Non-Thermal Physical Technologies for Leafy Vegetable Processing: A Review of Cleaning, Microbial Inactivation, and Quality Preservation

Leafy vegetables are an indispensable component of the global diet, yet their complex surface microstructures, including stomata, grooves, and waxy cuticles, readily entrap or retain microorganisms and pesticide residues, posing significant food safety risks. This review integrates direct evidence for ultrasound (US), cold plasma (CP), pulsed electric field (PEF), ultraviolet-C (UV-C), and high-pressure processing (HPP) across three practical product forms: intact or fresh-cut leaves, packaged leafy products, and leaf-derived juices or purees. The analysis links each technology's physical mechanism to the processing objective that it can most directly address. US and CP provide the broadest direct evidence for surface cleaning and microbial control on leaves, while UV-C is useful when exposed surfaces receive a verified dose. PEF becomes more useful after conversion to a conductive juice or as a tissue-permeabilization step, and HPP has evidence in packaged vegetables, kale and spinach matrices, and mixed juice systems, although the quality response of crisp fresh leaves differs from that of homogenized products. Tables 1 and 2 retain the original experimental units and conditions, and Table 3 synthesizes the resulting product-form and process-function relationships. The review therefore provides a basis for matching technology to leaf geometry, product form, and quality objective rather than ranking heterogeneous laboratory values.