Effect of storage temperature on the quality of eggs from conjugated linoleic acid-fed laying hens

Abstract

This study was designed to investigate the effects of storage temperature on the quality of eggs from conjugated linoleic acid (CLA)-fed laying hens. For 40 days laying hens (20 per group) were fed a diet containing either 0.5% maize oil (Group A, Control) or 0.5% CLA (Group B). For fatty acid analysis, three eggs were collected after the eighth day of feeding. After two days of feeding, eggs were collected and stored for 28 days at 4 ºC, 15 ºC or 24 ºC for colour quality assessment. For pH measurements, 30 eggs from each group were stored at 4 ºC or room temperature (21-24 ºC) for one, two or three weeks. Dietary CLA caused higher levels of C16:0 and C18:0 and lower levels of C16:1(n-7) and C18:1(n-9) compared to the control group. Egg yolk from Group B had higher levels of c-9, t-11 and t-10, c-12 CLA than the control group. The ratio of total saturated to unsaturated fatty acids (SFA/UFA) increased 2.4-fold in the eggs from CLA-fed hens. CLA eggs stored at 4 ºC had higher pH values in yolk and lower pH values in albumen compared to those from the control group. However, pH values of yolk or albumen in eggs stored at 21-24 ºC were similar in the control and treatment groups. Dietary CLA caused significant colour changes in yolk and albumen of the eggs stored at 4 ºC and 15 ºC. No colour changes were observed in the yolk and albumen of CLA eggs at 21-24 ºC. Results indicated that dietary CLA influenced fatty acid composition of eggs and had negative effects on the quality of eggs stored at 4 °C or 15 °C, but not at room temperature (21-24 ºC). It is suggested that CLA probably changed the permeability of the vitelline membrane during cold storage.

Hens ranked as highly feed efficient have an improved albumen quality profile and increased polyunsaturated fatty acids in the yolk1

“…In the present study, while initially the yolk score was lower (paler), but not different in the LFE group comparable with the HFE group, following storage of eggs to 28 d the LFE group had a decreased yolk color score when compared with the HFE group. During storage, the vitelline membrane of yolk is weakened and becomes permeable to minerals and water migrating from albumen into the yolk, which could contribute to the discoloration of yolk (Aydin, 2006). Other research has reported that yolk pigments are closely associated with the lipid molecules of the yolk membranes; therefore as antioxidant protection diminishes during storage, reactive oxygen species (ROS) can cause oxidative degradation of yolk lipids (Bottje et al, 2006) and its pigments (Martino et al, 2014), which could have significant effect on yolk discoloration.…”

Design of Physicochemical Properties of Eggs as a Result of Modification of the Fat Fraction of Laying Feed

“…The studies conducted by Chamruspollert and Sell found that the addition of 5% CLA to the feed resulted in a reduction in the level of monounsaturated fatty acids compared to control eggs [46]. Other researchers such as Aydin [47,48] and Raes et al have reported similar observations [49]. Additionally, a decrease in the level of C17 and C18 (oleic acid) acids was detected.…”