Effects of steaming, boiling and frozen storage on carotenoid contents of various sweet corn cultivars

The effects of domestic cooking methods and frozen storage on lutein, zeaxanthin, β- cryptoxanthin, β-carotene and total carotenoid contents of various corn cultivars were investigated. New hybrid small-ear corns (KKU#1WY, KKU#2WY and KKU#3YY) were analyzed for carotenoid contents compared to commercial big-ear corns (ATS5 and Hybrix3). Total carotenoid contents of fresh and cooked sweet corns ranged from 1.52-5.72 to 4.41-10.67 μg/g, respectively. Lutein and zeaxanthin were the predominant carotenoids in raw, cooked and frozen sweet corns. The cooking methods resulted in a significant increase in the concentration of total carotenoids (41.33-179.93%), lutein (35.51-232.18%), zeaxanthin (48.12-457.16%), β-cryptoxanthin (22.35-405.03%) and β-carotene (15.82-88.16%) for all cultivars, except the Hybrix3 in which the β-carotene content decreased after steaming and boiling (p 0.05). Blanching prior to freezing also caused increase in corn carotenoids. All corn cultivars showed decreases in lutein, zeaxanthin, β-cryptoxanthin and β-carotene contents during frozen storage at -20°C for 1 month.