Riboflavin-sensitized photochemical changes in beta-lactoglobulin in an aqueous buffer solution as affected by...

Area of Science:

• Biochemistry
• Food Science
• Photochemistry

Background:

• Beta-lactoglobulin is a major whey protein susceptible to photodegradation.
• Riboflavin acts as a photosensitizer, accelerating protein damage under light exposure.
• Ascorbic acid is a known antioxidant with potential protective properties.

Purpose of the Study:

• To investigate the inhibitory effects of ascorbic acid on riboflavin-sensitized photodegradation of beta-lactoglobulin.
• To quantify the impact of ascorbic acid on protein insolubility and amino acid degradation.
• To determine the concentration-dependent efficacy of ascorbic acid as a photoprotective agent.

Main Methods:

• Beta-lactoglobulin solutions were exposed to fluorescent light with and without riboflavin and varying concentrations of ascorbic acid.
• High-performance gel permeation liquid chromatography (HPGPLC) was used to assess protein degradation.
• Insoluble protein content and individual amino acid profiles were analyzed.

Main Results:

• Ascorbic acid significantly inhibited beta-lactoglobulin photodegradation, with 0.1% ascorbic acid showing 74.4% inhibition.
• Ascorbic acid treatment reduced the insolubility of beta-lactoglobulin during light exposure.
• Ascorbic acid demonstrated 20.8% inhibition of total amino acid degradation, notably protecting arginine, aspartic acid, and tryptophan.

Conclusions:

• Ascorbic acid is an effective inhibitor of riboflavin-sensitized beta-lactoglobulin photodegradation.
• The photoprotective effect of ascorbic acid is concentration-dependent.
• Ascorbic acid preserves the amino acid integrity of beta-lactoglobulin under light-induced oxidative stress.