Effect of pH and the presence of NaCl on some hydration properties of collagenous material from trout (<i>Salmo irideus</i> Gibb) muscle and skin

Abstract Various hydration properties (solubility, water binding capacity and viscosity) of collagenous material from muscle connective tissue and skin are analysed in terms of pH and NaCl concentration in the medium. In general terms it is found that functionality is at its greatest where pH is between 2 and 4, and that the addition of NaCl reduces functionality, except in the case of viscosity. Both collagenous materials react similarly to changes deriving from pH and the addition of NaCl. The data are relevant to the possible utilisation of waste products from the fish industry as functional ingredients in other foodstuffs.