|Author: ||S.M. El Neshawy|
|Keywords: ||postharvest handling system, sweet potato, Ipomoea batatas, UV C exposure, soft rot, Rhizopus stolonifer|
Soft rot caused by Rhizopus stolonifer on sweet potatoes is a remarkable phenomenon in Egypt during postharvest handling.
In the presence of moisture content, sugar-like fungi as R. stolonifer attack the tuber tissues, which ultimately cause full deterioration.
The whole process-chain for exporting sweet potato native cultivar 'Abees' to the English market, include immediate curing after harvest, trimming, washing, packing, stalking, transportation and sea or air shipping.
However, to reduce further postharvest rots, other treatments were tested.
Exposure of tubers to UV-C (254 nm) at 20 cm distance for 1, 2, and 3 h, achieved marked reduction of the microbial load on tuber surfaces and subsequently reduced tuber soft rot to almost 0% and maintained tuber characteristics after 3 months of cold storage.
The ability of UV-C light to heal skin texture, induce PAL enzyme activity in tuber tissue, and slightly increase peroxidase and polyphenol oxidase activities was observed.
As the exposure time to UV-C light increased, a higher quantity of phenols and a slight decrease of sugar content in tuber tissues were recorded.
Quality assessment of sweet potato tubers through the whole export channel up to the final destination was performed, including tolerance to major and minor defects on sweet potatoes due to infection by R. stolonifer. The overall impact was a significant reduction in postharvest losses and increase in the export capacity.
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