Effects of roasting and frying pretreatments on the nutritional, physicochemical, and sensory properties of hazelnut milk with direct grinding of raw kernels as a comparison.

This study optimized the lye-peeling and pulping processes for hazelnut milk (HM) production and systematically compared three pretreatment methods: non-thermal raw grinding (PHM), thermal-stir-frying (FHM), and thermal-roasting (RHM). All HM samples exhibited high unsaturated fatty acids (> 93.00%). Thermal treatments significantly reduced pH and increased phase separation, with FHM group showing the poorest physical stability. However, FHM group demonstrated superior nutritional and functional properties, including the highest total polyphenols (108.43 ± 2.36 μg GAE/mL) and flavonoids (39.80 ± 0.80 μg CE/mL), along with the strongest radical scavenging activities against DPPH and hydroxyl radicals scavenging activities. Furthermore, GC-MS, e-nose, and e-tongue analysis confirmed that FHM group was enriched in volatile ketones, aldehydes, and furans, resulting in the highest sensory evaluation score. These findings highlight the critical trade-off between physical stability and sensory-nutritional quality in plant-based nut milks, providing guidance for precision processing.