Effects of two plant waxes as a coating material on internal attributes of chicken eggs stored under room temperature

Abstract

Surface coatings of eggs are used to extend the shelf life and minimize economic loss. Edible mineral oil is used as a coating material but several problems associated with it and plant waxes are tested as alternatives. "Boomi" (Litsea glutinosa) and "dawul kurundu" (Neolitsea cassia) is found throughout Sri Lanka and barks of these trees are widely used in indigenous medicine due to their antibacterial properties. But, information on these waxes on egg quality attributes does not exist. Objective of this research was to check the effect of "boomi" and "dawul kurundu" waxes as an external coating material on shelf life and internal quality of chicken eggs stored under room temperature. Total of 372 freshly laid brown, medium sized (55-60 g), clean eggs were purchased from a layer farm. Eggs were individually weighed and coated with "boomi" wax (1.0:6.5), "dawul kurundu" wax (01:10) and mineral oil while non coated eggs were used as negative control. Weight loss, change in air sac volume, Haugh unit (HU), yolk color, albumen and yolk pH, yolk index and FTIR analysis were determined at weekly basis for 6 weeks. Albumen and yolk pH increased with storage. But it is significantly lower in mineral coated eggs (p < 0.05). Whereas HU and yolk index decreased during storage in wax coated and non-coated eggs (p < 0.05). Grades of non-coated, "boomi" wax coated and "dawul kurundu" wax coated eggs were changed from AA to B within 4 weeks whereas in mineral oil coated eggs (MO) remain in AA. Weight loss of wax coated eggs were significantly higher compared to MOs (p < 0.05). FTIR analysis revels that the no chemical changes occur due to the wax. Increase of air sac was higher in noncoated eggs (5.39 ± 0.3 mm) after 42 days compared to "boomi" wax (4.59 ± 0.2 mm), "dawul kurundu" wax (3.27 ± 0.3 mm) and mineral oil (1.19 ± 0.3 mm) coated eggs. Thus, study showed that these two plant waxes had better qualities than non-coated eggs but less than the MOs.