Assessing the impact of ultrasound on the rate and extent of early post-mortem glycolysis in bovine Longissimus thoracis et lumborum.

The rate of pH decline, early post-mortem, has been identified as a key factor that impacts the tenderness of meat, and manipulating this rate of pH decline is highly relevant to ensure consistent high quality meat. Ultrasound is a potential intervention in early post - mortem muscle that may have an impact on the rate of glycolysis through its ability to alter enzyme activity. Following a variety of different ultrasound treatments frequencies (25 and 45 kHz) and durations (15, 30 and 45 min), it was found, when analysed in muscle, that ultrasound treatment duration, specifically the 30 min treatment, and interaction between treatment duration and frequency, had a significant impact on the rate of pH decline, post - treatment. Frequency did not have a significant effect on the rate of pH decline, post - treatment, in muscle. Ultrasound did not have a significant permanent effect on the activity of glycolytic enzymes present in bovine Longissimus lumborum et thoracis muscle, where no significant differences were observed on the rate of pH decline and rate of change of reducing sugars, glycogen and lactic acid, when analysed in an in vitro glycolytic buffer. It seems that the impact observed in intact muscle is not as a consequence of a permanent change in enzymatic activity, instead indicating an impact on conditions in the muscle which enhanced enzyme activity.

Impact of sampling location and aging on the Longissimus thoracis et lumborum muscle proteome of dry-aged beef.

This study aimed to explore the differences in the proteome and molecular pathways between two sampling locations (external, internal) of bovine Longissimus thoracis et lumborum (LTL) muscles at 0, 21, and 28 days of dry-aging (i.e. 3, 24, and 31 days post-mortem). It further assessed the impact of post-mortem aging on the meat proteome changes and the biological processes at interplay. Proteins related to defence response to bacterium and regulation of viral entry into host cell were identified to be more abundant on the external location before dry-aging, which may be associated to the oxidative conditions and microbial activity to which post-mortem muscle is exposed during dressing, chilling, and/or quartering of the carcasses. This highlights the relevance of sampling from interior tissues when searching for meat quality biomarkers. As dry-aging progressed, the meat proteome and related biological processes changed differently between sampling locations; proteins related to cell-cell adhesion and ATP metabolic processes pathways were revealed in the external location at 21 and 28 days, respectively. On the other hand, the impact of aging on the proteome of the interior meat samples, evidenced that muscle contraction and structure together with energy metabolism were the major pathways driving dry-aging. Additionally, aging impacted other pathways in the interior tissues, such as regulation of calcium import, neutrophil activation, and regeneration. Overall, the differences in the proteome allowed discriminating the three dry-aging times, regardless of the sampling location. Several proteins were proposed for validation as robust biomarkers to monitor the aging process (tenderization) of dry-aged beef: TTN, GRM4, EEF1A1, LDB3, CILP2, TNNT3, GAPDH, SERPINI1, and OMD.

Molecular mechanisms contributing to the development of beef sensory texture and flavour traits and related biomarkers: Insights from early post-mortem muscle using label-free proteomics.

Beef sensory quality comprises a suite of traits, each of which manifests its ultimate phenotype through interaction of muscle physiology with environment, both in vivo and post-mortem. Understanding variability in meat quality remains a persistent challenge, but omics studies to uncover biological connections between natural variability in proteome and phenotype could provide validation for exploratory studies and offer new insights. Multivariate analysis of proteome and meat quality data from Longissimus thoracis et lumborum muscle samples taken early post-mortem from 34 Limousin-sired bulls was conducted. Using for the first-time label-free shotgun proteomics combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS), 85 proteins were found to be related with tenderness, chewiness, stringiness and flavour sensory traits. The putative biomarkers were classified in five interconnected biological pathways; i) muscle contraction, ii) energy metabolism, iii) heat shock proteins, iv) oxidative stress, v) regulation of cellular processes and binding. Among the proteins, PHKA1 and STBD1 correlated with all four traits, as did the GO biological process 'generation of precursor metabolites and energy'. Optimal regression models explained a high level (58-71%) of phenotypic variability with proteomic data for each quality trait. The results of this study propose several regression equations and biomarkers to explain the variability of multiple beef eating quality traits. Thanks to annotation and network analyses, they further suggest protein interactions and mechanisms underpinning the physiological processes regulating these key quality traits. SIGNIFICANCE: The proteomic profiles of animals with divergent quality profiles have been compared in numerous studies; however, a wide range of phenotypic variation is required to better understand the mechanisms underpinning the complex biological pathways correlated with beef quality and protein interactions. We used multivariate regression analyses and bioinformatics to analyse shotgun proteomics data to decipher the molecular signatures involved in beef texture and flavour variations with a focus on multiple quality traits. We developed multiple regression equations to explain beef texture and flavour. Additionally, potential candidate biomarkers correlated with multiple beef quality traits are suggested, which could have utility as indicators of beef overall sensory quality. This study explained the biological process responsible for determining key quality traits such as tenderness, chewiness, stringiness, and flavour in beef, which will provide support for future beef proteomics studies.

Influence of meat sample geometry on dehydration dynamics during dry-aging of beef.

Meat geometry may impact on the dehydration kinetics during dry-aging influencing the drying rate and, potentially, aspects of meat quality. In this study, three meat geometries (slices, steaks and sections) were prepared from three bovine Longissimuss thoracis et lumborum at 3 days post-mortem and were dry-aged at 2 °C, 75% relative humidity with an airflow of 0.5-2.0 m/s for 22 days (slices), 48 days (sections) and 49 days (steaks). Weights were recorded during dry-aging and drying curves were obtained for the three geometries, with the larger sections showing limited dehydration due to internal resistance to moisture migration from the core to the surface. Seven thin-layer equations were fitted to the dehydration data in order to model the drying kinetics during dry-aging. Thin-layer models described reliably the drying kinetics of the three geometries. In general, reduced k values (h-1) reflected the lower drying rates as thickness increased. The Midilli model provided the best fit for all geometries. Proximate analyses of the three geometries and bloomed colour of sections were measured at the start and the end of the dry-aging period. Moisture loss during dry-aging led to the concentration of protein, fat and ash contents; while no significant differences were found for L*, a* and b* values of sections before and after the dry-aging process. In addition, moisture content, water activity (aw) and LF-NMR measurements were taken at different locations within beef sections to further explore water dynamics during dry-aging.

DIGE Analysis of Animal Tissues.

Two-dimensional difference gel electrophoresis (2D-DIGE) is an acrylamide gel electrophoresis-based technique for protein separation and quantification in complex mixtures. The technique addresses some of the drawbacks of conventional 2D polyacrylamide gel electrophoresis (2D-PAGE), offering improved sensitivity, more limited experimental variation, and accurate within-gel matching. 2D-DIGE is based on direct labeling of proteins with isobaric fluorescent dyes (known as CyDyes: Cy2, Cy3, and Cy5) prior to isoelectric focusing (IEF). Here, up to two samples and a reference pool (internal standard) can be mixed and loaded onto IEF for first dimension prior to SDS (sodium dodecyl sulfate)-PAGE separation in the second dimension. After the electrophoretic run, the gel is imaged at the specific excitation wavelength for each dye, in sequence, and gel scans are recorded separately. For each individual protein spot, intensities recorded at the different wavelengths are integrated and the ratio between volumes normalized to that of the internal standard. This provides an immediate appreciation of protein amount variations under the different conditions tested. In addition, proteins of interest can still be excised and identified with conventional mass spectrometric techniques and further analyzed by other biochemical methods. In this chapter, we describe application of this methodology to separation and quantitation of protein mixtures from porcine muscle exudate, collected following centrifugation of muscle specimens (centrifugal drip) for the characterization of quality parameters of importance in meat industry.

Drying dynamics of meat highlighting areas of relevance to dry-aging of beef.

Drying of foods is a processing step, which has a variety of outcomes from improving shelf life and product stability, to reducing weight, or to achieving a targeted product eating quality. Drying is key step in the manufacturing of some dried meat products, such as jerky. It is also a major event that occurs when beef is dry-aged, where beef is exposed to air under defined conditions for an extended aging period. Although the conditions typically used to produce dried meat products are significantly different from those that prevail during dry-aging, both involve a gradual removal of water from muscle. As there is a paucity of research on the kinetics of the dehydration process occurring during dry-aging of beef, this paper comprehensively reviews models used to describe drying kinetics in other beef products, in order to gain insights regarding the key factors that impact water removal from meat. Consideration is given as to how the specific conditions during dry-aging such as air flows used (approximately 2 m/s), high air relative humidity, low temperature, and meat geometry will influence the kinetics of the drying. With regard to modeling, equations derived from Fick's second law of diffusion (e.g., thin-layer models) have been used to describe the drying kinetics of small-sized meat products. However, to apply Fick's law to dry-aging, some different considerations may need to be evaluated such as: tridimensional geometry (i.e., whole muscle); uniform initial moisture content; isotropic diffusion; negligible shrinkage;and a combination of internal and external resistances.

The Influence of Bloom Index, Endotoxin Levels and Polyethylene Glycol Succinimidyl Glutarate Crosslinking on the Physicochemical and Biological Properties of Gelatin Biomaterials.

In the medical device sector, bloom index and residual endotoxins should be controlled, as they are crucial regulators of the device's physicochemical and biological properties. It is also imperative to identify a suitable crosslinking method to increase mechanical integrity, without jeopardising cellular functions of gelatin-based devices. Herein, gelatin preparations with variable bloom index and endotoxin levels were used to fabricate non-crosslinked and polyethylene glycol succinimidyl glutarate crosslinked gelatin scaffolds, the physicochemical and biological properties of which were subsequently assessed. Gelatin preparations with low bloom index resulted in hydrogels with significantly (p < 0.05) lower compression stress, elastic modulus and resistance to enzymatic degradation, and significantly higher (p < 0.05) free amine content than gelatin preparations with high bloom index. Gelatin preparations with high endotoxin levels resulted in films that induced significantly (p < 0.05) higher macrophage clusters than gelatin preparations with low endotoxin level. Our data suggest that the bloom index modulates the physicochemical properties, and the endotoxin content regulates the biological response of gelatin biomaterials. Although polyethylene glycol succinimidyl glutarate crosslinking significantly (p < 0.05) increased compression stress, elastic modulus and resistance to enzymatic degradation, and significantly (p < 0.05) decreased free amine content, at the concentration used, it did not provide sufficient structural integrity to support cell culture. Therefore, the quest for the optimal gelatin crosslinker continues.

Biodegradable Packaging Materials from Animal Processing Co-Products and Wastes: An Overview.

Biodegradable polymers are non-toxic, environmentally friendly biopolymers with considerable mechanical and barrier properties that can be degraded in industrial or home composting conditions. These biopolymers can be generated from sustainable natural sources or from the agricultural and animal processing co-products and wastes. Animals processing co-products are low value, underutilized, non-meat components that are generally generated from meat processing or slaughterhouse such as hide, blood, some offal etc. These are often converted into low-value products such as animal feed or in some cases disposed of as waste. Collagen, gelatin, keratin, myofibrillar proteins, and chitosan are the major value-added biopolymers obtained from the processing of animal's products. While these have many applications in food and pharmaceutical industries, a significant amount is underutilized and therefore hold potential for use in the generation of bioplastics. This review summarizes the research progress on the utilization of meat processing co-products to fabricate biodegradable polymers with the main focus on food industry applications. In addition, the factors affecting the application of biodegradable polymers in the packaging sector, their current industrial status, and regulations are also discussed.

Dark-cutting beef: A brief review and an integromics meta-analysis at the proteome level to decipher the underlying pathways.

Comprehensive characterization of the post-mortem muscle proteome defines a fundamental goal in meat proteomics. During the last decade, proteomics tools have been applied in the field of foodomics to help decipher factors underpinning meat quality variations and to enlighten us, through data-driven methods, on the underlying mechanisms leading to meat quality defects such as dark-cutting meat known also as dark, firm and dry (DFD) meat. In cattle, several proteomics studies have focused on the extent to which changes in the post-mortem muscle proteome relate to dark-cutting beef development. The present data-mining study firstly reviews proteomics studies which investigated dark-cutting beef, and secondly, gathers the protein biomarkers that differ between dark-cutting versus beef with normal-pH in a unique repertoire. A list of 130 proteins from eight eligible studies was curated and mined through bioinformatics for Gene Ontology annotations, molecular pathways enrichments, secretome analysis and biological pathways comparisons to normal beef color from a previous meta-analysis. The major biological pathways underpinning dark-cutting beef at the proteome level have been described and deeply discussed in this integromics study.

A Proteomic Study for the Discovery of Beef Tenderness Biomarkers and Prediction of Warner-Bratzler Shear Force Measured on Longissimus thoracis Muscles of Young Limousin-Sired Bulls.

Beef tenderness is of central importance in determining consumers' overall liking. To better understand the underlying mechanisms of tenderness and be able to predict it, this study aimed to apply a proteomics approach on the Longissimus thoracis (LT) muscle of young Limousin-sired bulls to identify candidate protein biomarkers. A total of 34 proteins showed differential abundance between the tender and tough groups. These proteins belong to biological pathways related to muscle structure, energy metabolism, heat shock proteins, response to oxidative stress, and apoptosis. Twenty-three putative protein biomarkers or their isoforms had previously been identified as beef tenderness biomarkers, while eleven were novel. Using regression analysis to predict shear force values, MYOZ3 (Myozenin 3), BIN1 (Bridging Integrator-1), and OGN (Mimecan) were the major proteins retained in the regression model, together explaining 79% of the variability. The results of this study confirmed the existing knowledge but also offered new insights enriching the previous biomarkers of tenderness proposed for Longissimus muscle.

The influence of the interaction of sous-vide cooking time and papain concentration on tenderness and technological characteristics of meat products.

The food industry has been slow in harnessing technological developments to expand opportunities and benefit the community. One such opportunity is in the application of proteolytic enzymes to the development of softer-textured meat products that require reduced mastication force, for those with impaired dentition, and reduced strength including older adults. Proteolytic enzymes haven't been fully explored for their potential in this area. Here a response surface methodology (RSM) was applied to model the interactive effects of sous-vide and papain application on texture, color, and cooking loss of meat. An innovative meat product formulation with a reduced toughness (120 min cooking sous-vide and 0.01 mg papain/100 g) was optimized and the technological performance of the formulation was validated. Bias values of the optimized model were in the range of 0.97 to 1.06, while accuracy factors for shear force values, chewiness, TPA hardness, cooking loss, color parameters ranged from 1.00 and 1.06, both of which metrics indicated the reliability of the resultant models.

Dry-aging of beef as a tool to improve meat quality. Impact of processing conditions on the technical and organoleptic meat properties.

Meat consumers are demanding products of higher and consistent quality, with a distinctive flavor and aroma, able to provide a particular sensorial experience when consuming beef. The impact of all the factors affecting the final eating quality, known as the farm to fork approach, has been extensively studied in the last decades. This includes genetic factors, production system, transport, carcass intervention, aging, packaging and cooking method, among others. Aging is, one of the most important steps in producing high quality tender beef. During this step, flavor is developed and the meat is tenderized. Dry-aging although considered a traditional method, is currently attracting attention from consumers, producers and researchers because of the characteristics of the final products in terms of flavor, aroma and texture. This chapter will describe the series of biochemical changes, which combined with the loss of water, generates a final product that is highly appreciated by niche consumers. This will include the changes that the muscle undergoes to be transformed to meat, the main factors driving the dry-aging process and how the flavor and aroma compounds are generated during this process.

Shotgun proteomics for the preliminary identification of biomarkers of beef sensory tenderness, juiciness and chewiness from plasma and muscle of young Limousin-sired bulls.

Label free shotgun proteomics was used to analyse plasma and Longissimus muscle biopsies of Limousin-sired bulls, classified as 5 high-quality and 5 low-quality meat based on sensory texture traits (tenderness, juiciness and chewiness). A total of 31 putative protein biomarkers (16 in plasma and 15 in muscle) differed significantly in abundance between the two quality groups. The proteins were associated with muscle structure, energy metabolism, heat shock proteins, oxidative stress and proteolysis related pathways. Among them, B2M, AHSG, APOA4 and HP-20 (plasma), PFKM, MYH2, PTER, GSTM1 and MYPN (muscle) were good predictors of the three texture quality traits. Further, significant correlations were identified for FETUB, SERPINA7, ASL, TREH, HP, HP-25, AZGP1, APCS and SYT15, which are novel biomarkers from plasma that warrant further evaluation. This study is a significant step forward in elucidating proteomic profiles in bovine bio-fluids and muscle tissue, which may ultimately provide opportunities to processors for early assessment of beef sensory quality.

The influence of animal species, gender and tissue on the structural, biophysical, biochemical and biological properties of collagen sponges.

Although collagen type I is extensively used in biomedicine, no study to-date has assessed how the properties of the produced scaffolds are affected as a function of species, gender and tissue from which the collagen was extracted. Herein, we extracted and characterised collagen from porcine and bovine, male and female and skin and tendon tissues and we subsequently fabricated and assessed the structural, biophysical, biochemical and biological properties of collagen sponges. All collagen preparations were of similar purity and free-amine content (p > 0.05). In general, the porcine groups yielded more collagen; had higher (p < 0.05) denaturation temperature and resistance to enzymatic degradation; and lower (p < 0.05) swelling ratio and compression stress and modulus than the bovine groups of the same gender and tissue. All collagen preparations supported growth of human dermal fibroblasts and exhibited similar biological response to human THP-1 monocytes. These results further illustrate the need for standardisation of collagen preparations for the development of reproducible collagen-based devices. Assessment of the physicochemical and biological properties of collagen sponges as a function of animal species (bovine versus porcine), gender (male versus female) and tissue (skin versus tendon).

Molecular signatures of beef tenderness: Underlying mechanisms based on integromics of protein biomarkers from multi-platform proteomics studies.

Over the last two decades, proteomics have been employed to decipher the underlying factors contributing to variation in the quality of muscle foods, including beef tenderness. One such approach is the application of high-throughput protein analytical platforms in the identification of meat quality biomarkers. To broaden our understanding about the biological mechanisms underpinning meat tenderization across a large number of studies, an integromics study was performed to review the current status of protein biomarker discovery targeting beef tenderness. This meta-analysis is the first to gather and propose a comprehensive list of 124 putative protein biomarkers derived from 28 independent proteomics-based experiments, from which 33 robust candidates were identified worthy of evaluation using targeted or untargeted data-independent acquisition proteomic methods. We further provide an overview of the interconnectedness of the main biological pathways impacting tenderness determination after multistep analyses including Gene Ontology annotations, pathway and process enrichment and literature mining, and specifically discuss the major proteins and pathways most often reported in proteomics research.

The Extent and Rate of the Appearance of the Major 110 and 30 kDa Proteolytic Fragments during Post-Mortem Aging of Beef Depend on the Glycolysing Rate of the Muscle and Aging Time: An LC-MS/MS Approach to Decipher Their Proteome and Associated Pathways.

Post-mortem (p-m) muscle undergoes a myriad of complex physical and biochemical changes prior to its conversion to meat, which are influential on proteolysis and hence tenderization. A more in-depth understanding of the mechanisms underpinning these dynamics is a key to consistently providing tender beef. Using an LC-MS/MS approach, with state-of-art mass spectrometry Q Exactive HF-X, the proteome and associated pathways contributing to the appearance of the proteolytic breakdown products appearing over 14 days p-m, at two important molecular weights (110 and 30 kDa) on 1D SDS-PAGE gels, have been investigated in beef longissimus thoracis et lumborum muscles exhibiting four rates of pH decline differentiated on the basis of time at pH 6 (fast glycolysing, <3 h; medium, 3-5 h; slow, 5-8 h; and very slow, 8+ h). Both 110 and 30 kDa bands appeared during aging and increased in intensity as a function of p-m time in a pH decline-dependent manner. The 110 kDa band appeared as early as 3 h p-m and displayed an incremental increase in all groups through to 14 days p-m. From 2 days p-m, this increase in abundance during aging was significantly (P < 0.001) influenced by the glycolytic rate: fast > or = medium > slow > very slow. The day 2 p-m appearance of the 30 kDa band was most evident for the fast glycolysing muscle with little or no evidence of appearance in slow and very slow. For days 7 and 14 p-m, the strength of appearance was dependent on glycolysing groups fast > medium > or = slow > very slow. LC-MS/MS analysis yielded a total of 22 unique proteins for the 110 kDa fragment and 13 for the 30 kDa, with 4 common proteins related to both the actin and fibrinogen complex. The Gene Ontology analysis revealed that a myriad of biological pathways are influential with many related to proteins involved primarily in muscle contraction and structure. Other pathways of interest include energy metabolism, apoptotic mitochondrial changes, calcium and ion transport, and so on. Interestingly, most of the proteins composing the fragments were so far identified as biomarkers of beef tenderness and other quality traits.

Optimising the use of proteins from rich meat co-products and non-meat alternatives: Nutritional, technological and allergenicity challenges.

An exponential growth in the global demand for high quality proteins over the next 20 years is expected, mainly due to global population growth and the increasing awareness toward protein rich foods for more nutritive diets. Coupled with this, is the pressing need for more sustainable approaches within a bio-economy mindset. Although meat production is expected to increase to address this rising demand, a better use of the currently available resources provided by the food, and specially, the meat industry is required. In this regard, despite the high-quality proteins and other nutrients found in meat co-products; they are currently underused and their valorisation needs to be revisited. Also, emerging protein sources need to be investigated to alleviate the environmental pressure coming from the meat industry. In this review, the main focus was attributed to (i) the current and forthcoming challenges for the use of meat co-products as meat replacers to produce a new range of meat derived products (with high nutritional value, improved technological properties and better consumer acceptance); (ii) their performance regarding to the non-animal origin proteins currently used as meat protein replacers; and (iii) the allergenicity of the proteins that might fall into the category of novel protein sources.

Assessment of RNAlater® as a Potential Method to Preserve Bovine Muscle Proteins Compared with Dry Ice in a Proteomic Study.

RNAlater® is regarded as a potential preservation method for proteins, while its effect on bovine muscle proteins has rarely been evaluated. Bovine muscle protein samples (n = 12) collected from three tender (Warner⁻Bratzler shear force: 30.02⁻31.74 N) and three tough (Warner⁻Bratzler shear force: 54.12⁻66.25 N) Longissimus thoracis et lumborum (LTL) samples, preserved using two different sampling preservation methods (RNAlater® and dry ice), at two post mortem time points (day 0 and day 14), were characterized using one-dimensional electrophoresis. Fourteen bands with molecular weights ranging from 15 to 250 kDa were verified, both in the dry ice and RNAlater® storage groups, at each time point, using image analysis. A shift from high to low molecular weight fragments, between day 0 and day 14, indicated proteolysis of the muscle proteins during post mortem storage. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses and database searching resulted in the identification of 10 proteins in four bands. Protein profiles of muscle preserved in RNAlater® were similar to those of muscle frozen on dry ice storage, both at day 0 and day 14. The results demonstrate that RNAlater® could be a simple and efficient way to preserve bovine muscle proteins for bovine muscle proteomic studies.

RNA-seq of muscle from pigs divergent in feed efficiency and product quality identifies differences in immune response, growth, and macronutrient and connective tissue metabolism.

BACKGROUND: Feed efficiency (FE) is an indicator of efficiency in converting energy and nutrients from feed into a tissue that is of major environmental and economic significance. The molecular mechanisms contributing to differences in FE are not fully elucidated, therefore the objective of this study was to profile the porcine Longissimus thoracis et lumborum (LTL) muscle transcriptome, examine the product quality from pigs divergent in FE and investigate the functional networks underpinning the potential relationship between product quality and FE. RESULTS: RNA-Seq (n = 16) and product quality (n = 40) analysis were carried out in the LTL of pigs differing in FE status. A total of 272 annotated genes were differentially expressed with a P < 0.01. Functional annotation revealed a number of biological events related to immune response, growth, carbohydrate & lipid metabolism and connective tissue indicating that these might be the key mechanisms governing differences in FE. Five most significant bio-functions altered in FE groups were 'haematological system development & function', 'lymphoid tissue structure & development', 'tissue morphology', 'cellular movement' and 'immune cell trafficking'. Top significant canonical pathways represented among the differentially expressed genes included 'IL-8 signalling', 'leukocyte extravasation signalling, 'sphingosine-1-phosphate signalling', 'PKCθ signalling in T lymphocytes' and 'fMLP signalling in neutrophils'. A minor impairment in the quality of meat, in relation to texture and water-holding capacity, produced by high-FE pigs was observed. High-FE pigs also had reduced intramuscular fat content and improved nutritional profile in terms of fatty acid composition. CONCLUSIONS: Ontology analysis revealed enhanced activity of adaptive immunity and phagocytes in high-FE pigs suggesting more efficient conserving of resources, which can be utilised for other important biological processes. Shifts in carbohydrate conversion into glucose in FE-divergent muscle may underpin the divergent evolution of pH profile in meat from the FE-groups. Moreover, altered amino acid metabolism and increased mobilisation & flux of calcium may influence growth in FE-divergent muscle. Furthermore, decreased degradation of fibroblasts in FE-divergent muscle could impact on collagen turnover and alter tenderness of meat, whilst enhanced lipid degradation in high-FE pigs may potentially underlie a more efficient fat metabolism in these animals.

Opportunities and perspectives for utilisation of co-products in the meat industry.

Meat co-products are the non-meat components arising from meat processing/fabrication and are generated in large quantities on a daily basis. Co-products are considered as low added-value products, and in general it is difficult for industries to divert efforts into increasing their value. While many of these products can be edible those not used for human consumption or pet food is usually processed to be used as animal feed, fertilizer or fuel. However, to a large extent meat co-products are an excellent source of high nutritive value protein, minerals and vitamins and hence may be better diverted to contribute to alleviate the increasing global demand for protein. In this review the current uses, legislation and potential techniques for meat co-products processing are reviewed with the aim of showing a route to improve meat industry sustainability, profitability and better usage of available resources.