Pumping yeast in wineries with a peristaltic pump

The process of fermentation:

Winemaking or vinification starts with the selection of grapes. After harvesting the grapes, they are taken to a winery for fermentation. Red grapes are made from the pulp fermented along with the skin, which gives it the real colour. Whereas white wine is made by fermenting the juice extracted from the grapes.

Traditionally the grapes were collected in oak vessels for fermentation. Nowadays, many wineries adopt a more modern approach of fermenting in Stainless Steel containers open at the top.

During this stage yeast may be added to catalyse the fermentation process. This usually takes one to two weeks during which the yeast converts sugar in the grapes into alcohol. The alcoholic fermentation takes place in the favourable conditions created by pumping over the mixture and pigeages (traditional stomping of grapes), along with the addition of yeast.

At the end of the process, yeast is removed to avoid spoiling of flavor and to leave the wine with a clear, crisp appearance.

Verderflex hose pumps in the filter press:

The process to remove yeast is usually performed by introducing diatomaceous (kieselguhr) earth into the fermented wine. The fine particles of diatomaceous earth attract the yeast cells to form clumps, which remain in a suspension referred to as yeast slurry. The yeast slurry is then pumped through a filter press with a Verderflex peristaltic pump, before the wine is finally stored or bottled.

A German company manufactures chamber filter press system mounted on a skid with a Verderflex VF25 industrial hose pump as part of a standard filter press system.

From the yeast slurry storage vessel, the slurry is fed into the peristaltic pump through a 32-mm suction line made from flexible Verderflex hose to reduce pulsation. The peristaltic Verderflex pump is fitted with DIN 11851, type SC stainless steel sanitary connections of 32 mm, with reducing inserts to suit the 25mm tubing. The drive of the pump is a 1.1 kW gear reducer giving a pump speed of 48 rpm, delivering 800 l/hr of product to the filter press.

On the discharge side of the filter press pump, a 32mm flexible hose is used to feed the filter press. It is important to eliminate the pulsation on the discharge side of the peristaltic pump, so in addition to the flexible hose, an air dome is installed. The air dome has a volume of approximately 20 liters, allowing it to absorb pulsation, but also to act as a pressurized storage tank for the filter.

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