Gluten washing tests are laboratory analyses that provide information about the quantity and quality of gluten in wheat flour. These tests are used to evaluate the baking quality of hard and soft wheat flours used in the production of bakery products. The procedure to measure gluten is quite easy but a tedious job. An overview of the workflow is provided below.
Weigh 25 g flour into porcelain cup or mortar.
Add tap water to form a dough. 60% water absorption is mostly used
Knead the dough by hand until a firm to medium consistency dough ball is obtained
Submerge the dough and soak with sufficient water in a beaker for 20-60 min at room temperature. Washing efficiency of hard wheat flours is improved with increased soaking time and temperature. Soft wheat flours are easier to wash if soaking time does not exceed 20 min
Knead dough gently (massage) while using wash water and replace with fresh water until starch and all soluble matter are removed. When much of the starch has been removed, the gluten ball will become darker and more elastic. This step usually takes 15–80 min and the time depends on the gluten content and wheat hardness
A cloth or sieve can be used to collect scattered gluten pieces lost in the wash, especially in the case of soft wheat. NaCl can be added to the soaking and wash water to handle soft wheat dough’s
To determine whether gluten is starch-free, squeeze the gluten mass and let 1 or 2 drops fall into a beaker containing clear water. If starch is still present, it will make the water cloudy
When the gluten mass is finally clean, press it between the hands and roll into a ball. Remove excess water by working the mass until it just begins to stick
Take the weight of wet gluten and note down
Transfer gluten ball to dry to constant weight and allow to cool down for approximately 15 minutes
Take weight of the dry gluten and note downWe use the following calculation to determine the gluten percentage in wheat
Wet gluten = wt. of wet gluten/samples wt. X 100%
Dry gluten = wt. of dry gluten/ sample wt. X 100%
ASRBC, ACI Seed