Comparative Assessment of Thermal and Non-Thermal Processing of Green Leafy Vegetables: A Comprehensive Review

Green leafy vegetables (GLVs) are important sources of essential nutrients and bioactive compounds and play a significant role in preventing malnutrition and improving food security, particularly in developing countries. However, their high perishability limits their availability and utilization throughout the year. Appropriate processing technologies are therefore essential to extend shelf life while preserving nutritional quality. This review provides a comprehensive assessment of how thermal and non-thermal processing methods influence the nutritional, functional, and sensory properties of green leafy vegetables. Thermal processing techniques such as blanching, drying, microwave heating, pasteurization, and ohmic heating are widely used for enzyme inactivation and microbial control, but they may lead to the degradation of heat-sensitive nutrients under certain conditions. In contrast, emerging non-thermal technologies including ultrasound, pulsed electric fields, cold plasma, irradiation, and supercritical fluid extraction have shown potential to improve the retention of bioactive compounds and sensory attributes while maintaining product safety. The review also highlights current research gaps, emerging trends, and future prospects for the effective utilization and value addition of underutilized green leafy vegetables.