Simplified Method for Isolating L-Glutamic Acid from Kelp, (Laminaria japonica var. diabolica) by Crystallization at the Isoelectric Point after an Ion-exchange Resin Treatment.

Abstract

A simplified method is described for isolating L-glutamic acid crystals from kelp (Laminaria japonica var. diabolica) in college laboratories. Many impurities such as mannitol and minerals could be were successfully removed by an ion-exchange resin treatment, after which L-glutamic acid was crystallized at pH 3.2, which is the isoelectric point of L-glutamic acid. Paper chromatography gave an Rf value for the isolated L -glutamic acid that was identical with that of an L -glutamic acid standard and also with that of a mono sodium glutamate (umami seasoning) standard. This method has been used for experimental practice in food chemistry by third-grade students since 1996. The average yield of L -glutamic acid isolated from 50g of kelp (rausu konbu) was around 1g. This experimental method gives students a better understanding of amino acids and umami seasoning. It takes 3 or 4 hours and is suitable as a laboratory experiment in food chemistry.