Raw soybeans contain the anti-trypsin inhibitor, urease and also lipoxygenase enzymes. During the microwave roasting process both are being changed to obtained soybeans that are biological available and also nice tasting for the human and monogastric animals. To make sure that the process are completed we must test the roasted soybeans at the end before it can be used as edible food or animal feed.

Several tests are routinely done to assess the adequacy of heat treatment during soybean processing. A simple one that is widely used in crushing plants and feed mills is the urease test. The presence of active trypsin inhibitor is often indirectly determined by measuring the activity of urease enzyme present in soy. Soybean contains urease, an enzyme that converts urea to ammonia. Although urease in soybeans is not nutritionally significant to fish species, it is inactivated at a temperature similar to that required for destruction of trypsin inhibitors. The urease test is much cheaper and easier than the trypsin inhibitor assay. 

In the urease test, a sample of roasted soybean meal is obtained. Due to the breakdown of the urease after roasting the resulting ammonia increases pH, which can be measured with a pH meter or an indicator dye such as phenol red. The official method has been published by the American Oil Chemists Society. Soybean meals with a urease value above 0.3 units of pH rise are considered under toasted. Meals below 0.02 units of pH rise may be over processed or still of good quality. In the case of the phenol red test the roasted soybean meal will stay red in case of insufficient roasting whilst the proper or sufficient roasted soybeans will be white.

The phenol red method of testing the roasted soybeans are the simplest and mostly accepted in industry to test for changing the anti-trypsin inhibitor and also the lipoxygenase enzymes that normally creating the beany taste in soybeans.

It is therefore important to make sure that the raw soybeans must be roasted properly at the right temperature.

Testing:

We run the soyabean by different microwave heating power include 1700w, 2550w and 3400w and the processing time is 60s, 90s, 120s, 150s, 180s and 210s.  We analyze the urease and trypsin inhibitor statistics.

Urease---One Gram

Trypsin inhibitor— One Gram 

Contact with MAX Industrial Microwave for heating and roasting soybean.