Destructive and non-destructive techniques used for quality evaluation of nuts: A review

Moisture content (MC), oil content (OC), fatty acid composition and rancidity are considered as major determinants of quality of nuts. These parameters are destructively quantified from a batch of representative samples used to estimate quality of nuts of an entire orchard. Although destructive techniques are helpful, they involve extensive sample preparation and solvent extractions, are slow, expensive and obtained results specifically reflect the properties of the evaluated produce. Recently, non-invasive analytical methods and instruments for evaluating quality of various produce have become popular with researchers putting more effort in developing them. Non-destructive methods are an alternative to traditional methods for inspection of internal quality parameters because they are fast, simple and cost-effective. In this review, invasive and non-invasive analytical methods and instruments for evaluating MC, OC, fatty acid composition and rancidity in different nuts are discussed. This paper also reviews the implementation of visible to near infrared spectroscopy, nuclear magnetic resonance and X-ray computed tomography on nuts for evaluation of quality attributes. Technical challenges and future possibilities for commercial use of these non-invasive methods for quality evaluation of nuts are presented.