Fungal (mold) contamination is an important indicator of low quality raw pr
oduct in the processing tomato industry. A quantitative lectin assay was de
veloped that was less expensive, faster, and more precise than the industry
standard Howard mold count. This assay, based on a fluorescent-labeled lec
tin isolated from wheat germ, had a selective affinity for the chitin in fu
ngal cell walls. Assay values were correlated with mold contamination for 4
fungal species: Alternaria alternata (r(2) = 0.91), Cladosporium herbarum
(r(2) = 0.75), Fusarium oxysporum (r(2) = 0.97), and Stemphylium botryosum
(r(2) = 0.99). Combining all 3 species, the lectin assay had a strong corre
lation (r(2) = 0.76) with a linearized Howard mold count.