A volatile aldehyde-based rancidity score index for robust hazelnut quality monitoring.

Abstract

Reliable monitoring of hazelnut (Corylus avellana L.) oxidation is a critical challenge. Traditional indices have limited specificity and dynamic range, while single markers approaches lack robustness. This study introduces the Rancidity Score Index (RSI), a data-driven metric based on the combined quantification of four aldehydes (hexanal, heptanal, octanal, and nonanal) using Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS). The RSI (0-100 scale value) was developed and validated on 416 industrial samples collected over four crop years (2020-2023) from Turkey and Italy, encompassing multiple cultivars and storage conditions monitored for 24 months. Principal Component Analysis (PCA) showed that the four aldehydes co-varied along a dominant axis explaining ~80% of total variance, while K-means clustering enabled the translation of the continuous RSI into a three-cluster framework. Preliminary agreement between MS- and FID-derived RSI values (r = 0.974, n = 30) supports potential transferability to portable GC platforms for industrial rapid monitoring, pending validation.

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