The present invention provides a commercially viable process for the
preparation of highly pure and optically active L-(+)-lactic acid and
S-(-)-methyl lactate, in high yield, obtained from esterification of
aqueous crude lactic acid solution produced by sugar cane juice
fermentation broth and methanol in continuous counter current trickle
phase approach or in continuous counter current bubble column manner,
using stabilizers and the methyl lactate so obtained is recovered and
followed by purification of reasonably pure methyl lactate using reagent
mixture such as sodium bi-carbonate, mono-ethanolamine or
di-ethanolamine, urea or sodium-bicarbonate, mono-ethanolamine or
di-ethanolamine, thiourea to reduce the impurity of dimethyl ester of
dicarboxylic such as dimethyl oxalate or di-methyl succinate or methyl
ester of mono-carboxylic acid such as methyl pyruvate present as an
impurity, so as to get highly pure S-(-)-methyl lactate followed by
hydrolyzing highly pure S-(-)-methyl lactate using highly pure lactic
acid as a catalyst, using highly pure water as the hydrolysis media and
by using pre-treated activated carbon with dilute L-(+)-lactic acid, in
batch or continuous mode. This very high pure S-(-)-methyl lactate
constitutes an important product having interesting possibilities of
application at an industrial level, in pharmaceuticals. Highly pure
L-(+)-lactic acid thus obtained is used as an acidulant, as a food
additive, for pharmaceutical applications, a monomer for making
poly-lactic acid, as a monomer to prepare biodegradable polymer which are
useful for manufacturing bags, application films, in the field of
sanitary field, and has medical applications.