Improving efficiency in boiled egg production

Freshpak is the UK’s largest boiler of eggs, getting through 250 million each year. The company supplies the vast majority of egg mayonnaise for sandwich fillers in the UK as well as whole boiled eggs for salads etc. Seeking a way to improve the productivity of their plant – just a 1% increase in mass recovered would be worth £100,000 each year – Freshpak approached the University of Leicester.

We swiftly identified the need to carry out an ‘egg audit’ at every stage of the cooking process. By studying the mechanical properties of eggs during boiling and cooling we determined which aspects of this affect the efficiency of the peeling process. This enabled us to identify the optimal cooking conditions to enable quick, clean peeling.

We swiftly identified the need to carry out an ‘egg audit’ at every stage of the cooking process. By studying the mechanical properties of eggs during boiling and cooling we determined which aspects of this affect the efficiency of the peeling process. This enabled us to identify the optimal cooking conditions to enable quick, clean peeling.

The project was funded initially through a consultancy project in which six undergraduate students from the Departments of Chemistry and Mathematics gained valuable industry experience. The chemists examined different aspects of the cooking, cooling and peeling process while the mathematicians analysed trends in large data sets to look for seasonal fluctuations in egg yield and quality. In addition, Knowledge Transfer Partnership funding from InnovateUK was used to place a research associate in the Freshpak factory.

The first challenge to overcome was the absence of any standard way of quantifying the peelability of a boiled egg. It was something that no-one had actually tried to measure before – but without such data there could be no way of judging the success of any intervention and making direct comparisons.

A range of processes were developed to remove the shell in a standard way which enabled the students to then quantify and compare the reproducibility of the tests. Within two weeks we were confident that we had produced the first quantifiable measure of ‘egg peelability’ – which has the potential to become an industry standard test.

Once this had been developed the researchers were able to investigate the effect of pre-treatment, cooking and cooling conditions on peelability, quantifying changes in egg quality and developing novel preservation methods. Small-scale tests on a few hundred eggs suggest that optimising the process could be worth an annual £2 million to Freshpak.

Additionally, investment in new equipment for testing of soft solids, based on the success of this project, has led on directly to two other food-based research projects. The potential applications and benefits of what started as a very prosaic question – how can we peel eggs more efficiently? – are enormous.