Gluten Washing Tests
What are Gluten Washing Tests?
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.
Currently, two main gluten washing tests are available to bakers and millers:
- Manual or hand washing method. It provides a direct measurement of the gluten quantity.
- Automatic gluten washing, usually performed by an Glutomatic. This method provides information about the quantity and quality (strength) of flour.
How do Gluten Washing Tests work?
Manual or hand washing method1
The Cereals and Grains Association (AACC International) has standardized the manual gluten washing in the Official Method 38-10.01.
This test involves forming a dough and washing the starch and water-soluble components (e.g. water-extractable arabinoxylans, sugars, water-soluble proteins) out of the dough. A wet and elastic substance made of water-insoluble proteins (gliadins and glutenins, about 85% total protein) remains after the washing procedure whose amount is an indication of gluten quantity. The total wet or dry gluten (weight obtained after controlled drying of the wet gluten) is expressed as a percent.
Automated gluten washing (Glutomatic)2
AACCI has standardized this method in the Official Method 38-12.02 (Wet Gluten, Dry Gluten, Water-Binding Capacity, and Gluten Index). This is an automated procedure uses the Glutomatic instrument and includes a centrifugation step to dehydrate the gluten.
Here's how to preform the hand washing test, using the AACCI Official Method 38-10.01.1 Start with this equipment:
- Porcelain cup
- Spatula (for weighing and work dough)
- Petri dishes
- Convection oven
- Analytical balance
- US No.80 sieve
Ingredients and reagents needed:
- Wheat flours
- Water (tap)
Procedure (should be carried out in duplicate or triplicate for better results):
- Determine flour moisture content.
- Weigh 25 g flour into porcelain cup or mortar.
- Add tap water from a buret to form a dough. 50% water absorption is mostly used (0.5 g water / g of flour or 12,5 g water).
- Knead (work) 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...