Effects of Cooking Conditions on the Relationships Among Oxalate, Nitrate, and Lutein in Spinach

Abstract

This study sought to determine the optimal cooking conditions under which lutein would be maintained while oxalic acid and nitrate ion would be removed. The effects of cooking temperature and time control on the concentration of oxalic acid, nitrate ion, and lutein in spinach were investigated. The results demonstrated that boiling at 100°C for 2 min was the optimal cooking condition. This preserved approximately 77% of lutein while 67% of oxalic acid and 30% of nitrate ion were removed. If nitrate ion is disregarded, we also found that submerging in hot water at 60°C for 30 s was another optimal condition. In this case, 96% of lutein remained, 28% of oxalic acid was removed, whereas the content of nitrate ion was unchanged.