SOP: Determination of Gluten in Flour

GIFSQ — Global Institute for Food Safety & Quality

1. Principle

Gluten is the cohesiveness obtained by interaction of the water-insoluble proteins of wheat in the presence of water. Gluten is estimated by washing the dough, making it free from starch, sugar, water soluble proteins and other minor components.

2. Procedure

Weigh 25 g flour into a dish and knead with 15 mL water to make a dough ball

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Keep the dough ball immersed in water for 1 hour

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Remove the dough and wash the dough ball with a gentle stream of water over bolting silk cloth or muslin cloth

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Keep washing the dough ball until it is starch free — the water passing through the silk should not give a blue color with a drop of iodine

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Collect the residue, transfer to a watch glass or petri dish and keep it in the oven at 105 ± 1°C

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When partially dried, remove and cut into several pieces and again keep in the oven to dry till constant weight

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Cool in a desiccator and weigh

3. Calculation

Gluten (%) on dry weight basis = [Weight of dry gluten × 100 × 100] ÷ [Weight of sample × (100 − Moisture content)]

References

FSSAI Manual of Methods of Analysis of Foods, Cereal and Cereal Products (2016), part 8.5, Determination of gluten.