Production of alcohol esters and in situ product removal during alcohol fermentation

A method comprising:

• (a) contacting butanol produced in a fermentation process with at least one exogenous carboxylic acid and at least one extracellular enzyme capable of esterifying the carboxylic acid with the butanol to form butyl esters of the carboxylic acid;
• wherein the carboxylic acid in the fermentation process is present at a concentration sufficient to produce a two-phase mixture comprising an aqueous phase and a butyl ester-containing organic phase;
• (b) separating the butyl ester-containing organic phase from the aqueous phase;
• and
• (c) recovering butanol from the butyl esters.

A method for producing butanol and butyl esters from a feedstock comprising:

• (a) providing a feedstock;
• (b) liquefying the feedstock to create a liquefied biomass comprising oligosaccharides;
• (c) separating the feedstock slurry to produce a product comprising an aqueous stream, an oil stream, and solids;
• (d) adding the aqueous stream to a fermentation vessel containing a fermentation broth
• (e) saccharifying the aqueous stream;
• (f) fermenting the saccharified aqueous stream to produce butanol and concurrently contacting the butanoi with at least one exogenous carboxylic acid and at least one extracellular enzyme capable of esterifying the carboxylic acid with the butanol to form butyl esters of the carboxylic acid wherein the carboxylic acid is present at a concentration sufficient to produce a two-phase mixture;
• (g) separating the butyl ester-containing organic phase from the aqueous phase;
• and
• (h) recovering butanol from the butyl esters;
• and optionally steps (e) and (f) occur concurrently.