Impact of Pulsed Electric Field, High-Pressure Processing, Combined, and Thermal Treatments on the Quality of Tender Coconut Water During Refrigerated Preservation

Abstract

Tender coconut water (TCW) is a nutrient-rich natural beverage with several health benefits and is highly prone to spoilage once extracted from the nut due to microbial contamination and its nutrient-rich composition. Conventional heat thermal preservation methods, like pasteurization, often degrade sensitive nutrients and affect sensory quality. In contrast, non-thermal methods like high-pressure processing (HPP) and pulsed electric field (PEF) have shown promise for better quality retention. In this study, the effects of PEF (16 kV/cm for 0.84 s; 12,000 pulses × 70 µs pulse width), HPP (475 MPa for 6 min), combined treatment (PEF + HPP), and thermal processing (90 °C for 5 min) on the overall quality of TCW during refrigerated storage were evaluated. The impact of these treatments on mineral content and volatile composition was also assessed. Results revealed that PEF and HPP enhanced total phenolic content and antioxidant activity significantly (p < 0.05) and by at least 10%, whereas combined and conventional heat treatments caused significant reductions (p < 0.05). No significant differences were observed in pH, total soluble solids, viscosity, and sugar content immediately after treatment. Complete inactivation of polyphenol oxidase was achieved by PEF, combined, and conventional heat treatments, while peroxidase remained more resistant. Microbial counts remained within acceptable limits across treatments. During storage, a gradual decline in pH, viscosity, protein, and vitamin C, along with increased microbial growth, enzyme activity, and reducing sugars, was noted. Based on sensory evaluation, physicochemical stability, nutritional retention, and cost considerations, PEF emerged as the most effective method for preserving TCW quality for up to 25 days under refrigeration.

Graphical Abstract