| Fungal (mold) contamination is an important indicator of low quality raw product or unsanitary processing conditions in the food industry. A quantitative lectin assay was developed that was less expensive, faster, and more precise than the industry standard Howard mold count. This assay, based on a fluorescent-labeled lectin isolated from wheat germ, has a selective affinity for the chitin in fungal cell walls. Assay values had high linear correlations (from r 2 = .72 to r2 = .99) with fungal biomass for ten fungal species of greatest importance to the California processing tomato industry.;One hundred raw tomato juice samples with natural mold infections were collected, as part of the normal California processing tomato inspection program, from commercial processing tomato loads. The raw juice samples were sent to four processor quality control laboratories, where an industry standard Howard mold count was conducted on blind triplicates of each of the samples. The lectin assay was also conducted on blind replicates of the raw juice samples. The correlation between the lectin assay and the Howard mold count (r = .85) was as strong as the correlation between the Howard mold counts for two facilities. The assay had significantly better (α = .01) precision than the Howard mold count, with an average coefficient of variation of 8%, compared with 38% for the Howard mold count. The assay is objective, can be conducted in under six minutes, and has the potential to replace mold testing in both raw and processed products. |
