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Separation and identification of the protein (hordein) fraction of barley or barley malt by means of gel electrophoresis. The method is suitable for all types of barley, as long as reference substances are available. However, the method cannot be used to identify barley varieties used to produce malt that has been so strongly modified that the protein fraction is almost completely degraded.

The aliquot of an extract of malt is added to a buffered starch solution and allowed to stand for exactly 30 min at 20 °C. Then, the maltose – formed primarily from the starch through the action of the β-amylase – is measured using iodine and is determined according to the following chemical reaction:

Using a buffer solution, malt extract is produced, and then under defined conditions the extract is incubated on a specific substrate of BPNPG7 oligosaccharide (a p-nitropheny-maltoheptaoside blocked at the non-reducing end) in the presence of thermostable α-glucosidase. The α-glucosidase is initially unable to degrade the "blocked" oligosaccharide. Only when the oligosaccharide is hydrolyzed by the activity of the α-amylase (an endoenzyme) from the malt are the resulting fragments vulnerable to the enzyme. Then, they are quantitatively degraded to glucose and free p-nitrophenol by the α-glucosidase, which is present in excess.

Adding a weakly alkaline solution halts the enzymatic activity and simultaneously induces a color reaction. The absorbance measured at 400 nm is proportional to the activity of α-amylase in the sample.

While α-amylase is active in a gelatinized solution of amylopectin, the viscosity of the solution is constantly dropping due to the degradation of the starch molecules, which can be tracked using a rotational viscometer. The change in the reciprocal of the specific viscosity serves as a measure for the activity of α-amylase.

Using a buffer solution, malt extract is produced, and then under defined conditions the extract is incubated on an azo-barley glucan substrate. The substrate is coupled with an azo dye, which is degraded by the β-glucanase activity to form low-molecular weight fragments. After addition of the precipitating agent, these fragments stay in solution and can be spectrophotometrically determined in the supernatant after centrifugation. The absorbance in the supernatant depends directly upon the activity of the β-glucanase in the analyzed malt.