The Biological Impact of Flash Pasteurization Over a Wide Temperature Interval*

Abstract

Trials on the impact of flash pasteurization on beer quality showed that higher pasteurization temperatures with shorter holding times are favourable for beer quality. However, the killing effect in the temperature range up to 90°C has not been elucidated so far. Pasteurization temperatures of 50°; 60°; 72°; 84° and 90°C and pasteurization units of 0; 15; 80 and 500 PU were used. The associated residence times were calculated according to Del Vecchio et al.'s formula. The experiments with beer-relevant yeasts and bacteria showed that Saccharomyces yeasts are much easier to inactivate than Lactobacilli and Pediococci. Furthermore, it can be stated that the commonly used PU calculation according to Del Vecchio reflects the actual killing characteristics in the temperature range from 60° to 72°C quite precisely. Although flash pasteurization with low PU figures at temperatures higher than 72°C and with very high amounts of bacteria may be insufficient, because the real inactivation effect is lower than indicated, there is no need to increase the PU load when changing to higher pasteurization temperatures and shorter holding times in practical application.