NOVELTY - Producing a purified biodiesel from a feedstock (105), comprises (a) removing free fatty acids from the feedstock in a free fatty acid stripping process to produce a first refined feedstock and a fatty acid distillate, (b) transesterifying the refined feedstock to produce a first crude biodiesel, and (c) distilling the first crude biodiesel to produce the purified biodiesel and a distillation bottoms.    USE - The method is useful for producing a purified biodiesel from a feedstock including corn oil, palm oils, fatty acid distillates, distillation bottoms, brown grease, poultry fat, used cooking oil, pennycress oil, algae oil, soybean oil, and canola oil (all claimed).    ADVANTAGE - The method economically reduces problems associated with feedstocks having waxes, high free fatty acid levels, unacceptable color, high unsaponifiables levels, and high sulfur levels, and efficiently removes the unsaponifiable impurities to produce a higher quality biodiesel with improved physical and chemical properties.    DETAILED DESCRIPTION - Producing a purified biodiesel from a feedstock (105) comprises either (a) removing free fatty acids from the feedstock in a free fatty acid stripping process to produce a first refined feedstock and a fatty acid distillate, (b) transesterifying the refined feedstock to produce a first crude biodiesel, and (c) distilling the first crude biodiesel to produce the purified biodiesel and a distillation bottoms, or (a1) removing free fatty acids from the feedstock to produce a first refined feedstock and a fatty acid distillate, (b1) transesterifying the first refined feedstock to produce a first crude biodiesel, (c1) refining the first crude biodiesel to produce a first purified biodiesel, and (d1) esterifying the fatty acid distillate to produce a second crude biodiesel, (a2) refining the feedstock containing corn oil in a free fatty acid stripping process to produce a refined feedstock and a fatty acid distillate, (b2) transesterifying the refined feedstock to produce a crude biodiesel, and (b3) distilling the crude biodiesel to produce the purified biodiesel and a distillation bottoms.    DESCRIPTION OF DRAWING(S) - The figure shows a flow diagram of the method of biodiesel production.    Feedstock (105)    Strong base (215)    Centrifugal separator (220)    Soap stock (225)    Bleaching and polishing units. (230)