Physical Changes of Frozen Fruits and Vegetables

Release time:

2022-12-19

With the popularity of refrigeration equipment, frozen food slowly into people's vision. Before the introduction of a lot of knowledge about frozen fruits and vegetables, today we introduce the content is still related to frozen fruits and vegetables, learn about vegetables and fruits in the process of frozen, what physical changes have taken place.
1, the collapse of cells.
It is well known that vacuoles are cells containing large amounts of water present in plant tissues. In the freezing process, it is easy to freeze into large ice crystals, resulting in greater pressure, and cells are vulnerable to rupture. On the other hand, the cell walls of plant tissues are relatively thick and lack of elasticity, and are easily punctured or burst by large ice crystals. The freezing treatment increases the permeability of the cell membrane or cell wall to moisture and ions. In the case of slow freezing, ice crystals are mainly formed in the intercellular space, which denature or irreversibly solidify the protein, the water in the cell is constantly flowing out, and the concentration of inorganic salts in the protoplast is rising.
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 in the cells remain supercooled, and the supercooled water in the cells has higher vapor pressure and free energy than the ice crystals outside the cells, thus prompting the water in the cells to move to the intercellular space and continuously combine with the ice crystal nuclei in the intercellular space. At the same time, the ice crystals formed by the intercellular space are getting larger and larger, resulting in mechanical extrusion, causing the separation of the original cells that are combined with each other. After thawing, the original state cannot be restored, and the water generated by the melting of ice crystals cannot be absorbed. The juice flows out, and the tissue becomes soft.