Elemental Analysis of Tree Nuts and Their Pressed Oils by Triple Quadrupole Inductively Coupled Plasma-Mass Spectrometry (ICP-MS/MS)

Abstract

Trace elements in tree nut oils may be toxic for humans and catalyze the auto-oxidation of the oils, affecting their stability. These elements have not been comprehensively characterized. In this study, we prepared tree nut oils from tree nuts (camellia, acer truncatum, shiny leaf yellow horn, and pecan seeds, as well as walnuts and Brazil nuts) by cold-pressing and determined As, Cd, Cu, Fe, Mn, Pb, Se, and Zn in these seeds and their oils and residues. Moreover, we investigated the elemental migration from seed to oil. The migration of all measured elements from seed to oil was <2%, where Cu exhibited the lowest migration from 0.09 to 0.31%. Moreover, we studied the effect of preheating (25–150 °C) the seeds upon their elemental migration. The Cu, Fe, Mn, and Zn contents increased with the temperature in all tree nut oils. The migration of toxic As, Cd, and Pb did not significantly differ with temperature, suggesting that temperature does not affect the release of these elements from nuts to oil.