FEASIBILITY OF CONTIMUOUS MAIN FERMENTATION OF BEER USING IMMOBILIZED YEAST

4 3 0 V T T P U B L I C A T I O N S Ilkka Virkajärvi Feasibility of continuous main fermentation of beer using immobilized yeast P P TECHNICAL RESEARCH CENTRE OF FINLAND ESPOO 2001 VTT PUBLICATIONS 430 Feasibility of continuous main fermentation of beer using immobilized yeast Ilkka Virkajärvi VTT Biotechnology Dissertation for the degree of Doctor of Science in Technology to be presented with due permission for public examination and debate in Auditorium KE 2 at Helsinki University of Technology (Espoo, Finland) on the 9th of March, 2001, at 12 o`clock noon. TECHNICAL RESEARCH CENTRE OF FINLAND ESPOO 2001 ISBN 951–38–5840–5 (soft back ed.) ISSN 1235–0621 (soft back ed.) ISBN 951–38–5841–3 (URL: http://www.inf.vtt.fi/pdf/) ISSN 1455–0849 (URL: http://www.inf.vtt.fi/pdf/) Copyright © Valtion teknillinen tutkimuskeskus (VTT) 2001 JULKAISIJA – UTGIVARE – PUBLISHER Valtion teknillinen tutkimuskeskus (VTT), Vuorimiehentie 5, PL 2000, 02044 VTT puh. vaihde (09) 4561, faksi (09) 456 4374 Statens tekniska forskningscentral (VTT), Bergsmansvägen 5, PB 2000, 02044 VTT tel. växel (09) 4561, fax (09) 456 4374 Technical Research Centre of Finland (VTT), Vuorimiehentie 5, P.O.Box 2000, FIN–02044 VTT, Finland phone internat. + 358 9 4561, fax + 358 9 456 4374 VTT Biotekniikka, Prosessitekniikka, Tietotie 2, PL 1500, 02044 VTT puh. vaihde (09) 4561, faksi (09) 455 2103 VTT Bioteknik, Processteknik, Datavägen 2, PB 1500, 02044 VTT tel. växel (09) 4561, fax (09) 455 2103 VTT Biotechnology, Process Technology, Tietotie 2, P.O.Box 1500, FIN–02044 VTT, Finland phone internat. + 358 9 4561, fax + 358 9 455 2103 Cover picture: SEM micrograph by Paula Raivio, VTT Building and Transport Technical editing Leena Ukskoski Text preparing Arja Grahn Otamedia Oy, Espoo 2001 Virkajärvi, Ilkka. Feasibility of continuous main fermentation of beer using immobilized yeast. Espoo 2001. Technical Research Centre of Finland, VTT Publications 430. 87 p. + app. 50 p. Keywords beverages, beer, brewing, primary fermentation, immobilized yeasts, carriers, stability, flavours, microbes, contamination Abstract Fermentation is the most time consuming step in the production of beer and therefore the effective use of fermentation vessels is a crucial element in brewing economy. One means of increasing the productivity of a batch process is to convert it to a continuous one. Experiments in continuous fermentation emerged during the 1950s and 1960s, but by the end of 1970s most of them had been closed down. Immobilization technique revitalised continuous fermentation research in the 1980s and led to industrial applications in the secondary fermentation and in the production of low-alcohol beers. This work demonstrated that an immobilized, continuous main fermentation is a feasible process for production of lager beer. The immobilized main fer-mentation was stable for more than 14 months both in fermentation efficiency and in aroma compound formation. The formation of aroma compounds could be controlled by varying the composition and amount of gas feed into the first fermentation stage. The division of immobilized main fermentation into an aerobic and an anaerobic stage appeared to solve problems related to yeast growth and viability. The carrier material affected the formation of flavour compounds in small-scale fermentations. Moreover the effect varied with the yeast strain used. The carrier affected the economy of immobilized fermentation: the carrier cost could be as high as one third of the investment. When a cheap carrier is used the investment cost for a continuous, immobilized process was estimated to be only about 70% of the investment cost of a batch process. 3 ... - tailieumienphi.vn