Location: Grain Quality and Structure Research2011 Annual Report
1a. Objectives (from AD-416)
Determine the chemical, physical and sensory attributes in "off" odor sorghum grain for the development of a standard reference sample.
1b. Approach (from AD-416)
GIPSA and ARS are involved in the independent research of measuring grain quality characteristics. The parties agree that meeting the objectives of this project will serve to strengthen and enhance the research programs of both entities by furthering the understanding of improved tools and techniques to determine unacceptable odors in grain sorghum and potentially other grains. It is intention of the parties to this Agreement that the research work shall affirm their mutual interest in cooperative research programs and exchanges and shall be for their mutual benefit and the benefit of the people of the United States. GIPSA request ARS to conduct research on the impact of “off” odor in sorghum on the chemical, physical and sensory quality of sorghum grain. GIPSA agrees to award ARS resources to conduct the above research and provide samples with different degrees of off odors. ARS agrees to study physical and chemical variations between molded and healthy sorghum grain. ARS will provide a sub-award to Kansas State University to complete supplemental work to obtain chemical and sensory traits. The project will be conducted as collaboration between GIPSA-ARS. A major criterion for evaluating sorghum grain quality is odor. Both domestic and international customers are very adept in their ability to detect “off odor” in sorghum grain. If an “off odor” exists a red flag immediately is raised and the quality of the sorghum is suspect. ARS would benefit by collaborating with GIPSA on this project to determine a means to evaluate for “off odor” and the inherent chemical components that comprise the “off odor(s)”. The collaboration may lead to the development of a sensory panel for GIPSA that may be used in assessing sorghum grain quality using sensory and chemical analyses.
3. Progress Report
Some volatile compounds present in musty sorghum can be linked to musty odor notes, and even differentiated into two groups: “dry” and “wet” musty odor. Musty sorghum with “wet” odor notes seemed to have other off-odor notes stated as earthy/damp or moldy. The presence of these odor notes seemed to indicate a higher grade of deterioration in the grain when compared with the “dry” musty grain samples. The presence of some aromatic compounds (such as pyrazines and methoxybenzenes), in these samples was absent in the “musty, dry” sorghum grain samples. These differences between “dry” musty and “wet” musty sorghum grain, were corroborated by the sensory analysis results. A major finding, however, is that “musty” is musty regardless of whether it is subdivided into wet or dry musty. Both result in a clear sensory description call “musty”. Some references/standards were elaborated using the instrumental aromatic data and the sensory descriptive analysis as principal tools. These references will allow the USDA inspectors to unify and increase consistency in the sensory analysis used to grade sorghum grain. With these references, new criteria can be used for grading grain, if the secondary odor notes (“dry” or “wet” musty odor) are considered. Following the panelist recommendations, clean grain was used as the basis to prepare the references. Geosmin (0.1 ug/kg) and 1,2-dimethoxybenzene (100 ug/kg), and 3-octanone (100 ug/kg) and 1,2,4-trimethoxybenzene (100 ug/kg), were the chemical compounds chosen to reproduce the musty-wet and musty-dry odor notes respectively. Progress of project was monitored via email.