ABSTRACT
Citrus fruits have been known and valued for their aroma in food and perfume ever since humans have maintained written records. Often described as the "champagne" of citrus oils, especially cold pressed lime peel oils have raised attention. Particularly peel oils of Citrus latifolia exhibit a pleasant coumarinic, sweet, and balsamic aroma in comparison to its close relative, the Citrus aurantifolia. Those coumarinic notes have not been completely understood until today. Thus, this study aimed to identify the responsible substances and elucidate their contribution and impact on the aroma of cold-pressed lime oil. By combining distillation, fractionation, olfactory detection, and structure elucidation, the responsible key aroma components were identified. A combination of coumarins and their corresponding saturated analogs have been identified to significantly contribute to the typical coumarinic-like aroma, including three new flavor compounds that have not yet been described in the literature as lime oil constituents: 7-methoxy-2-chromanone (3,4-dihydro-7-methoxy-2H-1-benzopyran-2-one; CAS 20921-02-2), 5,7-dimethoxy-2-chromanone (3,4-dihydro-5,7-dimethoxy-2H-1-benzopyran-2-one; CAS 82243-01-4) and 5,6-dihydrobergaptene (5,6-dihydro-4-methoxy-7H-furo[3,2-g][1]benzopyran-7-one; CAS 29050-61-1). The sensorial evaluation of the impact of these components on the lime aroma profile has shown flavor-modulating effects and the ability to enhance aldehydic-peely, juicy, and fruity notes as well as their importance in reproducing the authentic, typical coumarin-like notes.
Subject(s)
Calcium Compounds , Citrus , Coumarins , Flavoring Agents , Odorants , Oxides , Plant Oils , Taste , Humans , Coumarins/chemistry , Odorants/analysis , Plant Oils/chemistry , Citrus/chemistry , Flavoring Agents/chemistry , Male , Female , Adult , Fruit/chemistry , Young Adult , Middle Aged , Smell , Gas Chromatography-Mass SpectrometryABSTRACT
The hydrofluorination of enolizable ynones with AgF in t-BuOH/DMF is reported. The formation of furans as side products can be suppressed using 2,2'-biphenol. The corresponding ß-fluoroenones were obtained with good Z-selectivity. A variety of functional groups are tolerated. ß-Fluoroenones are vinylogous acid fluorides whose hydrolysis to vinylogous acids can be avoided under the reported reaction conditions. The asymmetric 1,2-reduction of ß-fluoroenones to 3-fluoroallylic alcohols is possible with pinacolborane and a Ni(0) catalyst prepared from a pyrimidyloxazoline ligand.
