Exploring the Impact of Moderate Electric Field Treatment on Grape Juice: Physicochemical Characteristics and Microbial Reduction

Grape juice, a non-alcoholic and non-fermented beverage, is known for its health benefits primarily due to its diverse phenolic compounds. Effective preservation methods are crucial for preventing spoilage by microorganisms and enzymes, ensuring safety, and extending shelf life. A nonthermal technology called Moderate electric field (MEF) treatment presents a promising approach for preserving liquid food quality and safety with slight effects on its functional and sensory attributes. This study investigated the MEF effect on the physicochemical attributes and microbial reduction of grape juice. The MEF reactor, operating at a frequency of 50 Hz, treated raw grape juice at different voltages (125, 150, and 175 V) and times (5, 10, and 15 min) combinations. The results indicated that MEF treatments significantly influenced temperature, pH, total soluble solids (TSS), turbidity, conductivity, color, and microbial reduction in grape juice. Higher voltages and longer treatment times generally resulted in higher temperatures and more pronounced changes in the juice's properties. Specifically, treatment T₁₉ (175 V for 15 min) showed the most significant effects, including increased TSS, turbidity, conductivity, and total color difference, while substantially reducing the microbial count. A maximum log reduction of 3.43 was achieved at 175 V for 15 min. These findings suggest that MEF treatment can effectively enhance grape juice quality and safety while preserving its nutritional and sensory attributes, particularly under specific conditions.