Interaction between casein and vitamin A during food processing

Area of Science:

• Biochemistry
• Nutrition Science
• Food Chemistry

Background:

• Vitamin A (retinol) is essential for vision and cellular function.
• Casein, a major milk protein, is known to interact with various molecules.
• Understanding these interactions is crucial for optimizing nutrient delivery and stability.

Purpose of the Study:

• To investigate the relationship between casein micelle and vitamin A (retinol).
• To elucidate the binding mechanisms of retinol to acid casein in vitro.
• To assess the impact of casein on retinol bioavailability and stability in vivo.

Main Methods:

• In vitro studies using acid casein and its fractions to analyze retinol binding.
• Exposure to physico-chemical parameters (alkalinity, heat) to study binding facilitation.
• In vivo studies measuring vitamin A liver content to assess retinol efficiency.
• Saponification to identify strong retinol-casein binding.

Main Results:

• Retinol binds to acid casein via hydrophobic interactions, particularly with Trp and Phe residues.
• Alkalinity and heat treatments enhance retinol binding through conformational changes in casein.
• A portion of retinol is strongly bound to casein, requiring saponification for release.
• Casein stabilizes retinol against degradation during storage and heat treatments.
• In vivo, acid casein increases retinol and retinal efficiency, particularly under specific dietary conditions.

Conclusions:

• Casein plays a significant role in stabilizing vitamin A (retinol) through distinct binding mechanisms.
• The in vitro binding properties of casein for retinol suggest potential for improved nutrient delivery.
• Further research is needed to reconcile in vitro binding data with in vivo observations on retinol efficiency.