EFFECT OF NATURAL VANILLIN ON GERMINATION TIME AND RADIAL GROWTH OF MOLDS IN FRUIT-BASED AGAR SYSTEMS

The inhibitory effects of various concentrations of natural vanillin o n the growth of Aspergillus flavus, A. niger, A. ochraceus and A. para siticus in laboratory media and five fruit (apple, banana, mango, papa ya and pineapple)-based agars at pH 3.5 and wafer activity (a(w)) 0.98 were studied. The most resistant mould to the conditions studied was A. niger, followed by A. parasiticus, A. flavus and A. ochraceus. For each mould the increase in vanillin concentration and the type of frui t used in agar preparation significantly (P < 0.05) affected the radia l growth rate. The vanillin inhibitory concentrations were in general lower than 2000 ppm. The inoculated moulds grew faster and in higher v anillin concentrations on mango and banana fruit-based agars. The lowe r inhibitory effect of vanillin in mango and banana agar was attribute d at least partially to their fat and/or protein content.