To What Extent Do Low-Voltage Electrostatic Fields Play a Role in the Physicochemical Properties of Pork during Freezing and Storage?

Low-voltage electrostatic fields (LVEF) are recognized as a new technology that can improve the quality of frozen meat. To determine the extent to which LVEF assistance affects the quality of frozen pork for long-term storage, pork was frozen and stored at -18 and -38 °C for up to 5 months. Water-holding capacity, muscle microstructure, and protein properties were investigated after up to 5 months of frozen storage with and without LVEF assistance. In comparison to traditional -18 and -38 °C frozen storage, LVEF treatment inhibited water migration during frozen storage and thawing. As a result, thawing losses were reduced by 15.97% (-18 °C) and 3.38% (-38 °C) in LVEF-assisted compared to conventional freezing methods. LVEF helped to maintain the muscle fiber microstructure and reduce muscle protein denaturation by miniaturizing ice crystal formation by freezing. As a result of this study, LVEF is more suitable for freezing or short-term frozen storage, while a lower temperature plays a more significant role in long-term frozen storage.

Genetic parameter estimates for sensory and meat quality traits measured at 3 and 29 days of aging of beef from Canadian crossbred cattle

Genetic parameters were estimated for objective and subjective traits assessed after 3 and 29 days aging in meat samples of 1154 commercial beef cattle. Meat attributes [Warner-Bratzler shear force (WBSF), intramuscular fat (IMF), and pH] and sensory traits [flavor intensity (FI), off-flavor (OF), connective tissue (CT), overall tenderness (OT), sustained juiciness (SJ), and overall palatability (OP)] were available. The animal mixed model used included additive genetic and residual effects as random effects, contemporary group as fixed effect and genomic breed composition and slaughter age as covariates. Genetic parameters were estimated using airemlf90 software and single-step genomic BLUP. Heritability estimates for OT (3 and 29 d), OP (3 d) and OF (29 d) were of moderate magnitude ranging from 0.18 ± 0.07 to 0.31 ± 0.07. Heritabilities were negligible or of low magnitude for all other sensory traits with values ranging from 0.03 ± 0.05 to 0.14 ± 0.07. Among objectively measured traits, the estimate of heritability for meat pH was moderate at day 3 (0.20 ± 0.08) and negligible at 29 (0.00 ± 0.05). For IMF and WBSF the heritability estimates were 0.43 ± 0.09 and 0.54 ± 0.09, and 0.22 ± 0.07 and 0.19 ± 0.07 for day 3 and 29, respectively. Genetic correlations between days for each sensory trait tended to be of high and positive magnitude ranging from 0.54 ± 0.60 to 0.99 ± 0.28. Genetic and phenotypic correlations of subjectively assessed traits were consistent in direction and magnitude with WBSF (negative) and IMF (positive) suggesting that genetic selection based on objectively measured traits can be used for meat quality improvement and to increase consumer satisfaction. In addition, selection can be implemented using sensory traits collected after 3 days of aging.

The effect of modified atmosphere packaging at an early postmortem stage on lamb meat quality during subsequent aging

This study explores the influence of modified atmosphere packaging (MAP) on fresh lamb meat quality with respect to gas concentration, rigor state, and post-mortem aging time. A comparison was done for the quality characteristics of lamb Longissimus thoracis lumborum chops that had been packaged separately in air, 75%O2  + 25%CO2 MAP or 50%O2  + 50%CO2 MAP at 1, 6, and 24 h post-mortem and then stored for 6, 12, 24, 72, and 144 h post-mortem, and the quality of lamb chops had been evaluated at each post-mortem period separately. Chops packaged at 1 and 6 h post-mortem in MAP had reduced pH decline, less purge loss, and enhanced redness at early post-mortem storage times. Lamb color stability was evidently greater in 75%O2  + 25%CO2 MAP than in 50%O2  + 50%CO2 MAP during the early storage period when a* and R630/R580 were taken into account. Shear force values were lowest in lambs packaged at 1 h post-mortem with 75%O2  + 25%CO2 MAP at 12 h post-mortem and then increased until 72 h post-mortem, suggesting that rigor has been delayed by such a high O2 MAP. Thus, fresh lamb quality was maintained most effectively when packaged at 1 h post-mortem in 75%O2  + 25%CO2 MAP for consumption at 12 h post-mortem. The exact mechanisms and optimization of MAP based on Chinese retail conditions should be considered in future studies. PRACTICAL APPLICATION: In this study, three slaughter patterns in the meat industry involving boning immediately after dressing (hot-boning) and chilling for a short period (warm-boning) or overnight (cold-boning) are considered, as well as the behavior of non-immediate consumption after purchase. Modified atmosphere packaging provides an effective preservation of early post-mortem muscles with enhanced color stability, water holding capacity, and texture during refrigerated storage. This could provide new insights into how to process lamb muscles in the early post-mortem period to improve and stabilize lamb quality.

Bioactive peptides in hydrolysates of bovine and camel milk proteins: A review of studies on peptides that reduce blood pressure, improve glucose homeostasis, and inhibit pathogen adhesion

The prevalence of diet-related chronic conditions including hypertension and cardiovascular disease, and diabetes mellitus has increased worldwide. Research regarding the use of food-derived bioactive peptides as an alternative strategy to mitigate chronic diseases is on the rise. Milk is recognized as one of the main dietary protein sources for health beneficial bioactive compounds. Hundreds of in vitro studies have suggested that milk-derived bioactive peptides offer multiple biological and physiological benefits, and some but not all were confirmed in vivo with animal models for hypertension, hyperglycemia, and pathogen adhesion. However, only a limited number of health benefits have been confirmed by randomized clinical trials. This review provides an overview of the current clinical studies that target hypertension, postprandial hyperglycemic, and adhesion of enteric pathogen with bioactive peptides derived from bovine and camel milk, with a focus on the factors affecting the efficacy of orally ingested products.

Muscle Fiber, Connective Tissue and Meat Quality Characteristics of Pork from Low Birth Weight Pigs as Affected by Diet-Induced Increased Fat Absorption and Preferential Muscle Marbling

This study investigated how birth weight differences in piglets affected carcass and muscle fiber properties as well as meat quality at slaughter. Within litters, piglets were grouped according to their birth weight as either normal (NBW; 1.62-1.73 kg) or low (LBW; 1.18-1.29 kg). At 5 weeks of age, NBW piglets were randomly transitioned to control (C) or isocaloric high fat diets derived from non-dairy (HF), while LBW piglets were randomly transitioned to high fat diets derived from non-dairy (HF) or dairy sources (HFHD). Piglets were reared in individual pens under standardized housing and feeding conditions. Live weight was recorded weekly, and pigs were slaughtered at 12 weeks of age. Hot carcass weights, dressing percentages, lean meat yield, and primal cut proportions were determined. The m. longissimus thoracis was collected from the right side of the carcass for measurement of physical and chemical properties of meat and muscle fiber characteristics. Results indicated that LBW pigs compensated for their live weight compared to NBW pigs at 6 weeks of age. The mean muscle fiber diameter of LBW-HFHD group is significantly higher than NBW-C and NBW-HF group, and the type I muscle fiber diameter is significantly higher than NBW-C group. Dairy fat inclusion in LBW pig diet reduced carcass back fat thickness. This increased the calculated lean meat yield to be comparable to that of NBW pigs fed a commercial diet. Incorporating dairy-sourced high-fat into LBW pigs' diets appears to be an effective strategy for producing carcasses equivalent to NBW pigs.

Effects of alternating electric field assisted freezing-thawing-aging sequence on longissimus dorsi muscle microstructure and protein characteristics

The current study investigates the influence of alternating electric field (AEF)-assisted freezing-thawing-aging sequence on the muscle microstructure and myofibrillar protein characteristics. Three treatments were used for longissimus dorsi (LD) muscle: only aging (OA), freezing-thawing-aging sequence (FA) and AEF-assisted freezing-thawing-aging sequence (EA). Compared with the FA and EA groups, the OA group showed considerably fewer cracks between muscle fibers and maintained the integrity of the Z-line as observed using scanning and transmission electron microscopy, respectively. Furthermore, the EA treatment effectively decreased myofibrillar fragmentation, myofibrillar protein aggregation, and protein oxidation, as shown by the myofibrillar fragmentation index, turbidity, and total sulfhydryl concentration. Analysis of surface hydrophobicity and the Fourier transform infrared, UV absorption, and fluorescence spectrums indicated that AEF minimized the alterations of protein secondary and tertiary structure alterations during aging after freezing.

Contribution of intramuscular connective tissue and its structural components on meat tenderness-revisited: a review

The tenderness of meat influences consumers' perceptions of its quality. Meat tenderness is a key quality characteristic that influences consumer satisfaction, repeat purchases, and willingness to pay higher prices for meat. Muscle fibers, connective tissues, and adipocytes are the main structural components of meat that contribute to its tenderness and texture. In the present review, we have focused on the role of connective tissue and its components in meat tenderness, specifically perimysial intramuscular connective tissue (IMCT) and its concept as an immutable "background toughness." The collagen contribution to cooked meat toughness can be altered by animal diet, compensatory growth, slaughter age, aging, and cooking. As well, progressive thickening of the perimysium leads to a progressive increase in shear force values in beef, pork, chicken, and this may occur prior to adipocyte formation as cattle finish in feedlots. Conversely, adipocyte accumulation in the perimysium can decrease cooked meat shear force, suggesting that the contribution of IMCT to meat toughness is complex and driven by both collagen structure and content. This review provides a theoretical foundation of information to modify IMCT components to improve meat tenderness.

Effects of alternating electric field during freezing and thawing on beef quality

Alternating electric field (AEF) technology was used during freezing-thawing-aging (FA) of beef aged for 0, 1, 3, 5 and 7 days. Color, lipid oxidation, purge loss, cooking loss, tenderness, and T₂ relaxation time were determined for frozen-thawed-aged beef with AEF (AEF + FA) or without AEF (FA) and compared to aged only (OA) controls. FA increased purge loss, cooking loss, shear force values and lipid oxidation (P < 0.05) but decreased a* values compared with AEF + FA treatment. It also exacerbated the spaces between muscle fibers and contributed to the transformation of immobile water to free water. AEF served to maintain meat quality by reducing purge loss, cooking loss and increasing meat tenderness and maintaining color and lipid oxidation only in steak that was frozen before aging. This most likely occurred due to AEF increasing the speed of freezing and thawing and by reducing the space between muscle fibers compared to FA alone.

Preferential deposition of dairy derived fatty acids in muscle tissue is partially due to the upregulation of CD36 in a low-birth-weight swine model

Metabolic syndrome is a worldwide health issue. Previous research has revealed that low-birth weight (LBW) swine fed a high-fat (HF) diet were susceptible to insulin resistance (IR) and developed a preferential intestinal lipid absorption, hypertriglyceridemia, and muscle steatosis. We hypothesized that fatty acid transporters such as CD36, FATP4, and FABP2 could potentially explain the development of these conditions. In addition, dairy-derived fatty acids have been shown to be valid biomarkers to assess dairy intake, which can be utilized to investigate muscle lipid deposition in LBW swine. The overall aim of this study was to delineate molecular transport candidates responsible for intestinal lipid absorption and muscle lipid deposition in LBW swine; and secondly to determine what dietary fatty acids might accumulate preferentially in pork muscle when consuming dairy products. At 5 weeks of age, normal birth weight (NBW) and LBW piglets were randomly assigned to three experimental diets: 1-chow diet, 2-HF diet, or 3-isocaloric HF diet supplemented with full fat dairy products. At 12 weeks of age, piglets were euthanized, and carcass, fasting plasma, biceps femoris and jejunum mucosal scrapings were collected. Results showed that HF-fed LBW swine exhibited early signs of IR (fasting glucose, P < 0.05; fasting insulin, P = 0.091; HOMA-IR, P = 0.086) compared with NBW-Chow, which were attenuated with increased dairy intake. Muscle samples from HF-fed LBW swine contained significantly more triglyceride compared to Chow-fed NBW swine (P < 0.05). Increased dairy intake significantly increased myristic acid (C14:0) and DPA (C22:5n3) relative to HF feeding alone (P < 0.05). All HF-fed LBW swine (regardless of dairy intake) exhibited an upregulation of CD36 expression (but not FABP2) compared with NBW littermates in both the small intestine and muscle (P < 0.05). Interestingly, increased dairy intake significantly increased the Canadian Lean Yield percentage in LBW swine fed an HF diet (P < 0.05). Findings from this study provide evidence on the mechanistic pathway of intestinal and muscle lipid metabolism in an innovative LBW swine model. We have also revealed that increasing dairy intake can enhance the incorporation of dietary long-chain polyunsaturated fatty acids into pork, as well as increasing the predicted lean yield of the carcass.

Effects of Alternating Electric Field Assisted Freezing-Thawing-Aging Sequence on Data-Independent Acquisition Quantitative Proteomics of Longissimus dorsi Muscle

This study was designed to investigate the differences in the proteomes of bovine Longissimus dorsi (LD) muscle during an alternating electric field (AEF)-assisted freezing-thawing-aging sequence based on a data-independent acquisition strategy. When compared to that of the only postmortem aging (OA) group, the meat quality of the freezing-thawing-aging sequence (FA) and AEF-assisted freezing-thawing-aging sequence (EA) groups showed a declining trend. However, the group assisted by AEF was significantly enhanced in color, water-holding capacity, and tenderness. Three hundred fifty-two proteins in LD muscle were differentially abundant proteins (DAPs) among FA, EA, and OA treatments. Furthermore, among the 40 DAPs in the FA versus EA comparison, 5 DAPs with variable importance in projection scores higher than 1 were identified as biochemical markers of beef quality. Bioinformatic analysis revealed that most of these proteins were involved in structural constituents of ribosome and catalytic activity. These results provide a basis for further understanding the quality of beef following a freezing-thawing-aging sequence assisted by AEF.

The Influence of Vacuum Packaging of Hot-Boned Lamb at Early Postmortem Time on Meat Quality during Postmortem Chilled Storage

To evaluate the effects of early postmortem vacuum packaging (VP) on meat quality during postmortem chilled storage, hot-boned lamb was vacuum-packaged at 1, 6, 12, 24, and 48 h postmortem and stored around 2°C until 168 h postmortem, with lamb packaged in plastic wrap as the control (aerobic packaging). Intramuscular pH decline was delayed when lamb was vacuum packaged at 1, 6, and 12 h postmortem (p<0.05). The lamb vacuum-packaged at 1 h postmortem (VP-1h group) had significantly lower shear force values and purge losses accompanied by lower free thiol group values than other treatments during postmortem storage and was also higher in extractable calpain-1 activity by 6 h postmortem (p<0.05). Free thiol group concentrations were significantly higher after VP at 6 and 12 h postmortem (p<0.05). Packaging lamb under vacuum very early postmortem produced the lowest shear force and purge loss, likely by slowing heat loss and muscle temperature decline, implying that lamb quality is improved by VP when applied very early postmortem. This was at the expense of protein oxidation, which was unrelated to other meat quality measurements, most likely because potential contracture during hot boning confounded its impact. Further research is required to understand the implications of the interaction between protein oxidation, VP, and hot boning on the acceptability of lamb.

Impact of genetic potential for residual feed intake and diet fed during early- to mid-gestation in beef heifers on carcass characteristics and meat quality attributes of their castrated male offspring

Carcass attributes of steers were examined for influences of selection for residual feed intake (RFI), and exposure to different levels of prenatal nutrition. Heifers characterized for RFI corrected for backfat were mated to bulls with genetic potential for either High-RFI or Low-RFI, such that the progeny were expected to be H/H or L/L RFI (sire/dam). Pregnant heifers were assigned to a low diet (Ldiet; 0.40 kg/d ADG), or moderate diet (Mdiet; 0.57 kg/d ADG), from 30 to 150 days of gestation, after which all heifers were managed similarly. Steer offspring (n = 23) were also managed similarly until slaughter. Dressing percentage of steers from H-RFI dams/sires exposed to Ldiet during gestation was lower than all other groups (P = 0.02). Marbling was greater for steers from H-RFI parents, as was fat content of longissimus thoracis et lumborum and triceps brachii (P ≤ 0.02). Results suggest that parental selection for RFI and prenatal maternal diet can influence carcass characteristics of progeny.

A genome-wide case-control association study of dark cutting in beef cattle

The genetic architecture of dark cutting was investigated with a case-control genome-wide association study on two groups of beef cattle analyzed separately and together (combined group). Groups I (n = 64) and II (n = 150) were genotyped using the 70K GeneSeek Genomic Profiler for Beef Cattle-HD and the 50K Illumina BovineSNP50v2 BeadChip, respectively. Dark cutting was analyzed as a binary trait (case versus control) using logistic regression in an additive model implemented in PLINK version 1.9. Significant loci were not identified when correcting for multiple testing (false discovery rate), suggesting that the trait is not controlled by genes with big effects, or the sample size was not large enough to detect these major genes. Regions harbouring single-nucleotide polymorphisms (SNPs) with a raw p < 0.01 using 1 MB window were analyzed for gene function using the ingenuity pathway analysis. For groups I, II, and the combined group, 449, 301, and 191 SNPs were identified, respectively. Genes identified were involved in pyruvic acid modification and release, 2-deoxyglucose clearance and disposal, sucrose recognition, energy production, and metabolism of carbohydrate. Although detected SNP associations require validation in a large population, results suggested the possibility for marker-assisted or genomic selection of beef cattle to reduce dark cutting.

Relationship between meat quality and intramuscular collagen characteristics of muscles from calf-fed, yearling-fed and mature crossbred beef cattle

Intramuscular Ehrlich Chromogen (EC) and pyridinoline (Pyr) concentrations in the gluteus medius (GM) and semitendinosus (ST) from crossbred Angus calf- (n = 14) and yearling-fed (n = 14) steer and mature cow (MC, n = 12) carcasses were related to collagen and intramuscular connective tissue (IMCT) thermal stability and peak Warner-Bratzler shear force (WBSF). In both muscles, Pyr density was greater in MC, while EC concentrations were comparable in calf- and yearling-fed steer muscles and lowest in MC muscles. Thermal denaturation temperature and enthalpy of IMCT were highest in both muscles when from MC, although only total collagen was correlated with WBSF in calf fed-yearling fed steer data. Results confirmed that EC concentration contributed to collagen thermal stability in steer muscles, but decreased it in MC muscles, while Pyr was consistently associated with collagen thermal stability.

Meat and sensory quality of major muscles from Angus, Charolais, and Angus crossbred steers with high and low residual feed intake

Effects of residual feed intake (RFI) and genetic group on growth, carcass, and meat quality characteristics of bovine longissimus lumborum (LL), triceps brachii (TB), semimembranosus (SM), and gluteus medius (GM) muscles were investigated using 72 purebred Angus, purebred Charolais, and Angus crossbred steers (n = 24 per genetic group) classified as either high (inefficient) or low (efficient) RFI (n = 12 high and low RFI steers within genetic group). There was no RFI effect (P > 0.05) on growth, carcass, and meat quality measurements except high RFI steers had the highest dry matter intake (P < 0.05), and low RFI TB was rated as having reduced beef flavour intensity and sustained juiciness (P < 0.05). Purebred Angus and Charolais LL and GM had lower shear force values (P < 0.05) than Angus crossbreds and ageing reduced mean shear force values except in TB. For TB, SM, and GM, Angus crossbred steers had the highest mean beef flavour intensity scores, and Charolais SM and TB were less tender than those of Angus crossbred (P < 0.05). Overall, RFI did not influence most meat quality traits; therefore, low RFI animals may contribute to reducing feed costs or environmental impact without compromising meat quality and palatability.

PSV-31 Mechanisms and biochemical pathways affecting the eating quality of Triceps brachii muscle

Twenty-four beef steers (Angus, Charolais and Angus crossbred) were used to test the hypothesis that phenotypic measurements of meat quality attributes and intramuscular connective tissue characteristics will be related to the differences in the expression level of genes involved in the synthesis and degradation of collagen. Triceps brachii muscles from steers with low and high intramuscular collagen solubility at 3 days post mortem (dpm) were selected within each breed type for candidate gene analysis. Expression levels of 27 candidate genes were evaluated using quantitative real-time polymerase chain reaction (RT-qPCR) and the mean differences in expression between candidate and control (18s RNA) genes were calculated. Analysis of variance indicated that breed type had significant effects (P &lt; 0.05) on expression of genes related to collagen types I, V, and VI (COL1A1, COL5A1 and COL6A1), fibroblast growth factor (FGF), lysyl hydroxylase (LH), matrix metalloproteinases (MMP) 1, 8 and 13, prolyl 4-hydroxylase (P4HA1), SMAD (2, 3 and 7), and tissue inhibitor of MMPs (TIMP). Collagen heat solubility had no effect on gene expression (P &gt; 0.05), although there was a significant interaction between breed type and collagen solubility (P &lt; 0.05) for COL3A1, FGF2, MMP13, and SMAD 6 expressions. Candidate gene expression levels were correlated to intramuscular pH, 3 and 13 dpm Warner-Bratzler shear force (WBSF), total intramuscular collagen, and collagen heat solubility at 3 and 13 dpm. Negative correlations (P &lt; 0.05) existed between FGF1 and 13 dpm soluble collagen (r = -0.44), MMP8 and total collagen (r = -0.55) and MMP13 and wet perimysium weight (r = -0.46). Positive correlations (P &lt; 0.05) existed between FGF1 and 3dpm WBSF (r = 0.44) and, TIMP3 and 3 dpm WBSF (r = 0.33). Results indicated genes associated with increased collagen synthesis and inhibition of MMPs were related to increased beef toughness.

PSVIII-32 Estimates of genetic parameters for sub-primal and meat quality traits in Canadian commercial crossbred swine populations

The hypothesis that genetic relationships exist between loin muscle collagen characteristics and sub-primal and meat quality traits was tested. Data from 500 pigs from crosses between Duroc sires and hybrid Large White ✕ Landrace sows with pedigree back to about eight generations were used. Significant fixed effects (slaughter group and company) and a random additive effect were fitted in bivariate animal models to estimate phenotypic and genetic correlations using ASReml 4.1. Moderate heritabilities were obtained for sub-primal traits ranging from 0.21 for bone weight to 0.44 for loin muscle weight with a low estimate of 0.10 being obtained for loin weight. Meat quality traits were low to moderately heritable with the highest estimate being found for intramuscular fat (0.42). The heritability estimates for percentages of heat soluble and insoluble collagen were 0.12 and 0.15, respectively, while 0.33 was found for total collagen. Moderate to relatively high heritabilities imply the possibility of improving these traits through selective breeding. In general, moderate to high phenotypic and genetic correlations were obtained for sub-primal traits, whilst meat quality traits had moderate phenotypic and moderate to high genetic correlations. Strong negative genetic correlations between moisture traits and fat traits and a further negative correlation between fat and muscling traits were estimated confirming that selecting for improved muscling over time can negatively affect fat traits and indirectly decrease meat eating quality. The strong genetic correlation between pH and L* (-0.95) suggested possible pleiotropic gene effects on these traits. Warner-Braztler shear force (WBSF) had moderate genetic correlations with insoluble collagen (0.42) and soluble collagen (-0.38) suggesting a potential relationship between some of the genes impacting these traits. Genetic correlations between WBSF and collagen characteristics indicate that despite the relative youthfulness of pigs at slaughter, genetic selection for collagen solubility may decrease pork toughness.

Consumer Sensory Comparisons Among Beef, Horse, Elk, and Bison Using Preferred Attributes Elicitation and Check-All-That-Apply Methods

Despite their nutritional benefits, consumption of red meat from alternative sources such as bison, elk, and horse is low when compared to beef. Sensory attributes and drivers of liking were identified for these meats using the Preferred Attributes Elicitation (PAE) and Check-All-That-Apply (CATA) methods. For the PAE study, 25 panelists evaluated beef, horse, bison, and elk meats in three different group sessions (n = 7, 7, and 11), whereas 63 panelists participated in the CATA study. Consumers in both PAE and CATA studies associated horse meat with dry and fibrous appearance, whereas beef was associated with meaty/beefy flavor and aroma: bison with metallic and livery aroma and intense aftertaste and elk meat with livery, fishy, metallic flavor, musky aroma, and bloody aftertaste. Penalty analysis on the CATA data identified similar drivers of meat liking as the PAE groups. The attributes were juiciness, meaty/beefy aroma, tender texture, meaty/beefy flavor, and mild flavor and aroma. Attributes with significantly negative mean impact on liking were dryness, tough texture, livery flavor, and aftertaste. Association of these attributes with horse and elk meats has implication on drivers of dislike for these meat types. Cluster analysis identified a small group of consumers with preference for horse and elk meats, and this may present niche market opportunities for these meat types. Results showed that the PAE method was comparable to CATA for the evaluation of meat from different species and for identification of drivers of liking and that both methods are effective for meat sensory characterization. PRACTICAL APPLICATION: Lean red meat from unconventional sources such as elk, bison, and horse has unique sensory attributes that may influence acceptance. This study characterized the sensory attributes of these meats and their impact on liking using two rapid consumer descriptive profiling methods-PAE and CATA. Undesirable flavor and aftertaste attributes were identified as the major drivers of disliking for these unconventional meats. Both methods gave similar description of the samples, thus confirming the suitability of PAE for descriptive meat profiling by consumer panels.

Cattle production practices and the incidence of dark cutting beef

The effects of cattle sex, production system, growth promotant use, slaughter season, carcass phenotype, and pre-slaughter cattle management on the incidence of beef carcasses grading Canada B4 (dark cutting) were investigated using two data sets (A, n = 2009, and B, n = 86,408) containing data from cattle that produced Canada Prime, AAA, AA, A, and B4 carcasses. The probability of producing a Canada B4 carcass was greater (P < .0001) for heifers than steers in both data sets, with the likelihood of dark cutting decreasing with increased carcass weight in heifers in data set B. The incidence of dark cutting was increased (P < .0001) in Winter-born calf-fed (WC) and Fall-born calf-fed (FC) heifers. Production system and phenotype appear to interact to influence the incidence of dark cutting.

MEAT SCIENCE AND MUSCLE BIOLOGY SYMPOSIUM: BIOLOGICAL INFLUENCERS OF MEAT PALATABILITY: Production factors affecting the contribution of collagen to beef toughness1,2

Intramuscular collagen may affect the value of meat by limiting its tenderness and cooking convenience. Production factors such as age of animal at slaughter, the use of steroids and beta-adrenergic agonists as growth promotants, and cattle breed may affect the contribution of collagen to beef quality. Recent research has indicated that concentrations of the mature collagen cross-link pyridinoline (PYR) are positively correlated with Warner-Bratzler shear force (WBSF) and animal age at slaughter, while contribution of the concentration of a second mature collagen cross-link Ehrlich's Chromogen (EC) to beef toughness declines with cattle age. Cattle breed influences total collagen content of muscle due to differing rates of maturation among breeds. Growth promoting technologies do not appear to affect collagen solubility, but do influence PYR and EC densities and concentrations in some beef muscles. Concentrations of PYR and EC do not account for all the variation in collagen heat solubility in beef muscles, nor do advanced glycation end products given the relative immaturity of cattle at slaughter. In light of this, other collagen cross-links such as heat-stable divalent cross-links may warrant reconsideration with regard to their contribution to cooked beef toughness.

Efficacy of genetic parameter estimation of pork loin quality of crossbred commercial pigs using technological quality measurements of frozen and unfrozen product

Meat quality characteristics have been measured on fresh and previously frozen meat as part of genetic studies, but freezing of meat may alter its quality characteristics and, therefore, the relationships between genetic components and meat quality measurements. Pork color, pH, and drip loss measurements performed on longissimus dorsi from the carcasses of 2027 crossbred commercial pigs when either fresh or thawed after frozen storage were used to estimate genetic parameters using a bivariate animal model in ASReml. Meat quality traits measured before and after freezing and thawing were significantly (P < 0.0001) different from each other and intramuscular crude fat content exerted a large effect on the magnitude of change in L* (lightness) and b* (yellowness). Meat quality measurements of fresh pork were moderately to highly heritable except for b* and pH, with heritability estimates for L*, pH, and drip loss greater when measured on fresh rather than frozen-thawed samples. Considering heritability and genetic correlation results, we concluded that whilst either fresh or frozen-thawed pork samples can be used for fresh pork L*, a* (redness), and b* measurements, pH, and possibly drip loss should be measured in fresh pork samples rather than in those that have been frozen-thawed during genetic selection for fresh pork quality.

Role of myofibers, perimysium and adipocytes in horse meat toughness

Horse meat is a good source of iron with low cholesterol but consumers consider tenderness most important when purchasing meat. Myofibers and intramuscular connective tissue, the main structural components of muscle, play major roles in meat toughness. The effects of myofibers and perimysium characteristics on Warner-Bratzler Shear Force (WBSF) values of horse semimembranosus were investigated on muscles previously assessed as tough (mean WBSF 68.87 ± 3.21 N, n = 8) or tender (mean WBSF 46.21 ± 2.27 N, n = 8). Mean Type IIA myofiber diameter was significantly greater in tender than in tough muscles. Secondary thick perimysium was thicker and collagen fibers more loosely arranged in tender muscles than in tough. A negative correlation was observed between WBSF values and perimysium thickness and a trend between WBSF and intramuscular fat. Adipocytes in perimysium of tender muscles may have contributed to thickening of perimysium and loosened collagen fibers thus contributing to tenderness of the meat.

Removing Cross-Linked Telopeptides Enhances the Production of Low-Molecular-Weight Collagen Peptides from Spent Hens

The low-molecular-weight (LMW) peptides derived from collagen have shown a potential for various nutritional and pharmaceutical applications. However, production of LMW peptides from vertebrate collagen remains a challenge. Herein, we report a new method to produce LMW collagen peptides using pepsin pretreatment that removed cross-linked telopeptides in collagen molecules. After the pretreatment, the proportion of LMW collagen peptides (<1.4 kDa) that were obtained from pepsin-soluble collagen increased to 32.59% compared to heat-soluble collagen peptides (16.10%). Fourier transform infrared spectroscopy results indicated that telopeptide cleavage retained the triple-helical conformation of collagen. Liquid chromatography-tandem mass spectrometry analysis suggested that Gly-X-Y (X is often proline, while Y is either hydroxyproline or hydroxylysine) repeats were not the main factors that hindered the enzymatic hydrolysis of collagen molecules. However, cross-link quantification demonstrated that trivalent cross-links that included pyridinolines and pyrroles were the primary obstacles to producing small peptides from collagen of spent hens. This study demonstrated for the first time that removing cross-linked telopeptides could enhance the production of LMW peptides from spent hen collagen, which is also of interest to manufacturers who produce LMW collagen peptides from other vertebrate animals, such as bovids and porcids.

Instrumental meat quality characteristics associated with aged m. longissimus thoracis from the four Canadian beef quality grades

Canadian beef is quality graded to characterize the potential eating quality of the cooked product. Instrumental meat quality characteristics of 48 m. longissimus thoracis (LT, rib eye) from four Canadian beef grades (Canada A, AA, AAA, and Prime, n = 12) before and after an additional 14-d aging were compared using a split plot design with grade, aging, and their interaction as fixed sources of variation. Mean percentage intramuscular fat was greatest in Canada Prime muscle and least in Canada A and AA muscles (P < 0.0001), whereas mean percentage drip loss was lower in Canada Prime muscle than in muscle from all other grades (P = 0.0348). Canada Prime and AAA muscles were redder and yellower than muscles from other grades even after aging (P < 0.03), which may be associated with increased fat content and indicative of accelerated myoglobin oxidation and increased myoglobin oxygenation. Shear force was not different among the Canada grades, although the differences between Canada AA cooked beef LT and that of Canada Prime and AAA carcasses approached significance (P = 0.0993). Results indicated that Canada quality grades did not differentiate beef on cooked product tenderness, substantiating that muscle compositional characteristics alone define beef grade advantages.

Can potential for dark cutting be predicted by phenotype? Relationship between sex, carcass characteristics, and the incidence of dark cutting beef

Recent research indicated that reduced carcass muscling and weight are associated with beef dark cutting. Existing data from a single farm (44 heifers, 136 steers) from three normal beef quality grades (Canada AAA, AA, A) and the dark cutting grade (Canada B4) (n = 35, 106, 28, and 11, respectively) were used to identify relationships between sex, live animal, and carcass characteristics and the incidence of dark cutting. Categorical modelling showed a trend (P = 0.106) for heifer carcasses to have a greater probability [11.36 ± 4.78% standard error of the mean (SEM)] of dark cutting than carcasses from steers (4.4 ± 1.76% SEM). Mixed model analysis of variance indicated dark cutting heifers weighed less than cattle from normal grades at weaning (P = 0.0229) and slaughter (P = 0.0295). Logistic regression revealed that the probability of each carcass grade occurring was influenced by dry matter intake (DMI) (P = 0.0034), and the probability of dark cutting was lowest (P = 0.0286) in cattle with carcasses greater than 300 kg. Results suggested that cattle at risk of dark cutting may be identified by weight, average daily gain (ADG), and feed intake.

Measurement of the abundance of choline and the distribution of choline-containing moieties in meat

Epidemiological studies identify meat as a major source of choline; however, the most comprehensive reference for food choline content, the United States Department of Agriculture (USDA) database for dietary choline, does not include values for meats of importance in some regions. In this work, the total choline and choline-containing moieties of 20 samples of meat were analyzed by LC-MS/MS; 16 samples analyzed are absent from the USDA database and 4 samples included for comparison. Average total choline for one serving (75 g) was 50 ± 12 mg, which was 82.6% ± 5.5% phosphatidylcholine. There was general agreement between total choline levels in the meats analyzed in this work and USDA values. A strong negative correlation (r = -0.777, p < 0.001) between total choline and fat content was found. This research added choline composition data to a food group that is a major source of choline and ultimately this data will assist in obtaining more accurate estimates of dietary choline.

Associations between single nucleotide polymorphisms in 33 candidate genes and meat quality traits in commercial pigs

This study aimed to evaluate the effects of single nucleotide polymorphisms (SNPs) in candidate genes for meat quality using a custom 96-SNP panel (Illumina Vera Code GoldenGate Assay) on 15 traits collected from 400 commercial pigs. Meat quality measurements included muscle pH, color (L*, a* and b*), drip loss, cooking loss, peak shear force and six sensory traits including appearance (outside and inside), tenderness, juiciness, flavor and overall liking as well as carcass weight and probe yield. Thirty-five SNPs with minor allele frequencies > 0.10 remained for the multimarker association using the GLM procedure of sas 9.2. Results showed that 20 SNPs were significantly associated with at least one of the traits with either additive or dominance or both effects (P < 0.05). Among these significant SNPs, five of them in ADIPOQ, FTO, TNF, LEPR and AMPD1 had an effect on more than three traits simultaneously; those in MC4R, CAST, DGAT1 and MYF6 had an effect on two traits, while the others were associated with one trait. The results suggest that these markers could be incorporated into commercial pigs for marker-assisted selection and breeding programs for carcass and meat quality trait improvement.

Influence of on-farm production practices on sensory and technological quality characteristics of pork loin

Quality of pork from pigs raised either traditionally (outdoor access or bedded settings with no sub-therapeutic antibiotics or growth promotants in feed) or conventionally (commercial indoor) was evaluated. Pork loins (m. longissimus thoracis et lumborum, LTL) from four hundred pigs from either traditional or conventional production systems (n=200) fed commercially formulated diets ad libitum were harvested at slaughter. Intramuscular crude fat content and lean color (L* and b*) values were significantly decreased in conventional pork loins. LTL from conventionally-raised pig carcasses showed increased (P<0.05) mean pH, moisture content and reduced cooking loss and shear force values and had increased tenderness and juiciness scores compared to those from traditionally-raised pig carcasses. Results indicated that pork from conventionally raised pigs was superior to that from traditionally raised pigs in terms of tenderness and juiciness, suggesting that consumers may value pork from traditionally raised pigs on the basis of factors other than eating quality and appearance.

Effect of temperature and pH on postmortem color development of porcine M. longissimus dorsi and M. semimembranosus

BACKGROUND

Purchasing pork that is boned within 1 h postmortem and not aged is customary in China, and final pork color would not be fully realized. The relationship between early postmortem, pre-rigor meat color and 24 h postmortem, post-rigor pork color was investigated and related to the rate of pH and temperature decline within the longissimus dorsi (LD) and the semimembranosus (SM) muscles of pork carcasses. Muscle color, pH and temperature were measured at 45 min and at 3, 9, 15 and 24 h postmortem in carcasses of F₂ White Duroc and Chinese Erhualian pigs.

RESULTS

Pork color at 45 min postmortem was not indicative of that at 24 h postmortem in LD and SM, although muscle pH values and temperature at 45 min postmortem were significantly correlated with the LD and SM ultimate color. High muscle pH was associated with decreased L*, whereas high muscle temperature increased L*. Muscle pH and temperature had little effect on a* and b* in LD and color evolution in SM.

CONCLUSIONS

Results indicated that meat color inspected shortly after slaughter does not reflect post-rigor meat quality.

Feeding flaxseed enhances deposition of omega-3 fatty acids in broiler meat portions in different manner

Feeding a diet containing 12% flaxseed for 36 d significantly increased the n-3 fatty acid deposition in broiler meat. Based on this study, consuming 100 g of such fatty acid-enriched breast meat, whole leg or wing, a total of 0.2, 1.6 and 2.0 g of n-3 fatty acids, including 10.4, 20.3 and 25.3 mg of docosahexaenoic acid, respectively, would be provided by each portion, which offers consumers an alternative to enhance their daily n-3 fatty acid intake.Key words: Flaxseed, n-3 fatty acid, broiler chicken

Enzyme addition facilitates the post-disease compensatory growth of broiler chickens challenged with Clostridium perfringens

In vitro incubation studies using a multicarbohydrase supplement showed a significant depolymerization of nonstarch polysaccharides (NSP) of soybean meal (SBM), canola meal and flaxseed meal, which was associated with the production of water-soluble NSP hydrolysis products. Effects of diet type and enzyme addition on growth performance of broiler chickens were investigated in a Clostridium perfringens challenge (109 CFU bird-1 on day 14) study. A total of 2640 male chickens were assigned to six treatments (wheat/SBM, unchallenged; wheat/SBM challenged; wheat/SBM + enzyme, challenged; wheat/flaxseed, unchallenged; wheat/flaxseed, challenged; wheat/flaxseed+enzyme, challenged). When compared with the wheat/SBM-based diets, birds fed flaxseed-containing diets had a decreased final body weight, an inferior overall feed conversion ratio (FCR), and an increased intestinal digesta viscosity (P < 0.01). Pathogen challenge caused mucosal lesions and increased (P < 0.05) the incidence of necrotic enteritis mortality with the highest mortality rate observed in birds fed the flaxseed diet without enzyme. Enzyme addition decreased (P < 0.05) the overall FCR from 1.88 to 1.77 and from 1.96 to 1.86 in challenged birds fed wheat/SBM and flaxseed-containing diets, respectively. In conclusion, feeding flaxseed had adverse effects on growth performance, and enzyme addition improved the nutritive value of flaxseed-containing diets, and facilitated the post-disease compensatory growth of chickens after C. perfringens challenge.Key words: Enzyme, flaxseed, Clostridium perfringens, broiler chicken

Gene expression profiling of muscle tissue in Brahman steers during nutritional restriction

Expression profiling using microarrays allows for the detailed characterization of the gene networks that regulate an animal's response to environmental stresses. During nutritional restriction, processes such as protein turnover, connective tissue remodeling, and muscle atrophy take place in the skeletal muscle of the animal. These processes and their regulation are of interest in the context of managing livestock for optimal production efficiency and product quality. Here we expand on recent research applying complementary DNA (cDNA) microarray technology to the study of the effect of nutritional restriction on bovine skeletal muscle. Using a custom cDNA microarray of 9,274 probes from cattle muscle and s.c. fat libraries, we examined the differential gene expression profile of the LM from 10 Brahman steers under three different dietary treatments. The statistical approach was based on mixed-model ANOVA and model-based clustering of the BLUP solutions for the gene x diet interaction effect. From the results, we defined a transcript profile of 156 differentially expressed array elements between the weight loss and weight gain diet substrates. After sequence and annotation analyses, the 57 upregulated elements represented 29 unique genes, and the 99 downregulated elements represented 28 unique genes. Most of these co-regulated genes cluster into groups with distinct biological function related to protein turnover and cytoskeletal metabolism and contribute to our mechanistic understanding of the processes associated with remodeling of muscle tissue in response to nutritional stress.

Simultaneous liquid chromatographic determination of creatinine and pseudouridine in bovine urine and the effect of sample pH on the analysis

A rapid, reliable method for the simultaneous determination of creatinine and pseudouridine is described. Both analytes were detected at an optimum wavelength of detection (262 nm), considering the relative levels present in bovine urine. Cimetidine was used as the internal standard and detected at its maximum wavelength of absorption (220 nm) on a separate channel. All three compounds were eluted within 15 min, using a 10 mmol/L phosphate buffer (pH 6.8)-methanol gradient on a C18 column. Creatinine data were found to be significantly dependent upon the pH of the sample. Recoveries of both analytes were above 96%. Lowest detectable levels of creatinine and pseudouridine were 0.28 nmol and 9.0 pmol, respectively. The use of internal standard resulted in a method with high precision (standard deviation of 1.42 mmol/L and 0.027 mmol/L for creatinine and pseudouridine), yet one that was simple and rapid.

Simultaneous determination of creatinine and pseudouridine concentrations in bovine plasma by reversed-phase liquid chromatography with photodiode array detection

A simple, rapid method for the simultaneous determination of creatinine and pseudouridine in bovine plasma is described. Plasma was de-proteinised, concentrated, and chromatographed for 15 min on a C(18) column. Analytes were detected at an optimum wavelength (262 nm) and the internal standard (cimetidine) was detected at 220 nm. The pH of analysis was between 6.5 and 7 where both analytes exist in single chemical forms giving maximum accuracy. Recoveries of both analytes were above 96%. Lowest detectable amounts of creatinine and pseudouridine were 0.28 nmol and 9.0 pmol, and the typical levels detected (+/-SD) were 60 (+/-2.8) and 2.3 (+/-0.10) micromol/L, respectively.

Postmortem interactions of muscle temperature, pH and extension on beef quality

The effect of pH, temperature and structural damage of muscle early postmortem on the quality of beef, particularly tenderness, was examined in a randomized complete block design with a 2 x 2 x 2 factorial. Semitendinosus muscles were excised from the right sides of 64 Charolais crossbred steer carcasses, placed in a restraint device in a controlled environment and subjected to high (31 degrees C) or low (20 degrees C) temperature, high (control) or low (electrically stimulated) pH and restraint at excised length or restraint at 125% of excised length for 15 min early postmortem. Temperature, pH, shrink, drip loss, cooking loss, sarcomere length, fragmentation index, shear force, color reflectance and collagen and protein solubilities of the muscles were measured after 7 d of aging at 2 degree C. High-temperature aging increased fragmentation index and color reflectance and decreased protein solubility (P less than .05). Decreasing pH via electrical stimulation increased sarcomere length of the muscles aged at the high temperature only (P less than .05). Extension of muscles prior to aging lowered shear force values of the low-temperature muscles compared with the high-temperature muscles (6.12 vs 7.84 kg, SE .38). Stimulation of the muscles also decreased collagen solubility in the high-temperature, extended muscles. Although postmortem temperature and pH were the factors that influenced meat quality most, early postmortem extension should be considered as a modulating variable of meat tenderness.

Clinical trials with Cendehill strain attenuated rubella virus vaccine

The inhibitory and bactericidal concentrations of electrically generated silver ions were 10 to 100 times lower than for silver sulfadiazine. Effects on normal mammalian cells were minimal.