Indole as an Index of Spoilage of Mackerel (Rastrelliger kanagurta) during Storage at Ambient Temperature and in Ice

Abstract

A study was conducted to find out any correlation between indole and the spoilage indices such as Tri Methyl Amine Nitrogen (TMAN), Total Volatile Base Nitrogen (TVBN) and Total Bacterial Count (TBC) during spoilage of mackerel (Rastrelliger kanagurta) at ambient temperature and in ice. Mackerel had a shelf life of 6 and 9 h at ambient temperature based on the sensory evaluation of whole mackerel and cooked meat respectively. After 9 h of storage at ambient temperature TVBN, TMAN and indole were only 25.2 mg/100, 5.75 mg/ 100 and 0.3 |ig/100g respectively. The bacterial load was 5.55 log CFU/g. Mackerel had a shelf life of 6 and 9 days in ice based on the sensory evaluation of whole and cooked fish respectively. TVBN, TMAN and indole were only 14.35 mg/100, 0.67 mg/100 and 0.4 |ig/100g respectively. Total bacterial count was 6.36 log CFU/g. All the indices studied were low when the mackerel was rejected but this was specially true of indole which was detected in negligible amounts through out the storage period and also showed no trend through out. So indole was found to have no significance as an index of spoilage of mackerel kept at ambient temperature and in ice.