Plasticizer types and whey protein coatings on internal quality and shelf life of eggs stored for 42 days

Abstract

Effects of plasticizer types and whey protein concentrate (WPC) as coatings were evaluated on internal quality and shelf life of eggs stored for 42 days. Eggs were coated with WPC at 8 % solution combined with the plasticizers glycerol (GLY), sorbitol (SOR), and propylene glycol (PRO). The eggs were stored at 20 °C. Weight loss, Haugh Unit (HU), albumen and yolk pH, and yolk index (YI) were evaluated weekly from day 0 to 42 days. After, electron microscopy of the eggshell structure was performed. The data was submitted to the analysis of variance and the effects of treatment, storage time, and the interaction between these factors were evaluated. There was significant interaction between factors (treatment and periods) for weight loss (p < 0.0001), HU (p < 0.0001), albumen (p < 0.0001), and yolk pH (p < 0.0001), and YI (p < 0.0001). After 42 days, uncoated eggs showed greater weight loss (5.4 %), compared to WPC+GLY, (3.8 %), WPC+SOR (3.3 %) and WPC+PRO (3.9 %). Similar results were verified for HU at 42 days of storage. Uncoated eggs showed HU of 58.46 (B), while coated eggs showed higher values: WPC+GLY – 66.58 (A), WPC+SOR – 68.79 (A), and WPC + PRO – 71.53 (A). The plasticizers GLY, SOR and PRO, associated with WPC, demonstrated effectiveness in maintaining the quality of eggs throughout the 42 days of storage. However, WPC+SOR showed superiority in preserving quality integrity of eggs. This result can be related to the chemical structure of SOR, making the combination more efficient for storage.