Lecture XI Polysaccharides III Classification, Structure, Function, Hydration/Dispersion Lecture #11 - Polysaccharides III - Classifi-cation, Structure, Function, Hydration/Dis-persion - general overview (more specifics when get into individual gums) NOTE: Info in these first few lectures on PSs very impt! Foundational! Principles you need to understand. Specifics on individual gums in future lectures.

Classification of PSs By Source

Classification of PSs Source Structure Composition Properties Other

Classification of PSs 4346

Structure/Function of PSs Minor changes = Major effects Amylose vs Cellulose, e.g. Structure determines function Similar to proteins

O CH2OH OH n Amylose O CH2OH OH n Cellulose

Primary Secondary Quatinary Tertiary Kelco CR Sem 4345

Major Hexose Sugars (related to Glucose) 6 CH2OH 5 O 1 4 OH OH OH 3 2 OH- to here = Mannose OH- to here = Galactose OH a-D-GLUCOSE (a-D-Glucopyranose)

Distribution of CHO Units OH COOH b-D-Mannuronic Acid a-L-Guluronic Acid Polymer Structure: M G Mannuronic Block Guluronic Block Mixed Block

Structure/Function of PSs Importance of substituent Kind of sugar Branches Charged groups

Structure/Function of PSs Importance of glycosidic linkage Polysaccharide Confirmations Type A E.g. b-1,4-glucan a-1,4-galactan b-1,4-mannan Type B E.g. a-1,4-glucan b-1,4-galactan a-1,4-mannan

Structure/Function of PSs Glucose-based Polymers Amylose & Amylopectin Glycogen Cellulosics Chitin & Chitosan Xanthan Gum Gellan Gum

Segment of Linear Chain Precipitate Dilute Solution Segment of Linear Chain Gel Concentrated Solution

O CH2OH OH n Amylose O CH2OH OH n Cellulose

Cellulose products used in foods a Cellulose Chemical Derivatization Chemical Depolymerization Wet Mechanical Disintegration Soluble Cellulose Derivative Drying Dispersing Agent + Water Powdered Avicel (PH/FD Grades Colloidal Avicel Hydrocolloid Solution + Water Aqueous Colloidal (RC/CL Grades)

Microcrystalline Cellulose Polymers in solid ("dry") state Crystalline (ordered) vs Amorphous (disordered) Bundles of Microcrystals Paracrystalline (amorphous) area Cellulose microfibril

Cellulose Derivatives CH2OR OR 6 5 4 3 2 1 b-D- anhydroglucose unit R = -CH2COONa = NaCMC R = -CH3 = MC R = -CH2(CHOH)CH3 = HPC R = -CH2(CHOH)CH3 and -CH3 = HPMC R = -CH2CH2OH = HEC

XANTHAN GUM STRUCTURE Primary Aspect M = Na+, K+ or Ca++ n CH2OH CH2OAc OH COO-M+ OCH2 C CH3 n CH2OH XANTHAN GUM STRUCTURE Primary Aspect M = Na+, K+ or Ca++

From Sphingomonas elodea organism Gellan Gum Repeat Unit CH2OR1 COO- M+ CH2OH O CH3 O O OH O OH HO OR2 OH OH OH OH n R1 = CH3C=O (acetate) - for “Native”, or H- for deacylated Gellan Gum R2 = HOCH2CH(OH)C=O (glycerate) - for “Native”, or H- for deacylated Gellan Gum From Sphingomonas elodea organism

Structure/Function of PSs Mannose-based Polymers Alginates Locust Bean Gum (LBG) Tara Guar

Mannose-based Polymers LBG & Guar

Algin Basic Structure a-L-Guluronic Acid Polymer Structure: M G OH COOH b-D-Mannuronic Acid a-L-Guluronic Acid Polymer Structure: M G Mannuronic Block Guluronic Block Mixed Block

Propylene Glycol Alginate (PGA) Structure OH COOH COOCH2CHCH3

Structure/Function of PSs Galactose-based Polymers Pectins Agar Carrageenans

Galactose-based Polymers High Methoxyl Pectin (H-bonding at pH 3) = n C COCH3 OH C=O H COOCH3 D-galacturonic acid

Repeating Unit of Agaran CH2 OH CH2OH

Repeating Unit of k-Carrageenan CH2 O OH n CH2OH -O3SO

Function of Hydrocolloids Hydration & Dispersion Definitions Dispersion - The separation of individual dry gum particles added to a liquid. Hydration - The disappearance of gum particles as a result of water surrounding each individual polymer molecule, causing it to swell and then slough away from the starting particle, forming a uniform “solution” (colloidal sol).

Function of Hydrocolloids Hydration & Dispersion Polymers in solid ("dry") state Crystalline (ordered) vs Amorphous (disordered) Bundles of Microcrystals Paracrystalline (amorphous) area Cellulose microfibril

Function of Hydrocolloids Hydration & Dispersion = n C COCH3 OH C=O H COOCH3 HO d- d+

Function of Hydrocolloids Hydration & Dispersion

Function of Hydrocolloids Hydration & Dispersion Comparative hydration effect of linear and branched polymers of equal molecular weights

Stages of Particle Hydration Dispersion Swollen Particles, Unhydrated Center Wet but unhydrated particles Full Hydration Swelling “Solution” Intimate Mixing with Solvent

Function of Hydrocolloids Hydration & Dispersion Polymer Solubility Characteristics I

Function of Hydrocolloids Hydration & Dispersion Polymer Solubility Characteristics II

Function of Hydrocolloids Solution Properties I Comparative hydration effect of linear and branched polymers of equal molecular weights

Function of Hydrocolloids Solution Properties II Comparative hydration effect of linear and branched polymers of equal molecular weights

Hydration Rate Comparison vs Hydration Medium 100 90 80 70 80 mesh XG 60 Torque (% of Max) 50 80 mesh XG w/ 0.5% NaCl 40 80 mesh XG w/ 0.5% NaCl + 12.5% Vinegar 30 20 10 1 2 3 4 5 6 Time (minutes)

Function of Hydrocolloids Solution Properties III Based on structure of polymer Effects of various solutes Salts, alcohols, etc Other gums General guidelines for optimum hydration

Dispersion & Hydration Rate Hydration Rate/ 4 Factors 1. Dispersion 2. Particle Size 3. Mixer Speed/Shear 4. Hydration Medium - “Solvent”

Hydration Rate Comparison as a Function of Particle Size 100 90 80 70 60 200 Mesh XG 50 80 Mesh XG 40 30 16 Mesh XG 20 10 1 2 3 4 5 6 7 8 9 Time (minutes)

“High” shear mixer Using careful addition, the dry gum is added directly to a vortex slowly enough to get good separation of the particles prior to wetting and swelling.

Dispersion - Mechanical High Shear Mixer II Uses High agitation rate to mechanic-ally separate par-ticles to allow uni-form wetting by the hydration medium. Examples: Blender, Breddo Liquifier, Silverson, Arde Barinco Reversible Homogenizer

Dispersion - Mechanical Eductor Funnel Uses vacuum to aspirate the gum particles into the hydration medium.

Dry Blending - Solid Dispersant Sugar Partially hydrated particles Fully hydrated particles Using 5 to 10 parts of a diluent such as sugar, starch or spices, the gum is blended prior to incorporation into the liquid. Salt is generally not recommended. Good “Solution”

Dispersion - Liquid Slurry Pre-mix with non-solvents Water miscible liquids alcohols glycols liquid sugars nonmiscible liquids vegetable oil mineral oil Keep mixed to avoid settling

Preservation of Gum Solutions Most gum solutions need preservation Food product & pH determine “preservative” Neutral systems Acidic systems (pH < 5)

Colloids/Colloidal State Viscosity Brookfield RVF Viscometer (courtesy of Brookfield)

Hydrocolloid Pricing: Typical $ Cost/lb 2006 2012 Guar 0.60-1.10 6.00 – 6.80↑ LBG 3.70-7.00 no change* Konjak 5.50-8.50 no change Na+ alginate 6.50-13.00 6.50-8.00↓ K+ alginate 12.00-13.35 8.00-12.00↓ PGA 8.50-10.70 Agar 8.00-9.50 8.00-11.00↑ Arabic 1.20-2.40 1.20-5.50↑ Xanthan 2.50-6.50 2.50-4.00↓ Pectin 3.00-5.00 3.00-6.00↑ CMC 1.50-3.50 2.00-4.00↑ MC/HPMC 3.00-8.00 Carrageenan 2.50-12.00 Tragacanth 15.00-30.00 no change** * can reach $12.00-$17.00/lb in times of shortage ** depends on availability (Source = John Keller)