Degreening and postharvest storage influences 'Star Ruby' grapefruit (Citrus paradisi Macf.) bioactive compounds.

Ethylene is commercially used for artificial degreening of early season grapefruits. The present study investigated the effect of degreening and storage period on Star Ruby grapefruit (Citrus paradisi Macf.) bioactive compounds. Freshly harvested grapefruits were degreened in commercial packing shed for 60h using 2ppm of ethylene at a constant temperature of 20°C. Both degreened and non-degreened (control) fruits were stored at 10°C for 21days and later transferred to 20°C for a period of 14days to simulate shipment and retail store market conditions. Bioactive compounds including carotenoids, limonoids, flavonoids and furocoumarins were analyzed using high performance liquid chromatography. Nomilin was significantly higher (P<0.05) in degreened fruits at 35days after storage. In contrast, flavonoids such as narirutin, naringin and poncirin were significantly (P<0.05) lower in degreened fruits at 35days after storage. Degreening treatment reduced the levels of deacetyl nomilinic acid glucoside and bergamottin after 35days of storage; however, it had no significant effect on total soluble solids, decay, fruit softening, taste, odour, ascorbic acid, β-carotene, lycopene, limonin, neohesperidin, didymin, 6,7-dihydroxybergamottin, 5-geranyloxy-7-methoxycoumarin and radical scavenging activity. Therefore, degreening could be utilized to enhance the grapefruit aesthetic quality, with minimal effect on nutritional quality.