Influence of Ethylene Treatment on Bioactive Compounds of 'Rio Red' Grapefruit

Influence of postharvest degreening treatment on 'Rio Red' grapefruit quality and bioactive compounds such as carotenoids, ascorbic acid, limonoids, flavonoids and furocoumarins was investigated. Fruits were degreened in commercial packing shed with 3.5 ppm ethylene at 21 °C and 80% RH. Non-degreened fruits were used as a control. Both degreened and non-degreened fruits were stored under simulated market conditions at 10 °C for 3 weeks and 21 °C for 2 weeks. Ascorbic acid content was significantly higher in degreened fruits after 35 days of storage, while non-degreened fruits had higher ascorbic acid levels at 7 days of storage. The levels of limonoids [deacetyl nomilinic acid (DNAG), limonin, nomilin], flavonoids (narirutin, naringin, neohesperidin, didymin, and poncirin), and furocoumarin (6,7-dihydroxycoumarin (DHB) were quantified by HPLC in both the treatments.  After 35 days of storage there was no significant difference observed in limonoids, flavonoids, and carotenoids, namely β-carotene and lycopene contents between both the treatments. In both treatments β-carotene and lycopene levels increased gradually up to 14 days and maintained their initial levels after 35 days of storage. DNAG, limonin and all flavonoids were significantly higher while DHB was lower in degreened fruits at 7 days of storage. DHB was significantly lower in degreened fruits after 35 days of storage. Overall ethylene treatment had a significant influence on certain bioactive compounds present in 'Rio Red' grapefruit. This project is based upon work supported by the USDA-NIFA # 2010-34402-20875 “Designing Foods for Health” through the VFIC and Research Grant Award No. TB- 8056 - 08 from the Texas Department of Agriculture, Texas Israel Exchange and the United States–Israel Binational Agricultural Research and Development Fund.