Sorption isotherms and the state diagram for evaluating stability criteria of abalone

• Published in: Food research international 2004, Vol.37 (10), p.915-924
• Main Authors: Sablani, S.S., Kasapis, S., Rahman, M.S., Al-Jabri, A., Al-Habsi, N.
• Format: Article
• Language: English
• Subjects: abalone; adsorption; Biological and medical sciences; cold stability; cooling; Cooling curve; equations; Fish and seafood industries; Food industries; food quality; freeze drying; freezing point; Fundamental and applied biological sciences. Psychology; glass transition; Glass transition temperature; Haliotis; mass transfer; mathematical models; Sorption isotherms; Water activity; water content
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2004.05.006

Water adsorption isotherms and the state diagram of abalone were developed to further investigate the connection between the two distinct criteria of food stability. The isotherms were measured at 23, 40 and 60 °C using an isopiestic method and they were treated with appropriate models available in the literature. The state diagram was developed using freezing points, as derived by the cooling curve method, and glass transition temperatures were measured by dynamic oscillation on shear. The limited glass transition process of the abalone network necessitated derivation of the mechanical glass transition temperature, since the transition could not be detected using MDSC. Results indicate that there is a considerable discrepancy in the temperature-related stability criteria predicted by the concepts of water activity ( a w) and the glass phenomenon ( T g). In contrast to the progressive deviation between a w and T g with increasing molecular weight reported earlier for a homologous family of materials, the effect of rising temperature produces a constant index of comparison between the two concepts.