Submitted to: Journal of Chromatography A
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/16/2004
Publication Date: 1/6/2005
Citation: Breksa III, A.P., Zukas, A.A., Manners, G.D. 2005. Determination of Limonoate and Nomilinoate A-ring Lactones in Citrus Juices by Liquid Chromatography-Electrospray Ionization Mass Spectrometry. Journal of Chromatography A. V. 1064:187-191. Interpretive Summary: Freeze damage or physical damage to citrus fruit, including juicing, initiates the formation of the bitter dilactone limonoids from non-bitter monolactone precursors. This phenomenon is referred to as delayed bitterness and is a major problem for both fresh fruit and juice producers worldwide. The major limonoids associated with delayed bitterness are limonin and nomilin. We present a rapid and sensitive method for the quantification of their corresponding precursors: limonoate A-ring lactone (LARL) and nomilinoate limonoate A-ring lactone (NARL). This method provides a valuable tool for citrus growers and juice producers to evaluate the susceptibility of a fruit or juice to delayed bitterness.
Technical Abstract: The development of delayed bitterness in citrus products is a major problem to citrus producers and juice processors worldwide. A rapid and sensitive electrospray ionization liquid chromatography-mass spectrometry (ESI LC-MS) method has been developed to quantify the recognized precursors of limonoid derived delayed bitterness, limonoate and nomilinoate A-ring lactones (LARL and NARL), in a wide variety of citrus juices. The limonoid A-ring lactones were isolated by solid-phase extraction from juice samples and analyzed by negative ion ESI LC-MS utilizing internal calibrators and an internal standard with a lower limit of quantification of 75 pg.