Victor Palacios

Comparative study of crossflow microfiltration with conventional filtration of sherry wines

Abstract The present work reports, firstly, on the application of the gel-polarisation model to the crossflow microfiltration of sherry wines and brandies, in order to calculate the model parameters. In a preliminary set of experiments, the influence of the transmembrane pressure (TP) on the filtrate flow was studied, at several feed flows. The obtained results show a constant ratio between the optimum TP (TPopt) and the feed flow of 32×10 −4 l h −1 Pa with a TPopt of 11×104 Pa, for a feed flow of 360 l h −1 for all products. The obtained values of D for the different products can indicate that the average size of the particles in the gel layer is from 10 to 50 nm. Secondly, it has compared crossflow microfiltration process with classic filtration processes, which are used in the standard production system. The results show that the microfiltration has a higher effectiveness than conventional filtration, except in the case of brandy, where conventional filtration is more effective.

Effect on White Grape Must of Multiflora Bee Pollen Addition during the Alcoholic Fermentation Process

The aim of the present study was to compare and analyze the impact of using bee pollen doses (0.1, 0.25, 1, 5, 10 and 20 g/L) as activator in the alcoholic fermentation process of Palomino fino and Riesling wines. In this regard, its influence on the musts composition, the fermentative kinetics, the evolution of the populations of Saccharomyces cerevisiae, the evolution of yeast-assimilable nitrogen and physico-chemical characteristics of final wines has been analyzed. Bee pollen addition produces significant increases in yeast-assimilable nitrogen and maximum yeasts population and exponential velocity reached during alcoholic fermentation. Bee pollen showed an important effect on yeast survival during the death phase. Final wines showed significantly increase in volatile acidity above doses higher than 10 g/L and Comisión Internacional de L’Eclairage parameters (CIELab), color intensity and Abs 420 nm, from 1 g/L. Therefore, pollen could be used as fermentative activator for the alcoholic fermentation of white wines applying doses below of 1 g/L.