Collection of a representative sample of spent grain
Spent grain
A representative sample is required for monitoring brewhouse operations by means of a spent grain analysis. To achieve this, samples of an identical size are collected from the spent grain conveyor at the same time intervals.
Determination of the degree of proteolysis during mashing
Congress mash, cast-out wort
Mashing intensity provides information about the degree of proteolysis during the mashing process and is calculated as the quotient of the nitrogen content of brewery wort and the nitrogen content of Congress wort. It can be used to compare different mashing methods. An increase in mashing intensity usually corresponds to an increase in brewhouse yield.
A test for starch conversion with the iodine reaction
Congress mash, mash, wort
Higher molecular weight starch degradation products react with iodine after precipitation with alcohol. The reaction between iodine and starch results in the formation of an inclusion-type compound, evident by a change in color.
Measuring the turbidity during the lautering process
Lauter wort, wort
If a beam of light strikes a particle with a diameter larger than the wavelength of the light, the light is scattered. In measuring turbidity during the lautering process, it has been shown that only light scattered in a forward direction should be measured to achieve a meaningful correlation between the concentration of solids and the measurement value. Measurements performed at a 90° angle do not correlate with the amount of solids in wort due to particle size and dependence on color. Measurements performed at a 12° angle not only measure the amount of scattered light, but also the absorption (light transmission). The utilization of dual light beams eliminates disruptive factors, such as color, the age of the lamp and window fouling.
Measuring the turbidity during lautering serves to monitor and control lauter bed cutting operations and recirculation of the turbid wort as well as the quality of milling and mashing processes. There is a direct relationship between the turbidity profile during lautering, the results of the photometric iodine test and the solids content of the lauter wort.
Determination of the moisture content in the spent grain
Spent grain
The moisture content is determined by means of the loss in mass during a standardized drying process. For this purpose, the spent grain is dried at a defined temperature over a set time in an electrically heated air drying oven. The moisture content is determined by the difference in weight before and after drying.
If the barley possesses a moisture content of more than 17 % w/w, the whole kernels shold be dried prior to grinding them and determining the moisture content in the (coarsely ground) spent grain. The moisture content of the finely ground spent grain is subsequently determined and the total moisture content calculated from both values.
The compounds in the malt dissolved in the mash liquor during a standardized mashing process using finely ground malt (fine grist) are determined in this analysis.
Malt intended for use in beer brewing or elsewhere in the food industry
The Congress mash method primarily serves to determine the extract content of malt.
The extract content is determined by the weight ratio sL 20/20 of the wort on the basis of the official sugar tables (Plato tables) at 20 °C. sL 20/20 stands for the weight ratio of a volume of wort at 20 °C to the same volume of water at the same temperature.
Furthermore, the following is tested over the course of this analysis: Iodine test (saccharification time), odor of the mash, wort run-off, clarity of the filtered wort; the Congress wort is also used as a basis for a wide variety of further analyses.