Mathematical modeling of the heat transfer process and protein denaturation during the thermal treatment of crabs from the Argentine Patagonia

JIMENA B. DIMA, PEDRO J. BARÓN, NOEMI E. ZARITZKY

Procedia Food Science

ELSEVIER

Año: 2011 p. 729 - 735

2211-601X

Off the coast of Patagonia, Argentina, crab species such as the Southern Ocean swimming crab Ovalipes trimaculatus and the Patagonian stone crab Platyxanthus patagonicus are considered fishing resources of commercial value. Although in Argentina the commercialization of crabs is incipient, in the last years it began to generate interest due to the consumer acceptance of the crab meat. Thermal treatment of crabs must be sufficient to denature muscle proteins, facilitating meat detachment from the crab shell, however, excessive heat exposure is associated to texture deterioration. The objectives of the present work were: a) to mathematically simulate the energy transfer during the thermal process of crabs using a finite element computational code; b) to determine the denaturation kinetics of proteins during heating c) to establish the degree of denaturation achieved by the myofibrillar proteins during the heating process by coupling the protein denaturation kinetics, the activation energies and the thermal penetration curves. Crabs were captured by SCUBA diving manual and trapping on the sea of Golfo Nuevo, Argentina. They were transferred alive to the laboratory, and sectioned in body and claws. These parts were thermally treated in controlled temperature water baths at 70, 80, 90, 100ºC, during 20 seconds and 25 minutes. Time-temperature curves were recorded by using inserted thermocouples. The heat transfer process was mathematically modeled, considering the irregular geometry of the system; the heat transfer partial differential equation was numerically solved using finite elements (Comsol Multiphysics). The denaturation kinetics of the thermal treated myofibrillar proteins wasdetermined using Differential Scanning Calorimetry (DSC). DSC thermograms of raw crab muscle revealed the presence of two peaks: Tmax1=49.02°C (myosin) and Tmax2=77.47ºC (actin). The kinetic coefficients of myofribillar protein denaturation were determined at different temperatures and activation energies were 145.70 KJ/mol for myosin and 156.42 KJ/mol for actin. The degree of denaturation achieved by the myofibrillar proteins in the heating process was determined by coupling the protein denaturation kinetics, the activation energies and the thermal penetration curves. This information allowed the development of the technological process for both species for an effective marketing of the products.