Abstract 033
Filtration Difficulties Resulting from Damage to Yeast During Centrifugation
Tech. Quart., Master Brew. Assoc. Am. 24: 1-8, 1987
K.J. Siebert, L.E. Stenroos, D.S. Reid, and D. Grabowski
Occasional poor clarification during lager storage resulted in poor final pulp filtration performance. Investigation of the haze material indicated that a significant portion of it was derived from yeast cells. It was discovered that some of the yeast was fractured upon centrifugation in disc centrifuges at the end of fermentation. The effect is probably caused by mechanical forces in the disc centrifuge, as several times higher g-forces in a laboratory bucket centrifuge caused no measurable cell damage. A study of the centrifuge operation showed that faster centrifuge feed rates resulted in a smaller % of cell wall fragments, apparently because of a shorter residence time. Another model disc centrifuge, which produced higher g-forces, resulted in larger amounts of cell breakage. Nozzle and desludger centrifuges appeared to produce similar amounts of cell damage.
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