Kinetic modelling of ascorbic and dehydroascorbic acids concentrations in a model solution at different temperatures...

Area of Science:

• Food Chemistry
• Chemical Kinetics
• Nutritional Science

Background:

• Vitamin C, comprising ascorbic acid (AA) and dehydroascorbic acid (DHA), is vital but unstable.
• Understanding its degradation kinetics is essential for preserving nutritional value in food products.

Purpose of the Study:

• To determine the degradation kinetics of vitamin C (AA and DHA) under varying temperatures and oxygen concentrations.
• To develop a kinetic model simulating vitamin C degradation in an apple puree-like matrix.

Main Methods:

• Controlled experiments were conducted in a specific reactor using malate buffer (pH 3.8) at temperatures from 50-90°C and oxygen concentrations of 10-30%.
• Vitamin C levels were quantified spectrophotometrically at 243 nm at regular intervals.
• A kinetic model involving two consecutive first-order reactions was developed and validated against experimental data.

Main Results:

• Ascorbic acid (AA) degradation rate increased with temperature and oxygen concentration.
• Dehydroascorbic acid (DHA) acted as an intermediate, forming and then degrading.
• The kinetic model accurately simulated experimental data, with both reaction steps following Arrhenius' law.

Conclusions:

• Temperature and oxygen concentration are key factors influencing vitamin C degradation.
• A robust kinetic model can predict vitamin C stability under various processing conditions.
• Findings provide valuable insights for optimizing food processing to minimize vitamin C loss.