Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/31/2005
Publication Date: 6/30/2005
Citation: Breksa III, A.P., Zukas, A.A., Manners, G.D. 2005. Limonoate A-Ring Lactones: Key Intermediates in the Limonoid Pathway. Meeting Abstract No. 83. August 2005. Washington, DC.
Technical Abstract: Our efforts focus on developing methods to mitigate the negative economic impact of delayed bitterness. Delayed bitterness results from the formation of the bitter dilactone limonoids limonin (1), and nomilin (2), from non-bitter monolactone precursors limonoate A-ring lactone (3), and nomilinoate A-ring lactone (4). Freeze damage or physical damage to citrus fruit, including juicing, instigates this conversion which is catalyzed by the enzyme limonin D-ring lactone hydrolase (LDLH). The presence of bitter limonoids in concentrations in excess of 6 ppm reduces the acceptability of citrus products to consumers. Three recent accomplishments towards our goal include the isolation of 3 and 4, a rapid and robust LC-MS method for the quantification of 3 and 4 in juice samples, and a simple method for the evaluation of LDLH activity in citrus.