Limonoid content of sour orange varieties

Modern Citrus cultivars are thought to have arisen from three parents: the pummelo, the mandarin, and citron. Taxological and genetic data support that sweet and sour oranges share a common parentage. However, as their name suggests, the organoleptic properties of the fruit from these two families is distinctly different. Analysis of the limonoid content of sour orange varieties has been limited.

Juice samples prepared from a selection of sour orange cultivars were evaluated for their limonoid A-ring lactone, aglycone, and glucoside contents. Limonoate A-ring lactone concentrations ranged from 11.1 to 44. 9 mg L⁻¹, whereas nomilinoate A-ring lactone levels were found not to exceed 1.2 mg L⁻¹. Total limonoid aglycone and total limonoid glucoside concentrations varied from 2.4 to 18.4 mg L⁻¹ and from 149.0 to 612.3 mg L⁻¹, respectively. Limonoid glucoside profiling by liquid chromatography-mass spectrometry suggest that the sour oranges are distinctly different from sweet oranges and other citrus species.

Limonoid aglycone and A-ring contents across sweet and sour oranges are similar, whereas limonoid glucoside profiles are distinctly different. Juice prepared from Citrus maderaspatana had the highest limonoid concentrations among the samples tested and could potentially be used for the isolation of limonoid A-ring lactones and glucosides.