Effects of frozen storage on the proximate composition and formaldehyde content in some selected fish from three different sources of southern Bangladesh

Abstract

The study was conducted in aims to investigate the effects of frozen storage and cooking conditions
on proximate compositions and formaldehyde content (FA) in some selected fish from three different sources
in Bangladesh. Proximate composition in fresh and final frozen samples was determined by standard AOAC
method and FA content in fresh, frozen stored, and cooked samples was determined by spectrophotometric
method. Among the studied fishes, marine fish contained higher protein (except Rita), lipid, and ash followed
by estuarine and culture fish samples. Protein, moisture and ash content decreased and lipid content increased
significantly (p<0.05) during frozen storage for all samples and sources. The FA was lower in cultured fish
samples compared to that of the river and marine fish samples, both at fresh and end of frozen storage. At
fresh condition, FA content in all samples ranged from 0.41 to 0.71µg/g, 0.51 to 0.89µg/g, and 0.73 to
1.69µg/g which increased to 0.95 to 2.11µg/g, 1.74 to 1.95µg/g, and 3.22 to 5.20µg/g at end of the storage
period, respectively (p<0.05). Further, FA content significantly decreased after cooking in all the fish
samples (p<0.05). However, irrespective of fish species and sources, the FA content was higher than WHO
recommended value (0.2 µg/g). The study findings revealed that longer frozen storage of fish could be a
public health concern to the consumers.