Determination of volatile compounds in heat-treated straight-grade flours from normal and waxy wheats

Volatile compounds formed during heat-treatment of wheat flour influence the application of treated flour. In this study, normal and waxy hard wheat flours before and after dry-heat treatment were subjected to headspace analysis by solid-phase microextraction of volatiles followed gas chromatography mass spectrometry (GC/MS). The untreated waxy wheat flour contained higher levels of odor-active compounds than normal wheat flour including aldehydes, alcohols, furans, and ketones. Lipid oxidation appears to play major role in producing such odor compounds. Heat treatments, depending on the severity, alter the profile of volatile compounds. Low temperature (100-110 degrees C) treatments effectively eliminated cereal odor (aldehyde) and did not introduce additional odors, providing a possible way to produce low-odor flours. Heat treatments at 120 degrees C and higher temperatures elevated the content of pyrazines, furans, and sulfur-containing compounds which together gave a roasty aroma to the flours. Considering organoleptic properties, treatments of flours at 140 degrees C was superior to 160 degrees C. The waxy wheat flour was more prone to produce odor-active compounds than normal wheat flour during the same heat treatment. (C) 2017 Published by Elsevier Ltd.