Pork Water-holding Capacity Research Articles

Study on the effects of pre-slaughter transport stress on water holding capacity of pork: Insights from oxidation, structure, function, and degradation properties of protein

This work systematically investigated the effects of pre-slaughter transport stress on pork water holding capacity (WHC) during aging from the perspectives of oxidation, structure, function, and degradation properties of protein. Pigs were randomly divided into three-hour transport (Transport-induced stress, T group) and three-hour transport followed by three-hour resting (Control, TR group). Results demonstrated that T treatment markedly declined pork WHC. Compared with TR group, T group presented increased oxidation levels. Meanwhile, T treatment exacerbated the shift of protein secondary structure from α-helix to random coil and protein unfolding levels. The decreased solubility, thermal stability, and degraded levels of proteins were also observed in T group. Additionally, muscle contractions of T group were more severe than TR group. This study supported that pre-slaughter transport stress altered physicochemical properties and structures of postmortem muscle proteins, which reduced pork WHC via impairing the interactions between protein and water molecules and changing the muscle fiber structure.

UBXN1 is a strong candidate gene in regulation of pork water-holding capacity.

The UBX domain containing protein 1-like gene (UBXN1) promotes the degradation of myofibrillar proteins during meat maturation, which affects meat water-holding capacity (WHC). This study aims to identify functional mutations in UBXN1 promoter region, which affects the transcription activity and therefore the WHC. Firstly, we confirmed that the UBXN1 expression level was positively associated with WHC. Individuals with high and low WHC ( per group) were selected from 168 Duroc Large White Yorkshire (D L Y) crossbred pigs. The UBXN1 promoter region was comparatively sequenced using DNA pools from these two groups, and a mutation ca. 379T G was revealed that had reverse allele distribution. The single nucleotide polymorphism (SNP) was then genotyped in the abovementioned population. TT genotype individuals exhibited higher UBXN1 mRNA level and higher WHC compared with GG genotype ones. Further luciferase assay confirmed that TT genotype promoter had higher activity. Moreover, the degradation of cytoskeletal framework proteins of muscle cells like desmin, synemin, dystrophin, and vinculin was higher in TT genotype individuals than GG ones. In conclusion, we identified a SNP in the UBXN1 gene promoter that contributes to WHC improvement and pork quality. And UBXN1 is a strong candidate gene in regulation of pork WHC.

Contribution of calpain to protein degradation, variation in myowater properties and the water-holding capacity of pork during postmortem ageing

To investigate calpain’s effect on protein degradation, myowater properties, and the water-holding capacity (WHC), porcine longissimus muscles were incubated with control buffer, PD150,606 (calpain-specific inhibitor) and MG-262 (multiple-protease inhibitor) and assigned to an ageing period of 1, 4 or 7 d. Over 7 d of storage, no significant differences (P > 0.05) were observed in desmin or integrin expression between the MG-262 and PD150,606 groups, which indicated that calpain played a major role in protein proteolysis. Compared to those in the control group, muscle samples subjected to PD150,606 and MG-262 exhibited higher water mobility and a poorer WHC. Additionally, there were no significant differences in myowater properties or the WHC between the two groups at 1 d postmortem (P > 0.05). Calpain regulated the distribution and mobility of myowater, which contributed to a higher WHC in the early postmortem period (before 4 d), but other proteases tended to take over at a later stage.

192 Transcriptome Analysis for Pork Color – the Ham Halo Effect in Biceps Femoris.

Pork color is a major indicator of product quality that guides consumer purchasing decisions. For hams, consumers prefer a uniform pink color. Recently, industry has received an increase in consumer complaints about the lightness and non-uniformity of ham color, primarily lighter color in the periphery termed “ham halo” that is not caused by manufacturing procedures. This effect is seen in fresh and processed hams and the outer, lighter muscle is associated with lower myoglobin concentrations, pH and type I fibers. The objective of this study was to identify differences in gene expression profiles between light and normal colored biceps femoris muscle from pork hams. RNA was extracted from light and normal colored biceps femoris muscle from samples from the same animal showing an extreme ham halo effect, and over 50 million paired-end reads (2x75bp) per library were sequenced on an Illumina NextSeq 500. Seventy-six to 82% of trimmed high quality reads were mapped to the Sscrofa 10.2 assembly and unplaced scaffolds. Differentially expressed genes (DEGs) were identified using DESeq2 and GFOLD. DESeq2 identifies DEGs between groups and GFOLD identifies DEGs in samples from an individual animal. A total of 14,809 transcripts were expressed in biceps femoris; 14,766 were expressed in both light and normal muscle. DESeq2 identified 340 DEGs with 318 genes being more highly expressed in normal colored muscle. Within each animal, GFOLD identified an average of 768 DEGs. GFOLD identified 50 DEGs identified in at least 8 of the 10 animals, all of which were more highly expressed in normal colored muscle. Gene ontology (GO) enrichment analysis of these genes identified transition between fast and slow fibers, and skeletal muscle adaptation and contraction as the most significant biological process terms. Of the 340 DEGs, 319 mapped to 275 unique chromosomal regions; there were 33 clusters of 2 or more genes within 200 kb of a neighboring gene or long non-coding RNA, suggesting co-transcription of DEGs. Sixty-one DEGs resided within 200 kb of 93 unique QTL or SNP associations for color traits, pH, driploss, cookloss, purge, water-holding capacity or fiber type. The evaluation of gene expression by RNA-Seq identified DEGs between regions of the biceps femoris with the ham halo effect that may be candidate genes that contribute to the variation in color, pH and water-holding capacity of pork. USDA is an equal opportunity provider and employer.

Relationship Between Protein Denaturation and Water Holding Capacity of Pork During Postmortem Ageing

This study investigated water holding capacity (WHC), water distribution, and protein denaturation of pork loin chops (longissimus lumborum) packaged in polyethylene bags throughout display at 4 ± 1 °C for up to 1, 3, 5, 7 and 9 days. The drip loss of pork eventually increased following a decrease during the first 5 days of storage. Nuclear magnetic resonance (NMR) analysis revealed an increase in population of immobilized water P22 from day 1 to day 5, meanwhile a sharp decrease after 9 days was noticed. However, an opposite trend was observed for the population of free water P23. Correlation analysis indicated that myofibrillar protein solubility was negatively correlated with drip loss (p 0.05). Furthermore, the content of α-helices increased during the first 5 days of storage (p < 0.05), which suggested increased WHC during the earlier period of postmortem storage. During the subsequent postmortem storage, the content of α-helices decreased significantly (p < 0.05), while the β-sheets and β-turns increased. The maximum temperatures (Tmax) of three endothermic peaks were found to be 53.6 °C, 65.2 °C, and 77.6 °C at 1 day postmortem. A significant decrease were observed for Tmax peakI,Tmax peakII,Tmax peakIII at 9 d when compared to 1 d postmortem (p < 0.05), suggesting loss of thermal stability and protein denaturation.

Effects of High Oxygen Packaging on Tenderness and Water Holding Capacity of Pork Through Protein Oxidation

The objective of this study was to investigate the biochemical difference of pork under high oxygen modified atmosphere packaging and their contribution to meat tenderness and water holding capacity of pork during postmortem storage. Twelve longissimus dorsi muscles were randomly assigned to either high oxygen modified atmosphere packaging or vacuum packaging and stored for 1, 4, and 6 days at 4 °C. The carbonyl content, protein surface hydrophobicity, protein solubility, calpain activity, desmin degradation, tenderness, and water loss of pork were determined. Results showed that carbonyl content, protein surface hydrophobicity, and protein solubility were significantly affected (P 0.05). Samples from high oxygen modified atmosphere packaging at 1 day showed greater intensity of intact 80 KDa calpain and lower intensity of autolyzed 76 KDa calpain product compared to samples from vacuum packaging (P 0.05). Higher intensity of intact desmin was observed in samples from high oxygen modified atmosphere packaging than vacuum packaging samples from 1 day of postmortem storage. Both packaging method and storage time showed significant effects (P < 0.05) on tenderness and water loss of pork muscle during postmortem storage. Changes in protein oxidation, calpain activation, and protein proteolysis of postmortem pork under high oxygen modified atmosphere packaging could help to explain decreased meat tenderness and increased centrifuge loss of pork.

A splice mutation in the PHKG1 gene causes high glycogen content and low meat quality in pig skeletal muscle.

Glycolytic potential (GP) in skeletal muscle is economically important in the pig industry because of its effect on pork processing yield. We have previously mapped a major quantitative trait loci (QTL) for GP on chromosome 3 in a White Duroc × Erhualian F2 intercross. We herein performed a systems genetic analysis to identify the causal variant underlying the phenotype QTL (pQTL). We first conducted genome-wide association analyses in the F2 intercross and an F19 Sutai pig population. The QTL was then refined to an 180-kb interval based on the 2-LOD drop method. We then performed expression QTL (eQTL) mapping using muscle transcriptome data from 497 F2 animals. Within the QTL interval, only one gene (PHKG1) has a cis-eQTL that was colocolizated with pQTL peaked at the same SNP. The PHKG1 gene encodes a catalytic subunit of the phosphorylase kinase (PhK), which functions in the cascade activation of glycogen breakdown. Deep sequencing of PHKG1 revealed a point mutation (C>A) in a splice acceptor site of intron 9, resulting in a 32-bp deletion in the open reading frame and generating a premature stop codon. The aberrant transcript induces nonsense-mediated decay, leading to lower protein level and weaker enzymatic activity in affected animals. The mutation causes an increase of 43% in GP and a decrease of>20% in water-holding capacity of pork. These effects were consistent across the F2 and Sutai populations, as well as Duroc × (Landrace × Yorkshire) hybrid pigs. The unfavorable allele exists predominantly in Duroc-derived pigs. The findings provide new insights into understanding risk factors affecting glucose metabolism, and would greatly contribute to the genetic improvement of meat quality in Duroc related pigs.

UBE3B and ZRANB1 polymorphisms and transcript abundance are associated with water holding capacity of porcine M. longissimus dorsi

The degradation of myofibrillar proteins during meat maturation affects the water holding capacity (WHC) of meat. Our study sought to identify polymorphisms in UBE3B and ZRANB1, genes encoding proteins involved in ubiquitination, and to evaluate the relationship between genotype, transcript abundance, and WHC of pork. A single SNP of ZRANB1, c.552A>G (p.Ile153Val), and two silent SNPs of UBE3B, c.1921A>T and c.4292C>T, were associated with muscle pH, conductivity, meat colour, or drip loss in German Landrace (GL, n=266) and Pietrain×(Large White×German Landrace) (PiF1, n=316). Further, carriers of the minor alleles at the SNPs tended to have increased transcript abundance. Consistent with the protein degradation promoting and inhibiting effects of UBE3B and ZRANB1, respectively, and the expected impact on WHC, their expressions were positively and negatively associated with WHC. The results implicate that the SNPs in both genes are in linkage with a causal site that affects transcript abundance and WHC.

Phospholipase A 2 and antioxidant enzyme activities in normal and PSE pork

In order to reveal the relationship between phospholipase A 2 and antioxidant enzymes and drip loss in pork, the study was designed to examine the effects of phospholipase A 2 and antioxidant enzymes on the water-holding capacity of pork during postmortem chilling. Six PSE and RFN samples (longissimus muscle) were used to determine the activities of phospholipase A 2 (tPLA 2, cPLA 2 + sPLA 2 and iPLA 2), superoxide dismutase (SOD) and GSH-Px, and acid phospholipase. The results showed that pH 1 h and pH 24 h from PSE pork were lower ( p < 0.01) than for normal pork (RFN), but the L* value at 1 h and 24 h postmortem, TBARS content, drip loss at 48 h and 96 h, cooking loss, tPLA 2 activity and iPLA 2 were higher ( p < 0.01) than of normal pork. Correlation analysis indicated that drip loss at 48 h was negatively related to pH 1 h ( p < 0.01) and pH 24 h ( p < 0.01) but positively to T 1 h ( p < 0.01) and the activities of total phospholipase A 2 ( p < 0.05) and calcium-independent phospholipases A 2 ( p < 0.01). The tPLA 2 and GSH-Px play important roles in drip loss.

Effects of conventional freezing processing and frozen storage on pork water-holding capacity and structure

Effects of conventional freezing processing and frozen storage on pork water-holding capacity and structure

Effects of nutritional modifications on the water‐holding capacity of fresh pork: a review

Although genetics and preslaughter handling and management have the greatest impact on pork quality - especially water-holding capacity (WHC) - modifications to swine diets may offset the negative effects of genotype and/or pig handling on pork quality or improve quality attributes of pork from pigs with the genetic potential for good quality. There is little evidence that pork WHC is altered by the lysine or protein level (and source), cereal grain, or fat source used in growing-finishing diets. Yet, recent research indicates that feeding low-starch, high-fibre, high-fat, glycogen-reducing diets effectively improves the WHC of pork. Moreover, meta-analysis of the available information indicated that including 100, 200, or 400+ mg of alpha-tochopherol per kilogram of diet reduced pork drip losses by 10.1%, 30.5%, and 25.9%, respectively, whereas supplementing swine diets with magnesium for 1-2 days, 3-4 days, or 5-7 days reduced drip losses by 23.1%, 13.7%, or 15.9%, respectively. Some swine nutritionists have advocated the removal of vitamins and trace minerals from finishing diets; however, deletion of vitamin/trace mineral premixes actually reduced the WHC of pork, whereas drip losses were reduced by elevating the dietary inclusion levels of vitamins and trace minerals 150-250% of the recommended levels. Additionally, there is no evidence that feeding pigs ractopamine hydrochloride or injections of porcine somatotropin affect pork WHC. There may not be a single 'silver bullet' that will remedy poor quality genetics or poor animal management, but improvements in pork WHC can be achieved with some modifications to swine finishing diets.

The effect of ageing on the water-holding capacity of pork: role of cytoskeletal proteins

The water-holding capacity (WHC) of pork decreases post-mortem but has been shown to increase during subsequent ageing. In order to test a hypothesis that water-holding capacity increases during ageing due to degradation of the cytoskeleton, WHC was followed 10 days post-mortem and related to the extent of proteolysis of cytoskeletal proteins. A fast method for measuring WHC in small meat samples was developed by the use of centrifugation. The WHC of fresh pork decreases in the first part of post-mortem storage after which it increases to the level of 1 day PM. No changes in total water content of the meat were observed which could explain changes in WHC during ageing. Vinculin and desmin degrade gradually during ageing while talin degrades rapidly. These observations are consistent with the hypothesis that degradation of the cytoskeleton slowly removes the linkage between lateral shrinkage of myofibrils and shrinkage of entire muscle fibres, so removing the force that causes flow into the extracellular space. Inflow of previously expelled water is then possible, so increasing WHC as observed in later periods of storage.