Why does a vegetable become soft and collapse when placed in very salty water?

When a vegetable is placed in very salty water, the water molecules are drawn out of the vegetable by osmosis, which is the movement of water across a semi-permeable membrane. This causes the vegetable to become soft and collapse.

Osmosis occurs when there is a difference in concentration between two solutions separated by a semi-permeable membrane. The water molecules move from the less concentrated solution (the vegetable) to the more concentrated solution (the salt water).

The cell membrane of the vegetable acts as a semi-permeable membrane, allowing the water molecules to pass through but not the larger molecules, such as the cell contents. As the water moves out of the vegetable, the cells become less turgid and the vegetable starts to wilt. Eventually, the cells will collapse and the vegetable will become soft.

The amount of time it takes for a vegetable to become soft and collapse in very salty water depends on the type of vegetable and the concentration of the salt water. Vegetables with a high water content, such as lettuce and cucumbers, will soften more quickly than vegetables with a low water content, such as carrots and potatoes. The higher the concentration of salt water, the more quickly the vegetable will soften.

Adding salt to water is a common way to preserve food because it draws the water out of the food. This makes it more difficult for bacteria to grow and spoil the food.