Patent ID: 7507561

Claim:
A process for producing polylactic acid from fermentation of renewable agricultural feed stocks comprising molasses or cane bagasse employed as a starting material containing sugars with all other substances present in molasses and cane bagasse, together with a nitrogen source selected from corn steep liquor, and autoclaved yeast paste, the process comprising the steps of; i) preparing a fermentation medium having molasses as a carbon source; ii) fermenting said fermentation medium; iii) extracting lactic acid from said fermentation medium using organic solvent and back extracting into the aqueous phase using hydroxide of ammonia, alkali or alkaline earth metal; iv) purifying said lactic acid solely with cation exchange resin, and concentrating said purified lactic acid; v) preparing lactide from said lactic acid; vi) polymerizing said lactide to form said polylactic acid; wherein vii) said renewable agricultural feed stock is cane molasses containing about 40% to about 50% (w/w) fermentable sugar; and viii) said renewal agricultural feed stock comprises cane bagasse, and including preparing said cane bagasse by hydrolyzing said bagasse particles with dilute acid for 30-90 min at 120° C. and treating said bagasse with 1-5% (w/v) alkali at 120° C. to 150° C. for a period of about 15 to about 90 minutes for delignification.