Haugh unit
The Haugh unit is a
An egg is
Formula
The formula for calculating the Haugh unit is:[citation needed]
Where:
- HU = Haugh unit
- h = observed height of the albumen in millimeters
- w = weight of egg in grams
Haugh Index :
AA : 72 or more
A : 71 - 60
B : 59 - 31
C : 30 or less
Below are the USDA's terms describing egg white and its corresponding Haugh unit:
(a) Clear. A white that is free from discolorations or from any foreign bodies floating in it. (Prominent chalazas should not be confused with foreign bodies such as spots or blood clots.)
(b) Firm (AA quality). A white that is sufficiently thick or viscous to prevent the yolk outline from being more than slightly defined or indistinctly indicated when the egg is twirled. With respect to a broken-out egg, a firm white has a Haugh unit value of 72 or higher when measured at a temperature between 45F and 60F.
(c) Reasonably firm (A quality). A white that is somewhat less thick or viscous than a firm white. A reasonably firm white permits the yolk to approach the shell more closely which results in a fairly well defined yolk outline when the egg is twirled. With respect to a broken-out egg, a reasonably firm white has a Haugh unit value of 60 up to, but not including, 72 when measured at a temperature between 45F and 60F.
(d) Weak and watery (B quality). A white that is weak, thin, and generally lacking in viscosity. A weak and watery white permits the yolk to approach the shell closely, thus causing the yolk outline to appear plainly visible and dark when the egg is twirled. With respect to a broken-out egg, a weak and watery white has a Haugh unit value lower than 60 when measured at a temperature between 45F and 60F.
- Excerpt from United States Department of Agriculture (USDA)
United States Standards, Grades, and Weight Classes for Shell Eggs, AMS 56, Effective July 20, 2000
References
- ^ Time magazine. Archived from the originalon July 9, 2010. Retrieved 2010-07-11.