Evaluation of Methods for Determination of Moisture Content of Heavy Saltd Cod, Gadus morhua

Abstract

Moisture contents of various grades of salted cod were determined directly by the standard oven method and Compu-Trac™ procedures. A predictive approach was also tested using data collected with a Hygrodynamics water activity meter. The coefficient of variation (cv) for moisture determination of 47 samples ranged from 0.2 to 2.3% and averaged 0.96% for the oven method and ranged from 0.1 to 1.2% moisture and averaged 0.63% for the CompuTrac™ method. The coefficient of determination (r2/for linear regression analysis of moisture determination by the two methods was 0.99 for the equation:(% H2O, oven method) = .96 (% H2O, Compu-Trac method) + 3.3%The desorption isotherm at 5°C for a single lot of intact heavy salt fish, 50.7% H2O which was stepwise dehydrated to 11.7% H2O, exhibited a typical hyperbolic plot: (% H2O)=77.24×100Aw)/(1.82+100Aw) with a coefficient of determination of 0.99. However, the relationship between Aw and % H2O for 26 commercials samples, ranging in water content from 27.2 to 52.0%, was ambiguous. The salt content of 26 commercial samples of heavy salt fish ranged from 37 to 49% of the total solids. The variable salt content of commercial fish was largely responsible for the lack of correlation between Aw and moisture content.