Response of ‘Nagpur’ mandarin, ‘Mosambi’ sweet orange and ‘Kagzi’ acid lime to gamma radiation
摘要
The effects of irradiation dose and refrigerated storage conditions on ‘Nagpur’ mandarin (Citrus reticulata Blanco), ‘Mosambi’ sweet orange (Citrus sinensis Osbeck) and ‘Kagzi’ acid lime (Citrus aurantifolia Swingle) were investigated. Mature fruits of these three species were treated with 0, 0.25, 0.5, 1 and 1.5kGy radiation. ‘Nagpur’ mandarin and ‘Mosambi’ sweet oranges were stored at 6–7°C and 90–95%r.h. for 75 and 90 days, respectively, while ‘Kagzi’ acid limes were stored at 8±1°C and 90–95%r.h. for 90 days. Physico-chemical parameters, sensory attributes and respiration rate were measured besides losses and disorders. In ‘Nagpur’ mandarin, radiation dose upto 1.5kGy did not cause any rind disorder. Radiation treatments did not reduce the extent of decay. Penicillium rot was delayed in fruit treated with 1.5kGy, while it appeared early in 0kGy. Irradiation doses were ineffective to control rots due to Botryodiplodia theobromae and Alternaria citri. Doses upto 1.5kGy did not cause any significant effect on fruit firmness and juice content; however, total soluble solids increased, while titratable acidity and vitamin ‘C’ content decreased. Texture and flavour scores as recorded after a week, were not affected by irradiation except in 1.5kGy. In ‘Mosambi’ sweet orange, radiation treatments caused peel disorder in the form of brown sunken areas after 90 days and reduced fruit firmness, acidity and vitamin C content. The TSS content was higher in treated fruit. Flavour and texture were not affected by the doses of irradiation used. In treated acid limes (mature yellow), weight loss and decay were higher than untreated fruit (0kGy) although difference was non-significant. Juice, TSS, titratable acidity and vitamin C contents were significantly less in treated fruit than in 0kGy. Texture and flavour scores were also less in treated fruit than in 0kGy. The stem-end rind breakdown was higher in untreated fruit than treated ones although difference was non-significant. Irradiation treatment increased respiration rate in all the three types of citrus fruits considerably. Unlike mandarin and sweet orange, respiration rate increased in acid limes with extension of storage.