Wines requiring the removal of yeast and bacteria, which include sweet non-fortified wines, usually undergo a further filtration step immediately prior to bottling. A sheet filter equipped with XE400, XE675H, XE900H or XE1200H polishing or sterilising sheets is used. Again, Carlson has developed these sheets with carefully controlled pore sizes to ensure excellent sterilisation characteristics. A typical flow rate here is 350 litres per square metre per hour.
There are a number of specialist applications related to wine production including:
Brandy is normally filtered in one stage, particularly to remove metal hazes using XE 90H sheets.
Champagne also uses single stage filtration under high pressure using XE200H sheets.
Liqueurs are normally prepared by macerating various herbs in the base spirit and these are removed by straining. Filtration usually follows this step to remove fine colloidal turbidities using sheets from the BK series. At the bottling stage, final polishing is achieved using XE150H or XE200H sheets.
Sherry is usually filtered in one stage using medium clarifying sheets such as Carlson's XE90H.
Fortified wines and wine based aperitifs are usually filtered using sheets from the BK series.
Both malt and wine vinegars are filtered at the bottling stage. Pre-filtering is carried out, typically using XE90H clarifying sheets at 200-550 litres per hour per square metre, depending on the quality of the raw vinegar. Final filtration is primarily carried out to sterilise and polish the vinegar using XE400H sheets at 300-350 litres per hour per square metre.
