Ice crystal growth of living onion epidermal cells as affected by freezing rates

Abstract

The entire crystallization process and the effect of freezing rates on the temperature of spontaneous freezing (TSF) of living onion epidermal cells were analysed in this study. The cells, stained with iodine at a concentration of 1%, were frozen at three different freezing rates, i.e. 2, 1.2, and 0.5°C/min, and were thawed at 5°C/min. The higher freezing rate caused a higher TSF. Moreover, this article presents a method for determining whether a cell is inactivated by a plasmolysis experiment. The results of plasmolysis showed that the formation of ice crystals did not cause fatal mechanical damages to the cells, even when the freezing rate was as slow as 0.1°C/min. Finally, this article also demonstrated the grey-scale changes that occurred in the cells, as evidenced by an image processing technique. This further highlighted the ice crystal growth process and showed the ice crystal content at different locations inside the cells.

Mechanism of ultrasound assisted nucleation during freezing and its application in food freezing process

“…UAF can effectively promote the formation of small and evenly distributed ice crystals and improve the microstructure. Zhu et al [102] evaluated the effect of triple-ultrasound assisted freezing on potato quality. Figure 9 show scanning electron microscopy (SEM) images of potato samples with different freezing conditions.…”

Effect of cytoskeleton on ice crystal growth in cells during freezing

“…[19] Kasper thought the ice nucleation temperature was recognized as a key factor in determining both the processing time and recovery of biological activity on rehydration. [20] Duohua Xu [21] studied the crystallization process of onion cells and showed different numbers of ice in different cells. However, due to the limitations of imaging technology, the influence of the internal structure of cells on the growth of ice crystals has not been analyzed.…”