Influence of inorganic iron, lactate, and succinate on myoglobin redox stability, color, and mitochondrial activity of raw beef
Purohit, Anuj Subhash
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Enhancing beef with metabolic intermediates lactate and succinate is known to improve raw beef color. This work examined the effect of inorganic redox active iron in combination with the named metabolites on the color and myoglobin redox stability of raw beef homogenates and their effect on the respiration of isolated beef heart mitochondria. Homogenates treated with the combination of redox iron and metabolites had significantly lower redness values (p<0.05). Inorganic redox active iron ions adversely affected mitochondrial structure and function. The rates of mitochondrial oxygen consumption driven by either of lactate or succinate were significantly reduced in the presence of redox active iron ions. The results indicate that inorganic redox active iron is deleterious to color of raw beef muscles and also to mitochondria which are a medium of color stabilization in fresh beef. Variation in concentration of heme and nonheme iron forms in two muscles of differing color stability and how it correlated to color and lipid oxidation was monitored over a nine day period of refrigerated storage. Heme iron concentration correlated strongly with redness and lipid oxidation and moderately with discoloration. Nonheme iron concentration correlated poorly with redness and discoloration and moderately with lipid oxidation. Variation in concentrations of different iron forms does not completely explain changes in raw beef color and associated quality parameters, regardless of muscle type. Thus, factors along with iron form concentrations need to be holistically considered when developing and marketing products of raw beef muscles of differing color stabilities.