In an alcohol fermentation process, oil derived from biomass is chemically converted into an extractant available for in situ removal of a product alcohol such as butanol from a fermentation broth. The glycerides in the oil can be chemically converted into a reaction product, such as fatty acids, fatty alcohols, fatty amides, fatty acid methyl esters, fatty acid glycol esters, and hydroxylated triglycerides, and mixtures thereof, which forms a fermentation product extractant having a partition coefficient for a product alcohol greater than a partition coefficient of the oil of the biomass for the product alcohol. Oil derived from a feedstock of an alcohol fermentation process can be chemically converting into the fermentation product extractant. The oil can be separated from the feedstock prior to the feedstock being fed to a fermentation vessel, and the separated oil can be chemically converted to a fermentation product extractant, which can then contacted with a fermentation product comprising a product alcohol, whereby the product alcohol is separated from the fermentation product.