Effects of caraway and juniper essential oils on aflatoxigenic fungi growth and aflatoxins secretion in polenta

Abstract

Inhibitory activity of caraway and juniper essential oils was tested against two aflatoxigenic strains (Aspergillus flavus-four isolates and Aspergillus parasiticus-one isolate) using the method of agar plates. A. flavus IKBT and A. flavus IKB isolated from corn flour, A. flavus IKT isolated from peanuts, and A. flavus IKK isolated from flint corn. A. parasiticus CBS 260.67 was obtained from the Centralbureau voor Schimmelcultures (CBS, Utrecht, The Netherlands). The inhibitory effect of essential oils on aflatoxins secretion by A. flavus (isolated from maize flour) was examined in the polenta. Growth of all fungi were completely inhibited at caraway essential oil concentration of 4.5 mu l/g. At this concentration, aflatoxin secretion was completely inhibited in polenta. Juniper essential oil particularly inhibited growth of examined fungi at the applied concentration of 35 mu l/g (from 42.4% to 79.7%). At concentration of 50.0 mu l/g, this oil completely inhibited aflatoxin secretion in polenta. Practical applications The obtained results show that caraway essential oil had significantly better inhibitory effects against A. flavus, A. parasiticus, and aflatoxins production than juniper essential oil, in vitro and in polenta. Future research should point to the possible application of this oil in different types of food and the choice of an efficient method: adding them directly to the product, surface coating of the products, dispersing, applying them in the atmosphere of the package, coating the inner side of the packaging, applying in edible films, or in the form of nanocapsules. In the case of polenta, essential oils can be applied in the packaging atmosphere, by coating the inside of the package, or adding them directly to the polenta.