Effect of High Temperature Treatments on Growth of Penicillium spp. and their Development on ‘Valencia’ Oranges
2007
Nunes, C. | Usall, J. | Manso, T. | Torres, R. | Olmo, M. | García, J. M.
The effect of time (up to 24h) and temperature (40 to 55°C) has been evaluated on in vitro growth of Penicillium digitatum and Penicillium italicum on potato dextrose agar plates or on ‘Valencia’ oranges (Citrus sinensis), previously inoculated with those pathogens. The effect of treatment on the fruit quality parameters has also been evaluated. In vitro, at 40 and 45°C, an exposure of 24h was required to inhibit subsequent mycelial growth of both pathogens during incubation for 1 week at 25°C. However, at 50 and 55°C, only 18 or 9h (6h for P. digitatum), respectively, were needed to achieve the same effect on both pathogens. Inoculated fruit was exposed for 18h at 40°C then stored for 5 days at 5°C plus 7 days at 20°C, and the experiment was repeated at three locations and over two fruit seasons. This curing regime controlled both pathogens effectively. Concerning quality changes, after cold storage (5°C), treated fruits showed a significant reduction in acid content and a slight delay on skin yellowing, on softening, and on weight losses, compared to the control fruits. These results suggest that the curing treatment could be a non-chemical alternative to the postharvest fungicides now used to control citrus green and blue moulds.
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