Membrane filtration preparing wines

The vast majority of Washington wine is filtered through nonasbestos filter pads. In preparing the wine for bottling, the S02 levels employed will vary depending upon whether or not the winery utilizes membrane filtration and/or some other form of wine sterilization. One major winery bottles its wine at 35 mg/L free S02 with the addition of200 mg/L of sorbate followed by a membrane filtration. Many of the small wineries lack a source of steam or... 

Membrane filtration is used at the time of bottling, mainly in cases where sterile, or at least low-microbe bottling is required (Section 11.3.4). The wine must have been properly prepared so that this operation can be run at a satisfactory flow rate, without excessive clogging. 

Analysis is performed on the acidified sample prepared by addition of 0.5 mL H3P04 1 M to 4.5 mL of wine and filtration on membrane 0.45 xm. The HPLC conditions used are the same reported for skins extract. 

Wine peptides are normally analyzed after a preparation step allowing their separation from the high MW components, mainly proteins and polysaccharides. This is achieved by ultrafiltration on membranes with appropriate cut-off and/or by gel filtration (e.g. on Sephadex LH-20 or G-10 gels) (Desportes et al., 2000 Moreno-Arribas et al., 1996 and 1998) of concentrated samples. This allows the isolation of one or more peptide fractions by removing the interfering compounds with different MW, such as salts, amino acids, phenols, organic acids and sugars. 

The simplest sample preparation processes for FIA determination are the ones for beverages. For fluorimetric determination of histamine in wine and cider using an anion-exchange column-FIA system, the samples only required appropriate dilution with hydrochloric acid and degasification in the case of cider, followed by filtration through a 0.22-pm nylon membrane microfilter to retain microparticulate matter (mainly tannic compounds) (del Campo et al., 2006). 

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