Application of hydrogen-assisted freezing technology: Promises and challenges

Background: The formation and growth of ice crystals and cold stress effect lead to irreversible oxidative damage that affects the quality of frozen products during the freezing process. Although it has been established that certain gases such as carbon dioxide (CO2) and xenon (Xe) may help mitigate the damage caused by ice crystals, the adverse effects of cold stress, particularly oxidative damage, have not been fully addressed. Scope and approach: The review commences with an explanation of the current research progress in gas-assisted freezing technology utilizing CO2 and Xe. And its potential mechanism affects the nucleation and growth of ice crystals. In addition, the potential applications of hydrogen-assisted freezing have been discussed on account of its exceptional physicochemical properties and recent findings across various fields. The review identifies the primary limitations associated with hydrogen-assisted food-freezing and ultimately underscores the potential future advancements of hydrogen-assisted freezing technology. Key findings and conclusions: The hydrogen has the potential to enhance the quality of frozen product by expediting the freezing process. It has unique physical properties, faster diffusivity higher thermal conductivity, and better heat dissipation capacity, which enables the ability to mitigate oxidative damage and accelerate freezing rate. Hydrogen bubbles and their collapse suppress the insufficient nucleation and oversize growth of ice crystals. Future research for hydrogen-assisted freezing should address the issues concerning its safety in storage related to hydrogen in order to deepen its application scenarios. It will provide theoretical and technical support for using hydrogen in biological science, particularly assisted-food-freezing.