Making egg white foam may not be difficult, but making that foam survive freezing and thawing is decidedly not a piece of cake.
Huazhong Agricultural University researchers have found that a combination of sucrose and supercritical carbon dioxide could help egg white proteins rise to the challenge, improving both their foaming ability and stability.
The study was published in Food Science of Animal Products on June 30.
Rich in protein and low in calories, egg white is popular among dieters. For bakers, it is no less attractive thanks to its exceptional foaming properties. This humble yet remarkable ingredient can make the difference between a cake that rises beautifully and one that falls flat.
Once obtained only fresh from the hen, eggs now come in multiple other forms, be they liquid, dried or frozen, for the sake of easier storage or transportation. That convenience, however, doesn't come without a cost.
"Prolonged storage and repeated freeze-thaw cycles can cause irreversible structural changes that impair the foaming properties of egg white," said Zhaoxia Cai, professor at Huazhong Agricultural University and lead author of the study.
Looking for a solution, the team turned to sucrose, commonly known as table sugar, together with supercritical carbon dioxide (SCCD), a high-pressure state of carbon dioxide with both gaseous and liquid properties.
"We found that the combined treatment can substantially improve both egg white's foaming performance and its resistance to repeated freeze-thaw cycles," Cai said.
The treatment increased the foaming capacity to a maximum of 139.5% — 4.6 times that of untreated protein — when treated at 9 megapascals for 60 minutes with 10 grams of sucrose per 100 milliliters. Whilst SCCD treatment alone compromised foaming stability, or how well foam retains its volume over time, adding sucrose helped both preserve the foam's stability and maintain the improved foaming capacity.
The researchers proposed that sucrose works in several ways. It increases the viscosity of the liquid surrounding the proteins, which can slow the movement and collapse of foam bubbles. At the same time, sucrose interacts with the proteins through hydrogen bonding and hydrophobic interactions, encouraging them to associate into larger aggregates. These changes allow proteins to form stronger structures at the boundary between air and water — the critical interface that surrounds and supports each bubble in a foam.
A variety of further analyses, ranging from Fourier transform infrared spectroscopy to scanning electronic microscopy, showed that the treatment helped the SCCD-sucrose-treated proteins adopt a more organized structure and form a stronger network than untreated proteins.
These changes appear to counteract the structural loosening associated with SCCD treatment and promote the formation of a stronger protein layer around air bubbles.
The improved freeze-thaw stability could be particularly relevant for liquid egg white products that are frozen for storage and later thawed before use. By helping egg white proteins retain their functional properties through repeated freeze-thaw cycles, the treatment could significantly improve the performance of frozen-stored liquid egg white.
"Our findings provide a promising physical modification strategy for enhancing the functional properties of egg white protein, potentially supporting its use in food products that require strong and stable foaming properties," Cai said.
Funding
- National Key R&D Program of China (2025YFE0117800),
- Key R&D Program of Zaozhuang-National Agenda for Sustainable Development Innovation Demonstration Zone (2025SFQZX15),
- Shandong Provincial Central Guided Local Science and Technology Development Project (YDZX2024056).
DOI Link:
https://doi.org/10.26599/FSAP.2026.9240170
