Phytochemical analysis of wastewater (nejayote) obtained after lime-cooking of different types of maize kernels processed into masa for tortillas

In order to generate value-added products from the wastewater (nejayote) of lime-cooked maize for tortilla production, we analyzed the phytochemical composition of six different types of kernels that were optimally cooked. Kernels, masas and nejayote solids were analyzed in terms of free and bound phenolics, ferulic acid and antioxidant (AOX) capacity. The germplasm analyzed included white (NWH), yellow (NYE), white quality protein (QPM), red (RED), high-carotenoid (HCA) and blue (BLU). Approximately 87, 82 and 91% of the phenolics associated to raw kernels, masa and nejayote were bound. Total phenolics of nejayote were about twice as much compared to kernels and masa. Lime-cooking reduced around 1/3 of bound ferulic in masa but enhanced at least 10 times the liberation of free moieties. The nejayote solids contained approximately 125 and 10 times as much free ferulic and 15 and 53 times more bound ferulic compared to kernels and masa. The nejayote solids contained approximately 40 and 8 times higher free and 191 and 61 times higher bound AOX capacities compared to those exerted by raw kernels and masa, respectively. Therefore, the nejayote solids are promising as a source of antioxidants which are known to promote health benefits and combat oxidative stress. (C) 2010 Elsevier Ltd. All rights reserved.