# Determination of pH-dependent antioxidant activity of palm (Borassus flabellifer) polyphenol compounds by photoluminol and DPPH methods: a comparison of redox reaction sensitivity

## TL;DR

This study compares how pH affects antioxidant activity in fermented palm juice using two methods, finding that higher pH increases antioxidant levels.

## Contribution

The study introduces a comparison of DPPH and photoluminol methods for measuring pH-dependent antioxidant activity in palm polyphenols.

## Key findings

- Total phenolics and antioxidant activity increase with pH (3.5 < 4.5 < 5.5).
- Maximum flavonoid concentration was observed at pH 6.5.
- DPPH and photoluminol methods showed strong correlation (R² = 0.94).

## Abstract

Palm juice (Borassus flabellifer) is one of the most common and cheap natural juices. Fermented palm juice contains various phytochemical compounds that exhibit antioxidant activity. In the present study, we examined the effects of pH on the production of phytochemicals and their antioxidant activity during the fermentation process. The concentration of total phenolics and flavonoid compounds of fermented palm juice and their antioxidant activity were investigated at various pH. The results showed that total phenolics concentration and antioxidant activity of palm wine and palm vinegar increase as pH increases: 3.5 < 4.5 < 5.5. Maximum flavonoid concentration was obtained at pH 6.5. Measurements of antioxidant activity by conventional DPPH method and Photochem antioxidant analyzer technique were highly correlated, with a corresponding R
2 value of 0.94.