Synergistic effect of high‐intensity ultrasound and β‐cyclodextrin treatments on browning control in apple juice

Summary This work evaluated the synergistic effects of combined high‐intensity ultrasound (HIU) with β‐cyclodextrin (β‐CD) treatments on inhibiting browning of apple juice and explored the mechanism through simulation system. The combined treatment of 300 W HIU with 0.006 g mL −1 β‐CD had a synergistic impact on maintaining juice colour, resulting in a 39.06% reduction in browning degree, only a 36.64% decrease in total phenolic content, and a 17.82% reduction in PPO activity. The inhibition of enzymatic browning in simulated system revealed that HIU suppressed the enzyme (Polyphenol oxidase, PPO) and β‐CD inhibited enzyme (PPO) and embedded substrate (polyphenol). The results of spectroscopic analysis showed that the particle‐size distribution of PPO narrowed, the content of α‐helix in the secondary structure increased, the fluorescence intensity increased, and the maximum wavelength was red‐shifted after HIU and β‐CD treatment. Changes in structure could further result in PPO activity loss. Hence, the combined treatment could synthetically alleviate the browning of apple juice.