Chapter 9

Wort Separation

Mash Filter

Although lauter tuns are widely employed for wort separation, some large-volume brewers prefer mash filters and where throughput and floor space are priorities. Mash filters are very much like plate and frame filters consisting of a series of grid-type plates alternating with hollow frame plates that are suspended on side rails (Figure 9.6). Each grid plate of the filter is covered on both sides with a monofilament polypropylene cloth. Alternate plates are equipped with elastic membranes which can be inflated with compressed air to squeeze the mash against a permeable polypropylene cloth. Accordingly, the grist serves no purpose as a filter medium and their particle sizes are of no consequence.

Filtration Process

To initiate the wort separation cycle, the mash filter is flushed, then preheated with hot water. The filtration cycle starts with pumping mash into the bottoms of the filter frames. As the mash enters, the pressure drives wort through the filter pads to runoff channels behind them. If the filter is under-filled, the efficiency of the extraction process suffers significantly because the sparge water will flow through the empty portion of the chamber (Stewart et al., 1985). Overfilling, on the other hand, results in excessive density, adversely affecting filtration efficiency (Stewart et al., 1985). When all wort is transferred, the mash valve is closed, and the membranes are inflated with compressed air, driving wort from the grain and through the filter cloths.

Meura 2001 Filter

In the competition for yield and brew frequency between lauter tuns and mash filters, a new generation of high-pressure filters (e.g., Meura 2001) was introduced to the market.

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