Prediction of sensory characteristics of lamb meat samples by near infrared reflectance spectroscopy

This study was implemented to evaluate the potential of visible and near infrared reflectance (NIR) spectroscopy to predict sensory characteristics related to the eating quality of lamb meat samples. A total of 232 muscle samples from Texel and Scottish Blackface lambs was analyzed by chemical procedures and scored by assessors in a taste panel (TP). Then, these parameters were predicted from Vis/NIR spectra. The prediction equations showed that the absorbance data could explain a significant but relatively low proportion of the variability (R(2)<0.40) in the taste panel traits (texture, juiciness, flavour, abnormal flavour and overall liking) of the lamb meat samples. However, a top-tail approach, looking at the spectra of the 25 best and worst samples as judged by TP assessors, provided more meaningful results. This approach suggests that the assessors and the spectrophotometer were able to discriminate between the most extreme samples. This may have practical implications for sorting meat into a high quality class, which could be branded, into a low quality class sold for a lower price for less demanding food use. Regarding the chemical parameters, both intramuscular fat and water could be more accurately predicted by Vis/NIR spectra (R(2)=0.841 and 0.674, respectively) than sensory characteristics. In addition, the results obtained in the present study suggest that the more important regions of the spectra to estimate the sensory characteristics are related to the absorbance of these two chemical components in meat samples.     

Lipid composition of Australian retail lamb cuts with differing carcass classification characteristics

The gross, proximate, fatty acids and cholesterol composition of three raw retail cuts from 28 lambs classified by weight, sex and fatness score were investigated. For gross composition, cut weight increased significantly with fat score and carcass weight. Percentage fat increased significantly from fat score 1–2 but not beyond (P<0.05). For nutrient composition the fat contents of the total cut and lean only portion of the three cuts increased directly with fat score by 10 g/100 g and 1.7 g/100 g, respectively. Fat content increased mainly at the expense of moisture. Cholesterol content of total cut and lean only portions decreased with increased fat score, by 16 and 18 mg/100 g, respectively. For lean only levels of myristic and palmitic acids increased significantly (P<0.05) while stearic acid decreased significantly, while levels of linoleic and linolenic acids decreased significantly with increased fat score.     

Eating quality of lamb meat: effects of breed, sex, degree of maturity and nutritional management

The eating quality of lamb meat of three indigenous Greek dairy breeds of sheep, reared under different nutritional management conditions, was assessed by Taste Panel Tests (TPT). Lean samples from the leg joints of 69 lamb carcasses of the Boutsko (B), Serres (S) and Karagouniko (K) breed were used. For the first TPT, 24 lambs (four males and four females of each breed) were reared in individual pens on a concentrate ration fed ad libitum. For the second TPT, 27 individual penned male lambs were fed on Lucerne hay ad libitum and on three different levels of concentrate: High (H), Medium, (M) and Low (L). For the third TPT, 18 male lambs were used; initially the groups were fed indoors for 63 days on three different levels of concentrate (H, M and L) together with ad libitum Lucerne hay, and subsequently finished on irrigated, sown pasture. For TPT 1, leg joints were obtained from lambs that had been slaughtered at 30, 45, 60 or 90% of mature weight (PMW) for each breed. For TPT 2, lambs were slaughtered at 23, 28 or 33 kg target slaughter live weights (TSLW), common for all breeds. For TPT 3, lambs were slaughtered at 48 or 55% of PMW for each breed. Panellists assessed warm, roasted lean samples of leg joints and rated Flavour, Juiciness, Tenderness and Overall Acceptability. In TPT 1, degree of maturity significantly affected Flavour, Tenderness and Overall Acceptability whereas sex affected only Flavour. In TPT 2, breed and concentrate level significantly affected the quality characteristics, but concentrate level had no significant effect in TPT 3. Effects associated with slaughter weight were significant for most characteristics in all TPT, with decreasing acceptability for older/heavier lambs. Significant interactions were found between breed and the other factors in TPT 2 and TPT 3 for most quality characteristics. Results from these studies suggest changing traditional production systems may enhance the eating quality of lamb meat.     

Predicting the composition of lamb carcases using alternative fat and muscle depth measures

Hot carcase weight (HCW) and the GR tissue depth (total tissue depth over the 12th rib, 110 mm from the midline) were measured on 312 crossbred (Poll Dorset × Merino) lambs with a mean live weight of 47 kg. At a position 30 mm distal to the lumbar-sacral junction, the depth (RMD) of the rump muscles was measured along with subcutaneous fat depth overlaying the m. gluteus medius (RFD). The subcutaneous fat depth over the m. longissimus (loin) at the 12th rib was measured (Fat C), as was the depth and width of the loin cross section (EMD and EMW, respectively). The right side of each carcase was scanned by a dual energy X-ray bone densitometer and fat and lean weight determined and the percentage of lean and fat content in the carcases calculated. HCW alone accounted for 26% of the variation in percentage lean content (LC), with GR measurement being the single best predictor of LC (R² = 48.1; r.s.d. = 1.89). RFD provided a less accurate and precise estimate of LC (R² = 37.3; r.s.d. = 2.07) than either GR or Fat C (R² = 46.5; r.s.d. = 1.92). Inclusion of HCW with either GR or Fat C provided a small improvement in the amount of variation in LC which could be explained. The measurement of breeding animals by ultrasound includes the terms weight, Fat C and EMD. These predictors when combined explained 49% of the variation in LC whereas by comparison measures of weight, RFD and RMD only explained 42% of the variation in LC. The current method of measuring fat depth over the 12th/13th rib is practical and measurement over the rump does not present an advantage based on the results of this study.     

Effect of morning vs. afternoon grazing on intramuscular fatty acid composition in lamb

The aim of this study was to assess whether different grazing management affect animal performance and meat fatty acid composition. Thirty-five lambs were divided into three groups: 12 lambs grazed from 9 am to 5 pm (8h group); 11 lambs grazed from 9 am to 1 pm (4hAM group) and 12 lambs grazed from 1 pm to 5 pm (4hPM group). The trial was conducted over 72 days. The 8h lambs had greater DMI (P < 0.0005) and final body weight (P < 0.05) than the 4hPM and 4hAM lambs while carcass weight was not different between the three groups. The meat of the 4hPM lambs contained greater (P < 0.05) percentages of polyunsaturated fatty acids, C18:2 cis-9 trans-11 and lower saturated fatty acids and C18:0 than the meat of the 8h and 4hAM lambs. It is concluded that allowing lambs to graze during the afternoon rather than during 8 h does not compromise the carcass yield and results in a healthier meat fatty acid profile.     

Utilization of extruded linseed to modify fatty composition of intensively-reared lamb meat: Effect of associated cereals (wheat vs. corn) and linoleic acid content of the diet

Sixty male lambs were used in two trials to study the efficiency of transfer and elongation of linolenic acid (ALA) in muscle and caudal adipose tissue and to assess factors affecting this process and related changes in fatty acid (FA) profile. In experiment 1, lambs were fed a control diet or extruded linseed (L) diet either with wheat (W, rapid starch) or corn (C, slow starch). In experiment 2, lambs were fed L with “normal” rapeseed, or high-oleic rapeseed, or soybean. In experiment 1, L increased ALA proportion and total n-3 PUFA in muscle and adipose tissue. In adipose tissue but not in muscle, LC lambs had higher proportion of ALA than LW lambs. In experiment 2, increasing linoleic acid (LA) intake increased LA proportion in muscle and adipose tissue but did not modify ALA proportion. Moreover, in muscle, it did not change the desaturation and elongation processes of ALA to long-chain n-3 PUFA.     

Fatty acid composition and carcass characteristics of growing lambs fed diets containing palm oil supplements

Thirty 45-day-old male Ojalada lambs were used to investigate the effect of palm oil (as such or in the form of calcium soap) on carcass characteristics and fat composition. Dietary palm oil did not significantly affect dorsal fat thickness, carcass fatness or carcass conformation. The palm oil supplement did not affect C16:0 levels in intramuscular and subcutaneous fat, but did increase the percentage of C16:0 and reduce PUFA and MUFA content in internal fat depots. Supplementation with palm oil in the form of calcium soap did not cause significant differences in the composition of intramuscular fat. Subcutaneous and perirenal fat of lambs fed treatments including palm oil as such contained higher levels of some saturated fatty acids than that of those fed fat in the form of calcium soap. Mesenteric fat of lambs that received calcium soap had less % C18:1 and more % C18:3 than that of those given palm oil.     

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.     

Prediction of lamb carcass composition and meat quality using combinations of post-mortem measurements

Various post-mortem measurements (carcass weights, conformation and fatness classes, external carcass dimensions, eye muscle dimensions, subcutaneous fat depth, pH and temperature) were recorded on 197 Texel (TEX) and 200 Scottish Blackface (SBF) lamb carcasses. The potential use of these measurements to predict carcass composition and key meat quality traits was investigated, to enable categorisation of carcasses in the abattoir and/or for use in genetic improvement programmes. By combining different measurements, accurate predictions of dissected carcass muscle weight (adjusted R² 0.93 in TEX, 0.88 in SBF) and fat weight (adjusted R² 0.84 in TEX, 0.87 in SBF) were achieved, and moderate predictions of intra-muscular fat (adjusted R² 0.56 in TEX, 0.48 in SBF), whilst shear force was predicted with low to moderate accuracy (adjusted R² < 0.33 across breeds and cuts). Sex, eye muscle dimensions and subcutaneous fat depth improved predictions of carcass composition and intra-muscular fat, whilst pH or temperature provided little additional benefit for these traits, but increased prediction accuracies for shear force. These results could contribute to the development of automated carcass grading systems or help inform breeding decisions.     

Effect of dietary oregano oil supplementation on lamb meat characteristics

The effect of dietary oregano essential oil supplementation on lamb meat characteristics was investigated. Eight male and eight female Chios lambs were divided into two equal groups. The first group was fed with the control diet consisting of concentrated feed and alfalfa hay, whereas the second group consumed the same diet, the only difference being that the concentrated feed was uniformly sprayed with oregano essential oil (1 ml/kg). Duration of the experimental period was two months.

No differences were observed after oregano essential oil supplementation in final body weight (kg), body weight gain (g) and carcass yield (%). Tenderness of longissimus thoracis muscle, expressed as sarcomere length and shear force value, was not influenced by the treatment, whereas pH and colour parameters (yellowness–redness) appeared to increase (P < 0.05). Moreover, results showed that dietary incorporation of oregano essential oil exerted strong antioxidant effects retarding lipid oxidation (MDA formation) in meat during refrigerated and long-term frozen storage (P < 0.001).     

True retention of nutrients on cooking of Australian retail lamb cuts of differing carcass classification characteristics

The true retention of nutrients (proximate principles and cholesterol) on cooking of three retail cuts from lambs classified by weight, sex and fatness score was investigated. Fat retentions of the total cut and of the lean portion of lamb legs and mid-loin chops were not affected by carcass fatness, weight and sex or their interactions, however, the fat retention of the total cut and of the lean portion of forequarter chops was affected by fat score, with forequarter chops from fat score 1 retaining more fat than did chops of carcasses of higher fat score. Overall, fat was lost by all cuts (total cut) on cooking, with only 70–80% of fat being retained, but fat content of lean only increased on cooking (retention >100%), indicating the passage of fat into the lean portion from the external fat cover during the cooking process. Carcass factors and their interactions had little or no effect on the protein, water and ash retentions of the total cut or the lean portions of the three cuts. Cholesterol retention by the lean portion of three cooked lamb cuts was not affected by any carcass factors or their interactions. Cholesterol retentions were 99% for total cuts and tended to be 102% for the lean portions.     

Fatty acid composition and sensory traits of beef fed palm oil supplements

This study measured the effect of replacing dietary fat from an animal source with palm oil supplements on the intramuscular fatty acid profile and sensory quality traits of the meat from young bulls. Thirty-six entire male Friesian calves (mean age=6.8±1.1 months, mean live weight=162.5±28.6kg) were assigned to one of four isoenergetic (1.03 MFU/kg DM) and isoproteinic (15.5% CP) diets, that differed in their fat additives: (D1) lard-tallow mix (control); (D2) hydrogenated palm oil fatty acids (PFA); (D3) calcium salt of partially hydrogenated PFA, and (D4) calcium salt of the fatty acid distillate from palm oil. Bulls (mean live weight=391.3±30.3kg) were slaughtered under commercial conditions and sensory tests were performed to evaluate the effects of the four diets and ageing time (1, 10, and 21d). Only the proportions of C16:0 and C18:0 were significantly affected by the palm oil dietary supplement. Ageing time affected grass odour, tenderness, juiciness, fibrosity, liver flavour, and acid flavour. Nevertheless, palm oil supplements did not negatively alter the organoleptic characteristics of the meat.     

Irradiation effect on fatty acid composition and conjugated linoleic acid isomers in frozen lamb meat

The effect of gamma radiation processing on the lipid content, fatty acid composition and conjugated linoleic acid (CLA) profile in frozen lamb meat was investigated. Samples of longissimus thoracis muscle from lambs fed lucerne basal diets either unsupplemented or supplemented with polyunsaturated vegetable oils were irradiated (7 kGy) and analysed. CLA contents in lamb meat did not affect (P > 0.05) the levels of lipid oxidation induced by the irradiation. No significant differences (P > 0.05) were observed for fatty acid composition, related nutritional indexes (n − 6/n − 3 and PUFA/SFA), as well as for total lipid and CLA contents, between non-irradiated (control) and irradiated meat samples. In contrast, meat irradiation affected the relative proportions of total trans, trans and cis/trans CLA isomers (P < 0.001), in addition to the percentage of some minor individual CLA isomers (t11, t13 and t9, t11, with P < 0.05 and P < 0.001, respectively). The percentage of total cis/trans CLA isomers slightly decreased in irradiated samples, while the relative proportion of total trans, trans isomers slightly increased. This observation may be explained by the higher susceptibility to autoxidation of the cis double bond relative to the trans configuration.     

Mineral composition of lamb carcasses from the United States and New Zealand

The mineral composition-iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), fluoride (F), and phosphorus (P) (New Zealand lamb only)-of lean tissue from lamb retail cuts was studied. Twenty-four US lamb carcasses of different ages (5 to 11 months), geographical regions (Texas, Colorado and Montana) and USDA quality grades (Prime and Choice) and 27 New Zealand lamb carcasses from three weight groups (11 to 12·5 kg, 13 to 14·5 kg, and 16·5 to 18 kg), age rangining from 7 to 8 months, were selected for use in this study. Mineral concentrations were influenced more by retail cut and age than by quality grade or weigth group. Foreshank and shoulder cuts from both the US and New Zealand group consistently had the highest (P < 0·05) Zn content among the cuts. The K content of the muscle in US lambs increased as age increased, while the level of Ca and Zn in New Zealand lambs decreased as carcass weight increased. Except for Ca, the mineral concentrations of the lean tissue from US lambs were higher than the New Zealand lambs, although the differences were not always significant. US lambs had approximately 20%, 30% and 37% more Fe, Zn and Mg, respectively, but 27% less Ca than lean tissue from the New Zealand lambs.     

Effect of live weight and sex on physico-chemical and sensorial characteristics of Merino lamb meat

Forty-eight lamb carcasses were divided into four groups (n = 12) according to slaughter weight (24 and 29 kg) and sex (male and female). Colour, pH, moisture, and intramuscular fat were not affected (p > 0.05) by slaughter weight or sex. With respect to fatty acid composition, slaughter weight had significant effects on C12:0 (p < 0.01), C14:0, C16:0, and C18:1 n-9 (p < 0.05) in Longissimus lumborum (LL) muscle. The percentage of C12:0 and C14:0 decreased as slaughter weight increased, while C16:0 increased. In Semimembranosus (SM) m., only C18:3 n-3 and C20:2 n-6 were affected (p < 0.001) by slaughter weight. Total PUFA in LL m. was greater (p < 0.01) in females than in males. Although in general, sensorial quality was not significantly affected by slaughter weight or sex, meat from lighter lambs (24 kg) had greater general acceptability than meat from heavier lambs (29 kg).     

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.     

Prediction of lamb meat fatty acid composition using near-infrared reflectance spectroscopy (NIRS)

The aim of this study was to assess the feasibility of near-infrared reflectance spectroscopy (NIRS) for predicting lamb meat fatty acid composition. We compared ground vs. intact non-ground meat samples to determine whether grinding and homogenisation of meat samples improved the performance of the predictions. We used 76 male lambs, of which 32 were pasture-fed and 44 stall-fed with concentrate and hay. The reflectance spectrum of Longissimus lumborum muscle was measured at wavelengths between 400 and 2500 nm. Predictions were better with ground than with intact muscle samples. NIRS accurately predicts several individual fatty acids (FA) (16:0, 18:0, 16:1 Δ9 cis, 17:1 Δ9 cis, 18:1 Δ9 cis, 18:1 Δ11 cis and 16:1 Δ9 trans) and several FA groups (total linear saturated FA, total branched saturated FA, total saturated FA, total cis monounsaturated FA (MUFA), total trans MUFA, total MUFA and total polyunsaturated PUFA). These results show the potential of NIRS as a rapid, and convenient tool to predict the major FA in lamb meat.     

Redberry juniper as a roughage source in lamb feedlot rations: wool and carcass characteristics, meat fatty acid profiles, and sensory panel traits

Effects of replacing cottonseed hulls with juniper leaves on end products were investigated in lambs. Lambs were individually fed diets containing cottonseed hulls (CSH), half of the CSH replaced by juniper (CSHJ), or all the CSH replaced by juniper (JUN). Lambs grew the same amount of wool when measured as greasy fleece (P > 0.19), clean fleece (P > 0.46), and clean wool production per unit of BW (P > 0.54). Average fiber diameter quadratically decreased (P = 0.04) and became more uniform (P < 0.04) as percentage of juniper increased in the diet. Carcass characteristics were not affected (P > 0.16) by diet. Myristic, palmitoleic, and arachidic acids, cis-9, trans-11 CLA, and the ?9 desaturase index linearly increased (P < 0.09) and stearic acid linearly decreased (P = 0.05) as percentage of juniper increased in the diet. Off-flavor linearly increased (P = 0.02) as juniper increased in the diet.     

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.