Ascorbic acid and ascorbic acid 6-palmitate induced oxidation in egg yolk dispersions

Area of Science:

• Food chemistry
• Oxidation mechanisms
• Antioxidant activity evaluation

Background:

• Egg yolk powder is susceptible to oxidation, impacting its quality and shelf-life.
• Ascorbic acid and its esters are commonly considered antioxidants, but their behavior in complex food matrices requires investigation.

Purpose of the Study:

• To investigate the effect of ascorbic acid and ascorbic acid 6-palmitate on the oxidation of egg yolk powder dispersions.
• To determine the prooxidative or antioxidative potential of these compounds in this specific system.

Main Methods:

• Preparation of aqueous egg yolk powder dispersions.
• Addition of varying concentrations of ascorbic acid and ascorbic acid 6-palmitate.
• Monitoring of oxidation levels and free iron (Fe(II)) content.

Main Results:

• Both ascorbic acid and ascorbic acid 6-palmitate promoted lipid oxidation in egg yolk dispersions.
• Ascorbic acid 6-palmitate exhibited a stronger prooxidative effect compared to ascorbic acid.
• Addition of these compounds led to an increased amount of free Fe(II), suggesting iron release.

Conclusions:

• Ascorbic acid and ascorbic acid 6-palmitate act as prooxidants in egg yolk powder dispersions, contrary to their expected antioxidant roles.
• The prooxidant activity is likely mediated by the release of free iron (Fe(II)) through interaction with the phosvitin-Fe(III) complex.
• These findings highlight the importance of considering the matrix effect when evaluating antioxidant efficacy.