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Differentiating Sarcoplasmic Proteomes of Color-stable and Color-labile Beef Muscles
Department of Animal and Food Sciences
In the present day U.S. beef retailing, marketability of individual whole-muscle cuts is increasing. Psoas major is the beef muscle marketed as filet mignon or tenderloin, and is color-labile; whereas Longissimus lumborum, retailed as New York Strip steak, is a color-stable beef muscle. The differences in the meat color stability attributes of these two well-characterized beef muscles are, in part, due to the differences in the abundance of sarcoplasmic proteome.
Identifying the sarcoplasmic proteome components that contribute to differential color stability is necessary to develop muscle-specific antioxidant strategies and packaging technologies to improve marketability and maximize the color shelf-life of whole-muscle beef cuts.
Characterizing differential abundance of sarcoplasmic proteome in color-stable and color-labile muscles will also elucidate potential breed-based and species-based (European cattle vs. Brahman cattle) variations in beef color, and will aid in genetic selection of animals with increased levels of antioxidant proteins for improving beef color stability.
2010 Project Description
We employed two-dimensional gel electrophoresis (2-DE) to differentiate the sarcoplasmic proteomes of color-stable (Longissimus lumborum; LL) and color-labile (Psoas major; PM) beef muscles and to correlate the differential abundance of proteome with biochemical attributes governing meat color stability. LL and PM muscles were obtained from seven beef carcasses (USDA Select grade) 24 h post-mortem.
Muscles were fabricated into 2.54-cm steaks, packaged in polyvinyl chloride overwrap, and stored in refrigerated retail display for 0, 5, and 9 days. Displayed steaks were utilized for analyses of instrumental color (raw surface and internal cooked color), metmyoglobin reducing activity, total reducing activity, pH, oxygen penetration, and percentage myoglobin denaturation. Results indicated differences (P <0.05) between LL and PM for these attributes. LL and PM samples for 2-DE were collected on day 0 and frozen at -80C. Sarcoplasmic proteome was isolated, dissolved in rehydration buffer, subjected to first dimension isoelectric focusing on immobilized pH gradient strips (17 cm, pH 5-8), and separated on SDS-PAGE (12.5%) in second dimension.
Analyses of gel images revealed that fifteen protein spots are differentially abundant in LL and PM. Identification of these proteins using mass spectrometry and bioinformatic tools is currently underway.
Our preliminary investigations indicated that the sarcoplasmic proteomes of beef LL and PM muscles are different. Characterizing differential abundance of sarcoplasmic proteomes in beef color-stable and color-labile muscles will aid development of muscle-specific packaging and antioxidant strategies to prolong beef color shelf-life and decrease discoloration-induced revenue loss to the meat industry.
Suman, S.P.; Mancini, R.A.; Ramanathan, R.; Konda, M.R. 2010. Modified atmosphere packaging influences premature browning in beef Longissimus lumborum steaks. Fleischwirtschaft International, 3: 54-55.