Title

Role of Mitochondria in Postmortem Color Stability

Date of Completion

January 2012

Keywords

Agriculture, Animal Culture and Nutrition

Degree

Ph.D.

Abstract

Mitochondria remain active in postmortem muscle, consuming oxygen and influencing myoglobin redox state. The overall objective of the current research was to better understand the role of mitochondria in beef color. The results suggest that mitochondria have the ability to regenerate reducing equivalents when substrates such as succinate and lactate are available. This NADH produced via lactate-LDH-NAD resulted in mitochondrial oxygen consumption, conversion of oxy- to deoxymyoglobin, and metmyoglobin reduction (P < 0.05). However, 4-hyrdroxy-2-nonenal (HNE) influenced mitochondria ultrastructure and decreased oxygen consumption, electron-transport mediated metmyoglobin reduction, and NADH-dependent metmyoglobin reductase activity (P < 0.05). Mass spectrometric examination revealed that HNE adducted to LDH at both pH 5.6 and 7.4; and this interaction decreased NADH formation. Mitochondrial oxygen consumption can significantly influence both color development (myoglobin oxygenation) and color stability (myoglobin redox status). Given the inter-relationship between myoglobin and mitochondria, factors that influence mitochondrial activity will have a direct effect on beef color. ^