Influence of Infrared Treatment on Mechanical Strength and Structure of Wheat Grains

The paper presents the relationship between the parameters (temperature and time) of infrared heating and wheat grain compressive resistance. Additionally, an attempt to explain the mechanism of decrease in the strength of grain under thermal processing was undertaken. Based on the results obtained, we reached the conclusion that thermal processing with infrared (IR) radiation leads to a decrease in wheat grain compressive resistance. The range of compressive resistance changes depends on the temperature and the time that the wheat grain is exposed to IR radiation: The higher the temperature and the longer the processing time, the lower grain compressive resistance. The lowest values of compressive force were recorded following the process carried out at 180 degrees C for 150 s. Changes of grain resistance are caused by damage done to their internal structure resulting from the thermal influence of infrared radiation. The damage scope is related to the temperature and processing time. There are particularly noticeable changes after processing at temperature above 150 C and time exceeding 90 s. In the course of the process carried out under these conditions (t > 150 degrees C, tau > 90 s), a phenomenon of starch gelatinization occurs. Starch begins to gelatinize from the inside of the grains, which is characteristic of the absorption and heat transfer mechanisms occurring during electromagnetic wave heating.