Post-rigor muscle is about 75% water, with up to 87% of the volume of the muscle cell being myofibrils, which contain the majority of the water. Muscle structure is comprised of soluble (sarcoplasmic, including myoglobin and calpain) and insoluble proteins (myofibrillar, cytoskeletal and connective tissue) and also water. We consider water to be a part of the structure, which not only allows diffusion and interaction of substrate and enzyme, but also determines plasticity, rigidity and gelatinisation of the insoluble proteins. Thus water-holding capacity (WHC) is not only important for visual and sensory acceptability and for economic reasons, but also because of its role in moulding muscle structure and the consequent effects on quality.