Molecular-Sensory Decoding of the Citrus latifolia Aroma.

A modified aroma extract dilution approach (AEDA), followed by the determination of flavor dilution (FD) factors, a quantitative analysis and calculation of the relative flavor activity (RFA) and odor activity values (OAVs) as well as recombination experiments were conducted to evaluate the odor- and taste-relevant components of cold-pressed Citrus latifolia peel oil. A 2-fold concentration by distillation and reanalysis, compared with the original oil, revealed relevant components. Partition of the odor-active substances into four reconstitution groups according to their respective FD factors, followed by a recombination, allowed for a better understanding of the contribution of each FD-factor group to the overall aroma. Especially α-pinene, limonene, γ-terpinene, and 7-methoxycoumarin contribute significantly to the distinct aroma profile of C. latifolia. Heptadecanal (CAS 629-90-3) was described for the first time as an odor-active substance in an enriched C. latifolia peel oil. Campherenyl acetate (CAS 18530-07-9) was identified in nature for the first time and described with a herbal, minty and citrus-like odor. The odor profile of the final recombinant mixture, containing 36 components, was similar to cold-pressed C. latifolia peel oil for most descriptors, whereas the taste profile was described as more aldehydic and citral-like.

Sensory Impact of Novel Dihydrocoumarins in Native Lime Oils.

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.

Investigations into the Natural Occurrence of 1-Phenylethyl Acetate (Styrallyl Acetate).

So far, the occurrence of the flavor constituent 1-phenylethyl acetate in a natural source has not been unambiguously confirmed. The present work provides the detailed identification of 1-phenylethyl acetate from clove (Syzygium aromaticum (L.) Merr. & L.M. Perry) buds. In addition, headspace solid-phase microextraction-gas chromatography/mass spectrometry (GC/MS) analysis revealed further occurrence of 1-phenylethyl acetate in cocoa pulp and grape hyacinth flowers. A total of 15.2 g of essential oil was recovered from 7.2 kg of clove buds by simultaneous distillation-extraction followed by vacuum distillation. The distillate obtained was fractionated by silica column chromatography, whereby a significant enrichment of 1-phenylethyl acetate was achieved. The fraction containing the target analyte was further purified by preparative high-performance liquid chromatography, resulting in a final purity of ∼93.0%, yielding a total of 1 to 2 mg of 1-phenylethyl acetate. Identification of the isolated compound was achieved by GC/MS, infrared spectroscopy, enantioselective GC, isotope ratio MS, and nuclear magnetic resonance spectroscopy. Enantioselective GC/MS analysis revealed an enantiomeric excess of 60% (1S)-(-)-1-phenylethyl acetate in the isolate. The δ13CV-PDB value of -32.5 ± 0.5‰ was in accordance with that of C3-plants and other constituents found in genuine clove extracts.