Mechanical Thresholds and Texture Integrity in Stone Fruits: A Hertzian Contact Approach

Mechanical characterization of fruits is essential not only for postharvest system design but also for understanding texture integrity, which directly influences consumer perception and acceptability. In this study, four stone fruits-aonla, peach, plum, and sapota-were evaluated using quasi-static compression tests. Force-deformation curves were analyzed with Hertzian contact theory to estimate effective and actual elastic moduli, providing quantitative indicators of firmness and tissue resilience. Aonla exhibited the highest firmness (Elastic Limit 69.38 N, Rupture 250 N, E 4.62 MPa), while plum and sapota showed lower thresholds, reflecting softer, more deformable textures. Mechanical strength correlated strongly with pulp-to-stone ratio and moisture content, parameters that shape consumer-perceived juiciness and resistance to bruising. Hertzian analysis proved a robust predictor of fruit texture and mechanical resistance, offering quantitative descriptors that bridge engineering mechanics with sensory quality. These findings provide actionable insights for fruit-specific handling, storage, and processing systems aimed at preserving desirable textural attributes.