Studies of soy sauce sterilization and its special flavour improvement by gamma-ray irradiation

Abstract

Experimental studies for sterilizing 12 kinds of soy sauce with gamma-ray irradiation showed that both of effects for sterilization and improving flavour and quality of soy sauce were obtained simultaneously. All colibacillus in soy sauce were sterilized using 1 kGy radiation dose and total bacteria count in soy sauce can be reduced to below national standard at 5 kGy dose ( 5x10 4count/ml ). But above 10 kGy dose is needed to kill all bacteria in soy sauce. The significant changes on chemical components in soy sauce irradiated at 5–7 kGy dose took place: raduceing-sugar increased by 1–10%, total amount of 18 kinds of free amino acid raised between 3.5–28 %, emerging-sweet smell substances which have low boiling point, such as alchols, aldehydes and esters obviously increased. The taste-specialists from some soy sauce factories concluded that flavour and quality of soy sauce irradiated are better than non-irradiated.