Urease enzyme activity

Urease enzyme activity is the main criterion for the quality and effectiveness of soybean processing (to improve its nutritional quality and reduce the anti-nutritional factors).

The effect of heat treatment on the nutritional properties of soybean was discovered by American biochemists Osborne and Mendel in 1917. 1944, American scientists Casky and Knapp developed a method to detect the quality of soybean meal (SBM). This method was based on measuring the urease activity in soybeans.

Based on these studies, the major professional chemists associations (AOCS American Oil Chemists’ Society, 2011) and (AACC American Association of Cereal Chemists, 1995) have developed and published a simple method to assess soy products.

This method has become the standard one.

It has become generally recognized that the reduction of the activity of urease in soybean meal (or its pH) from 0.05 to 0.2 – is sufficient for use in feed for non-ruminants.

Changing ΔрН to less than 0.05 means that the heat treatment was excessive and there is a danger of denaturation of proteins in the product.

Changing ΔрН to a level greater than 0.2 means that the heat treatment was insufficient and the level of anti-nutrients is not reduced enough.

The above statements have been questioned by Dale and co-workers in 1987.

They proved that the use of ΔрН = 0,05 as the criterion of excessive heat treatment has no grounds. Their research proved that the value of ΔрН= 0,00 does not necessarily mean that soybean meal has been subjected to excessive heat treatment, but simply shows zero urease activity.

The source of information:

“NEW INSIGHTS ON THE UREASE ACTIVITY RANGE FOR SOYBEAN MEAL”. Nelson Ruiz, PhD. Nelson Ruiz Nutrition, LLC USA