Colour and Cooking: Chlorophyll

The effect of an alkali, whether already present in the cooking water or added in the form of bicarbonate of soda, is to prevent the replacement of the central magnesium atom in chlorophyll with hydrogen. The vegetable then acquires an unnaturally bright green colour. Some might find this attractive, but the penalties to be paid are formidable. Not only is there a heavy loss of vitamin C, but the cell walls of the vegetable are disrupted and it becomes mushy, even slimy. So it is best to avoid alkaline water and not to add bicarbonate of soda.