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

These Include Food Coloring

Flavorings and Sweeteners

Flour Improvers and Bleaches

Antioxidants

Preservatives and nutritional supplements

Sucrose ► Natural Sweetener ► Adds to calories

Natural vs. Artificial Disadvantages of natural sweeteners: ► Adds to calories (hence unsuitable for people on a diet) ► Increases blood sugar levels (hence unsuitable for diabetics)

Natural vs. Artificial Advantages of Artificial Sugars: ► Does not add to calories ► Not metabolized in the body ► Inert, harmless

Saccharine ► Also known as ortho- sulphobenzimide ► Excreted in urine ► Inert in body

Aspartame Methyl ester of aspartic acid-phenylalanine dipeptide

Aspartame As it is unstable at high temperatures, it is unsuitable for cooking. Hence it is used in cold drinks and foods.

Alitame ► More stable than aspartame ► As it is 2000 times sweeter than sucrose control of sweetness difficult

Sucralose ► Tri-chloro derivative of sucrose ► Same taste and appearance as sucrose ► Stable at cooking temperature ► Does not add to calories

Preservatives include: Table salt (NaCl) Sugar

Preservatives include: Sodium Benzoate And…… Salts of sorbic acid and propanoic acid

Sodium Benzoate ► Metabolized in the body ► Used in limited quantities

Types of detergents ► Soaps ► Synthetic detergents

Saponification The general equation for saponification is as follows: Fat + Alkali Soap + Glycerol

Saponification Fatty acids used are: ► Stearic acid ► Oleic acid ► Palmitic acid The soap is precipitated with NaCl (Why?)

Varieties of soap Bath Soap ► Better quality fat used ► Excess alkali removed ► Perfumes and colors added

Varieties of soap Floating soap Air bubbles beaten in before hardening

Varieties of soap Transparent soap ► Soap dissolved in ethanol ► Excess solvent evaporated off

Varieties of soap Medicated Soaps: Medicinal substances added

Varieties of soap Shaving soap: ► Glycerol added to prevent drying ► Rosin added which forms sodium rosinate which lathers well

Varieties of soap Laundry soap: Fillers like sodium rosinate, sodium silicate and sodium carbonate added

Varieties of soap Soap chips: Melted sheet of soap run into a cool chamber and soap scraped off in small broken pieces

Varieties of soap Soap or scouring powder: It consists of soap, abrasives like powdered pumice or finely divided sand and builders like sodium carbonate and tri- sodium phosphate.

Disadvantages of Soap Soaps 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: 2C 17 H 35 COONa + CaCl 2 2NaCl + (C 17 H 35 COO) 2 M M = Ca or Mg

Disadvantages of Soap These 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

Other Disadvantages of Hard Water ► Hair washed in hard water looks dull ► Dye does not absorb evenly on cloth washed with hard water

Advantages of Synthetic Detergents over soaps ► Have all the properties of soaps ► Can be used in both hard and soft water to give foam ► Gives foam even in ice-cold water

Types of Synthetic Detergents ► Anionic Detergents ► Cationic Detergents ► Non-ionic Detergents

Anionic Detergents Sodium salts of sulphonated long chain alcohols or hydrocarbons. Alkyl hydrogensulphates made by treating long chain alcohols with conc. H 2 SO 4 and then neutralized with NaOH CH 3 (CH 2 ) 10 CH 2 OH H 2 SO 4 CH 3 (CH 2 ) 10 CH 2 OSO 3 H(Lauryl hydrogensulphate) CH 3 (CH 2 ) 10 CH 2 OH H 2 SO 4 CH 3 (CH 2 ) 10 CH 2 OSO 3 H(Lauryl hydrogensulphate) NaOH (aq) CH 3 (CH 2 ) 10 CH 2 OSO 3 - Na + (Sodium lauryl sulphate) NaOH (aq) CH 3 (CH 2 ) 10 CH 2 OSO 3 - Na + (Sodium lauryl sulphate)

Anionic Detergents Anionic Detergents are mainly used in household cleaning agents

Cationic Detergents ► These 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. E.g..: Cetyl tri-methyl ammonium bromide

Cationic Detergents Cationic detergents have germicidal properties and are expensive. These are usually used in hair conditioners.

Non-Ionic Detergents These detergents do not contain any ion in their constitution. CH 3 (CH 2 ) 16 COOH + HO(CH 2 CH 2 O) n CH 2 CH 2 OH -H 2 O CH 3 (CH 2 ) 16 COO(CH 2 CH 2 O) n CH 2 CH 2 OH -H 2 O CH 3 (CH 2 ) 16 COO(CH 2 CH 2 O) n CH 2 CH 2 OH

Non-Ionic Detergents These detergents use the same cleaning mechanism as soaps.

Disadvantage of Synthetic Detergents 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.