Effect of Benzoic and Sorbic Acids on Mycotoxins Inhibition in Edible Broad Bean Seeds

Abstract

Natural infected broad bean seeds were collected from Noubaria region during the season of 2012-2013. The isolated and purified fungi from these seeds were identified as: Alternaria alternata, Penicilliun citrinum and Aspergillus flavus. Occurrencefrequencies of the isolated fungi were 75.76, 15.16 and 9.08%, respectively. Toxin production potentials of Alternaria alternata and P. citrinum isolates, as estimated by Plug Agar method, were 231.00 and 337.00 µ.g/g, respectively., whereas, A.flavus isolate was unable to produce aflatoxins. Sorbic and benzoic acids were proved to be more effective in reducing fungal growth of A. alternata and P. citrinum than metalaxyl and ridomyl fungicides. A. alternata was less sensitive to sorbic acid than benzoic acid. All the tested treatments, at their MICs, significantly reduced growth of A. alternata growth and alternariol (AOH) production; however, higher efficiency ratio (99.860%) was realized by benzoic acid. Similar inhibition of growth and citrinin (CTN) production was induced by P. citrinum. Metalaxyl was less efficient in inhibiting AOH and CTN than the other tested treatments. Soaking seeds in water significantly raise the efficiency of mycotoxins production in all the tested seed treatments. Moreover, efficiency of benzoic and sorbic acids in reducing AOH and CTN production was higher during soaking process. Seeds inoculated with the tested pathogens, then treated with sorbic or benzoic acid appeared healthy with normal color, texture and morphology.