Changes in enzymatic activity of polyphenol oxidase and its structural modification in apple juice subjected to high pressure carbon dioxide | [International Food & Nutrition Conference" August 18th-20th, 2022, University of Swat, Swat (Book of Abstracts) • 2022]

Author(s):

1. Ayesha Murtaza: Department of Food Science and Technology,UCP, Lahore,Pakistan

2. Aamir Iqbal: College of Agriculture & Life Sciences, Cornell University,Ithaca, New York, the,United States

3. Shinawar Waseem Ali: Institute of Agricultural Sciences, University of the Punjab,Lahore,Pakistan

4. Muhammad Usman: Institute of Agricultural Sciences, University of the Punjab,Lahore,Pakistan

5. Sarah Murtaza: Department of Economics and Business Administration, Central China Normal University,Wuhan,China

Abstract:

This study investigated the effect of different states of CO2 on the activity and structural modification of purifiedpolyphenol oxidase (PPO) from apple juice. Result showed that PPO retained most of its residual activity at gaseous and liquid states even at a high temperature of 40 °C for 5 MPa. CO2 in the critical (31.1 °C for 7.38 MPa) and supercritical states (55 °C for 25 MPa) strongly inhibited the PPO activity up to 64.88% and 3.20%, respectively. Dynamic light scattering analysis showed that the two peaks depolymerized into three peaks at 8.72, 37.8 and 220 nm in the critical state, demonstrating the dissociation and aggregation of small particles. In the super critical state, the peak transferred to 531 nm, indicating the aggregation of large particles. Circular dichroism spectral analysis revealed that the secondary structure deformed because of the loss of a-helix contents in the critical and super critical states of CO2 compared with those of the native structure. Fluorescence intensity dramatically decreased to 251.3 (??max 312) in the critical state, showing unfolding of PPO molecules thereby resulting in quenching and blue shifting of ?max. Polyacrylamide gel electrophoresis analysis indicated that large molecular aggregates did not run into the gel at supercritical state. Hence, High pressure CO2 treatment in critical and super critical states could induce the aggregation, deformation and structural changes in catalytic active center of PPO. These structural modifications might be the causes of PPO inactivation after processing was accomplished.

Page(s): 125-125

DOI: DOI not available

Published: Journal: International Food & Nutrition Conference" August 18th-20th, 2022, University of Swat, Swat (Book of Abstracts), Volume: 1, Issue: 1, Year: 2022

Keywords:

Polyphenol oxidase , enzymatic activity , Apple juice

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