Effect of high temperature treatments on growth of Penicillium spp. and their developent on Valencia oranges.

摘要

Effects of heating for <=24 h at 40-55 degrees C were investigated on growth of Penicillium digitatum and P. italicum on potato dextrose agar plates or on inoculated Valencia oranges (Citrus sinensis). The impact of treatments on fruit quality parameters was also evaluated. In vitro, at 40 and 45 degrees C, a heating time of 24h was required to inhibit subsequent mycelial growth of both pathogens during incubation for 1 wk at 25 degrees C. However, at 50 and 55 degrees C, only 18 or 9 h (6 h for P. digitatum), respectively, were needed to achieve the same effect on both pathogens. Inoculated fruit was treated for 18 h at 40 degrees C, then stored for 5 days at 5 degrees C plus 7 days at 20 degrees C; the experiment was repeated at 3 locations and over 2 fruit seasons. This temp. regime controlled both pathogens effectively. After cold storage (5 degrees C), treated fruits showed a significant reduction in acid content and slight delays in skin yellowing, softening and wt. loss, compared to control fruits. Results suggest that the heating treatment could represent a non-chemical alternative to the postharvest fungicides now used to control citrus green and blue moulds.