CHLORINE INACTIVATION OF FUNGAL SPORES ON CEREAL-GRAINS

Although 0.4% chlorine for 2 min has been recommended for surface disi nfection of food samples before direct plating for fungal enumeration, this procedure may not be adequate for highly contaminated products. The effectiveness of a range of chlorine solutions was investigated us ing barley samples artificially contaminated with four different conce ntrations of Aspergillus flavus, A. niger, A. ochraceus, Eurotium repe ns, Penicillium brevicompactum P. chrysogenum and Cladosporium cladosp orioides. At initial contamination levels greater than 10(4)/g, 0.4% c hlorine did not inactivate sufficient spores to produce less than 20% contamination. Of the test fungi, ascospores of E. repens were the mos t resistant to chlorine inactivation, whereas the conidia of C. clados porioides were the most sensitive. Rinsing the samples with 70% ethano l improved the effectiveness of the recommended surface disinfection p rocedure. However, some ethanol appears to permeate into the grains an d may inactivate sensitive internal fungi, although a minimal effect o nly was observed on wheat infected with Alternaria. (C) 1997 Elsevier Science B.V.