Fish is a rich and affordable source of good quality protein and other valuable nutrients like poly unsaturated fatty acids (PUFA), vitamins and minerals. Recently there are reports on marketing of fishes added with harmful chemicals like formaldehyde, ammonia etc. Formaldehyde is a toxic aldehyde, listed as cancer causing agent by the International Agency for Research on Cancer and ammonia, although it is not carcinogenic, but continuous ingestion of ammonia can lead to hazardous health issues like injuries to mucous membranes of mouth, throat, esophagus, and stomach. Marketing of adulterated fishes with these chemicals can lead to serious health problems among the fish consumers. As the conventional techniques available for testing these harmful chemicals are time-consuming and erroneous also; so ICAR-Central Institute of Fisheries Technology has developed a low-cost, users’ friendly Paper Strip methods for rapid detection of formaldehyde and ammonia in fishes.
These detection methods are simple, rapid and based on visual observation of color development within a span of 2-3 minutes. There are two separate kits for detecting the presence of formalin and ammonia in fish. Each kit includes 25 testing strips along with a reagent solution and a standard colour chart to assess the extent of contamination by either formalin or ammonia. The strip has to be scraped on the surface of fresh fish or fish meat, and then 1-2 drops of the reagent solution can be added to see any colour change occurs which can be compared with the attached colour chart for easy detection of adulterants in domestically marketed fish. In case of formalin, if the colour that appears on the strip is light pink, then the sample is free from formalin. If the strip turns green on adding reagent and develops further to become deep blue, then in that case the level of formalin will be between 20-100 mg per kg, which indicates the fish is not safe for consumption. Similarly, in case of excess ammonia contamination, the colour will be deep blue showing the ammonia content more than 300 mg per kg. If the level of ammonia ranges between 100-300 mg per kg and less than that, then the fish is safe for consumption with a colour indication of light blue preceded by light green, when the level of ammonia is below 100 mg per kg.
This path breaking technological achievements of ICAR-CIFT will ensure the safety and quality aspects of fishes available in the market, this in turn will indirectly discourage the malicious adulteration by the traders in the sector. The technology has also been validated through some sample testing at different places.
(Source: ICAR-Central Institute of Fisheries Technology)