Meat quality characteristics of springbok (Antidorcas marsupialis). 1: Physical meat attributes as influenced by age, gender and production region

Springbok is the most extensively cropped game species in South Africa. The effects of age (adult, sub-adult, lamb), gender and production region on the physical attributes (pH₂₄, cooking and drip loss, Warner Bratzler shear force and colour) were determined using samples of the M. longissimus dorsi (LD) muscles of 166 springbok. Stressed animals had a higher (P < 0.05) pH₂₄ (6.3 ± 0.07), as observed in the meat originating from the Caledon region. This meat had lower (P < 0.05) cooking loss (27.2 ± 0.62%) and drip loss (1.8 ± 0.08%) values in comparison to meat originating from the other regions. Inverse correlations were noted between pH₂₄ and drip loss (r = −0.26, P < 0.01) and cooking loss (r = −0.42, P < 0.001). Shear force values (kg/1.27 cm diameter) correlated positively (r = 0.25, P < 0.01) with pH₂₄. Age-related effects on tenderness were small in comparison with pH₂₄ effects. CIELab colorimetric values were typical of game meat and venison (L^* < 40, high a^* and low b^* values). It was noted that pH₂₄ correlated negatively (r = −0.51, P < 0.001) and positively (r = 0.33, P < 0.001) with the hue-angle and the chroma value of colour, respectively. Springbok originating from Caledon had a significantly (P < 0.05) higher a^* value, indicating meat to be more red with higher colour saturation.     

Physicochemical and sensory properties of chicken nuggets with washed mechanically deboned chicken meat: Research note

The effects of different proportions (0%, 10%, 20%, 30%, 40%) of washed mechanically deboned chicken meat (WM) as a substitute for hand deboned chicken meat, on the physicochemical and sensory characteristics of chicken nuggets were evaluated. The addition of WM increased fat content, but it was only significant (P < 0.05) when 40% of WM was added, whereas the protein content was significantly (P < 0.05) reduced as from 20%. Significant differences (P < 0.05) were found in L^*, a^* and b^* values with different proportions of WM, however, these differences were evidently not discerned as shown by the no significant differences (P > 0.05) in ΔE^* color scores. The addition of WM did not affect (P > 0.05) sensory attributes of chicken nuggets. From a technical viewpoint, up to 40% WM could be incorporated into nugget formulation instead of hand deboned chicken meat without affecting sensory attributes of the product. Minor changes in composition were observed but they were probably not detrimental to the product.     

Effects of transportation at high ambient temperatures on physiological responses, carcass and meat quality characteristics of three breeds of Omani goats

The experiment was designed to determine the effects of short road transportation in an open truck during the hot season on live weight shrink, physiological responses, carcass, and meat quality characteristics in three breeds of Omani goats. Forty-two male goats (12 months of age) representing equally three breeds of Omani goats (Batina, Dhofari, and Jabal Akhdar) were divided into two groups: 2 h transportation stress (TS) or not transported (NT). The NT group remained unstressed in holding pens with feed and water provided ad libitum prior to slaughter, while the TS group was transported on the day of slaughter 100 km in an open truck. The average temperature during transportation was 37 °C. All animals were blood-sampled before loading and prior to slaughter via jugular venipuncture. Animals were weighed just before loading onto a truck and after transport to assess shrinkage. Muscle shear force, sarcomere length, pH, expressed juice, color, and cooking loss were measured on samples from Mm longissimus dorsi (LD), biceps femoris (BF), and semitendinosus (ST) muscles collected at 24 h postmortem at 1–3 °C. Live weight shrinkage losses were between 1.07 and 1.28 kg. The TS goats had higher plasma cortisol (P < 0.01), adrenaline, nor-adrenaline, and dopamine concentrations (P < 0.05) than NS goats. Blood serum from Batina goats had significantly (P < 0.05) higher cortisol, adrenaline and dopamine and nor-adrenaline concentrations than those from Jabal Akdhar goats. Transportation stress had a significant (P < 0.05) effect on meat quality characteristics of the LD, BF, and ST muscles. Meat from TS goats had significantly higher ultimate pH, expressed juice, cooking loss percentage, shear force, but significantly lower sarcomere length, L^*, a^*, and b^* values. LD muscles of Batina goats had significantly higher ultimate pH values and lower L^* values than Dhofari and Jabal Akdhar goats. These results indicated that subjecting goats to the 2-hour road transportation with high ambient temperatures can generate major physiological and muscle metabolism responses.     

Chemical, instrumental and sensory characteristics of cooked pork ham

Instrumental, chemical and sensory parameters of cooked pork ham were evaluated. Principal component analysis was carried out on the basis of the instrumental variables related to colour and texture. The four PCs account for almost 94% of the total variance in the data set. The PCA only separated 3 hams with a^* > 10. Hardness was correlated with non-collagen muscle protein (P  0.01), gumminess (P  0.01) and ash (P  0.05). Sensory evaluated tenderness showed positive significant correlation with L^* (P  0.01). The most important colour parameter seems to be a^*, which was negatively correlated with sensory evaluated parameter colour (P  0.01). The PCA performed on all parameters (sensory, chemical and textural) discriminated two groups of hams differing in non-collagen muscle protein content and hardness.     

Effects of rigor temperature and electrical stimulation on venison quality

The effects of rigor temperature and electrical stimulation on venison quality were assessed using venison longissimus dorsi muscle. In the first trial, effect of rigor temperature (0, 15, 25, 30, 35 and 42 °C) and time post-mortem (at rigor, 3, 7 and 14 days) on drip and cooking losses, % expressible water (water holding capacity, WHC), sarcomere length, protein solubility, meat tenderness and colour were investigated. In the second trial, the effects of rigor temperature (15 and 35 °C), electric stimulation (stimulated or not stimulated) and time (at rigor, 3 and 6 weeks post-mortem) on tenderness and colour were further investigated. Results of the first trial showed no clearly established trends of the effect of rigor temperature and time on the cooking and drip losses and protein solubility except venison muscles that went into rigor at 42 °C tended to have higher drip loss and lower protein solubilities compared to muscles that went into rigor at the other temperatures. Venison water holding capacity (WHC) decreased with the increase in rigor temperature (P < 0.001) and venison became more tender with time post-mortem. Venison colour improved with increasing rigor temperature. During display, samples that went into rigor at 15, 25 and 35 °C had the lowest and those at 0 and 42 °C had the highest rate of change of redness (a^*) value with time. In the second trial, tenderness was improved by stimulation (P = 0.01). Redness (a^*) values were affected by rigor temperature (P < 0.01) and post-mortem time (P < 0.001) but not by electrical stimulation. It is concluded that venison tenderness can be improved via the manipulation of rigor temperature to obtain acceptable level of tenderness early post-mortem with less damaging effect on colour stability.     

Meat quality in suckling lambs: effect of pre-slaughter handling

Thirty-three suckling lambs of the Manchega breed were used to compare the effects of pre-slaughter handling (PSH) on initial meat quality and at 7 days post-mortem. Lambs were distributed into three groups: electrically stunned (ESL; n=15), stunned using CO(2) (GSL; n=10) and slaughtered without previous stunning (USL; n=8). Meat quality was evaluated by examining pH, colour (L*, a*, b* values), water holding capacity (WHC), cooking loss (CL), shear force (SF) and drip loss (DL). At 24 h post-mortem, the highest pH corresponded to the USL group (P<0.05) whereas the lowest pH decline (pH(0)-pH(24)) corresponded to the GSL group (P<0.05). Differences in pH among groups disappeared after 7 days post-mortem. In general, PSH did not affect values of WHC, CL and colour parameters. After 7 days post-mortem, there were significant differences between groups in DL, this being lowest (P<0.05) in stunned animals. GSL resulted in more tender meat (lower SF value) than ESL and USL (P<0.05). Moreover, there was no blood splash in any of the carcasses of the GSL group.     

Influence of dietary inclusion level of manganese on pork quality during retail display

Boneless pork loins (n = 112) were used to test the influence of dietary manganese (Mn) inclusion level on pork quality traits during retail display. Crossbred barrows and gilts were fed diets formulated with 0, 20, 40, 80, 160, or 320 ppm Mn from Availa^®Mn (AvMn; a Mn–amino acid complex) from 23.8 to 106.8 kg live weight. At approximately 48 h postmortem, boneless pork loins were fabricated into longissimus thoracis et lumborum (LM) chops, which were subsequently placed in open-topped, coffin-chest display cases (2.6 °C) under continuous warm-white, fluorescent lighting (1600 lx) for 7 days. Dietary Mn level had no effect on LM pH (P = 0.47), purge volume (P = 0.60) and loss (P = 0.53), or moisture loss (P = 0.95) during retail display. Chops from pigs fed 80 ppm Mn received higher (P < 0.05) American and Japanese color scores than pigs fed 0 and 40 ppm Mn. Even though the LM from pigs fed 80, 160, and 320 ppm Mn tended to be darker (lower L^* values; P = 0.07) than chops from pigs fed 40 ppm Mn, a^* (redness) and b^* (yellowness) values, as well as hue angle and chroma, were not (P  0.19) affected by dietary Mn. On days 0 and 1, the reflectance ratio of 630 nm/580 nm was similar (P > 0.05) among dietary Mn supplementation levels; yet, by day 4 of retail display, chops from pigs fed 80 ppm Mn had higher (P < 0.05) reflectance ratios than chops from pigs fed 0, 20, 40, and 160 ppm, whereas LM chops from pigs fed 40 ppm Mn had lower (P < 0.05) reflectance ratios than all other dietary treatments on day 7 (Mn supplementation level × display day; P = 0.04). Although TBARS were greater (P < 0.001) on day 7 than 0 of retail display, TBARS values did not (P = 0.43) differ among dietary Mn levels. Results indicate that supplementing swine diets with 80 ppm Mn may improve pork color during retail display without increasing the likelihood of lipid oxidation.     

The influence of early post-mortem enhancement and accelerated chilling on pork quality

To improve pork quality, the effectiveness of early post-mortem enhancement and accelerated chilling were investigated. The four treatments evaluated were: Enhancement with Accelerated Chilling (ENAC), Accelerated Chilling Only (ACO), Enhancement with Conventional Chilling (ENCC), and Conventional Chilling Only (CCO). ENAC had a higher (P < 0.05) pH than all other treatments. CCO resulted in the highest (lightest; P < 0.05) L^*, while ENAC had the lowest L^* value (darkest; P < 0.05). Subjective color and striping did not differ (P > 0.05) between ENAC and ENCC, although ENAC was numerically higher for both parameters. Sensory analysis for juiciness and tenderness were not different (P > 0.05) between ENAC and ENCC, but both were higher (P < 0.05) than ACO and CCO. Enhancement early post-mortem coupled with accelerated chilling may be used to improve instrumental color and pH over conventional processing methods.     

Stunning and shackling influences on quality of porcine Longissimus dorsi and Semimembranosus muscles

Seventy-one barrows of three porcine genotypes (nn, Nn and NN genotypes with respect to halothane) were electrically stunned on the right side and randomly assigned to one of three treatments during the bleeding process (prone, PR; shackled left, SL; or shackled right, SR) to investigate the influence of both shackling and stunning on ultimate meat quality. PR carcasses had less side-to-side variation in 40 min pH than either SL or SR carcasses. Shackling contributed to a decreased 40 min pH in the semimembranosus (SM) and posterior longissimus dorsi (PL). The effects of stunning appeared to be additive when combined with shackling, tending to lower pH in the mid-longissimus dorsi (ML; P <- 0·10). The ‘free’ side of the shackled carcass also had significantly lower 40 min pH in the ML, PL and SM locations when compared to PR sides. Genotype had no influence on shackling since there was no treatment by genotype interactions. Despite significant effects on post-mortem metabolism (indicated by the differences in 40 min pH) shackling alone had little influence on overall ultimate meat quality of the carcass. Depending on the sampling location, soluble protein and L^* and b^* values varied among treatments. Shear force and a^* values were similar among treatments, but PR and SL carcasses had significantly lower expressible juice and drip loss compared to SR carcasses. These results suggest that, although shackling alone has little effect on meat quality, in combination with electrical stunning, shackling can lead to a decrease in meat quality.     

Comparisons of longissimus muscle metabolic enzymes and muscle fiber types in Korean and western pig breeds

We compared differentially expressed genes and muscle fiber types in the longissimus muscles of Korean native pigs (KNP) and the western meat-producing breeds Landrace and Yorkshire. The KNP breed exhibited a higher muscle fat content and more red meat color as determined by the a^* (redness) value (P < 0.01) and b^* (yellowness) value (P < 0.05) compared to the western breeds. Using differential display RT-PCR, we detected two genes that were differentially expressed in skeletal muscle among the pig breeds. These genes were identified as NADH dehydrogenase subunit 1 and ATPase subunit 6 by cloning and sequencing analysis. Both of these genes are involved oxidative phosphorylation and therefore energy metabolism. The genes were more highly expressed in the KNP breed than in the other breeds, indicating that KNPs exhibit more oxidative metabolism than do the western breeds. We also analyzed the mRNA levels of myosin heavy-chain isoforms such as type I (oxidative), type IIb (glycolytic), and types IIa and IIx (intermediate) fibers using real-time RT-PCR. The mRNA levels of oxidative and intermediate fibers were elevated in the KNP breed, whereas the glycolytic fibers were more highly expressed in the Landrace and Yorkshire pigs. These results suggest that the elevated expression of the oxidation-related metabolism genes NADH dehydrogenase and ATPase is related to meat quality as indicated by a higher content of oxidative fibers and muscle fat, as well as redder meat color.     

Effects of age on composition and quality of muscle Longissimus thoracis of the Omani Arabian camel (Camelus dromedaries)

The aim of this study was to determine the effects of age on chemical composition and quality characteristics of the Arabian one-humped camel’s meat. Samples of longissimus thoracis (between the 10th and the 13th rib of the left side) were randomly collected from 21 Omani intact male camels of three different age groups: group 1 (1–3 years), group 2 (3–5 years) and group 3 (6–8 years). Samples were chilled (1–3 °C) for 48 h. Moisture, crude protein, fat and ash were determined on freeze dried ground muscle. Mineral contents were determined using an Inductively coupled plasma emission spectrometer (ICP). Meat quality including ultimate muscle pH, Warner–Bratzler shear force, sarcomere length, myofibrillar fragmentation index, expressed juice, cooking loss percent, and colour L^*, a^*, b^* were measured using standard methods.

The moisture, protein, fat and ash ranged from 64.4% to 76.7%; 18.6% to 25.0%, 1.1% to 10.5% and 1.0% to 1.4% on dry matter basis, respectively. The Ca, Mg, Na, K, P, Cad, Cr, Ni, Pb, Co, Mo, Be and V ranged from, 9.2 to 46.6, 24.7 to 57.3, 104.7 to 257.0, 471.4 to 1053.0, 249.9 to 584.0, 0.005 to 0.024, 0.020 to 0.410, 0.016 to 0.187, 0.010 to 0.299, 0.010 to 0.018, 0.050 to 0.470, 0.005 to 0.030 and 0.013 to 0.141 mg/100 g on dry matter basis, respectively. The percentage of protein decreased and that of fat increased with increasing camel age. The ultimate pH, shear force, sarcomere length, fragmentation index, expressed juice, cooking loss, lightness (L^*), redness (a^*) and yellowness (b^*) ranged from 5.46 to 6.64, 4.25 to 17.82, 0.96 to 2.50, 55.91 to 94.81,19.50 to 33.63, 13.18 to 29.88, 27.86 to 43.21, 10.46 to 22.81, and 4.63 to 10.11, respectively. Muscles of younger camels (group 1) had significantly (P < 0.05) lower shear force value, ultimate pH and higher sarcomere length, fragmentation index, expressed juice, cooking loss, and lightness color (L^*) by 48%, 3.4%, 43%, 25%, 28%, 14%, and 16% than those collected from older camels (group 3), respectively. Values of middle age camels (group 2) camels were in-between. This study confirmed that camel meat is healthy and nutritious as it contains low fat as well as being a good source of minerals. Age is an important factor in determining meat quality and composition.     

The effects of electrical stunning and percussive captive bolt stunning on meat quality of cattle processed by Turkish slaughter procedures

The effects of electrical and percussive captive bolt stunning both on initial and up to 14 days post mortem meat quality of Friesian young bulls were studied. The first group (NS; n=10) were slaughtered without stunning under Turkish slaughter procedure (these animals were slaughtered under conditions acceptable to the appropriate ethics committee) in a modern abattoir. In the second group (ES; n=10) animals were electrically stunned. In the third group (PS; n=10) animals were stunned with percussive captive bolt. Meat quality was assessed by examining muscle glycogen concentration, pH and WHC. Also cooking loss, texture parameters and consumer sensory properties were assessed at 24 h, 4, 7 and 14 days post mortem. Meat colour as L^*, a^*, b^*, C^*, h^* values were evaluated at 0, 48 h, 3, 5, 7, 9 and 14 days post mortem. Pre-slaughter handling affected muscle glycogen concentration (P<0.05). Animals in electrical and percussive captive bolt stunned groups had higher muscle glycogen concentrations compared to animals in the non-stunned group (P<0.05). Although pre-slaughter handling did not affect significantly pH_{24 h} and WHC, differences were significant for cooking loss, colour coordinates and texture parameters at some storage times. For all sensory attributes (odour, flavour, tenderness and overall acceptability) at all ageing periods (24 h, 4, 7 and 14 days) the percussive stunned (PS) group was significantly superior to the non-stunned (NS) group. The electrically-stunned (ES) group also tended to be superior to the NS group although not all differences were statistically significant. These results indicate that percussive captive bolt stunning of cattle improved meat quality compared with cattle electrically stunned using head only tongs and those non stunned under approved Turkish slaughter procedure.     

Impact of muscle type and sodium chloride concentration on the quality, sensory, and instrumental color characteristics of solution enhanced whole-muscle beef

Beef biceps femoris (n = 10; muscle sections, n = 20; BF), infraspinatus (n = 10; muscle sections, n = 20; IS), and longissimus (n = 10; muscle sections, n = 20; LM) muscles were utilized to evaluate the effect of enhancement with phosphate and varying levels of sodium chloride in beef muscles differing in composition and palatability. Muscles were untreated or solution enhanced to 112% of raw product weight with sodium tripolyphosphate at 0.4% of product weight (STPP), or STPP and sodium chloride (NaCl) at 0.5%, 1.0% or 1.5% of product weight. There was a quadratic relationship (P = 0.04) for percent free water to decrease and a linear relationship (P < 0.01) for cook yield to increase as the level of NaCl increased. The IS steaks required less (P < 0.05) shear force than either the BF or LM, with the BF and LM having similar (P > 0.05) shear force values. There was a linear relationship (P < 0.01) for shear force values to decrease with increasing salt concentration. Steaks from all four enhancement treatments had lower (P < 0.05) shear force values than untreated steaks. Sensory overall tenderness ratings revealed that the IS and LM were similar (P > 0.05) and superior (P < 0.05) to the BF in tenderness. Steaks enhanced with STPP and 0.5%, 1.0%, or 1.5% NaCl all were rated more tender (P < 0.05) than untreated or STPP-only treated steaks. The BF exhibited the lowest (P < 0.05) L* (lightness) and a* (redness) values, as well as decreased (P < 0.05) vividness. The LM generally exhibited superior color to the other two muscle types. There was a linear relationship (P < 0.01) for L*, a*, b* (yellowness) values, and vividness to decline with increasing salt concentration, but steaks enhanced with STPP and 0.5% NaCl were similar (P > 0.05) in a* values and vividness to untreated steaks. These results suggest that across three different muscles varying in composition and palatability, enhancement with 0.4% STPP and 0.5% NaCl allowed for improvements in palatability while minimizing the color deterioration associated with phosphate/salt enhancement.     

Lipid oxidation in lamb meat: Effect of the weight, handling previous slaughter and modified atmospheres

This study examined the effect of pre-slaughter handling (electrical, gas (CO₂) or non-stunning) on lipid oxidation (as thiobarbituric acid reactive substances, TBARS; in the unit of mg malondialdehyde/kg⁻¹ of meat) of Spanish Manchega breed lamb meat, at 24 h and at 7 days post-mortem. Lambs were slaughtered at two different weights (light (L), 25 kg, vs. suckling (S), 12.8 kg). In general gas-stunned lambs had lower lipid oxidation (P < 0.001), and it was higher (P < 0.001) in light lambs compared to suckling lambs. In both groups (S and L), malondialdehyde level increased with time (P < 0.001), although this increase was lower (P < 0.05) in gas-stunned suckling lambs.

In addition, we evaluated the effect of stunning methods (TS: electrical vs. gas) and the weight (L vs. S) on lipid oxidation values in samples packed in different types of modified atmosphere (MA: A: 70%O₂ + 30%CO₂; B: 69.3%N₂ + 30%CO₂ + 0.7%CO; C: 60%N₂ + 40%CO₂) at 7, 14 and 21 days post-packing. Values were higher in samples with MA-type A and lower in B and C types (P < 0.05). A significant interaction (P < 0.001) weight × TS was observed and the lowest rates of TBARS were found in the samples of light lambs stunned with gas and packed under anaerobic conditions (MA-B and C).     

Influence of storage period and packaging method on sliced dry cured beef "Cecina de Leon": Effects on microbiological, physicochemical and sensory quality

Quality aspects of sliced dry-cured beef “Cecina de León” preserved in vacuum and gas mixtures (20%/80% CO₂/N₂ and 80%/20% CO₂/N₂) were studied. The evolution of microbiological, physicochemical and sensory parameters were analysed during storage (210 days) at 6 °C. Although microbial counts at 60 days of the gas-packaged samples were lower than the vacuum-packed ones, they were never higher than the spoilage limit (7 log ufc/g). A slight increase (p < 0.05) in pH was observed throughout storage of “Cecina de León” packaged under vacuum and in gas mixtures. However, a decrease (p < 0.05) in a_w was observed during storage of “Cecina de León” packaged under vacuum but a_w did not vary (p > 0.05) during storage in the gas-packaged samples. No changes were observed (p > 0.05) in lightness (L^*), redness (a^*) and yellowness (b^*) in vacuum and gas packaged samples during storage. However, sensorially evaluated colour showed lower values in gas packaged samples during 30 days storage. This difference was decisive in establishing the shelf-life of “Cecina de León” slices preserved in gas mixtures (20%/80% CO₂/N₂ and 80%/20% CO₂/N₂). Therefore, from a microbiological point of view, gas mixtures are more effective in extending the shelf-life of “Cecina de León” slices. It is concluded that vacuum packaging allows longer storage than gas-packaging as it maintains a good visual appearance of “Cecina de León”, the main parameter in consumers’ perception of meat quality.     

High voltage electrical stimulation enhances muscle tenderness, increases aging response, and improves muscle color from cabrito carcasses

Our study examined high and low voltage electrical stimulation and postmortem storage as strategies to improve tenderness and lean color in cabrito carcasses. Boer cross (n=60) kids were assigned to either high (550 V), low (20 V), or no electrical stimulation treatments. No differences in muscle temperature were observed between treatments at any time measured. Muscle pH declined fastest in high voltage treated carcasses. High voltage electrical stimulation slightly increased (P<0.05) b^* and a^* in the M. gluteus medius and tended to increase L^* and b^* (P=0.06 and 0.11, respectively) values in the M. longissimus thoracis. Electrical stimulation had no effect on myofibril fragmentation at 1-, 3-, or 14-d postmortem or sarcomere length. High voltage electrical stimulation increased (P<0.05) tenderness at 1- and 3-d postmortem, but not at 14-d postmortem. Aging for 3 d did not affect tenderness regardless of stimulation treatment, but aging time for 14 d improved (P<0.05) tenderness. These data indicate that high voltage electrical stimulation and 14 d aging were effective in improving the tenderness of meat from cabrito carcasses.     

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.     

Influences of dietary conjugated linoleic acid (CLA) and total lysine content on growth, carcass characteristics and meat quality of heavy pigs

To assess the effects of dietary CLA, lysine and sex on performance, blood metabolites, carcass characteristics, meat quality and skeletal development, seventy-two pigs (initially 105.3 ± 6.6 kg live weight) barrows and gilts, were assigned to one of four diets in a 2 × 2 × 2 factorial arrangement. The diets contained 0% or 0.75% CLA, and 0% or 0.16% of l-lysine–HCl. All pigs were slaughtered at an average weight of 153.4 ± 11.0 kg. Neither CLA nor lysine supplementation influenced growth, blood metabolites or carcass characteristics. CLA reduced (P < 0.05) pH₂₄ and increased (P < 0.01) yellowness (b^*) of the Longissimus muscle. Lysine increased (P < 0.01) pH₂₄ and reduced (P < 0.01) muscle ash content. CLA reduced (P < 0.05) collagen synthesis, and lysine increased (P < 0.05) collagen synthesis in Longissimus muscle, but no influence on intramuscular collagen maturity or muscle hydroxylysylpyridinoline crosslink concentration were observed. In addition, metacarpal bone diameter was reduced (P < 0.05) by CLA. Barrows had higher ADG, final weight (P < 0.01), carcass weight, lean percentage (P < 0.05), serum cholesterol (P < 0.05) and triacylglycerol (P < 0.001) than gilts. Metatarsal diameter was larger in gilts than barrows (P < 0.05).     

The effects of antioxidant combinations on color and lipid oxidation in n-3 oil fortified ground beef patties

This study was carried out to determine an effective combination of chelators, reductants and free radical scavengers for enhancing color stability and minimizing lipid oxidation in muscle foods fortified with n − 3 fatty acids. Chelators (sodium tripolyphosphate, STPP; sodium citrate, CIT), reductants (sodium erythorbate, ERY) and radical scavengers (butylhydroxyanisole, BHA; mixed tocopherols from two different sources, 30 or 95TOC; rosemary extract, ROSE) were incorporated in various combinations into ground beef (15% fat) with or without n − 3 oil fortification (n = 8). Individually, STPP and CIT had no significant effect on a* values except day 4, but showed higher a* values when combined with ERY (STPP + ERY and CIT + ERY) (P < 0.05). CIT had lower hue angle values than STPP on days 4 and 6, but CIT + ERY showed more discoloration than STPP + ERY (P < 0.05). CIT + ERY showed less lipid oxidation than CIT alone (P < 0.05), whereas there was no difference between STPP and STPP + ERY. CIT + ERY + ROSE demonstrated higher a* values than CIT + ERY + 95TOC on days 4 and 6 (P < 0.05); there was no difference between ROSE and 95TOC groups when n − 3 oil was incorporated into ground beef patties (P > 0.05). The combination of ROSE and ERY appeared to be effective in slowing the decline of a* values. All antioxidant combinations were effective at delaying lipid oxidation when compared to CON or n − 3. A combination of CIT, ERY and ROSE was most effective for stabilizing color and delaying lipid oxidation.     

The impact of lactic acid concentration and sodium chloride on pH, water-holding capacity, and cooked color of injection-enhanced dark-cutting beef

The objectives of this study were to evaluate the effect of enhancement with 0.5%, 1.0%, 1.5%, or 2.0% lactic acid (LA), with or without 0.5% salt (NaCl), on pH, water-holding capacity, and resultant cooked color of dark-cutting (DC) beef. The pH of DC sections treated with LA decreased (P < 0.05), whereas water-holding capacity (WHC) increased (P < 0.05) with increasing concentrations of LA. Sensory panelists noted an increase (P < 0.05) in the degree of doneness (less pink internal color), whereas, a^* and chroma values were lower (P < 0.05), and hue angles were greater (P < 0.05), indicating the internal color of LA-treated DC sections was less red and appeared more well-done. Also, 630:580 nm reflectance ratios were similar (P > 0.05) among DC steaks treated with 0.5% and 1.0% LA and normal pH (NDC) steaks, likely caused by an increase (P < 0.05) in myoglobin denaturation in LA-enhanced DC steaks. These results indicate that the use of LA can reduce postmortem muscle pH and alter the cooked color of DC beef, ultimately resulting in a deletion of the persistent pinking condition.