Effects of gamma irradiation on quality of Pakistani blood red oranges (Citrus sinensis L. Osbeck)

Effect of gamma irradiation and washing on physicochemical and sensory quality of blood red oranges was investigated. The citrus fruits were packed in cellophane bags and stored at room temperature for 42 days. Two gamma irradiation doses 0.25 and 0.5 kGy alone and in combination with washing were applied to the fruits. Weight loss decreased with gamma irradiation and increased with washing during storage. Acidity and ascorbic acid values were higher for the oranges irradiated at 0.5 kGy and minimum for the washed oranges. Generally, total soluble solids (TSS) increased during the storage period. However, washed samples had the highest concentration and 0.5 kGy-irradiated samples had the lowest TSS at the end of the storage period. Sensory quality qualify by appearance, odour and taste are decreased during storage in both treatments. However, the fruits were still acceptable by the trained observers. It can be inferred from this study that irradiation at 0.5 kGy or in combination with washing is an effective post-harvest technique in keeping the changes in physicochemical and sensory quality to a minimum level during storage.