Oil Coating Affects Internal Quality and Sensory Acceptance of Selected Attributes of Raw Eggs during Storage


Direct inquiries to author Jangchud (E-mail: fagiavj@ku.ac.th).


 Four (coconut, palm, rice bran, and soybean) edible oils and glycerol were applied on eggshell. All noncoated and coated eggs were stored for 5 wk at 25 ± 2 °C and drawn weekly for quality evaluation. All oil coatings were more effective in preserving internal quality of eggs than was glycerol coating. As storage time increased, the preservative effects of edible oil coating on weight loss, and albumen and yolk quality were significantly noticed. Oil-coated eggs had significantly lower weight loss (<0.43%) than did noncoated (3.87%) and glycerol-coated (3.73%) eggs after 5 wk of storage. Based on the Haugh unit, oil-coated eggs maintained AA grade up to 3 wk. After 5 wk of storage, noncoated, glycerol-coated, and oil-coated eggs changed from AA grade to below B, below B and A grade, respectively. The albumen pH of noncoated and glycerol-coated eggs considerably increased from 8.23 to 9.51 and 9.42, respectively, while those of oil-coated eggs either maintained or slightly increased to 8.32. The albumen viscosity of all eggs decreased with increased storage time. Consumers (N = 120) could differentiate surface glossiness of oil-coated eggs from uncoated eggs (R-index of 81.42% to 86.99%). All oil-coated eggs were acceptable for surface glossiness (liking scores of 6.22 to 6.77) and surface odor (liking scores of 6.20 to 6.55) with overall liking scores of 6.34 to 7.03. Overall, this study demonstrated that edible oil (coconut, palm, rice bran, and soybean) coating could preserve internal quality of eggs (maintaining grade A) at least 4 wk longer than noncoated eggs.

Practical Application:  Freshness is a major contribution to the egg quality. The internal quality of eggs begins to deteriorate after they have been laid due to loss of moisture and carbon dioxide via the eggshell pores. Refrigeration is very effective in preserving egg quality. Surface coating is an alternative method to preserve egg quality, although it is much less effective than refrigeration. This study demonstrated that coconut, rice bran, soybean, and palm oils, which are abundant and commonly consumed in many parts of the world, could preserve the internal quality and reduce weight loss of oil-coated eggs during room temperature storage.