Sulphur amino acids, muscle redox status and meat quality: More than building blocks - Invited review.

Advances in food science ineludibly require a profound study of food chemistry fundamentals. Consequently, we need to explore the environment where life and all underlying biological processes occur: the molecular level. The progress made in the last few years in relation to meat protein biochemistry enables revisiting the role that sulphur amino acids (SAA) play as redox-active muscle components. Beyond their participation as building blocks in the de novo synthesis of muscle proteins, protein thiols and other sulphur-containing species are active in controlling metabolic pathways, enzymatic processes, and redox reactions. Supplementation of SAA over nutritional requirements has been found to protect muscle lipids and proteins against oxidation, with subsequent benefits in terms of water-holding capacity, colour stability and sensory properties. As strong nucleophilic compounds, protein thiols establish assorted molecular interactions with other meat and non-meat electrophilic species (i.e. phytochemicals). Those interactions have been found to display remarkable effects on the redox properties, functionality and digestibility of meat proteins. The comprehension of these chemistry fundamentals enables a rationale manipulation of SAA via animal nutrition and/or food formulation to guarantee meat quality and safety and furthermore, develop novel, safer and more nutritious muscle foods, with increased oxidative stability.