Effects of Gamma Radiation on Sensory Qualities, Microbiological and Chemical Properties of Salted and Fermented Squid

Abstract

The effects of gamma radiation on sensory quality, microbial population, and chemical properties of salted and fermented squid were investigated. Squid (Todarodes pacificus) was sliced, washed, and then salted with 5, 10, and 20% (wt/wt) sodium chloride. Salted squid was irradiated with dosages of 0, 2.5, 5.0, and 10 kGy of gamma radiation and fermented at 15°C for 50 days. Proximate composition, salinity, water activity, sensory evaluation, and total microbiological populations were examined. Chemical analyses providing information on degree of fermentation, such as amino nitrogen (AN), volatile basic nitrogen (VBN), trimethylamine (TMA), and hypoxanthine (Hx) were also conducted. Irradiated squid was not different in proximate composition, salinity, and water activity from nonirradiated squid. Sensory evaluation scores, total bacteria populations, and pH values were variable depending on salt concentration and irradiation dose. During fermentation, AN, VBN, TMA, and Hx contents increased rapidly as the salt concentration and irradiation dose decreased. Specifically, these chemical compounds of salted and fermented squid prepared with 10% salt and 10 kGy of gamma radiation maintained the appropriate level of fermentation. The present results showed that the combination of low salt concentration (10%) and gamma radiation was effective in processing salted and fermented squid and extending its shelf life compared to control (20% of salt) without adding any food additives.