Development of fish freshness assessment sensor

Abstract

Considering the increasing awareness and raising standards of food safety, finding out the freshness of the captured fishes available in the market or landing centres is much needed in view of increased use of chemicals used for preserving fishes. In this regard, a study has been conducted at ICAR-Central Institute of Fisheries technology, Kochi to find out the freshness indicators of fish for development of a sensor. Fresh Indian mackerel was procured from fish landing centre Kalamukku, Kochi, Kerala. The parameters considered to be depicting the extent of freshness of fish after it was caught were analyzed to get status of freshness. Color of fish eye, gill and skin were analysed by taking L,a,b color values using Hunter Color Lab. pH of mouth fluid and blood in belly bottom were tested. Trimethylamine, Total Volatile Nitrogen values of fish flesh was also analyzed to quantify the extent of spoilage. All the analyses were carried out for a period of 7 days with one day interval. In total, five experiments were conducted in which each experiment had 6 samples analyzed over 7 days storage period. The results revealed that the color values of skin and gill were not following any particular trend with respect to storage days. However, in color values of fish eye, reduction in the L value and increase in a value was observed with storage days. The cross examination of Hunter color values with the color of physical photograph also concurred with fish eye color, which turned dark and reddish at the end of storage. The spoilage indicators like TMA and TVN also indicated the extent of spoilage and those values were interpolated to get benchmark color values for fish eye to decide the level of fish freshness.