Use of an electrochemically etched platinum microelectrode for ascorbic acid mapping in oranges

Area of Science:

• Electrochemistry
• Food Science
• Analytical Chemistry

Background:

• Ascorbic acid (vitamin C) is a vital nutrient with significant roles in human health.
• Accurate quantification of ascorbic acid in fruits and vegetables is crucial for nutritional analysis and quality control.
• Existing methods for ascorbic acid determination can be time-consuming or lack spatial resolution.

Purpose of the Study:

• To develop and validate a positionable platinum microelectrode for selective ascorbic acid monitoring.
• To investigate the spatial distribution of ascorbic acid within oranges.
• To explore the relationship between fruit ripeness and ascorbic acid concentration.

Main Methods:

• Fabrication of a platinum microelectrode using electrochemical etching.
• Amperometric sensing utilizing ascorbate oxidase for selective ascorbic acid detection.
• In-situ electrochemical measurements for spatial mapping and ripeness correlation.
• Comparison with traditional iodimetry for validation.

Main Results:

• The microelectrode demonstrated selective and accurate ascorbic acid measurement, with a standard deviation of 3%.
• Spatial distribution analysis revealed higher ascorbic acid concentrations near the peel in perpendicular cuts and increasing concentration with distance from the stem in parallel cuts.
• A positive correlation was observed between fruit maturity and ascorbic acid content.

Conclusions:

• The developed platinum microelectrode is a suitable tool for selective and spatially resolved ascorbic acid determination in fruits and vegetables.
• Electrochemical measurements provide valuable insights into the distribution and changes in ascorbic acid content during fruit ripening.
• This method offers a promising alternative for quality assessment and nutritional profiling of produce.