Efficacy of several organic acids against molds

The efficacy of several organic acids against growth of molds typically fou nd in animal feed was determined. A plate assay was used in which paper dis ks soaked in a spore solution were placed on the surface of agar plates con taining increasing concentrations of the respective organic acid. Mold grow th radiated from the disks, and the radius was considered indicative of the degree of inhibition as compared to a control. The efficacy of each of the organic acids against the various molds varied substantially. Valeric acid , propionic acid, and butyric acid displayed the highest efficacy against a ll molds with the effective concentrations ranging from 0.05 to 0.25%. Othe r acids, including acetic acid, lactic acid, and benzoic acid, required con centrations of 10 lb/ton or more for effective mold inhibition. Susceptibil ity of molds to inhibition by organic acids was in the order Fusarium spp. > Aspergillus spp. > Penicillium spp., with Fusarium spp. being the most su sceptible mold.