3. Results and discussion
3.1. Dextranases available in the US
Most commercial dextranases currently available in the US are produced from a fungal source: C. gracile or C. erraticum, and have generally recognized as safe (GRAS) status. The US Food and Drug Administration does not approve of dextranases from Penicillium bacterial sources which are sold overseas. Dextranases from Chaetomium have been shown to hydrolyze faster than than dextranases from Penicillium and Bacillus sources [19]. One of the greatest sources of confusion for factory staff about dextranases is that it is not possible to compare the activities (or strengths) of commercial dextranases directly because each dextranase vendor uses a different method to measure activity. For example, units of dextranase activity can be u/g, Du/g, U/ml and Du/ml. This is further exascerbated by the fact that the dextranase market is very dynamic and dextranase activities and prices can change regularly. Consequently, there is an urgent need for a uniform method to measure dextranase activities at the factory. For this reason, a simple titration method to determine the relative activity of dextranases was identified [14] and modified for easy use at the factory [15]. The method does not need any sophisticated equipment such as a spectrophotometer and there is no need for standards and a standard curve. Having an easy-to-use method to measure activity will allow factory staff to compare commercial dextranases and make more informed decisions on which dextranase to use; the stability of the dextranases stored across the grinding season can also be monitored.