Some ingredients possess intrinsic phytase activity, which varies
greatly among plant species. Corn and soybean meal contain negligible
levels of phytase activity compared to wheat, which contains
considerably higher levels of intrinsic phytase.8 The majority of
phytase activity in cereal grains is found in the aleurone layers.9
However, this may be lost when ingredients are subjected to high
temperatures, such as during the pelleting process.10 Commercially
available exogenous phytases are commonly derived from either
fungi or bacteria, such as Aspergillus niger and Escherichia coli,
6 but
can also be expressed in yeasts.11,12