensory analysis were evaluated in M. longissimus. Ultra-rapid treatment reduced TVC and weight losses. The pH decline was faster in slow chilled carcasses than in faster chilled carcasses. No significant differences were found for colour and WHC. Slow treatment carcasses showed significantly lower shear force and higher sarcomere length. In the sensory analysis, tasters also rated the early post mortem slow-treated meat as more tender, less fibrous and chewy. Therefore, delay chilling in suckling lamb carcasses made it possible to obtain meat with better organoleptic characteristics, without affecting weight loss or hygienic quality.     

Effect of chilling applied to suckling lamb carcasses on hygienic,physicochemical and sensory meat quality

The effect of post mortem temperature treatment on suckling lamb carcass and meat quality was study. Conventional (2 °C for 24 h), ultra-rapid (− 20 °C for 3.5 h, 2 °C until 24 h) and slow chillings (12 °C for 7 h, 2 °C until 24 h) were compared. Total viable counts (TVC), weight losses, and pH and temperature falls were recorded on carcasses. Meat colour, water holding capacity (WHC), Warner-Bratzler shear force, sarcomere length and sensory analysis were evaluated in M. longissimus. Ultra-rapid treatment reduced TVC and weight losses. The pH decline was faster in slow chilled carcasses than in faster chilled carcasses. No significant differences were found for colour and WHC. Slow treatment carcasses showed significantly lower shear force and higher sarcomere length. In the sensory analysis, tasters also rated the early post mortem slow-treated meat as more tender, less fibrous and chewy. Therefore, delay chilling in suckling lamb carcasses made it possible to obtain meat with better organoleptic characteristics, without affecting weight loss or hygienic quality.     

Associations of sire estimated breeding values and objective meat quality measurements with sensory scores in Australian lamb

The impact of selecting for lean meat yield using breeding values for increased eye muscle depth (PEMD) and decreased fat depth (PFAT) on the consumer acceptance of lamb meat was evaluated. Consumer sensory scores (tenderness, juiciness, flavour, odour, overall liking) were obtained for the longissimus lumborum (loin) and semimembranosus (topside) muscles of 1471 lambs. On average loin samples were more acceptable for consumers. Sensory scores increased with higher IMF levels, with lower shear force levels, and when animals were younger and less muscular. Increasing PEMD decreased tenderness, overall liking and flavour scores in both muscles, and decreasing PFAT reduced tenderness within the loin samples only. This negative impact of PEMD and PFAT is not solely driven through the phenotypic impact of IMF and shear force on sensory scores. Our results confirm the growing concerns that selecting for lean meat yield would reduce consumer eating quality, and highlight that careful monitoring of selection programmes is needed to maintain lamb eating quality.     

Effect of cooking methods and freezing storage on amino acids constituents of lamb meat

The flavour of cooked meat and the acceptability of frozen meat, especially those of lamb meat, are affected to a great extent by methods of cooking such as boiling or roasting. These methods of cooking degrade meat protein as an activity of proteolytic enzymes during storage. Amino acids contents, especially essential ones, decreased during freezing and storage in both selected muscles (Longissimus dorsi muscle and Biceps femoris muscle) under investigation. Roasting was favoured as a cooking method compared with boiling methods, as the latter proved lower amounts of essential amino acids [1–3].     

Effect of antioxidants on stabilization of meat products fortified with n-3 fatty acids

The effects of an n-3 oil emulsion, with and without added antioxidants, on lipid oxidation in n-3 polyunsaturated fatty acid (PUFA)-fortified meat products were studied. An emulsion of n-3 PUFAs was prepared (25% algal oil, 2.5% whey protein isolates, 10mM sodium citrate, 0.2% potassium sorbate, 500ppm of 70% mixed tocopherols, 100μM EDTA, pH 3, pasteurized at 75°C for 30min) and incorporated into fresh ground turkey, and fresh pork sausage (20% fat) to achieve a concentration of 500mg n-3 PUFA/110g meat. An antioxidant combination containing rosemary (0.2% w/w; radical quencher), citrate (0.5% w/w; sequestrant) and erythorbate (1g/kg product; reductant) was prepared and incorporated into ground turkey patties (5cm dia, 1.5cm thick) or fresh pork sausages (5cm dia, 1.5cm thick). Meat products were stored at 4°C or -18°C and analyzed for color (L*, a*, b* values), lipid oxidation (TBARS and lipid hydroperoxides) and n-3 PUFA profile. a* Values of refrigerated ground turkey patties decreased with storage, and an antioxidant combination effect was observed after 4 days (P<0.05). For fresh pork sausages at 4°C, control+antioxidant (CON+ANTI), and n-3+antioxidant (n-3+ANTI) groups showed greater a* values than controls (CON) indicating that the antioxidant combination stabilized meat color. TBARS and lipid hydroperoxides of both n-3 PUFA-enhanced meat products increased with storage (P<0.05); there were no significant changes in TBARS or lipid hydroperoxides for treatments containing the antioxidant combination (P<0.05). The actual level of n-3 PUFA incorporation in both meat products was greater than 87%; n-3 PUFA concentrations did not change within any treatment during storage (P>0.05). These results provide support for including antioxidant protection in n-3 PUFA fortified meat products.     

Omega-3 fatty acids in pig nutrition: Implications for the intrinsic and sensory quality of the meat

Seventy-eight hybrid pigs (Piétrain × Seghers hybrid cross, 38 barrows and 40 gilts) were fed ad libitum diets, containing either 0.4%, 0.7% or 1.0% α-linolenic acid (C18:3n-3), originating from linseed. The variation in polyunsaturated fatty acid content in the feed (1.19%, 1.52% and 1.88%, respectively) was mainly attributed to variations in α-linolenic acid content. Meat quality evaluated by physical measurements (pH, light scattering, conductivity, colour, light reflection, tenderness, water holding capacity) was not influenced, to any significant extent, by the fatty acid composition of the feed. A subjective judgement of cohesiveness revealed no abnormalities. Dietary fat source, sex and intramuscular fat (IMF) level affected the fatty acid pattern of the IMF. The α-linolenic content in the IMF increased from 1.2% to 2.3% for the barrows and from 1.4% to 2.9% for the gilts with increasing αlinolenic acid content in the feed. A multiple paired comparison test for taste, tenderness and juiciness on 45 meat samples (M. longissimus thoracis) revealed no significant differences among the feed groups.     

支链脂肪酸的来源与功能研究进展

支链脂肪酸主要包括单支链脂肪酸和多支链脂肪酸,多存在于人体皮肤及其分泌物、微生物细胞膜、乳制品及肉制品中。近年来的研究表明,支链脂肪酸对乳腺癌细胞、前列腺癌细胞和膀胱癌细胞等具有潜在抑制作用,此外,支链脂肪酸还有抑制新生儿坏死性小肠结肠炎发病率等抗炎作用。进一步对各种食物以及人体各组织中的支链脂肪酸进行检测分析,并对支链脂肪酸结构功能与作用机理进行深入研究,是目前支链脂肪酸研究的重要方向。     

Dietary olive cake reduces the oxidation of lipids,including cholesterol,in lamb meat enriched in polyunsaturated fatty acids

Over 40 days, lambs were fed: concentrate (C), concentrate containing 20% linseed (L), concentrate containing 35% olive cake (OC), or concentrate containing 10% linseed and 17% olive cake (OCL). The polyunsaturated fatty acids (PUFA) and peroxidation index (PI) in phospholipids were increased by the L and OCL treatments (P = 0.007 and P = 0.003, respectively). The OC and OCL diets increased the concentration of tocopherol in muscle (P < 0.001). Compared to the OC and OCL diet, the L diet increased fatty acid oxidation, measured as conjugated dienes (CD; P = 0.003), peroxides (PV; P < 0.001) and TBARS (P = 0.002) in minced muscle over 11 days of storage in high-oxygen atmosphere. Also, the L diet increased (P < 0.001) the levels cholesterol oxidation products (COPs). In conclusion, feeding olive cake improved the oxidative stability of lamb meat and the combination of olive cake and linseed improved the fatty acid composition of meat without compromising its oxidative stability.     

Effect of heat on the fatty acids and aldehydes of veal meat phospholipids

Reactions involving phospholipids contribute considerably to the flavour and aroma of cooked meat. The effect of heat on the fatty acids and fatty aldehydes of phospholipids from veal was studied using aqueous model systems wherein extracted phospholipid fractions were heated in the presence or absence of ribose or glycine. After 1 h at 132°C, ethanolamine-containing phospholipids rapidly lost most of their component aldehydes but not their fatty acids, whereas choline-containing phospholipids lost their aldehydes much more slowly. In both cases, the presence of ribose or glycine had little effect on the loss of aldehydes. In the meat itself, after heating at 132°C, there was a 90% loss of aldehydes which was similar for both the ethanolamine- and choline-containing phospholipids, but the latter lost fatty acids more slowly than the former.     

Sources of variation of health claimable long chain omega-3 fatty acids in meat from Australian lamb slaughtered at similar weights

The sources of variation of health claimable omega-3 polyunsaturated fatty acids (eicosapentaenoic acid, EPA + docosahexaenoic acid, DHA) in 2000 Australian lambs were investigated using 98 sires (Merino, maternal or terminal breeds) that were mated to about 5000 Merino or crossbred (Border Leicester × Merino) ewes. Pasture was supplemented with feedlot pellets, grains or hay as necessary, when the availability of quality green pasture was limited. Lambs were grown at 8 sites across Australia and when slaughtered the longissimus lumborum muscle was collected. Site and kills within sites were the major sources of variation for health claimable fatty acids. These environmental effects are likely to be driven by dietary background. The sire variance differed from about one twentieth to a half of the residual lamb within dam variation, depending on site and kill. This is the first comprehensive study to investigate on-farm sources of variation of long chain omega-3 polyunsaturated fatty acid content of lamb meat.     

Effect of electrical stunning on meat quality of lamb

The effects of stunning on both initial and up to 2 weeks post mortem storage meat quality of Spanish Manchega breed lamb were studied. Twenty-four lambs were distributed into two groups. The first group (US; n =12) were slaughtered without previous stunning. In the second group (ES; n =12) animals were electrically stunned. Meat quality was assessed by examining pH, colour as L*, a*, b* values, water holding capacity (WHC) and shear force (SF). Stunning did not affect any parameter studied in the first 24 h post mortem. There were increasing differences between groups in pH (P<0.001) from 5 days onwards. In general stunning did not have an effect on WHC, SF and colour parameters. Ageing of meat affected SF in the ES group but not in the US one; however, there were no significant differences between treatments at any of the ageing times.