ISO 9648:1988

Sorghum — Determination of tannin content

The method consists in extraction by shaking with dimethylformamide, then after centrifuging, addition of ferric ammonium citrate and ammonia to an aliqiot part of the supernatant liquid and spectrometric determination, at 525 nm, of the absorbance of the solution thus obtained, and determing of the tannic content using a calibration curve prepared using tannic acid.