Effect of polylysine and butter-based coating on quality properties of eggs

We have studied the impact of polylysine-based coating on selected quality attributes of eggs stored for 35 d at 25°C. Overall, 252 fresh eggs were divided into 4 groups: 1) no coating (control); 2) ε-polylysine hydrochloride coating (ε); 3) ε-polylysine hydrochloride and Tween-80 (ε+T); and 4) ε-polylysine hydrochloride, Tween-80, and butter coating (ε+T+B). Compared to those of the control, ε+T and ε+T+B eggs displayed higher Haugh unit (63.03 and 70.12%, respectively), YI (0.34 and 0.38, respectively) after 28 d, and lower weight loss (0.78–9.41%), air cell depth (7.53–15.20 mm) and diameter (1.77–3.03 cm) after 14, 28, and 35 d. The lowest pH was obtained in ε+T+B coated eggs after 35 d at 25°C. After 21 and 35 d, the ε+T+B eggs had improved values of eggshell breaking strength (34.78 and 46.02 N, respectively) relative to those of control. Microstructure images through SEM, FTIR spectra, water contact angle, and antibacterial assessment demonstrated that ε+T+B-coated eggs had a firmer, wetter, and antibacterial shell surface with less cracks or destruction due to enhanced and intertwined interactions in coating components, thus contributing to egg preservation. In conclusion, ε+T+B preserved the internal quality of eggs stored after 35 d at 25°C.