FOOD CHEMISTRY Gums

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FOOD CHEMISTRYGums

• BY
• DR BOOMINATHAN Ph.D.
• M.Sc.,(Med. Bio, JIPMER), M.Sc.,(FGSWI, Israel),
  Ph.D (NUS, SINGAPORE), PDF (USA)
• PONDICHERRY UNIVERSITY
• Sixth lecture
• 17/August/2012

Source Collected from different sources on the
internet and modified by Dr Boominathan Ph.D Ref.
Food chemistry by Fennema .
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Goals

• Structural arrangements of different Gums
• Meska
• Xanthan
• Composition
• Physico-chemical properties of Meska Xanthan
• Applications of Gums in food industry

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Gum arabic/acacia gum/meska
When the bark of some trees and shrubs is
injured, the plants exude a sticky
material that hardens to seal the wound and give
protection from infection and desiccation. Such
exudates are commonly found on plants that grow
in semiarid climates.
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Meska
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Meska
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Meska

• Extrudate gum of the acacia tree
• Expensive hard to source
• Low viscosity, non-gelling
• Complexed with a glycoprotein -surface active

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Gums

• Meska
• One of the oldest known gums, from the bark of
  Acacia trees
• Very large complex polymer
• Up to 3.500.KDalton (varies greatly with source)
• Galactose Glucuronic acid form main building
  blocks
• Rhamnose and arabinose in minor amounts
• Very expensive compared to other gums but has
  unique properties

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Meska

• Highly branched with b-Galactose backbone
• Molecular weight 2,50,000 7,50,000
• Water soluble, fat insoluble but affinity for fat
• Low viscosity gum
• Viscosity affected by pH and salts
• Food uses
• Stabilizer for flavor emulsions
• Encapsulated flavors
• Water binding
• Inhibit sugar crystallization

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Gums

• Characteristics of Meska
• Readily dissolves in water
• Colorless and tasteless solutions of relatively
  low viscosity
• Can go up to 50 w/w
• Can manipulate solution viscosity of Meska by
  changing pH
• Low or high pH viscosity is reduced
• pH 6-8 higher viscosity is maintained

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-complex heteropolysaccharide -low viscosity
Meska
Glucuronic acid and galactose main building
blocks Rhamnose and arabinose in minor amounts
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3
1
4
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Composition 1. D-galactose, 44 2. L-arabinose,
24 3. D-glucuronic acid,14.5 4.
L-rhamnose, 13 5. 4-O-methyl-D-glucuronic
acid, 1.5.
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Meska
They contain main chains of (1 3)-linked
b-D-galactopyranosyl units having two- to
four-unit side chains consisting of (1
3)-b-D-galactopyranosyl units joined to it by (1
6)-linkages. Both the main chain and the
numerous side chains have attached
a-L-arabinofuranosyl, a -L-rhamnopyranosyl,
ß-D-glucuronopyranosyl, and 4-O-methyl-b-D-glucuro
nopyranosyl units. The two uronic acid units
occur most often as ends of chains.
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Plant exudate Different Gums
Gum karaya
Gum ghatti
Gum Tragacanth
Gum arabic
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Gums Applications of Meska

• Gum candy and pastilles (A medicated lozenge used
  to soothe the throat)
• Retards sugar crystallization
• Functions as a Coating agent and a binder
• Its functions in confections are to prevent
  sucrose crystallization and to emulsify and
  distribute fatty components.
• Ice cream and sherbets (A frozen dessert made
  primarily of fruit juice and sugar, but also
  containing milk, egg-white or gelatin)
• induces and maintains small ice crystals
• Beverages
• foam and emulsion stabilizer
• used in beverage powders (e.g. citrus drink
  mixes) to maintain and stabilize flavor
  (encapsulates flavors)
• Bakery and snack products
• Lubricant and binder
• The soft drink industry consumes about 30 of the
  gum supply as an emulsifier and stabilizer

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Applications of Meska

• It is an important ingredient in soft
  drink syrups, "hard" gummy candies such
  as gumdrops, marshmallows, chocolate candies and
  edible glitter, a very popular, modern
  cake-decorating staple.
• For artists, it is the traditional binder used
  in watercolor paint, in photography for gum
  printing, it is used as a binder
  in pyrotechnic compositions. It has
  been investigated for use in intestinal
  dialysis. 
• Pharmaceuticals and cosmetics also use the gum
  as a binder, emulsifying agent and a suspending
  or viscosity increasing agent.

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Applications of Meska

• Meska is used primarily in the food industry as
  a stabilizer.
• Meska is a key ingredient in traditional lithograp
  hy and is used in printing, paint production,
  glue, cosmetics and various industrial
  applications, including viscosity control
  in inks and in textile industries, although less
  expensive materials compete with it for many of
  these roles.

Lithography -The process of printing from a
surface on which the printing areas are not
raised but are ink-receptive (as opposed to ink
repellent)
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Uses of Meska
Powdered Meska for artists, one part Meska is
dissolved in four parts distilled water to make
a liquid suitable for adding to pigments.
A selection of gouaches  containing Meska
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Questions Meska

• Meska increases sugar crystallization True/False
• Meska functions as a foam and emulsion
• destabilizer True/false
• 3. Meska is highly branched with Rhamnose and
• arabinose backbone True/False

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Branched Ionic gums

• Xanthan

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Gums-Xanthan
Cellulose backbone

• Branched ionic gums
• Xanthan
• Produced by Xanthomonas, a microbe that lives on
  leaves of cabbage plants
• Cellulose backbone with charged trisaccharide
  branches
• Branching prevents gelation
• Very viscous due to charged branches
• Expensive ingredient

b-1,4-poly-glucose trisaccharide branches
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Xanthan
Main chain

• Backbone same as cellulose (1-4 Glucose)
• Trisaccharide side chain at 3 position of
  alternating glucose monomer units.
• Acid groups are b-D-Glucuronic acid and pyruvic
  acid on 1/2 of terminal mannose units.
• High degree of interaction between chains.
• Molecular weight about 15 million.
• Cold and hot water soluble
• High viscosity at low concentration
• Properties affected by ions
• Freeze stable

Trisaccharide side chain
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Backbone same as cellulose (1-4) Glucose)
Trisaccharide side chain
About half of the side chains are normally
pyruvylated.
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Xanthan gum

• Source Product of bacteria Xanthomonas
  campestris
• Structure cellulose-like backbone
  (b-1,4-poly-glucose) with trisaccharide branches
  (stubs) on alternate monomers on the backbone
  carrying carboxylic acid residue
• Functional Properties Water soluble, viscous,
  non-gelling. Viscosity is only slightly
  temperature dependant

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Xanthan Monomer backbone glucose (as
cellulose) side chain mannose/glucuronic
acid Bonding ?-1,4/?-1,2/?-1,3
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Xanthan
Main chain
?-1,3
Trisaccharide
?-1,2
?-1,4
?-1,4/?-1,2/?-1,3
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Xanthan
Main chain
Acetylated
Trisaccharide
Pyruvate
Main chain consists of 1,4 linked ß-glucopyranose
residues
On an average, every second glucose residue bears
in the 3-position a trisaccharide of the
structure ß-D-Manp-(1 ? 4)-ß-D-GlcpA(1 ?
2) -a-D-Manp as the side chain. The mannose bound
to the main chain is acetylated in position 6
and 50 of the terminal mannose residues occur
ketalized with pyruvate as 4,6-O- (1-carboxyethyli
dene)- D-mannopyranose (GlcpA glucuronic acid).
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Xanthan Structure-function
Low pH
Linear molecule
Random coil
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Xanthan and Carbogum Synergy
Carbogum
Carbogum
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Xanthan Properties
-only microbial gum permitted for use in
food -has cellulose backbone -is made water
soluble by the presence of short chains attached
to every second glucose -exists in solution as a
rigid rod stabilized by non covalent interaction
between the backbone and the side chains -high
viscosity -viscosity stability at elevated temp.
and over a wide pH range in the presence of
salt -synergistic interaction with guar gum or
Carbogum. ------Guar gum increases
viscosity produces thermoreversible
gel -readily disperse in hot and cold water give
high viscosity
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Gums- Xanthan-Characterstics

• Xanthan is widely used due to its unique function
• Soluble in hot and cold water
• Very high viscosity at low concentrations
• viscosity decreases when it is poured or agitated
  (shear-thinning)
• Viscosity is independent of temperature (10-95C)
  and pH (2-13)
• High freeze-thaw stability
• Compatible with most food grade salts

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Gums- Xanthan-Uses

• Xanthan is widely used due to unique function
• Ideal for emulsions ?excellent in fat-free
  dressings due to viscosity, and smooth mouth feel
• Excellent food stabilizer
• Good for thermally processed foods
• Expensive

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Questions Xanthan

• Branching augments gelation True/false
• Very viscous due to uncharged branches True/False

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Questions Xanthan

• Branching augments gelation False
• Very viscous due to uncharged branches False

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Questions General
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Questions

• Glucose is stored in the form of starch in
  humans- True/False
• Glucose is stored in the form of Glycogen in
  Plants- True/False
• Structural linearity reduces viscosity-
  True/False

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Questions

• Esterification is reduced in unripened fruits
  True/False
• Esterification is increased in ripened fruits
  True/False
• Decreased hydration increases viscosity
  True/False
• Increased hydration increases viscosity
  True/False

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Questions

• Esterification is reduced in unripened fruits
  False
• Esterification is increased in ripened fruits
  False
• Decreased hydration increases viscosity False
• Increased hydration increases viscosity
• True

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Questions

• Linear structure increases Viscosity True/False
• Branched structure increases Viscosity True/False
• The reason for Glucose to be stored in the form
  of Glycogen in humans is
• Name two ionic Non-ionic gums
• Alginate is a monomer of
• Carrageenan is a monomer of

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Answers

• Linear structure increases viscosity
• True
• Branched structure increases viscosity
• False

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Concepts

• Linear StructureMore the linearity-- More the
  viscosity lower the gel stability
• Branched structureMore the branched
  structurelower the viscosity Increased gel
  stability
• Esterification Increased Esterification Harder
  the texture (unripened fruits)
• Decreased Esterification Softer the texture
  (ripened fruits)

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Concepts

• Gelation Linear structure increases gelation
  Branchingdecreases gelation
• Hydration Increased hydration increases
  viscosityincreases stabilizing effect
• Decreased hydration decreases viscositydecreases
  stabilizing effect
• pH Decreased pH (acidic)-- increases
  aggregation---increases precipitation
• Increased pH (basic)-- decreases
  aggregationincreases solubility

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Questions

• The viscosity of carrageen is quite stable over a
  wide range of pH values..
• Uses of aliginate in food industry.
• Uses of pectin in food industry.
• The most important seaweed polysaccharide used in
  food industry is

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Functions of Gums in Food Systems

• Water binding Viscosity building
• Gelation Suspension
• Emulsions stabilization Foam stabilization
• Encapsulation Binder
• Fat Replacement

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Functions of gums in foods are related to
interactions with other food components

• Gums interact with
• Component   Affects     
• Water   All properties
• Proteins   Emulsions, foams,gels
• Lipids   Emulsions
• Ions   Gels
• Particle surfaces Stabilization

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Hydration of Gums

• All functions of gums require that the gums be
  hydrated.
• Failure to hydrate gums properly is the leading
  cause of problems in foods containing gums.
• Competition for water with other water loving
  components affects properties

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Hydration of Gums

• Linear, uncharged polysaccharide molecules are
  held tightly together by hydrogen bonds.
  Substantial inputs of energy are required in
  order to make these function properly.
• Amylose crystalline structure requires
  substantial input of heat before gelatinization
  occurs. (No branches)
• Carbogum (has some branches) requires heating to
  fully develop viscosity
• Guar Gum ( 2x as many branches) swells in cold
  water
• Introduction of branches and/or charges into the
  chain limit the amount of hydrogen bonding
  that can take place between polysaccharide
  molecules and thus increase the interaction with
  water and make gums more
• easy to hydrate.
• Increased no. of Branches increases the
  interaction with water.

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Structure and Function

• Carageenan - charge of sulfates
• Xanthan - Charge on carboxyl branches
• Guar Gum- increased branches

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Interaction of Gums with Proteins

• Gums May affect protein stability by
• Electrostatic interaction - negatively charged
  hydrocolloids may interact with positively
  charged groups on proteins.
• Interactions depend on
• pH
• pK of ionizable group
• Ionic strength
• Ratio of protein to gum
• Interference with calcium binding -
• -Protect calcium sensitive proteins e.g..
  carageenan
• Competing for water - hydrocolloids may cause
  proteins to precipitate by limiting the water
  available to hydrate the protein.

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Gums and Lipids

• Only a few gums show affinity for lipid.
• Gum Arabic, hydroxypropyl cellulose, and
  propylene glycol alginate have a little
  affinity for lipid.
• Stabilization of emulsions, foams, etc. is
  dependent upon
• interactions with the protein on the surface and
• increases in viscosity of the continuous phase.
• Gums which are complexed with other food
  components may not be able to exert their primary
  functions.

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Viscosity of Gums

• All are highly viscous except Gum Arabic
• Viscosity is dependent upon hydration of the
  polysaccharide.
• Larger polymers generally give higher viscosity.
  Interactions with other polymers may dramatically
  affect viscosity.

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Stability of Gums

• Most gums are resistant to microbial degradation
• Pectin is a notable exception
• Commercial stabilizers almost always
  are'standardized" with sugar and thus are
  readily fermented.
• Depolymerization upon heating is common.

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Classification of gums used in food products

• Non-ionic seed polysaccharides
• Guar, Carobgum
• Anionic (negatively charged) exudate
  polysaccharides
• Gum Arabic/Meska

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Classification of gums used in food products

• Anionic seaweed polysaccharides
• Agar, Algin, Carrageenan
• Microbial gums -
• Xanthan, Gellan
• Others -
• Celluloses, Pectins

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Classification of Polysaccharides Based on
Structure

• Neutral i.e. Not charged
• Starch
• Cellulose
• Carobgum
• Guar Gum
• What are the implications of not being charged?

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Classification of Polysaccharides Based on
Structure

• Carboxylated i.e. Having a COOH
• Algin
• Carboxymethylcellulose
• Pectin
• Xanthan
• What are the implications of having COOH groups?

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Classification of Polysaccharides Based on
Structure

• Sulfated i.e. SO3-
• Carageenan
• What are the implications of having a negative
  charge?

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Thanks