1070-4272/04/7702-0254 C 2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 2, 2004, pp. 254!259. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 2, 2004,
Original Russian Text Copyright + 2004 by Konovalova, Novikov, Stepanova, Reut.
OF CHEMISTRY AND TECHNOLOGY
Recovery of Lipids from Aqueous Dispersions
with Chitosan Solutions
I. N. Konovalova, V. Yu. Novikov, N. V. Stepanova, and K. V. Reut
Murmansk State Technical University, Murmansk Russia
Knipovich Arctic Research Institute of Fishery and Oceanography, Murmansk, Russia
Received July 10, 2003
Abstract-Binding of lipids from aqueous protein-lipid suspensions with a natural polysaccharide, chitosan,
was studied in order to develop a procedure for removal of impurities from water. The physicochemical nature
of this process was analyzed. The mechanism involving formation of structurally ordered chitosan precipitates,
and adsorption and solubilization of lipids with chitosan macromolecules was discussed. The best conditions
for defatting of aqueous protein-lipid dispersions with the aid of chitosan were determined.
Removal of proteins and lipids from industrial waste-
water is being studied extensively. The conventional
physicochemical procedures used to remove proteins
and lipids from aqueous dispersions with high content
of these impurities (e.g., wasterwater of fish industry
and hydrobiont reprocessing) are sorption on various
sorbents and flotation with preliminary coagulation of
proteins and lipids with inorganic electrolytes and mac-
romolecular flocculants. Inorganic coagulants, such
as aluminum and iron salts, calcium compounds, and
dry lime, are ineffective for purification of aqueous
dispersions with low lipid content (e.g. protein hy-
drolyzates). Moreover, some of these compounds are
toxic. Proteins and lipids recovered with the aid of
synthetic flocculants (e.g., polyacrylamides and poly-
meric quarternary ammonium salts) cannot be used as
forage additives without additional purification [1, 2].
Hence, a search for new nontoxic biodegradable re-
agents suitable for exhaustive removal of peptides and
lipids from aqueous dispersions is a topical problem.
Natural macromolecular polysacharides including a
cationic polysacharide, chitosan, can be used for this
purpose. Chitosan is produced by deacetylation of
the natural biopolymer, chitin ; it consists of res-
idues of 2-deoxy-2-amino-D-glycose bound via b-1,4-
bonds. Chitosan contains reactive free amino groups.
This polysacharide coagulates peptide-lipid colloids
 and can be used for efficient recovery of lipids
from aqueous dispersions , e.g., from peptide hy-
drolyzates. Peptide hydrolyzate is a dispersion con-
taining low-molecular-weight peptides, suspended sub-
stances, free amino acids, and lipids. Peptide hydro-
lyzates are mainly used for preparing microbiological
culture media [8, 9]. Lipids and, in particular, fatty
acids are toxic for most of bacterial cultures .
The interaction mechanism in the systems contain-
ing peptides and lipids and macromolecular compounds
has been recently studied . It is known 
that macromolecular compounds can solubilize small
amounts of oleophilic compounds to form colloids.
Probably, the solubilization of lipids can affect the
quality of purification of peptide hydrolyzates with
The aim of this study was to examine sorption
of lipids from aqueous peptide-lipid dispersions on
chitosan and to determine the physicochemical mech-
anism of this process.
Protein hydrolyzates of wastes from processing of
northern shrimp fishery (SFW), king crab (KCW),
Icelandic comb (ICW), and sea cucumber (cucumaria)
(CW) were prepared and characterized by the con-
ventional procedures [14, 15]. The wastes were treated
with a Model 1094 (Tecator) homogenizer. The pro-
teins were hydrolyzed for 6 h in the presence of pro-
teinases at 50oC and a protein : water weight ratio of
1 : 1. Proteinases were synthesized from hepatopan-
crease of king crab [16, 17].
Protein hydrolyzates were treated with chitosan
solutions in the ratio of 0.12531.000 g of the polymer