Rice protein coating in extending the shelf-life of conventional eggs

Abstract

The effectiveness of rice protein coat- ings or mineral oil on maintaining interior quality and eggshell breaking strength of fresh eggs was evaluated during storage at 20◦C for 8 wk. Egg quality was as- sessed by weight loss, Haugh unit (HU), albumen pH, yolk index (YI), shell strength, and scanning electron microscopy in uncoated eggs (control treatment) and eggs coated with mineral oil or rice protein concen- trate at 5, 10, or 15%. The HU and YI were higher in coated eggs (P < 0.001). Weight loss increased (P < 0.001) during long-term storage. Uncoated eggs showed the highest weight loss (8.28%), whereas min- eral oil (0.87%) and rice protein at 5% (5.60%), 10% (5.45%), 15% (5.54%) solutions were effective in pre- venting weight lost (P < 0.001). The use of the coat- ings preserved the internal quality of the eggs for up to 4 wk longer than uncoated eggs (HU, YI, and pH). Uncoated eggs had the worst (P < 0.001) HU (54.45), albumen pH (9.18), and YI (0.28) after 8 wk of stor- age. Among the coated eggs, the mineral oil had the best values of HU (70.54), pH (8.48), and YI (0.35) af- ter storage. The eggs coated with 5, 10, and 15% of rice protein presented results with similar intern quality be- tween them and intermediary quality in relation to the others treatments during all the storage period. Scan- ning electron microscopy demonstrated a lower surface porosity in coated eggshell, indicating that the use of the coating may provide a protective barrier against the transfer of gases and moisture. In conclusion, the use of coatings based on rice protein concentrate or mineral oil influences the internal quality of eggs during stor- age and may be an effective alternative for increasing the shelf-life of commercial eggs.