Developments in our understanding of water holding in meat

Muscle is an extremely complex biological material where biochemical, chemical, and physical changes are going on during all its existence. Physicochemically, muscle is a water phase with nanosized structural particles and soluble molecules. Water is held by an unknown mechanism, but most probably due the interactions between sarcoplasm and structural proteins, in the dense three-dimensional network of structural proteins, and partly compartmentalized by different membranes, such as sarcolemma, endomysium, and perimysium. In living muscle, the water is well held and controlled dynamically, but after death, 2%–6% or more water will be liberated, and in cooked meat much more. In raw whole meat or in large pieces or raw muscle, structural elements and membranes have a decisive role, but in comminuted meat, myofibrils and solubilized structural proteins take a decisive role. In the chapter, the roles of electrostatic, osmotic, and capillary forces relative to the mechanisms of water-holding are discussed, as well as the aspects of muscle microstructure. For water-holding capacity, the longitudinal structures, myosin shaft and actin filaments, have been the main focus, but the structural aspects and denaturation of myosin S1 + S2 subfragments seem to have a greater role in water-holding capacity than earlier has been anticipated. The structure of myowater, the role of cross-bridges in water holding, and technological aspects will also be shortly discussed.