ed the “wort” When the mashing is completed, the spent raw material, called the “spent grains”, is separated from the wort by straining. The wort is then boiled with hops or hop extracts, releasing bitter substances and oils which are dissolved in the wort. During boiling the bitter substances are isomerizes, which increases their solubility, and a precipitate consisting mainly of proteins is obtained (the “trub’). After separation of the trub, the wort is cooled to approximately lO0C. The cooled wort is transferred to the fermentation area.MillingIn order to obtain a high yield of extracted substances as quickly and efficiently as possible, the malt must first be crushed before being mixed with hot water. Care should be taken during crushing to make sure the husks are not damaged, since they are used as filter bed for separating the spent grains when straining off the wort.Since the extract yield generally increases in direct proportion to the degree of fineness to which the malt is milled, it would be preferable for the malt to be crushed to very fine flour. However, this would cause the filter bed to become clogged during most wort straining operations, resulting in an increase in the time required for separation. Moreover, the bed would become less permeable, leading to the hold-up of valuable extract within the spent grains. Spargin2, if used, would also be less effective in recovering extract. The fineness to which the malt is milled is therefore a balance between best extract yield and ability to filter the wort.MashingMalt MashThe purpose of mashing is to obtain a high yield of extract (of the highest possible quality) from the malt grist and adjuncts by extraction in the brewing water. Only a minor part of the extract is obtained through ordinary dissolution, while the remainder is extracted by means of the enzymatic breakdown of complex insoluble substances to simple water-soluble substances...
