Monitoring the quality of γ-irradiated macadamia nuts based on lipid profile analysis and Chemometrics. Traceability models of irradiated samples

Macadamia ( Macadamia integrifolia ) is an edible nut species with commercial importance in cosmetic and pharmaceutical industries due to its high concentration in monounsaturated fatty acids and its low cholesterol levels. γ-Irradiation is a food processing procedure that allows the extension of shelf life and is broadly applied to dry nuts. Therefore there is an increasing research interest towards the development of new methods and markers for the detection of irradiated food items. In the present article, 60 Co-irradiation was applied to macadamia nuts in increasing doses up to 10 kGy using different packaging and storage conditions in order to monitor changes in their lipid profile. Compositional data showed predominance of triglycerides followed by phytosterols in a much smaller proportion in nuts' lipids. The production of hydrolytic compounds as a result of gamma irradiation was statistically significant but didn't affect the macadamias' fat quality. Classification was achieved in relation to irradiation dose, package and storage conditions, using Chemometrics. More specifically, PCA and OPLS-DA analyses on the GC–FID, TLC–FID and color results managed to differentiate samples according to irradiation doses. NMR based FoodOmic application is employed for the first time, in order to explore any trends in sample classification according to the irradiation dose and the storage or the packaging effect. Minor lipid components (such as β-sitosterol, C18:2 n − 6, C18:3 and sn1,2 and sn1,3 DGs) have shown high discriminant power over the samples. Results correlated storage and packaging effects with macadamia freshness.