CHANGE OF THE ACID NUMBER OF WHEAT GRAIN FAT WHILE STORED IN LABORATORY CONDITIONS

Abstract

To establish the deadline for freshness and shelf life of wheat during long-term storage, the indicator is considered — acid number of fat (ANF) mg KOH per gram of fat in the stored grain sample. To study the nature of the change of this indicator from temperature and relative humidity of the air, the present studies were performed. Samples of grain, harvest 2017, were placed in a desiccator over salt solutions, which were used to set a certain relative air humidity above the surface of the solution in the range from 35% to 75%. In each desiccator were placed two samples of wheat grain III and IV class weighing about 500 g each. The grain layer in the desiccators was 70–80 mm. To monitor the state of the samples, the Logger 100 TV temperature and relative humidity recorders were placed inside the grain layer with a recording interval of readings after 2 hours. Periodically sampled grain from each desiccator for the determination of ANF and humidity. Acid number of fat was determined by the accepted standard method.

The uniformity of humidity values in the desiccators 60% and 75% occurred after two months of storage. For a relative humidity of 35%, 44% arrived after approximately one month of storage. Some fluctuations in relative humidity values are associated with temperature changes at the storage location (laboratory room), as well as with the opening of a desiccator when taking grain samples to determine humidity and ANF. Fluctuations in relative humidity did not exceed 3%. Significant changes (growth) of ANF were observed in the fourth to fifth month of storage the samples at temperatures above 20 °C, at a storage temperature of 10 °C, practically no significant changes in ANF were observed during 9 months of storage.