RESUMO
Justicia wynaadensis locally known as Moddu Soppu belongs to the family Acanthaceae. The aqueous bluish purple color extracted from the leaves and stems of Justicia is used in the preparation of a sweet dish by the natives of Kodagu district, Karanataka, India, exclusively during the monsoons. This traditional practice is believed to keep the people healthy throughout the year. Owing to its potential to be used as a natural colorant there is a strong need to develop efficient extraction method for maximum yield of colorant and preliminary scientific study of stability. Microscopy was carried out to find out the location of purple color in both leaves and stem and to study the anatomical details. An optimized microwave extraction method for extraction of colorant from Justicia has been developed. The microwave oven extraction yield of colorant is 9.41 % (±0.8598) under the optimized conditions of extraction time 30 min., extraction temperature 150 °C and ratio of liquid to solid 30 ml/g. The study demonstrated that the purple extract of the plant was stable against pH range 6.0-8.0, low temperature (4 °C), high temperature (≥50 °C) and sensitive to light. Thus these observations recommend the use of J. wynaadensis extract as a food colorant in neutral or slightly alkaline products (bakery, milk, egg etc.) and could be the potential source for the food colorant market.