AUTHENTICATION OF THE EFFECT OF FREEZING THAWING OF PORK BY QUANTITATIVE MAGNETIC-RESONANCE-IMAGING/

Magnetic resonance imaging analysis of longitudinal relaxation times ( T-1 values), transverse relaxation times (T-2 values), magnetization t ransfer (MT) rates and apparent water diffusion coefficients (a) was u sed to authenticate the effect of freezing/thawing in longissimus dors i pig muscle; these NMR parameters were compared with the gravimetric moisture content values obtained independently by oven drying, A signi ficant increase in the MT rate was observed between fresh and frozen/t hawed pork prepared from the same animal; however, measurements of oth er parameters showed little or less significant changes, The significa nt increase in the MT rate is associated with both the decrease of moi sture content in pork after freezing/thawing and with the denaturation of myofibrillar proteins in frozen/thawed pork. On that basis, the pr esent NMR results imply that the duration of the freezing period (from 2 weeks to 2 months at -18 degrees C) did not significantly enhance t he denaturation of the meat proteins. (C) 1997 John Wiley & Sons, Ltd.