What effect does temperature have on the permeability of beetroot cell membrane?

Effect of Heat:

When you heat a beetroot, you disrupt the cell membranes. A biological membrane is made of a so-called phospholipid bilayer. These are formed because the phospholipids that make it up have a polar "water-loving" (hydrophyllic) head and a "water-hating" (hydrophobic) tail. The tails pack together, exposing only the polar heads to the water. The most effective way of doing this is to create two blankets one atop the other, with the fatty acid tails towards each other. This is the phospholipid bilayer.

In a cell they form sacks. One goes all around the cell (the plasma membrane), others may form vacuoles (such as the tonoplast). Yet others may be like stacks of half empty bags (the endothelial reticulum, which is also continuous with the nuclear envelope. In these lipid seas, there will be a number of proteins in various degrees of submersion. Some span all the bilayer, thus being exposed on both sides. Others just drift on either of its surfaces. Typically, you will find that about 70% of a cell membrane is protein. The water around and within the compartments formed by the phospholipid bilayers is also crammed with protein (= cytoplasm).

So what happens when you heat this? When you heat something you give it energy. Molecules start to spin and vibrate faster. The water will expand too. This will have a disruptive effect on any membrane in its way. To make things worse, lipids become more fluid as temperature goes up (think of what happens when you heat butter) so the membranes become more fragile.

Proteins are remarkable machines: they're formed of coiled and folded strings of amino-acids, held together by hydrogen bonds and disulphide bridges. If you heat them too much, they will untangle and break apart (vibrations again). When this happens to the proteins spanning a lipid membrane, they will form holes that will destroy the delicate structure. Now, any pigments in the innermost compartment will spill out.

So summing it all up; the higher the temperature the more the beetroot cell membrane will be damaged releasing more dye

Resourse: www.biologymad.com/resourcesbeetroot%20pigment2.doc