Absence of Bitterness in Navel Oranges from Rooted Cuttings

Abstract

MOST Washington Navel oranges yield a juice which eventually becomes unacceptably bitter. The bitterness, which develops slowly on standing or rapidly on heating, is due to limonoid compounds, principally limonin, present in the fragments of albedo and segment walls incorporated into the juice during extraction. As the fruit ripens, the bitterness becomes less evident, and the rate at which bitterness decreases during ripening is affected markedly by the rootstock on which the tree is grown. Thus, Marsh¹ in California and Kefford and Chandler² in Australia showed that some rootstocks (for example, trifoliate orange) promoted early disappearance of bitterness, while others (for example, rough lemon) encouraged high levels of bitterness at and beyond normal harvesting maturity. In the latter work, organoleptic tests were supported by the yields of crude limonin extracted from the peel of the oranges used in preparation of the juice.