Submitted to: National Egg Quality School Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/22/2008
Publication Date: 5/19/2008
Citation: Jones, D.R. 2008. Understanding Haugh Units. 15th National Egg Quality School Proceedings,May19-22,2008,Tempe,Arizona.p.150-158.
Technical Abstract: Hand candling is the most common method of assessing interior egg quality. While this method is non-destructive, it is very subjective and takes some skill. The Haugh unit was developed in 1937 by R. Haugh and is revered as the “gold standard” for measuring interior egg quality. This objective method of interior quality determination is based on a correlation of egg weight and height of the thick albumen. USDA Agriculture Marketing Service (AMS) has published specific guidelines for Haugh unit readings and egg grades in the US market (AMS 56.210). Haugh units are determined with the aid of a micrometer, balance, and flat surface (such as an egg break-out table). A break-out table can be useful during measurements since the mirror allows the operator to determine exactly when the micrometer comes in contact with the thick albumen surface and also allows for viewing of any possible defects on the underside of the yolk. Due to advances in technology, there are now electronic methods, as well as manual, for determining Haugh units.