Mechanisms of water-holding capacity of meat: The role of postmortem biochemical and structural changes

Pre-slaughter, slaughter and post-slaughter practices of slaughterhouse workers in Southeast, Nigeria: Animal welfare, meat quality, food safety and public health implications

BACKGROUND

Pre-slaughter stress or the welfare condition of food-producing animals (FPAs) and the slaughter practices of slaughterhouse workers (SHWs) are critically important for the safety and quality of meats processed in slaughterhouses (SHs). Consequently, this study determined the pre-slaughter, slaughter, and post-slaughter (PSP) practices of SHWsin four SHs in Southeast, Nigeria; and discussed the impacts on meat quality and safety.

METHODS

The PSP practices were determined by observation method. Additionally, a structured and validated closed-ended questionnaire was used to determine the knowledge of the SHWs on: the effects of poor welfare (preslaughter stress) on the quality and safety of meats produced, carcass/meat processing practices and modes of transmission of meat-borne zoonotic pathogens during carcass/meat processing. Finally, a systematic post-mortem inspection (PMI) was conducted on cattle, pigs and goats slaughtered, and economic losses accruable from condemned carcasses/meats were estimated.

RESULTS

Food-producing animals were transported to the SHs or held in the lairage under inhumane conditions. A pig being conveyed to one of the SHs was seen gasping for air, as it was firmly tied on motorbike at the thoracic and abdominal regions. Fatigued cattle were forcefully dragged on the ground from the lairage to the killing floor. Cattle for slaughter were restrained, held in lateral recumbency and left groaning, due to extreme discomfort, for about one hour before slaughter. Stunning was not performed. Singed pig carcasses were dragged on the ground to the washing point. Although more than 50% of the respondents knew the modes of transmission of meat-borne zoonotic pathogens during meat processing, 71.3% of the SHWs processed carcasses on bare floor, 52.2% used same bowl of water to wash multiple carcasses while 72% did not wear personal protective equipment during meat/carcass processing. Processed meats were transported to meat shops in an unsanitary conditions, using open vans and tricycles. During the PMI, diseased carcasses/meats/organs were detected in 5.7% (83/1452), 2.1% (21/1006) and 0.8% (7/924) of the cattle, pig and goat carcasses inspected, respectively. Gross lesions pathognomonic of bovine tuberculosis, contagious bovine pleuro-pneumonia, fascioliasis and porcine cysticercosis were detected. Consequently, 391,089.2 kg of diseased meat/organs valued at 978 million Naira (235, 030 USD) were condemned. There were significant associations (p < 0.05) between educational level and the use of personal protective equipment (PPE) during slaughterhouse operations and knowledge that FPAs can harbour zoonotic pathogens (p = < 0.001) transmissible during carcass processing. Similarly, significant association was observed between working experience and use of PPE; and between geographical location of the respondents and knowledge that zoonotic pathogens in animals are transmissible during carcass processing or via the food chain.

CONCLUSION

The findings show that slaughter practices of SHWs have detrimental impacts on the quality and safety of meats processed for human consumption in Southeast, Nigeria. These findings underscore the need to: improve the welfare condition of slaughter-animals, mechanise abattoir operations, train and retrain the SHWs on hygienic carcass/meat processing practices. There is a need to adopt strict enforcement of food safety laws to promote meat quality, food safety and consequently promote the health of the public.

Effects of kojic acid on changes in the microstructure and myofibrillar protein of duck meat during superchilled storage

This study investigated the effect of 0.8% (m/v) kojic acid treatment on changes in the microstructure and myofibrillar protein of duck meat covered with oxygen-permeable polyvinylchloride (PVC) film (9 ± 0.5 µM) during superchilled storage (-1.65 ± 0.5°C). The superchilled samples exhibited wider gaps between muscle fibers at 5 weeks storage compared with kojic acid-treated groups. Based on the variation of water status, the water-holding capacity decreased significantly (p < 0.05), and bound water and immobilized water were gradually converted into free water during superchilled storage. For kojic acid-treated samples, however, no major changes were observed with respect to muscle structure, water status, and protein degradation at 6 weeks. The 0.8% (m/v) kojic acid treatment increased the water-holding capacity, reduced carbonyl content and protein degradation, and decreased the α-helix contents loss of myofibrillar proteins. Kojic acid treatment effectively protected myofibrillar protein structure from being destroyed during superchilled storage, suggesting that this method was a good way to reduce protein oxidation and prolonged its shelf life.

Effects of dietary disodium fumarate supplementation on muscle quality, chemical composition, oxidative stress and lipid metabolism of Hu sheep induced by high concentrate diet

Long-term feeding of high-concentrate (HC) diet causes the decrease of rumen pH, and induces subacute rumen acidosis (SARA), which results in metabolic disorders in sheep. This not only reduces animal performance, but also increases the risk of oxidative stress and inflammatory reaction. Disodium fumarate can improve the rumen buffering capacity and increase rumen pH. This experiment was conducted to investigate the effects of high concentrate diet on muscle quality, chemical composition, oxidative damage and lipid metabolism of Hu sheep, and the regulating effect of disodium fumarate. The results showed that HC diet induced SARA by reducing rumen pH value, thus causing oxidative stress and lipid metabolism disorder in longissimus lumborum (LL) muscle of Hu sheep, which also reduced meat quality by increasing shear force, drip loss, cooking loss, chewiness and hardness, and reducing the contents of crude fat and crude protein in LL muscle. However, disodium fumarate can improve meat quality of SARA Hu sheep by regulating rumen pH, inhibiting muscle oxidative stress and promoting lipid metabolism.

Characteristics of pork emulsion gel manufactured with hot-boned pork and winter mushroom powder without phosphate

This study investigated the physicochemical characteristics of pork emulsion gels manufactured from hot-boned (HB) pork and winter mushroom powder in the absence of phosphate. It was found that compared to cold-boned (CB) pork, HB pork had a higher pH and exhibited a higher myofibrillar protein solubility with a lower actomyosin content (P < 0.05). Four types of pork gels were prepared, namely CB pork without phosphate, CB pork with phosphate (CBP), HB pork without phosphate, and HB pork with winter mushroom powder but without phosphate (HBW). The total exuded fluid was comparable for the CBP and HBW gels on all storage days. In addition, the HB and HBW gels had similar springiness and cohesiveness properties to the CBP gel (P > 0.05). These results indicate that the quality of pork gels manufactured in the absence of phosphate can be improved by the use of HB pork and with the incorporation of winter mushroom powder.

In-situ Indirect Measurements of Real-Time Moisture Contents During Microwave Vacuum Drying of Beef and Carrot Slices Using Terahertz Time-Domain Spectroscopy

Moisture content (MC) is a critical quality indicator for food drying processing, however achieving in-situ non-destructive analyses of dynamic MC of products during processing is still a challenge. This study developed an in-situ indirect measurement method using Terahertz time-domain spectroscopy (THz-TDS) for real-time MC prediction of foods during microwave vacuum drying (MVD). During MVD, THz-TDS continuously sense the dynamic moisture vapour from the desiccator through a polyethene air hose. The obtained THz spectra were processed to calibrate MC loss prediction models using support vector regression, Gaussian process regression and ensemble regression. Then the MC was calculated using moisture loss prediction results. The best real-time MC prediction results for beef and carrot slices achieved R² of 0.995, RMSE of 0.0162, and RDP of 22. The developed system provides a novel method for drying kinetics research during MVD and expands the applicability of the THz-TDS technique in the food industry.

Effects of dietary supplementation with different levels of palygorskite-based composite on growth performance, antioxidant capacity, and meat quality of broiler chickens

This study was conducted to investigate the effects of different levels of palygorskite-based composite (PBC) on growth performance, antioxidant status, and meat quality of broilers. A total of 320 one-day-old mixed-sex Ross 308 broiler chicks were allocated to 1 of 5 groups with 8 replicates of 8 birds each, and given a basal diet supplemented with 0, 250, 500, 1,000, and 2,000 mg/kg PBC for a 42-day trial, respectively. PBC quadratically increased feed efficiency during the late and overall experimental periods (P < 0.05). Compared with the control group, 1,000 mg/kg PBC increased feed efficiency during the overall period (P < 0.05). PBC linearly increased serum total superoxide dismutase (T-SOD) activity at 21 d and glutathione peroxidase (GSH-Px) activity at both 21 d and 42 d (P < 0.05). Compared with the control group, PBC supplementation, regardless of its level, increased 21-day serum SOD activity (P < 0.05). The 21-day serum GSH-Px activity was increased by PBC when its level exceeded 250 mg/kg (P < 0.05). PBC linearly increased 42-day total antioxidant capacity (T-AOC) activity, but linearly decreased 42-day malondialdehyde level in liver (P < 0.05). An addition of PBC, irrespective of its level, increased 42-day hepatic T-AOC activity (P < 0.05). PBC quadratically increased 45-min yellowness value and linearly increased 24-h pH value, but quadratically decreased 24-h lightness value and linearly and quadratically reduced 24-h drip loss in breast muscle (P < 0.05). Compared with the control group, the 24-h drip loss of breast muscle was decreased by PBC, regardless of its dosage (P < 0.05). An addition of PBC linearly increased 42-day T-AOC and T-SOD activities of breast muscle (P < 0.05). Compared with the control group, muscle T-SOD activity was increased by PBC, regardless of its administration level (P < 0.05). These results suggested that PBC could improve growth performance, antioxidant capacity, and meat quality of broilers, and its recommended dosage is 1,000 mg/kg.

Effects of supplementing sweet sorghum with grapeseeds on carcass parameters, and meat quality, amino acid, and fatty acid composition of lambs

OBJECTIVE

Sweet sorghum is an important forage crop for ruminants, especially in low rainfall areas. Grapeseeds are an abundant by-product of wine-making and contain bioactive substances that can improve the antioxidant capacity of meat. We examined the effect of sweet sorghum forage with supplementary grapeseeds on carcass and meat quality in lambs.

METHODS

Twenty-eight Small-tailed Han lambs (body weight = 19.1±1.20 kg), aged 3 to 4 months, were penned, and fed individually. The lambs were divided into four groups (n = 7 each) and were offered one of four diets: i) sweet sorghum silage; ii) sweet sorghum silage + grapeseeds; iii) sweet sorghum hay; and iv) sweet sorghum hay + grapeseeds. The grapeseeds were added to the concentrate at 6% DM and the diets were fed for 100 d.

RESULTS

Sweet sorghum silage tended (p = 0.068) to increase hot carcass weight, while grapeseeds tended (p = 0.081) to decrease dressing percentage without affecting other carcass parameters. Lambs consuming supplementary grapeseeds increased (p<0.05) meat redness and tended to decrease (p = 0.075) concentration of methionine in meat. Lambs consuming sweet sorghum silage increased (p<0.001) water content of the meat and had a lower (p<0.05) concentration of n-6 polyunsaturated fatty acids (PUFA) and n-6:n-3 PUFA ratio than lambs consuming sweet sorghum hay. Saturated fatty acids content in meat was lowest (p<0.05) in lambs consuming sweet sorghum silage with grapeseeds. Lambs with supplementary grapeseeds tended (p<0.10) to increase eicosapentaenoic acid and docosahexaenoic acid and have a lower thrombogenic index than lambs not consuming grapeseeds.

CONCLUSION

It was concluded that sweet sorghum with supplementary grapeseeds fed to lambs; i) improved the color of the meat to be more appetizing to the consumer; ii) tended to improve the fatty acids composition of the meat; and iii) lowered thrombogenic index of the meat.

A Comparative Study on the Meat Quality, Taste and Aroma Related Compounds between Korean Hanwoo and Chikso Cattle

The aim of this study was to compare the meat quality and taste-and-aroma-related components of beef between breeds. For this purpose, Hanwoo and Chikso steers (n = 7 per breed) raised under identical conditions until 30 months old were used. After 24 h of slaughter, longissimus lumborum (LL) and semimembranosus (SM) muscles were collected and analyzed for technological quality, free amino acids, metabolites, and volatile compounds. The Chikso meat showed lower values for shear force and color traits (lightness, redness, and yellowness) compared to Hanwoo (p < 0.05). The Chikso presented a higher amount of sweetness-related free amino acids (alanine, proline, and threonine) in the LL muscle, while Hanwoo had a higher amount of methionine and glutamine associated with umami taste (p < 0.05). A total of 36 metabolites were identified and quantified in the meat samples; out of them, 7 compounds were affected by breed (p < 0.05). Regarding aroma compounds, a significantly higher amount of fat-derived aldehydes associated with fatty and sweet notes was found in Hanwoo, whereas a higher amount of pyrazines associated with roasty notes was found in Chikso (p < 0.05). Thus, under identical feeding conditions, breed showed a significant effect on the quality and taste-and-aroma-related components that may influence the eating quality of beef between the two breeds studied.

Biological function of resveratrol and its application in animal production: a review

With the prohibition of antibiotics in feed, plant functional substances have been widely studied as feed additives. Resveratrol, a natural stilbene, and a non-flavonoid polyphenol found in plants, possesses antioxidant, anti-inflammatory, and metabolic regulatory features. Resveratrol generated intense scientific and public interest, primarily due to its widely reported ability to prevent cancer, delay aging and alleviate related metabolic diseases. Recently, resveratrol has been studied and applied as a feed additive in animal production. This review focuses on the outline of the absorption and metabolism and biological functions of resveratrol and summarizes the application of dietary resveratrol in animal production up to the present, including pigs, poultry, and ruminants. In pigs, dietary resveratrol improved intestinal health, mitochondrial function, meat quality, and more. In poultry, studies have shown that dietary resveratrol improves growth performance and meat and egg quality and alleviates heat stress induced adverse effects. There are few studies on dietary resveratrol in ruminants; however previous studies have indicated that dietary resveratrol increases nutrient digestibility and reduces methane emissions in sheep. It is hoped that this review could provide a specific theoretical basis and research ideas for the research and application of resveratrol.

Genome-wide association study reveals genetic loci and candidate genes for meat quality traits in a four-way crossbred pig population

Meat quality traits (MQTs) have gained more attention from breeders due to their increasing economic value in the commercial pig industry. In this genome-wide association study (GWAS), 223 four-way intercross pigs were genotyped using the specific-locus amplified fragment sequencing (SLAF-seq) and phenotyped for PH at 45 min post mortem (PH45), meat color score (MC), marbling score (MA), water loss rate (WL), drip loss (DL) in the longissimus muscle, and cooking loss (CL) in the psoas major muscle. A total of 227, 921 filtered single nucleotide polymorphisms (SNPs) evenly distributed across the entire genome were detected to perform GWAS. A total of 64 SNPs were identified for six meat quality traits using the mixed linear model (MLM), of which 24 SNPs were located in previously reported QTL regions. The phenotypic variation explained (PVE) by the significant SNPs was from 2.43% to 16.32%. The genomic heritability estimates based on SNP for six meat-quality traits were low to moderate (0.07-0.47) being the lowest for CL and the highest for DL. A total of 30 genes located within 10 kb upstream or downstream of these significant SNPs were found. Furthermore, several candidate genes for MQTs were detected, including pH45 (GRM8), MC (ANKRD6), MA (MACROD2 and ABCG1), WL (TMEM50A), CL (PIP4K2A) and DL (CDYL2, CHL1, ABCA4, ZAG and SLC1A2). This study provided substantial new evidence for several candidate genes to participate in different pork quality traits. The identification of these SNPs and candidate genes provided a basis for molecular marker-assisted breeding and improvement of pork quality traits.

Cellular antioxidant mechanism of mannan-oligosaccharides involving in enhancing flesh quality in grass carp (Ctenopharyngodon idella)

BACKGROUND

Deterioration of flesh quality has bad effects on consumer satisfaction. Therefore, effects of safe mannan-oligosaccharides (MOS) on flesh quality of grass carp (Ctenopharyngodon idella) muscle were studied. A total of 540 healthy fish (215.85 ± 0.30 g) were randomly divided into six groups and fed six separate diets with graded levels of MOS (0, 200, 400, 600, 800 and 1000 mg kg^-1 ) for 60 days. This study aimed at investigating the benefits of dietary MOS on flesh quality (fatty acids, amino acids and physicochemical properties) and the protection mechanism regarding antioxidant status.

RESULTS

Optimal MOS could improve tenderness (27.4%), pH (5.5%) while decreasing cooking loss (16.6%) to enhance flesh quality. Meanwhile, optimal MOS improved flavor inosine 5'-monophosphate (IMP) of 11.8%, sweetness and umami-associated amino acid, healthy unsaturated fatty acid (UFA) of 14.9% and n-3 polyunsaturated fatty acids (n-3 PUFAs) especially C20:5n-3 (15.8%) and C22:6n-3 (38.3%). Furthermore, the mechanism that MOS affected pH, tenderness and cooking loss could be partly explained by the reduced lactate, cathepsin and oxidation, respectively. The enhanced flesh quality was also associated with enhanced antioxidant ability concerning improving antioxidant enzymes activities and the corresponding transcriptional levels, which were regulated through NF-E2-related factor 2 (Nrf2) and target of rapamycin (TOR) signaling. Based on pH_24h , cooking loss, shear force and DHA (docosahexaenoic acid, C22:6n-3), optimal MOS levels for grass carp were estimated to be 442.75, 539.53, 594.73 and 539.53 mg kg^-1 , respectively.

CONCLUSION

Dietary MOS is a promising alternative strategy to improve flesh quality of fish muscle. © 2022 Society of Chemical Industry.

Investigation of changes in proteomes of beef exudate and meat quality attributes during wet-aging

This study was performed to evaluate the effects of wet-aging (3, 7, 14, 21, and 28 d at 2 °C) on beef (longissimus lumborum muscles) exudate proteome and meat quality changes. The pH, purge loss, and tenderness of beef increased with aging (P < 0.05), while color and lipid oxidative stabilities decreased, especially when long-term (14 and 21 d) aged meat were repackaged and displayed under retail condition (P < 0.05). Nineteen proteins changed significantly with aging (FDR < 0.05), in which most of them progressively accumulated in exudates over aging periods. Combined with partial least squares discriminant analysis, 16 proteins (including 9 structural proteins, 3 metabolic enzymes, 1 heat shock protein, 2 binding proteins, and KBTBD10 protein) were screened as characteristic proteins that could be used for potential meat quality indication. These findings offered novel insight into the utilization of exudates for meat quality assessment.

Reactive oxygen species-mediated oxidative stress accelerates glycolysis via activation of the CaMKKβ/AMPK pathway in the yak longissimus dorsi postmortem

BACKGROUND

Adenosine monophosphate-activated protein kinase (AMPK) is instrumental in the initiation of early postmortem glycolysis and the advent of pale, soft, and exudative (PSE) meat when cellular energy is altered. However, conflicting studies show that AMPK activation without corresponding energy level changes in PSE meat challenges this long-held notion. Here, we examined the effects of reactive oxygen species (ROS)-mediated oxidative stress on AMPK activation in the context of glycolysis, protein solubility, and water-holding capacity (WHC) in the postmortem yak longissimus dorsi (LD) muscle. Further, we explored the mechanisms underlying these effects.

RESULTS

Hydrogen peroxide (H₂ O₂ ) significantly augmented the degree of oxidative stress, increasing the production of ROS and malondialdehyde excessive production and reducing the activity of the anti-oxidants superoxide dismutase and glutathione peroxidase. In turn, oxidative stress dramatically promoted AMPK activation and glycolysis by increasing glycogen depletion and promoting hexokinase and phosphofructokinase activity. Subsequently, lactic acid accumulation increased, leading to a rapid decline in pH, which aggravated protein solubility degree and centrifugal loss in the early postmortem yak LD muscle. Importantly, these changes caused by oxidative stress were eliminated by the AMPK inhibitor. Mechanistically, oxidative stress elevated calcium ion (Ca²⁺ ) levels, which mobilized calcium/calmodulin-dependent protein kinase β (CaMKKβ) and AMPK. Rescue experiments confirmed that the increases were attenuated using Ca²⁺ and CaMKKβ chelators, respectively.

CONCLUSION

These results indicated that oxidative stress caused by ROS hastened early-stage postmortem glycolysis and reduced the WHC of yak meat. These effects were likely mediated by the alternative and energy-independent CaMKKβ/AMPK signaling pathway. © 2022 Society of Chemical Industry.

Effect of hazelnut skin by-product supplementation in lambs' diets: Implications on plasma and muscle proteomes and first insights on the underlying mechanisms

This study aimed to evaluate the effect of hazelnut skin by-product supplementation on lamb meat quality characteristics and plasma and muscle proteomes. Twenty-two Valle del Belice male lambs were divided into two experimental groups: control (C), fed a maize-barley diet and hazelnut (H), fed hazelnut skin by-product as maize partial replacer in the concentrate diet. The meat of lambs fed hazelnut skin showed greater values of lightness, redness, yellowness, and chroma color parameters together with the highest myofibril fragmentation index. Two-dimensional electrophoresis and mass spectrometry applied on plasma proteome identified 20 protein spots corresponding to 18 unique gene names to be differently expressed due to hazelnut skin by-product substitution. For the early post-mortem muscle, 23 protein spots (42 unique gene names) were significantly up-regulated due to hazelnut skin by-product supplementation. Four proteins these being APOA1, PHB, ACTG1 and ALB, were found to be common to the two proteomes suggesting that these proteins could be candidate biomarkers to monitor in vita and post-mortem lamb meat quality traits. This study evidenced the main mechanisms involved in the supplementation of hazelnut skin by-product in lambs' diet and confirmed the possibility of using plasma proteome as a non-invasive way to predict lamb meat quality. SIGNIFICANCE: Maximizing the use of agro-industrial by-products as replacers of traditional feedstuff for improving animal products is one of the important challenges to preserving natural resources and guaranteeing environmental sustainability. Hazelnut (Corylus avellana L.) skin, obtained as a results of hazelnut roasting, represents a valuable by-products due to its high content in unsaturated fatty acids, tannins, and vitamins. Thus, including hazelnut skin by-product in small ruminant nutrition could reduce the costs of animal feedings for farmers as well as improve meat nutritional and sensorial characteristics. Additionally, monitoring the meat quality characteristics with fast, accurate, and non-invasive tools to find, before slaughter, animals with desired quality characteristics is of growing interest in the last years. In this regard, the objectives of this study were to assess i) the effect of hazelnut skin supplementation on lamb meat quality characteristics and plasma and muscle proteomes, and ii) whether analyzing plasma proteome by using a gel-based proteomic approach could effectively offer a more readily available option for determining lamb meat quality. Taken together, the proteomic approach applied to plasma and muscle proteomes, allowed us to reveal the pathways and the potential candidate plasma biomarkers to predict lamb meat production in the pre-slaughter phase.

A Mixture of Full-Fat and Defatted Hermetia illucens Larvae and Poultry By-Products as Sustainable Protein Sources Improved Fillet Quality Traits in Farmed Barramundi, Lates calcarifer

The physicochemical quality and shelf-life of fillets from barramundi, which were fed for 56 days on a mixture of poultry by-product meal (PBM), full-fat Hermetia illucens (FHI), and defatted HI (DHI), were investigated and compared to a fishmeal (FM) control diet. The proximate and total amino acids compositions of the fillets were unaffected by the test diets, while the mixture of PBM and HI larvae improved the sensory quality. An eight-day shelf-life study showed that PBM-HI-based diets improved the texture profile based upon the chewiness, cohesiveness, gumminess, and hardness, regardless of the storage time. The improved texture was aligned with comparatively less degradation of the microstructure of the muscle tissue in the same diets. An improvement in the quality index (QI) value, an increase in pH, and a decrease in lipid oxidation were also found in the fillets of barramundi fed test diets compared with the control diet during the storage time. The test diets positively influenced flesh lightness and redness, while the color profiles were negatively influenced by the storage time. Overall, the maintenance of compositional attributes; the enhancement of fillet sensory attributes, texture, and brightness; and the improved raw fillet shelf-life support the inclusion of PBM-HI-based diets in aquafeed.

The study of the nutritional and biological value of functional semi-finished fish products "fish balls"

In the context of the problem of the organization of high-quality nutrition for consumers, the ways of its solution by expanding the range of products based on raw fish materials are considered. The necessity of creating combined semi-finished products with adequate substitution for plant components is justified, which allows increasing the amount of dietary fiber consumed and reducing the caloric content of the product, enriching minced fish with carbohydrates (polysaccharides and dietary fibers), amino acids, as well as macro- and microelements. Thus, a comparative analysis of the content of essential amino acids in the muscle tissue of fish in the inland waters of the Republic of Kazakhstan with some oceanic and marine fish showed that the content of amino acids such as leucine, lysine, threonine, phenylalanine is slightly higher. They are characterized by a high content of essential amino acids limiting the biological value, g/100 g of protein: lysine – 8.8-11.6; methionine – 2.1-3.1; tryptophan – 1.0-1.1. The data analysis shows that a higher pH value of fish meat corresponds to a higher elasticity value. The pH shift to the alkaline side of more than 7.5, although it promotes the release of myosin, reduces the elasticity of meat. In our study, we used minced fish from Carp, Pikeperch, Bream, and Pike. It was found that with the addition of 30% of the functional supplement of kelp, the moisture-retaining capacity of the fish semi-finished product was 48.6% and pH 6.67. With the addition of 30% of the functional pumpkin additive, the moisture-retaining capacity of the fish semi-finished product was 49.27% and pH 6.04. Developing semi-finished fish products with plant components makes it possible to obtain products of high biological value with a juicy consistency, which meets modern trends in healthy nutrition.

Epigenome-wide association studies of meat traits in Chinese Yorkshire pigs highlights several DNA methylation loci and genes

In this study, we aimed to identified CpG sites at which DNA methylation levels are associated with meat quality traits in 140 Yorkshire pigs, including pH at 45 min (pH_45min), pH at 24 h (pH_24h), drip loss (DL), meat redness value (a*), yellowness (b*) and lightness (L*). Genome-wide methylation levels were measured in muscular tissue using reduced representation bisulfite sequencing (RRBS). Associations between DNA methylation levels and meat quality traits were examined using linear mixed-effect models that were adjusted for gender, year, month and body weight. A Bonferroni-corrected p-value lower than 7.79 × 10 - 8 was considered statistically significant threshold. Eight CpG sites were associated with DL, including CpG sites annotated to RBM4 gene (cpg301054, cpg301055, cpg301058, cpg301059, cpg301066, cpg301072 and cpg301073) and NCAM1 gene (cpg1802985). Two CpG sites were associated with b*, including RNFT1 and MED13 (cpg2272837) and TRIM37 gene (cpg2270611). Five CpG sites were associated with L*, including GSDMA and LRRC3C gene (cpg2252750) and ENSSSCG00000043539 and IRX1 gene (cpg2820178, cpg2820179, cpg2820181 and cpg2820182). No significant associations were observed with pH_45min, pH_24h or a*. We reported associations of meat quality traits with DNA methylation and identified some candidate genes associated with these traits, such as NCAM1, MED13 and TRIM37 gene. These results provide new insight into the epigenetic molecular mechanisms of meat quality traits in pigs.

Utilization of Electrical Conductivity to Improve Prediction Accuracy of Cooking Loss of Pork Loin

This study investigated the predictability of cooking loss of pork loin through relatively easy and quick measurable quality properties. The pH, color, moisture, protein content, and cooking loss of 100 pork loins were measured. The explanatory variables included in all linear regression models with an adjust-r² value of ≥0.5 were pH and the protein content. In the linear regression model predicting cooking loss, the highest adjust-r² value was 0.7, with pH, CIE L*, CIE b*, moisture, and protein content as the explanatory variables. In 30 pork loins, electrical conductivity was additionally measured, and as a result of linear regression analysis for predicting cooking loss, the highest adjust-r² value was 0.646 with electrical conductivity measured at 40 Hz, with pH and color as the explanatory variables. Ordinal logistic regression analysis was performed to predict the three grades (low, middle, and high) of loin cooking loss using pH, color, and 40 Hz electrical conductivity as the explanatory variables, and the percent concordance was 93.8%. In conclusion, the addition of electrical conductivity as an explanatory variable did not increase the prediction accuracy of the linear regression model for predicting cooking loss; however, it was demonstrated that it is possible to predict and classify the cooking loss grade of pork loin through quality properties that can be measured quickly and easily.

Beyond standard PSE testing: An exploratory study of bioimpedance as a marker for ham defects

During post-mortem conversion from muscle to meat, diverse quality anomalies can emerge. Recent pork defects are often accompanied by deteriorating fibre structure. Here we investigate how bioimpedance response, an indicator of structural disintegration, can help in detecting quality defects. We, first, measured the relationship between standard meat quality variables (pHu, CIELAB, drip loss) and bioimpedance (BI) response. To screen for defect-biomarkers that are linked to aberrant bioimpedance and physicochemical indicators of quality decline, we performed LC-MS/MS proteomic analysis on samples, classified with a multivariate-based separation into good versus poor quality. We found that BI correlated significantly with, e.g., colour and drip loss. Proteomics revealed eleven proteins to be unique for either, good or poor ham quality groups, and maybe linked to structural degradation. In all, our data supports a wider integration of BI testing in pork quality testing to assess structural disintegration, which can render ham unsuitable for, e.g., costly curing.

Effects of flavourzyme addition on protein degradation and flavor formation in grass carp during fermentation

This study aimed to investigate the effects of flavourzyme addition on protein degradation and flavor formation in grass carp during fermentation. The related results showed that the addition of flavourzyme reduced the moisture content and accelerated the hydrolysis of protein and generation of water-soluble flavor substances (e.g., TCA-soluble peptides, α-amino nitrogen, and free amino acids), thereby contributing to fermented grass carp products with a better taste quality. Besides, radar map results of electronic tongue and electronic nose showed that flavourzyme addition gives fermented products a more intense umami taste and odor. Meanwhile, sensory evaluation results also further confirmed that the addition of flavourzyme significantly improved the sensory attributes of fermented grass carp products, especially the taste and odor attributes. Overall, flavourzyme addition may be an effective way to shorten fermentation time and improve the flavor quality of fermented grass carp products during fermentation. PRACTICAL APPLICATIONS: In this study, to study the effects of flavourzyme addition on protein degradation and flavor formation in grass carp during fermentation, the related indicators include the moisture content, total nitrogen, non-protein nitrogen, protein degradation index, TCA-soluble peptides, α-amino nitrogen, free amino acids, electronic tongue, electronic nose, and sensory attributes were analyzed. This study may provide some useful information for the improvement of fermentation methods and the production of high-quality fermented grass carp products.

Physical properties during a 28-day ageing period of blesbok (Damaliscus pygargus phillipsi) Longissimus thoracis et lumborum and Biceps femoris muscles

The study aimed to determine the effect of sex, muscle-type, and ageing on the physical properties of blesbok (Damaliscus pygargus phillipsi) Longissimus thoracis et lumborum (LTL) and Biceps femoris (BF) muscles. Randomly assigned steak samples from twenty mature blesbok (10 of each sex) antelope were vacuum-packed and stored at 4.4 ± 1 °C for 2, 4, 7, 10, 17 and 28 ageing days. Cumulative purge loss, pH, colour (L*, a*, b), cooking loss, and Warner Braztler shear force were determined. Males had meat with higher (P = 0.032) pH values than females, while all other attributes were similar (P > 0.05). The LTL had greater (P < 0.05) purge losses, L* and a* values than the BF muscle, while other quality attributes were greater (P < 0.05) for the BF muscle. Despite fluctuations, there was an overall decrease in shear force with ageing time. According to all quality parameters measured, the optimum ageing period for blesbok would seem to be 10 days.

Profile of Nitrogenous compounds and Bacterial proliferation in Rabbit meat stored cold with three types of packaging

Meat is an excellent medium for bacterial growth due to its high water and nutrient content. The nitrogenous compounds (NC) are derived through decarboxylation of amino acids due to microbial enzymes. The objective of this study was to evaluate the concentration of 3 NC and the proliferation of some microorganisms in rabbit meat with three treatments (T) , classified by three types of packaging for 21 days (d) in rabbit meat stored cold. The meat samples were obtained of the Longissimus thoracis et lumborum muscle. Each sample was divided and two groups were formed. The first group was used to measure the physicochemical characteristics of the meat, and the second group was used to quantify NC and bacterial isolation. The pH in the meat decreased from 0 to 21 d in the three T. The brightness (L*) decreased (P<0.05), while the variables a* and b* increased (P<0.05) to 21 d for all groups. Histamine and cadaverine remained low and were similar in the three T (P>0.05). Putrescine (PU) increased (P<0.05) from 7 to 21 d in the Control-Plastic (CP) and Semi-permeable plastic film (SP) groups vs. Vacuum packing (VP). The Enterobacteriaceae remained constant throughout the experimental period in the three T, compared to the aerobic mesophilic, which was higher (P<0.05) until 21 d of the evaluation in CP and SP. The type of packaging and cooling time influenced the concentration of NC. The VP had the lowest level of PU and mesophilic bacteria until 21 d of storage.

Research progress on quality deterioration mechanism and control technology of frozen muscle foods

Freezing can prolong the shelf life of muscle foods and is widely used in their preservation. However, inevitable quality deterioration can occur during freezing, frozen storage, and thawing. This review explores the eating quality deterioration characteristics (color, water holding capacity, tenderness, and flavor) and mechanisms (irregular ice crystals, oxidation, and hydrolysis of lipids and proteins) of frozen muscle foods. It also summarizes and classifies the novel physical-field-assisted-freezing technologies (high-pressure, ultrasound, and electromagnetic) and bioactive antifreeze (ice nucleation proteins, antifreeze proteins, natural deep eutectic solvents, carbohydrate, polyphenol, phosphate, and protein hydrolysates), regulating the dynamic process from water to ice. Moreover, some novel thermal and nonthermal thawing technologies to resolve the loss of water and nutrients caused by traditional thawing methods were also reviewed. We concluded that the physical damage caused by ice crystals was the primary reason for the deterioration in eating quality, and these novel techniques promoted the eating quality of frozen muscle foods under proper conditions, including appropriate parameters (power, time, and intermittent mode mentioned in ultrasound-assisted techniques; pressure involved in high-pressure-assisted techniques; and field strength involved in electromagnetic-assisted techniques) and the amounts of bioactive antifreeze. To obtain better quality frozen muscle foods, more efficient technologies and substances must be developed. The synergy of novel freezing/thawing technology may be more effective than individual applications. This knowledge may help improve the eating quality of frozen muscle foods.

The Effects of Preslaughter Electrical Stunning on Serum Cortisol and Meat Quality Parameters of a Slow-Growing Chinese Chicken Breed

Electrical stunning is widely utilized prior to a neck cut to induce unconsciousness in order to improve animal welfare and slaughter efficiency in the broiler production industry. However, slaughter without stunning is still very commonly used in China, in part because there is a belief that stunning reduces meat quality. The purpose of this study was to determine whether the physical (hemorrhages, pH, drip loss, and shear force) and chemical (inosinic monophosphate concentration and reducing sugar content) properties of broiler meat differed between chickens in preslaughter stunning and nonstunned slaughter groups, and whether the groups differed in their levels of cortisol as an indicator of stress. Serum cortisol levels of the nonstunned group were nearly twice as high as those in the stunned group (p < 0.05). Several meat quality indicators were better in the stunned group than in the nonstunned group. We concluded that electrical stunning prior to slaughter significantly decreases the stress caused by slaughter, resulting in both improved animal welfare and meat quality traits.

Quality and Processability of Modern Poultry Meat

The poultry meat industry has gone through many changes. It moved from growing dual-purpose birds (meat and egg production) taking ~110 days to reach 1.2 kg 100 years ago, to developing specialized meat breeds that grow to 2.5 kg within ~40 days. It also moved from selling ~80% whole birds to mostly selling cut up and further processed products in the Western world. This necessitated building large, centralized processing plants, capable of processing 15,000 birds per hr on a single line (60 years ago only 2500), that require higher bird uniformity (size, color, texture). Furthermore, consumer demand for convenient products resulted in introducing many cut-up fresh poultry (some companies have 500 SKU) and further processed products (chicken nuggets did not exist 50 years ago). Those developments were possible due to advancements in genetics, nutrition, medicine, and engineering at the farm and processing plant levels. Challenges keep on coming and today a rise in myopathies (e.g., so called woody breast, white striping, spaghetti meat), requires solutions from breeders, farmers, and processing plants, as more automation also requires more uniformity. This review focuses on the changes and challenges to the processing industry segment required to keep supplying high quality poultry to the individual consumer.

Characterization of Pork Loin Chop Color Stability Using Loin Quality Traits and Instrumental Discoloration Measures

The objective of this study was to characterize the color stability of pork loin chops using fresh quality traits and instrumental measures of discoloration. Boneless pork loins (N=484) were evaluated for quality traits at 11 or 14 d post-mortem. One chop was cut from each loin near the 10th rib for retail display, overwrapped, and displayed under constant fluorescent lighting for 7 d. Objective color, myoglobin redox forms, and subjective visual discoloration traits were evaluated daily. After retail display, chops were categorized based on final visual discoloration (Day 7) as Very Color Stable (VCS; 0% to 5% discoloration), Color Stable (CS; 5% to 10% discoloration), Neutral (10% to 25% discoloration), Color Labile (CL; 25% to 30% discoloration), or Very Color Labile (VCL; &gt;30% discoloration). Quality and color traits were analyzed using the GLIMMIX (visual discoloration) or MIXED (all other measures) procedure of SAS. Retail display data were analyzed as repeated measures. Chops ultimately classified as CS or VCS were darker, redder, and had lesser surface metmyoglobin (P&lt;0.01) than CL and VCL chops at both Day 1 of retail display and throughout display. Stable chops also had generally increased R630/580 values as well as decreased visual discoloration scores and yellowness during display. A group×day interaction was observed for all traits measured during retail display (P&lt;0.0001). No differences in aged loin ventral surface redness were observed between color stability groups (P≥0.16). Overall, chops ultimately classified as CS came from aged loins that were generally darker, redder, and less yellow, with greater pH values, greater marbling scores,and decreased purge loss.

Effect of Lactobacillus plantarum and flavourzyme on physicochemical and safety properties of grass carp during fermentation

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Fermentation decreased pH and Aw and increased ANN, TBARS, TVB-N, and BAs in grass carp flesh.

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Fermentation with Lactobacillus plantarum and flavourzyme could improve physicochemical properties of fermented grass carp.

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Fermentation of Lactobacillus plantarum and flavourzyme could contribute to fermented grass carp with safety properties.

The present study aimed to investigate the change in physicochemical and safety properties of grass carp during fermentation with flavourzyme and Lactobacillus plantarum (FLF). The natural fermentation (NF) and fermentation with Lactobacillus plantarum (LF) samples were used as control. The results showed that with increasing fermentation time, the pH and water activity (Aw) in each fermented grass carp sample gradually decreased, while the a-amino nitrogen (ANN), thiobarbituric acid reactive substance (TBARS), total volatile base nitrogen (TVB-N), biogenic amines (BAs), and harmful microbial gradually increased. Besides, compared with NF samples at each fermentation time, significantly lower pH, Aw, TBARS, TVB-N, BAs, and harmful microbial presented in LF and FLF samples. However, FLF samples have a higher AAN content than that of NF and LF samples during fermentation. Overall, the fermentation with Lactobacillus plantarum and flavourzyme could contribute to fermented grass carp products with better physicochemical and safety properties.

Application of gamma radiation in the beef texture development during accelerated aging

This study aimed to evaluate the effects of gamma radiation (3 kGy) on the quality of post-rigor beef (M. longissimus lumborum) aged for up to 21 days at different temperatures (1, 7, and 15°C). Irradiation reduced the mesophilic and lactic acid bacteria counts, which were higher in the non-irradiated samples aged at 7 and 15°C. The water retention capacity was lower in the irradiated beef, resulting in higher values of exudation and cooking losses. High aging temperatures increased the exudation loss and myofibrillar proteolysis (lower fragmentation index; FI) and reduced the total and insoluble collagen contents and the beef Warner-Bratzler square Shear Force (WBsSF). However, irradiated beef had higher FI and SF than non-irradiated ones, increasing the time required for the beef tenderizing. Gamma irradiation (3 kGy) can be used to ensure the microbiological safety during short storage at high temperatures (up to 15°C) in order to accelerate the process of beef tenderizing.

Effects of alfalfa levels on carcass traits, meat quality, fatty acid composition, amino acid profile, and gut microflora composition of Heigai pigs

Recent years have witnessed a dramatic increase in the demand for healthy and high-quality pork. Alfalfa, one of the most popular perennial forages, is considered a rich source of highly nutritional forage for livestock feed, as it contains over 90% insoluble dietary fiber. Nevertheless, there is a paucity of data confirming the effects of adding alfalfa on pork quality, amino acid composition, and intestinal microbiota composition. Therefore, the objective of this study was to investigate the effects of different dietary levels of alfalfa on carcass traits, meat quality, amino acid and fatty acid composition, and the intestinal microbiota of Heigai pigs. A total of 72 finishing Heigai pigs were randomly assigned to two groups (n = 36), with six replicate groups and six pigs per replication. The two experimental diets were formulated to include graded levels of alfalfa, 20% (AM20) and 30% (AM30). The results showed that adding 30% alfalfa meal did not affect the growth performance of Heigai pigs but significantly reduced backfat thickness (P < 0.05), pH (P < 0.05), increased the a^* value, b^* value, and flavor amino acid and essential amino acid contents in longissimus dorsi muscle (LDM). In addition, AM30 didn't affect colonic microbiota abundance but significantly reduced the relative abundances of three phyla, such as Verrucomicrobia, and 43 genera, such as Akkermansia, and significantly increased the relative abundances of 47 genera, such as Prevotella-2. Overall, these results advocate for a diet containing 30% alfalfa to improve meat quality by changing the intestinal microflora composition without affecting the growth performance of Heigai pigs, which provides compelling evidence for the use of alfalfa to relieve the pressure on corn and soybean meal demand and produce high-quality pork.

Inclusion of Grape Pomace in Finishing Cattle Diets: Carcass Traits, Meat Quality and Fatty Acid Composition

Because of its high content of polyphenolic compounds, dietary inclusion of grape pomace (GP) in finishing cattle diet could possibly enhance product quality and the health value of beef lipids. Therefore, the aim of this study was to evaluate the effects of feeding a high amount of grape pomace in finishing cattle diets on carcass traits, product quality, and fatty acid (FA) composition of beef. Jersey × Holstein crosses (n = 24) were fed either a typical finishing diet (CON) or a finishing diet containing 58% grape pomace (DM basis; HGP). Following the feeding period, animals were harvested, and carcass traits measured. Longissimus lumborum (LL) and semimembranosus (SM) muscle were then collected from each carcass for sensory quality evaluation and FA profile analysis. Hot carcass weight, backfat thickness, and preliminary and final yield grades were greater (p ≤ 0.04) for CON than HGP steers. However, there was no diet effect on rib eye area (REA), kidney, pelvic, and heart (KPH) fat, and marbling. Feeding the HGP compared to CON diet reduced lipid oxidation of LL and SM steaks over time; the malondialdehyde (MDA) concentration, which did not differ on d 0 and 2 of 8-d simulated retail display, was lower on d 4, 6 and 8 for HGP than CON steers (treatment × day of simulated display interaction; p < 0.01). Brightness (L* values) and redness (b*) were greater for LL steaks from HGP than CON steers on most days of simulated display (treatment × day of simulated display interaction; p < 0.01). In addition, the LL and SM muscle content of several FA linked to positive health outcomes in humans including 18:2 n-6, 18:2 c9t11, total conjugated linoleic acid (CLA) and total polyunsaturated fatty acid (PUFA) was also greater (p ≤ 0.02) for steers fed the HGP compared to the CON diet. In summary, current findings suggest that although it could possibly limit growth performance, feeding a high amount of grape pomace to finishing cattle could enhance both the sensory quality and the health value of beef lipids, which are key in increasing consumer acceptability of beef.

Vacuum Packaging Maintains Fresh Characteristics of Previously Frozen Beef Steaks during Simulated Retail Display

The impact of frozen storage on beef steaks prior to the retail setting may result in changes to the quality and safety of the packaged meat. Therefore, the objective of the current study was to evaluate fresh characteristics on previously frozen steaks during a simulated retail display. Steaks were allocated to one of three packaging treatments (MB, MDF, MFS) and stored frozen (−13 °C) for 25 days in the absence of light. After thawing, steaks were stored in a lighted retail case at 3 °C and evaluated for instrumental surface color, pH, purge loss, lipid oxidation, and microbial spoilage organisms throughout the 25-day fresh display period. There was an increase (p < 0.05) for aerobic plate counts and lipid oxidation from day 20 through 25 on steaks packaged in MFS and MDF, respectively. Steaks packaged in MB were redder (p < 0.05) and more vivid (C*) as storage time increased. Whereas lipid oxidation was greater (p < 0.05) throughout the entire display for steaks packaged in MFS and MDF. It is evident that barrier properties of MB limiting oxygen exposure of the steak preserved fresh meat characteristics after frozen storage. Results from the current study suggest that vacuum packaging films can aid in retarding detrimental effects caused by frozen storage after placing the steaks in fresh retail conditions.

Physicochemical Characteristics and Flavor-Related Compounds of Fresh and Frozen-Thawed Thigh Meats from Chickens

The physicochemical characteristics and flavor-related compounds of thigh meat derived from diverse Korean native chickens (KNC), namely Hanhyup No. 3 (HH3), Woorimatdag No 1 (WRMD 1), and Woorimatdag No 2 (WRMD 2), under fresh and frozen-thawed conditions were studied and compared with those of commercial broilers (CB). Regardless of the breed, KNC showed a higher (p < 0.05) percentage of linoleic and arachidonic acid. The highest proportion of docosahexaenoic acid was observed in WRMD 2. Despite having a higher collagen content, thigh meat derived from KNC maintained a similar texture profile in comparison to that of CB. The concentrations of most free amino acids (FAA), except for taurine, tryptophan, and carnosine, were higher in frozen-thawed meat than in fresh meat. Regarding volatile organic compounds (VOC), following freezing, the concentration of favorable VOCs increased in CB, but decreased in WRMD 1, suggesting a loss of pleasant flavor in frozen-thawed meat. This study indicated that changes in VOCs, including hydrocarbons (d-limonene, heptadecane, hexadecane, naphthalene, pentadecane, 3-methyl-, tridecane), esters (arsenous acid, tris(trimethylsilyl) ester, decanoic acid, ethyl ester, hexadecanoic acid, ethyl ester), alcohol (1-hexanol, 2-ethyl-), ketones (5,9-undecadien-2-one, 6,10-dimethyl-), and aldehydes (pentadecanal-, tetradecanal, tridecanal), may be a promising marker for distinguishing between fresh and frozen-thawed chicken thigh meat. These findings are of critical importance as preliminary data for developing high-quality chicken meat products.

Effect of ageing and MAP on quality of striploin from cattle of Holstein-Friesian breed

There have been determined the features of m. longissimus lumborum steaks from young cattle-for-fattening of Holstein-Friesian breed, Polish black-and-white variety. There were measured pH values, basic chemical composition and colour parameters. The meat was subjected to moist-ageing for 12 days and, next, stored in modified atmosphere for the following 10 days. The amount of heat loss in relation to the temperature of thermal processing was determined. Texture parameters were studied instrumentally and organoleptically. The studied muscles from young cattle-for-fattening characterised with proper and similar pH values. The average fat content was 4.37%. The surface colour of the studied dorsal muscle was relatively bright, the average value L*=37.97, and on the cross-section L*=32.97. The average value of the muscle surface's ‘redness’ was a*=18.98, whereas cross-section's a*=20.27. The amounts of heat leakages were rising along with the increase of temperature from 11.24 to 37.14%. Ageing and storing in MAP led to a significant decrease in the amounts of heat leakages. Ageing and storing in MAP had a significant influence on decreasing shear force and on increasing the organoleptic evaluation marks of the m. longissimus lumborum after thermal processing, which shows that the muscle may become culinary meat with features accepted by consumers.