TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The means for adding the monoalcohol, is an aerator for liquids, where the aerator is configured and designed for the addition of monoalcohol (preferably 1-4C monoalcohol). The aerator comprises: a rotor having a rotational axis and a stator surrounding the rotor; and an inlet for the monoalcohol, where the monoalcohol is supplied to the rotor in the direction of its rotational axis. The stator comprises a ring opening, which is configured and designed for removing the alkyl ester present in the lower region of the reactor, where: the stator comprises many flow channels; each of the flow channel comprises a radial inner inlet opening and a radial outlet opening, with respect to the rotational axis; and the flow channels are configured and designed for receiving and guiding the mixture of monoalcohol and alkyl ester transported from the rotor.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The step (c) is carried out in the presence of an acid catalyst (preferably sulfuric acid or p-toluene sulfonic acid) and/or the step (d) is carried out in the presence of a basic catalyst (preferably potassium hydroxide, sodium hydroxide or sodium methylate). The process comprises the step (f), after the step (e), of purifying the alkyl ester, where the purification is carried out by distillation (preferably vacuum distillation at 30-80 mbar). The vacuum distillation is carried out at 195-280 degrees C. The added monoalcohol is evenly distributed over the reactor cross-section. The monoalcohol liquid is applied in the form of droplets, vapor or bubbles into the reactor, where the droplets and/or bubbles exhibit a diameter of less than 5 (preferably, round, 2) mm. Preferred Components: The starting mixture comprises optionally used or optionally purified vegetable-, animal- or technical-oils and/or fats (preferably soapstock, brown grease, yellow grease, tallow oil, lard oil, frying oil, edible fats, edible suet, crude vegetable oils (including rapeseed oil, colza oil, soy oil, sunflower oil, palm oil, corn oil, cottonseed oil, palm kernel fat or coconut oil) and/or animal fat). The unpurified fatty acid glyceride starting mixture is purified before adding into the reactor, where the step of purifying comprises the removal of water content. The monoalcohol includes 1-4C monoalcohol (preferably methanol). EXAMPLE - None given.