Pre-freezing enhances volatile aroma retention and essential oil quality during conventional grinding of black pepper

Conventional pepper grinding generates frictional heat, accelerating volatile loss and reducing aroma quality. Cryogenic grinding can reduce thermal damage, but it is limited by dedicated equipment, continuous liquid-nitrogen consumption, and post-grinding temperature equilibration. This study evaluated pre-freezing before conventional grinding as a practical approach. Black peppercorns were pre-frozen at −10, −20, −30, or −40 °C and ground using a production-scale grinder. Particle properties, moisture, microstructure, volatile profiles, essential oil retention, and electronic-nose responses were analyzed. Pre-freezing increased brittleness, promoted finer particles, and enhanced cell-wall rupture, while reducing grinding-chamber temperature from 58.8 °C to 43.4 °C at −30 °C pre-freezing and 40.3 °C at −40 °C. Pre-freezing improved volatile retention, increasing essential oil content by up to 10.7% and terpenes markedly. Among treatments, −30 °C provided the best balance among flavor retention, oil preservation, grinding performance, and moisture stability, offering a practical strategy for black pepper powder production using conventional equipment.