Search: spent grain

High molecular weight dextrins and starch present in the wort extracted from brewery spent grain are precipitated through the addition of ethanol, centrifuged and dissolved in phosphate buffer, followed by the addition of an iodine solution. Depending on the molecular weight and degree of branching, a red to blue color forms, the intensity of which is measured spectrophotometrically at 578 nm.

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.

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.

Wet spent grain is pressed using a manual press.

The soluble extract in the spent grain is determined by rinsing with H₂O at 70 °C.

The total extract is obtained through boiling the spent grain followed by enzymatic digestion with technical enzymes (Termamyl 120 L and SAN Super 360 L). The available residual extract represents the difference between total extract and soluble extract.