Origin of multiexponential T-2 relaxation in muscle myowater

To obtain a further understanding of the nature of the multiexponential T L relaxation seen in muscle tissue water (myowater), relaxation measurements were carried out on whole, minced, and homogenized pork of three different qualities with regard to water-holding capacity (normal, red soft exudativ e, and dark firm dry). Whole, minced, and homogenized pork all resulted in multiexponential T-2 relaxation (three components) independently of the qua lity, even though microscopic studies on homogenized meat revealed consider able disruption of the macroscopic structure. This states that the relaxati on behavior in meat cannot be explained by intra-/extracellular compartment alization of the water as suggested in earlier studies. Subsequent studies of T-2 relaxation in either whole meat, where the structure integrity was c hanged by the introduction of dimethyl sulfoxide (membrane disruption) or u rea (protein denaturation), or minced meat with added NaCl (inter-/intrapro tein interactions) lead to the suggestion that in whole meat (i) the fastes t relaxation component reflects water tightly associated with macromolecule s, (ii) the intermediate relaxation component reflects water located within highly organized protein structures, for example, water in tertiary and/or quaternary protein structures and spatials with high myofibrillar protein densities including actin and myosin filament structures, and (iii) the slo west relaxation component reflects the extra-myofibrillar water containing the sarcoplasmatic protein fraction. Finally, relaxation patterns in heat-s et gels of superprecipitated actomyosin and bovine serum albumin similar to that identified in whole meat support the proposed nature of T-2 relaxatio n in muscle myowater.