Description
This method describes the quantitative determination of hydroxyproline and the estimation of the amount of collagenous connective tissue in meat and meat products. In 1987, eighteen laboratories participated in a collaborative study, using a colour reagent dissolved in perchloric acid. Estimates of the reliability of the method, repeatability and reproducibility, are described in paragraph 9.3. In this revised method, a description of a colour reagent dissolved in sulphuric acid is also included, see paragraph 5.4.2. The use of this colour reagent is recommended, see 9.3. The sample is hydrolysed in sulphuric acid at 103°C, filtered and diluted. Hydroxyproline is oxidised with chloramine-T. After the addition of 4-dimethylamino-benzaldehyde, a red- purple colour is developed, which is measured photometrically at 558 nm.