calculation of haugh unit of egg
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The Haugh unit is a measure of egg protein quality based on the height of the egg white when the egg is broken onto a flat surface, adjusted for egg weight. The higher the Haugh unit number, the better the egg quality, with numbers ranging from excellent quality over 90 to unacceptable below 50. To calculate the Haugh unit, the height of the thick egg white is measured with a micrometer and correlated to the weight of the egg using a formula. The Haugh unit rating provides an important industry measure of egg freshness and quality.
calculation of haugh unit of egg
- 1. Aim Calculation of Haugh’s unit of egg The Haugh unit is a measure of egg protein quality based on the height of its egg white (albumen). This is the logarithm of the height of the inner thick albumen adjusted for egg weight (Haugh, 1937). The test was introduced by Raymond Haugh in 1937 and is an important industry measure of egg quality next to other measures such as shell thickness and strength. On storage the integrity of albumin structure is lost; as a result albumin spreads thinly when broken on a cooking surface. Egg weight, albumen and yolk height, Haugh unit, albumen and yolk indices decreased with increase in storage time while albumen and yolk width increased. Egg length and width were not affected by storage time and method. The quality of egg albumin is measured by measuring Albumin index, Haugh’s unit The higher value of HU corresponds to better quality of eggs if other characteristics are good. H.U varies with storage – 82 at farm; 77 for whole sale; 60 for retail. For an egg of poor quality H.U ranges from 36-60 while for a egg of good quality HU is 72. Instrument required 1. Tripod micrometer 2. weighing balance Procedure 1. Take a sample (egg) 2. egg is weighed 3. after that egg is broken onto a flat surface (breakout method), and a micrometer used to determine the height of the thick albumen (egg white) that immediately surrounds the yolk. 4. The height, correlated with the weight, determines the Haugh unit, or HU, rating. The higher the number, the better the quality of the egg (fresher, higher quality eggs have thicker whites). Although the measurement determines the protein content and freshness of the egg, it does not measure other important nutrient contents such as the micronutrient or vitamins present in the egg. Formula The formula for calculating the Haugh unit is: Where: • HU = Haugh unit • h = observed height of the albumen in millimeters • w = weight of egg in grams • H.U is the function of height of thick albumin and weight of the egg. Measurement of height of thick albumin is done by using micrometer.
- 2. Haugh Unit rating Quality of eggs 90 and above Excellent 80 - 89 Very good 70 - 79 Acceptable 65 - 69 Fair 60 - 64 Consumer resistance point* 55 - 59 Poor 50 and below Unacceptable