Search research reports:
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.
2011 Project Description
Muscles in beef carcasses are categorized based on color stability. Psoas major (PM) is a color-labile beef muscle, whereas Longissimus lumborum (LL) is color-stable. Sarcoplasmic proteome is comprised of soluble proteins and constitutes approximately one-third of total skeletal muscle proteins.
Meat color stability is influenced by the biomolecular interactions between myoglobin and sarcoplasmic proteins. However, the differential abundance of sarcoplasmic proteome in beef muscles and its role in muscle-specific color stability have not been explored thoroughly. Therefore, we attempted to differentiate the sarcoplasmic proteomes of color-labile (PM) and color-stable (LL) beef muscles and to correlate the differential abundance of proteome with color attributes.
PM and LL muscles were obtained from seven (n=7) beef carcasses (USDA Select grade, 24 h post-mortem) and were fabricated into 2.54-cm steaks. Individual steaks were aerobically packaged and stored under refrigerated retail display for 0, 5, and 9 days. Samples for proteome analysis were collected on day 0. At the end of storage periods, instrumental color and biochemical traits influencing color were evaluated. LL steaks exhibited greater (P <0.05) surface redness (a* value), color stability (ratio of reflectance at 630 nm and at 580 nm), and metmyoglobin reducing activity than their PM counterparts.
Sarcoplasmic proteome was analyzed employing two-dimensional electrophoresis, tandem mass spectrometry, and bioinformatic tools. Sixteen differentially abundant proteins were identified, and the identified proteins included chaperones and antioxidant proteins. Sarcoplasmic proteins demonstrating a positive correlation with redness (aldose reductase, creatine kinase, pyruvate dehydrogenase, and beta-enolase), color stability (peroxiredoxin-2, peptide methionine sulfoxide reductase, pyruvate dehydrogenase, stress-induced phosphoprotein, and heat shock protein-27 kDa), and metmyoglobin reducing activity (peptide methionine sulfoxide reductase) were over-abundant in LL.
The over-abundance of antioxidant proteins and chaperones can inhibit myoglobin oxidation and protein aggregation, respectively, and thus contributes to the improved color stability of LL steaks.
At the point-of-sale, consumers often consider cherry-red color of fresh meat as a reliable indicator of wholesomeness. Discolored meats are sold at discounted price, and the estimated annual revenue loss for the United States farm economy corresponding to meat discoloration is $1 billion.
The modern day beef industry has increasingly been retailing individual whole-muscle cuts. Of the several intrinsic factors governing color stability, muscle source received significant attention with the achievement of beef muscle profiling. Individual muscles have specific anatomical locations, physiological functions, and cellular metabolism. Consequently, each beef muscle demonstrates unique post-mortem biochemistry and color stability. Moreover, the effects of different processing strategies on beef color are muscle-dependant.
The findings of the present study indicated that the sarcoplasmic proteome components contribute to differential color stability in beef whole-muscle steaks and that the abundance of several antioxidant proteins is muscle-dependant. These results insinuated the necessity to engineer muscle-specific processing strategies (antioxidant, enhancement, and packaging technologies) to maximize the color shelf-life and improve marketability of beef whole-muscle cuts.
Suman, S.P.; Joseph, P.; Li, S.; McClelland, K.M.; Rentfrow, G.; Beach, C.M. Proteome basis of muscle-specific beef color stability. In proceedings of 57th International Congress of Meat Science and Technology, August 2011, Ghent, Belgium. Paper # 003.
Joseph, P.; Rentfrow, G.; Slaughter, L.L.; McClelland, K.M.; Suman, S.P.; Boling, J.A.; Brennan, K.M.; Matthews, J.C. Effect of dietary selenium supplementation on color shelf-life of beef Psoas major steaks from maturing heifers. American Meat Science Association Annual Reciprocal Meat Conference, June 2011, Manhattan, KS. Abstract # 24.
Joseph, P.; Suman, S.P.; Rentfrow, G.; Li, S.; Beach, C.M. (2012). Proteomics of muscle-specific beef color stability. Journal of Agricultural and Food Chemistry (Accepted).