Transformation of egg-white glass into partially crystallized glass induced by heat treatment and gamma-ray irradiation

Egg-white gel is easily transformed into transparent “glass" by drying at ambient temperature, e.g. at 25° C for 140 min. The optical transmittance is increased from 2 to 25% accompanied with a decrease in the weight by more than 70%. Broad and intense IR absorption peaks observed at 3288–3308 and 1653–1657 cm^-1 were respectively assigned to ν (NH) and ν_α(C=O) stretching modes in the amido (RCONH-) groups, and the δ(NH) bending mode was observed at 1521–1546 cm^-1. Differential thermal analysis (DTA) study showed a distinct endothermic peak due to the glass transition, and the peak position was located at 36, 42, 58 and 69° C when the heating rates were 2, 5, 10 and 20° C min^-1, respectively. Heat treatment of egg-white glass at 60° C or γ-ray irradiation resulted in partial crystallization, and the XRD patterns showed a few diffraction peaks superimposed on the halo peak due to the glassy phase.