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Food Cnemistw Option F Food Groups F i Food amp Nutrients Food any supstanoe wnetner prooessed semiprooessed or raw wnion is intended ior numan oonsumptioni and inoiudes drinks onewing gum and any supstanoe wnion nas peen used in tne manuiaoturei preparation or treatment oi quotiood put does not inoiude oosmetios or topaooo or supstanoes used oniy as drugs Nutrients any supstanoe optained irom iood and used py tne pody to provide energy to reguiate gromrtn and to maintain and repair tne pody s tissues Tnese inoiude proteinsi fats and oils carbohydrates vitamins minerals and water2om3i Lipids fats and oils 10 20 Soiupie in non poiar soivents Fats wnion are made irom tne eiements oarpon nydrogen and ongeni provide a more oonoentrated energy souroe tnan oarponydratesi Tne oarpon atoms are iess oxidized as tne moieouies nave iewer ongen atoms in tneir moieouies and so more energy is reieased wnen tne moieouies are oompieteiy oxidized to oarpon dioxide and water Tne iat stored in adipose tissue provides insulationi wnion regulates the temperature oi tne podyi and protective covering ior some parts oi tne podyi Esters oi propane i i2i8 trioi giyoeroi and iong onain oarpowiio adds oaiied iatty aoids iorm iipids as ioiiows f 0 ii culou 0 C RI 393 cage 2 R1 r 0 F ClIOH i R C 0 cH 0 3H0 HO 3 R3 H CHIOH C CH2O C R3 HO C R3 ii tne tnree iatty aoids in a trigiyoeride are tne same it is oaiied a simpie giyoeride ii tney are diiierenti it is oaiied a mixed giyoerideine onemioai and pnysioai properties oi tne iat depend on tne nature oi tne iatty aoid group FFats wnion are animai in origin are soiid at room temperature and nave saturated F onains with no oarpon oarpon doupie ponds Oiis wnion derive irom piants and rrsn nave unsaturated Fi onains and are iiduid at room temperature Carbohydrates 60 Carbonydrates nave tne embirioai tormuia Cmlti i20gtnTh main tunotion ot oarbonydrates in our bodies is as an energy SQUIKCEI Piants are tne main source ot dietary oarbonydrates wnion are broduoed trom oarbon dioxide and water by bnotosyntnesis 6002 6H2O gt CHi2O 6O2Lignt subbiies tne energy needed tor bnotosyntnesis Piants are abie to syntnesize a iarge number ot ditierent oarbonydrates Sugars are iow moiar mass oarbonydrates wnion are orystaiiine soiids and dissoive in water to give sweet SO U ti Sl Monosaooharides Tne simbiest oarbonydrates are oaiied monosaoonaridesi witn tne embirioai tormuia CH2O Tney are eitner aldehydes aidose or ketones ketose witn one oarbonyi groub 30 and at ieast two nydrowi OH groubsi Pentoses nave tive oarbon atoms and nexoses nave six oarbon atoms Exambies ot monosaoonarides inoiude giuoose truotose and IKib Sl Tney are soiubie in water as tne nydrowi OH tunotionai groubs are abie to torm nydrogen bonds witn tne water moieouies Monosaoonarides are tne buiiding biooks ot disaoonarides and boiysaoonarides H 0 Cr Dgiuoose is tne most imbortant monosaoonaride as it is H c2 on neoessary tor oeiiuiar resbirationiit nas tne straignt onain HO L H tormuia snown beiow Tne oarbon atoms are numbered i starting witn i at tne tob in tne oarbonyi groub and ending H C OH witn 6 at tne bottom H 3915 OH C H2OH Disaooharides Disaoonarides are tormed in oondensation reactions by tne eiimination ot one water moieouie trom two monosaoonarides Tnere are many disaoonarides known but tnose imbortant to tne tood industry are maitose iaotose and suorose Polysaooharides Poiysaoonarides are oondensation boiymers tormed trom monosaoonarides witn tne eiimination ot water moieouies Giuoose is tne most imbortant monomer ot tne naturaiiy ooourring boiysaoonaridesPoiysaoonarides aot as energy stores Staron is tne boiysaoonaride in wnion giuoose is stored in biants and giyoogen is used as an energy store in animai oeiis Ceiidiose a boiysaoonaride nnade tronn gidoose nnoieodies is a nnaior oonnbonent ot biant oeii waiis As ndnnans do not nave tne neoessary enzymes to break tne iinks between tne gidoose nnoieodies it oannot be digested and nas no ndtritionai yaidei it is noweyeri yaidabie in tne diet as tibre as it gives bLiiilt to tood wnion aids its bassage tnrodgn tne aiirnentary oanai Proteins 20 30 Proteins are yitai oornbonents ot aii iite Tney are natdrai boiyrners rnade trorn oonnbinations ot 20 ditierent 2 annino adds As annino aoids nave botn a oarbowiio aoid grodb and an annino grodb tney are abie to undergo oondensation reaotions peptde H 0 H H H 0 b H 0 H i ii I i Ii3N CL C OH HN C C OH e H3N o cL1T C L C OH H0 i R H R R H R Tne broddot a dibebtidei is an annide nnade db ot two annino aoids joined by a bebtide bond or bebtide iinkagei Tne seoondary strdotdre ot a brotein desoribes tne way in wnion brotein onains toid or aiign tnennseiyes by intrannoieodiar nydrogen bonding between ditierent grodbs at ditierent bositions aiong tne brotein onain Tne tertiary strdotdre desoribes tne oyeraii tnreedinnensionai snabe ot tne brotein and is deternnined by a range ot interaotions sdon as Hydrogen bonding between boiar grodbs on tne side onain Sait bridges ionio bonds tornned between NH2 and COOH grodbs Diboie diboie interaotions Van der Waais toroes between non boiar grodbs Disditide bridges tornned between two oysteine nnoieodies tronn ditierent bositions aiong tne boiyrner onain Aninnai brotein is generaiiy nnore yaidabie ndtritionaiiy tnan yegetabie brotein beoadse aninnai brotein oontains tne tdii oonnbiennent ot essentiai annino adds Tnese are annino aoids tnat nndst be sdbbiied in tne diet beoadse tney oannot be nnade in tne body yegetabie broteini in generai tends to iaok one or more ot tne essentiai annino adds Cereai brotein tor exarnbie iaoks iysine wnion is an essentiai arnino add Fats lt3 Oiis F2 Most natdraiiy ooodrring tats oontain a nnixtdre ot SEitLitEitd nnonodnsatdrated and boiybnsatdrated tatty aoids witn ditierent onain iengtns Tney are dassitied aooording to tne bredonninant tybe ot dnsatdration bresent Saturated Fatty Acids The saturated iatty acids which are oiteh ahlmal lh orlglh are all carbonllc acids with the geheral iormula Chl 2hiCO l l The carboh chalh is made irom ohly slhgle carboh carboh bohdsl The carboh atoms are bohded lh a tetrahedral arrahgemeht which allows the chaihs to pack closely together The yah der Waals iorces are suiilclehtly strohg betweeh the chaihs to make the compouhds solid at room temperature Llholelc acid is ah essehtiai iatty acid lh our diet as our body is uhable to syhthesize it The absehce oi the essehtiai iatty acids lh Unsaturated dp Aclds the diet may result ih disorders such as CZiTTEi Uhsaturated iats cohtalh the carboh carboh double bohd This produces a 39klhk lh the chalh which preyehts the molecules irom packlhg closely together ahd reduces the lhtermolecular iorcesl Uhsaturated oils which are oiteh vegetable lh orlglh are lldulds The greater the humber oi CC double bohds the greater the separatloh betvyeeh the chaihs ahd the lower the meltlhg DOil Ti O Triglyceride molecules cah be thought oi as ll haylhg 39tuhlhg iork structures with the three 0 C1420 C Rt lohg limbs belhg the iatty acid chaihs lh a llduld R T OCl1 0 oil the triglyceride molecules are orlehted 1 3 l quot rahdomly to ohe ahother ahd are cohstahtiy lh CH1OC R i TiOilOl T lh a chstalllhe iat they are tightly quot packed lh a regular repeatlhg pattem with helghborlhg triglycerides lhteractlhg through yah der Waals iorcesAs iats cohsist oi a mixture oi triglycerides they do hot have sharp meitihg polhts but melt over a rahge oi temperatures Geherally the more uhsaturated the iat the lower its meitihg polht ahd the less chstalllhe it will be The meitihg polht oi the iat is a key iactor lh determlhlhg which iat is used lh a iood Mainly saturated fats Mainly monounsaturated Mainly polyunsaturated solids oils liquids oils liquids coconut butteriat beei iat olive oil canola oil peanut saiilower sunflower and tallow oil soybean oils corn oil fish oil linoleic and linolenic acids Essential fatty acids cannot be synthesized by the body Omega 8 polyuhsaturated iatty acids iouhd ior example lh iish oils ahd ilax seeds have beeh shovyh to be llhked to reduced risk oi cardiovascular disease as well as to optimum heurologlcal deyelopmehtThe term omega 8 reiers to the positioh oi the iirst double bohd lh the molecule relative to the termlhal 2 CH3 group Cis and trans forms of unsaturated fats As tne oarbon oarbon double bond does not allow tree rotationi unsaturated tatty aoids exist in two torms CH3 CH3 CH3 H O C l C Cl1 C C CH CH OH 2 2 3 2 Pn X g CH C quot H CH3 CH3 C CH CH CH cc CH CH OH 0 n g H Tne trans torm nas tbe nydrogen atoms on ditierent sides ot tne oarbon oarbon double bondiibe ois torm nas botb nydrogen atoms on tne same side ot tbe double bondine ois and trans isomers are exambles ot geometrio isomers As tne moleoules ot tbe ois isomer oannot easily arrange tnemselyes side by side to solidity tbey tend to baye lower melting boints tban tbe oorresbonding trans isomer Tne ois isomer is tne most oommon torm ot unsaturated tat tne trans torm only ooours in animal tats and in brooessed unsaturated tats suob as margarine Tbe trans isomers are similar to saturated tats in tbat tbey lead to a greater risk ot beart disease owing to tne broduotion ot low density LDL obolesterol Tney are also harder to metabolize and to exorete trom tne body tnan tbeir ois isomers and so build ub to dangerous levels in tatty tissue Tbe trans isomer is also less etieotiye as an energy souroei Stability Of Fats Hydrolysis Of Fats Oils and tats deyelob an unbleasant or ranoid smell it tbey are kebt too longFanoidity is tbe beroebtion ot tlayors in libidsitbose tnat our senses beroeiye as oti beoause tbey nave a disagreeable smell taste texture or abbearanoeOne oause ot ranoidity is tne release ot tatty aoids broduoed during tne nydrolysis ot tne tat by tne water bresent in toodi Free tatty aoids are generally absent in tne tats ot living animal tissue but oan torm by enzyme aotion atter tbe animal bas died Fats are bydrolyzed in tbe bresenoe ot neat and water to tneir tatty aoids and brobanel 28 triol glyoerol in tbe reverse ot tbe esterifioation reaotion W o Palmitio steario and oleio aoids are CHIC C RI CHEOH Ho C RI broduoed during tne nydrolysis ot W 0 obooolate and give it an oily or tatty CHOltC R2 3420 4 CHOH Hosc kl tlayor Laurio aoid gives balm and V 0 oooonut oil in ooooa butter substitutes cH2ocR3 CHZOH HocR3 a soabytlayor Butanoio nexanoio and fat glycerol fmadd ootanoio aoid in ranoid milk Hydrogenation Oi Fats pg p4 03 gzur Hydrogen oan be added aoross I C C 1l 11 3 H c cquot H tne oarbon oarbon doubie bond to H 0 H 14 deorease tne ievei oi unsaturationi ibis is an imbortant reaotion as it inoreases tne meiting boint tne nardness and onemioai stabiiity oi tbe iat it is used oommeroiaiiy to oonvert iiduid oiis into soiid margarine and sbreads Hydrogenation is oarried out at i4iO 225 GO in tne bresenoe oi a iineiy divided metai oataiyst Zn Cu Ni Tne degree oi saturation oan be oontroiied by vaning tne bressure oi tne nydrogen and tne nature oi tne oataiyst Advantages Disadvantages onanges a iiduid oii to a semi soiid or mono and boivunsaturated iats are soiid to make tbe meiting boint oi an neaitbier ior tbe neart tnan saturated iats unsaturated iat more iike tnat oi a saturated iat deoreases tne rate oi oxidation stabiiity in bartiai nydrogenation trans iatty aoids inoreases Witn inoreasing saturation oan iorm inoreases nardness trans iatty aoids are bard to metaboiizei 1 1 aooumuiate in iatty tissue are diiiiouit to COWONS The fee am DQSUCW exorete irom tne body inorease ieveis oi ltSW 9SSgt LDL bad onoiesteroi and are a iovv duaiity energy souroe Sneii Liie F3 A iood reaones its sneii iiie wnen it no ionger maintains tne exbeoted duaiity desired by tne oonsumer beoause oi onanges in iiavori smeiii texture and abbearanoe ooiori mass or beoause oi miorobiai sboiiage Food oontains enzymes and is tnereiore susoebtibie to onange and sboiiage Tnere are two tybes oi iood sboiiage autoiysis and miorobiai sboiiage Autoiysis is tne breakdovvn oi iood by tne enzymes bresent in tne iood and oauses tne reiease oi nutrients irom tne oeiis Tnese nutrients tnen beoome avaiiabie to mioroorganismsi wnion ieed and muitibiy eventuaiiy making tne iood unaooebtabiei Tne sneii iiie debends on tne tybe oi iood tne temberaturei tne moisture oontent tne ongen oontent and otner iaotors suon as tne bH The enzymatic prowning of apples fruits that contain phenols is the action of an enzyme that forms duinone through oxidation which can then undergo polymerization to give the provvn product called tanninsThis prowning reaction can pe slowed down using reducing agents such as sulfur dioxide and ascorpic acid Factors That Affect The Shelf Life And Quality Of Food Changes in the water content Water is typically the most apundant constituent in food it is ponded to the proteins and carpohydrates in food py hydrogen ponding and plays a critical role in determining food duality as it makes food juicy and tender A reduction in water content can affect the texture lead to the loss of nutrients and increase the rate of enzymatic prowning and hydrolytic rancidityi its presence in dried food can also produce undesiraple chemical changes as it increases the rate of the degradation of the food py microorganisms Water can pe removed from food py either dning or smoking Salting or adding sugars also reduce the water content py osmosis Omgen and water from the air can pe prevented from reacting with food if it is wrapped in an airtight cover or stored in a vacuum or unreactive gas such as nitrogen pH The pH has a marked effect on the activity of most enzymes and the action of microorganisms Bacteria reduire suitaple nutrients and minerals and most prefer a neutral or slightly alkaline medium from around 454 0 Reducing the pH inhipits micropial and enzymatic activity and helps preserve food Ethanoic acid is used for food such as onions py pickling and acids such as ascorpic citric and malonic acids which are naturally found in fruit and vegetaplesi are added to food to control enzymatic prowning A numper of weak acids such as sorpic and penzoic acids are used as preservatives as they have little effect on flavor Although a given concentration of a strong acid is more effective in lowering the pH than a weak acidi weakly dissociated acids are petter preservatives This suggests that the preservation is not purely a pH effect put that the undissociated acid has some inhipitor role Light Light initiates free radicle mechanisms like the oxidation of fats and oils which leads to rancidity and of other nutrients such as vitamins Exposure to light can also cause the natural color of a food to fade Storing food in the dark or using colored or opadue packaging which prevents light from passing through to the food will stop photo oxidation of fats and other photochemical free radical reactions Temperature An increase in temperature can increase the rate ot the chemicai reactions which resuit in tood spoiiage An increase in temperature can aiso atiect the water content and thus the texture ot the tood it the temperature is raised apove 60 C the enzymes are denatured as the secondan and tertian structure ot the protein is disrupted This can reduce the rate ot the degradation reactions Dain products are otten retrigerated as iow temperatures siovv down the rate ot the iipase hydroiysis which produces rancidityi Food Presenation and Processing Antioxidants An antioxidant is a supstance that can pe added to tood to increase its sheit iite py deiaying the onset ot oxidative degradation They act as radicie duenchersi one that reacts with the tree radicie and prevents the reaction trom continuing Antioxidant Source vitamin C ascorpic acid citrus truits and most green vegetapiesi vitamin E a tocopheroi nuts seeds soya peans vvhoie grains and some vegetapie oiis iike canoia oii peta carotene vegetapies such as carrots and proccoii as vveii as truits such as tomatoes and peaches Seienium tish sheiitish meaty eggs and grains Synthetic Antioxidants Aimost aii have phenoiic type structures that is they have a hydrowi group attached to a penzene ring a structurai teature that is not tound in naturaiiy occurring antioxidants They can have harmtui side etiects Natural Antioxidants Many supstances traditionaiiy used in ditierent cuitures as promoting good heaith are rich in naturai antioxidants Such toods inciude green tea turmeric oregano piueperries cranperries and dark chocoiate Many ciaims are made tor these such as the iovvering ieveis ot LDL choiesteroii piood sugar ieveis and high piood pressure as vveii as preventing cancerous ceii deveiopment put they have not peen supiected to the stringent tests ot modern science Advantages Disadvantages reduce tne risk ot cancer and neart consumers berceive svntnetic disease by innibiting tne tormation oi tree antioxidants to be iess sate because radicais tnev are not naturaiiv occurring in tood vitamin C is vitai tor tne broduction ot naturai antioxidants can add coior and an normones and coiiagen attertaste to tood and can be iess etiective at siovving down tbe rate ot ranciditv tnan svntbetic antioxidants margarine to give coiour veiiow and acts svntnetic antioxidants are tood additives as a brecursor tor vitamin A and need to be reguiated bv boiicies and iegisiation to ensure tneir sate use in tood boiicies regarding tne iabeiing and sate use ot tood additives can be ditiicuit to imbiement and monitor esbeciaiiv in deveiobing countries and internationaiiv Free Radicle Quenchers Tnev react witn tne tree radicais bresent and broduce iess reactive tree radicais Tnere are aiso manv naturaiiv occurring antioxidants sucn as tocobneroi vitamin E tnat can be used as tree radicai duencners and many beobie breter tnese to svntnetic antioxidants Chelating Agents Free radicais mav be tormed bv tne reaction ot transition metai ions witn tne nvdroberoxides initiaiiv broduced bv tne autooxidation reaction Cneiating reagents torm ven stabie combiex ions witn transition metais and nence reduce tne occurrence ot tnese reactions Many biants sucb as roseman tea and mustard contain naturai cneiating agents Saits ot EDTA etnvienediaminetetraacetic acid are sometimes added as artiticiai cneiating agents Reducing Agents Reducing agents eiectron donors can react with botn ongen in tne tood and witn tne nvdroberoxides initiaiiv broduced bv autooxidation Exambies ot naturaiiv occurring reducing agents inciude ascorbic acid vitamin C and carotenoidsi Artiticiai breservatives tnat are reducing agents sucn as suitur dioxide suitites and nitrites may act in a simiiar manner Color Fit Dye A tood grade syntnetlo watersoluble oolorant Plgrnent A naturally ooourrlng oolorant tound ln tne oells ot blants and anlrnals Botn groubs ot oonnbounds ovye tnelr oolour to tne taot tnat tney absorb oertaln treduenoles ot ylslble llgnt wnllst retleotlng otners Wnlon are able to stlrnulate tne retlna ln tne eye For exannble green sblnaon looks green beoause lt absorbs red llgnt and blue llgnt but does not absorb and nenoe retleots green llgnt Anthooyanins Tne rnost Wldely ooourrlng blgrnents ln blants Resbonslble tor blnk red burble and blue oolors ln trults and vegetables lnoludlng oranberrlesl blueberrles strawberrles and rasbberrlesl Sonne tybloal antnooyanlns are snovyn below lt wlll be noted tnat tney all nave yery slnnllar Brlng CeCsCe struotures wltn conjugated double bonds but tney yary ln tne nunnber and bosltlon ot tne nydrowl groubs and alkow slde onalns Tney nave a nnoblle bl eleotron oloud tnat oan absorb ylslble llgnt Tne struoture ot antnooyanlns ls yery debendent on bH not only beoause ot aold base etteots but also beoause ot tne etleot ot bH on tne ease ot nydratlon reaotlons As a result tne oolor ot toods oolored by antnooyanlns oan vary slgnltloantly durlng tne oooklng brooess esbeolally wnen nnlxed wltn aoldlo or alkallne lngredlents Antnooyanlns torrn oornblex lons Wltn rnetal lons suon as Fe3t and Al3t nenoe brolonged oontaot wltn tnese nnetalsl tronn wnlon sauoebans are otten nnade may also oontrlbute to onanges ln oolor durlng tne oooklng brooess At nlgn tennberatures llke nnany organlo oonnboundsl antnooyanlns deoonnbose and tnls may lead to brownlng ln sonne oooklng brooesses Tnere are tour olosely related struotural tornns ot antnooyanlns wnlon are otten ln edulllbrlunn tne exaot bosltlon debendlng on taotors suon as bH and tennberaturel wnlon allovys tnese oonnbounds to be used as add base lndloators Tne nnost brlgntly oolored tornns A and B belovy noweyer are stable at low tennberature and tor A at low bH Tne absorbtlon sbeotra ot tne antnooyanlns tneretore yary Wltn bH At low bH tne tlawllurn oatlon AH bredornlnates and tne rnlxture ls red at neutral bH yalues tnere ls a sutllolent oonoentratlon ot nydroxlde lons tor tnls to nydrolyse and tne solutlon beoonnes alnnost oolourless as lt ls oonyerted to tne oarblnol bseudobase B and onaloone C At even greater bHs tne tlawllurn oatlon AH ln edulllbrlurn Wltn tnls ls oonyerted to tne dulnoldal base A so all tne edulllbrla are snltted to yleld tnls broduot and tne solutlon turns blue A V AW 1 B T C QUlWOP39ld aw jUnj Cafbl ol base Cfwakone b39Je red COIOUYIESS COOdfe55 Ahthooyahlhs have rhahy hydrowl groups attaohed to thelr rlhg struoture These oah hydrogeh bohd to water rholeoules ahd as a result ahthooyahlhs tehd to be water soluble Carotenoids These are Wtdely touhd lh all llylhg thlhgs espeolally th algae They are respohstble tor yellow orahge ahd red oolors ahd as well as belhg respohslble tor the ootor ot oarrotsl they oause the ootor lh bahahas torhatoes ahd S8tTTtOl t Beoause thelr low levels lh grass are oohoehtrated lh rhllk tats they also glye butter lts ootor Caroteholds also have hutrltlohal value beoause they oah be oohyerted lhto yltarhlh A as well as belhg etteotlye ahtloxldahts The essehtlal teature ot oaroteholds ls the lohg hydrooarboh Cltailt whloh may also have rhethyl groups attaohed lh sorhe oases there may be rlhg struotures at the ehds ot the ohath lh other oases hot Slrhllarly sorhe oaroteholds have hydrowl groups hear the ehd ot the ohath or oh the rlhg whereas others sorhetlrhes oalled oarotehes They are stable up to 5000 ahd lh the pH rahge ot 2 7 ahd theretorel are hot degraded by rhost torrhs ot prooessthg Wlth heatlhg the haturally ooourrthg trahs lsorher rearrahges to the ols iSOl Ttt The presehoe ot rhultlple uhsaturated oarboh oarboh double bohds TTtamptltS oaroteholds susoeptlble to oxldatloh oatalyzed by llghtl rhetals ahd hydroperoxldes Oxtdattoh results lh the bleaohthg ot ootor loss ot yltarhlh A aottytty ahd ott odors Caroteholds have a lohg hydrophoblo hydrooarboh ohath ahd the hydrowl groups oh the rlhgs are hot suttloleht to oohter water solubllltyl so oaroteholds are soluble lh olls ahd tats Astaxanthin lt ts a red ptgrheht that ts preseht as a oorhplex Wtth proteth gtyes the blue or greeh hue touhd lh llye lobsters ahd orabs ahd the Dtl ttlt ootor ot S tllTtOlt Hlgh terhperatures dtsrupt the bohdthg to the proteth hehoe the startllhg ohahge lh ootor wheh these ahlrhals are COOtltd lt aots as ah 8tl tttOXtdal tt hehoe the health behetlts asorlbed to eatthg the shells ot shrlrhps ahd pravyhs Chlorophyll The rhalor llghtharyestlhg plgrhehts touhd lh greeh plahts Chlorophyll a ahd ohlorophyll b Whloh dltter ohly lh whether a stde ohath ts a rhethyl group at or ah aldehyde group b Reaction witn neat depends on pHln a basic solution pH 9 cnloropnyll is stable and in an acidic solution pH 8 it is unstable Wnen neated tne cell membrane ot tne plant deteriorates releasing acids wnicn decrease tne pH Tnis results in tne magnesium atom being displaced by two nydrogen ions resulting in tne tormation ot olive brovvn pneopnytin complex Tnis cell degradation during neating also makes tne cnloropnyll more susceptible to pnotodegradationi Heme it is a red pigment tound in red blood cells and muscle tissue Tne essential teatures ot botn cnloropnyll and neme are tne planar ring systems in wnicn tne metal ion is bonded to tour nitrogen atoms wnicn act as ligands Tnis is reterred to as a porpnyrin ring in muscles neme is tound associated witn myoglobini a protein molecule and tnis nas a purplisnred color it binds easily to ongen molecules nence its role in ongen transportation and tnis results in a color cnange to brignt red A mucn slower reaction Witn ongen called autooxidation results in tne oxidation ot tne iron trom ironll to ironlll torming metmyoglobin and tne color cnanges to a brownisn red color wnicn is considered less desirable llbO2 llb llllb f 39 oxymyoglobin myogbbin metmyoglobin red Fe purplered Fe2 brown Fe3 Tne stability ot color and tne rate ot brown MMb tormation trom autooxidation can be minimized it tne meat is stored in conditions tree ot ongen by using packaging tilms witn low gas permeabilities Air is removed trom tne package and a storage gas i 00 CO2 is injected The type of colorant permitted for use varies greatly among countries Since international trade is becoming increasingly important color legislation is now of international concern Tnese compounds absorb lignt in tne visible region ot tne spectrum and nence appear colored because tney all nave extensive systems ot delocalized rtbonding or extensive conjugated system Maillard Reactions Genetioaiiv Modi ed Food F5 A genetioaiiv modi ed tood is one derived or broduoed trom a genetioaiiv modi ed organism Tne tood oan be substantiaiiv di erent trom or essentiaiiv tne same as tne oonventionai tood in terms ot oombosition nutrition taste smeii texture and tunotionai onaraoteristios Advantages Disadvantages Crobs Ennanoed taste and duaiitv Links to inoreased aiiergies tor beobie reduoed maturation time inorease in invoived in tneir brooessing nutrients and vieid imbroved resistanoe to disease bests and nerbioides enrionment ot rioe Witn vitamin A Animais inoreased resistanoe Tne risk ot onanging tne oombosition ot broduotivitv and teed e ioienov better a baianoed diet bv aitering tne naturai vieids ot miik and eggs imbroved animai nutritionai duaiitv ot f dS neaitn Environment quotFriendiv bio nerbioides and bio inseotioides oonservation ot soiii Water and energv imbroved naturai waste management Texture F 6 Disbersibie Svstem A disbersed svstem is a kinetioaiiv stabie mixture ot one bnase in anotner iargeiv immisoibie bnase SusbensionSoi Tne disbersed bnase is a soiid and tne disbersion medium is a iiduid Gei Tne disbersed bnase is a iiduid and tne disbersion medium is a soiid Emuisions Tne disbersed bnase is a iiduid and tne disbersion medium is a iiduidi Foam Tne disbersed bnase is a gas and tne disbersion medium is a iiduidi Emulsifierz Heibs witn tne tormation ot emuisions and toams as it aots as tne interiaoe suriaoe between tne iiduid soiid and gas bnases in tne disbersed svstem Tnev are soiubie in tats and water Tnev nave a nvdrobniiio and nvdrobnobio end Leoitnin is a oommon emuisi er tound in egg voiks Tnev nave to be beat or wnibbed so tne suriaoe area is maximized on wnion tne suriaotant emuisi er oan be adsorbed Stabiiisers are o en aiso added to stabiiize disberse states inorganio bnosbnatesi suon as trisodium bnosbnatei are e eotive at stabiiizing emuisions tnat brevent tnem torm sebarating out Minute traoes ot metai trom bowis oan aot as stabiiizers Peotin is a naturai emuisi er and geiatin is a naturai stabiiizer Stereo Chemtstry th Fooo F9 Apsotute Cohttgurattoh tt ts the aotuat oohttgurattoh or arrahgemeht ot the tour groups arouhg the asymmetrto or ohtrat CatbO D ahg L system tt ts mathty used tor oarpohygrates ahg amtho aotgs H 0 0CH For sugars Look at the T Mirror images moteoute through the oarpoh C c ohath wtth the CO pothtthg away L won Ho 1 tt the ow ts oh the rtght tt ts a D HOCH H H CHv0H tsomer ahg tt tt ts oh the tett tt ts the L tsomer D glyceraldehyde L glyceraldehyde Figure 1720 D and L forms of glyceraldehyde N Nil Looking along the C H bond C with the H pointing away C Ami dockwise 39 quot COOII R C HOOC RquotI1 The moteoute ts ytevyeg wtth the OH pohg pothtthg away trom the opseryer tt the groups DOOR R NR2 where R ts the stge ohath are arrahgeg otoomtse arouhg the oarpoh atom theh tt ts the Dtorm tt ahttotoomtse tt ts the L torm Appttoapte tor amtho aotgs CORN rute R S systemOP system Groups are arrahgeg th the order ot thoreasthg atomto LttTtbtS Wheh the ttrst atom ts the same oohstger the seoohg atom ahg mutttpty tts atomto humper py the humper ot bO dS Look at tt wtth the towest rahkthg moteoute away tt tt georeases th a otoomtse gtreottoh theh tt ts a R ehahttomer othervytse tt ts ah S ehahttomer C11 C31 cm 213 3 439 t Murror tmages T 39 C CIOCKWISQ C Antclockwise m H Br 939 HI 39 U1 Br C11 C11 Br tnantuomer T Enantnomer 2 Enantiomer 1 Enantiomer 2
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