Effect of Formalin on the Sensory and Some Biochemical Attributes of Fish
Prof. Rony L. Villaflores, PhD

Abstract
Unscrupulous practice of some fish vendors uses formalin (40% solution of formaldehyde, CH2O) as preservative for fish especially when there are no available cool storage facilities and ice to preserve fish and fish products. Formalin being considered as highly toxic for human consumption could result to serious health hazard. Currently, there is no available tool in the local markets to detect formalin adulterated fishes and fish products that would safeguard consumers against the hazard of consuming fish treated with formalin. In order to develop strategies to detect formalin treated fish, this study was conducted to determine the fish quality and appearance based on sensory evaluation and some biochemical indicators. A controlled experiment was conducted using Chanoschanos Linn treated with 0%, 10%, 20% and 30% formalin and stored in ice. Sensory evaluation based on eye appearance, and odor smell of fish for 3 consecutive days showed no significant differences between treated and non-treated fishes. The pH and the trim ethylamine content if fish are not affected once the fish is preserved with formalin. Overall, the results showed that sensory evaluation based on fish eyes appearance and odor, as well as the pH and the trim ethylamine contents of fish cannot discriminate fish products treated with or without formalin. Further study should be conducted to develop alternative and sensitive method of detecting formalin in fish and fish products that could be used by authorities in monitoring the prevalence of formalin treated fish in the market.

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