Fermentation of Corn By-Products: From Agrifood Waste to Higher Value Antioxidant Products

To improve the nutri-functional quality and, in particular, the antioxidant capacity of corn by-products, fermentation with selected lactic acid bacteria was carried out. To this purpose, white-1 and 2 and yellow corn by-products were fermented and then extracted. In all the samples, the fermentation process shows an improvement in antioxidant activity in comparison to non-fermented by-products. It was observed that the yellow corn by-product extracts have a higher content of total phenols, especially after fermentation with P. pentosaceus, while for white-1 corn by-product extracts, an increment of antioxidant capability was noticed when fermented with L. plantarum. The antioxidant capacity was measured with DPPH and ABTS(+) assays, showing that yellow corn extracts are more active in comparison with white-1 and white-2 ones. Moreover, L. plantarum and P. pentosaceus provided the best results in increasing the antioxidant activity in all the samples. Analyzing lipid peroxidation in the presence of fermented white-2 corn by-product extracts, we observed an inhibition of the process after treatment with L. citreum compared to the non-fermented control. In all the analyzed samples, through LC-DAD-ESI/MS analysis, the antioxidant dicoumaroyl spermidine (DCS) was detected. The abundance of antioxidant molecules was higher in samples fermented with P. pentosaceus, confirming previous observations.