Validation of a high-throughput method for the accurate quantification of secondary products of lipid oxidation in high-quality hazelnuts (Corylus avellana L.): A robust tool for quality assessment

European hazelnuts (Corylus avellana L.) are a key ingredient for the confectionery industry with a distinctive flavor profile and high nutritional quality. However, the high-fat content makes raw kernels prone to autoxidation that takes place during storage. Fatty acids hydroperoxides (i.e., primary products of oxidation) readily decompose by forming volatile secondary products with low odor thresholds and negative aroma notes. This study presents method performance parameters of an accurate quantitative methodology, based on multiple headspace solid-phase microextraction (MHS-SPME) coupled to conventional and fast gas chromatography–mass spectrometry ((Fast)GC–MS), targeted to oleic and linoleic acids autoxidation products (i.e., hexanal, heptanal, octanal, and nonanal). Results refer to good repeatability (max RSDr 12%) and intermediate precision (max RSDR 19.6%); linearity over four orders of magnitude (R2 ≥ 0.995 and calibration error ≤ 20%); good accuracy (error bias ≤20%); limit of detection and quantification compatible with real-world samples oxidative levels. Experimental results from method application on 358 industrial samples, confirm the method's effectiveness and its information capacity; moreover, for medium-to-high oxidized samples, the quantification of a larger set of products instead of a single marker (i.e., hexanal), provides a more accurate picture on the actual quality/rancidity level.