Changes of Water Distribution and Physicochemical Properties of Abalone (Haliotis discus ) Myofibrillar Proteins during Heat-Induced Gelation

Abstract

The effects of heating on water distribution of heated abalone myofibrillar protein (MP) were investigated using nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). Results of NMR spin–spin relaxation time (T2) and MRI suggested that, comparing with unheated MP the population of immobile water of heated abalone myofibrillar protein (A22) decreased by 66.69%, while that of free water (A23) increased by 5.8%, and the intensity of the T2 weighted images increased while T1 decreased throughout the heating, respectively. Storage modulus (G′) increased as gel formation occurred, but decreased after reaching the temperature of 25C until approximately 37C when G′ increased again. Modifications in the amide I (1,600–1,700 cm−1) regions indicated the α-helix of abalone MP gradually decreased with increasing temperature. Therefore, we hypothesized that heating resulted in immobile water shifting to free water partly, thus reduced the abundance of water and properties of heated abalone MP. Practical Applications This article illustrated the gelation degree of abalone MP induced by heating temperature. For better understanding the water–protein interactions of heated abalone MP and abalone products, NMR and MRI were employed to monitor the water distribution and mobility, and heated abalone MP physicochemical properties including secondary structure and rheological properties were evaluated in a heat induced system of MP, to simulate heat processing of abalone products, and to allow the manipulation of processing conditions of MP to obtain products with the desired textural attributes.