Nature, Cause, and Control of Irradiation-Induced Off-Odor in Ready-to-Eat Meat Products

Abstract

Ionizing radiation improves food safety and extends shelf life by inactivating food-borne pathogens and spoilage microorganisms commonly found in ready-to-eat (RTE) meat products. However, irradiation may induce the development of an off-odor, particularly at high doses. The off-odor has been called "irradiation odor" and described as "sulfide", "wet dog" and "barbecued corn-like". Although the exact compounds responsible for the off-odor are not completely clear, substantial evidences suggest that volatile sulfur compounds (VSCs) play an important role in the development of the offodor. Many sulfur compounds, induced by irradiation, have low odor thresholds. These compounds include hydrogen sulfide, methanethiol (MT), methyl sulfide, dimethyl disulfide and dimethyl trisulfide. In comparison, thermal processing (heating and microwave) mainly induced MT and ethyl methyl sulfide. VSCs were presumably synthesized from sulfur containing compounds (such as methionine, cysteine, thiamine, glutathione) reacting with free radicals generated from water radiolysis. Antioxidants applied either as ingredients in raw meat emulsions prior to RTE manufacture or as post-manufacture dipping did not consistently reduce VSCs formation caused by irradiation. Research is needed to explore means of controlling the production of VSCs and offodor in irradiated RTE meat products.