Influence of Household Processing Techniques on Grapefruit (Citrus paradisi var. Macfad) Bioactive Compounds

Grapefruits (Citrus paradisi Var. Macfad) are a good source of bioactive compounds which may potentially reduce the risk of certain diseases. While certain parameters of post harvest factors effect on bioactive compounds are known, the role of house processing techniques such as blending, juicing and squeezing are not studied. Therefore, mature Texas ‘Rio Red’ grapefruits were processed by blending, juicing and hand squeezing techniques and analyzed for their phytochemical content by high performance liquid chromatography (HPLC). Results suggest that grapefruit juice processed by blending had significantly (P < 0.05) higher levels of flavonoids (narirutin, naringin, hesperidin, neohesperidin, didymin and poncirin) and limonin compared to juicing and hand squeezing. Ascorbic acid and citric acid were significantly (P < 0.05) higher in juice processed by juicing and blending, respectively. Furthermore, hand squeezed fruit juice had significantly higher content of dihydroxybergamottin (DHB) than juice processed by juicing and blending. Bergamottin and 5-methoxy-7 gernoxycoumarin (5-M-7-GC) were significantly higher in blended juice compared to juicing and hand squeezing.  Therefore, consuming grapefruit juice processed by blending may provide higher levels of bioactive compounds. In contrast, juice processed by hand squeezing and juicing provides lower levels of limonin, bergamottin and 5-M-7-GC. In conclusion, household processing techniques significantly influence the levels of phytochemicals and processing grapefruits by blending is an ideal technique for obtaining optimum levels of health beneficial bioactive compounds.