Impact of cooking methods on folates, ascorbic acid and lutein in green beans (Phaseolus vulgaris) and spinach (Spinacea oleracea)

Folates, ascorbic acid (vitamin C) and lutein (antioxidant carotenoid) concentrations were determined after cooking (boiling and steaming) fresh, frozen and canned green beans (Phaseolus vulgaris) and spinach (Spinacea oleracea). The aim of this study was to qualify and quantify the loss of water soluble (folates and ascorbic acid) and lipid soluble (lutein) micronutrients in the cooked products and liquids and the canning liquor. In canned products, folates were found in the canning liquor. Boiling regardless of product reduced plant tissue folates and ascorbic acid but not lutein concentrations. Loss of folates during boiling occurred due to leaching (diffusion) and ascorbic acid due to temperature (heating). Steaming reduced ascorbic acid but not folate or lutein concentrations. (C) 2012 Elsevier Ltd. All rights reserved.