C. Ubeda

Glycosidically bound aroma compounds and impact odorants of four strawberry varieties.

This paper reports the determination of glycosidically bound aroma compounds and the olfactometric analysis in four strawberry varieties (Fuentepina, Camarosa, Candonga and Sabrina). Different hydrolytic strategies were also studied. The results showed significant differences between acid and enzymatic hydrolysis. In general terms, the greater the duration of acid hydrolysis, the higher was the content of norisoprenoids, volatile phenols, benzenes, lactones, Furaneol, and mesifurane. A total of 51 aglycones were identified, 38 of them unreported in strawberry. Olfactometric analyses revealed that the odorants with higher modified frequencies were Furaneol, γ-decalactone, ethyl butanoate, ethyl hexanoate, ethyl 3-methylbutanoate, diacetyl, hexanoic acid, and (Z)-1,5-octadien-3-one. This last compound, described as geranium/green/pepper/lettuce (linear retention index = 1378), was identified for the first time. Differences with regard to fruity, sweet, floral, and green aroma characters were observed among varieties. In Candonga and Fuentepina, the green character overpowered the sweet. In the other two strawberry varieties sweet attributes were stronger than the rest.

Validation of an analytical method for the determination of ethyl carbamate in vinegars

A solid phase extraction method (SPE) using Isolute ENV+ cartridges was validated for the determination of ethyl carbamate (EC) in different kinds of vinegars. The method proved to be quite sensitive, precise and accurate, improving the recovery and LQD of other existing methods for the same purpose. For the optimization of the method, different pH values of the sample were tested, resulting 5.5 the most adequate. Among the 14 samples analysed, only 5 of them had contents of EC above the quantification limits, ranging between 6.73 μg/L and 56.4 μg/L. The highest value was found in red wine vinegar. Taking into account the amount of vinegar consumed in a meal and the limits established for alcoholic beverages in some countries, the levels of ethyl carbamate in the vinegars tested in this work were acceptable.

Recent developments in the analysis of musty odour compounds in water and wine: A review.

One of the most common taints in foods is a musty or earthy odour, which is commonly associated with the activity of microorganisms. Liquid foods, particularly wine and water, can be affected by this defect due to the presence of certain aromatic organic compounds at very low concentrations (ng/L) consistent with human threshold perception levels. The volatile compounds responsible for a mouldy off-aroma include approximately 20 compounds, namely, haloanisoles, geosmin, 2-methylisoborneol, several alkyl-methoxypyrazines, 1-octen-3-ol, 1-octen-3-one, trans-octenol, 3-octanone, fenchol and fenchone. Methods for determining these very low concentrations of odour compounds must be extremely sensitive and selective with efficient preconcentration treatments. A number of extraction techniques based on LLME (liquid-liquid microextraction), SPME (solid-phase microextraction) or SBSE (stir-bar sorptive extraction) can be applied and should be selected on a case-by-case basis. Moreover, recent developments in GC instrumentation coupled to different detection systems can effectively increase the selectivity and sensitivity of the analysis of target compounds.

Fluorescence excitation-emission matrix spectroscopy as a tool for determining quality of sparkling wines.

Browning in sparkling wines was assessed by the use of excitation-emission fluorescence spectroscopy combined with PARAllel FACtor analysis (PARAFAC). Four different cava sparkling wines were monitored during an accelerated browning process and subsequently storage. Fluorescence changes observed during the accelerated browning process were monitored and compared with other conventional parameters: absorbance at 420nm (A420) and the content of 5-hydroxymethyl-2-furfural (5-HMF). A high similarity of the spectral profiles for all sparkling wines analyzed was observed, being explained by a four component PARAFAC model. A high correlation between the third PARAFAC factor (465/530nm) and the commonly used non-enzymatic browning indicators was observed. The fourth PARAFAC factor (280/380nm) gives us also information about the browning process following a first order kinetic reaction. Hence, excitation-emission fluorescence spectroscopy, together with PARAFAC, provides a faster alternative for browning monitoring to conventional methods, as well as useful key indicators for quality control.

A comparative study on aromatic profiles of strawberry vinegars obtained using different conditions in the production process.

Impact odorants in strawberry vinegars produced in different containers (glass, oak and cherry barrels) were determined by gas chromatography-olfactometry using modified frequency (MF) technique, and dynamic headspace gas chromatography-mass spectrometry. Aromatic profile of vinegar from strawberry cooked must was also studied. All strawberry vinegars retained certain impact odorants from strawberries: 3-nonen-2-one, (E,E)-2,4-decadienal, guaiacol, nerolidol, pantolactone+furaneol, eugenol, γ-dodecalactone and phenylacetic acid. Isovaleric acid, pantolactone+furaneol, p-vinylguaiacol, phenylacetic acid and vanillin were the most important aroma-active compounds in all vinegars. The strawberry cooked must vinegar accounted for the highest number of impact odorants. Wood barrels provided more aroma complexity than glass containers. Impact odorants with grassy characteristics were predominant in vinegar from glass containers, and those with sweet and fruity characteristics in vinegars from wood barrels. Principal component analysis indicated that the production process led to differences in the impact odorants.

Volatile profile characterisation of Chilean sparkling wines produced by traditional and Charmat methods via sequential stir bar sorptive extraction.

The volatile compositions of Charmat and traditional Chilean sparkling wines were studied for the first time. For this purpose, EG-Silicone and PDMS polymeric phases were compared and, afterwards, the most adequate was selected. The best extraction method turned out to be a sequential extraction in the headspace and by immersion using two PDMS twisters. A total of 130 compounds were determined. In traditional Chilean sparkling wines, ethyl esters were significantly higher, while acetic esters and ketones were predominant in the Charmat wines. PCA and LDA confirmed the differences in the volatile profiles between the production methods (traditional vs. Charmat).

Location Effects on the Aromatic Composition of Monovarietal cv. Carignan Wines

The aromatic profile of monovarietal Carignan wine has been characterized, and the influence of the geographic origin of the wine on the volatile composition wines from six different zones of Chile and from two different seasons has been studied. The solid-phase microextraction conditions employed were previously studied. An extraction temperature of 45°C, 40 min of incubation, 1.5 g of salt, and 180 sec of fiber desorption were employed for the analysis of the 28 wine samples studied. Sixty-three volatile compounds were determined in cv. Carignan wines, and they were characterized as substantial amounts of ethyl esters and small amounts of volatile acid compounds, among others. Analysis of variance showed significant effects on the “location” factor (p < 0.05), which was corroborated by principal component analysis and linear discriminant analysis, where clear groups were observed regarding wine production area. The geographical origin of the wine affected the volatile composition of the wines studied, and production areas that were closer to the Andes Mountains showed lower concentrations of esters and acids than those wines produced in regions that were closer to the ocean.

Water stress and ripeness effects on the volatile composition of Cabernet Sauvignon wines

BACKGROUND Controlled water deficits affect grape berry physiology and the resulting wines, with volatile composition being the one of the affected parameters. However, there is a potential disconnect between aromatic maturity and sugar accumulation. Accordingly, the effects of three different water status levels over two growing seasons (2014 and 2015) and two different harvest dates on the aroma compounds from Cabernet Sauvignon wines were studied. Volatile compounds were determined using headspace solid phase microextraction coupled with gas chromatoghraphy/mass spectrometry. RESULTS Around 45 volatile compounds were determined in the wines and, among these, esters were affected the most, presenting lower concentrations when the most restrictive water treatment was applied in both years. By contrast, volatile acids presented the highest concentrations when the lowest level of irrigation was applied. On the other hand, a delay in harvesting produced an increase in the total amount of volatile compounds in samples from the most restrictive water treatment. These results are coincident with a principal component analysis that indicated a great separation between years, deficit irrigation treatments and harvest dates. CONCLUSION The results of the present study suggest that a low water supply had a negative effect on the aromatic potential of wines at a similar ripening stage. However, this effect could be countered by harvesting at a later date.

Evaluación de menús ofertados em comedores escolares: comparación entre colegios públicos, privados y concertados

Objetivo: Evaluar los menus ofertados en los colegios publicos, privados y concertados de la ciudad de Sevilla (Espana) para los diferentes grupos de edad escolar. Metodos: Se considero un total de 86 colegios, incluyendo centros publicos, privados y concertados, representando a todos los distritos de la ciudad. Cuatro colegios disponian de cocina propia, mientras el resto tenian contratado un catering. Los menus iban dirigidos a escolares de entre 3 a 16 anos. Se evaluo el grado de cumplimiento de las recomendaciones respecto a la frecuencia mensual de los distintos grupos de alimentos, repeticion de recetas, variabilidad de tecnicas culinarias y equilibrio nutricional. Para el tratamiento estadistico se utilizo el programa Statistica 7. Resultados: En la mayoria de comedores escolares la oferta de frutas, verduras y legumbres era deficitaria a diferencia de los postres lacteos, carnes y patatas. Se observaron diferencias significativas entre los tres tipos de colegio respecto a la frecuencia mensual de alimentos, siendo los publicos los que mas se ajustaban a las recomendaciones. La mayoria de los comedores evaluados no aportaban menus suficientemente detallados asi como se observo falta de variedad de tecnicas culinarias. La energia no se ajustaba a las necesidades de todos los grupos de edad y la distribucion de macronutrientes solo era adecuada en el 50% de los menus. Conclusion: Aunque se ha observado una evolucion favorable de los menus respecto a estudios anteriores hay que seguir trabajando en aumentar la oferta de frutas y verduras, disminuir el aporte de lipidos y proteinas, asi como adaptar la energia de los menus a los diferentes grupos de edad.

Impact Odorants in Strawberry Vinegars

In this work we studied odor-active compounds by gas chromatography-olfactometry in strawberry vinegars obtained by means of double fermentation. Two types of alcoholic fermentation were performed: spontaneous and inoculated. The results show that, during the production process, aromatic compounds characteristic of strawberry (furaneol, mesifuraneol, and γ-decalactone) were preserved and those typical of vinegar (diacetyl, acetic, and isovaleric acids) appeared. Inoculated wine vinegar had more odor zones with high modified frequency (MF) than did spontaneous wine vinegar. The MF of odor zones tentatively identified as acetic, butyric, isovaleric, phenylacetic acids, 2-phenylethanol, pantolactone+furaneol, γ-decalactone, p-vinylguiacol, sotolon, and vanillin point to these compounds as possible impact odorants in strawberry vinegars.