Moderate supplementation with extract of mate to a standard broiler diet in feeding experiment with 5 treatment groups was found to increase production of endogenous antioxidants in muscles, improving meat quality and storage stability. For addition of 250 or 500 mg extract per kg feed, pre-cooked meatballs made from the breast muscles had a significant lower level of secondary lipid oxidation products during one week of chill storage. Addition of 750 or 1000 mg extract per kg feed had an increasing prooxidative effect during storage of the meatballs. For the moderate levels of plant phenols in feed, a metabolic study based on nuclear magnetic resonance (NMR) spectroscopy of meat extracts showed that mate extract added to the feed increased the muscle level of antioxidative peptides like anserine, while indication of toxic effects was noted for the higher levels of feed additives. Rate of formation of radicals as detected by electron paramagnetic resonance (EPR) spectroscopy was found to correlate with the oxidative damage and a kinetic analysis demonstrated that the antioxidative effect of mate supplemented to the feed could be assigned to radical scavengers present in the meat. These findings for the monogastric animals are different from results previously obtained for ruminants, where plant phenols rather seem to affect the microflora of the digestive tract.

Aerobic metabolism changes rapidly to glycolysis post-mortem resulting in a pH-decrease during the transformation of muscle in to meat affecting ligand binding and redox potential of the heme iron in myoglobin, the meat pigment. The "inorganic chemistry" of meat involves (i) redox-cycling between iron(II), iron(III), and iron(IV)/protein radicals; (ii) ligand exchange processes; and (iii) spin-equilibra with a change in coordination number for the heme iron. In addition to the function of myoglobin for oxygen storage, new physiological roles of myoglobin are currently being discovered, which notably find close parallels in the processes in fresh meat and nitrite-cured meat products. Myoglobin may be characterized as a bioreactor for small molecules like O2, NO, CO, CO2, H2O, and HNO with importance in bio-regulation and in protection against oxidative stress in vivo otherwise affecting lipids in membranes. Many of these processes may be recognised as colour changes in fresh meat and cured meat products under different atmospheric conditions, and could also be instructive for teaching purposes.