Comparison of some properties of meat from normal steers and steers heterozygous for muscular hypertrophy

Carcase characteristics and meat properties of 19 normal steers and 14 steers heterozygous for muscular hypertrophy (HMH), killed at a liveweight of circa 360 kg and 500 days of age, were compared. Carcases of the HMH animals had less subcutaneous fat and a greater eye muscle area. It was considered that HMH animals were no more stress susceptible than control animals as plasma glucose concentrations at slaughter and ultimate pH values of the M. semitendinosus (ST) did not differ. ST sarcomere length and cooking losses did not differ between control and HMH animals. ST Warner-Bratzler (peak) shear force values and adhesion values were less in the HMH animals; these lower values would indicate that the ST of the HMH animals was more tender. These differences may have resulted from the difference in the mean age of the normal (527 days) and the HMH groups (489 days) at slaughter. However, other workers have found a reduced hydroxyproline content in muscles of homozygous double-muscled animals and the lower adhesion values of animals heterozygous for muscular hypertrophy may reflect the fact that they also have a lower connective tissue content in their muscles compared with normal animals.     

The preference of the consumer for pork from homozygous or heterozygous halothane negative animals

To evaluate the taste preference of the consumer for meat from homozygous (NN) halothane negative pigs or heterozygous (Nn) halothane negative pigs, a consumer test was conducted at the "Agriflora" exhibition, concerning Flemish agriculture and horticulture, held from 8 to 10 January 1999 in Ghent, Belgium. The carcass quality of both tested genotypes was similar, while acidity, colour and drip loss were inferior and cooking loss and Warner-Bratzler shear force superior for the Nn pigs compared with the NN pigs. One hundred and seventy-one visitors completed the test correctly. No significant difference was found between NN- and Nn-meat for the tastiness scores. These results do suggest that elimination of the halothane gene from the pig population does not guarantee a better eating quality of the meat.     

Effects of using plum puree on some properties of low fat beef patties

The purpose of this study was to determine the effects of using different amounts of plum puree (5%, 10% or 15%) on some properties of low fat beef patties. Plum puree (PP) was used as an extender in beef patties. Moisture content decreased with increasing concentration of plum puree. Increasing amounts of PP decreased beef patty pH. The highest cooking yield and moisture retention were found in 5% PP samples. Diameter reduction increased and thickness reduction decreased with increasing amounts of PP. The addition of PP to the formulation significantly affected the colour of samples. TBARS values of control samples were higher than in PP added samples at the end of the storage period. Higher PP concentrations in the formulations led to increased juiciness and texture scores. The results indicated that 5% or 10% plum puree can be used as an extender in low fat beef patties.     

The tenderness of cooked and raw meat from young and old beef animals

The shortening-toughness relationships for sternomandibularis muscles of young ox and large old bull have been compared. In both, toughness, measured by tenderometer, increases to a maximum at a shortening of 40%, and declines steeply from there at higher shortenings. This characteristic peaked relationship is obtained for ox and bull cooked both at 60 and 80 °C. However, toughness values for meat cooked to 60 °C are only about half those for meat cooked to 80 °C. In contrast to these similarities in the relationships for young and old animals, the rate of toughness increase with shortening in ox is considerably less than in bull. Thus toughness of ox at a given shortening and cooking temperature is considerably lower than that for bull, especially at high shortenings. A further distinction is made between the animals in that raw ox muscle does not give a peaked shortening-toughness relationship, whereas raw old bull does. The results have shown that for longissimus and sternomandibularis muscles a trained taste panel is only sensitive to variations in toughness in the lower half of the range of shear force values determined by tenderometer. In the light of this, live animal characteristics and muscle shortening are both important in determining toughness measured by taste panel.     

Cooking beef joints from the frozen or thawed state

A comparative experimental study of cooking 2.25 kg beef joints from the frozen state with and without preliminary thawing has been made with respect to cooking times and losses, energy requirements and sensory differences. The cooking times and energy requirements of the joints cooked directly from ? 20°C were greater than those first thawed to 20°C by a factor of up to 2.3. No significant difference in cooking losses or juiciness was detected between the treatments; however, a statistically significant difference was found in the texture of samples cooked directly from frozen (mean ?0.8) and those previously thawed (mean +0.2). Samples cooked inside a roasting bag (moist heat) were also found to be significantly tougher than those cooked in an open tray (dry heat) the means being ?0.7 and +0.1 respectively, the texture being assessed on an eight point scale (+7 extremely tender to ?7 extremely tough) in each case.     

The elastin content of various muscles of beef animals

The elastin content of various muscles of beef animals has been measured by a technique designed to remove the last traces of collagen and myofibrillar proteins. Amino acid analysis of the elastin prepared in this way is almost identical with that of purified elastin from ox ligamentum nuchae. In particular, the hydroxyproline values of each are less than 2% of the dry weight. Most of the choice cuts of meat from the hindquarter and loin contain less than 0.2% elastin on the dry weight basis, i.e. less than 5% of the total connective tissue. The M. semitendinosus is the chief exception found. It contains about 2% dry fat free solids (DFFS), i.e. about 40% of the connective tissue. In the forequarter, the latissimus dorsi is the only muscle which contains as much elastin as the semitendinosus, i.e. about 2.0% DFFS. Muscles of intermediate elastin content are the trapezius, rhomboideus and pectoralis superficilias (about 0.4 to 0.8% DFFS). The muscle of the skin, panniculus, has a somewhat higher content of about 1.2% DFFS. Elastin appears to contribute to the toughness of a cooked muscle to about the same extent as denatured collagen. Thus the semitendinosus and biceps femoris have similar total connective tissue contents, and are about equally tough, but the former contains 15 times more elastin than the latter.     

去骨方法对牛肉和火鸡肉化学成分及一些特性的影响

大部分肉经人工预先剔除后的动物骨架或家禽胴体，可以利用机械设备分离回收剩余的残留肉。这种残留肉统称为机械去骨肉（MDM）或机械分割肉。机械去骨是将肉和骨头一起碾碎，再使肉骨混合物通过筛网或隙板分离骨渣，进而回采大部分的残留肉。获取的机械去骨肉最终呈粉碎状。由于好的粘结性和相对低廉的价格，去骨禽肉经常用在粉碎肉产品的配方中。去骨肉最终产品的成分和贮存稳定性受去骨加工时使用的原料和加工条件的影响。机械去骨导致肉细胞分裂，蛋白质变性，并增加脂质和血红素的氧化。     

Comparison of physicochemical properties of beef potentiators prepared by synergistic fermentation and traditional method

Beef potentiator was prepared by beef qu, which was previously prepared by a novel synergistic fermentation method (BPSF). Three kinds of other beef potentiators were prepared by commercial enzymes (protamex, flavourzyme and papain, BPCEs), which were used as controls to investigate the physicochemical properties of BPSF. Results showed that BPSF possessed a higher protein recovery (70.99%) and degree of hydrolysis (DH, 51.39%) than BPCEs. The tests of molecular weight distribution and free amino acids (FAAs) indicated that the moderate molecular weight peptides (1–5 kDa) were dominant (70.07–74.43%) in all beef potentiators. The low molecular weight peptides (<1 kDa), umami amino acids and total amino acids in BPSF, were 1.03‐ to 5.56‐, 5.25‐ to 26.50‐ and 1.57‐ to 4.79‐fold higher than those in BPCEs, respectively. Meanwhile, hierarchical cluster analysis indicated that BPSF was significantly different to BPCEs, and sensory evaluation showed that BPSF had apparently stronger umami taste than BPCEs.     

Thermomechanical properties of beef muscle

Differential scanning calorimetry (DSC) was used to follow the three major endothermic transitions (T(1), T(2) and T(3)) of beef muscle during heating. Borchardt and Daniels reaction kinetics were used to predict the three time and temperature treatments required to sequentially eliminate each transition. Longissimus dorsi and semimembranosus muscles were removed from beef carcasses suspended by Achilles tendon or pelvis. Samples prepared by heating for 5 min at 57°C (I), 70°C (II) and 81°C (III) were assessed by sensory panel for tenderness, juiciness and residual connective tissue. Weight loss, Warner-Bratzler (W-B) shear and microstructure using transmission electron microscopy (TEM) were also determined. The I treatment showed a significant difference in tenderness and residual connective tissue between muscles, but not between contraction states. The II treatment produced collagen shrinkage and a significant drop in W-B shear and residual connective tissue, coupled with increased tenderness in semimembranosus muscle. An increased W-B value, decreased juiciness, increased weight loss and a reduction in sarcomere and A-band length accompanied the III transition. Muscles from carcasses that had been suspended by the pelvis were found to be significantly more tender than the same muscles from Achilles hung carcasses. It is concluded that DSC is capable of determining amount of protein denaturation and, hence, degree of cooking.     

Effect of muscular hypertrophy on physico-chemical, biochemical and texture traits of meat from yearling bulls

The effect of the presence of the double-muscling gene either homozygous (mh/mh) or heterozygous (mh/+) on the physico-chemical, biochemical and texture traits of Longissimus thoracis muscle of yearling bulls of the Asturiana de los Valles (AV) breed was studied. Meat of mh/mh bulls had lower amount of intramuscular fat (p<0.001) and also lower total (p<0.01) and insoluble collagen (p<0.05), although the double-muscling genotype did not affect collagen solubility. Homozygous animals had lower pigment content (p<0.05) and a lighter meat, showing lower water holding capacity, estimated as expressible juice under pressure (p<0.001). Genotype affected significantly the metabolic traits of muscle, with mh/mh animals having higher muscle glycolytic metabolism, assessed by a higher (p<0.001) lactate dehydrogenase (LDH) activity and lower (p<0.001) oxidative activity of the isocitrate dehydrogenase (ICDH). The percentage of myosin heavy chain I in muscle was lower, although not significantly, for mh/mh bulls compared to mh/+ bulls. Texture measurements performed on raw material showed that meat of mh/mh bulls had lower resistance to total and 80% compression, which means lower background or collagen toughness. However, there were no differences between genotypes on shear force of cooked meat. Therefore, the physico-chemical, biochemical and texture traits of meat from mh/mh and mh/+ bull are in general significantly different, which could affect the sensorial quality of meat and hence the consumer acceptance.     

Effects of high-intensity high-frequency ultrasound on ageing rate, ultrastructure and some physico-chemical properties of beef

High-intensity and high-frequency ultrasound was tested for its ability to accelerate meat ageing and increase beef tenderness. Samples (≈50g) of semimembranosus muscles from 8 cull cows were assigned to ultrasonic treatment (2.6MHz; 10W/cm(2); 2 ×15s) either pre-rigor (day 0, pH 6.2) or post-rigor (day 1, pH 5.4). When applied pre-rigor, ultrasound induced a slight delay in rigor mortis onset, a stretching (12-15%) of the sarcomeres (p<0.05), an ultrastructural alteration in the Z-line region and an immediate increase (around 30%) in the release of calcium in the cytosol (p<0.05). However, no conclusive effect on meat ageing rate was observed. Post-rigor ultrasonic treatment did not induce any structural modification but slightly improved the ageing index after 6 days (p<0.05). However, no improvement in the final (day 14) ageing index was observed compared to the controls. As ultrasound had also no effect on the thermal stability of collagen, at both postmortem times, no improvement in meat tenderness can be expected under the conditions used.     

Comparison of some physical and chemical properties of selected game meats

There were no significant differences in proximate composition of the different game meats. Game meats were similar in composition to beef, though beef had lower crude fat contents than expected. Myoglobin content was highest in zebra meat and lowest in oryx meat and there were significant differences (p < 0.01) between zebra and kongoni on one hand and oryx and beef on the other. Leg had higher myoglobin contents than loin. Kongoni, oryx and beef lipids consisted mainly of saturated fatty acids while those in zebra lipids were predominantly unsaturated. Zebra meat was darker than meat from other species due to its high myoglobin content. Oryx meat had the highest lightness (L (?)), and chromaticity (a (?) and b (?)) values. This gave it a bright appearance compared to the other species, though zebra meat had the highest hue angle value and thus redness. However, both oryx and kongoni meats showed a tendency to accumulate metmyoglobin at the surface. Zebra meat had less cooking loss compared to meat from the other species, including beef.     

The effects of different plant oils on some emulsion properties of beef, chicken and turkey meats

The effects of different plant oils (soybean, hazelnut, canola, sunflower, corn, cotton and olive) on emulsion capacity (EC), emulsion stability (ES), emulsion density (ED) and apparent yield stress values of emulsion (raw emulsion; AYSe) and emulsion gel (cooked emulsion; AYSg) of beef, chicken and turkey meats were studied by using a model system. Olive oil increased EC, AYSe and AYSg values and corn oil increased ES values significantly (P < 0.01). Moreover, olive oil decreased ED values significantly (P < 0.01). The effects of chicken meat on EC, turkey meat on ES and beef on AYSe were found to be significant (P < 0.01). The plant oils increased EC values of chicken meat significantly (P < 0.01). Olive oil had higher effect on EC values of chicken, beef and turkey meat. It was found to be 140.7, 132.5 and 128.9 mL (450 mg)⁻¹ protein, respectively. However, olive oil had higher effect on AYSg values of turkey, chicken and beef. It was found to be 492.9, 492.3 and 487.7 Nm⁻², respectively. In addition, olive oil decreased ED values of beef significantly (P < 0.01). The effect of corn oil on ES values of beef was found to be higher (P < 0.05) as 75.77%.     

Osmotic properties of post-rigor beef muscle

The osmotic pressure of beef sternomandibularis and psoas muscles ranged from 480 to 540 mOs, which is almost twice that of pre-rigor muscle (about 300 mOs). The post-rigor osmotic pressure appears to be satisfactorily explained by the low molecular weight components. Muscle samples were soaked at 2°C for 24 h in various solutions and sample weight changes were recorded. Samples soaked in buffered mannitol solutions exhibited weight changes indicative of predictable osmotic behaviour. Those samples soaked in buffered salt solutions (KCl, NaCl), however, exhibited dramatic increases in weight, irrespective of the solute concentration. The reasons for this are not clear. These results indicative that the use of salt solutions, such as 0·15 m KCl, for studies on post-rigor muscle is suspect and conclusions from such studies may be unfounded.     

Comparison of changes occurring in functional properties of nutria meat cured by dry method and beef cured without or with the participation of enzymatic preparation

The influence of the curing time of nutria meat on pH, water holding capacity, emulsion stability (expressed as a quantity of bound oil, ES₀, and water, ES_w), heat contraction and cooking losses was studied. The results were compared to that obtained earlier from beef cured without or with participation of enzymatic preparation. In all experimental periods the values of pH, water holding capacity, ES₀ and ES_w for nutria meat were lower when compared with beef. On the other hand, such values like emulsifying capacity, heat contraction and cooking losses for nutria meat and beef cured with enzymatic preparation were comparable and preferable to corresponding for beef cured without enzymatic preparation. The occurence of extreme majority of functional properties happened between 36 and 106 h of curing the nutria meat and 38 and 96 h or 43 and 108 h of curing beef without or with enzymatic preparation, respectively. Significant correlations were found between water holding capacity and both heat contraction and cooking losses and between heat contraction and cooking losses for nutria meat alike for beef.     

Acceptability and functional properties of restructured roast from frozen pre-rigor injected beef

Restructured beef roasts, made to a standardized formulation, were prepared using the following types of meat that had been stored at - 18 °C for 5 or 10 weeks: grass-fed bull beef pre-rigor injected with a salt/phosphate brine; uninjected grass-fed bull beef; uninjected grain-fed beef; a 50:50 blend of pre-rigor injected grass-fed bull beef and grain-fed beef; and a 50:50 blend of uninjected grass-fed bull beef and grain-fed beef. After frozen storage, pre-rigor injected beef had a higher (p < 0.05) ultimate pH than uninjected beef . Grain-fed beef had the lowest ultimate pH. Roasts made from pre-rigor injected beef were redder (higher Hunter a(?) values) than roasts made with uninjected beef (p < 0.05). Roasts made from grain-fed beef were lighter and looked more cooked (higher L(?) and lower a(?) values respectively) than those made with grass-fed beef. Extending frozen storage to 10 weeks decreased the cook yield (p < 0.05), peak force (p < 0.001) and extensibility (p < 0.05). Consumer panellists preferred (p < 0.05) roasts made from pre-rigor injected beef for tenderness, juiciness and overall acceptability compared with roasts made from uninjected beef.     

Physicochemical and sensory properties of restructured beef steaks containing beef heart surimi

Summary Restructured beef steaks containing beef heart surimi were prepared. Changes in flavour, texture, thiobarbituric acid-reactive substances (TBARS), and compression force of the restructured steaks were evaluated after frozen storage (−29 °C) for 1, 30, and 90 days. Incorporation of propyl gallate-washed beef heart surimi improved the steak flavour score by 7%, texture score by 30%, and cooking yield by 4%, compared to non-surimi control steaks. Addition of water-washed surimi (without propyl gallate) also improved physical properties of restructured steaks, but it induced off-flavour and rancidity development.     

Setting control limits for Escherichia coli counts in samples collected routinely from pig or beef carcasses

Records of Escherichia coli counts in samples routinely collected from carcasses were obtained from one pork and three beef packing plants. The data obtained from each plant were divided into sets from consecutive 6-month periods. For each set of counts, log total counts were calculated for subsets of various sizes. For each set of log total counts, the mean (x), the standard deviation (SD), and an action limit of x + 3 SD were calculated, and the set was tested for a normal distribution. With the data from samples collected at the pork packing plant during 6 years, the proportion of samples with counts of zero in the 12 sets ranged from 15 to 45%. For that plant, appropriate action limits could be derived from log total counts for subsets of nine unit values. With the data from samples collected during 8 years at one beef packing plant, the proportion of samples with counts of zero in the 16 sets ranged from 88 to 99%. For that plant, appropriate action limits could be derived from log total counts for subsets of 15 unit values. With the data from samples collected during 2 or 2.5 years at each of the other beef packing plants, the proportion of samples with counts of zero in all sets was > 99%. For those data, action limits could not be derived from values for subsets of log total counts.     

Comparison of methods for measuring sarcomere length in beef semitendinosus muscle

The objective of the study was to compare the precision of the laser method for measuring sarcomere length with the precision of two oil-immersion microscope methods. Eighteen semitendinosus muscles were assigned to one of three post-mortem treatments to provide a wide range in sarcomere length. Two 5·0cm sections were removed from the centre of each muscle. Each section was subdivided into six equal-size pieces and randomly allotted to each of three participating institutions. Analysis of variance revealed that sarcomere length measurement was not significantly affected by the method of measurement or by the technician. For 99% precision, the laser method required 34 measurements, whereas the two microscope methods required 45 and 66 measurements, respectively.