Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1997
Publication Date: N/A
Interpretive Summary: The chemical composition of new varieties of citrus needs to be determined because it can affect the acceptability to consumers, the health and nutritional benefit to the consumer, and, consequently, the investment risk to grower and processor. Two new varieties, Oroblanco and Melogold have been newly developed by the University of Callifornia at Riverside and are currently grown in Southern California. These varieties have have not been fully characterized in terms of their chemical components. In this study the exact composition and concentration of two chemical groups which contribute to the bitter flavor in citrus juices were determined. These compounds also have been shown to have potential nutritional benefits to human health, such as anti-cancer activity, prevention of heart disease, and antioxidant activities. This information will aid in promotion of the export of these fruits from the US to the Orient, the major market for these fruits.
Technical Abstract: Oroblanco and Melogold are hybrids obtained from pummelo and grapefruit. Limonoids and flavonoids in both juices were analyzed. Oroblanco and Melogold juices contained low concentrations of limonoid glucosides, an average of 99 and 59 ppm, respectively. However, they contained relatively high concentrations of bitter limonoid aglycones, limonin and nomilin, at levels beyond the limonin bitterness threshold level. For comparison, limonoid glucosides in juices of grapefruit, another pummelo hybrid, were also analyzed. Limonin glucoside was the major limonoid glucoside in all juices analyzed. Nomilin glucoside and nomilinic acid glucosides were also present. Obacunone glucoside was found in grapefruit juices in measurable amounts. Both juices contained bitter flavonoids normally found in grapefruit and pummelo including naringin, neohesperidin and poncerin in total amount of 440 ppm in Oroblanco juice and 495 ppm in Melogold juice. They also contained several other nonbitter flavonoids found in grapefruit.