Research note: Study on liquid-liquid phase separation of thick and thin egg white

Area of Science:

• Food Science
• Biochemistry
• Materials Science

Background:

• Fresh egg white exhibits natural liquid-liquid phase separation between "gel-like" thick egg white (TKEW) and "solution-like" thin egg white (TNEW).
• Understanding the stability of this phase separation is crucial for egg white processing and utilization.

Purpose of the Study:

• To systematically analyze the factors affecting the liquid-liquid phase separation stability of TKEW and TNEW.
• To identify the primary mechanism driving phase separation and the conditions that influence it.

Main Methods:

• Investigated the impact of storage temperature and time on egg white phase separation.
• Evaluated the effects of ultrasonic treatment, mechanical stirring, and chemical ions (specifically phosphate-buffered saline) on phase stability.
• Monitored changes in TKEW structure and viscosity.

Main Results:

• The collapse of the TKEW gel structure is identified as the critical factor causing liquid-liquid phase separation.
• Room temperature storage accelerates TKEW gel structure collapse and viscosity reduction, leading to phase separation instability.
• Ultrasonic treatment, stirring, and acidic phosphate-buffered saline (20 mmol/L) promote TKEW reduction and interface disappearance.
• Salt at physiological concentrations enhances TKEW stability.

Conclusions:

• The stability of the TKEW and TNEW liquid-liquid phase is primarily governed by the integrity of the TKEW gel structure.
• Environmental factors like temperature, storage duration, mechanical/ultrasonic forces, and specific chemical conditions significantly influence phase separation.
• The findings provide a foundational understanding for optimizing egg white storage and exploring diverse applications.