National beef tenderness survey - 2006: Assessment of Warner-Bratzler shear and sensory panel ratings for beef from US retail and foodservice establishments

Beef from retail and foodservice establishments in 11 US cities was evaluated using Warner-Bratzler shear (WBS) and consumer evaluation panels. Postmortem aging times ranged from 3 to 83d for retail and 7 to 136d for foodservice with mean aging times of 22.6d and 30.1d, respectively. For retail, the three cuts from the round - top round, bottom round, and eye of round - had the highest (P<0.05) WBS values compared to cuts from the chuck, rib, and loin. Top loin steaks had the lowest (P<0.05) WBS value compared to ribeye and top sirloin foodservice steaks. Retail bone-in top loin, top loin, ribeye, T-bone, and porterhouse received the highest (P<0.05) ratings by consumers for overall like and like tenderness. Quality grade had little or no effect on foodservice sensory evaluations. Improvements in round tenderness are needed to increase consumer acceptability.     

Physical, chemical, histological and palatability characteristics of muscles from three breed-types of cattle at different times-on-feed

Forty-five steers (9-12 months of age) of Angus (n =15), Brahman (n = 15) and Brahman × Angus (n = 15) breed-types were fed a high-energy diet and then slaughtered after 0, 112 or 224 days of feeding. At 7 days post mortem, the M. longissimus and M. biceps femoris were removed from the left side of each carcass and steaks were obtained for determination of sensory panel ratings, Warner-Bratzler shear force, sarcomere length, collagen content and collagen solubility. Tenderness ratings of steaks from the M. longissimus and M. biceps femoris from Angus were generally higher than ratings for steaks from Brahman or Brahman × Angus steers. Steaks from Brahman × Angus received higher tenderness ratings than steaks from Brahman steers in only a few comparisons. The three breed-types of cattle responded to time-on-feed differently; Brahman cattle needed to have been fed longer than Angus cattle to produce equally tender beef. With increased time-on-feed, M. longissimus tenderness increased for all breed-types, but M. biceps femoris tenderness was not related to time-on-feed. Few significant differences were observed among breed-types and among time-on-feed periods for collagen content or collagen solubility. Tenderness differences were closely correlated with the contractile state of the muscle which, in turn, was associated with weight, subcutaneous fat thickness and temperature decline of the carcass.     

Effect of lamb age and retail packaging types on the quality of long-term chilled lamb loins

The objective of this study was to determine the impact of lamb age and packaging types on meat quality. Paired loins (M. longissimus dorsi) were obtained from 36 carcasses that included 4-month-old (New season; NS) and 11-month-old lambs (Old season; OS). The loins were vacuum-stored for eight weeks at − 1.5 °C. After storage, the loins were cut into subsamples and were randomly assigned to either high-oxygen modified atmosphere packaging (HiOx-MAP) or PVC-overwrapping for further display for 8 days. No differences between the age classes in shear force and drip loss were found (P > 0.05). OS loins had significantly higher myoglobin and redness compared with NS loins. HiOx-MAP initially induced a more intense red colour compared with PVC (P < 0.05), but resulted in severe discolouration at the end of display regardless of the age class. This observation suggests that the retail packaging type is the dominant factor over the age on lamb colour stability.     

Selection of muscles as indicators of tenderness after seven days of ageing

The selection of a muscle that could be used as an index muscle for beef tenderness was performed using nine commercially important muscles. A total of 50 bulls, Charolais × Alentejano (n = 9), Simmental × Alentejano (n = 9) and Alentejano (n = 32), were slaughtered at two different commercial live weights: crossbred animals (sample A) between 500 and 600 kg (carcass weight between 310 and 370 kg) and purebred Alentejano (sample B) between 350 and 450 kg (carcass weight between 185 and 295 kg). Slaughter ages varied between 16 and 24 months in both groups. The shear force of nine muscles (Mm. biceps femoris, gastrocnemius, longissimus thoracis, longissimus lumborum, quadriceps femoris, semimembranosus, semitendinosus, supraspinatus and triceps brachii caput longum) was assessed seven days post-mortem. In both samples, the comparison between different muscle means and the combined mean of all muscles and the respective correlations showed that the Mm. biceps femoris and semimembranosus could be used as index muscles. However, the biceps femoris is preferred, because it showed greater stability in terms of the coefficient of variation.     

Lateral and longitudinal characterization of color stability, instrumental tenderness, and sensory characteristics in the beef semimembranosus

The objectives of this study were to evaluate longitudinal and lateral variations in color stability and sensory characteristics of the semimembranosus from each muscle location (dorsal = D, medial = M, ventral = V), and within each steak subsequently divided into four regions (caudal-distal = CaD, cranial-distal = CrD, caudal-proximal = CaP, cranial-proximal = CrP). Instrumental color assessment indicated that L^* (lightness) values tended to be lower for the CaD and CrD regions of all muscle locations, with higher L^* values recorded for the CrP regions of muscle sections. Instrumental tenderness measurements for Meullenet–Owens razor and Warner–Bratzler shear force values were generally lower for the CaD region of the D section, whereas regions within the V section were tougher and required greater shear force. Sensory panelists perceived lower amounts of connective tissue in the CaD of the D section, which tended to be more tender, whereas higher levels of connective tissue and greater toughness occurred in the CaP and CrP regions of the M and V sections. These results provide a detailed muscle profile of the quality variation within the semimembranosus, and may be used to further enhance the fabrication and marketability of this beef subprimal cut.     

Non-destructive assessment of instrumental and sensory tenderness of lamb meat using NIR hyperspectral imaging

The purpose of this study was to develop and test a hyperspectral imaging system (900–1700 nm) to predict instrumental and sensory tenderness of lamb meat. Warner–Bratzler shear force (WBSF) values and sensory scores by trained panellists were collected as the indicator of instrumental and sensory tenderness, respectively. Partial least squares regression models were developed for predicting instrumental and sensory tenderness with reasonable accuracy (R_cv = 0.84 for WBSF and 0.69 for sensory tenderness). Overall, the results confirmed that the spectral data could become an interesting screening tool to quickly categorise lamb steaks in good (i.e. tender) and bad (i.e. tough) based on WBSF values and sensory scores with overall accuracy of about 94.51% and 91%, respectively. Successive projections algorithm (SPA) was used to select the most important wavelengths for WBSF prediction. Additionally, textural features from Gray Level Co-occurrence Matrix (GLCM) were extracted to determine the correlation between textural features and WBSF values.     

Tenderness of pre- and post rigor lamb longissimus muscle

Lamb longissimus muscle (n=6) sections were cooked at different times post mortem (prerigor, at rigor, 1dayp.m., and 7 days p.m.) using two cooking methods. Using a boiling waterbath, samples were either cooked to a core temperature of 70 °C or boiled for 3h. The latter method was meant to reflect the traditional cooking method employed in countries where preparation of prerigor meat is practiced. The time postmortem at which the meat was prepared had a large effect on the tenderness (shear force) of the meat (P<0.01). Cooking prerigor and at rigor meat to 70 °C resulted in higher shear force values than their post rigor counterparts at 1 and 7 days p.m. (9.4 and 9.6 vs. 7.2 and 3.7 kg, respectively). The differences in tenderness between the treatment groups could be largely explained by a difference in contraction status of the meat after cooking and the effect of ageing on tenderness. Cooking pre and at rigor meat resulted in severe muscle contraction as evidenced by the differences in sarcomere length of the cooked samples. Mean sarcomere lengths in the pre and at rigor samples ranged from 1.05 to 1.20 μm. The mean sarcomere length in the post rigor samples was 1.44 μm. Cooking for 3 h at 100 °C did improve the tenderness of pre and at rigor prepared meat as compared to cooking to 70 °C, but not to the extent that ageing did. It is concluded that additional intervention methods are needed to improve the tenderness of prerigor cooked meat.     

Fatty acid composition and sensory characteristics of lamb carcasses from Britain and Spain

Fatty acid composition of intramuscular fat in M. Longissimus was measured in four groups of lambs representing two Spanish breeds: Rasa Aragonesa (RA) and Merino (ME) and two British lamb types: the Welsh Mountain breed (WM), whose carcasses were purchased in Spain and typical early lambs (EL) purchased in Britain. The lambs grown in Spain were concentrate fed and slaughtered at a lighter weight and lower age than those grown in Britain. The British lamb carcasses purchased in Spain were of a similar weight to the Spanish lambs but were lighter than the lamb carcasses purchased in Britain. The British lambs were grass fed. Relationships between fatty acid (FA) composition and sensory attributes were examined following sensory testing of all lambs by both British and Spanish taste panels. The production system was shown to be more important than breed in determining FA composition. British lambs had higher percentages, within total fatty acids, of 18:0, 18:3 (n-3) and long chain polyunsaturated n-3 FA and lower percentages of 18:2 (n-6) and long chain polyunsaturated n-6 FA than Spanish lambs. These differences were due to the different feeding systems used. The amounts of these FA in muscle (mg/100 g) were also different between the British and Spanish groups, not only because the British lambs had more total fat. For both taste panels, odour and flavour intensity were positively correlated with the amounts and percentages of 18:0 and 18:3 and negatively correlated with those of 18:2. This was explained by the fact that both panels gave higher odour and flavour intensity scores to the grass-fed British lamb with high 18:3 levels and lower scores to the concentrate-fed Spanish lamb with high 18:2 levels. However, 18:0 and 18:3 were positively correlated with flavour quality and overall appraisal for the British panel and negatively for the Spanish panel. Conversely, 18:2 was a positive contributor to flavour and overall preference for the Spanish panel and was negative for the British panel. The results show that the production system affects muscle fatty acid composition and the flavour of lamb. However, people's preference is determined to a large extent by their past experience.     

Contribution of myofibrillar and connective tissue components to the Warner-Bratzler shear force of cooked beef

Myofibrillar (MF-SF) and connective tissue (CT-SF) peak shear forces were interpolated from Warner-Bratzler shear force (SF) deformation curves of cooked bovine M. gluteus medius (GM) and M. semitendinosus (ST) from 112 crossbred steers in a 2×2×2 factorial experiment examining the interactions between slaughter age, growth promotants and breed cross (British versus Continental). Mixed model analyses, Pearson correlations and stepwise multiple regression identified relationships between shear forces, meat quality measurements and production treatments. Connective tissue contribution to SF increased with slaughter age and implantation in the ST and with slaughter age only in the GM. Myofibrillar contribution to SF increased with slaughter age for the ST and with Continental genetics for the GM. Variation in ST SF and MF-SF was best described by muscle weight, which increased with animal age, while GM SF and MF-SF variation was best described by cooking loss, indicating that ST and GM SF were most affected by connective and myofibrillar proteins, respectively.     

Evaluation of the Hennessy Grading Probe for use in lamb carcases

An evaluation of the Hennessy Grading Probe (HGP) was undertaken using 557 lamb carcases for the measurement of subcutaneous fat depth (Fat C) and muscle depth (EMD; m. longissimus thoracis et lumborum (LL)) between the 12th/13th ribs. All carcases were probed on the moving chain at up to 10 carcases per min and data analysis was constrained to 320 carcases which were probed at the target site (over the greatest depth of the LL at the midpoint between the 12th and 13th ribs). Analysis of the data revealed wide variability between HGP and equivalent carcase measures, but probe type (versions GP4 and GP7) had minimal impact on the usefulness of the HGP. The HGP as used in the study does not appear to be a viable option for the Australian sheep processing industry.     

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).     

Raman spectroscopy compared against traditional predictors of shear force in lamb m. longissimus lumborum

A Raman spectroscopic hand held device was used to predict shear force (SF) of 80 fresh lamb m. longissimus lumborum (LL) at 1 and 5 days post mortem (PM). Traditional predictors of SF including sarcomere length (SL), particle size (PS), cooking loss (CL), percentage myofibrillar breaks and pH were also measured. SF values were regressed against Raman spectra using partial least squares regression and against the traditional predictors using linear regression. The best prediction of shear force values used spectra at 1 day PM to predict shear force at 1 day which gave a root mean square error of prediction (RMSEP) of 13.6 (Null = 14.0) and the R² between observed and cross validated predicted values was 0.06 (R²_cv). Overall, for fresh LL, the predictability SF, by either the Raman hand held probe or traditional predictors was low.     

A model explaining and predicting lamb flavour from the aroma-active chemical compounds released upon grilling light lamb loins

The objective of the work is to understand the role of the different aroma compounds in the perception of the local “lamb flavour” concept. For this, a set of 70 loins (Longissimus dorsi) from approximately seventy day-old Rasa Aragonesa male lambs were grilled and the aroma-active chemicals released during the grilling process were trapped and analyzed. Carbonyl compounds were derivatizated and determined by GC-NCI-MS, whereas other aromatic compounds were directly analyzed by GC-GC-MS. Odour activity values (OAVs) were calculated using their odour threshold values in air. Lamb flavour could be satisfactory explained by a partial least-squares model (74% explained variance in cross-validation) built by the OAVs of 32 aroma-active chemical compounds. The model demonstrates that the lamb flavour concept is the result of a complex balance. Its intensity critically and positively depends to the levels of volatile fatty acids and several dimethylpyrazines while is negatively influenced by the different alkenals and alkadienals. (E,E)-2,4-decadienal and (E)-2-nonenal showed top OAVs.     

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.     

Carcass traits, muscle characteristics, and palatability attributes of lambs expressing the callipyge phenotype

Dorset×Suffolk crossbred wethers expressing a normal phenotype (normal, n=10) and callipyge phenotype (CLPG, n=9) were fed individually and slaughtered upon reaching maximum growth potential. Carcass weight did not differ (P>0.05), but fat thickness was lower (0.30 vs. 0.56 cm), ribeye area was greater (24.4 vs. 16.6 cm²), and USDA yield grade was improved (1.6 vs. 2.6) for CLPG carcasses (P < 0.05). Carcasses from CLPG demonstrated higher cutability and a more desirable muscle to bone ratio, with less fat and more lean as a percentage of total side weight (P<0.05). Biceps femoris (BF), semitendinosus (ST), semimembranosus (SM), longissimus thoracis et lumborum (LTL), and triceps brachii (TB) were used to compare muscle characteristics of both phenotypes. Muscle from normal lambs had lower calpastatin activity, higher fat percentages and lower moisture percentages (P<0.05). Total amount and solubility of collagen were not affected by phenotype nor was sarcomere length. Shear force and trained sensory attributes were evaluated for BF and LTL only. Shear force values did not differ between normal and CLPG BF while CLPG LTL had higher (P< 0.05) shear force values than normal LTL. Biceps femoris did not differ between phenotypes in trained sensory panel ratings. However, CLPG LTL received the lowest sensory ratings for connective tissue amount and myofibrillar and overall tenderness (6.11, 4.97, and 4.95, respectively) and the normal LTL received the highest ratings (P < 0.05; 7.10, 7.00, and 6.90, respectively). The CLPG phenotype had a positive influence on carcass characteristics but had a negative influence on tenderness of some muscles, possibly through the myofibrillar component of the muscle.     

Effect of vitamin E supplementation and diet on fatty acid composition and on meat colour and lipid oxidation of lamb leg steaks displayed in modified atmosphere packs

Groups of 8 lambs were allocated to one of five concentrate diets supplemented with all-rac-α-tocopheryl acetate containing 30 (C30), 60 (C60), 120 (C120), 250 (C250) and 500 (C500) mg/kg dry matter. Two other groups were fed grass silage and 400 g/day concentrate with 60 (S60) or 500 (S500) mg α-tocopheryl acetate/kg dry matter. Within diet, vitamin E level did not affect growth performance or carcass characteristics. Basal diet did not affect final live weight, conformation and fatness scores. M. semimembranosus from S lambs contained more α-tocopherol than that of C lambs on the same intake and by day 6 in MAP (75%O2/25%CO2) chroma and a* were below acceptable levels in C30 lambs. TBARS were higher in C30 and C60 muscle than in other treatments (P < 0.001) after 3 and 6 days display. Muscle fatty acid composition varied with basal diet but lipid oxidation depended more on vitamin E concentration with an initial concentration of 1.9 μg/g muscle preventing significant lipid oxidation.     

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.     

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).     

Particle size analysis of lamb meat: Effect of homogenization speed, comparison with myofibrillar fragmentation index and its relationship with shear force

The impact of homogenization speed on Particle Size (PS) results was examined using samples from the M. longissimus thoracis et lumborum (LL) of 40 lambs. One gram duplicate samples from meat aged for 1 and 5 days were homogenized at five different speeds; 11,000, 13,000, 16,000, 19,000 and 22,000 rpm. In addition to this LL samples from 30 different lamb carcases also aged for 1 and 5 days were used to study the comparison between PS and myofibrillar fragmentation index (MFI) values. In this case, 1 g duplicate samples (n = 30) were homogenized at 16,000 rpm and the other half (0.5 g samples) at 11,000 rpm (n = 30). The homogenates were then subjected to respective combinations of treatments which included either PS analysis or the determination of MFI, both with or without three cycles of centrifugation. All 140 samples of LL included 65 g blocks for subsequent shear force (SF) testing. Homogenization at 16,000 rpm provided the greatest ability to detect ageing differences for particle size between samples aged for 1 and 5 days. Particle size at the 25% quantile provided the best result for detecting differences due to ageing. It was observed that as ageing increased the mean PS decreased and was significantly (P < 0.001) less for 5 days aged samples compared to 1 day aged samples, while MFI values significantly increased (P < 0.001) as ageing period increased. When comparing the PS and MFI methods it became apparent that, as opposed to the MFI method, there was a greater coefficient of variation for the PS method which warranted a quality assurance system. Given this requirement and examination of the mean, standard deviation and the 25% quantile for PS data it was concluded that three cycles of centrifugation were not necessary and this also applied to the MFI method. There were significant correlations (P < 0.001) within the same lamb loin sample aged for a given period between mean MFI and mean PS (−0.53), mean MFI and mean SF (−0.38) and mean PS and mean SF (0.23). It was concluded that PS analysis offers significant potential for streamlining determination of myofibrillar degradation when samples are measured after homogenization at 16,000 rpm with no centrifugation.