An evaluation of current and alternative systems for quality grading carcasses of mature slaughter cows

Strip loins from 354 female bovine carcasses, selected to represent 30 skeletal maturity (A, B, C, D, and E) x marbling score (SA/MA/AB, MD, MT, SM, SL, and TR/PD) subclasses, were used to evaluate current and alternative systems for classifying cow carcasses into expected-palatability groups. Strip loins were vacuum-packaged, stored for 14 d postmortem at 2 degrees C, and frozen (-27 degrees C). Five steaks from each strip loin, each cooked to a different internal temperature (60, 66, 71, 77, or 82 degrees C), were used for shear force determinations. Two steaks from each strip loin, one cooked to 66 degrees C and the other to 77 degrees C, were used for sensory evaluation. Increased carcass maturity was associated with decreased tenderness and juiciness, increased flavor intensity, and a higher incidence of flavors described as "painty," "fishy," and "grassy." Position of a carcass within a maturity group had a negligible effect on palatability. Increased marbling was associated with greater tenderness and juiciness, a lower incidence of steaks with a "grassy" flavor, and a higher incidence of steaks with a flavor described as "fatty." Relationships between marbling and beef palatability traits were consistent across all maturity groups. Carcasses of maturities A through E were most effectively stratified according to differences in palatability when marbling scores were grouped as follows: 1) MD and higher; 2) SL, SM, MT; and 3) TR/PD. Among mature (C, D, and E maturity) carcasses, yellow-colored fat was associated with greater beef toughness and higher detection rates for "grassy" and "fishy" flavors. Higher end-point temperatures were associated with higher shear force values and lower ratings for muscle fiber tenderness, connective tissue amount, overall tenderness, and juiciness. Two alternative grading approaches (one involving current quality grading factors and the other involving the use of fat color as an additional grade factor) were developed for possible use in classification of cow carcasses into expected-palatability groups. Both alternative systems provided a more effective stratification of cow carcasses according to palatability differences than did the current USDA quality grading system.

On-line pork carcass grading with the Autofom ultrasound system

On-line pork carcass grading with the Autofom ultrasound system is described. The system consists of 16 ultrasound transducers positioned in a frame. The carcass is measured fully automatically at 3,200 positions to a depth of approximately 12 cm with a depth resolution of .19 mm. The ultrasound data form a three-dimensional ultrasound image, which is processed for noise reduction, orientation detection, and extraction of 127 features describing the carcass composition. The image features are used in a multivariate regression model, that is used for on-line predictions. On-line tests performed at line speeds up to 1,150 carcasses/h provide predictions of the meat percentage with an accuracy of 1.58 to 1.95%. Good predictions of the fat thickness and primal meat cuts have also been made.

Beef customer satisfaction: role of cut, USDA quality grade, and city on in-home consumer ratings

An in-home beef study evaluated consumer ratings from moderate-to-heavy beef users as influenced by cut (top loin, top sirloin, and top round steaks), USDA quality grade (Top Choice, Low Choice, High Select, and Low Select), and city (Chicago, Houston, Philadelphia, and San Francisco). Consumers (n = 2,212) evaluated each steak for overall like (OLIKE), tenderness (TEND), juiciness (JUIC), flavor desirability (DFLAV), and flavor intensity (IFLAV) using 23-point hedonic scales (23 = like extremely, extremely tender, extremely juicy, like extremely, and an extreme amount of flavor; 1 = dislike extremely, not at all tender, not at all juicy, dislike extremely, and no flavor at all). A USDA grade x cut interaction existed for OLIKE (P < .05). Consumers rated top loin steaks highest (P < .05) in OLIKE and ranked Top Choice highest of all steaks (P < .05). Within the top loin, consumers were not (P > .05) able to distinguish OLIKE differences between Low Choice and High Select or between High Select and Low Select. For OLIKE, top sirloin was rated intermediate (P < .05) of the three cuts, and consumers were not able to detect (P > .05) USDA quality grade differences. For OLIKE, top round was the lowest-rated (P < .05) cut. However, consumers preferred (OLIKE, P < .05) Top Choice to the other USDA grades offered. Grade and city interacted to affect TEND, JUIC, DFLAV, and IFLAV. The cut x city interaction was significant for all palatability attributes. Cut and city affected customer satisfaction more than USDA quality grade. Tenderness and flavor were important and equal contributors to OLIKE, r = .85 and r = .86, respectively.

Rapid species identification in meat by using satellite DNA probes

A fast procedure for species identification in heated meat is described. Deoxyribonucleic acid (DNA) was isolated from meat samples by an alkaline extraction method and hybridized to a conjugate of a specific oligonucleotide and alkaline phosphatase. The oligonucleotide probes are based on satellite DNA, tandem-repeated sequences, which are highly specific for species. Probes are developed for the identification of meat from cattle, sheep/goat, horse, deer, pig, chicken and turkey. Differentiation between closely related species like chicken and turkey is possible. Admixtures of 1-5% of meat of one species in another could be detected. The complete assay of up to 50 samples takes 4 h. Heated meat samples could be analysed.

Evaluation of a method for colour classification of veal

In the Netherlands veal carcasses are classified according to colour with the aid of a colour scale. The colour scale, existing of five coloured chips, and the results of its application in the classification system were evaluated both theoretically and practically. The result was that theoretically 75% of the samples were assigned to the same and 25% to a different colour class when assessed by two people. In practice the standardized colour classification of veal in the Netherlands is carried out 45 min post mortem by an independent organization, the 'Centraal Bureau voor Slachtveediensten' (CBS). The correlation coefficient of the results of parallel classifications of 12,659 carcasses between CBS employees and inspectors was 0.88. The CBS employees assigned 80.1% of the carcasses to the same colour class, 10.5% to a colour that was one class lighter and 9.4% to a colour that was one class darker than the inspectors did. It is concluded that high reproducibility and comparability can be achieved uniform implementation of a visual colour classification system.

Characteristics of the carcases and meat of slaughtered calves as indicators of 'immaturity'

Arbitrary age limits and offal weights are often used to classify meat and offals from 'bobby' calves as 'immature' and hence unfit for human consumption. Such age limits were not scientifically validated in a comparative study of the ante mortem characteristics, and the physical characteristics of the carcases and offals of groups of Jersey calves aged one, five, 14 and 21 days. The quality characteristics of muscle (pH and water-holding capacity) did not change with increasing age, and the changes in chemical composition (water, protein, fat and ash) were minimal, particularly between the five-day-old and 21-day-old groups. Small changes in muscle colour measured objectively were not detectable visually.

Effects of sexual condition and age on carcass characteristics and grading of Sussex cattle in Zimbabwe

The effects of sexual condition and age at slaughter on carcass characteristics were investigated in Sussex cattle. At three months of age 93 male calves were allocated to three sexual treatments: entire, cryptorchid and castrate. The cattle were weaned at eight months, grazed on range and then placed into feedlots for 90 days prior to slaughter at 15, 18 or 21 months of age. Entire and cryptorchid cattle gained more (P < 0.01) weight and had heavier and learner carcasses than the castrates. Although cattle slaughtered at 15 months of age had better fleshing grades than those slaughtered at 18 or 21 months of age, no animal was down-graded for exhibiting marked secondary sexual characteristics.

What's in a burger?

In an attempt to confirm the presence or absence of central nervous tissue in commercially prepared beefburgers, four burgers were processed and stained using routine histological laboratory techniques. Constituent parts of the burgers could be identified readily. In this small sample no central nervous tissue was found. There is currently considerable general interest in the contents of foodstuffs, particularly now that certain specified bovine offals as well as central nervous tissue have been banned from human consumption. Conventional histological techniques may be of value in analysing the ingredients of beef products.

[Incidence of various disorders in fattening pigs and their effects on growth and carcass quality]

Findings in 6,304 fattening pigs at the experimental piggery 'Zuid-West Nederland' in Sterksel were used to study the incidence of tail-biting, leg disorders, cough and diarrhoea. The majority of animals were fed ad libitum and housed on completely or partially slatted floors. Approximately 20 per cent of the animals were treated for various conditions. The appearance of these conditions was associated with a decrease in rate of gain of 10-67 g day-1 animal-1. Carcass grading was also reduced in the animals, which had been treated for affections. Tail-biting and diarrhoea were the two most common conditions. The majority of conditions occurred mainly during the first eighty days of the fattening period. However, a higher relative proportion of animals were treated for cough during the last fourty days of the fattening period. Leg-disorders affected the rate of gain more than did the other conditions. The rate of gain was reduced by 67 g day-1 animal-1 and carcass grading by 11 per cent. The conditions were associated with considerable loss in production traits (gain and carcass grading).

Differentiation of meat according to species by the electrophoretic separation of muscle lactate dehydrogenase and esterase isoenzymes and isoelectric focusing of soluble muscle proteins

Species identification of fresh meat can be readily achieved by serological techniques with the limitation that closely related species, such as sheep/goat, cattle/buffalo and horse/donkey, cannot be differentiated. We have examined electrophoretic techniques with particular reference to the identification of meat from closely related species. The results showed that beef and buffalo meat and meat from red and grey kangaroos could be clearly distinguished by isoelectric focusing on polyacrylamide gel or agarose in the pH range 5.5 to 8.5. Sheep and goat meat, and horse and donkey meat could not be differentiated by this technique, but were clearly distinguished from each other by their esterase isoenzyme profiles obtained after electrophoretic separation on cellulosic membrane strips. Results from this latter technique were available in one hour. We believe that species identification of fresh meat should involve an initial screening test by serological techniques followed by confirmation of the identity of suspect samples by electrophoretic techniques.

Identification of species in cooked crabmeat by thin layer isoelectric focusing

Thin layer polyacrylamide gel isoelectric focusing (TLIEF) is described for characterizing the species-specific, heat-denatured proteins of 8 species of crab: red (Geryon quinquedens), rock (Cancer irroratus), Jonah (Cancer borealis), blue (Callinectes sapidus), king (Paralithodes camtschatica), snow (Chionoectes spp.), European edible (Cancer pagurus), and dungeness (Cancer magister). Protein pattern differences are shown not only among species, but also between 2 modes of heat processing of the crabmeat. Individual variation within the species as to sex, size and maturity, length of frozen storage, and body parts chosen for sampling do not alter the species banding pattern. The reproducible species-specific fingerprint obviates the need to analyze authenticated samples simultaneously with the unknown crabmeat.