Influence of storage temperature and low-temperature conditioning on the levels of health-promoting compounds in Rio Red grapefruit

Commercial operations use low-temperature conditioning of citrus fruits to reduce the incidence of chilling injury (CI) during cold storage and quarantine treatments. Rio Red grapefruits (Citrus paradisi Macf) were stored for 12 weeks at 11 degrees C or 5 degrees C; an additional set was temperature conditioned at 16 degrees C for 7 days before storing at 5 degrees C (CD). Every 3 weeks, samples were assessed for chilling injury (CI) and health-promoting compounds such as ascorbic acid, carotenoids, limonoids, flavonoids, and furocoumarins. Low-temperature conditioning significantly reduced CI but did not affect the total soluble solids, acidity, and ripening ratio. After 12 weeks of storage, grapefruits showed no significant differences in lycopene, narirutin, poncirin, furocoumarins, and radical scavenging activity in all the three treatments. Limonin was significantly higher (p<.05) in CD fruits, nomilin was significantly higher in fruits stored at 11 degrees C, whereas fruits stored at 5 degrees C had lower levels of naringin, neohesperidin, and didymin after 12 weeks of storage. Low-temperature conditioning treatment helped fruits to retain similar or higher levels of most of the health-promoting compounds by the end of storage period while maintaining better quality than the nonconditioned fruits.