Efeito da aplicação de tecnologias não térmicas sobre a composição, características físico-químicas e atividade enzimática da água de coco

Abstract

In this study, the effect of ozone, plasma and ultrasound technologies on coconut water quality was evaluated. For ozone processing, the samples were subjected to different ozone loads and temperatures. For processing by atmospheric cold plasma, the samples were exposed under different frequencies and voltages. For continuous ultrasound processing, the samples were initially tested under 3 different powers, in a single pass through the system (50, 75 and 100%). Subsequently, an experimental design was developed varying the power and the number of cycles (multiple passes through the system). The pH, soluble solids, titratable acidity, color, content of phenolic compounds and enzymatic activity of coconut water were determined before and after treatments. The main compounds were also determined by Nuclear Magnetic Resonance (NMR) spectroscopy. None of the processes changed the pH values, total soluble solids, titratable acidity and color. The chemometric analysis of the NMR data set showed no relevant changes in the contents of sucrose, α-glucose, β-glucose, fructose, malic acid, alanine and valine after application of ozone and atmospheric cold plasma All ozone treatments promoted inactivation of POD activity and did not affect the content of phenolic compounds. After atmospheric cold plasma, the lowest residual POD activity was observed when the highest frequency was applied and small changes in the content of phenolic compounds were observed. None of the Continuous Ultrasound treatments were efficient for enzymatic inactivation and it was possible to observe a small increase in peroxidase activity after processing. In view of these results, ozone stood out as the most suitable technology for the processing of coconut water.