Tough Steaks Research Articles

Metabolomic Investigation of Tenderness and Aging Response in Beef Longissimus Steaks

A study was conducted to identify molecular changes reflective of beef tenderness variation and tenderization during postmortem aging. Carcasses (U.S. Select) were selected to represent extremes in tenderness (n = 20; 10 per class). Two pairs of adjacent longissimus lumborum steaks from each strip loin were blocked by location and assigned to each aging time (2, 7, 14, or 28 d postmortem). One steak from each pair was designated for slice shear force determination and the other was used for sarcomere length, western blotting for desmin, and non-targeted LC- and GC–MS metabolite profiling. Tough steaks had higher (P < 0.001) slice shear force values than tender steaks, and increasing aging time decreased (P < 0.001) slice shear force values. Tender steaks had a greater (P < 10–4) proportion of desmin degraded than tough steaks, and increasing aging time increased (P < 10–22) desmin degradation in steaks from both classes. From 2,562 profiled metabolites, 102 metabolites were included in the final analysis after statistical screening. Twenty-eight metabolites could be annotated and loosely categorized into amino acids/peptides (n = 16), metabolism intermediates (n = 7), glycosides (n = 4), and fatty acids and phospholipids (n = 3). Amino acids were primarily associated with desmin degradation. Increased glucose levels were strongly associated to the tender classification and moderately associated to increased proteolysis, while increased glucose-6-phosphate was strongly related to the tender class but was related to decreased proteolysis. Increased malic acid was strongly associated to the tough classification, increased slice shear force, and decreased proteolysis. Increased levels of 3-phosphoglyceric acid and glycerol-3-phosphate was moderately associated with increased slice shear force and decreased proteolysis. These data indicate that accumulation of amino acids during aging is strongly related to postmortem proteolysis and may provide evidence of the fate of proteins degraded postmortem. Measures of glucose, glucose-6-phosphate, and malic acid concentrations may provide a metabolic fingerprint indicative of tenderness differences in beef longissimus.

CAPN1, CAST, and DGAT1 genetic effects on preweaning performance, carcass quality traits, and residual variance of tenderness in a beef cattle population selected for haplotype and allele equalization1,2,3,4

Genetic marker effects and type of inheritance are estimated with poor precision when minor marker allele frequencies are low. A stable composite population (MARC III) was subjected to marker-assisted selection for multiple years to equalize specific marker frequencies to 1) estimate effect size and mode of inheritance for previously reported SNP on targeted beef carcass quality traits (n=254), 2) estimate pleiotropic effects of previously reported SNP on nontarget performance traits (n=542 or 254), and 3) evaluate tenderness SNP specific residual variance for LM tenderness. Three haplotypes within μ-calpain (CAPN1), a SNP in calpastatin (CAST), and a dinucleotide substitution in diacylglycerol O-acyltransferase 1 (DGAT1) were successfully selected to equalize their frequencies. Traits evaluated were birth BW, weaning BW, yearling BW, final BW, dressing percent, HCW, fat thickness, LM area, USDA marbling score, yield grade, LM slice shear force (SSF), and visible and near-infrared (VISNIR)-predicted SSF. While the CAPN1 genotype effect on SSF was not significant (P=0.12), the direction and size of CAPN1 contrasts were consistent with previous research. Effects on SSF between divergent CAPN1 haplotypes (1.153 kg) and the additive effect of CAST (0.902 kg) were large, and animals homozygous for tender alleles at both CAPN1 and CAST would have 4.11 kg lower SSF (27.5% of the mean) than animals homozygous tough for both markers. Furthermore, the interaction between CAPN1 and CAST for SSF was not significant (P=0.40). There were significant effects for DGAT1 on adjusted fat thickness (P=0.02) and VISNIR-predicted SSF (P<0.001) with additive and dominance modes of inheritance (P<0.05) for both traits. Furthermore, CAST genotype specific residual variance models fit significantly better (P<0.001) than single residual variance models for SSF, with the tougher genotypes having progressively larger residual (and hence phenotypic) variances. Therefore, risk of a tough steak from the undesired CAST genotype is increased through both an increase in mean and an increase in variation. This work is supportive of the importance of CAPN1 and CAST for mean tenderness in beef, confirms an effect of CAST on beef LM tenderness variation, and identifies an effect of DGAT1 on subcutaneous fat thickness.

µ-Calpain, calpastatin, and growth hormone receptor genetic effects on preweaning performance, carcass quality traits, and residual variance of tenderness in Angus cattle selected to increase minor haplotype and allele frequencies1,2,3

Genetic marker effects and interactions are estimated with poor precision when minor marker allele frequencies are low. An Angus population was subjected to marker assisted selection for multiple years to increase divergent haplotype and minor marker allele frequencies to 1) estimate effect size and mode of inheritance for previously reported SNP on targeted beef carcass quality traits; 2) estimate effects of previously reported SNP on nontarget performance traits; and 3) evaluate tenderness SNP specific residual variance models compared to a single residual variance model for tenderness. Divergent haplotypes within µ-calpain (CAPN1), and SNP within calpastatin (CAST) and growth hormone receptor (GHR) were successfully selected to increase their frequencies. Traits evaluated were birth BW, weaning BW, final BW, fat thickness, LM area, USDA marbling score, yield grade, slice shear force (SSF), and visible and near infrared predicted slice shear force. Both CAPN1 and CAST exhibited additive (P < 0.001) modes of inheritance for SSF and neither exhibited dominance (P ≥ 0.19). Furthermore, the interaction between CAPN1 and CAST for SSF was not significant (P = 0.55). Estimated additive effects of CAPN1 (1.049 kg) and CAST (1.257 kg) on SSF were large in this study. Animals homozygous for tender alleles at both CAPN1 and CAST would have 4.61 kg lower SSF (38.6% of the mean) than animals homozygous tough for both markers. There was also an effect of CAST on yield grade (P < 0.02). The tender CAST allele was associated with more red meat yield and less trimmable fat. There were no significant effects (P ≥ 0.23) for GHR on any of the traits evaluated in this study. Furthermore, CAST specific residual variance models were found to fit significantly better (P < 0.001) than single residual variance models for SSF, with the tougher genotypes having larger residual variance. Thus, the risk of a tough steak from the undesired CAST genotype is increased through both an increase in mean and an increase in variation. This work confirms the importance of CAPN1 and CAST for tenderness in beef, provides a new effect of CAST on beef tenderness, and questions the utility of GHR as a selection marker for beef quality.

The Paradox of Toughening During the Aging of Tender Steaks

ABSTRACT: Aging is the practice of holding meat at low temperatures to improve tenderness that is the most important sensory attribute affecting consumer acceptability of beef. Because of the inconsistencies in measured tenderness changes during aging, we attempted to look at the relationship between aging and initial tenderness irrespective of animal age, genetics, or nutritional status. Cattle were selected to represent a full range of quality grades from Utility to Prime. Steaks from these cattle were aged in vacuum bags for 0, 7, or 14 d and tenderness characteristics were assessed. Steaks were cut from the frozen loin sections, thawed, and cooked on open hearth grills to 70 °C. Sensory evaluation was completed by a 6‐member trained sensory evaluation panel and Warner‐Bratzler shear was determined. The average shear values decreased with aging time across most grade categories; however, improvement was not uniform. Steaks from Utility grade cattle improved the most while steaks of other grades improved less. Shear values overlapped a great deal across all grades and to gain a better understanding of changes with aging, steaks were grouped based on initial shear value differences of 1 kg. Shear value of the toughest steaks decreased the most during aging (−36%), while those with the lowest shear values increased (16%). The same pattern emerged when steaks were grouped by initial tenderness. These results suggest that initially tough steaks will benefit from aging while very tender steaks may be adversely affected.

Brazilian consumers' perception of tenderness of beef steaks classified by shear force and taste

The knowledge of consumer perception of meat tenderness and taste is essential to forecast a Brazilian quality value-based beef market. This study aimed to verify perception of tender (WBSF &lt; 4.1 kg) from tough (&gt; 4.8 kg) strip loin steak or uncharacteristic (calcium-treated/Ca-IM) and normal (non-calcium/NO-Ca) meat taste by consumers according to gender, age, education and income levels. Steaks were previously classified by shear force measurements as tender or tough. Each consumer was served a paired sample of one tender and of one tough steak, which were either Ca-IM or NO-Ca treated before tenderness classification. Three hundred and eight consumers answered a nine-point intensity (tenderness) and hedonic (taste) scales evaluation questionnaire. Among consumers, 82.2% indicated beef as first choice meat products, 75.3% had beef at least four times a week; 39.3% considered taste as the most important meat attribute and 30.2% considered tenderness; 75.8% were males; 73.6% were 21 to 55 years old; 56.7% had college education; 76.6% had monthly income higher than US $ 435,00. Tender steaks were scored highest (P &lt; 0.01), independently of gender, age and income. However, elderly consumers gave higher scores to tender steaks in comparison to middle age consumers (P &lt; 0.05). In the lower education level, scores given to tender and tough meat did not differ. The higher income level responders assigned lower tenderness scores within tender or tough meat (P = 0.10). Differences in taste were perceived by both genders, and by consumers in every income and education level. Males gave higher scores (dislike less) within Ca-IM steaks. Consumers in the lower education level scored taste higher (like most) within untreated samples. The elderly people could not differentiate taste between the Ca-IM and NO-Ca steaks. These are the first indications that Brazilian consumers perceive tender from tough or uncharacteristic taste of beef, but palatability is evaluated differentially depending on gender, age, education and income level.

Association of a single nucleotide polymorphism in the calpastatin gene with carcass and meat quality traits of beef cattle1

Calpastatin (CAST) is a naturally occurring protein that inhibits the normal tenderization of meat as it ages postmortem. A SNP was identified in the CAST gene (a G to C substitution) and genotyped on crossbred commercially fed heifers (n = 163), steers (n = 226), and bulls (n = 61) from beef feedlots, and steers (n = 178) from a University of Guelph feeding trial. The association of the CAST SNP with carcass and meat quality traits was studied. Carcass traits included fat, lean, and bone yield; grade fat; LM area; and HCW. Meat quality traits included marbling grade; i.m. fat content of LM; tenderness evaluation of LM (Warner-Bratzler shear force) at 2, 7, 14, and 21 d of postmortem aging; and tenderness evaluation of semitendinosus muscle at 7 d of postmortem aging. The mixed model used in the analyses included fixed effects of CAST genotype, sex, slaughter group, and breed composition (linear covariate); sire was a random effect. For the analysis of shear force, i.m. fat content of LM was also included in the model as a linear covariate. Shear force measures were analyzed within days of postmortem aging and by repeated measures analysis. The CAST SNP allele C was more frequent (63%) in the crossbred population than allele G. The CAST SNP was associated with shear force across days of postmortem aging (P = 0.005); genotype CC yielded beef that was more tender than GG (-0.32 kg +/- 0.13), and CG had intermediate tenderness. The corresponding average allele substitution effect (G to C substitution) was also highly significant (-0.15 +/- 0.05 kg, P = 0.002). A lower percentage of unacceptably tough steaks (shear force > 5.7 kg) at 2 and 7 d postmortem was associated with an increasing number of C alleles (P < or = 0.05). At 7 d postmortem, the percentage of unacceptably tough steaks decreased by 24 and 35%, respectively, for animals carrying 1 and 2 copies of the C allele relative to animals with no C alleles. However, genotype CC had a greater fat yield (+1.44 +/- 0.56%; P = 0.037) than genotype GG, with a corresponding allele substitution effect of 0.67 +/- 0.27% (P = 0.015). Therefore, the CAST SNP allele C was associated with increased LM tenderness across days of postmortem aging and, importantly for the beef industry, had a significant reduction in the percentage of steaks rated unacceptably tough by consumers based on an assumed threshold level.

Effectiveness of the SmartMV prototype BeefCam System to sort beef carcasses into expected palatability groups1

This study was conducted to determine the effectiveness of the SmartMV prototype BeefCam Video Imaging System (prototype BeefCam) for classifying beef carcasses into palatability ("certified" or "not certified" as palatable) groups. Carcasses (n = 769) were selected from four beef-packing plants to represent three USDA quality grade groups (Top Choice, TC; Low Choice, LC; and Select, SE). Following chilling, a prototype BeefCam image of the longissimus muscle was obtained for each carcass. Strip loins were collected from the left side of each carcass and aged for 10 d; Warner-Bratzler shear force (WBSF; n = 769) values and consumer panel ratings (hedonic, end-anchored, 9-point ratings for overall like/dislike; n = 500 carcasses) were obtained for cooked steaks. Using information from the images, two regression models were developed to predict the first principal component of WBSF and consumer panel ratings for sorting carcasses based on expected eating quality. Model I used only prototype BeefCam output, whereas Model II used prototype BeefCam output and a coded value for quality grade group. For both models, carcasses with a predicted value of less than 0.0 were certified as producing palatable beef Additional carcasses (n = 292) were evaluated at a fifth and separate packing plant by prototype BeefCam to validate Models I and II. A strip loin was collected from each carcass and WBSF was measured after 14 d of aging. The percentages of validation carcasses that generated tough (WBSF > or = 4.5 kg) steaks were 6.5,5.8,10.7, and 7.9% for, TC, LC, SE, and all carcasses, respectively. Use of Model I certified 51.9, 47.6, 43.8, and 47.3% of TC, LC, SE, and all carcasses, respectively. Of the carcasses certified by use of Model I, 0.0,0.0, 4.1, and 1.4% of TC, LC, SE, and all carcasses, respectively, generated tough steaks. Use of Model II certified 59.7, 47.6, 25.0, and 42.1% of TC, LC, SE, and all carcasses, respectively. Of the carcasses certified by use of Model II, 2.2, 0.0, 3.6, and 1.6% of TC, LC, SE, and all carcasses, respectively, generated tough steaks. For both models, the frequency of carcasses that produced tough steaks in the certified group was lower (P < 0.05) for all validation carcasses sampled compared with that of the original carcass population. Based on the decrease in the frequency of carcasses that produced tough steaks, further development of a commercial BeefCam system is warranted.

The influence of chilling rate and fat cover on beef quality

The economic advantages of rapid carcass chilling include reduced cooling time, increased carcass processing rate, and decreased shrink and drip losses; however, it may also reduce subsequent meat tenderness, especially in lean carcasses. The present study examined the effects of blast chilling and electrical stimulation on quality of longissimus lumborum (LL) and semimembranosus muscles from carcasses with a wide range in backfat thickness (0 to 69 mm). Despite promoting a wide range in postmortem pH and temperature decline, backfat thickness had a limited effect on meat quality. There was a decrease in the proportion of carcasses with very high (&gt;35 N cm–2) shear values and a tendency (P = 0.12) for the average shear force to decrease in the LL as backfat depth increased. Unexpectedly, leaner carcasses had less shrink loss than fatter carcasses under blast chill conditions. While blast chilling resulted in slightly darker, tougher meat, electrical stimulation was able to reduce these effects. Neither early postmortem pH nor temperature at 10 h was clearly associated with a pattern in shear force, although high pH10 was associated with tough steaks. Blast chilling in combination with electrical stimulation can be recommended to industry as a means to reduce chilling times and shrink losses while producing meat quality that is as good as, or slightly superior to conventionally cooled carcasses. Key words: Beef quality, blast chilling, electrical stimulation, fat thickness

In‐Store Valuation of Steak Tenderness

AbstractExperimental methods were used to examine consumer willingness‐to‐pay for steak tenderness in a grocery store setting. When relying on a taste test alone to determine product quality, the participants paid an average premium of $‐1.23/lb for a tender versus tough steak. Fifty‐one percent of the participants were willing to pay an average of $‐1.84/lb when they had completed a taste test and were also provided information about the steak's tenderness. Results indicate that most consumers prefer more tender steaks and that many are willing to pay a premium for tender steaks.

Neural network modeling of carcass measurements to predict beef tenderness

Neural network (NN) models were developed for predicting and classifying an objective measurement of tenderness using carcass data such as pre-slaughter information (sex, age, kill order), weights, pH, temperatures, lean color readings, lab-determined measurements, grade measurements and organ weights. Tenderness was expressed objectively as Warner-Bratzler shear (WBS) force measured on steaks, aged 6 d, from the longissimus thoracis et lumborum (LTL) muscle. Carcass data from experiments conducted between 1985 and 1995 at the Lacombe Research Centre were combined to form large data sets (n = 775–1177) for modeling. Neural network models to predict actual shear values showed limited potential (R2 = 0.37–0.45) and were only marginally better than a multiple linear regression (MLR) model (R2 = 0.34). Neural network models that classified carcasses into tenderness categories showed better potential (mean accuracy 51–53%). The best four-category (tender, probably tender, probably tough, tough) model classified tender and tough steaks with accuracies of 0.64 and 0.79, respectively. This model reduced tough and probably tough carcasses by 55% in our population. The model required the following 11 inputs, which, except for cooking method, are available by 24 h postmortem: sex, live plant weight, hot carcass weight, 24-h cooler shrink, 24-h pH, 24-h CIE color b*, 24-h CIE lightness L* × hue angle, rib eye area, grader's marbling score (AMSA%), grade, and cooking method. By implementing techniques outlined in this study in a plant situation, the current 23% unacceptable consumer rating for Canadian beef could be reduced to 10–12%. Key words: Neural networks, beef, tenderness, carcass measurements, longissimus muscle

Near-infrared reflectance analysis for predicting beef longissimus tenderness.

Near-infrared reflectance spectra (1,100 to 2,498 nm) were collected on beef longissimus thoracis steaks for the purpose of establishing the feasibility of predicting meat tenderness by spectroscopy. Partial least squares (PLS) analysis (up to 20 factors) and multiple linear regression (MLR) were used to predict cooked longissimus Warner-Bratzler shear (WBS) force values from spectra of steaks from 119 beef carcasses. Modeling used the combination of log(1/R) and its second derivative. Overall, absorption was higher for extremely tough steaks than for tender steaks. This was particularly true at wavelengths between 1,100 and 1,350 nm. For PLS regression, optimal model conditions (R2 = .67; SEC = 1.2 kg) occurred with six PLS factors. When the PLS model was tested against the validation subset, similar performance was obtained (R2 = .63; SEP = 1.3 kg) and bias was small (<.3 kg). Among the 39 samples in the validation data set, 48.7, 87.7, and 97.4% of the samples were predicted within 1.0, 2.0, and 3.0 kg, respectively, of the observed Warner-Bratzler shear force value. The optimal PLS model was able to predict whether a steak would have a Warner-Bratzler shear force value < 6 kg with 75% accuracy. The R2 of MLR model was .67, and 89% of samples were correctly classified (< 6 vs > 6 kg) for Warner-Bratzler shear force. These data indicate that NIR is capable of predicting Warner-Bratzler shear force values of longissimus steaks. Refinement of this technique may allow nondestructive measurement of beef longissimus at the processing plant level.

Forty years on.

It was 10 00 am and John Smith, BMedSci (Open University), MB (Harvey School of Medicine), FRCS (UK), MD, PhD (Scunthorpe), was very bored. He had tried to spin out his morning list but had been unable to pretend that his first case, a dermoid, was anything but simple. Worth a frozen section though, you could never be too careful. He was taking a respite before the last remaining operation and had left his senior registrar to close the wound and registrar to apply the povidone dressing. As the decaffeinated coffee arrived through the wall hatch there was time for reflection. What would he do with himself when he retired next year At 50 he might live another 60 years. He flipped a Mannitol spansule into the drink to ease his congested nose. It could not be any more dull than at present though. After all, there was very little left to operate on. As a student he had seen some of the very last cases of peptic ulc?ration, the addition of cimetidine to the water supply had seen to that. Nursery school bran had replaced cod liver oil, and this had made extinct most diseases of the large bowel. As a houseman he could just remember the theatre crowded with excited observers as a blustering Sir Heneage Hopkinson explored a diverticular abscess. It's 10 years since I last saw one of these! he extolled, gleefully splashing the pus about. Pass the sucker please, nursey. what, Sir ? Of course medical research had a lot to answer for. He pontificated with some anguish and had to shift the weight off his chrome-cobalt ischial tuberosity acquired after a mishap on a Space Shuttle package holiday. Regrettably nearly all disease could be treated medically or simply prevented from even occurring. He mused over some scientific milestones. The latter day scourges of blackheads, baldness, piles, and halitosis had all met with their respective cures, severely diminishing waiting lists and general practitioners' surgeries. Interferon had seen off practically all infections, even the common cold. Gall stones could be dissolved in a few hours with a simple tablet. Cancer melted away with Rubean. This derivative of runner bean had been discovered by pure chance. A laboratory technician had been surreptitiously eating his lunch near a tumour tissue culture and, as his knife skidded across the plate on cutting his tough steak, a piece of runner bean fell in. He hid the bottle. Some days later the culture was found to be dead, and the terrified technician became famous. Atheroma was certainly caused by cigarettes but its severity did not fall when imitation tobacco was made compulsory. Of course it didn't, the causative agent was in the paper. Cigarettes were now made of shredded tobacco glued into columns and very nice they were too. There was so little trauma. Private transport had recently been abolished, and the safety record of the State system was 100%. There was no street violence as there were simply no streets. Mental illness had vanished with the addition of endorphin to table salt. Fortunately, it was stable with iodine, magnesium, caffeine, and stilboestrol. Irony furrowed his brow and dimpled his cheeks. Here he was being rueful about his present lot when he was partly responsible for vanquishing appendicitis. His friend Arnold had really cracked it though, one of the last great unknowns of medical science had yielded its secrets. For some years Arnold's exclusive task had been to delineate the cause of appendicitis and he had found it. The application of an epsilon-squared Pupil's S test had proved it conclusively. He relived the secretive childish titter he had enjoyed as he had enumerated the previous incriminations: tobacco inevitably, autoimmune inflammation, aspirin, and salami rind. Nor was it lack of bran. Of course, Africans emigrating to the United States increased their incidence of appendicitis but it wasn't the fibre. Oh no, it was the talcum powder. And that was why it was commoner in children: mothers smothering their kiddies in the stuff. To think, from then on every container had to carry a government health warning. With sadness he recalled bidding Arnold farewell. No longer needed, Arnold, a computer, was switched off, closing down his memory banks forever.