As barley is the cheapest source of starch and potentially of extract it is profitable to replace up to 70% of the malt by barley provided diastatic enzymes are added to assist conversion in the mash. In the use of Convertase 70 at 0.1% by weight of barley, mashing and lautering conditions in a large number of breweries were followed. The ground barley had a sieve analysis similar to that of a coarsely ground malt. Dry grinding as in an 'oat crimper' or a malt mill was satisfactory but for a Steinecker wet mill only a short presteep was necessary and then the barley was blended with the malt for milling. A mashing rate of 2.7 to 2.9:1 water:grain gave best results when all the grain and Convertase were mashed together. A typical mash cycle included rests at 45 degrees C, 65 degrees C and 72 degrees C before heating to 75 degrees C. Difficulty in lautering seldom occurred and could be corrected by mill adjustment. In some cases beer did not ferment to the desired attenuation limit and this was corrected by adding cold malt infusion to the cold wort after fermentation had begun and the pH was below 4.5. With over 80% replacement of malt, beers were lacking in character but 30% malt with barley and corn gave good flavour and improved head retention with better haze and colour stability than a control brew with 70% malt and 30% corn.
Keywords: additive adjunct barley brewing costs diacetyl enzyme malt mashing stability