Chemical and fungal evaluation of graded sunflowerseed

Thirty-four samples of commercial oil-type sunflower-seed graded No. 1, 10 samples graded No. 2 and 33 samples graded Sample grade (SG) were used to study the relationship between percent heat damage, an important grading character, and percent FFA, percent color and UV absorption of extracted oil, percent germination and number and identities of fungi present. Seventy-two fungal species belonging to 28 genera were isolated. Thirty-seven fungal species in 17 genera were isolated from grade No. 1 seed; 68 species in 13 genera were isolated from grade No. 2 seed, and 68 species in 26 genera were isolated from SG seed. The genera most frequently isolated from grade No. 1 seed wereAlternaria (85.3%),Phoma (4.7%) andCladosporium (4.5%).Alternaria alternata was recovered from all No. 1 samples and comprised 75.6% of all isolates. The genera most frequently isolated from grade No. 2 seed wereAlternaria (74.5%),Eurotium (8.4%) andPhoma (7.7%). Fewer fungal species were isolated from grade No. 2 than from No. 1 seed, but a greater recovery of storage fungi was found for No. 2 seed (13.3%) than for No. 1 seed (2.5%).Alternaria (33.8%),Eurotium (33.1%) andMicroascus (8.3%) were the genera most frequently isolated from SG seed. Species of common storage fungi (Eurotium, Microascus, Penicillium andAspergillus) were recovered more frequently from SG than from Grades No. 1 and No. 2. In general, as the quality of the seed decreased from grade No. 1 to grade No. 2 to SG, there was an increase in percent heat damage, percent FFA, Lovibond color and UV absorption of extracted oil, and a decrease in percent germination. Analysis of variance of the quality characteristics data showed no significant differences between grade No. 1 and No. 2 seed except for UV 228 nm absorption. However, the quality characteristics of SG seed all differed significantly from those of grades No. 1 and No. 2 seed with the exception of percent seed yielding fungi. Correlation coefficients of the quality characteristics of SG showed a slight relationship between heat damage and percent FFA (r=0.63) and UV 228 nm absorbance (r=0.68). Although many of the SG seed were badly heat damaged, no statistical relationship was found between percent heat damage and percent seed yielding fungi or total isolates of storage fungi. The data in this study show that errors exist in grading decisions when seed are judged visually to be heat damaged.