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An Evaluation of “Heat Damage” and Fungi in Relation to Sunflower Seed Quality. J. A. Robertson, Research chemist, USDA, ARS, Richard B. Russell Agricultural Research Center, P.O. Box 5677, Athens, GA 30613; R. G. Roberts(2), and G. W. Chapman, Jr.(3). (2)(3)Plant pathologist, and research chemist, respectively, USDA, ARS, Richard B. Russell Agricultural Research Center, P.O. Box 5677, Athens, GA 30613. Phytopathology 75:142-145. Accepted for publication 9 August 1984. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1985. DOI: 10.1094/Phyto-75-142.

Thirteen samples of sunflower oilseed graded No. 1, and 21 samples of Sample grade (SG) were analyzed for percent moisture, percent free fatty acids (FFA), fungal colony-forming units per gram of seed (cfu), percent seed yielding fungi, the kinds of fungi present, and total isolates of Aspergillus. The relationship of “heat damage” (visible darkening of the meat of sliced seeds that may be caused by the heat applied to dry the seeds or by postharvest fungal invasion during storage), an important grading character, to these other parameters was studied by using correlation and linear regression analyses. Several samples of No. 1 seed had little or no heat damage but unacceptably high FFA values. Almost half of the Sample grade samples produced oil with acceptably low levels of FFA but had high heat damage scores. Apparently, overheating of sunflower seed during drying can cause heat damage without producing high FFA levels. Correlation and linear regression analyses failed to reveal adequate relationships between heat damage and the other quality parameters that were studied. For No. 1 seed, percent FFA showed a positive correlation with percent seed yielding fungi. For SG seed, percent FFA correlated positively with percent seed yielding fungi and percent moisture, percent seed yielding fungi and cfu, and cfu and percent recovery of Aspergillus. Heat damage has been incorporated into the new Federal standards for sunflower seed, but the results of this study indicate that heat damage scores in the traditional sense do not always accurately reflect sunflower seed and oil quality as determined by chemical analyses. It is suggested that a more quantitative evaluation, such as percent FFA, be used in conjunction with the more traditional criteria for grading sunflower oilseed.

Additional keywords: Helianthus annuus.