Effect of formaldehyde on shelf life of fresh fish
1993
Dusadee Tunhun
Survey on formaldehyde (FA) content in rake-gilled mackerel (R.G.M.) (Rastelliger karnagurta Cuvier) sold in Bangkok indicated that FA was not added. The lowest concentrations of FA which could be detected by sensory evaluation were 500 and 2,000 ppm in R.G.M. and lizard fish (L.F.) (Saurida sp.), respectively, but the lowest concentrations detected by chemical method were 100 and 500 ppm which were the lowest concentrations used in this study. Formaldehyde was produced in a small amount during storage of R.G.M., the concentration of FA increased during frozen storage from 0.05 mg/100 g to 0.14 mg/100 g at the 24th week. L.F. produced FA during storage as well, the concentration increased from 1.68 mg/100 g at the beginning to 4.25 mg/100 g after 24 weeks of frozen storage. The effect of FA in preservation using TVB as a freshness index, FA at 0-1,000 ppm had no effect on TVB content in R.G.M. (P0.05), however the better physical appearance of the fish was detectable. FA at 0-2,000 ppm in L.F. affected the TVB content (P0.01) during storage at room temperature. During keeping in ice, FA at 500 and 4,000 ppm affected the freshness of both treated fish organoleptically. The highest concentration of FA had shown the best result. During frozen storage, FA at 500 ppm had no effect on both treated fish as indicated by TVB content which showed a trend to increase at longer keeping time. Nevertheless, the content of TVB as well as the physical appearances were not much different during each sampling.
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