Ceramic membrane cross-flow microfiltration for beer recovery from tank bottoms

Cross-flow microfiltration with ceramic membranes was applied for beer reco very from tank bottoms. The cross-flow microfiltration was optimised using model yeast suspension and the effects of pore size, flow speed and transme mbrane pressure were characterised, Using 200 mum pore-size membranes and b ack-flush in 5 min intervals during filtration of tank bottoms, filtration rate 20 kg/m(2) h(-1) compared to 3 kg/m(2) h(-1) without back-flush was ac hieved. The quality of beer recovered from tank bottoms was extensively eva luated. Increased values of some beer components were found in recovered be er when 200 mum membranes were used: bitterness increased from 20 to 36 deg rees EBC, total nitrogen from 78.4 to 172.1 mg/100 ml, polyphenols from 20. 4 to 56.4 mg/l and diacetyl from 0.11 to 0.41 mg/l. Pore-size in range 100- 500 mum has effect on filtration rate but no influence on beer quality. Som e parameters of recovered beer, such as extract, alcohol, pH are not change d. Analyse of 7 fractions collected during beer recovery showed that values are generally increased in last fractions.