Microbial Inactivation and Shelf-Life Extension of Vegetables Using Hybrid UV-A/UV-C Assisted Dehydration

Abstract

Post-harvest losses of perishable vegetables remain a major food security challenge in sub-Saharan Africa, where inadequate preservation technologies accelerate microbial spoilage and quality deterioration. This study evaluated a fabricated hybrid UV-C/UV-A–assisted dehydrator for microbial inactivation and shelf-life extension of onion (Allium cepa), okra (Abelmoschus esculentus), and tomato (Solanum lycopersicum). Vegetables were subjected to UV-C (570 mJ cm⁻²) and UV-A (8100 mJ cm⁻²) during dehydration and stored under ambient conditions for 48 days. Total viable count (TVC), moisture reabsorption, and microbial growth kinetics were assessed and statistically analyzed using log₁₀-transformed ANOVA (p < 0.05). UV-treated samples exhibited an immediate microbial reduction of approximately one log cycle and maintained significantly lower microbial loads throughout storage compared with controls. By Day 48, UV-treated vegetables remained within acceptable microbiological limits, while control samples approached or exceeded safety thresholds. Additionally, UV-treated samples showed up to 7% lower moisture reabsorption, contributing to suppressed microbial proliferation. The findings demonstrate that hybrid UV-C/UV-A dehydration provides a synergistic non-thermal preservation mechanism combining microbial inactivation and moisture control. This approach offers a scalable, energy-efficient solution for reducing post-harvest vegetable losses under tropical storage conditions.