Effect of dynamic high pressure on fish bacteria: a case study

Abstract

We have examined the effect of dynamic high pressure on the load of spoilage as well as pathogenic bacteria in 'Indian Mackerel', a popular fish item available in Bombay. The 63 mm bore gas-gun was used to impart dynamic pressures of about 4-7 kbars lasting for a time period of around 4us in the fish samples. The temperature of the specimen in compressed state was estimated to be 15 - 25 C above ambient. Five experiments have been conducted: two on fresh fish samples, two on spoiled fish samples having 1011/gm bacterial load and one on the sample inoculated with Salmonella typhimurium, a pathogenic bacterium. On shock loading, the bacterial load reduction in the fresh fish samples was found to be 1-2 log cycle reduction of Salmonella was observed in the inoculated fish sample. These experiments show that the short duration, high pressure shock treatment could be used as a novel method in reducing microbial contamination of fishery products.