Gelation Properties of Comminuted Meat Paste from Cold and Warm blooded Species as Affected by Rapid Heating

Abstract

The hypothesis was tested that total thermal input, rather than merely heating rate, is the determining factor in heat-induced gel formation by muscle proteins. Comminuted pastes (2% NaCl and 78% total moisture content) made from Alaskan pollock surimi and turkey breast were heated at 0.5oC/min, 20oC/min or 80/98oC/min to 70°C and held up to 40 min prior to cooling. Fracture stress and strain, rigidity modulus (G'), cook loss and acid phosphatase activity were measured following each treatment. Results showed that rapid heating plus a brief holding time at the endpoint temperature produced similar meat gel textural properties as those cooked by a conventional slow ramp heating just to the same endpoint temperature. Thus the thermal input of the process, above the activation energy of protein denaturation leading to gelation, can be predictive of the resulting gel properties. Moreover, this indicates that the equivalent point method can be used to identify a range of process parameters which would yield cooked protein gels of desirable properties. Additionally, rapid heating, with advantages of process efficiency, space, and control, can likely be utilized by processors of certain muscle foods without compromising product quality.

Rapid heating for preparation of cylindrical (1.9 or 3 cm dia) surimi gels by ohmic and a new focused microwave applicator were compared to conventional heating of gels in a water bath at 90 or 100°C. Both rapid heating methods (ohmic and microwave) produced superior gels from a surimi blend containing significant heat-activated protease activity as compared to water bath heating at either temperature. These were comparable to preparing gels from the same surimi by water bath with the addition of beef plasma as a protease inhibitor. Ceramic end caps on the teflon tubes used for microwave processing improved the uniformity of heating by microwave. Gels prepared from protease-free surimi in 3 cm casings by microwave heating did not achieve similar results to the same gels made by water processing, which likely resulted from the microwave unit being under powered and not properly focused.