Preparation of a low carbohydrate beer by mashing at high temperature with glucoamylase

A malt grist, supplemented with glucoamylase (1,4-alpha -D-glucan glucohydrolase, EC 3.2.1.3), was mashed isothermally at 70 degreesC to produce wort with a real fermentability of over 87% and beer with a residual carbohydrate contents of less that 0.75% w/v at an original gravity of 42 degreesS. The effects of varying mash pH, calcium content, glucoamylase addition rate and mash conversion time were investigated. The process was effective even with undermodified malt. Pilot scale brewing trials showed no adverse effect on beer foam quality when th glucoamylase preparation had a specified range of protease side-activity. The process has the advantage of ensuring glucoamylase inactivation during wort boiling while being shorter than the alternative of enzyme treatment of wort prior to boiling.