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INTRODUCTION TO


WHAT IS "CARRAGEENAN"?
Carrageenan is a linear sulfated polysaccharide obtained from red seaweeds.

Has the unique ability to form a wide range of gel texture at room temperature, firm or elastic, with high or low melting point.
Gelation requires no refrigeration and the gels can be made stable throughout repeated freeze-thaw cycles.

Thickens, suspends and stabilizes particulates as well as colloidal dispersions and water/oil emulsion.

Solutions shear thin (providing ease of pumping), but viscosity and suspending ability is quickly restored on standing.

Table of Contents:
PHYSICAL CHEMISTRY: COMPARISON With OTHER GUMS
Chemical structure  
Viscosity of carrageenan solutions USE OF CARRAGEENAN:
Gelation of carrageenan Dispersion Techniques
Sensitivity to cations Hydration of carrageenan
Protein reactivity Process Considerations
Compatibility with other ingredients
    and gums
Stability of carrageenan powder
Interaction of carrageenan with particulates  
Interaction between carrageenan and polyol FOOD & NONFOOD APPLICATIONS


Regulatory Status of Philippine Natural Grade Carrageenan (PNG):

On July 8, 1991, the USFDA has confirmed that PNG carrageenan complies with 21 CFR No. 172.620 and is therefore acceptable for use as food additive for human consumption in the United States.

In 1994, JECFA (Joint Expert Committee on Food Additives) and CCFAC (Coded Committee on Food Additives and Contaminants) in Rome, after conducting respective toxicological assessment cleared PNG as food additive. Consequently, Codex Alimentarius has assigned INS 407a to the product.

WHAT IS THE PHYSICAL CHEMISTRY OF CARRAGEENAN?

Chemical structure:

Natural Grade carrageenan consists of linear-sulfated polysaccharide of D-galactose and 3,6-anhydro D-galactose obtained from Eucheuma cottonii and Eucheuma 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.

KAPPA

IOTA

LAMBDA

Viscosity of carrageenan solutions:

 

Carrageenan contributes to viscosity development.
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.

Gelation of carrageenan:
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.
Requires the presence of cations for alignment.

Sensitivity to cations:

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.

Sensitivity to cations:
KAPPA : Na+ << Ca++ < K+
IOTA : Na+ << K+ < Ca++

Protein reactivity:

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.
The interaction can lead to :
the precipitation of the protein
to the formation of a stable complex or gel 
structure with interesting and useful properties; 
(e.g., milk/ carrageenan.)

Compatibility with other ingredients and gums:

Carrageenan is compatible with all ingredients normally used 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.
Kappa and locust bean gum are synergistic.
 

Interaction of carrageenan with particulates:

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).
 

Interaction between carrageenan and polyol:

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.

HOW DOES CARRAGEENAN COMPARE WITH OTHER GUMS?

Gum

Viscosity

Suspension

Gelation

Emulsion Stabilization

Milk/protein reactivity

Carrageenan

3

3 (1)

3 (2)

3

3

CMC

3

5

5

5

5

Pectin

3

5

3 (3)

5

5

Gelatin

5

5

3 (4)

5

5

Xanthan

3

3 (5)

5

3

3

Alginates

3

5 (6)

3 (7)

5

5

Starches

3

5 (8)

3

5

5

  1. 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.
  2. Carrageenan gels in the presence of all common cations, requires no refrigeration and produces a very wide range of texture and mouthfeel.
  3. Pectin, including low-methoxy pectin, requires sugar for gelation.
  4. Gelatin requires refrigeration for gelation and cannot provide a range of texture. It is not kosher.
  5. Xanthan suspends and its ending power can be increased only by increasing gum concentration.
  6. Propylene glycol alginate solutions have a yield point and will therefore suspend particulates. However, there are considerable concerns over the safety of derivative alginate.
  7. Alginates require calcium for gelation and have a limited range of texture and mouthfeel.
  8. Starches suspend by viscosity alone. Starch gels are pasty in texture and mask flavor.

HOW IS CARRAGEENAN USED?

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.

Hydration of carrageenan:

The hydration of carrageenan is critically dependent on the ionic environment.
Addition of salts decreases cold swelling.
As the concentration of added salts increases, the cold swelling decreases and the temperature required to completely solubilize the gum increases.

Process Considerations:

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.

Stability of carrageenan powder:

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.

WHEN AND WHERE TO USE CARRAGEENAN?

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.

FOOD APPLICATIONS

Processed Meat > substitutes fat and serves as meat extender and binder; enhances juiciness;increases yield; prevents fat separation
Processed Poultry > controls dehydration while frozen; enhances juiciness and increases yield
Milk/Chocolate Milk Drink/Juice > stabilizes and improves viscosity
Ice Cream > prevents large ice crystal formation; enhances excellent flavor release
Flan/Dessert Gel/Confectionery >- serves as gelling agent; enhances flavor release and excellent mouthfeel
Bread/ Noodle/Pasta > increases yield and improves texture and mouthfeel
Cakes/Pastries > substitutes butter and improves texture and mouthfeel
Sauce/Salad Dressing > thickens and improves viscosity
Beer/Wine/Vinegar > accelerates and improves clarity

NONFOOD APPLICATIONS

Canned Petfood >
Moist meat > serves as gelling and stabilizing agent
Moist whole fish > serves as binder
Personal Care/Pharmaceutical > serves as thickener/stabilizer/binder
Culture Media > serves as gelling agent and stabilizer


 
 
 
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