Recipient Organization
UTAH STATE UNIVERSITY
(N/A)
LOGAN,UT 84322
Performing Department
Nutrition Dietetics & Food Sci
Non Technical Summary
In response to increasing consumer demand for high-quality meat, it is necessary to understand the factors controlling the development of meat quality attributes. Meat quality is largely influenced by the alteration in muscle nature post-harvest, where a rise in meat acidity plays a crucial role. For instance, the rate of muscle acidification is a significant factor that determines the color, texture, and juiciness of fresh meat, all of which are important to consumers. Additionally, preserving the color during retail display is another significant aspect that affects the value and appeal of fresh meat to consumers.Mitochondria (cellular organelles) are typically thought to not play a role in meat quality development because the absence of oxygen in postmortem muscle limits their function. However, new findings show that mitochondria can still considerably impact the rate and degree of muscle acidification and meat quality during storage, even though their specific role is not entirely understood. Therefore, the overall objective of the proposed research is to delineate the role of mitochondria in modulating the rate of postmortem muscle acidification and meat color stability during storage. This research will provide important insights into how mitochondria impact the process of converting muscle to meat as well as directions to improve the predictability and quality of fresh meat.
Animal Health Component
30%
Research Effort Categories
Basic
70%
Applied
30%
Developmental
(N/A)
Goals / Objectives
The overall objective of the proposed research is to delineate the role of mitochondria in modulating postmortem metabolism and meat shelf stability during storage and display. We will accomplish the overall research objective by pursuing the following specific aims: 1. Investigate the role of mitochondria in modulating the rate of postmortem metabolism and pH decline in pork; 2. Determine the contribution of mitochondria-mediated oxidative stress to beef color stability during retail display; 3. Determine metabolic differences between muscles varying in mitochondrial content, rate of pH decline, and color stability using untargeted metabolomics profiling.
Project Methods
Aim 1: Sixteen market-weight pigs will be harvested, and a sample from the longissimus muscle of each animal will be collected. The muscle samples will be pulverized under liquid nitrogen, and four subsamples will be collected from each sample in centrifuge tubes. Pulverized muscle samples will be homogenized in a reaction buffer containing 10 mM Na2HPO4, 30 mM creatine, 25 mM carnosine, 10 mM Na-acetate, 60 mM KCl, 5 mM MgCl2, 40 mM glycogen, 5 mM ATP, 0.5 mM ADP, and 0.5 mM NAD (pH 7.4). Then, one tube will receive CPI-613, the second tube will receive avidin, the third tube will receive CPI-613 + avidin, and the fourth tube will receive diluent. Aliquots will be removed at 0, 60, 120, 240, and 1440 min to determine pH, glycolytic metabolites, and enzymatic activity. The same 16 pigs will also be utilized in a separate in situexperiment. Within 5 min postmortem, the longissimusmuscle will be excised from the other side of the carcass and fabricated into ten 2.5-cm-thick steaks. Steaks will be randomly injected with one of two treatments: DS16570511 dissolved in saline solution to inhibit mitochondrial calcium uptake or saline only (control). One steak from each treatment will be used immediately (0 min), while the remaining steaks will be packaged and stored at 4 °C for 60, 120, 240, or 1440 min. At each time point, steaks will be removed from their packages, and cytosolic calcium, color, pH, drip loss, and glycolytic metabolites will be evaluated.Aim 2: Market-weight steers (n = 16) will be harvested, and the longissimusand psoas major muscles will be collected from one side of all carcasses 24 h postmortem. Each muscle will then be fabricated into eight 2.5-cm-thick steaks. Steaks will be randomly injected with either mitoTEMPO dissolved in saline or saline only (control). One steak from each treatment will be used immediately (0 h storage), and the remaining steaks will be packaged in a high-oxygen-modified atmosphere (80% O2, 20% CO2) and placed in a display case maintained at 4 °C for 24 h, 168 h, or 336 h. At the end of each display period, pH, color, myoglobin redox forms, MRA, mitochondrial efficiency, ROS level, mPTP opening, cytochrome c level, and lipid oxidation will be evaluated.Aim 3: In aim 3, two independent experiments will be conducted. In the first study, we will investigate possible differences in metabolomic profiles of porcine skeletal muscles known to vary in mitochondrial content and rates of pH decline. To achieve this goal, a sample (~20 g) will be collected from the masseter, longissimus, and semimembranosus muscles of 16 pigs within 10 min postmortem. Additional samples will also be collected from each muscle at 60, 120, 480, and 1440 min postmortem. Samples from all time points will be frozen under liquid nitrogen and stored at −80 °C. The abundance of selected glycolytic and mitochondrial proteins, pH, and untargeted metabolomic profiling will be performed at each time point. In the second study, we will examine differences in metabolomic profiles of 3 different bovine muscles known to vary in mitochondrial content and color stability. Psoas major, longissimus, and semimembranosuswill be excised from 16 steers within 30 min postmortem. Each muscle will be fabricated into four 2.5-cm-thick steaks. One steak from each muscle will be used immediately, and the remaining steaks will be packaged in a high-oxygen-modified atmosphere and stored at 4 °C for 1, 7, or 14 d. At the end of each storage period, each steak will be cut into two portions; one portion will be used for meat quality measurements, while the other will be snap-frozen in liquid nitrogen and stored at −80 °C for protein abundance and metabolomics analyses.