Elsevier

Food Chemistry

Volume 105, Issue 4, 2007, Pages 1748-1754
Food Chemistry

Analytical, Nutritional and Clinical Methods
HS-SPME coupled to GC/MS for quality control of Juniperus communis L. berries used for gin aromatization

https://doi.org/10.1016/j.foodchem.2007.03.026Get rights and content

Abstract

HS-SPME coupled to GC/MS was applied to the analysis of the volatile fraction of Juniperus communis L. berries, which are the principal ingredient used for gin aromatization. Seventy seven compounds were identified by comparison with reference compounds or tentatively identified by comparing their mass spectra and retention index with those reported in mass spectra libraries and literature, respectively. Seventy four were detected by SPME and sixty eight were detected by solvent distillation extraction (SDE). These were mainly mono- and sesquiterpenic compounds that represented more than the 80% of the gin’s volatile composition. A high percent content was due to monoterpenoids, whose analysis could be important for the assessment of sensory quality control of juniper due to their impact on gin aroma. The main monoterpenoids detected in the headspace of the juniper berries from two periods of collection were terpinen-4-ol, p-cymene, β-myrcene, γ-terpinene, α-pinene and limonene. These represented more than the 70% of the sample’s volatile fraction. The proposed SPME method required short times and the low cost of analysis and enabled to detect a number of compounds comparable with SDE or much higher than the number of compounds reported by other extraction techniques. The results suggested the suitability of this technique for the assessment of the volatile composition of juniper berries intended for gin flavouring.

Introduction

Common juniper, Juniperus communis L. (Cupressaceae) is an aromatic and evergreen shrub, whose berries are known for their physiological properties (Barjaktarović et al., 2005, Kallio and Jünger-Mannermaa, 1989). Juniper berries are widely used in flavours, perfumes and pharmaceuticals and to aromatise alcoholic beverages. In particular, they are used with other botanical ingredients in the production of commonly consumed juniper-based spirits, such as gin (Aylott, 2003). According to European regulations (EEC 1576/89), the main flavour in the most common and popular type of gin (London dry gin), which belongs to the “Distilled gin” class, should come from juniper berries. In fact, the “juniper” note was reported as the sensory characteristic distinguishing gins from other alcoholic beverages (McDonnell, Hulin-Bertaud, Sheehan, & Delahunty, 2001). Therefore, the main impact on the perception of dry gin flavour should be related to the presence of several aromatic volatile and semivolatile compounds derived from juniper berries. For this reason, the assessment of the volatile and semivolatile composition of this raw material is of great importance to assure the gin’s final sensory quality. The composition of juniper essential oil may be influenced by several factors, such as the growth site, the plant age, the bushes form and the berries ripeness (Angioni et al., 2003, Kallio and Jünger-Mannermaa, 1989).

Several analytical methods are available for analysing essential oil components from plant materials. Distillation methods such as steam distillation (SD), distillation-solvent extraction (SDE), microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE) have traditionally been applied in this analysis. SDE appears to be the most favourable method for recovering mono- and sesquiterpenes and their oxygenated analogues. Heavier components (diterpenoids and phytosterols) have only been observed in MAE and SFE extracts (Marriott, Shellie, & Cornwell, 2001). One of the disadvantages of the distillation method is that the essential oils may undergo chemical alterations. In addition, heat-sensitive compounds can easily be destroyed. Solvent extraction may cause loss of volatiles during the vacuum evaporation of the solvent (Pourmortazevi, Baghaee, & Mirhosseini, 2004). Moreover, these techniques are time consuming. SFE avoids these problems, but it is expensive on a laboratory scale. Headspace techniques are readily applicable to qualitative analysis. They can be used for comparison and quality control purposes or for the investigation of possible adulteration. These techniques provide information on the compounds in the vapour phase, which are mainly responsible for the odour of the product (Coleman & Lawrence, 1997).

The qualitative and quantitative composition of juniper berries’ essential oil has been subject to several investigations (Angioni et al., 2003, Barjaktarović et al., 2005, Chatzopoulou et al., 2002, Chatzopoulou and Katsiotis, 1995, Gonny et al., 2006, Kallio and Jünger-Mannermaa, 1989, Marongiu et al., 2006, Ochocka et al., 1997, Shahmir et al., 2003). However, few studies have been carried out on the headspace volatiles of juniper berries. At the best of our knowledge, only the static headspace technique has been applied for the analysis of volatile constituents of J. communis cones. Twenty terpenic compounds were detected in this analysis (Chatzopoulou & Katsiotis, 2006). Among headspace techniques, solid phase microextraction (SPME) is a rapid, simple, inexpensive and solvent free technique for the extraction and preconcentration of volatile compounds. It is carried out by a fused silica fibre that is coated with different stationary phases and characterized by its high sensitivity to volatile organic compounds (Yang & Peppard, 1994). In recent years, this technique has been proposed for evaluating the aromatic quality control of several foods (Kataoka et al., 2000, Plutowska and Wardencki, 2007). SPME’s applications have been described in the analysis of the volatile compounds of several plant species (Bicchi et al., 2000, Pawliszyn, 1999). However, to date no literature is available on its application to the analysis of juniper berries.

In the present study, the suitability of SPME coupled to gas chromatography/mass spectrometry (GC/MS) was evaluated as a simple and inexpensive method for undertaking the volatile composition analysis of J. communis berries used for dry gin aromatization.

Section snippets

Reagents and plant material

Standard compounds β-myrcene, (S)-(−)-limonene, linalool, (−)-α-pinene, (−)-β-pinene, γ-terpinene, p-cymene, bornyl acetate, (−)-α-terpineol, (+)-terpinen-4-ol, (−)-β-citronellol, t-β-farnesene, nonanal benzaldehyde and manool (4aR-trans-5-(1,5,5,8aS-tetramethyl-2-methylenedecahydro-1-naphthalenyl)-3-R-methyl-1-penten-3-ol) were purchased from Fluka-Sigma-Aldrich (St. Louis, Missouri, USA) and Fluka. Caryophyllene oxide, β-elemol and β-eudesmol were from M.C.M. Klosterfrau (Köln, Germany). The

Results and discussion

The headspace of J. communis berries intended for dry gin aromatization was analysed by applying the analytical method previously developed for the analysis of gin headspace (Vichi, Riu-Aumatell, Mora-Pons, Buxaderas, & Lopez-Tamames, 2005). The SPME extraction conditions were chosen in order to favour the determination of the less volatile terpenic compounds in addition to the more volatile terpenoids. Besides the more volatile monoterpenoids, which appeared as major compounds (Table 1), the

Acknowledgements

This study was supported by the Generalitat de Catalunya, project 2005SGR00156; by the Ministerio de Ciencia y Tecnología (MCYT), project AGL2005-03451/ALI; and by the Secretaría de Estado de Educación y Universidades (Ministerio de Educación y Ciencia), Ref. SB2003-0118.

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