The Gluten Index method
Wet Gluten is prepared from whole meal or ﬂour by the Glutomatic 2200 gluten washer. Gluten Index Centrifuge 2015 is used to force the wet gluten through a specially designed sieve cassette. The relative amount of gluten passing through the sieve indicates the gluten characteristics.The wet gluten is further dried in the Glutork 2020 for dry gluten content and water binding in the wet gluten calculation.
The steps in detail
The steps are illustrated in the picture above. Click the picture to enlarge it.
10.0 g ± 0.01 g of whole meal or ﬂour is weighed and put into the Glutomatic wash chamber with an 88 micron polyester sieve. When vital wheat gluten is measured, 1.5 ± 0.01 g is weighed.
4.8 ml of salt solution is added to the meal or ﬂour samples. No salt solution is added to vital wheat gluten samples.
Meal or ﬂour and the salt solution are mixed to form a dough during 20 seconds.
After termination of the mixing phase, the washing automatically starts and continues for ﬁve minutes. For wheat meal the sample is transferred to a chamber equipped with a coarse 840 micron sieve allowing bran particules to be washed out.
Exactly 30 seconds after completed washing, the undivided wet gluten piece is transferred to the special sieve cassette and centrifuged one minute at 6000 ± 5 rpm in Centrifuge 2015.
The fraction passed through the sieves is scraped off with a spatula and weighed. The fraction remaining on the inside of the sieve is collected and added to the balance. The total wet gluten weight is obtained.
The total wet gluten piece is dried at min. 150°C during four minutes in the Glutork 2020. After drying the gluten is weighed on the balance.
The amount of gluten remaining on the centrifuge sieve in relation to total wet gluten weight is the Gluten Index.