3/2/14carbohydratesCarbohydratesPartOneThemostabundantorganicmoleculesInitial sourceof ALLFOOD?Provide·Energy (~4Cal/g).Carbon.FiberSignificantcontributiontothepropertiesoffoodsWhereis Sugar in Food?Contributionsto FoodProperties-SweetnessNaturally found in:-Precursors ofaroma compoundsFruits, vegetables, grains, dairy products-Precursorsofcoloredcompounds-Provide textureAdded sugar found in:-CelluloseCandy, chocolate-StarchDesserts, baked goods, ice cream-PectinSoft drinks-Buildviscosityat lowconcentrationCondiments, snacksOn labels as sugar, sucrose, invert sugar,-Starchcorn syrup-Gums-Cellulosefragments
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
3/2/14Classificationsac.uPolysaccharides2carb/-Monosaccharides-Polysaccharides-Starch·Polyhydroxyaldehydes-Glucosepolymer,a-1,4-linkages,1.6branches-Polyhydroxyketones-Cellulose-Oligosaccharides-Glucosepolymer,β-1,4-linkages-Disaccharides-Pectin.Sucrose,Maltose,Lactose-Polygalacturonic acid (methyl esters)-Trisaccharides-GumsRaffinose-Carrageenans-Alginates-Tetrasaccharides-Locustbeangum-Stachyose'etc.TriosesNutritionalAvailabilitythe simplest sugars-H.6=0Readilyabsorbedandmetabolized-Glucose-FructoseHO-C-HH-C-OH-(Galactose)CH,OHCH,OH.0H.-Not Absorbed(HCOH)C-Polysaccharides (fiber)-Disaccharides (some diffusion)Glyceraldehyde(s)CH,OH-Some are hydrolyzed in the intestinal mucosaTwo possible isomersGlycoaldehyde-Prebiotic oligosaccharides (food for Probiotic bacteria)CH,OH-Fermentable oligosaccharides can lead to flatulence (gas-producingEnantiomers-c-oanaerobes)non super-imposableCH,OHmirror imagesEpimers --1,3-Dihydroxyacetonesugars that difer by configuration at one(optically inactive)carbon2
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
3/2/14AldosesTetrosesD-and L-IsomersAldoses0HHICOHH.b=0H.6=0CHOHHO-C-HH-C-OHD-(+)-glyceraldenydeH-C-OHH-C-OHCH2OHCH2OHH..0HOC-HD-(-ThreoseD-(-)-ErythroseCH2OHthe"conformationalC2EpimerL-(-)-glyceraldehydecarbon", highest-numbered asymmetric C Not an Enantiomer (complete mirror image)PentosesTetrosesAldosesKetoses-the"uloses"HH200CCH2OHCH2OHH-CH-C-OHOHHb=0H.b=0C=0C=0-OHHO-C-HH-CHO-CIHHO-CHH-C-OHHO-C-HH-C-OHH-C-OHH-COHHO-CHCH2OHCH2OHCH,OHCH,OHH-C-OHH-C-OHD-syloseCH,OHCH,OHD-glycero-tetruloseL-glycero-tetruloseD-ribose"D-erythrulose"D-arabinoseD-lyxose3
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
3/2/14PentosesHexosesKetosesAldoses-thereare8D-aldohexosesCH,OHCHOCHOCHOCHOCH,OHC-oCHOCHOCHOCHO0-0H-COHHO-C-HH-C-OHH-C-OHCH,OHCH,OHCH,OHCH,OHCH,OHCH,OHCH,OHCH,OHCH,OHCH,OH850me-(+)-0a50n6-(-)-0seeS0m6-(+)250e-(+)-098osD-ribuloseD-xylulosesouue-(+gsope-(-0e6-(+)(erythro-pentulose)40-(+)(threo-pentulose)aocHexosesbutonly 4D-ketohexoses,or hexulosesTable 2.5. Monosaccharide pricesPrice (SUS g l)Pice (SUS.gr)CH,OHCH,OHCH,OHCHOHD9L-Ooo0AldlyertoseKegycutoses0.47250430cryaro-Pentulose-68000.33threo-Pentilose1350RXylove-2.88Lyxosc一KerobexoneAldohesases189200900AllseI 1PsicostCH,OHCH,OHCH,OHCH,OHAltrose700Fructose0.05188984200.18GluconeSorbose0009(sd-(+)00e-(0MasnoscTagaoic13140Gulose.ldoseSeGlaconeoTaloxe15004
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
3/2/14TwoCarbonyls?No Carbonyls?Oddly-placedCarbonyls?Sugar alcoholsDialdoses"-odialdose"instead of"-ose"CH,OHCH,OHCHOHCH,OHCH,OHe.g.,glucodialdoseKetoses atC2"-ulose"e.g.,xyluloseCH,OHCH,OHKetoseselsewhereCH,OHe.g.,at C3,called a 3-ketose or hexo-3-uloseCH,OHCH,OHErythritolThreitolDiketoseXyitolDiulosesSorbitolMannitolMixedketoseandaldosesymtricalaldoketoses,aldosulosesSugar AlcoholsXylitol:5 carbon sugar alcohol.?Many sugar alcohols exist naturally in nature:approximate sweetness of-especiallyplantssucrose.? anti-& non-cariogenice.g. sorbitol, mannitol, xylitol, etcproperties?notmetabolized byinsulin2:presentlyfairly expensive..Canalsobemadeartificially
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.&