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

Apple juice was subjected to centrifugal block cryoconcentration (CBCC) for three cycles and their effect on the physicochemical properties, bioactive compounds, antioxidant activity, volatile profile, and sensory analysis was investigated. In the final cycle, the solutes were approximately four-fold of the initial condition (≈14 °Brix) and the color (ΔE* ≈ 25.0) was darker than the fresh juice, with bioactive compound concentration values close to 819 mg GAE/100 g d.m., 248 and 345 mg CEQ/100 g d.m. for total polyphenol, flavonoid, and flavanol content, respectively, equivalent to a retention of over 60%. DPPH and FRAP assays presented high antioxidant activities, with values of approximately 1803 μmol TE/100 g d.m. and 2936 μmol TE/100 g d.m, respectively. The cryoconcentrate showed a similar aromatic profile to the fresh juice, with 29 and 28 volatile compounds identified, respectively. The centrifugal force allowed to obtain excellent process parameters, with 73%, 0.87 (kg/kg), and 85% for efficiency, solute yield, and percentage of concentrate, respectively. Sensory evaluation shows that the odor, aroma, and flavor of fresh sample were remained in the reconstituted cryoconcentrate sample, with good qualifications (four points in a five-score hedonic scale) by trained panelists. Therefore, CBCC can preserve important quality attributes from apple juice.

The aim of this work was to identify and quantify the volatile compounds in five different commercial brands of charqui and longaniza sausages. Volatile compounds were extracted from some samples headspace using solid phase microextraction (SPME). The identification and quantification were made through the gas chromatography with a mass-selective detector (GS-MS). Fifty-four volatile compounds were identified in charqui samples and thirty-two volatile compounds in longaniza sausages. The chemical groups of the volatile compounds found in both the products were: aldehydes, alcohols, ketones, organic acids, furans, aromatic and aliphatic hydrocarbons. Significant differences were found (p<0.05) in the volatile compounds among the brands of longaniza and charqui.A characteristic volatile compounds profile was not found in the analyzed products. However, an important percentage of the volatile compounds in charqui came from the lipid oxidation. In the case of longanizas sausages, volatile compounds come mainly from the carbohydrates fermentation and spices.

Quality properties of concentrate pineapple juice obtained by block freeze crystallization (BFC) and evaporation technology are investigated. After three concentration cycles, the solutes were approximately 3.2 times compared to the initial condition and the final color was darker than that of the fresh juice. BFC allowed for higher bioactive compounds retention than evaporation in terms of total phenolic, flavonoid, and anthocyanin content. The cryoconcentrate juice showed a similar aromatic profile to the fresh juice, with 26 and 23 compounds, respectively. Conversely, only seven volatile compounds were identified in the evaporate sample. Finally, BFC is an effective technology to preserve important quality properties from fresh fruit juices such as color, polyphenols, and aromatic profile.

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