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

Abstract

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.

Applications of ultrasonication on food enzyme inactivation- recent review report (2017–2022)

“… 350 MPa; 40 °C; length of exposure to pressure: 5–20 min PPO residual activities reduced to 10.91% for 5 min treatment, which further decreased to 0.12% after 10 min. [118] 3. Apple juice High pressure homogenisation PPO ProbeUS; 24 kHz; 100 µm amplitude; 7–45 min, Temperature – controlled (42 °C) and uncontrolled.…”

Enzymatic browning in apple products and its inhibition treatments: A comprehensive review

“…It provides vibrational energy which causes formation and collapse of bubbles and produces temporary spots during bubble implosion process, which then leads to cavitation. These conditions induce the enzymes’ structural change in the secondary and tertiary structures due to the interruption of hydrogen bond, van der Waals, hydrophobic interaction, electrostatic force in protein/enzyme, thus inhibiting the browning of fruits (Jiang et al., 2020; J. Zhang et al., 2022). Additionally, ultrasound can also inactivate the microbial activity in the fresh‐cut fruits and vegetables by two mechanisms: (a) the cavitation effect that breaks the cell walls, membrane structures, DNA of microbes, and (b) the free radical formation, such as hydroxyl radicals, from which hydrogen peroxide (antibacterial agent) can be formed through some reactions, and hydroxyl radicals can also react with the DNA of microbes (Nicolau‐Lapeña et al., 2019).…”

“…Recently, a study investigated the effect of ultrasound treatment (100–400 W, 5–30 min) on enzymatic browning of apple juice (J. Zhang et al., 2022). It was found that ultrasound at 100 W was too weak to change or destroy the enzymes, and in contrast, it only promoted the interaction between enzymes and phenolics, resulting in higher BI.…”

“…Therefore, dipping treatment with this solution, combined with MAP of 5% O 2 , 5% CO 2 , and 90% N 2 was observed to be the recommendation to inhibit browning (high WI, low Δ E , BI, PPO and POD activities) during 42 days of storage (5°C) (Kumar & Sethi, 2021). Furthermore, the browning inhibition could be improved when apple juice was treated with ultrasound (300 W) in combination with 0.006 g/mL β‐cyclodextrin treatment (J. Zhang et al., 2022). This synergistic impact resulted in up to 39% reduction in BI and 18% reduction in PPO activity, which might be due to increased solubility of β‐cyclodextrin by ultrasound.…”

“…It provides vibrational energy which causes formation and collapse of bubbles and produces temporary spots during bubble implosion process, which then leads to cavitation. These conditions induce the enzymes' structural change in the secondary and tertiary structures due to the interruption of hydrogen bond, van der Waals, hydrophobic interaction, electrostatic force in protein/enzyme, thus inhibiting the browning of fruits (Jiang et al, 2020;J. Zhang et al, 2022).…”