Effect of freezing temperature, thawing and cooking rate on water distribution in two pork qualities.

The effects of freezing temperature (-20 versus -80°C) in combination with long-term freezer storage (-20°C) on water mobility and distribution in pork of two qualities (normal and high ultimate pH) were explored using low-field NMR T(2) relaxometry. A marked effect of freezing temperature on the characteristics of intra- and extramyofibrillar water (T(2) relaxation times) in the thawed pork was demonstrated, implying that the freezing temperature in combination with prolonged freezer storage affects the distribution and chemical-physical state of water in the thawed meat. Determination of technological properties (thawing and cooking loss) revealed that the observed T(2) variations related to water distribution and water properties, which were found to be consistent with the degree of structural damage assessed by light microscopy, also were reflected in the technological quality of the meat.

Cooking effects on water distribution in potatoes using nuclear magnetic resonance relaxation.

Continuous low-field (LF) (1)H NMR relaxometry was used to monitor the structural changes during cooking of potatoes with two different dry matter (DM) contents. A principal component analysis of the relaxation decay curves revealed major events related to water mobility during cooking, which occur at 53 and 60 degrees C for potatoes with medium and low DM contents, respectively. Exponential analysis of the relaxation decays reveals two major water populations in the potato: a slow-relaxing (assigned to water in cytoplasm and extracellular cavities) water component, T(22) ( approximately 350-550 ms), and a fast-relaxing component (primarily assigned to water associated with starch and cell walls), T(21) ( approximately 45-65 ms).