Nitrogen-protected microwave-assisted extraction of ascorbic acid from fruit and vegetables

Area of Science:

• Analytical Chemistry
• Food Science
• Green Chemistry

Background:

• Ascorbic acid (AA) is an essential nutrient prone to oxidation.
• Conventional extraction methods can lead to significant loss of AA due to oxidation.
• Developing efficient and protective extraction techniques is crucial for accurate AA determination.

Purpose of the Study:

• To develop and validate a novel nitrogen-protected microwave-assisted extraction (NPMAE) method.
• To optimize NPMAE conditions for ascorbic acid extraction.
• To evaluate the efficacy of NPMAE in preventing AA oxidation and improving extraction yield.

Main Methods:

• Development of nitrogen-protected microwave-assisted extraction (NPMAE).
• Optimization of extraction parameters: 0.25% metaphosphoric acid, 1:10 g/mL solid/liquid ratio, 400 W microwave power, 10 min irradiation.
• High-Performance Liquid Chromatography (HPLC) for ascorbic acid determination.
• Comparative analysis with conventional microwave-assisted extraction (MAE) and solvent extraction.

Main Results:

• NPMAE significantly reduced or prevented ascorbic acid oxidation during extraction.
• Optimized NPMAE conditions yielded higher extraction efficiency for AA.
• The method demonstrated effectiveness across various matrices including guava, yellow pepper, green pepper, and cayenne pepper.
• Achieved higher extraction yields compared to conventional MAE and solvent extraction methods.

Conclusions:

• Nitrogen-protected microwave-assisted extraction (NPMAE) is a highly effective method for extracting oxidizable compounds like ascorbic acid.
• NPMAE offers a superior alternative to conventional methods, minimizing analyte degradation.
• The developed NPMAE technique shows significant potential for analyzing labile compounds in diverse food matrices.