Natural
Grade carrageenan consists of linear-sulfated
polysaccharide of D-galactose and 3,6-anhydro
D-galactose obtained from Eucheumacottonii
and E.spinosum
farmed in the shallow lagoons of the Philippine
islands.
The
different types of carrageenan differ only
in the position and number of ester sulfate
groups which determine the physical properties
(viscosity and gelation characteristics) of
the carrageenan.
The
visco-elasticity of the sol and gel phases
can be varied to suit almost any application.
Viscosity
is a measure of the amount of shearing stress
or liquid resistance to flow by a fluid or semi
fluid.
For
carrageenan solutions, the measured viscosity
is affected by factors such as temperature, presence
of cations and degree of gum hydration.
When
the carrageenan powder is dispersed in water at
room temperature, the particles absorb water leading
to swelling and increase in size as the particles
start to hydrate.
With
heating, the hydrated molecules uncoil and tend
to intertwine with adjacent particles forming
a viscous solution.
As
the temperature increases , swelling increases
and so does the measured viscosity as the particle
becomes fully swollen.
Further
heating eventually leads to complete dissolution
of carrageenan which leads to a decrease in viscosity.
At temperatures
higher than 60° C, carrageenan exists in
solution as a random coil which undergoes
a double helix transition as the temperature
decreases.
Gels
form when the double helices align to form
quasi-crystalline regions.
The
ability of carrageenan to form a gel and the characteristics
of the gel formed, is related to how closely the carrageenan molecules can align
to form a quasi-crystalline network.
The
presence of ester sulfates tends to keep the molecules
apart thus the need for cations to act as a bridge
between two molecules.
The functionality of carrageenan
is sensitive to both the type and concentration
of cation.
Of
the three types, lambda is the least salt
sensitive (lambda is non gelling) and kappa
the most. The physics behind is not well defined.
Carrageenan
is a highly negatively charged macromolecule and
has the ability to interact with any species carrying
an opposite charge.
Molecules
with positively charged groups (e.g., proteins
below the isoelectric point) will complex directly
with carrageenan without the need for intervening
cations.
Above the isoelectric point, cations are required
to form an electrostatic bridge between the protein
and carrageenan.
The
details of the interaction depend critically on
the stereochemistry of the protein.
Carrageenan
is compatible with all ingredients normallyused
in the food industry
Insensitive
to enzymes including cellulase
and can be used safely with other
gums such as CMC, which are enzyme
sensitive.
Bland
with excellent flavor release
characteristics.
The
properties of a mixed gum system
are generally the sum of the individual
components except for a few gums
which exhibit a positive synergism
with carrageenan.
Carrageenan
interacts with finely divided insoluble
materials (i.e., calcium carbonate or
silica) to give a stable dispersion
of the particulates.
An
interaction will take place between
carrageenan and any substrate which
is either positively charged, has positively
charged regions or a positive electrical
double layer.
These
interactions are very beneficial for
the stabilization of systems containing
particulates or other insolubles. (i.
e., in dentrifice application).
All
types of carrageenan can be dissolved
in water/polyol mixes.
The
water/polyol ratio required depends
on the carrageenan, polyol and ionic
environment.
Carrageenan/
polyol systems exhibit unique rheology
which can be used to control the stability
and organoleptic properties of any preparation
containing polyols.
Iota
carrageenan in water/polyol systems
form true thixotropes with well-defined
yield points.
Kappa
carrageenan in water/polyol systems
form gels with a well-defined break
point.
The
interaction with polyols has been extensively
used in cosmetic and pharmaceutical
preparations.
Carrageenan
is produced with specific yield point
that can be tailored to a given application.
Suspending power depends on choice of
carrageenan as well as concentration.
Carrageenan
gels in the presence of all common cations,
requires no refrigeration and produces
a very wide range of texture and mouthfeel.
Pectin,
including low-methoxy pectin, requires
sugar for gelation.
Gelatin
requires refrigeration for gelation and
cannot provide a range of texture. It
is not kosher.
Xanthan
suspends and its ending power can be increased
only by increasing gum concentration.
Propylene
glycol alginate solutions have a yield
point and will therefore suspend particulates.
However, there are considerable concerns
over the safety of derivative alginate.
Alginates
require calcium for gelation and have
a limited range of texture and mouthfeel.
Starches
suspend by viscosity alone. Starch gels
are pasty in texture and mask flavor.
Carrageenan
is unlike simple salts or sugar which
simply dissolves if added to water.
Carrageenan
powders are composed of finely ground
dehydrated gels which must swell before
dissolution can take place.
The
dehydrated gel fragments are hard and
completely non-tacky.
Dispersion
Techniques:
Partially
swollen materials become very
sticky. It is thus essential to
ensure that efficient and proper
dispersion is effected before
appreciable swelling occurs.
This
is accomplished easily by dry
blending the carrageenan with
the other
dry
ingredients or by wetting with polyol before addition to water.
If
carrageenan is to be added directly
to water, it should be added to
the vortex of a well-stirred system.
If
the system allows, never add carrageenan
to hot water.
Carrageenan
systems require heating to achieve optimum
utilization unless the carrageenan blend
is designed for cold functionality.
In
meat systems, where low viscosity solutions
are required for pumping purposes, carrageenan
is dispersed after the salts have been
dissolved, to inhibit swelling of the
particle and to prevent clogging of
the syringe.
If
the desired product is in a gel state,
as in dessert gels, the gel matrix should
not be disturbed during cooling so as
not to disrupt the gel formation.
For
suspension applications such as salad
dressings or marmalades, gentle shear
of the system during cooling may be
used to improve the texture of the product
and create body.
For
low pH processing, such as juices or
tomato sauce, carrageenan should be
added at the end of the cooking cycle
with fast cooling to prevent degradation
in acidic medium.
Carrageenan
powders contain 8-10 % moisture, most
of it bound to the molecule. It does
not absorb moisture from the atmosphere
or cause other ingredients to cake.
The
dry powder may be stored for a year
or more under standard warehousing conditions
without deterioration or loss in quality
so long as it remains dry.
Unlike
other gums, carrageenan is insensitive
to enzymes, especially cellulase.
In
both gel and solution form, food preservatives
must be added to prevent bacterial contamination,
which may cause fermentation and eventually,
the degradation of the carrageenan.
However, aseptically packed products
do not require preservatives.
Carrageenan
is highly stable in boiling neutral
or alkali solutions without loss in
viscosity or gel potential.
In
acidic systems, carrageenan solutions
are susceptible to viscosity losses
specially at high cooking temperature.
In
gel form, carrageenan is stable even
at low pH.
Natural
Grade Carrageenan may be used in various
food and nonfood applications where the
formulator requires a stabilizer or needs
to impart or maintain a specific texture
or viscosity. The list of applications
is endless.
