General Outline We will be looking at: ► Food Chemicals ► Detergents

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    01-Jan-2016

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<ul><li><p>General OutlineWe will be looking at:Food ChemicalsDetergents</p></li><li><p>These Include</p><p>Food Coloring</p></li><li><p> Flavorings and Sweeteners</p></li><li><p>Flour Improvers and Bleaches</p></li><li><p>Antioxidants</p></li><li><p>Preservatives and nutritional supplements</p></li><li><p>Sucrose</p><p>Natural SweetenerAdds to calories</p></li><li><p>Natural vs. ArtificialDisadvantages of natural sweeteners:Adds to calories (hence unsuitable for people on a diet)Increases blood sugar levels (hence unsuitable for diabetics)</p></li><li><p>Natural vs. ArtificialAdvantages of Artificial Sugars:Does not add to caloriesNot metabolized in the bodyInert, harmless </p></li><li><p>Saccharine</p><p>Also known as ortho-sulphobenzimideExcreted in urineInert in body</p></li><li><p>Aspartame</p><p>Methyl ester of aspartic acid-phenylalanine dipeptide</p></li><li><p>Aspartame</p><p>As it is unstable at high temperatures, it is unsuitable for cooking. Hence it is used in cold drinks and foods.</p></li><li><p>Alitame</p><p>More stable than aspartameAs it is 2000 times sweeter than sucrose control of sweetness difficult</p></li><li><p>Sucralose</p><p>Tri-chloro derivative of sucroseSame taste and appearance as sucroseStable at cooking temperatureDoes not add to calories</p></li><li><p>Preservatives include:</p><p>Table salt (NaCl)</p><p>Sugar</p></li><li><p>Preservatives include:Sodium Benzoate</p><p>And</p><p>Salts of sorbic acid and propanoic acid</p></li><li><p>Sodium Benzoate</p><p>Metabolized in the bodyUsed in limited quantities</p></li><li><p>Types of detergentsSoapsSynthetic detergents</p></li><li><p>Saponification</p><p>The general equation for saponification is as follows:Fat + Alkali Soap + Glycerol</p></li><li><p>SaponificationFatty acids used are:Stearic acidOleic acidPalmitic acid</p><p>The soap is precipitated with NaCl (Why?)</p></li><li><p>Varieties of soapBath Soap</p><p>Better quality fat usedExcess alkali removedPerfumes and colors added </p></li><li><p>Varieties of soapFloating soap</p><p>Air bubbles beaten in before hardening</p></li><li><p>Varieties of soapTransparent soap</p><p>Soap dissolved in ethanolExcess solvent evaporated off</p></li><li><p>Varieties of soapMedicated Soaps:</p><p>Medicinal substances added</p></li><li><p>Varieties of soapShaving soap:</p><p>Glycerol added to prevent dryingRosin added which forms sodium rosinate which lathers well</p></li><li><p>Varieties of soapLaundry soap:</p><p>Fillers like sodium rosinate, sodium silicate and sodium carbonate added</p></li><li><p>Varieties of soapSoap chips:</p><p>Melted sheet of soap run into a cool chamber and soap scraped off in small broken pieces</p></li><li><p>Varieties of soapSoap or scouring powder:It consists of soap, abrasives like powdered pumice or finely divided sand and builders like sodium carbonate and tri-sodium phosphate. </p></li><li><p>Disadvantages of SoapSoaps cannot work in hard water. This is because hard water contains calcium and magnesium ions. These react with soaps to form insoluble Ca and Mg soaps when soaps are dissolved in hard water.The reaction is as follows:2C17H35COONa + CaCl2 2NaCl + (C17H35COO)2MM = Ca or Mg</p></li><li><p>Disadvantages of SoapThese separate out as scum and are useless for washing. These make washing harder as they form a gummy mass which adheres to cloth, preventing cleaning action of soap </p></li><li><p>Other Disadvantages of Hard Water</p><p>Hair washed in hard water looks dullDye does not absorb evenly on cloth washed with hard water</p></li><li><p>Advantages of Synthetic Detergents over soaps</p><p>Have all the properties of soapsCan be used in both hard and soft water to give foamGives foam even in ice-cold water</p></li><li><p>Types of Synthetic DetergentsAnionic DetergentsCationic DetergentsNon-ionic Detergents</p></li><li><p>Anionic DetergentsSodium salts of sulphonated long chain alcohols or hydrocarbons. Alkyl hydrogensulphates made by treating long chain alcohols with conc. H2SO4 and then neutralized with NaOH</p><p> CH3(CH2)10CH2OH H2SO4 CH3(CH2)10CH2OSO3H(Lauryl hydrogensulphate) NaOH (aq) CH3(CH2)10CH2OSO3-Na+(Sodium lauryl sulphate) </p></li><li><p>Anionic Detergents</p><p>Anionic Detergents are mainly used in household cleaning agents</p></li><li><p>Cationic DetergentsThese are quaternary ammonium salts of amines with acetates, chlorides or bromides as anions.It is called cationic as the cationic part posses long hydrocarbon chains and positive charge on nitrogen atom.</p><p>E.g..: Cetyl tri-methyl ammonium bromide </p></li><li><p>Cationic Detergents</p><p>Cationic detergents have germicidal properties and are expensive. These are usually used in hair conditioners.</p></li><li><p>Non-Ionic Detergents</p><p>These detergents do not contain any ion in their constitution.</p><p>CH3(CH2)16COOH + HO(CH2CH2O)nCH2CH2OH -H2O CH3(CH2)16COO(CH2CH2O)nCH2CH2OH</p></li><li><p>Non-Ionic Detergents</p><p>These detergents use the same cleaning mechanism as soaps.</p></li><li><p>Disadvantage of Synthetic Detergents</p><p>If the detergent molecule is highly branched, it is difficult to degrade by bacteria, leading to accumulation in the environment, i.e. they are non-biodegradable.</p></li></ul>