SOP: Determination of Starch Content — Spices

GIFSQ — Global Institute for Food Safety & Quality

Reagents

1. Ethyl ether
2. Ethyl alcohol 10% (v/v)
3. Dilute hydrochloric acid — 2.5%, prepared by mixing 20 mL of conc. HCl (sp. gr. 1.12) with 200 mL water
4. Sodium carbonate solution — 20% (w/v)

Procedure

Extract about 3 g of the ground sample, accurately weighed, with five 10 mL portions of ether on a filter paper that will retain completely the smallest starch granules

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Evaporate the ether from the residue and wash with 150 mL of 10% ethyl alcohol. Carefully wash off the residue from the filter paper with 200 mL of cold water

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Heat the undissolved residue with 200 mL of 2.5% dilute HCl in a flask equipped with reflux condenser for two and half hour. Cool and neutralize with sodium carbonate solution and transfer quantitatively to a 250 mL volumetric flask and make up to volume

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Determine reducing sugars in the solution by Lane and Eynon volumetric method using Fehling solution and methylene blue as internal indicator. Express the result as dextrose

Calculation

Starch content = Dextrose × 0.9

References

FSSAI (2016), Manual of method of analysis of foods — spices and condiments; Method no 16.5.