Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8844271 | International Journal of Food Microbiology | 2018 | 13 Pages |
Abstract
Aspergillus steynii and Aspergillus tubingensis are possibly the main ochratoxin A (OTA) producing species in Aspergillus section Circumdati and section Nigri, respectively. OTA is a potent nephrotoxic, teratogenic, embryotoxic, genotoxic, neurotoxic, carcinogenic and immunosuppressive compound being cereals the first source of OTA in the diet. In this study bioactive ethylene-vinyl alcohol copolymer (EVOH) films containing cinnamaldehyde (CINHO), linalool (LIN), isoeugenol (IEG) or citral (CIT) which are major components of some plant essential oils (EOs) were produced and tested against A. steynii and A. tubingensis growth and OTA production in partly milled maize grains. Due to the favourable safety profile, these bioactive compounds are considered in the category “GRAS”. The study was carried out under different water activity (0.96 and 0.99 aw), and temperature (24 and 32â¯Â°C) conditions. ANOVA showed that class of film, fungal species, aw and temperature and their interactions significantly affected growth rates (GR), ED50 and ED90 and the doses for total fungal growth inhibition and OTA production. The most effective EVOH films against both species were those containing CINHO. ED50, ED90 and doses for total growth and OTA inhibition were 165-405, 297-614, 333-666â¯Î¼g of EVOH-CINHO/plate (25â¯g of maize grains), respectively, depending on environmental conditions. The least efficient were EVOH-LIN films. ED50, ED90 and doses for total growth and OTA inhibition were 2800->3330, >3330 and >3330â¯Î¼g of EVOH-LIN/plate (25â¯g of maize grains), respectively. The effectiveness of the bioactive films increased with increasing doses. Overall, A. tubingensis was less sensitive to treatments than A. steynii. Depending on the species, aw and temperature affected GR and OTA production in a different way. In A. steynii cultures, optimal growth occurred at 0.96 aw and 32â¯Â°C while optimal OTA production happened at 0.99 aw and 32â¯Â°C. In A. tubingensis cultures optimal growth happened at 0.99 aw and 32â¯Â°C, although the best conditions for OTA production were 0.99 aw and 24â¯Â°C. Thus, these species can be very competitive in warm climates and storage conditions. The EVOH-CINHO films followed by EVOH-IEG and EVOH-CIT films, designed in this study and applied in vapour phase, can be potent antifungal agents against A. steynii and A. tubingensis and strong inhibitors of OTA biosynthesis in maize grains at very low doses. This is the first study on the impact that interacting environmental conditions and bioactive films containing individual components of EOs have on the growth of these ochratoxigenic fungi and on OTA production in maize grains.
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Authors
Andrea Tarazona, José V. Gómez, Rafael Gavara, Rufino Mateo-Castro, José V. Gimeno-Adelantado, Misericordia Jiménez, Eva M. Mateo,