Studies on Defrosting of Frozen Foods (Part 2)

Defrosting of Frozen Merurusa (Merluccius dayi) in Water

Abstract

Merurusa and other frozen foods are commonly defrosted in water. The conditions to thaw frozen Merurusa with a minimum loss of nutrients were determined at 18.8°C and 28.8°C, corresponding to the temperatures of water in spring and summer, respectively. Weighed samples of Merurusa were defrosted in beakers containing known amounts of water. The Merurusa in each sample was then pressed under a weight. The total amount of nitrogen in the pooled water and fish exudate was determined by the Kjeldahl method. At 18.8°C the best conditions to defrost Merurusa were 20 minutes with a fish : water ratio of 0.3 (30%) and a loss of total nitrogen of only 3%. At 28.8°C, however, the best conditions were also 20 minutes with a fish : water ratio of 0.4, when there was a loss of total nitrogen of 6%.