Influence of outdoor rearing and indoor temperature on growth performance, carcass, adipose tissue and muscle traits in pigs, and on the technological and eating quality of dry-cured hams

The effects of restricted outdoor rearing during winter (W) or summer (S), and the influence of indoor ambient temperature [17 °C (I17) vs. 24 °C (I24), the latter being considered as control] on pig growth performance, carcass, muscular and adipose tissue traits, and technological and eating quality of dry-cured hams were evaluated. I17 pigs exhibited higher, whereas W had similar and S lower growth rates than the controls (P<0.001). Carcass traits were not different between groups, except in lower back fat weights of S and W pigs (P<0.01). Decrease in environmental temperature affected the fatty acid composition of the back fat leading to higher MUFA and lower SFA and PUFA contents (P<0.001) in I17 and W pigs, whereas S pigs exhibited higher PUFA levels (P<0.001) and fat firmness (P<0.01) than the controls. Rearing system did not significantly influence the intramuscular fat content of Semimembranosus (P=0.08), and had no effect on ultimate pH. In the Longissimus lumborum, percentage and relative area of R fibers increased in W pigs (P<0.05), but citrate synthase activity did not differ between groups. I17 and W hams exhibited higher processing yields of dry-cured hams than controls (P<0.05). Sensory analyses showed that pig rearing conditions influenced the product appearance, the I17 and W hams exhibiting lower homogeneity (P<0.01) and intensity (P<0.05) of colour, and higher marbling scores (P<0.01) than I24 hams, but had no influence on texture or flavour.     

The effect of feed withdrawal during lairage on meat quality characteristics in ostriches

Commercially reared ostriches (n = 84) were randomly allocated to one of two groups. The first group (stressed: n = 38) was deprived of food for a period of 2.5 days prior to slaughter, to simulate the stress experienced by slaughter ostriches held in holding pens (lairage) at a commercial ostrich abattoir over a weekend. The second group (control: n = 46) was fed normally until 24 h prior to slaughter. Initial live weight as well as hot and cold drumstick weight were independent (P > 0.05) of treatment. Stressed birds lost on average (±SE) approximately three times more weight than control birds over the experimental period (−3.2 ± 0.6 vs. −1.0 ± 0.5 kg, respectively). Full stomach and alimentary tract weights did not differ between treatments although there was a tendency for that derived from stressed birds to have lower stomach contents. The intra-muscular (Muscularis iliofibularis) pH_f of stressed birds was 0.22 units higher (P < 0.01) than that of contemporaries in the control group 1 h post-slaughter (6.03 ± 0.06 vs. 5.81 ± 0.05, respectively). After 26.5 h in a refrigerated room, this difference still remained at 0.25 units (6.46 ± 0.07 vs. 6.21 ± 0.07, respectively; P < 0.05). Post-slaughter changes in intra-muscular pH followed approximately the same trend in stressed and control birds. Intra-muscular temperature was largely independent of treatment, although there was a suggestion of a slightly higher (P = 0.18) temperature in stressed birds immediately post-slaughter. Cooking loss, drip loss and shearing values were not affected (P > 0.05) by the withholding of food for 2.5 days. It can thus be concluded that withholding feed from ostriches on lairage over a period of 2.5 days does not have any negative influence on the meat yield or physical quality traits thereof.     

Performance and carcass characteristics of bulls as influenced by exogenous hormones

One-hundred and forty-four weanling bulls of Angus (A, n = 48), Simmental x Hereford (SH, n = 8) and Simmental (S, n = 48) breeding were either castrated, left intact, left intact and implanted with Ralgro or left intact and implanted with Synovex S. Cattle were slaughtered after 190, 246 or 315 days of high-energy feeding. The right side of each carcass was electrically stimulated. Steers were inferior to intact treatments for most performance and carcass cutability traits, but steers were superior in marbling and lean quality (P < 0·05). There were no differences (P>0·05) in dressing percentage or ribeye area per 100 kg of carcass weight among treatments. Relative to intact bulls, Ralgro and Synovex S increased carcass masculinity. Implanted intact treatments did not differ from nonimplanted intacts for feed conversion, average daily gain, yield grade characteristics, percent longissimus dorsi chemical fat and 9–10dash11th rib composition (P >0·05).     

A method for simultaneous fluorometry and rheology of connective tissue in bulk meat

A probe tipped with optical fibres was mounted on the load cell of a compression tester and pushed into well-aged beef rib roasts (Canada Grade AAA, n = 6, 33 ± 3.6 days post-mortem). Fluorescence (F; excitation 365 nm, emission >420 nm) and reflectance (R; 365 nm) were measured through single optical fibres. Diffuse R was measured using different fibres for illumination and detection, thus responding to tissue between the two fibres. Replication was by a matrix pattern of penetrations on single roasts. For example, in a typical roast, F was correlated with the force of penetration (mean r = 0.86 ± 0.06, n = 20, all P < 0.001). R was less (P < 0.001) strongly correlated with penetration force (mean r = 0.46 ± 0.10, n = 20, all P < 0.001). F signals from connective tissue contained less peaks than R signals from both connective and adipose tissue (respectively, 2.75 ± 0.43 versus 5.57 ± 0.67 peaks cm⁻¹, P < 0.001, n = 20 pairs) and F peaks were wider than R peaks (respectively, 3.54 ± 0.88 versus 1.38 ± 0.19 mm, P < 0.001, n = 20 pairs). For the spinales dorsi aponeurosis, the depth at which peak force was reached was strongly correlated with the depths at which both peak F and peak R were reached (r = 0.98, P < 0.001, n = 20 for both). Diffuse R was only weakly correlated with penetration force (mean r = 0.29 ± 0.12 with only 5/10 correlations significant P < 0.001). This new method showed the primary resistance to dorso-ventral penetrometry of well-aged beef rib roasts originated from connective tissue.     

Positional distribution of fatty acids in triacylglycerols from subcutaneous adipose tissue of pigs fed diets enriched with conjugated linoleic acid, corn oil, or beef tallow

This study was conducted to determine the effects of dietary beef tallow, corn oil, and conjugated linoleic acid (CLA) on the distribution of fatty acids among positions within triacylglycerols. Crossbred barrows (n=6 per treatment group) received diets containing 1.5% beef tallow, 1.5% corn oil, or 1.5% CLA for 5 weeks. Subcutaneous adipose tissue samples were obtained immediately postmortem. The fatty acid composition was determined for the sn-2 positions of the triacylglycerols by digestion with Rhizopus arrhizus lipase. Fatty acids in the sn-1/3 position were calculated from these data. Feeding CLA increased (P<0.05) the concentration of total saturated fatty acids (SFA, especially 16:0) and isomers of CLA in adipose tissue lipids, but reduced (P<0.05) the concentration of total monounsaturated fatty acids (MUFA, especially 18:1n−9). Dietary CLA caused an accumulation of total SFA in the sn-1/3 position, with a proportional decrease in total MUFA and 18:2n−6 in the outer positions. Correspondingly, lipids extracted from CLA-fed pigs had slip points that were 10 °C higher (P<0.05) than those from corn oil- or tallow-fed pigs. These data suggest that dietary CLA increases the melting point of lipids in porcine adipose tissue by increasing the proportion of SFA at the sn-1/3 position of lipids.     

Effect of Duroc content, sex and ageing period on meat and eating quality attributes of pork loin

This study was conducted to determine the effect of percentage Duroc content of entire male and female pigs and ageing period on meat and eating quality attributes of pork loin (M. longissimus thoracis et lumborum). A total of 84 pigs [entire males (n=42) and female (n=42)] of 0% Duroc (100% Large White), 50% Duroc (Duroc×Large White) or 100% Duroc (n=14 pigs per sex×genotype combination) were slaughtered at a liveweight of 100 kg. Steaks from the M. longissimus lumborum of female pigs were aged for either 2 or 7 days post-slaughter and evaluated using a consumer taste panel. Eating quality attributes of tenderness, flavour and overall liking of pork loin steaks from female pigs were not (P>0.05) influenced by Duroc content. Pork from 100% Duroc pigs was juicier (P=0.05) and had a higher (1.84%, P=0.05) intramuscular fat content than pork from 0 and 50% Duroc pigs (1.40 and 1.25%, respectively). Pork from entire male pigs had a lower (P<0.001) intramuscular fat content, was darker (P<0.01) in colour and recorded higher (P<0.01) Warner Bratzler shear force values compared with pork from female carcasses. Ageing pork loin steaks in vacuum bags for 7 days improved tenderness (P<0.01), flavour (P<0.05) and overall liking (P<0.05) compared with steaks aged for 2 days post-slaughter. Ageing of pork steaks for 7 days post-slaughter improved eating quality attributes far more effectively than increasing percentage Duroc content of pigs, which only influenced consumer scores for juiciness.     

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.     

AMP-activated protein kinase is negatively associated with intramuscular fat content in longissimus dorsi muscle of beef cattle

Marbling, or intramuscular fat, is an important factor in meat quality. As a key regulator of lipid metabolism, AMP activated protein kinase (AMPK) may be associated with intramuscular fat accumulation. Our objective was to evaluate the relationship among AMPK and its associated signaling mediators, with marbling and lean growth in beef cattle. Steers with high intramuscular fat content (High IMF, 5.71 ± 0.36%, n = 5) and low intramuscular fat content (Low IMF, 2.09 ± 0.19%, n = 5) were selected. High IMF was associated with increased tenderness (P < 0.05) and backfat thickness (P < 0.01). Muscle weights were higher in Low compared to High IMF (P < 0.05). High IMF steers had a reduced AMPK activity (P < 0.01), reduced acetyl-CoA carboxylase phosphorylation (P < 0.05), and reduced total mTOR (P = 0.02) content. Data provide evidence that AMPK is involved in IMF deposition in beef cattle.     

Assessment of breed type and ageing time effects on beef meat quality using two different texture devices

Forty-two male yearlings were used to assess the influence of breed type and ageing time on beef texture. Samples of the M. longissimus dorsi of four breed types [double muscled (DM), dual purpose (Brown Swiss, BS), fast growth (FG) and unimproved type (UT)] were aged for 1, 3, 7, 10, 14 or 21 days at 4°C and frozen at −18°C until analysed. Cooked samples (to end-point of 70°C) were assessed using a Warner–Bratzler (WB) device. Raw samples were assessed using a compression device in which transverse elongation was prevented. There were no significant differences in WB values of cooked meat due to breed type, but ageing had a significant (P<0.05) on maximum load. Ageing, but not breed type, had a significant effect on the compression values of raw meat at low compression rates (P<0.001). Compression values, of raw samples, at 80% compression differed significantly (P<0.001) between breed types, but were not affected by ageing. Compression values of raw samples, at 80% compression, were affected by breed type, probably because of genotype differences in the contribution of connective tissue.     

Ellipsometry across isolated muscle fibres indicates a refractive contribution to paleness in pork

Muscle fibres isolated from pork were mounted in a microscope chamber and pH was controlled with 0.2 M phosphate buffer. Optical path differences between ordinary and extraordinary rays were measured by ellipsometry while a scanning stage moved the fibre across the optical axis of the microscope. The depth of fibre in the optical axis was estimated from the lateral diameter of fibres. Path differences increased as fibre depth increased. Static ellipsometry of unmounted fibre fragments showed maximum path differences at pH 5.5 were higher than at pH 7.0, but variance was high and the difference was not significant (64.4±15.1 nm at pH 5.5 versus 58.9±15.2 nm at pH 7.0, P>0.05, n=40). However, the mean depth of fibre fragments at pH 5.5 was less than at pH 7.0 (53.9±15.1 μm at pH 5.5 versus 70.6±16.1 μm at pH 7.0, P<0.005, n=40). Thus, path differences per micrometre of fibre depth were greater at pH 5.5 than at pH 7.0 (1.25±0.37 nm^{−1 μm} at pH 5.5 versus 0.87±0.31 nm^{−1 μm} at pH 7.0, P<0.0005, n=40). As pH decreases, therefore, muscle fibre diameter decreases while birefringence increases. Refraction through muscle fibres may contribute to pork paleness.     

The influence of season on quality characteristics of hot-boned beef m. longissimus thoracis

Samples of m. longissimus thoracis (LT) muscle were randomly collected from 70 Omani beef cattle 1 h after slaughter between August 2001 and July 2002 in the Muscat Municipality central slaughterhouse to investigate the effect of seasonal parameters on meat quality during the hot and cool seasons of Oman. The collection period (12 months) was divided into two seasons according to ambient temperatures and relative humidity and termed: Cool Season (November–March with average temperature of 21.2±1.40 °C and 57.9±1.61% relative humidity) and Hot Season (April–October with average temperature of 34.3±1.67 °C and 48.8±7.57% relative humidity). The season had a significant effect on meat quality characteristics of the LT muscle. Muscles collected during the hot season had significantly (P<0.001) higher ultimate pH values (6.24) with significantly (P<0.001) lower Warner–Bratzler (WB) shear force values (10.12) than those collected during the cool season (5.54 and 15.58). In these hot-boned samples, there was a linear relationship between ultimate pH and WB shear values. Cooking loss was significantly (P<0.001) higher for cool season samples (26.01%) than from hot season samples (19.75%). Beef from the hot season group had significantly (P<0.001) darker meat than that of the cold season group, based on L* (31.45 vs 35.58), a* (18.53 vs 23.19) and b* (4.16 vs 6.40) colour measurements. There was a linear relationship between ultimate pH and cooking loss, L*, a* and b*. These results indicated that heat stress (>30 °C) lead to physiological stress in beef cattle, which in turn increased muscle ultimate pH and influenced related meat quality characteristics.     

Temperature shows greater impact on bovine Longissimus dorsi muscle glycogen debranching enzyme activity than does salt concentration

The degradation of glycogen progresses by the co-operation of two enzymes: glycogen phosphorylase (phosphorylase) and glycogen debranching enzyme (GDE). We studied the effect of temperature (4–42 °C) and salt concentration (0–3% NaCl) on bovine M. longissimus dorsi GDE activity. GDE activity (n = 4) decreased significantly with decreasing temperature from about 40–4 °C. GDE exhibited 52% activity at 25 °C and 11% at 4 °C compared to its optimum activity measured at 39 °C. In rapidly chilled meat, the reduction in GDE activity may substantially delay the rate of glycolysis. However, residual GDE activity at 4 °C seems sufficient to enable the attainment of normal ultimate pH if the available time is long enough. An increase in salt concentration from 0% to 2% and to 3% induced a significant (P < 0.001) increase in the ultimate pH of ground bovine meat (n = 6), but showed no effect on GDE activity.     

Quality properties of pork sausage prepared with water-soluble chitosan oligomer

Emulsion type sausage was prepared with the addition of a chitosan oligomer (molecular weight 5000, 0.2%) and compared to a control. Sausages were aerobic- or vacuum-packaged and stored in a 4°C refrigerator for 3 weeks. Difference of microbial growth between the sample with added chitosan oligomer or control was not observed (P>0.05). Lipid oxidation was lower in the sausage with chitosan oligomer at 3 weeks in aerobic packaging (P<0.05) than in the control sausage. The surface color of the sausage with chitosan oligomer had higher Hunter color L*- and b*-value. Hunter color a*-values were lower in the chitosan oligomer-added sausage and the a*-value increased during storage regardless of packaging (P<0.05). Sensory panels did not detect any difference in color, flavor, texture, and overall acceptance, and mechanical texture analysis also showed no difference. Therefore, the quality of the sausage with added chitosan oligomer (0.2%) was acceptable.     

Influences of the method of housing bulls on their body composition and muscle fibre types

The influence of the type of housing (loose or tying-type) was studied in relation to body composition and muscular characteristics of bulls. 34 young bulls (18 Salers and 16 Limousins) were divided into two groups with equal breed representation and equal mean growth rates, to 10 months of age. One group was housed in tying-type housing (short stalls 1·8 m² per animal) and the other in loose housing (6·5 m² per animal). Samples of semitendinosus (ST) and longissimus thoracis (LT) muscle were taken at slaughter at 16 months. The lactate dehydrogenase (LDH) and isocitrate dehydrogenase (ICDH) activities were measured. The proportion of isoforms LDH-M and LDH-H were determined for each muscle. Total collagen content and solubility were measured for ST alone. Fibres were classified by ATPase myofibrillar and succinate dehydrogenase activities into SO (slow oxidative), FOG (fast oxidative glycolytic) or FG (fast glycolytic), and by immunohistochemistry by reaction with monoclonal antibodies specific to slow and fast myosin heavy chain reactions into I, IIC, IIA, IIAB and IIB fibres. Compared with animals in tying-type housing, animals in loose housing presented the following: fewer carcass adipose deposits (p<0·01); for ST muscle, more collagen (p<0·01) and a reduced glycolytic metabolism, as indicated by lower LDH activity (p<0·10) and a lower proportion of FG fibres (p<0·10). In both ST and LT muscles, loose housing resulted in an increased percentage of IIC fibres (p<0·05) but did not alter the proportions of fast fibres. Modifications in ST alone were increased percentage of IIA fibres (p<0·10) and IIAB fibres (p<0·01) and a lower percentage of IIB fibres (p<0·01). Thus, for a given rate of growth, the type of housing (loose or tying-type) influenced contractile characteristics, especially in muscles involved in movement.     

A comparison of halothane homozygous negative and positive pietrain sire lines in relation to carcass and meat quality, and welfare traits

Barrows (n=164) and gilts (n=249) from crosses of a Pietrain homozygous halothane recessive (Pi nn) and two Pietrain homozygous dominant (Pi NN-a and Pi NN-b) sire lines with Landrace×Large White NN sows, were used to study the effect of terminal sire and pre-slaughter treatment on meat quality and animal welfare. The pigs from each of the two farms where they were finished were delivered to the abattoir in two batches differing in the pre-slaughter conditions. A total of 90 pigs (54 NN and 36 Nn) were assigned to a long pre-slaughter treatment (6 h transport and 14.5 h lairage) and 89 (57 NN and 33 Nn) to a short pre-slaughter treatment (4.5 h transport and 2.5 h lairage) in Farm 1, and 118 (65 NN and 53 Nn) to the long (7 h transport and 14 h lairage) and 114 (66 NN and 48 Nn) to the short pre-slaughter treatment (1.5 h transport and 2 h lairage) in Farm 2. In Farm 1, heart rate of 3 NN and 3 Nn gilts was recorded throughout loading and transport and blood samples from 5 NN and 5 Nn were collected before loading and after transport to measure cortisol, creatine phosphokinase (CPK) and lactate dehydrogenase (LDH). Carcasses were classified and commercial cutting was carried out. At 24 h, meat quality was assessed on the Longissimus thoracis muscle by measuring electrical conductivity (PQM), colour (Minolta CR 200 and Japanese scale), pHu and drip losses. Halothane carriers showed a higher mean heart rate and higher increase in CPK levels (P<0.05) after transport in the short pre-slaughter treatment than halothane free pigs. No effect was observed in cortisol or LDH values. Pi NN-a sired pigs had a higher live and carcass weight (P<0.001) and loin depth (P<0.05), but lower killing out percentage (P<0.01) and leg yield (P<0.01) compared with the progeny of the other two terminal sires. Gilts were leaner (P<0.001), had a higher killing out percentage (P<0.001) and higher yields of primal cuts (P<0.001) compared with barrows. Pi nn sired pigs had poorer meat quality (higher PQM values in both farms, P<0.01) than Pi NN-a sired pigs. Long pre-slaughter treatment resulted in darker meat (P<0.01) in both farms and in higher pHu (P<0.001) in Farm 1 than short pre-slaughter treatment. Conversely, pigs subjected to the short pre-slaughter treatment showed higher PQM values (P<0.01) in Farm 1 and higher PSE percentage (P<0.05) in both farms compared to the ones subjected to the long pre-slaughter treatment. These results suggest that Pietrain halothane free sire lines could produce similar results on carcass quality to halothane carriers, without compromising meat quality and welfare.     

Carcass yield, composition and meat quality attributes of sheep and goat under semiarid conditions

Carcass composition and meat quality attributes were compared in yearling sheep and goats. After weaning at 3 months of age, the animals were maintained under stall fed condition up to 1 year of age. Throughout the study, the animals were maintained on ad libitum complete feed (50:50 roughage and concentrate). The yearling sheep had higher (P<0.05) pre slaughter weight, hot carcass weight and dressing % than the goats. The muscular development as indicated by loin eye area was significantly (P<0.01) greater in sheep than goats. In general, total non-carcass fat contents were more in sheep than goats. Similarly, the dissected total fat of half carcass was also more (P<0.01) in sheep than the goats. Neck and shoulder portion was heavier (P<0.01) in goats than the sheep. Shear force value was greater (P<0.01) in goats (7.42 kg/cm²) than sheep (3. 74 kg/cm²). Goat meat had more (P<0.01) moisture and less fat than mutton. In sensory evaluation both the species were rated almost equal in overall palatability scores. The current study showed that dressing yield was higher in sheep than goats. But goat yielded leaner carcass which is desirable for the calorie concern consumers. It was also revealed that meat from goat carcasses was tougher than mutton.     

The effect of production system and age on concentrations of fatty acids in intramuscular fat of the longissimus and triceps brachii muscles of Angus-cross heifers

The concentrations of fatty acids were measured in intramuscular fat from the longissimus lumborum (LL) and triceps brachii (TB) muscles of Angus-cross heifers finished either on a high-concentrate ration in Washington, USA, (US cattle, n = 15) or on pasture in New Zealand (NZ cattle, n = 16). Half of the NZ cattle were of a similar age to the US cattle (NZAge) and half were of a similar weight (NZWt). Intramuscular fat levels were higher for the LL muscle and for the US cattle but only within the LL muscle (P < 0.05). Aspects of the fatty-acid patterns that are of relevance to human nutrition tended to favour the pasture-finished NZ cattle with lower n − 6/n − 3 fatty acid ratios (P < 0.001), higher concentrations of an anticarcinogenic conjugated linoleic acid (C18:2 c9,t11) (P < 0.05) and its precursor (trans-vaccenic acid, TVA) (P < 0.01), and lower levels of the 18-carbon trans monounsaturated fatty acids other than TVA (P < 0.01). Concentrations of 20 of the 22 fatty acids analysed differed significantly between the two muscles. When values were adjusted to a common intramuscular fat level by covariance, most of the group differences remained, but a number of the muscle differences became non-significant. For almost half the fatty acids considered, there was a significant interaction between treatment group and muscle, which indicates that the results for one muscle do not necessarily apply to other muscles, although the ranking of the groups was usually the same for both muscles.     

Effect of season on color of Hanwoo (Korean native cattle) beef

A total of 1278 head of Hanwoo (Korean native cattle) slaughtered over four seasons were used to evaluate the effect of season on color characteristics of beef longissimus dorsi (LD) muscle. CIE L^*, a^*, b^*, C^* values and hue angle were significantly lower (P<0.05) in cattle slaughtered in the winter season. Meat color was darker in the winter than in the spring and autumn seasons. The L^* values among three average daily temperature (T_a) categories were different (P<0.05) in order of: [5 °CT_a<25 °C] > [T_a25 °C] > [T_a<5 °C], indicating that the meat color of cattle slaughtered at T_a<5 °C was darker. The a^*, b^*, C^* values and hue angle were significantly lower (P<0.05) in cattle slaughtered at T_a<5 °C. Season at slaughter is of great importance for meat color. Namely, meat color of Hanwoo beef was influenced by environmental temperature. Overall, cattle slaughtered in the winter season of T_a<5 °C produced beef with more undesirable meat color properties.     

Tenderness and collagen composition of beef semitendinosus roasts cooked by conventional convective cooking and modeled, multi-stage, convective cooking

Beef semitendinosus roasts were cooked in a forced-air convection oven using conventional or modeled, multi-stage cooking. Conventional cooking was defined as cooking at 163°C to a core endpoint of 65°C. The model method was developed using a finite difference heat and mass transfer model optimized for a three-stage cooking process that included preheating, holding, and finishing. Model cooking resulted in lower (P<0.05) Warner–Bratlzer peak shear force values than conventional cooking (3.3 vs 4.7 kg). Collagen total unaltered fraction was lower (44 vs 55%, P=0.05) and enzyme labile fraction was higher (56 vs 45%, P<0.05) in the model-cooked samples than in conventionally cooked samples. The three-stage cooking process results in a more tender product without adversely affecting product yield.