1 Pectin X is either H or CH 3 Subject to enzyme attacks Found in virtually all land-based plant as a structural material Commercial pectin extracted from citrus peel, apple pomace, sugar beet, or sunflower heads A linear chain of galacturonic acid units with molecular weight about 110,000-150,000 In native pectin one free galacturonic acid units is followed by 5 methyl esters of galacturonic acid, with degree of esterification (DE) of 83.3% DE can be controlled during extraction processing, to obtain low ester (low methoxyl) pectin (DE<50%) or high ester (high methoxyl) pectin (DE>50) Low ester pectins gel with calcium, and high ester pectins gel with high sugar solids at low ph Figure from Principles of Enzymology for the Food Sciences
2 Hypothetical Pectin Structure Handbook of hydrocolloids
3 Pectin Gelation properties of pectins Gelation of high methoxyl pectins The presence of sugars is required At a sufficiently low ph Reduced ph leads to increased gel strength and setting temperature Nature of sugars affects pectin performance (e.g. replacement of sugar by glucose syrup leads to increased setting temperature and ph for gelation, but reduced maximum gel strength) Increased sugar amount leads to increase of setting temperature and optimum ph Gelation of low methoxyl pectins Governed mainly by interaction between pectin and calcium ions Thus the presence of sequestrant has effects (citrate, di-/poly-phosphate) on gelation, and can be used to produce workable gel system Reactivity increases with decreasing degree of esterification Increased solubles and reduced ph favors gelation
4 Pectin Gelation properties of pectins 80 70 Classification Rapid set Slow set Uses Acid milk products, jam Jellies, bakery, confectionery 60 High methoxyl 50 40 30 Low methoxyl Low Medium High Calcium reactivity Reduced sugar products Low sugar or low acid products 20 10 Pectate
5 Pectic Enzymes Ester bond Hydrolyzed Pectin methylesterase Hydrolyzes the methyl ester bond to produce pectic acid and methanol Converts high ester pectin to low ester pectin Figure from Principles of Enzymology for the Food Sciences
6 Pectic Enzymes Polygalacturonase (plants and microorganism) Hydrolyzes the -1,4-glycosidc bond between anhydrogalacturonic acid units Leads to significant decrease of texture (e.g. tomatoes) Figure from Principles of Enzymology for the Food Sciences
7 Pectic Enzymes Pectate lyases (microorganism) Split (without water) the glycosidic bonds by -elimination Leads to significant decrease of texture Figure from Principles of Enzymology for the Food Sciences
8 Pome Fruit Processing Pectinase Apples and pears Maceration enzymes: pectinases & cellulases Mash treatment Maceration Pressing Decanting Pomace Juice Solids Extraction Extraction Maceration Pressing/decanting Extract Depectinization Starch degradation Apple/pear juice concentrate Extract Juice treatment: Pectinases Arabinanases Amylases Proteases 8
9 Gum Arabic http://kantilalbrothers.tradein dia.com/
10 Gum Arabic A gummy exudate obtained from Acacia trees in Africa, primarily Sudan, also called Acacia gum Only gum from A. senegal and A. seyal is approved for food Hand-sorted gum is usually dissolved, clarified, and spray-dried Annual production around 60,000 MT Highly branched polysaccharide constructed from both neutral monomers and uronic acids Covalently attached with proteinaceous fractions, rendering its excellent function as emulsifier Molecular weight about 250,000 Highly soluble, low viscosity even at 40% concentration Solution showing Newtonian behavior (constant viscosity at different shear rate)
11 Gum Arabic Putative structure of gum arabic: A: arabinosyl R1: rhamnose-glucuronic acid R2: galactose-1,3-arabinose R3: arabinose-1,3-arabinose-1,3-arabinose Filled circle: β-1,3 linked D-galactose Open circle:1,6 linked galactose Handbook of hydrocolloids
12 Gum Arabic Molecular weight and size for A. sengal gum obtained from trees of various ages at different location (adopted from Food Polysaccharides and Their Applications, 2 nd ed.) Gum type (region year) E 5 E 10 E 15 E 20 W 5 W 10 W 15 W 20 Mw (Molecular weight), 10 5 3.2 2.9 7.9 4.6 3.3 4.4 4.7 2.0 Rg (Radius of gyration), nm 8.2 13.7 14.1 13.5 13.1 15.8 16.4 7.1 Rh (hydrodynamic radius), nm 12 14 19 15 12 17 21 10 Ρ (molecular density, Mw/Rg 3 580 112 281 186 146 111 106 558
13 Gum Arabic Carbohydrate blocks Polypeptide chain (~400 amino acid residues
14 Gum Arabic Functional properties Rheological behavior Extremely high solubility, coupled with low viscosity Attributed to the spheroidal molecular shape and very high branch density Uronic acid groups leading to polyelectrolyte character Viscosity strongly affected by ph and presence of electrolyte, passing through a broad maximum at ph4.5-7 Addition of electrolytes resulting in viscosity decrease Viscosity of solution decreasing on ageing due to microbial degradation
15 Gum Arabic Functional properties Emulsification properties Widely used as an emulsifier to stabilize flavor oil emulsion for the soft drink industry Treatment with protease results in a loss of emulsification capability Hydrophilic carbohydrate blocks Hydrophobic polypeptide chain
16 Gum Arabic Functional properties Encapsulation Encapsulation of volatile compounds (fragrance/flavor) is one of the primary functions in food processing, sometimes used with maltodextrin to reduce cost Coacervation with gelatin (pi 8) to form individual spheres containing oil droplets, due to electrostatic interaction between positively charged protein and uronate anions of gum arabic Gum/gelatin ratio, ph, salt concentration all affect coacervation
17 Gum Arabic Food applications Verbeken et al., 2003, Appl Microbiol Biotechnol (2003) 63:10 21
18 Gum Arabic Ingredients of Slim-Fast Optima Ready To Drink Shake http://www.amazon.com/slim-fast-3-2-1-creamy-chocolate-11-ounce/dp/b000ydcaag Fat Free Milk, Water, Sugar, Cocoa (Processed with Alkali), Canola Oil, Fructose, Gum Arabic, Calcium Caseinate, Cellulose Gel, Potassium Phosphate, Soybean Lecithin, Cellulose Gum, Mono and Diglycerides, Carrageenan, Maltodextrin, Artificial Flavor, Sucralose (a Nonnutritive Sweetener), Dextrose, Citric Acid and Sodium Citrate. Vitamins and Minerals: Magnesium Phosphate, Calcium Phosphate, Sodium Ascorbate, Vitamin E Acetate, Zinc Gluconate, Ferric Orthophosphate, Niacinamide, Calcium Pantothenate, Manganese Sulfate, Vitamin A Palmitate, Pyridoxine Hydrochloride, Riboflavin, Thiamin Mononitrate, Folic Acid, Chromium Chloride, Biotin, Sodium Molybdate, Potassium Iodide, Phylloquinone (Vitamin K1), Sodium Selenite, Cyanocobalamin (Vitamin B12) and Cholecalciferol (Vitamin D3). Sweetened with Nutritive Sweeteners and a Nonnutritive Sweetener.