Actin as a candidate quality marker for food of animal origin

Most of the relevant meat and meat-product quality characteristics are the results of the chemistry of protein and peptides. Therefore, the inclusion of information on protein differences provided by protein markers can make a significant contribution to the improvement of meat and meat product quality. Actins are a family of highly conserved proteins, which play fundamental roles in nearly all aspects of eukaryotic cell biology. In the skeletal muscle, in addition to the highly specialized contractile apparatus, there are both the actin-associated costameric complexes and the functionally distinct cytoskeletal actin-based filaments. Ante mortem muscle biochemistry strongly influences post mortem biochemical processes which, in turn, are linked to final quality attributes, including texture which is one of the most important attributes of muscle foods. However, there is very little knowledge on the way in which ante mortem biochemistry changes the post mortem events and hence the resulting final quality. The understanding of post mortem mechanisms is essential for predicting the final quality in terms of texture. The histochemical and biochemical evidence indicates that much of the tenderization associated with post mortem aging is due to the action of the enzymes, which are known to be endogenous to the muscle. Interestingly, the most abundant proteins of the myofibril, actin and myosin, are not significantly degraded during post mortem aging. However, an extensive apoptosis could lead to a progressive degradation of cytoskeletal and thin filaments of actin, resulting to meat tenderization. The investigation on how actin degradation affects meat and meat product quality is still nascent, but the results reported in this PhD thesis seem promising. Indeed, the main activities have been directed to evaluate the potential use of actin as a biochemical marker for the prediction of muscle food quality in three Italian PDO dry-cured hams and in farmed sea bass. In the first part of this thesis, a brief general introduction on the muscle composition in mammals and fish and on the post mortem events occurring in muscle is reported, followed by a description of the characteristics of dry-cured hams and sea bass like food products of animal origin. Therefore, the two papers related to the above reported topics are attached, accompanied by some conclusive remarks