CHANGES IN THE LIMONOID CONTENT DURING DEVELOPMENT OF CITRON FRUIT (CITRUS-MEDICA L)

Limonoid compounds are bitter principals in the citrus fruit. The changes of limonoid in the component parts, seed, flesh, segment membrane, albedo and flavedo, of the citron fruit (Citrus medica L.) , obtained from Azuma town, Kagoshima Prefecture, during the development from November to February were investigated. Limonoids were extracted with ethylacetate and analyzed with high performance liquid chromatography. 1. Different from many other citrus fruits, such as 'Wase satsuma mandarin', 'Natsudaidai' etc., nomilin was a major limonoid in all the parts of citron fruit except seed, in which the content of nomilin was next to that of limonin. 2. The total limonoid concentration in the seed was highest, ranging from 3,270 to 1,600 ppm, followed by segment membrane (350 --> 310 ppm), albedo (250 --> 150 ppm) , flavedo (225 --> 150 ppm) and flesh (45 --> 30 ppm) from November to February. 3. In mature citron fruits, total limonoid content reached the maximal levels in November, and then decreased rapidly in December and then increased slightly in February. 4. During the maturation of the citron fruit from December to February, the total limonoid concentration in all parts except the albedo increased rapidly, followed by a rapid decrease in the over ripe stage. Limonoid concentrations continuously increased during maturation in the albedo and in the flesh from 4 to 15 ppm and from 55 to 170 ppm, respectively.