The 2012 ASHS Annual Conference

Lettuce is an important leafy vegetable crop grown in worldwide food systems with the United States ranking second behind China in total production. In 2009 the USDA Food Economic Research Service reported 1,057,715 hectares of lettuce grown in the world. Metabolites such as nitrate and polyphenolics accumulate in lettuce and their potential effect on human health should be considered. Nitrate accumulation in leafy vegetables may have detrimental effects on human health including methaemoglobinaemia and carcinogenesis. Many polyphenolic compounds are considered antioxidants and present positive health benefits when included in human diets. There are four main types of lettuce and numerous cultivars within each type. Because these metabolites may vary significantly between lettuce types and/or cultivars, 45 cultivars of lettuce, representing the four types, were grown in the field under best management practices at the LSU AgCenter’s Burden Center in Baton Rouge, LA, during Fall 2011. The top two highest yielding cultivars of head, butterhead, and romaine types and the top three highest yielding leaf types were analyzed for nitrate concentration and total phenolic compounds. Two classes of polyphenolic compounds, caffeic acid derivatives and flavonols were identified in all types. Results suggest there are considerable differences in these metabolites between types and varieties and this information should be considered by producers and consumers.