Figure 1
Introduction Cell membranes consist of a phospholipid bilayer combined with a variety of proteins in a fluid mosaic arrangement. Cell membranes are selectively permeable. Some solutes cross the membrane freely, some cross with assistance (facilitated diffusion), and others do not cross at all. Upon heating, the structure of the cell membrane may be damaged and the permeability increases. Anthocyanins are naturally occurring compounds that give color to fruit, vegetables and plants. They give red color to buds and young shoots and the purple and purple-red colors of autumn leaves. Anthocyanins are the pigments thought to play a major role in the high antioxidant activity levels observed in red and blue fruits and vegetables. The color and stability of an anthocyanin in solution is highly dependent on the pH. They are most stable and most highly colored at low pH values and gradually lose color as the pH increases. This characteristic limits the application of anthocyanins as a food colorant to products with a low pH. In this experiment we follow the effect of heating on the permeability of beet cell membranes by using a Colorimeter to measure the amount of anthocyanins released to the surrounding solution.