Effect of Fibers Added During Pressure Leaf Filtration on the Membrane Filterability of White Table Wines

Abstract

Three fibers (CLR - cotton cellulose, uncharged; CLS - cotton cellulose, positively charged; and WCF - wood cellulose fiber, uncharged) were used as a precoat aid and as a precoat aid plus body feed aid during the pressure leaf filtration of commercial white table wine lots. Samples were taken during filtration and were tested for turbidity and membrane filterability. It was found that the measurement of turbidity was not a good indication of the filterability. Membrane filterability data, recorded as increments of time and volume, were used to develop resistance curves which were analyzed by the exponential filtration model of De La Garza and Boulton (3). These curves were used to compare the effectiveness of the fibers in improving the membrane filterability through pressure leaf filtration. The positive charge on the CLS, when used as a precoat aid, improved the membrane filterability of the initial filtrate, but the charge was depleted before the completion of the pressure leaf filtration. The addition of CLR or CLS as a body feed aid greatly improved the membrane filterability when compared to use of fiber as a precoat aid only. The best filterability was obtained with CLS in both the precoat and the body feed. Next best was CLS precoat with CLR body feed, and then CLR precoat with CLR body feed, and WCF precoat with WCF body feed.