Submitted to: Journal of Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/2/2003
Publication Date: 6/1/2004
Citation: Mohamed, A., Rayas-Duarte, P., Gordon, S.H., Xu, J. 2004. Estimation of hrw wheat heat damage by dsc, capillary zone electrophoresis, photoacoustic spectroscopy and rheometry. Journal of Food Chemistry. V. 87. P.P. 195-203. Interpretive Summary: Heat damage occurs during the artificial drying of newly harvested wheat or at high storage temperature as in some countries where storage facilities are not advanced. Wheat proteins can be destroyed by kernel heat damage during storage or during the wheat milling process. Protein destruction limits their functional properties. Gluten heat damage reduces the overall quality of flour dough and results in low bread quality. The USDA considers wheat heat damage as a grading factor. Grain Inspection, Packers, and Stockyards Administration (GIPSA), a USDA agency, is looking for objective, simple, and fast methods to inspect grains. Visually checking and selecting discolored kernels is currently used to test wheat samples for heat damage. The objective of this work is to introduce one more method to test for wheat heat damage due to post harvest drying or storage. The other part of this work will be focused on spectroscopy testing of heat damaged wheat that will include statistical modeling and analysis.
Technical Abstract: The effect of heat damage was estimated using Hard Red Winter (HRW) wheat varieties grown in Oklahoma. The testing was done on wheat kernels, flour, and isolated starch. Whole-wheat kernels were analyzed by Photoacoustic Spectroscopy (PAS). Flour was analyzed by DSC, Capillary Electrophoresis (CE), and rheometry, while starch was analyzed by DSC. The DSC data showed little difference in the temperatures of the starch gelatinization. The H values showed increase at 50ºC storage temperature. The PAS data of the three cultivars showed different sensitivity to heat. Jagger cultivar pericarp is possibly five times more heat resistant than the pericarp of the other two varieties. The CE data showed that 2137 cultivar was more affected by the 60 days and 50ºC treatment than the other two cultivars. The change was noticeable on the gliadin and the glutenin profiles, where some peaks disappeared after treatment and others were reduced in size. The non-linear steady shearing showed that all cultivars heat-treated flours had lower viscosity, which indicate lower baking quality. The viscoelastic properties of Jagger untreated suspension sample showed stronger gluten. The linear and non-linear viscoelastic behavior of Jagger cultivar was less altered by heat treatment when compared to the other cultivars.