Quantitative analysis of inositol phosphate contents in oat products using an anion exchange chromatographic method

Noora Mäkelä,Tuula Sontag-Strohm,Miikka Olin,Vieno Piironen

doi:10.1016/j.jcs.2020.103121

Abstract

Oat has gained interest due to its high nutritional value. When utilising oat fractions rich in dietary fibre, their inositol phosphate (InsP, including phytate) content is considerably high due to the lack of active phytase in the kilned oat ingredients. The high InsP content is linked to decreased mineral absorption in the gut, but the mineral-binding ability of InsPs also results in antioxidativity and a decrease in starch hydrolysis, thus lowering glycaemic response. This study aimed to further develop an anion exchange liquid chromatographic method for quantification of different InsP forms from oat products and to study the changes in the InsP contents resulting from the differences in the ingredients or processes. The method was applicable for quantifying such InsP forms that can effectively bind minerals. The InsPs were stable at moderate temperatures and in the oat baking process, but a significant degradation occurred during the high-temperature treatments, extrusion, and bacterial fermentation.

Highlights

Interest in the use of oat as a food ingredient has increased during the past years
The separation efficacy was tested with the in-house reference (IHR), where a mixture of different inositol phosphates (InsPs) was produced in acid hydrolysis
Anion exchange chromatography was shown to be a suitable method for quantifying inositol phosphate forms that possess the mineral bind ing ability close to phytate and were called phytate-active forms

Summary

Introduction

Interest in the use of oat as a food ingredient has increased during the past years One reason for this is its high nutritional value; when compared to the other major food crops used in Europe, oat has a relatively high protein content, is gluten free, contains a high amount of lipids, and is rich in beta-glucan (Welch, 2011). In oat, a larger part of phytate stays intact as the oat pro cessing involves kilning where the grain material is moistened and heated to inactivate the lipases This process is a requirement for the prevention of oat, which is high in lipids, becoming rancid, but it simultaneously inactivates other enzymes, such as phytase

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Conclusion