No abstract

No abstract

No abstract

This report presents the results of a study conducted to determine the distribution of limonin within the fruit tissues of nine grapefruit cultivars. It was found that the highest limonin levels within the fruit tissues were found in the cotyledon, followed by inner seed coat, outer seed coat, central pith, segment membrane, albedo and flavedo, and juice vesicles, in decreasing amounts. The concentration of limonin in the tissues of the individual cultivars is also presented, and the variation in limonin content within a single tissue and within single fruit is discussed. The limonin content of the fruit of the nine cultivars was also compared. The overall results showed that Davis Krome was significantly higher in limonin content followed by Triumph, Duncan, White Marsh, and Foster Pink (which were statistically equivalent to each other) and then by Thompson Pink, Wheeney, and Mott. Leonardy contained the lowest ppm of limonin. The ranking of the cultivars according to the limonin content of each tissue is also presented.Limonin is the intensely bitter triterpenoid dilactone derivative which is widely distributed throughout the Rutaceae. This compound is of major importance in certain citrus fruits, grapefruits and navel oranges, as well as their processed products. In the past, limonin localization and distribution in citrus fruit and plant parts has received only minimal attention since an assay procedure that is rapid, is sensitive, is objective, and permits a high sample throughout has not existed. We have reported on the recent development of a radioimmunoassay (RIA) for limonin (Weiler and Mansell, 1980;Mansell and Weiler, 1980) which has made it possible to do studies which heretofore were impractical.Recently we have presented the first in a series of reports on the limonin levels in grapefruit cultivars (Manesell and McIntosh, 1980). In this study samples were taken from truckloads of grapefruit being brought into processing plants. This sampling tended to minimize variation within and between fruits and trees but not between different varieties, groves, and trees of different age, nutritional status, and geographical distribution. Statistically significant differences were observed between the various cultivars sampled and between the test houses of the various processing plants.

Limonin and naringin are the two major bitter compounds in Citrus paradisi (grapefruit), and tissuespecific patterns of their distribution are well-established. This study was undertaken to determine the distribution of these compounds within Duncan, Marsh, and Thompson Pink tissues using threedimensional fruit dissection (600-900 samples per fruit) and highly specific radioimmunoassays for limonin and naringin quantification. Results from a GLM ANOVA showed that there was no radial distribution pattern of limonin or naringin accumulation in these fruit. There were statistically significant differences in the axial distribution of these compounds within the fruit tissues. The limonin concentration in flavedo, albedo, outer segment membrane, and juice vesicles increased toward the distal end of the fruit. Naringin concentrations in flavedo, albedo, and outer segment membranes tended to be higher in the center portion of the fruit. Limonoate A-ring monolactone levels are also reported.