Parallel factor analysis for monitoring data from a grape harvest in Qualified Designation of Origin Rioja including spatial and temporal variability

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. (C) 2015 Elsevier B.V. All rights reserved.