title: Impedance technology reduces the enumeration time of Brettanomyces yeast during beer fermentation.
abstract: Brettanomyces yeasts are increasingly being used to produce lambic style beers and craft beers with unique flavors. Currently, the industry monitors Brettanomyces bruxellensis using time consuming plate counting. B. bruxellensis is a fastidious slow growing organism, requiring five days of incubation at 30°C for visible growth on agar plates. Thus, a need exists to develop a quicker, feasible method to enumerate this yeast. The aim of this study was therefore to determine the feasibility of using the 'direct' and 'indirect' impedance methods for the enumeration of B. bruxellensis in beer and to monitor the growth of the yeast during fermentation. The impedance methods were able to decrease the incubation time of beer samples containing Brettanomyces from 120 h down to 2 and 84 h for samples containing 107and 103cfu/mL, respectively. The 'indirect' method was more successful than the 'direct' method, presenting a smaller error and wider detection range. Overall, the 'indirect' impedance method is a viable alternative to plate counting for the enumeration of yeasts in the brewing industry because it decreases preparation and incubation times, thereby increasing throughput and decreasing the chance of contamination.
authors: Department of Chemical and Materials and Engineering, University of Auckland, Auckland, New Zealand.
authors: Sanelle
authors: S
authors: van Wyk
authors: Department of Chemical and Materials and Engineering, University of Auckland, Auckland, New Zealand.
authors: Filipa V M
authors: FV
authors: Silva
mesh_terms: D001515:Beer / Q000382:microbiology*; D055168:Brettanomyces / Q000254:growth & development* / Q000378:metabolism; D002138:Calibration; D017097:Electric Impedance; D005285:Fermentation; D005516:Food Microbiology / Q000379:methods*
keywords: Analytical method; Brettanomyces bruxellensis; Dekkera bruxellensis; Enumeration; Fermentation