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Lees Filtration & Alcohol Recovery from Yeast Bottoms


Cider Producers Maixmize Yield and Increase Quality With the Oenoflow™ HS System

Lees, the sediment at the bottom of juice, fermentation or maturation vessels, still contains a high percentage of recoverable cider. The Oenoflow™ HS system is a new crossflow filtration system designed specifically for lees processing. The hollow fiber system overcomes the typical drawbacks associated with the existing Diatomaceous Earth (DE) based lees filters, producing higher quality product more efficiently and economically.


Filtration is a key operation in modern cider production to deliver visually bright and shelf stable product. Traditionally, cider clarification has been performed with diatomaceous earth or sheet based filtration technologies. However, with more favorable economics, easier operation and lower waste volumes, crossflow filtration systems like Pall’s Oenoflow™ XL system have become more widely adopted.


While the aforementioned clarification systems can concentrate to high solids levels, there is still a significant amount of recoverable alcohol in the yeast at the bottom of fermentation or maturation tanks and filtration system concentrates. With Pall’s newest member of the Oenoflow family of systems, the HS system, cider producers can now recover high quality cider from these lees streams to gain up to 4% capacity with no additional capital investment.


The Oenoflow HS system design incorporates diafiltration, a process where water is added to the lees concentrate. Diafiltration “washes out” alcohol from the yeast to increase recovery and improves the return on investment. The resulting alcohol strength of the filtered cider batch is reduced, however, this helps to lower the water required for the downstream blending to bottle strength.


OenoFlow HS Filtration System

The Oenoflow HS system is a crossflow filtration system for lees filtration that overcomes many of the obstacles associated with the traditional DE based technologies. Filtration is achieved with microporous membranes without the need for filter aids. With no powder handling, operation is more hygienic and does not create DE waste for environmental landfill.


Wide bore hollow fibers permit processing of lees with high solids levels. A high yield product can be recovered as the retained solids reach final concentrations up to 80%. The polyvinylidene difluoride (PVDF) membranes have a uniform structure that guarantees resistance to abrasion and high flow rates without compromising reliability even with repeated cleaning regimes. The low system hold up volume and batch operating mode allows small volumes of lees to be filtered immediately after racking in order to maintain optimal quality in the recovered product.


In addition to the operational and environmental benefits, the Oenoflow HS system also provides significant product quality benefits. Unlike the open DE systems, the enclosed system minimizes oxygen pick up and maintains the color, aroma, acidity and flavor characteristics. Recovered product can be added back to the original batch at a significantly higher value than the cider recovered from RVD and chamber filters which is often blended into lower quality, lower priced product. This added value is reflected in short system return on investment with typical payback in the range of 1 to 3 years.


In addition to lees filtration, the system can also be used for post fermentation clarification expanding overall capacity. With these combined capabilities, the Oenoflow HS system has the flexibility of three systems in one.