Carbonisation and morphological changes in modern dehusked and husked Triticum dicoccum and Triticum aestivum grains

Modern Triticum dicoccum and Triticum aestivum grains, with and without glumes, were subjected to experimental carbonisation under anoxic conditions. Experimental variables were the presence or absence of glumes, temperature, exposure time and heating rate. The maximum temperature was 600 degrees C, the time of exposure was 60 min and the heating rate between 1 and 100 degrees C/min. Length, width, area, mass loss and reflectance of uncarbonised and carbonised grains were measured as a function of the variables. The main effects of charring are an increase in width, decrease in length and formation of protrusions. Reflectance measurements allow for the determination of the temperature at which carbonisation occurred. The occurrence of protrusions on the pericarp, longitudinal imprints in the pericarp and concave flanks are observed and discussed. The calculated shape factor 100L/W is a useful tool for distinguishing between T. dicoccum and T. aestivum grains in samples that contain at least thirty specimens, but for single grains this method is problematic.