GREEN COLOR DEVELOPMENT IN POTATO COOKING WATER

The aim of this study was to determine the cause of green colour development in water used for cooking new potatoes. Evidence, from studies on rates of pigment formation, on spectral changes and on gel filtration chromatography, strongly favours chlorogenic acid and amino acids being involved. In particular, the reaction between chlorogenic acid and glutamine that occurs under mildly alkaline conditions, like those of the potato cooking water, led to a mixture of blue-green and brown pigments with properties similar to the green water colouring matter. Chlorogenic acid and asparagine gave a pigment mixture spectrally similar to the glutamine-derived pigment and may also contribute to the green cooking water colour.