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Jerez de la Frontera, Spain

Pineiro Z.,IFAPA Rancho de la Merced | Marrufo-Curtido A.,IFAPA Rancho de la Merced | Serrano M.J.,IFAPA Rancho de la Merced | Palma M.,University of Cadiz
Molecules | Year: 2016

An analytical ultrasound-assisted extraction (UAE) method has been optimized and validated for the rapid extraction of stilbenes from grape canes. The influence of sample pre-treatment (oven or freeze-drying) and several extraction variables (solvent, sample-solvent ratio and extraction time between others) on the extraction process were analyzed. The new method allowed the main stilbenes in grape canes to be extracted in just 10 min, with an extraction temperature of 75°C and 60% ethanol in water as the extraction solvent. Validation of the extraction method was based on analytical properties. The resulting RSDs (n = 5) for interday/intraday precision were less than 10%. Furthermore, the method was successfully applied in the analysis of 20 different grape cane samples. The result showed that grape cane byproducts are potentially sources of bioactive compounds of interest for pharmaceutical and food industries. © 2016 by the authors; licensee MDPI. Source


Pineiro Z.,IFAPA Rancho de la Merced | Cantos-Villar E.,IFAPA Rancho de la Merced | Palma M.,University of Cadiz | Puertas B.,IFAPA Rancho de la Merced
Journal of Agricultural and Food Chemistry | Year: 2011

A validated HPLC method with fluorescence detection for the simultaneous quantification of hydroxytyrosol and tyrosol in red wines is described. Detection conditions for both compounds were optimized (excitation at 279 and 278 and emission at 631 and 598 nm for hydroxytyrosol and tyrosol, respectively). The validation of the analytical method was based on selectivity, linearity, robustness, detection and quantification limits, repeatability, and recovery. The detection and quantification limits in red wines were set at 0.023 and 0.076 mg L -1 for hydroxytyrosol and at 0.007 and 0.024 mg L -1 for tyrosol determination, respectively. Precision values, both within-day and between-day (n = 5), remained below 3% for both compounds. In addition, a fractional factorial experimental design was developed to analyze the influence of six different conditions on analysis. The final optimized HPLC-fluorescence method allowed the analysis of 30 nonpretreated Spanish red wines to evaluate their hydroxytyrosol and tyrosol contents. © 2011 American Chemical Society. Source


Pineiro Z.,IFAPA Rancho de la Merced | Guerrero R.F.,IFAPA Rancho de la Merced | Fernandez-Marin M.I.,IFAPA Rancho de la Merced | Cantos-Villar E.,IFAPA Rancho de la Merced | Palma M.,University of Cadiz
Journal of Agricultural and Food Chemistry | Year: 2013

A new method for fast determination of stilbenoids from grape stems was developed. Ultrasound-assisted extraction was applied prior to chromatographic determination of stilbenoids in the extracts, and the stability of stilbenoids under extraction conditions was checked. A fractional experimental design was developed to analyze the influence on the extraction process of seven different extraction variables: temperature, ultrasound amplitude, ultrasonic cycle duration, ultrasonic probe type, time, sample-solvent ratio, and solvent (mixtures of ethanol and water). The most important variables for the recovery of major stilbenoids were studied and the final conditions optimized. With this new method, the main stilbenoids found in grape stems can be extracted in 15 min, using 75 C as the extraction temperature and 80% ethanol as the extraction solvent, and no cleaning step with organic solvent is needed. The optimized method allowed for the analysis of stilbenoid content from 22 grape stem samples, many of them analyzed for the first time. © 2013 American Chemical Society. Source

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