EFFECT OF ELECTRON-BEAM IRRADIATION CON PHYSICAL, PHYSICOCHEMICAL, AND FUNCTIONAL-PROPERTIES OF LIQUID EGG-YOLK DURING FROZEN STORAGE

Raw yolk of 1-d-old eggs was either subjected to linear electron beam irradiation at similar to 2.5 kGy dosage or not processed. Both irradi ated and nonprocessed egg yolk samples were stored at -15 C after irra diation. Testing was conducted on 0, 1, 7, 15, 30, and 60 d of storage . Development of storage modulus (G') was delayed in irradiated sample s after 7 d, which suggests that less structure was developed in irrad iated egg yolk than in nonprocessed egg yolk during storage. Irradiate d samples retained more soluble protein within the first 7 d and showe d slightly improved emulsion capacity over that from nonprocessed samp les. However, irradiated egg yolk was less bright than nonprocessed sa mples. No difference were observed in SDS-PAGE patterns of soluble pro teins and delipidized low density lipoprotein (LDL). The LDL isolated from irradiated liquid egg yolk showed no difference in N-terminal ami no acids compared to that of nonprocessed egg yolk, indicating no dete ctable cleavage of LDL. However, the denaturation temperature of irrad iated samples at Day 0 shifted about 1 C lower than that of the nonpro cessed sample. Results indicated that electron beam irradiation did no t cause significant physical, chemical or functional changes of egg yo lk, or cleavage of egg yolk protein. Therefore, electron beam irradiat ion could serve as a preservation method for liquid egg yolk.