Non-thermal processing of coconut water

In this study, the effect of plasma and ozone processing on the quality of coconut water was evaluated. For ozone processing, the samples were submitted to different ozone loads (0.075, 0.225 and 0.370 mg O3/mL) and temperatures (10, 20 and 30 °C). For atmospheric cold plasma processing (ACP), samples were exposed to plasma generated by dielectric barrier discharge (DBD) under different frequencies (200, 400, 550, 730 Hz) and voltages (15 and 20 kV). The coconut water pH, soluble solids, titratable acidity, color, total phenolic content and enzymatic activity were determined before and after treatments. The main compounds (sugars, amino acids and organic acids) were also determined by NMR spectroscopy and chemometric analysis. Both processes did not change significantly the pH values, total soluble solids, titratable acidity and color. Moreover, not relevant changes were verified based on chemometrics analysis of 1H NMR dataset after processes. All ozone treatments promoted total inactivation of POD activity and did not affect the amount of phenolic compounds, maintaining the nutritional quality. After ACP process, the smallest residual activity of POD was observed when higher frequencies were applied and regarding phenolic compounds, there was reduction of procyanidin dimer type B and chrysoeriol and increase of trans-zeatin riboside, caffeoylshikimic acid and procyanidin dimer type A. Therefore, ozone and atmosphere cold plasma can be alternatives of non-thermal treatment for preservation of coconut water.