Thermomechanical assessment of fruit and vegetable freezing: A thermodynamic approach combining crystallization kinetics and moderate pressure-assisted technology

Abstract

The preservation of perishable produce represents a critical challenge in food engineering. This study assesses the thermomechanical effects of moderate pressure (1–5 atm) on freezing kinetics and structural quality in water-rich plant matrices. A coupled framework was developed based on Fourier heat transfer, Clausius–Clapeyron thermodynamics, and Volmer nucleation theory. Numerical simulations were conducted for a cubic strawberry sample (2×2×2 cm) at −25°C under 1–5 atm, with comparative analyses extended to tomato, apple, carrot, and potato. Quality parameters, freezing time, velocity, convective heat transfer coefficient, ice crystal size, volumetric expansion, drip loss, textural quality, and cellular integrity were computed using established empirical correlations. Increasing pressure from 1 atm to 5 atm reduced freezing time by 25.6% (82 to 61 min), increased freezing velocity linearly (Vf = 0.13P + 1.32, R² = 0.984), and enhanced the convective heat transfer coefficient by 35.7% (28 to 38 W/m²·K). Ice crystal size decreased by 44.6% (92 to 51 μm), while volumetric expansion and drip loss fell by 55.3% and 47.8%, respectively. Textural quality and cellular integrity exhibited bell-shaped curves with optima at 3–4 atm (85% and 92%), beyond which compression induced plastic deformation of cell walls. Multicriteria radar analysis identified 3 atm as the optimal compromise. Moderate pressure-assisted freezing (MPAF) offers a technically feasible and economically viable alternative to high-pressure hydrostatic systems, with significant implications for the frozen food industry in Mediterranean and North African contexts. The 3–4 atm range is achievable with standard industrial compressors, enabling scalable implementation in emerging economies.