Determination of d-myo-inositol phosphates in ‘activated’ raw almonds using anion-exchange chromatography coupled with tandem mass spectrometry

Abstract

BACKGROUND: Activated almonds are raw almonds that have been soaked in water for 12–24 h at room temperature, sometimes followed by a 24 h drying period at low temperature (50 ± 5 °C). This treatment is thought to enhance the nutrient bioavailability of almonds by degrading nutrient inhibitors, such as phytic acid or d-myo-inositol hexaphosphate (InsP6), through the release of phytase or passive diffusion of InsP6 into the soaking water. Over a wide pH range, InsP6 is a negatively charged compound that limits the absorption of essential nutrients by forming insoluble complexes with minerals such as iron and zinc. It is hypothesized that hydrating the seed during soaking triggers InsP6 degradation into lower myo-inositol phosphates with less binding capacity. RESULTS: Anion-exchange chromatography coupled with tandem mass spectrometry was used to quantify myo-inositol mono-, di-, tris-, tetra-, penta-, and hexaphosphates (InsP1–6) in raw pasteurized activated almonds. At least 24 h of soaking at ambient temperature was required to reduce InsP6 content from 14.71 to 14.01 µmol g−1. CONCLUSIONS: The reduction in InsP6 is statistically significant (P < 0.05) after 24 h of activation, but only represents a 4.75% decrease from the unsoaked almonds. © 2018 Society of Chemical Industry.