A review on effect of DC voltage on crystallization process in food systems

- Phase change under static electric field permits to enhance the nucleation rate.
- Phase change under static electric field permits to reduce supercooling.
- Phase change assisted by oscillating electromagnetic waves permits to enhance the nucleation rate.
- Application of current flowing in matrices undergoing phase change may affect crystallization.

Crystallization of water and food systems may be affected by electric and magnetic fields. In this review paper, the crystallization of water and food systems assisted by DC voltage (DC-V) is compiled based on existing literature. Two ways of applying DC-V during electrocrystallization can be identified, namely charge flow (CF) conditions with electrical charges flowing through the matrix and static electric field (SEF) conditions. Both processes have shown to interact with nucleation mechanism by reducing supercooling and favouring a higher nucleation rate. The theoretical calculations show that the application of SEF can modify the free energy of formation of ice nuclei in the water phase. Moreover, SEF application can also enhance heat and mass transfer during crystallization process. Various molecular simulations and experimental studies have shown that SEF aligns the water molecules in its direction by the phenomenon of dielectric polarization, and thus, reduces the degree of supercooling (∆T). The freezing process under SEF produces smaller ice crystals in the food products, resulting in less freeze damage; it is thus expected to minimize cell disruption, to reduce the drip loss, to lessen the protein denaturation, and finally to preserve the texture of the fresh food after thawing. Furthermore, freezing under SEF may help to use less energy intensive freezing conditions (higher set point temperature, low air velocity). As a conclusion, the use of DC-V in the case of crystallization of food systems (especially freezing) offers a new perspective to the food industry.