Enantiomeric Distribution of Chiral Compounds in Orange Juices according to Their Geographical Origins

Abstract

Chiral terpenes in nonprocessed orange juices of different geographical origins were examined by two different approaches: steam distillation–solvent extraction–gas chromatography–mass spectrometry (SDE-GC-MS) and solid-phase microextraction–gas chromatography(SPME-GC). The two sample preparation techniques were compared with regard to their effectiveness in determining the enantiomeric distributions of chiral compounds. Most target compounds exhibited constant enantiomeric ratios in all juices when either of the two approaches was used. Exceptions were found for terpinen-4-ol and β-citronellol, whose of enantiomeric purity ratios varied significantly according to the geographical origin of the sample. These results may aid in guaranteeing the authenticity and thus the quality and safety of orange juice. A comparison between the two extraction procedures revealed SPME to be more reliable for stereochemical studies, since harsh experimental conditions that can bring about racemization are not required in such studies.

Enantiomeric distribution of major chiral volatile organic compounds in juniper‐flavored distillates

“…Finally, the correctness of the determined enantiomeric ratios was checked by two independent sample treatment procedures. Del Castillo et al reported significant differences in the enantiomeric ratios of selected chiral terpenes obtained by SPME and steam distillation in nonprocessed orange juices with regard to geographical origin. For this reason, enantiomeric ratios obtained by SPME and LLE were compared.…”

Relationship between the terpene enantiomeric distribution and the growth cycle of lemon fruit and comparison of two extraction methods

“…the mass spectra of the compounds studied were compared to those in the NIST 2012 Library using MSView software. The order of elution of the enantiomers was obtained from data reported in the literature (14,26) and obtained through analysis of the commercial standards.…”

“…The chiral compounds selected for this study were those that are most abundant in lemon fruit (α-pinene, β-pinene and limonene), as well as one of the principal odorant compounds (linalool) (27). As shown in Figure 1, two injections with two cuts each one were done, the first one to separate β-pinene from limonene and the second one compounds (14,30). To avoid this high-temperature-induced racemization, SDE at reduced pressure (V-SDE) was tested.…”

“…Subsequently, the medium may have become acidic, which would particularly affect linalool, but this does not occur because no significant differences between the percentage of R enantiomers of α-pinene, β-pinene, limonene and linalool obtained using SPME or V-SDE were observed (Figure 4(a) and (b)). Ruiz del Castillo et al (2003) reported differences between the results obtained using SPME and SDE, but they employed SDE at atmospheric pressure. These results show that…”

“…In addition, enantiomers may present different bioactivity (12) The aromatic profile depends on many factors, such as the genotype, chemotype, climatic conditions, season of growth, the part of the plant from which the volatile fraction was derived, among other factors, and may affect the flavour intensity (13). In case of assessing the authenticity of flavouring on the basis of its enantiomeric composition, knowing the consistency of this composition in nature is essential (14). Some studies have focused on the variation of the essential oil composition and its enantiomeric composition according to the season (15)(16)(17), but to our knowledge, none have evaluated the dependence of the enantiomeric distribution on the growth cycle of a lemon fruit.…”