Fortification of food systems using modern biotechnology represents an exciting approach to improve health in different human sectors that require an increased dietary intake of specific nutrients [1]. One of these nutrients, folate (vitamin B9), is an important intermediate in cellular metabolism. Its deficiency has been linked to severe health problems, both in infants and adults [2]. Therefore, we examined a relevant food system, wine fermentation, for folate. We measured folate in commercial wines, and found variable levels of this vitamin. Lab-scale fermentations revealed that folate levels were determined primarily by the yeast used to ferment the wine, with a dependence on the particular strain used. We also undertook the bioengineering of yeast to determine if folate concentration in wine could be increased. Using molecular techniques, overexpression of two folate biosynthesis genes in wine yeast was undertaken. Overexpression of FOL2, but not ABZ1, resulted in elevated folate levels in wine. Our results demonstrate the utility of bioengineering yeast for the vitamin fortification of wine. (C) 2015 Elsevier Ltd. All rights reserved.