3/2/14 Carbohydrates Part One The most abundant organic molecules Initial source of ALL FOOD ·Provide ·Energy(~4CaVg) ·Carbon ·Fiber Significant contribution to the properties of foods Where is Sugar in Food? Contributions to Food Properties -Sweetness .Precursors of aroma compounds .Precursors of colored compounds Added sugar .Provide texture r found in .Cellulose Candy.ch .Starch Soft drinks .Pectin ts.snacks Build viscosity at low concentration .Starch com syrup .Gums .Cellulose fragments
3/2/14& 1& Carbohydrates Part One Carbohydrates • The most abundant organic molecules • Initial source of ALL FOOD • Provide • Energy (~4 Cal/g) • Carbon • Fiber • Significant contribution to the properties of foods . Where is Sugar in Food? Naturally found in: Fruits, vegetables, grains, dairy products Added sugar found in: Candy, chocolate Desserts, baked goods, ice cream Soft drinks Condiments, snacks On labels as sugar, sucrose, invert sugar, corn syrup Contributions to Food Properties •Sweetness •Precursors of aroma compounds •Precursors of colored compounds •Provide texture •Cellulose •Starch •Pectin •Build viscosity at low concentration •Starch •Gums •Cellulose fragments
3/2/14 ClassifieationsacuMupa2 Polysaccharides .Monosaccharides -Polysaccharides .Polyhydroxy aldehydes .Starch .Polyhydroxy ketones .Glucose polymer,a-1,4-linkages,1,6 branches Oligosaccharides -Cellulose .Disaccharides .Glucose polymer,B-1,4-linkages .Pectin .Sucrose,Maltose,Lactose "Polygalacturonic acid(methyl esters) .Trisaccharides .Gums ·Raffinose .Carrageenans .Tetrasaccharides -Alginates .Stachyose -Locust bean gum etc. Nutritional Availability Trioses the simplest sugars Readas bed and metabolized H、 =0 H C H-C-OH HO-C-H HC (HCOH) CH2OH CHOH Glycoaldehyde CH2OH Enantiomers- C-0 CH2OH 1,3-0 2
3/2/14& 2& Classifications •Monosaccharides •Polyhydroxy aldehydes •Polyhydroxy ketones •Oligosaccharides •Disaccharides •Sucrose, Maltose, Lactose •Trisaccharides •Raffinose •Tetrasaccharides •Stachyose http://www.chem.qmw.ac.uk/iupac/2carb/ Polysaccharides •Polysaccharides •Starch •Glucose polymer, α-1,4-linkages, 1,6 branches •Cellulose •Glucose polymer, β-1,4-linkages •Pectin •Polygalacturonic acid (methyl esters) •Gums •Carrageenans •Alginates •Locust bean gum •etc. Nutritional Availability •Readily absorbed and metabolized •Glucose •Fructose •(Galactose) •Not Absorbed •Polysaccharides (fiber) •Disaccharides (some diffusion) •Some are hydrolyzed in the intestinal mucosa •Prebiotic oligosaccharides (food for Probiotic bacteria) •Fermentable oligosaccharides can lead to flatulence (gas-producing anaerobes) Trioses the simplest sugars C H C H2OH O Glycoaldehyde (HCOH) C H C O C H2OH H OH C H C O C H2OH HO H Glyceraldehyde(s) Two possible isomers C H2OH C C H2OH O 1,3-Dihydroxyacetone (optically inactive) Enantiomers – non super-imposable mirror images Epimers – sugars that differ by configuration at one carbon
3/2/14 Aldoses D-and L-Isomers Tetroses Aldoses HCOH CHOH H c D-(+)-glyceraldenyde H H-C-OH -OH H-C-OH H CH2OH CH2OH D-()Treose D-(-)-Erythrose CHOH L-glyceraldehyde Tetroses Pentoses Ketoses-the "uloses" Aldoses H C CH2OH CH2OH H-C -OH H-C OH C-0 C-0 H CO H-C H-COH HO-C-H OH HO H -OH HO. H-C OH OH HO- -H CH2OH CH2OH CH2OH H-C OH CH2OH HO-d H OH ge8oge L-glycero-etrulose D-cibose D-xylose CHOH D-arabinose D-lyxose 3
3/2/14& 3& Aldoses D- and L- Isomers D-(+)-glyceraldehyde L-(-)-glyceraldehyde C H C O C H2OH H OH C H C O C H2OH HO H the&conforma1onal&& carbon,&highest8numbered&asymmetric&C& Tetroses Aldoses D-(-)-Threose D-(-)-Erythrose C H C O C HO H C H2OH H OH C H C O C C H2OH H OH H OH C2&Epimer &Not&an&Enan1omer&(complete&mirror&image)& Tetroses Ketoses - the uloses D-glycero-tetrulose D-erythrulose C H2OH C C C H2OH O H OH C H2OH C C C H2OH O HO H L-glycero-tetrulose Pentoses Aldoses D-ribose D-arabinose D-xylose D-lyxose C C C C C H2OH OH OH OH H H H H O C C C C C H2OH OH OH H H H O HO H C C C C C H2OH OH H OH H HO H H O C C C C C H2OH H H OH HO HO H H O
3/2/14 Pentoses Ketoses CH2OH CHO c=o -0 CHO H-C-OH HO-d H-C-OH CHOH H-C-OH CHOH CH.OH CHOH CH.OH CHOH CHOH etoam Hexoses but only 4 D-ketohexoses,or hexuloses Table2 Moncacchari prices CH OH CH.OH CH2OH 0 0 CH2OH 4
3/2/14& 4& Pentoses Ketoses D-ribulose (erythro-pentulose) D-xylulose (threo-pentulose) C H2OH C C C C H2OH OH OH H H O C H2OH C C C C H2OH H OH O HO H Hexoses Aldoses - there are 8 D-aldohexoses D-(+)-allose CHO C H2OH CHO C H2OH CHO C H2OH CHO C H2OH CHO C H2OH CHO C H2OH CHO C H2OH CHO C H2OH D-(+)-mannose D-(-)-gulose D-(-)-idose D-(+)-galactose D-(+)-talose D-(+)-altrose D-(+)-glucose Hexoses but only 4 D-ketohexoses, or hexuloses C H2OH O C H2OH C H2OH O C H2OH C H2OH O C H2OH C H2OH O C H2OH D-(+)-psicose D-(-)-fructose D-sorbose Natural isomer appears to be LD-(-)-tagatose
3/2/14 Two Carbonyls? No Carbonyls? Oddly-placed Carbonyls? Sugar alcohols Dialdoses odialdose"instead of"ose" e.g.,glucodialdose CH2OH CH-OH Ketoses at C2 -ulose"e.g.xylulose Ketoses elsewhere CH2OH CH2OH e.g.,at C3.called a 3-ketose or hexo-3-ulose CH.OH Diketose CHOH CHOH Diuloses- Mixed ketose and aldose Sorbatol aldoketoses,aldosuloses Sugar Alcohols Xylitol 5 carbon sugar alcohol. Many sugar alcohols exist naturally in nature approximate sweetness of especially plants sucrose. anti-&non-cariogenic .e.g.sorbitol,mannitol,xylitol,etc properties not metabolized by insulin Can also be made artificially presently fairly expensive
3/2/14& 5& Two Carbonyls? Oddly-placed Carbonyls? Dialdoses -odialdose instead of -ose e.g., glucodialdose Ketoses at C2 -ulose e.g., xylulose Ketoses elsewhere e.g., at C3, called a 3-ketose or hexo-3-ulose Diketose Diuloses - Mixed ketose and aldose aldoketoses, aldosuloses No Carbonyls? Sugar alcohols Erythritol Threitol Sorbitol Mannitol Xylitol C H2OH C H2OH C H2OH C H2OH C H2OH C H2OH C H2OH C H2OH C H2OH C H2OH (symmetrical)& Sugar&Alcohols& • Many&sugar&alcohols&exist&naturally&in&nature& —&especially&plants& • e.g.&&sorbitol,&mannitol,&xylitol,&etc& • Can&also&be&made&ar1ficially&& Xylitol • 5&carbon&sugar&alcohol.& • approximate&sweetness&of& sucrose.& • an18&&&non8cariogenic& proper1es& • not&metabolized&by&insulin& • presently&fairly&expensive.&