Avidin traps biotin diffusing out of chicken egg yolk

Area of Science:

• Poultry Science
• Biochemistry
• Food Science

Background:

• Freshly laid chicken eggs exhibit unequal distribution of biotin and biotin-binding proteins (BBP) between yolk and albumen.
• This initial distribution suggests potential for biotin redistribution affecting egg quality, availability, and hatchability over time.

Purpose of the Study:

• To investigate the time-dependent redistribution of biotin within chicken eggs during storage.
• To understand the mechanisms and implications of biotin transfer from yolk to albumen.

Main Methods:

• Avidin-bound biotin was quantified in albumen layers (near shell and yolk) of eggs stored up to 23 days.
• Biotin bound to biotin-binding proteins (BBP-I and BBP-II) was measured in yolk (center and periphery).

Main Results:

• Significant biotin accumulation in albumen adjacent to the yolk was observed after 11 days of storage.
• Biotin transfer from yolk to albumen is facilitated by a modified vitelline membrane, allowing biotin diffusion but not BBP-I or BBP-II.

Conclusions:

• The study demonstrates a dynamic biotin redistribution in stored chicken eggs.
• Avidin's role may extend beyond antimicrobial functions to include biotin utilization by the developing chick embryo.