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Y. H. KIM1, M. C. Hunt2, R. A. Mancini, Jr.2, D. H. Kropf2, and J. S. Smith3. (1) Food Science, Kansas State Univ., Gradaute Research Assistant, 216 Weber Hall, Manhattan, KS 66506, (2) Dept. of Animal Sciences and Industry, Kansas State Univ., 224 Weber Hall, Manhattan, KS 66506, (3) Food Science Institute, Kansas State Univ., 208 Call Hall, Manhattan, KS 66506 Lactate is commonly used in both raw and cooked meat products because it inhibits microbial growth, minimizes off odor and flavors, and improves juiciness and tenderness. Lactate enhancement also has been recognized as a color stabilizer of both raw and cooked meat products. However, the mechanism by which lactate enhancement improves meat color stability is not fully understood. Nicotinamide adenine dinucleotide (NADH) plays a major role in the reduction of metmyoglobin in ante- and postmortem muscle. NADH is produced by reduction of NAD through lactate dehydrogenase (LDH) in postmortem muscle. Therefore, we hypothesize that lactate's ability to minimize discoloration could be related to the replenishment of NADH via LDH activity. Our objective was to determine the influence of lactate enhancement on color stability, LDH enzyme activity, NADH contents, and metmyoglobin reducing activity (MRA) in enhanced strip loins. Twelve USDA Select strip loins were enhanced 10% with aqueous solutions containing lactate, phosphate, salt, and/or acetate. Steaks packaged in high-oxygen MAP were stored for 2 and 9 days and then displayed for 5 days at 1 degree celcius. Visual and instrumental color, metmyoglobin reducing ability (MRA), LDH activity in both directions (Lactate <----> Pyruvate), and NADH were measured. We found that steaks enhanced with 2.5% lactate showed the least visual discoloration, most color stability during display, and was most red at the end of display. Non-enhanced controls and enhanced steaks without lactates were most discolored. Steaks containing 2.5% lactate had significantly more LDH activity in both directions, produced more NADH, and had greater MRA compared with non-enhanced controls throughout display. These results suggest that lactate promotes color stability by the conversion of lactate to pyruvate via increased LDH activity and the concomitant regeneration of NADH. The NADH subsequently reduces metmyoglobin to either deoxy- or oxymyoglobin, thus increasing color stability of lactate-enhanced beef.
Session 68, Muscle Foods: Biochemistry, color and non-meat ingredients
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |