Search

Several experiments were conducted to developed orange based vinegar by surface culture. The addition of sugar (sucrose and concentrated must) and the presence/absence of peel in the raw material (squeezed juice, peeled orange, non-peeled orange plus squeezed juice) have been studied during the development of the final product. Polyphenolic and volatile characterization and sensory analysis have also been carried out. The polyphenolic and volatile content of the resulting wines and vinegars showed significant differences depending upon the raw material used. In general, the complexity of the polyphenolic and volatile profiles increased for experiments in which orange peel was included in the raw material. Sensory analysis revealed significant differences between the samples in respect of both sugar addition and raw material. The vinegars using sugar, peeled orange and non-peeled orange plus squeezed juice raw materials, had more preference and keeping in view relative efficiency of the process, vinegar made from the peeled orange material was considered to be best.

Head space sorptive extraction (HSSE) has been evaluated for the analysis of volatile compounds from oak wood in wines. The extraction conditions have been optimized using a two-level factorial design. After optimization, the final extraction conditions were: PDMS stir bars (20 mm length × 0.5 mm film thickness), sample volume of 5 mL, extraction time 120 min, stirring speed 2000 rpm, and NaCl until saturation. The HSSE optimized method was further validated and showed high linearity (r 2 > 0.9960), adequate detection and quantification limits and linear ranges for the analysis of these compounds in aged wines. Moreover, it provided good values of analytical parameters such as precision and recovery (3.49–11.22 % for intra-assay precision, 4.35–8.77 % for inter-assay precision, and 70.6–124 % for recovery). The method was finally applied to different types of fortified wines (Mistelle, Fino and Oloroso wine) from Condado de Huelva Denomination of Origin submitted to different periods of aging in oak wood.

Dietary fiber derived from citrus fruits was added to vinegar. Different sources and quantities of fiber and storage conditions have been scrutinized. Formulated vinegars were evaluated on the basis of their phenolic profile, volatile composition and sensory analysis. The addition of citrus fiber enhanced the phenolic and volatile profile of the resulted vinegars. Whereas lemon fiber contributed mostly to the enrichment of the polyphenolic composition, orange fiber was that which increased in a higher way the volatile composition of the vinegars. Moreover, the content of hydroxycinnamic acid derivatives and the majority of volatile compounds decreased as the dose of fiber increased. Furthermore, the judges preferred fiber-enriched vinegars, but in different quantities depending of the fiber source. This preference was mainly based on citric attribute, contributing several terpenes and ketones derived from them. The addition of citrus fiber to vinegar did not result in a marked storage-dependence.

A study of accelerated aging on an industrial scale, employing both microoxygenation and oak chips, of a Sherry wine vinegar has been carried out. The effect of these two factors, microoxygenation and oak chips, on polyphenolic and volatile compounds, and sensorial parameters has been evaluated. The dose of oxygen applied to the vinegar and the use of chips provoke important changes in its content in polyphenols and volatile compounds and make it similar to the profile obtained using traditional aging. An alternative method of aging is proposed, using 5 g/L of chips and a dose of oxygen around 70 mL/L month. With the proposed method, and according to the sensorial and analytical results obtained, vinegars similar to those traditionally aged can be obtained by accelerated aging with microoxygenation and chips in shorter periods of time. In our case, a final reduction of 86% of time is achieved with the proposed method.

Aroma compounds are most closely associated with the volatile fraction of foods. Common analytical separation procedures employed to analyse volatile compounds need, even today, that prior to GC analysis of an aroma or a fragrance, these compounds be concentrated or/and isolated from the non-volatile matrix. This step constitutes a problem that has still not been satisfactorily resolved and for this, several sample preparation methods can be found into the bibliography. This review gives a brief overview of solid phase extraction techniques to analyse volatiles. Procedures such as solid phase extraction (SPE), solid phase microextraction (SPME), stir bar sorptive extraction (SBSE), and the recent solid phase dynamic extraction (SPDE) will be discussed and critically evaluated. Contemporary applications of these techniques to the study of volatile compounds in wine and other enological products will be presented.

The characterization of the volatile composition that could have relevance on the organoleptic profile of Andalusian sweet wines obtained from Muscat and Pedro Ximenez grapes has been carried out. Twenty commercial samples, ten from Pedro Ximenez grapes and ten for Muscat grapes, have been studied. Various different chemometric tools have been applied in the analysis of the results. Using Cluster analysis and principal component analysis the samples have been grouped according to grape variety. Linear discriminate analysis allowed a 100% differentiation according to grape variety.

Experiments of accelerated oxidation of “Fino” Sherry wines have been conducted at different temperatures (25 and 45 °C) and under the influence of UV–Vis radiation (a xenon lamp of 1500 W). Two types of glass bottle were employed: topaz bottles (with low values of transmittance in the UV–Vis range) and transparent bottles. To identify significant differences between the wine before and after being subjected to the influence of these factors, the values of absorbance at 420 nm and the concentrations of various polyphenolic and volatile compounds were submitted to a multivariate variance analysis. The three factors “temperature”, “radiation”, and “time” had a statistically significant effect on the values of absorbance at 420 nm and on the concentration of most of the polyphenolic and volatile compounds, while the “bottle” factor was only significant for polyphenol content. All the wines showed losses in several polyphenolic compounds, which were more severe for the wines bottled in transparent glass. The combined application of high temperature and UV–Vis radiation provoked significant decreases in most of the volatile compounds monitored.

A study has been conducted of the separation of sugar acids (gluconic, galacturonic and glucuronic acids) by capillary electrophoresis using indirect UV detection. We have tested various background electrolytes: p-hydroxibenzoic acid, sorbic acid, potassium hydrogen phthalate, protocatechuic acid, α-resorcylic acid and β-resorcylic acid. The choice between these electrolytes was made on the basis of studies of electrophoretic mobility and absorbance values at the wavelengths of our CE system. Of all the electrolytes tested, it was found that β-resorcylic acid best met the required characteristics. The best separation of the three acid was achieved with a time of 8 min, for an electrolyte consisting of 5 mM β-resorcylic acid, 1 mM TTAOH (pH 3.0), indirect detection at 214 nm, -20 kV of run voltage and capillary of 60 cm length and 75 µm i.d. It was found that the proposed method is applicable to samples of both must and wine, and that the samples do not require any prior treatment apart from centrifugation (only in the case of must), filtration and dilution in suitable proportion.