Location: Corn, Soybean and Wheat Quality ResearchTitle: Volatile organic compounds of whole grain soft winter wheat
Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2016
Publication Date: 1/31/2017
Publication URL: http://handle.nal.usda.gov/10113/5683903
Citation: Ji, T., Kang, M., Baik, B.V. 2017. Volatile organic compounds of whole grain soft winter wheat. Cereal Chemistry. 94(3):594-601. https://doi.org/10.1094/CCHEM-09-16-0243-R.
Interpretive Summary: The odor of wheat grain comes from volatile organic compounds (VOCs), and is an evident indicator of grain soundness and also affects the taste and acceptability of processed foods. The VOC composition of wheat grain determined for harvested and/or stored grain could be tainted by external factors such as fungal infection and weathering during grain development, and changed during storage after harvest, making it difficult to identify the truly intrinsic volatile organic compound composition of wheat grain. We collected wheat grains of nine soft wheat varieties at various stages of grain maturation and determined the VOC composition to establish an inherent VOC profile. General decreases in the volatile organic compound content of grain were observed as wheat grain matured. Among ten compounds detected in all nine varieties at all five stages of grain maturation, four compounds (2-methyl-1-butanol, 1-pentanol, hexanal, and 1-hexanol) were identified as the major intrinsic volatile compounds of wheat grain based on their concentrations and the known odor detection thresholds. Hexanal and 1-hexanol were determined to be the most abundant volatile compounds of wheat grain. Wheat grain infested with fungal diseases, or that stored for five months, exhibited distinctively different VOC profiles from sound grain, and could be differentiated by examining the appearance of peaks in the gas chromatography and changes in the concentrations of 1-octen-3-ol and 2-ethyl-1-hexanol, respectively.
Technical Abstract: The aroma from volatile organic compounds (VOCs) is an indicator of grain soundness and also an important quality attribute of grain foods. To identify the inherent VOCs of wheat grain unaffected by fungal infestation and other extrinsic factors, grains of nine soft wheat varieties were collected at various days post-anthesis (DPA) and analyzed for VOCs. Ten VOCs were detected in all nine varieties at all DPAs. 3-methyl-1-butanol, 2-methyl-1-butanol, 1-pentanol, hexanal, and 1-hexanol were the predominant VOCs in concentration. The VOC concentration generally decreased as grain matured from 25 to 40 DPA. Hexanal and 1-hexanol were the most abundant VOCs in five and four varieties, and ranged from 1.30 to 2.99 µg/kg and 1.21 to 5.46 µg/kg of wheat grain at 40 DPA, respectively. The VOC profiles of wheat grains infected with fungal diseases and stored for several months were uniquely different from that of sound grain.