Search: monitoring brewery grist

The extract yield in the brewhouse is highly dependent on optimal milling of the malt or other grain. The composition of the brewery grist should therefore be monitored on a regular basis.

The sieve analysis is performed on a sample of brewery grist of a known weight with a shaking device containing a set of sieves (according to DIN ISO 3310-1 specifications or a Pfungstädter plansifter sieving device).

The sieve analysis is performed on a sample of brewery grist of a known weight with a shaking device containing a set of sieves (according to DIN ISO 3310-1 specifications or a Pfungstädter plansifter sieving device). The material retained on sieve 1 is then poured into a 500 ml graduated cylinder and the volume (without shaking) is read on the graduated cylinder.

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.

The hot break material (trub) and any hop particles which may be present in the wort, must first be removed. After the wort has been cooled to 2 °C, it is filtered through a glass fiber filter. The residue remaining on the filter is dried and then weighed.

Cold break material or cold trub refers to all material that settles out in the process of chilling wort after separation of the hot trub or hot break material. Cold trub can be filtered out of the wort and primarily consists of proteins (48–57 %), tannins (11–26 %) and carbohydrates (20–36 %). The amount of cold break material in wort depends on the quality and composition of the raw materials, brewhouse equipment and wort handling. In academic and professional circles, opinions regarding the significance of cold break material for downstream processes and for the quality of the finished beer are strongly divided [1, 2, 5]. Under certain circumstances, the quantity of cold break material in wort may exceed 250 mg/l, especially where accelerated fermentation is practiced. Ultimately, this can detract from the flavor of the finished beer [3]. Breweries, where removal of the cold break material has been practiced successfully, determine the quantity of cold break in their pitching wort at regular intervals, in order to evaluate the efficacy of their separation equipment.

Malt is ground between two horizontally positioned, grooved discs. The lower disc is driven by an electric motor and rotates at approx. 1500 rpm; the upper disc is fixed and therefore does not move. During the milling process, the malt migrates from the center of the discs to the outer edge, where the grist falls through an outlet spout into a grist beaker.

The gap between the discs can be adjusted by turning a socket head screw on a calibrated ring bearing scale markings. The scale on the calibrated ring ranges from 0 to 20, with each scale division corresponding to a gap between the discs of 0.10 mm. Each scale division is subdivided into five smaller divisions; each of the smaller marks is equivalent to 0.02 mm. Two gap adjusting rings ensure reproducible mill settings.

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.