Date Full Report Received09/30/2020
Date Abstract Report Received09/30/2020
Funded ByNational Pork Board
The production of high-quality pork is essential to the food and agriculture industries’ success and sustainability. Tenderness of fresh pork is among the most critical attributes determining consumer satisfaction of fresh pork and, therefore, the product’s value. Consumers assign value based on experienced quality, which is primarily influenced by tenderness. In the retail, food service, and export markets, a significant variation in pork tenderness is experienced, and this variation detracts from the product value. Continued and sustained market presence requires a consistent product quality. Therefore, defining the quality before delivery is necessary for initial and ongoing market access. Controlling and predicting fresh pork quality is exceptionally challenging because, despite years of research, we still do not fully understand the biology of early postmortem muscle that governs major quality features, including tenderness and water-holding capacity. The only way the research community and the food industry can develop reliable pork quality indicators is to understand factors that determine quality.
Pork tenderness improves through the degradation of myofibrillar proteins in postmortem muscle. Postmortem proteolysis of myofibrillar proteins is well documented during meat aging, primarily by the calpain family of proteases. Degradation of myofibrillar proteins can occur at variable rates and occasionally to a minimal degree, resulting in less tender meat. One source of proteolysis variation can be the rate and extent of tissue and protein oxidation. Peroxiredoxins are a family of antioxidant proteins ubiquitously expressed in cells. Their function is to reduce reactive oxygen species (ROS), primarily hydrogen peroxide. We hypothesized that variation in these antioxidant proteins could vary across pigs and phenotypes and, therefore, explain variation in pork quality. Specifically, we asked how abundance and state of peroxiredoxin-2 and peroxiredoxin-6 are linked to fresh pork loin tenderness differences.
The results demonstrate that peroxiredoxin-2 is involved in postmortem changes, specifically proteolysis, linked to pork’s tenderness. The decrease in abundance of peroxiredoxin-2 shows that it is degraded or altered in some way during aging. Less abundant PRXD-2 in aged pork was observed in more tender pork with more significant desmin degradation. Importantly, abundance and oxidation of peroxiredoxin-2 are linked to swine growth performance with a greater aboundnce and oxidation linked to less efficient growth and less tender pork. A new observation that can help us understand the nature of the metabolism is that the oxidation states of PRXD-2 change during aging. This question has never been investigated, and the results show that some forms of PRXD-2 are more resilient during aging, which could explain less proteolysis. The next question is to define the molecular nature of the novel band 3 of non-reduced PRXD- to determine its role in proteolysis and definition of fresh pork tenderness.
• Greater abundance of the antioxidant protein Peroxiredoxin-2 in aged pork loin indicates less proteolysis and less tender pork.
• The abundance of Peroxiredoxin-2 changes at a variable rate during aging based on tenderness classification.
• There is a transition in oxidation state of Peroxiredoxin -2 during postmortem aging.
• Abundance of Peroxiredoxin-6 did not change during postmortem aging.
• Antemortem conditions that alter Peroxiredoxin-2 status and abundance do not change overall protein oxidation in pork longissimus muscle.