Optimisation of solid phase microextraction (SPME) for the analysis of volatile compounds in dry‐cured ham

Abstract

Solid phase microextraction (SPME) has been shown to be an effective tool for analysing volatile compounds. The aim of this study was to optimise the conditions for the application of SPME in the analysis of volatile compounds in dry-cured ham. The effects of exposure time and fibre coating were investigated while maintaining the dry-cured ham at 30°C to avoid artefact generation due to possible temperature effects. A divinylbenzene/Carboxen on polydimethylsiloxane (DVB/CAR/PDMS) coating showed the best extraction performance for medium-and high-molecular-weight analytes, whilst a Carboxen on polydimethylsiloxane (CAR/PDMS) coating gave the best results for lowmolecular-weight compounds. A total of 70 different compounds were extracted by the two fibre coatings and identified. Sixty compounds were extracted by the DVB/CAR/PDMS fibre, whilst only 41 of these were found with the CAR/PDMS fibre. On the other hand, 10 additional volatile compounds were extracted by the CAR/PDMS coating, all of them being of low molecular weight. Two of the major compounds extracted, hexanal and 2-pentanone, were found in high proportion in both fibre coatings. The extraction yields of dry-cured ham volatile compounds varied according to the fibre coating used and the time of exposure. Therefore extraction conditions should be selected depending on the objective of the study. INTRODUCTIONSolid phase microextraction (SPME) is a simple method for the quantitative analysis of volatile compounds occurring in a wide variety of foods. 1 A fused silica fibre is coated with a suitable adsorbent phase and bound to the tip of a syringe plunger. The plunger is retracted into the needle to protect the delicate fibre. The needle is used to pierce the septum of a sealed vial containing the sample, and the SPME fibre is then extended. Analyte molecules are adsorbed by the coating and, after equilibration, the analytes are thermally desorbed in the injection port of a gas chromatograph and transferred onto the head of a capillary column for subsequent separation and identification. SPME offers certain advantages over other sampling techniques. It is inexpensive, avoids the use of solvents and does not require extended sample preparation, resulting in time saving. 2 During headspace analysis by SPME, exhaustive extraction does not occur; instead, an equilibrium is reached between the matrix and the stationary phase coating the fibre. 3 There are many factors that affect SPME fibre performance, such as

Encapsulation of liquid smoke flavoring in ca-alginate and ca-alginate-chitosan beads

“…The samples were heated in a thermo block (Equilab 2050-ICE, Paris, France) during 60 min at 30°C to equilibrate the headspace for to reach equilibrium. Instrumental aromatic profiles of the samples were obtained from the aromas to be released in the headspaces of the tubes, by the technique of solid phase microextraction (SPME) where the volatiles were adsorbed by the fiber Carboxen/Polydimethylsiloxane (Car/PDMS) and were subsequently released into the injection port of gas chromatograph Shimadzu GC-17 series equipped with a mass selective detector GCMS QP5050A Shimadzu (Tokyo, Japan) for the corresponding separation, identification and analysis (Gianelli et al 2002(Gianelli et al , 2003. The fiber was exposed for 5 min in a normal position open purge valve (splitless mode) for complete desorption at 230°C, after the time required SPME device was removed.…”

Changes in SPME-extracted volatile compounds from Iberian ham during ripening

“…This type of fibre was chosen because of its high sensitivity (Brunton et al, 2000) and it has been recommended to extract the dry-cured ham volatile compounds (Gianelli et al, 2002;García-Esteban et al, 2004). Prior to extraction analysis, the SPME fibre was preconditioned at 280 °C for 45 min in the GC injection port.…”

“…In addition, as a low extraction temperature can be used, SPME could give a better estimation of the aroma profile as it is perceived by the human nose (reviewed by Kataoka et al, 2000;Brunton et al, 2000). SPME has been widely used to extract volatile compounds in several foods and drinks (Chin et al, 1996;Elmore et al, 1997;Bazemore et al, 1999;Marsili, 1999) and also in dry-cured ham (Gianelli et al, 2002;García-Esteban et al, 2004) and Iberian ham (Ruiz et al, 1998(Ruiz et al, , 2001Andres et al, 2002;Ramirez and Cava, 2007). Andrés et al (2002Andrés et al ( , 2007 investigated the changes in the volatile compounds of Iberian ham during ripening by using a direct-extraction device for the SPME extraction, showing large fluctuations in the volatile compound abundances.…”

A comparative qualitative study of the profile of volatile organic compounds associated with Salmonella contamination of packaged aged and fresh beef by HS-SPME/GC-MS

“…Although SPME has maximum sensitivity at the equilibrium point, full equilibrium is not necessary for the purpose of identification of volatiles and for quantification of the same, because of the linear relationship between the amount of analyte absorbed by the SPME fiber and its initial concentration in the sample matrix under nonequilibrium conditions (Shang et al 2002). The use of SPME in conjunction with GC-MS has been reported for the extraction of organic compounds from several matrices such as Salmonella-infected beef (Ogihara et al 2000), cooked beef (Machiels and Istasse 2003), cured hams (Gianelli et al 2002;Luna et al 2006), pork (Elmore et al 2000;Ramírez et al 2004), cooked turkey (Brunton et al 2002), chicken myofibrils (Goodridge et al 2003) and fermented sausages (Marco et al 2004). SPME has also proven to be useful for the detection of contamination of food by microbial pathogens.…”