abstract
Glutamic acid (Glu) has potential as feedstock for bulk chemicals production. It has also
been listed as one of the top twelve chemicals derived from biomass. Large amounts of
cheaper Glu can be made available by enabling its production from biomass by-products,
such as wheat dried distillers grains with solubles (DDGS) derived from ethanol produc-
tion. The aim of this study was to develop a new method for Glu production from biomass.
Wheat gluten was used to represent wheat DDGS. To reduce chemicals usage, several
methods were evaluated. These included enzymatic, dilute acid, and a combination of
enzymatic and dilute acid hydrolysis. The separate enzymatic and dilute acid hydrolysis
(1 M HCl; 95 C) resulted in yields of 48% and 46% Glu, respectively. However, the combi-
nation of enzymatic and dilute acid hydrolysis resulted in a much higher yield of 70% Glu
and 10% pyroglutamic acid thereby opening up new possibilities for the industrial pro-
duction of Glu from biomass.1. Introduction
The biorefinery and biobased economy concepts promote the
utilisation of biomass and residues to produce bio-based
products and create more value from plant production
chains. With this, society will benefit ecologically and
economically. Ecologically, the use of biomass will reduce the
use of fossil raw materials. Economically, biomass has lower
price compare to that of fossil raw material [1]. Recently there
are numerous reviews or roadmaps exploiting the use of
lignocellulose for producing biobased platform chemicals [2].
PNN/NREL (Pacific Northwest National/National Renewable
Energy Laboratory) roadmap reported the top twelve
chemicals derived from biomass sugar, which included glu-
tamic acid (Glu) [3]. The possibility of valorizing Glu to bulk
chemicals through its decarboxylation using Glu a-decarbox-
ylase has been shown recently [4]. Another method of Glu
decarboxylation, via electro-oxidative, could also be used for
valorizing Glu [5]. Examples of chemicals that have been
synthesized from glutamic acid include N-methylpyrrolidone,
succinonitrile, pyrrolidone, and N-vinylpyrrolidone [6].
Glu production from sugar can be done via fermentation,
but still needs improvement in microbial catalysis. Alterna-
tively, Glu can be produced from biomass protein. A recent
review on availability of protein-derived amino acids shows
that Glu is abundantly available in protein from several
biomass by-products, including wheat dried distillers grains