Types of Carbohydrates n Simple sugars n Smallest sugar molecules n Sugar alcohols n Sugar acids n Sugar amines n Complex sugars n polysaccharides –Polymers of simple sugars n fibre

Simple Sugars n Monosaccharides n Smallest sugars n Can be absorbed without digestion n Sweet tasting n Can combine with others to make larger molecules: n Disaccharides n Polysaccharides

Hexoses n Galactose HexosesHexoses C 6 H 12 O 6C 6 H 12 O 6 Glucose Galactose Fructose

Monosaccharides n Pentosans n DNA & RNA C 5 H 10 O 5 Polymerise to form PentosesPentoses

Simple SugarsSimple Sugars n Disaccharides Formed by joining two. monosaccharidesFormed by joining two. monosaccharides: Sucrose Lactose Maltose MaltoseMaltose from two Glucosefrom two Glucose LactoseLactose From glucose & galactoseFrom glucose & galactose SucroseSucrose From glucose & fructoseFrom glucose & fructose

Use of Simple Sugars n Sweeteners –good tasting n Consistency –sauces, glazes, syrups n Preservatives –Cordials, glazed fruit, dried fruit –jams, sweetened condensed milk

Problems with Simple Sugars n Absorbed too quickly form digestive tract. n Causes the pancreas to produce excess insulin n Tissues become insensitive to insulin > Type II diabetes

More Problems with Simple Sugars n Encourages tooth decay bacteria n Empty kilojoules l Not enough vitamins & minerals as needed for catabolism for catabolism l Takes Vitamins away from growth & repair

Solutions to sugar problem n Use artificial sweeteners n Aspartame (nutrasweet), Saccharin, Sucralose Some are banned in USASome are banned in USA Don’t have consistencyDon’t have consistency n Use Polyols Not absorbedNot absorbed n Eat more fibre Slows rate of absorptionSlows rate of absorption

Sweetness Of Sugars n The relative sweetness power (RSP) for –five simple sugars in 5% solutions. Sugar Lactose Galactose Glucose Sucrose Fructose RSP:

Sugar Acids n Found as units of pectin (polymer) n Glucuronic Acid n Glucuronic Acid Methyl Ester Ester

Sugar Amines n Found as units of Polymers: chitin and in bacterial cell walls n Glucosamine n N-acyl glucosamine

Polyols (or "sugar alcohols") Polyols (or "sugar alcohols")Polyols n Sorbitol n Manitol n Iditol

Properties of Polyols Properties of Polyols n Made from simple sugars –Functional properties – –Vary in their sweetness and kilojoule density, but are non-calarigenic because they are not absorbed SorbitolSorbitol 60% 10.0 IsomaltIsomalt 55% 8.4 LactitolLactitol 40% 8.4 MannitolMannitol65% 6.7 Polyol % Sweetness kj/g

Complex Carbohydrates Digestible Complex CHO Indigestible Fibre  Links  Links

n Amylose --> straight chain n Amylopectin --> Branched chain

Digestible Complex Carbohydrates –All digested slower than simple sugars n Starch - in plants –Amylose ( Straight chain) –Amylopectin ( Branched chain) n Dextrin –Smaller fragments of starch n Glycogen - in meats –branched chain

Indigestible Polysaccharides (Fibre) n Crude Fibre and Dietary Fibre : n Insoluble and soluble fibre n Crude fibre (Insoluble) –Non-starch polysaccharide (NSP): n Lignin n Cellulose n Chitin

Dietary Fibre n Soluble Fibre : Pectin Undigested starch Retrograded amylose   - Glucans Inulin

Inulin n Polymer of Fructose n found in: n chicory, artichoke, dahlia, onion and garlic

Fibre Polysaccharides n Pectins –a dietary fibre n Chitin –a crude fibre All have  - links

Dietary Need For Fibre How much do we need? n Digestible Carbohydrates Ô No daily allowance has been recommended Ô But we need a lot of it n Fibre è 20 to 30 gams per day è Most Australians eat less than half this.

Why do we need Digestible Carbohydrates? n Energy –Brain, Red blood and Kidney Cells use only Glucose for energy n Anaplerosis –Citric Acid Cycle intermediates are made only from sugar n NADPH –Made via Direct Oxidative pathway from glucose is needed for synthesis Conversion to Pentoses Conversion to Pentoses –Needed for DNA and RNA

Carbohydrate Catabolism