Effect of Egg Washing on the Cuticle Quality of Brown and White Table Eggs

Abstract

Egg washing is currently not permitted within the European Union, with few exceptions. This is mainly because there are concerns that cuticle damage could occur during or after the washing process, as a result of a suboptimal operation. In this study, the cuticle coverage levels of 400 washed or unwashed eggs, derived from either a brown or a white egg-laying flock at the end of lay, were compared. The eggs from older hens inherently have poorer cuticle coverage and as a result arguably constitute a greater risk to consumer safety if they are then washed. Thus, the effects of the washing procedure used in this study on cuticle quality were tested under the worst-case scenario. A standard Swedish egg washing process was used. The cuticle coverage of the eggs was assessed by a colorimeter by quantifying the color difference before and after staining with Tartrazine and Green S. The cuticle of an additional 30 eggs from each of the four groups was then visually assessed by scanning electron microscopy. The staining characteristics of the cuticle varied greatly within each group of eggs and showed that the washing process did not lead to cuticle damage. Scanning electron microscopy confirmed that there was no irreversible damage to the cuticle of the washed eggs and that it was not possible to correctly assign the treatment (washed or not) based on a visual assessment. In conclusion, no evidence could be found to suggest that the washing procedure used in this investigation irreversibly changed the quality of the cuticle.

Scientific Opinion on the public health risks of table eggs due to deterioration and development of pathogens

“…The same difference was highlighted for storage at 5 °C vs. 22 °C, regardless of the duration of incubation (14, 24 and 42 days) (Aygun and Sert, 2013). The pH increase recorded by Leleu et al (2011) at ambient temperature was lower, i.e. an increase of around 0.1 pH unit after the first two weeks of storage; the pH was unchanged for longer incubation periods, i.e.…”

“…These authors showed that this parameter was unaffected at 5 °C up to 42 days of storage. In the study of Leleu et al (2011), a decrease of around 16 % was observed after the first two weeks of storage at ambient temperature. Further incubation (up to five weeks) did not induce a further decrease.…”

“…The yolk index, widely used to express the spherical nature and thus the quality of the yolk, decreases with time throughout the incubation period (up to 42 days) at 22 °C, while its value remains stable at 5 °C (Aygun and Sert, 2013). According to Leleu et al (2011), the decrease in the yolk index was a function of time at ambient temperature. A final 15 % decrease was observed after five weeks incubation.…”

“…According to Leleu et al (2011), the increase in the height of the air chamber is obvious from the first week of storage at ambient temperature. This phenomenon continues for up to five weeks, leading to a final three-fold increase in volume.…”

“…However, this process is greatly accelerated if the temperature increases and/or the relative humidity decreases: the percentage of egg weight loss is around three to four times higher at 25 °C than at 10 °C (Sauveur, 1988) or at 22 °C than at 5 °C (Aygun and Sert, 2013), other things being equal. According to Leleu et al (2011), there is a strong influence of the length of storage on the percentage of egg weight loss at ambient temperature. A loss of around 5 % was observed at the end of a storage period of 5 weeks at ambient temperature.…”