Assessment of Heat Damage in Canadian Hard Red Spring Wheats

Abstract

A mixograph procedure is described for assessing heat damage due to hot air drying in commercial samples of Canadian hard red spring wheat. Commercial ‘before’ and ‘after’ hot air dried samples obtained from farm drier operators during the 1985 harvest could be separated into four categories of heat damage or lack thereof on the basis of mixograph curves. Composites prepared from ‘after’ drying samples rated as satisfactory or satisfactory but slightly changed showed quality characteristics almost identical to corresponding ‘before’ drying samples. Composites prepared from ‘after’ drying samples rated as seriously reduced or damaged showed detrimental changes in quality compared to corresponding ‘before’ drying samples.Individual commercial carlot samples of Canadian red spring wheat could be separated into three categories on the basis of mixograph curves including satisfactory, suspected damage and damaged. Blending studies showed that addition of commercially heat damaged wheat to undamaged wheat had significant detrimental effects upon quality characteristics at levels as low as 20%. Osborne fractionation and gel filtration studies indicated that the proportion of the insoluble glutenin protein fraction was most affected by heat damage.