Time filter

Source Type

Melendez E.,Estacion Enologica de Haro | Sarabia L.A.,University of Burgos | Ortiz M.C.,University of Burgos
Chemometrics and Intelligent Laboratory Systems

The proper ripening of grapes is the key to obtain a high-quality wine. Ripening is a temporal process that is influenced, in addition to uncontrollable climate factors, by the spatial distribution of the vineyard and planted variety. It is a complex process that cannot be characterized by a single parameter; rather, it is a modification of the profile of the compounds of the grape. This paper analyzes the joint evolution of twelve physicochemical parameters determined in red grapes from four different varieties, in sixteen representative (in both geographical and edaphic point of view) plots belonging to the Qualified Designation of Origin (DOC) Rioja. Samples were collected in September 2009 during four consecutive weeks prior to harvest. The data are naturally structured in a three-dimensional cube of data (named tensor) with these profiles: sample (plot/variety), physicochemical, and temporal. For the first time, studies are made for jointly analyzing the effect of the spatial and temporal distribution on the physicochemical profile of the grape. A PARAFAC model shows an internal data structure that accurately reproduces the ripening process with its distinctive features according to plot/variety, evolution of the physicochemical parameter of grapes, and ripening time. PARAFAC analysis reveals the different grape maturity depending on the vineyard's situation (zone and altitude) and the grape variety (garnacha, tempranillo, graciano, mazuelo). The obtained information allows evaluating the attainable quality in the grape related to the potential of the zone and its variety. © 2015 Elsevier B.V. Source

Anon A.,Technical University of Madrid | Lopez J.F.,Technical University of Madrid | Hernando D.,Estacion Enologica de Haro | Orriols I.,Estacion de Viticultura y Enologia de Galicia | And 2 more authors.
Food Chemistry

The effects of five technological procedures and of the contents of total anthocyanins and condensed tannins on 19 fermentation-related aroma compounds of young red Mencia wines were studied. Multifactor ANOVA revealed that levels of those volatiles changed significantly over the length of storage in bottles and, to a lesser extent, due to other technological factors considered; total anthocyanins and condensed tannins also changed significantly as a result of the five practices assayed. Five aroma compounds possessed an odour activity value >1 in all wines, and another four in some wines. Linear correlation among volatile compounds and general phenolic composition revealed that total anthocyanins were highly related to 14 different aroma compounds. Multifactor ANOVA, considering the content of total anthocyanins as a sixth random factor, revealed that this parameter affected significantly the contents of ethyl lactate, ethyl isovalerate, 1-pentanol and ethyl octanoate. Thus, the aroma of young red Mencia wines may be affected by levels of total anthocyanins.© 2013 Elsevier Ltd. All rights reserved. Source

Melendez M.E.,Estacion Enologica de Haro | Sarabia L.A.,University of Burgos | Ortiz M.C.,University of Burgos
Chemometrics and Intelligent Laboratory Systems

Biogenic amines are formed from precursor amino acids by various microorganisms present in wine, and this may happen at any step of production, ageing or storage. The presence of these compounds is important because high amounts of them can lead to health problems. Also, biogenic amines can be potentially applied as indicators of food spoilage and/or authenticity.Nevertheless, there are complex relationships among biogenic amines in Spanish wines and their distribution is far from a normal distribution. Even though, this structure must be taken into account to provide a frame of reference on the quality of wines and to contribute to the efforts of the entire productive chain to attain consumer safety.In this work, 684 samples of wines from different Spanish regions have been analyzed in order to determine the content of histamine, tyramine, phenylethylamine, cadaverine and putrescine during 2010, 2014 and 2015. The statistical distribution of histamine has been modelled by using the β-content tolerance intervals. Besides, copulas to obtain the joint multivariate confidence region between histamine and tyramine have been built for the first time in the oenological field. The β-content tolerance intervals for histamine content, in the case of the population of red wines in 2010, lead to decide that only 53.9% of the distribution would be below 10. ppm (with a 95% confidence in this affirmation). This percentage rises from 53.9 to 74.6% in the year 2014 and to 90.2% in 2015. Besides, the conjoint distribution of histamine and tyramine is modeled by a Clayton copula with margins estimated by Gaussian kernel, which allows concluding that this distribution is similar for the three years. © 2016 Elsevier B.V. Source

Melendez E.,Estacion Enologica de Haro | Ortiz M.C.,University of Burgos | Sarabia L.A.,University of Burgos | INiguez M.,Estacion Enologica de Haro | Puras P.,Estacion Enologica de Haro
Analytica Chimica Acta

The ripeness of grapes at the harvest time is one of the most important parameters for obtaining high quality red wines. Traditionally the decision of harvesting is to be taken only after analysing sugar concentration, titratable acidity and pH of the grape juice (technological maturity). However, these parameters only provide information about the pulp ripeness and overlook the real degree of skins and seeds maturities (phenolic maturity). Both maturities, technological and phenolic, are not simultaneously reached, on the contrary they tend to separate depending on several factors: grape variety, cultivar, adverse weather conditions, soil, water availability and cultural practices. Besides, this divergence is increasing as a consequence of the climate change (larger quantities of CO2, less rain, and higher temperatures).247 samples collected in vineyards representative of the qualified designation of origin Rioja from 2007 to 2011 have been analysed. Samples contain the four grape varieties usual in the elaboration of Rioja wines ('tempranillo', 'garnacha', 'mazuelo' and 'graciano').The present study is the first systematic investigation on the maturity of grapes that includes the organoleptic evaluation of the degree of grapes maturity (sugars/acidity maturity, aromatic maturity of the pulp, aromatic maturity of the skins and tannins maturity) together with the values of the physicochemical parameters (probable alcohol degree, total acidity, pH, malic acid, K, total index polyphenolics, anthocyans, absorbances at 420, 520 and 620. nm, colour index and tartaric acid) determined over the same samples. A varimax rotation of the latent variables of a PLS model between the physicochemical variables and the mean of four sensory variables allows identifying both maturities. Besides, the position of the samples in the first plane defines the effect that the different factors exert on both phenolic and technological maturities. © 2012 Elsevier B.V. Source

Discover hidden collaborations