An electrochemical alternative for evaluating the antioxidant capacity in walnut kernel extracts

Area of Science:

• Analytical Chemistry
• Food Science
• Electrochemistry

Background:

• Traditional methods for assessing antioxidant activity (AA) in walnut kernel extracts can be time-consuming and costly.
• Developing rapid, precise, and inexpensive alternatives is crucial for quality control and research.

Purpose of the Study:

• To propose and validate a novel electrochemical index (EI) approach as a fast, precise, and inexpensive alternative for evaluating antioxidant activity in walnut kernel extracts.
• To compare the EI approach with the traditional ABTS spectrophotometric assay.

Main Methods:

• Ultrasound-assisted extraction (UAE) was employed for efficient defatting and subsequent extraction of polyphenolic compounds using an ethanolic medium.
• Antioxidant activity was determined using the ABTS spectrophotometric method (% inhibition) and the electrochemical index (EI) approach via differential pulse voltammetry (DPV) at a Sonogel-Carbon electrode.
• The EI approach was validated using six polyphenol standards and eleven consumer walnut kernel samples at pH 2.

Main Results:

• A high and significant correlation (R² = 0.927) was observed between the ABTS assay results and the EI approach for walnut kernel extracts.
• All tested polyphenols exhibited oxidation potentials between 0.476 and 0.778 V.
• The electrochemical method demonstrated high precision and speed in evaluating antioxidant activity.

Conclusions:

• The electrochemical index (EI) approach provides a reliable, fast, and cost-effective method for assessing antioxidant activity in walnut kernel extracts.
• This electrochemical method shows excellent agreement with the established ABTS assay, making it a viable alternative for routine analysis.
• The findings support the use of electrochemical techniques for rapid quality assessment of food products rich in antioxidants.