Falling time of cereals and their products is an index of the enzyme alfa amylase activity, which in correctly ripen and collected under dry conditions grains occurs in negligible amounts. However under unfavourable atmospheric conditions the moisture level of cereals is higher than 15% the enzyme becomes activated. In consequence it causes dramatic damage to starch kernels. Dough prepared from such flour has unfavourable physico-chemical properties not granting good quality bread baking. Therefore knowledge of the degree of impairment of cereals and their products allows their correct qualification and the following way of their use, for instance: for feeding purposes, for making mixtures, that is impaired cereals with those not damaged by alfa amylase or working out individual technological processes with „improvers“ to avoid unexpected losses.