Denaturation and the Glass Transition Temperatures of Myofibrillar Proteins from Osmotically Dehydrated Tilapia: Effect of Sodium Chloride and Sucrose

Abstract

The effect of sodium chloride and/or sucrose content on the denaturation (T_d) and the glass transition (T_g) temperatures of osmotically dehydrated tilapia fillets using binary or ternary solutions at 20°C, was evaluated. DSC analyses revealed that myofibrillar proteins denaturation temperatures and enthalpies decreased with increase in muscle salt content. Sugar produced a stabilizing effect on denaturation of the fillets proteins. When ternary solutions were used, sucrose did not protect the proteins against the ionic stress produced by the salt. T_g was affected by the residual moisture content of the samples. Influence of NaCl was important at low water activity values. Sucrose content did not influence on T_g.

Keywords:

• Differential scanning calorimetry
• Fish
• Myosin
• Actin
• Osmotic treatments

ACKNOWLEDGMENTS

This work was supported by grants from FAPESP (Fundação de Amparo a Pesquisa do Estado de São Paulo), the Brazilian National Research Council (CNPq), and CAPES-Grices (Brazil-Portugal International Cooperation Project).

Notes

5. Medina-Vivanco, M. Estudo da difusão de cloreto de sódio no filé de tilápia (Oreochromis niloticus) utilizando volumes limitados de salmoura. Dissertação (Mestrado em Engenharia de Alimentos), Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas, 1998, 103.

30. Cheftel, J.C.; Cuq, J.L. Aminoacidos, Peptidos y Proteinas. Quimica de los Alimentos; Department of Food Science, University of Wisconsin-Madison; O.R. Fennema, Director; Editorial Zaragoza. 1984, 275–412.