Determination of the concentration of carotenoids and provitamin A
This method is suitable for NAB and juice.
The carotenoids are extracted with a solvent. The total carotenoid content in this solution is determined photometrically. After dissolving in ethanol, the content of β-carotene and α-carotene is determined using HPLC through separation on a C30 phase. The vitamin A content is then calculated.
Determination of the content of provitamin A
This method is suitable for the analysis of non-alcoholic beverages and juices which do not contain any other carotenoids except for β-carotene.
Carotenoids soluble in petroleum ether are clarified using Carrez I and Carrez II solutions and precipitated quantitatively through adsorption with zinc hexacyanoferrate (II) . The carotenoids in the precipitate material are dissolved in acetone and subsequently extracted with petroleum ether. The total carotenoid content in the petroleum ether solution is determined photometrically.
Determination of the content of provitamin A
Suitable for non-alcoholic beverages, juices
Carotenoids present in the juice sample are precipitated with the Carrez reagent. Interference substances remain in solution and are decanted. The Carrez precipitate is extracted with tetrahydrofuran and acetone followed by photometric determination. The extract is analyzed by means of HPLC for precise analysis of the carotenoids.