Technological Study for the Evaluation of Brewing Raw Materials

Abstract

A brief review is made of the available carbohydrate raw materials and of the limitations of laboratory-or production-scale evaluation. A 30-brl( 5,000-1) experimental brewery was designed and built to facilitate adequate scientific control and to minimise differences of scale in the evaluation of selected raw materials. Wheat and barley flours and flaked barley were considered as possible substitutes for malt in the grist at levels of 10% to 25%. On technological and economic considerations wheat flour proved to be the most suitable mash-tun adjunct; the optimum level of usage was found to be 15% of the malt grist. Laboratory experiments indicated that the severe processing difficulties encountered when using 25% wheat flour could be overcome in a slurrying process. This work led to the finding that flour slurries might also be used for the preparation of syrups in the brewery. Analyses of traditional malt wort and flour-slurry enzyme hydrolysates showed encouraging correspondence in sugar and amino-acid spectra. Commercially available brewing syrups were also evaluated in the pilot brewery: wort syrups proved to be more attractive commercially than barley or green-malt syrups. (Wort syrups being derived from maize and wheat) The extraction efficiency of available extract from a traditional malt grist was ~ 97%. Although cost evaluation showed that sizeable savings can be made by using 15% wheat flour or 33% wort syrup in the grist, the Excise Duty levied on wort increases the cost tenfold; thus it is of paramount importance that maximum use is made of dissolved solids. The mass-balance of grist solids during wort preparation was therefore extended to the fermentation stage of beer production, and it was revealed that brewery utilisation of wort solids might be improved by making better use of dextrins, by using primings in place of residual wort sugars and by reducing yeast growth in various ways.