Abstract
The bitterness of citrus fruits increases when they are used to prepare marmalade. To study this problem, the effect on bitterness was studied by objective methods with marmalade prepared from a 1 : 1 mixture of two kinds of citrus peel. The limonoid and flavonoid levels were determined by HPLC, and taste was evaluated by a sensory test. The amount of flavonoids was decreased markedly by heating, indicating that they were not responsible for the bitterness. While limonin was also decreased by boiling, the amount of nomilin increased, suggesting that it was responsible for the bitterness. Fruit containing naringin was rated as tasting good (5% singnificance level), but fresh fruit containing a large amount of limonin was not judged favorably. Mixing two different kinds of citrus fruits is suggested as a way for improving the flavor of marmalade.
