With the popularization of refrigeration equipment, frozen food has gradually entered peoples vision. We have introduced a lot of little knowledge about quick frozen fruits and vegetables before, but todays content is still related to quick frozen fruits and vegetables. Lets know what Physical change have taken place in the process of quick freezing of vegetables and fruits.

1. The breakdown of cells.

As is well known, vacuoles are cells that contain a large amount of water in plant tissues. During the freezing process, it is easy to freeze into large ice crystals, generating significant pressure and making cells susceptible to rupture and damage. On the other hand, the cell walls of plant tissues are relatively thick and lack elasticity, making them prone to being punctured or expanded by large ice crystals. Freeze treatment increases the permeability of cell membranes or walls to water and ions. Under slow freezing, ice crystals are mainly formed in the intercellular space, causing protein denaturation or irreversible coagulation. Water inside the cell continuously flows out, and the concentration of inorganic salts in the protoplast continuously increases.

2. Mechanical damage.

The first to form ice crystals is the free water in the intercellular space, which generally contains less soluble substances and has a high freezing point. However, the protoplasts inside the cells remain in a supercooled state, and the supercooled water inside the cells has a higher vapor pressure and free energy than the ice crystals outside the cells, thereby promoting the movement of water inside the cells towards the intercellular space and continuously binding to the ice crystal nucleus in the intercellular space. At the same time, the ice crystals formed in the intercellular spaces become larger and larger, causing mechanical compression, causing the previously bound cells to separate. After thawing, they cannot return to their original state, absorb the water generated by the melting of ice crystals, and flow out juice, resulting in tissue softening.