The present invention explains a realistic and effective process for isolating and purifying carotenoids containing higher concentrations of carotenoids such as trans-lutein, trans-zeaxanthin, Cis-lutein, .beta.-carotene and Cryptoxanthin from Marigold flower petals under controlled conditions leaving no traces of any organic hazardous solvents. The process involves ensilaging Marigold flowers, dehydration, solvent extraction, alkali hydrolysis of carotenoid esters with absolute alcohol, crystallization/purification using water, absolute alcohol mixture followed by filtration and drying until the crystals are considerably free from moisture and absolutely free from residual hazardous solvents. These crystals are suitable for nutraceutical and food products as supplements.