Determination of conformational changes of polyphenol oxidase and peroxidase in peach juice during mild heat treatment using FTIR spectroscopy coupled with chemometrics

다국어 초록 (Multilingual Abstract)

Effect of thermal treatment on peach PPO and POD by using FTIR was examined. FSD and curve‐fitting were applied to determine secondary structural components. Native and denaturated forms of enzymes was discriminated with PCA. Models were constructed to correlate activity and structure with IR data with PLS.
The effect of thermal treatment on activity and structural changes of polyphenol oxidase (PPO) and peroxidase (POD) in peach juice was investigated. The D70 values for PPO and POD were 10.38 and 13.68 min, respectively. The z values for PPO and POD were found to be 3.35 and 23.15 °C, respectively. Fourier transform infrared (FTIR) spectroscopy was used to determine the conformational changes. With the increase in temperature, α‐helix and β‐sheet were decreased, and β‐turn and aggregated β‐sheet structure were increased for PPO, random coil and β‐sheet decreased, while aggregated β‐sheet structure increased for POD. In contrast, an increase in α‐helix structure of POD was observed which was thought to be effective in POD regeneration. Furthermore, native and denatured forms of enzymes were discriminated by using principle component analysis (PCA), and models that correlated activity and secondary structural components with infrared spectra were constructed by using partial least square (PLS).