FOOD CHEMISTRY Gums

1. 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 BoominathanPh.D Ref. Food chemistry by Fennema .

2. Goals • Structural arrangements of different Gums:: • Meska • Xanthan • Composition • Physico-chemical properties of Meska & Xanthan • Applications of Gums in food industry

3. Gum arabic/acacia gum/meska When the bark of some trees and shrubs is injured, the plants exudeasticky 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.

4. Meska

5. Meska

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

7. 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

8. 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

9. 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

10. -complex heteropolysaccharide -low viscosity Meska • Glucuronic acid and galactose main building blocks • Rhamnose and arabinose in minor amounts 5 3 1 4 2 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%.

11. 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.

13. Plant exudate : Different Gums Gum karaya Gum ghatti Gum Tragacanth Gum arabic

14. 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

15. Applications of Meska * It is an important ingredient in soft drinksyrups, "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 watercolorpaint, 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.

16. Applications 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) 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 viscositycontrol in inks and in textile industries, although less expensive materials compete with it for many of these roles.

17. 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

18. 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

19. Branched Ionic gums: Xanthan

20. Cellulose backbone Gums-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 b-1,4-poly-glucosetrisaccharide branches

21. 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

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

23. 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

24. Xanthan Monomer: backbone glucose (as cellulose) side chain mannose/glucuronic acid Bonding: -1,4/-1,2/-1,3

25. Xanthan Main chain -1,3 Trisaccharide -1,2 -1,4 -1,4/-1,2/-1,3

26. Xanthan Main chain Acetylated Trisaccharide Pyruvate Main chain consists of 1,4 linked β-glucopyranose residues On an average, every second glucose residue bears in the 3-position a 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).

27. - - - - - - - - Xanthan: Structure-function Low pH Linear molecule Random coil

28. Xanthan and Carbogum Synergy Carbogum Carbogum

29. 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

30. 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 (10-95°C) and pH (2-13) • High freeze-thaw stability • Compatible with most food grade salts

31. 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

38. Questions: Xanthan Branching augments gelation True/false Very viscous due to uncharged branches True/False

39. Questions: Xanthan Branching augments gelation False Very viscous due to uncharged branches False

40. Questions: General

41. 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

42. 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

43. 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

44. 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

45. Answers Linear structure increases viscosity True Branched structure increases viscosity False

46. Concepts 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)

47. Concepts 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

48. 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

49. ?

50. Functions of Gums in Food Systems Water bindingViscosity building Gelation Suspension Emulsions stabilization Foam stabilization EncapsulationBinder Fat Replacement