FOOD CHEMISTRYFOOD CHEMISTRYGumsGums
BYDR BOOMINATHAN Ph.D.
M.Sc.,(Med. Bio, JIPMER), M.Sc.,(FGSWI, Israel), Ph.D (NUS, SINGAPORE), PDF (USA)PONDICHERRY UNIVERSITY
Sixth lecture17/August/2012
Source: Collected from different sources on the internet and modified by Dr Boominathan Ph.DRef. Food chemistry by Fennema.
GoalsGoals
Structural arrangements of different Gums::MeskaXanthanCompositionPhysico-chemical properties of Meska & XanthanApplications of Gums in food industry
Gum arabic/acacia gumGum arabic/acacia gum//meskameska
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.
MeskaMeska
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MeskaMeska
MeskaMeska
Extrudate gum of the acacia treeExpensive – hard to sourceLow viscosity, non-gellingComplexed with a glycoprotein -surface
active
GumsGumsMeska
– 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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MeskaMeska
Highly branched with -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
GumsGums Characteristics of Meska
– Readily dissolves in waterColorless and tasteless solutions of relatively low viscosityCan go up to 50% w/w
– Can manipulate solution viscosity of Meska by changing pHLow or high pH = viscosity is reduced pH 6-8 = higher viscosity is maintained
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Meska-complex heteropolysaccharide-low viscosity
Glucuronic acid and galactose main building blocksRhamnose and arabinose in minor amounts
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%.
1
2
3
4
5
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 α-L-arabinofuranosyl, α -L-rhamnopyranosyl, β-D-glucuronopyranosyl,and 4-O-methyl-b-D-glucuronopyranosyl units.The two uronic acid units occur most often as ends of chains.
Plant exudate : Different Gums
Gum karaya
Gum ghatti
Gum Tragacanth
Gum arabic
Gums: Gums: Applications of MeskaApplications 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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* 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.
Applications of MeskaApplications of Meska
Meska is used primarily in the food industry as a stabilizer.
Meska is a key ingredient in traditional lithography 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.
Applications of MeskaApplications of Meska
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)
Uses of MeskaUses of Meska
A selection of gouaches containing Meska
Powdered Meska for artists, one part Meska is dissolved in four parts distilled water to make a liquid suitable for adding to pigments.
Questions: MeskaQuestions: Meska
1. Meska increases sugar crystallization True/False2. Meska functions as a foam and emulsion destabilizer True/false3. Meska is highly branched with Rhamnose and arabinose backbone True/False
Branched Ionic gums:Branched Ionic gums:
Xanthan
Gums-XanthanGums-Xanthan
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
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-1,4-poly-glucose trisaccharide branches
Cellulose backbone
XanthanXanthan 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
Main chain
Trisaccharide side chain
About half of the side chains are normally pyruvylated.
Backbone same as cellulose (1-4) Glucose)
Trisaccharide side chain
Xanthan gumXanthan gum
Source: Product of bacteria Xanthomonas campestris
Structure: cellulose-like backbone (-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
XanthanMonomer: backbone glucose (as cellulose)
side chain mannose/glucuronic acidBonding: -1,4/-1,2/-1,3
Xanthan
-1,4
-1,2
-1,3
-1,4/-1,2/-1,3
Main chain
Trisaccharide
Xanthan
Main chain consists of 1,4 linked β-glucopyranose residuesOn an average, every second glucose residue bears in the 3-positiona trisaccharide of the structure β-D-Manp-(1 → 4)-β-D-GlcpA(1 → 2)-α-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-carboxyethylidene)- D-mannopyranose (GlcpA: glucuronic acid).
Main chain
Trisaccharide AcetylatedPyruvate
--
--
--
--
Low pH
Linear molecule
Random coil
Xanthan: Structure-functionXanthan: Structure-function
Xanthan and Carbogum SynergyXanthan and Carbogum Synergy
Carbogum
Carbogum
-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
Xanthan: Properties
Gums- Xanthan-CharactersticsGums- Xanthan-Characterstics
Xanthan is widely used due to its unique function1. Soluble in hot and cold water2. Very high viscosity at low concentrations3. viscosity decreases when it is poured or agitated (shear-
thinning)4. Viscosity is independent of temperature (10-95°C) and pH
(2-13)5. High freeze-thaw stability6. Compatible with most food grade salts
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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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Gums- Xanthan-Uses
Questions: XanthanQuestions: Xanthan
Branching augments gelation True/false
Very viscous due to uncharged branches True/False
Questions: XanthanQuestions: Xanthan
Branching augments gelation False
Very viscous due to uncharged branches False
Questions: Questions:
GeneralGeneral
QuestionsQuestions
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
QuestionsQuestions
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
QuestionsQuestions
Esterification is reduced in unripened fruits False
Esterification is increased in ripened fruits False
Decreased hydration increases viscosity FalseIncreased hydration increases viscosity
True
QuestionsQuestionsLinear structure increases Viscosity True/FalseBranched structure increases Viscosity
True/FalseThe reason for Glucose to be stored in the form
of Glycogen in humans isName two ionic & Non-ionic gumsAlginate is a monomer of Carrageenan is a monomer of
AnswersAnswers
Linear structure increases viscosity
TrueBranched structure increases viscosity
False
ConceptsConcepts
Linear Structure—More the linearity-- More the viscosity– lower the gel stability
Branched structure—More the branched structure—lower the viscosity– Increased gel stability
Esterification: Increased Esterification– Harder the texture (unripened fruits)
Decreased Esterification– Softer the texture (ripened fruits)
ConceptsConcepts
Gelation: Linear structure– increases gelation; & Branching—decreases gelation
Hydration: Increased hydration– increases viscosity—increases stabilizing effect
Decreased hydration– decreases viscosity—decreases stabilizing effect
pH: Decreased pH (acidic)-- increases aggregation---increases precipitation
Increased pH (basic)-- decreases aggregation—increases solubility
QuestionsQuestions
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
??
Functions of Functions of GumsGums in in Food SystemsFood Systems
Water binding Viscosity building
Gelation Suspension
Emulsions stabilization Foam stabilization
Encapsulation Binder
Fat Replacement
Functions of gums in foods are related Functions of gums in foods are related to interactions with other food to interactions with other food
componentscomponents
Gums interact with:
Component Affects Water All properties Proteins Emulsions, foams,gels Lipids Emulsions Ions Gels Particle surfaces Stabilization
Hydration of GumsHydration 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
Hydration of GumsHydration 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.
Structure and FunctionStructure and Function
Carageenan - charge of sulfates
Xanthan - Charge on carboxyl + branches
Guar Gum- increased branches
Interaction of Gums with ProteinsInteraction 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.
Gums and LipidsGums 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.
Viscosity of GumsViscosity 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.
Stability of GumsStability 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.
Classification of gums used in Classification of gums used in food products:food products:
Non-ionic seed polysaccharides —
– Guar, Carobgum
Anionic (negatively charged) exudate polysaccharides —
– Gum Arabic/Meska
Classification of gums used in Classification of gums used in food productsfood products::
Anionic seaweed polysaccharides —
– Agar, Algin, Carrageenan
Microbial gums -
– Xanthan, Gellan
Others -
– Celluloses, Pectins
Classification of Polysaccharides Classification of Polysaccharides Based on StructureBased on Structure
Neutral i.e. Not charged– Starch– Cellulose– Carobgum– Guar Gum
What are the implications of not being charged?
Classification of Polysaccharides Classification of Polysaccharides Based on StructureBased on Structure
Carboxylated i.e. Having a COOH– Algin– Carboxymethylcellulose– Pectin– Xanthan
What are the implications of having COOH groups?
Classification of Polysaccharides Classification of Polysaccharides Based on StructureBased on Structure
Sulfated i.e. SO3-
– Carageenan
What are the implications of having a negative charge?
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