Heat penetration and shelf life evaluation of prawn curry processed in multilayer containers in steam and water immersion retorts

Abstract

RTE shelf stable prawn curry was developed in multilayer thermoformed polypropylene containers of 320 ml capacity. The prawn curry was prepared as per standard recipe and packed 60:40 liquid to solid ratio. Hot filling was done and the containers were heat sealed in a pneumatic tray sealing machine. The sealed containers were split into two batches of which one was thermal processed in a steam air retort and the other in a water immersion retort to Fo value of 8 min at 121.1 degree celsius. The medium of heating was steam and air for steam retort and in water immersion it was water and steam. The total process time to reach Fo value of 8 was 47.28 min for steam air and 52.30 min for water immersion retort respectively. The thermal processed samples were sterile throughout the storage period. The samples were evaluated on a monthly basis for biochemical and organoleptic parameters. The TVBN values did not show any significant changes during storage. The lipid oxidation parameters like free fatty acid and thiobarbituric acid value increased marginally. The L values decreased during the period of storage and the texture of the samples became harder during storage. Organoleptically the samples were acceptable upto 10 months of storage.