- N Mathaba1 , MH Schoeman1 , FA Botha1 and FJ Kruger2
-
1Agricultural Research Council - Institute for Tropical and Subtropical Crops, Private Bag X 11208, Nelspruit 1200, RSA
2Lowveld Postharvest Services, PO Box 4001, Nelspruit 1200, SOUTH AFRICA - 2017
A study was performed to establish whether irradiation for phytosanitary purposes will negatively influence the quality of ‘Mauritius’ litchi fruit stored under air freight simulation conditions. To do this, the fruit were placed into insect proof netting and gamma irradiated at 5 rates (0, 0.6, 0.8, 1.0 and 0.2 kGy). From the results it may be concluded that phytosanitary irradiation of correctly fumigated ‘Mauritius’ fruit of appropriate maturity should not increase the sulfur dioxide residues in the aril of the fruit. Nor should it increase fungal infections on the pericarp. It would further appear that the insect proof netting ought not to influence the quality of the fruit negatively.
Summary:
The study investigated the effect of phytosanitary gamma irradiation on sulfur dioxide residue levels and spoilage in South African ‘Mauritius’ litchi fruit stored under simulated air freight conditions.
Litchi fruit were treated with different gamma irradiation doses (0, 0.6, 0.8, 1.0, and 1.2 kGy) while packed in insect-proof netting or cartons, and quality parameters were evaluated including fungal infections, sulfur dioxide residues, total soluble solids, and total titratable acids.
Results showed that irradiation did not increase sulfur dioxide residue levels in the fruit aril; residues remained within expected safe ranges (around 5.9 to 10.9 ppm).
Fungal infections on the pericarp were not increased by irradiation or the use of insect-proof netting; notably, the lowest irradiation dose (0.6 kGy) led to significantly fewer fungal infections compared to non-irradiated fruit.
The fruit maturity at packing influenced quality but was independent of irradiation effects, and the use of insect-proof netting did not negatively impact fruit quality or sulfur dioxide residue levels.
The conclusion is that phytosanitary irradiation of properly fumigated, mature ‘Mauritius’ litchi fruit does not compromise fruit quality by increasing sulfur dioxide residues or fungal spoilage during air freight export simulation.