5146
J. Agric. Food Chem. 2002, 50, 5146−5148
Volatile Compounds of Psidium salutare (H.B.K.) Berg. Fruit JORGE A. PINO,*,† ROLANDO MARBOT,‡
AND
AVILIO BELLO§
Instituto de Investigaciones para la Industria Alimenticia, Carretera del Guatao km 31/2, La Habana 19200, Cuba; Centro Nacional de Investigaciones Cientı´ficas, La Habana, Cuba; and Instituto Superior Pedago´gico de Pinar del Rı´o, Cuba
Volatile compounds were isolated from Psidium salutare fruits by simultaneous steam distillationsolvent extraction according to the Likens-Nickerson procedure. Compounds were identified by capillary GC and GC-MS. One hundred and fifty compounds were identified in the aroma concentrate, from which limonene, myrcene, and R-pinene were found to be the major constituents in the fruit. KEYWORDS: Psidium salutare (H.B.K.) Berg.; Myrtaceae; fruit volatiles; limonene; myrcene; r-pinene
INTRODUCTION
The species Psidium salutare H.B.K., commonly called “guayabita del pinar”, very much resembles the guava in size of tree and general growth. The small tree, which is endemic of the western part of Cuba, produces a thin-skinned, green fruit about the size of a little olive, with a short sharp point at the flower end. The fruit has little flesh and a pleasant sweet flavor. It is very aromatic and commonly used to prepare an appreciated liquor (1). These aromatic properties led us to investigate its composition to determine the volatile constituents of the fruit. To date, the aroma of P. salutare has not been the subject of a previous study. EXPERIMENTAL PROCEDURES Materials. Fruits were collected at mature stage from a commercial plantation in Pinar del Rı´o in Cuba’s western region and immediately processed. Pure reference standards of acetaldehyde, acetone, acetic acid, methyl acetate, 3-buten-2-one, butanal, propanol, ethyl acetate, 1-butanol, 2-pentanone, pentanal, acetal, 2-pentanol, 2,5-dimethylfuran, 1-pentanol, (Z)-2-penten-1-ol, propanoic acid, hexanal, ethyl butanoate, furfural, 3-methyl-2-butenol, 3-methyl-2-butenal, butanoic acid, 1-hexanol, R-pinene, β-pinene, ethylbenzene, camphene, 6-methyl-5-hepten2-one, pentanoic acid, myrcene, R-terpinene, 1,8-cineole, (E)-2-hexenal, 2-heptanol, 2-heptanone, 2,4-hexadienal, R-terpinene, δ-3-carene, γ-terpinene, myrcene, p-cymene, phenol, hexanal, (Z)-3-hexenol, 1-octanol, benzaldehyde, fenchone, linalool, camphor, borneol, nerol, neral, geraniol, R-terpineol, carvone, ethyl salicylate, trans-carveol, thymol, carvacrol, 1,2,4-triethylbenzene, methyl decanoate, geranyl acetate, vanillin acetate, (E)-nerolidol, (E,E)-farnesol, isopropyl palmitate, (E)phytol, benzyl benzoate, tetradecanoic acid, palmitic acid, and linoleic acid were purchased from Aldrich (Steinheim, Germany). Limonene, 3-methylbutanal, (E)-β-caryophyllene, and R-humulene were obtained from Sigma (Steinhem, Germany), and cis-linalool oxide, trans-linalool oxide, β-fenchol, and terpinen-4-ol were purchased from Fluka (Buchs, Switzerland). Diethyl ether was purchased from Merck (Darmstadt, Germany). * Author to whom correspondence should be addressed (fax +537 2046 553; e-mail
[email protected]). † Instituto de Investigaciones para la Industria Alimenticia. ‡ Centro Nacional de Investigaciones Cientı´ficas. § Instituto Pedago ´ gico de Pinar del Rı´o.
Isolation of Volatile Compounds. After the addition of an internal standard (methyl undecanoate, 2 mg), ground fruits (200 g) were blended with distilled water (800 mL), adjusted to pH 7.0, and simultaneously distilled and extracted for 90 min in a Likens-Nickerson microapparatus with 25 mL of diethyl ether (previously redistilled and checked as to purity). The volatile concentrate was dried over anhydrous sulfate and concentrated to 0.6 mL on a Kuderna-Danish evaporator with a 12-cm Vigreux column and then to 0.2 mL with a gentle nitrogen stream. Gas Chromatography. A Konik 4000A HRGC equipped with a 30 m × 0.25 mm (0.25 µm film thickness) CP-SIL-5CB (5% phenyl-polymethylsiloxane) Chrompack fused-silica capillary column and a flame ionization detector (FID) was used. Injector and detector temperatures were 250 °C. Oven temperature was held at 60 °C for 10 min and then raised to 280 °C at 2 °C/min and held for 40 min. Carrier gas (hydrogen) flow rate was 1 mL/min. These conditions were used for quantitative analysis, by the internal standard method. Quantitative data were obtained by electronic integration of FID areas without the use of correction factors. The recovery of the method was determined by the standard addition technique applied to a sample. The analytes [R-pinene, limonene, ethyl butanoate, 1-hexanol, (Z)-3-hexenol, (E)-β-caryophyllene, (E)-nerolidol, and R-terpineol] were added at two different concentrations. The average recoveries were ∼88-102%, and their relative standard deviations were
