Flavor and compositional analysis of macadamia nuts during long‐term storage

Abstract

The production of unpleasant flavor of macadamia nuts during long-term storage is a very common phenomenon in nut industry. Changes in volatile components were monitored by HS-SPME/GC–MS throughout a 9-month storage period to expound the unpleasant flavor of macadamia nuts. Aldehydes (primarily hexanal, heptanal, octanal, (E)-2-octenal, (2E)-2-nonenal, trans-2-decenal, nonanal, decanal, (E)-2-heptenal, and pentanal), and acids (mainly hexanoic and acetic acid) composed the main unpleasant flavor of macadamia nuts based on their concentrations, olfactory characteristics, and thresholds. Compositional analysis showed total lipid, fatty acids, and amino acids decreased by 6.35 g/100 g, 137, and 4.165 mg/g, respectively, after 9 months of storage. Besides, there was no kernel discoloration, while the AV and PV increased by 1.89 mg/g and 8.13 meqO2/kgOil, respectively. The flavor deterioration was induced by lipid oxidation and had little correlation with protein oxidation. Moreover, results of correlation and PLSR analysis demonstrated protein oxidation in macadamia nuts during storage were related to lipid oxidation. Novelty impact statement Unpleasant flavor composition was first identified based on sensory analysis and ROAVs of volatiles. Lipid oxidation of macadamia nuts induced flavor deterioration during storage. Changes in amino acids were closely related to lipid oxidation in macadamia nuts.