Extraction and Assay of Acetic Acid Esterase From Malted Barley*

The extraction and the assay conditions for acetic acid esterase from barley malt have been optimised. An assay method was developed using diacetin as a substrate. The presence of reduced glutathione and the detergent Triton‐X‐100 in the extraction medium improved the yield of enzyme. The optimal pH for extraction was 8.0. When malt extracts were held at various temperatures acetic acid esterase was denatured at temperatures above 30°C. The optimum pH when measuring activity was 7.0. The crude enzyme extract released acetic acid from both soluble and insoluble cell wall materials. An insoluble, active form of the enzyme remained in the residual grain solids after the soluble form had been extracted.