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.

Internal quality attributes of chicken eggs coated with Hik (Lannea coromandelica) and Mango (Mangifera indica) wax stored at room temperature

“…Moreover, HW and MW-coated eggs showed reduced weight loss (p < 0.05) compared with their NC counterparts that proving plant waxes could be attributed as an effective material to coat eggs as earlier reported [11] to reduce moisture loss.…”

“…Briefly, egg albumen was mixed for 4 min in a clean beaker using a magnet stirrer (AREC.X Heating Magnetic Stirrer, F20500554, VELP Scientifica, Usmate, Italy). Then, a drop of albumen was placed onto the surface of the ATR diamond crystal and allowed to air dry [11]. The Difference in absorbance unit with the wave number was measured.…”

“…However, it is difficult to practice such methods in rural areas in Sri Lanka due to the poor infrastructure facilities and the low income of people. Therefore, surface coating is an alternative method to preserve egg quality (i.e., internal quality parameters and weight of eggs) despite its lesser effectiveness than refrigeration but ultimately can lead to minimizing economic loss and gaining comparable high profits [11].…”

“…), and waxes (i.e., bee wax, shellac wax, paraffin wax, carnauba wax, candelilla wax etc.) [11,[15][16][17].…”

“…Therefore, many studies have attempted to investigate the use of different kinds of waxes as a coating material on fresh fruits, vegetables, and even for coating eggs to control desiccation [11,[20][21][22][23]. However, there is still room to identify and evaluate other underutilized, non-conventional waxes which are locally available, less in demand, and relatively lower in cost as potential materials for coating chicken eggs.…”