DETERMINATION OF INOSITOL PHOSPHATES IP3-IP6 IN RAPESEED AND RAPESEED MEAL BY AN HPLC METHOD .2. INVESTIGATIONS OF RAPESEED AND RAPESEED MEAL AND COMPARISON WITH OTHER METHODS

Because of their structure, phytic acid and its degradation products are able to bind other feedstuff ingredients, such as proteins, starch, cations or enzymes. This ability depends on the grade of phosphorylation. In order to investigate the influence of industrial processing on the inositol phosphate composition of rapeseed, 17 rapeseed samples and 8 rapeseed meal samples were analysed by an HPLC method. Only a small grade of degradation of IP6 was noticed both in rapeseed meal, where also IP4 could be determined, and in rapeseed. The results were compared with two other phytic acid determination methods. The precipitation method with FeCl3 of Wheeler and Ferrel and a photometric method were used for this comparison, both methods for determination of the sum of inositol phosphates. The results of the HPLC method and the method of Wheeler and Ferrel correspond in most cases, but the values or the photometric method are far higher.