For her paper entitled 'Variability in estimation of egg nutritional value throughout Europe: how to control it?', Professor Ingrid Seuss-Baum of the University of Applied Sciences in Fulda, Germany, had compared many sources of data on the composition of eggs.

She found that the nutritional composition of eggs had been described using a number of different methods but that there was consensus that eggs are a good source of high-quality protein and certain amounts of vitamins and minerals. Furthermore, most of the nutrients are highly bioavailable.

The exact composition of the egg did depend on the hen's diet, she found, particularly for the lipid fraction, and this accounted for much of the variation Dr Seuss-Baum found in her survey of European food databases.

The differences in dietary allowances used as reference values in different European countries led to further confusion, she said.

Dr Seuss-Baum added that a moderate enrichment of eggs – with polyunsaturated fatty acids (PUFAs) or vitamins – in accordance with harmonised recommended dietary allowances and the regulations for nutrition and health claims could lead a reasonable concept of 'functional eggs'. However, she warned that the enrichment of foods should not risk the over-supply of nutrients.

Heat Stress and Salmonella Contamination of Eggs

Researchers from Belgium reported the results of their investigation into the effects of heat stress on the egg shell membrane and the contamination of the egg shell content with Salmonella.

From their paper, presented jointly, Kristof Mertens of Leuven University and Koen De Reu from ILVO concluded that although eight days of heat stress (above 32°C) resulted in poorer egg shell quality, membrane integrity was unaffected. They were unable to explain from this work why eggs produced under heat stress were subject to less penetration by Salmonella enterica and lower rates of contamination of the egg content by the bacteria than the control eggs.

Coating Eggs to Reduce Salmonella Penetration

Also from ILVO in Belgium, Saskia Leleu reported her work on the effects of coating eggs with a polysaccharide (chitosan) on internal egg quality and penetration of the shell by Salmonella.

Coating the eggs with chitosan increased the Haugh units and improved the yolk index score although it had no effect on egg shell contamination with Salmonella enterica (SE). However, at the highest rate applied (two per cent), eggshell penetration by SE was lower than the untreated control group, said Dr Leleu.

Gas Plasma to Decontaminate Table and Hatching Eggs

In the introduction to her paper, Frederique Pasquali from the University of Bologna, Italy, explained that gas plasma is an ionised gas that can be used as a sterilising agent under atmospheric conditions without damaging the material through heat or chemical agents. It is widely employed for the sterilisation of surgical instruments.

For table eggs, the gas plasma treatment reduced the Salmonella enteritidis (SE) load by around two logs in colony-forming units per gramme throughout the 28-day trial period. The only significant change in egg quality observed was a change in eggshell colour that was not detected by eye.

For hatching eggs, hatchability was higher for the gas plasma treatment than the control treatment (fumigation), and there were no adverse effects on culls, early chick mortality or counts of other potentially pathogenic bacteria.

Dr Pasquali concluded that this new technique is a promising alternative to existing methods that employ toxic chemicals potentially damaging to human health.

Egg Quality in Australian Eggs

Following up on a previous survey in 2003, Professor Julie Roberts reported the results of tests on a range of egg quality parameters in Australia conducted between 2007 and 2009. The main thrust of the latest work was on-farm Haugh unit measurements because the previous work had highlighted this as a problem area.

Watery whites were rarely encountered in this study and although the reason was not clear, Professor Roberts described this as a good sign. Overall, few differences were found in the quality of the shell or internal contents resulting from the state, strain of bird or egg production system although albumen height was somewhat affected by bird strain.

Albumen height and Haugh unit scores were lower when measured later in the lab than directly at the farm but this was not entirely unexpected as the values are known to decrease over time.

Compared to the previous study in 2003, egg weight was lower, egg shell colour darker, shell deformation lower and shell thickness was higher in the 2009 survey.

CT Scanning to Predict Yolk Content

From his work at Kaposvar University in Hungary, Gabor Milisits reported that computer tomography (CT) is a useful scanning method for predicting the ratio between egg yolk and egg white and certainly an improvement on previous techniques. The lowest radiation load (80kV - 40mAs) gave the best correlation.

Dr Milisits added in answer to a question that the radiation did not affect the composition of the eggs, hatchability or the health of the hatched chicks.

October 2010