cheese whey with chitosan demonstrated that the optimum
percentage of chitosan suspended solids was 2±
2.5% at pH 6. This corresponded to chitosan concentrations
of 49±62 mg/L for whey containing an
average concentration of 2270 mg/L of suspended solids
(SS). A 90% reduction in SS was achieved by this
treatment [30]. Greater reductions in turbidity of cheese
whey were observed as chitosan concentration was
increased [93]. The in¯uence of dierent factors such as
ionic strength, pH, size of the drops in the emulsion,
relative concentration of oil and emulsi®er and type of
emulsi®er on the dose of chitosan necessary to obtain
¯occulation of the model food oil/water emulsion was
observed by Pinotti et al. [35]. These authors reported
that the increase in NaCl concentration reduces the dose
of chitosan necessary to produce destabilization and
¯occulation. The longer the surfactant chain length, the
greater the tendency toward polyelectrolyte association,
therefore the greater was the chitosan dose to reach zero
charge.
Application of chitin and chitosan for puri®cation
of water
Better awareness of the ecological and health problems
associated with heavy metals and pesticides and
their accumulation through the food chain has prompted
the demand for puri®cation of industrial waste
waters prior to their discharge or use [36, 94]. Conventional
methods for the removal of metals from industrial
waste water, may be ineective or expensive,
especially when metals are available at low concentrations
[39, 95].
Chelation ion exchange is a technique which can be
used to recover metal ions from waste water. Commercially
available and environmentally safe biopolymers
are capable of lowering transition metal ion concentrations
to parts per billion levels. Such biopolymers
possess a number of dierent functional groups, such as