What's New ? - 2025

A new study examines how standard U.S. handling methods, including washing and oiling, affect the physical quality of shell eggs stored for an exceptional period of 27 weeks. While U.S. regulations mandate washing and refrigeration, the European Union prohibits washing due to concerns over damaging the cuticle, the natural protective layer against moisture loss and microbial penetration. A study recently published in Poultry Science sought to investigate how these treatments affect egg quality under prolonged storage conditions. Researchers from the USDA National Poultry Research Center tested four treatment types on white shell eggs:

1. Unwashed eggs.
2. Washed eggs (according to USDA guidelines).
3. Washed and food-grade mineral oil-coated eggs.
4. Eggs stored refrigerated for 21 days and then washed.

Each group was stored at two different temperatures: refrigeration (4⁰C) and ambient room temperature (22⁰C). Over the course of 27 weeks, parameters including weight loss, Haugh Units (HU), yolk quality, and vitelline membrane strength were measured.
Refrigerated storage was the most significant factor in preserving egg quality. Eggs stored at 4⁰C maintained a high quality rating (Grade A) for at least 18 weeks, regardless of the treatment type (washed or unwashed). Washed and unwashed eggs stored at 22⁰C deteriorated to Grade B within just one week. After 8 weeks at room temperature, egg quality dropped below the physical measurement threshold. Coating eggs with mineral oil after washing proved highly effective. In the ambient temperature oiled group, Grade A rating was maintained for 4 weeks, and weight loss was significantly reduced (18.7% compared to approximately 50% in washed, non-oiled eggs). The oil effectively seals shell pores, replacing the natural cuticle's role in preventing CO2 and moisture loss.
The study results highlight that continuous refrigeration is the most powerful tool for extending egg shelf life.

Summary Table of Experimental Groups and Egg Quality Results