SUMMARY– Drying of salted fish was studied in the falling rate period. It was found that this period consisted of two distinct phases, each of which was characterized by a Fickian diffusion coefficient. The coefficient for the first phase was, in all cases, greater than that for the second phase. The effect, on both diffusion coefficients, of the following variables was studied: degree of salting, drying temperature, and degree of hydration of -the muscle (varied by addition of acid, base and sodium trypolyphosphate to the muscle). The first diffusion coefficient was found to increase, pass through a maximum, and then decrease with degree of salting. The second coefficient was found to decrease with degree of salting within the range for which it was determined.

The first diffusion coefficient was found to be directly correlated with the degree of hydration of the muscle; a plot of the coefficient versus water content of the muscle (expressed as pounds of water per pound of bone-dry solids) yielded a straight line, the regression equation of which was found to be D = 0.16W + 0.09, where D is the diffusion coefficient in cm2/sec × 105 and W is the water content. Variations in the diffusion coefficient due to degree of salting and due to addition of acid, base, and phosphate could be explained by the hydration-dependence of the coefficient. The temperature variation of both coefficients was found not to be great.