Browsing by Author "Cairns-Fuller, Victoria"
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Item Open Access Dynamics and control of ochratoxigenic strains of Penicillium Verrucosum and Aspergillus Ochraceus in the stored grain ecosystem(Cranfield University, 2004-04) Cairns-Fuller, Victoria; Magan, Naresh; Aldred, DavidThis study investigated the effect of interacting environmental factors on the ecophysiology of Penicillium verrucosum and Aspergillus ochraceus and ochratoxin A (OTA) production and potential for controlling growth and OTA production using essential oils and resveratrol on wheat grain. Two dimensional temporal profiles of growth and OTA production were constructed for the first time and showed that the water activity (aw) ranges required for growth and OTA production were different in vitro and on wheat grain. Growth occurred over a wider aw range than OTA production for P. verrucosum and A. ochraceus respectively regardless of the temperature tested. For example, P. verrucosum grew at 0.80-0.995 aw on wheat grain however OTA production occurred between 0.85-0.995 aw. A. ochraceus grew at 0.80-0.995 aw on wheat grain however OTA production occurred between 0.85-0.995 aw. Optimum OTA production was at intermediate aw ranges (0.93-0.98 aw) and increased with incubation period. Interestingly at sub-optimal aw there was a' stimulation in OTA production by A. ochraceus at 15-25 oC on wheat grain. Cont/d..Item Open Access Environmental factors affect efficacy of some essential oils and resveratrol to control growth and ochratoxin A production by Penicillium verrucosum and Aspergillus westerdijkiae on wheat grain.(Elsevier, 2008) Aldred, David; Cairns-Fuller, Victoria; Magan, NareshThis study determined the efficacy of three essential oils (bay, clove and cinnamon oil) and the antioxidant resveratrol (0–500 μg g−1) on the control of growth and ochratoxin A (OTA) production by Penicillium verrucosum and Aspergillus westerdijkiae (=A. ochraceus) under different water activity (aw, 0.90, 0.95, 0.995), and temperature (15, 25 °C) conditions on irradiated wheat grain. The most effective treatment (resveratrol) was then tested on natural grain. The ED50 values for growth inhibition by the oils were 200–300 μg g−1 at the aw and the temperatures tested. For resveratrol, this varied from <50 μg g−1 at 0.90–0.95 aw to >350 at 0.995aw at both temperatures. The ED50 values for the control of OTA were slightly lower than for control of growth, with approx. 200 μg g−1 required for the oils and 50–100 μg g−1 of the antioxidant, at 0.90/0.95aw and both temperatures. In wet grain (0.995aw), higher concentrations were required. For growth there were statistically significant effects of single-, two- and three-way interactions between treatments except for concentration×temperature and concentration×temperature×essential oil/antioxidant treatment. For OTA control, statistically significant treatments were aw, temperature×aw, concentration×temperature, treatment×concentration, and three-way interaction of concentration×aw×treatment for P. verrucosum and A. westerdijkiae. Subsequent studies were done with the best treatment (resveratrol, 200 μg g−1) on natural wheat grain with either P. verrucosum or A. westerdijkiae at 0.85–0.995aw and 15/25 °C over 28 days storage. This showed that the populations of the mycotoxigenic species and OTA contamination could be reduced by >60% by this treatment at the end of the storage period.