Issue link: http://winesandvines.uberflip.com/i/840286
WINERY & VINEYARD EQUIPMENT 50 WINES&VINES July 2017 equipment is pore size, because selec- tion of the wrong membrane pore size can have a material effect on a wine's quality. Microfiltration: Equipment for microfiltra- tion almost universally uses the 0.2µ pore size. The polyethylene (PE) construction material has a very low affinity for anything in wine and has become the preferred material for microfiltration. For this reason, PE is a better compromise for the greatest permeate flux versus fouling the mem- brane from constituent particles. Ultrafiltration: From ultrafiltration (UF) downward, membranes separate their component parts based on a combination of molecular weight and effective molecular diameter, and the membranes are defined in broad areas of their theoretical and actual MWCO. At this level of molecular separa- tion, the term "dalton" is used for a unit expressing molecular weight of proteins. Ultrafiltration begins with membranes that separate compounds from 1,000 to 100,000 daltons. Membranes used in crossflow categories such as ultrafiltration are made to separate a relatively narrow range of compounds. For example, an ultrafiltration membrane rated 10,000 daltons would have an average MWCO from 9,500 to 10,500, meaning 100% of molecules less than 9,500 would pass, and some lesser amounts would pass up to 10,500. All compounds above that would be retained. The table of molecular weights of com- mon compounds found in wine shows that many compounds are smaller than ultrafiltration membranes should retain. Why, then, is it not used to clarify wine on a general basis? Aside from the fact that flux rates for normal clarification process- ing are terrible, ultrafiltration affects the structure and texture of wines by hinder- ing the three-dimensional aspects of the compounds. It also affects colloidal formation and waters of hydration that are found around larger polyphenols and other important wine compounds. These factors can make a compound seem larger than it actually is from a membrane transmission standpoint. UF can be used for concentra- tion of certain factors, but with care and a purpose. Do small-scale trials. Nanofiltration / reverse osmosis: These SCOTT LABORATORIES INC. SCOTT LABORATORIES LTD. (CANADA) The VLS crossflow system distributed by Scott Laboratories is a modular design. You can buy the system with cartridges and then add ad- ditional element cartridge loops as are needed up to nine cartridges. Each element is the typ- ical 10 m 2 of most suppliers. The nominal flow rates range from 1,135 liters per hour for the three cartridge unit to 3,406 liters per hour for the nine-cartridge unit. There is a feed pump with a pre-filter to protect the membranes from fouling with large particles. A digital flow meter and pressure sensor mon- itor inlet and outlet pressures. The programmable logic controller operates the basic parameters including flow rate, amount to filter and start/stop time. Options include a turbidity meter and an automatic cleaning option that controls the parameters for cleaning in place (CIP). This includes peristaltic pumps for measuring in the CIP materials and a temperature probe to assure the system does not overheat these materials. scottlab.com (U.S.), scottlabsltd.com (Canada) —continued from page 49