Chemistry in Everyday Life Lecture-4
Lecture plan
Food additives
Artificial sweeteners
Antioxidants
Food colorants
Chemistry of cleansing agents
What are food additives
Chemical or ingredients which are added to a food for several purposes
Preserving flavour
Improving taste
Improving appearance
Enriching
Nutritional value
Classification
Food colours
Flour improvers antistaling agents and bleaches
Sweeteners
Preservatives
Fat emulsifiers and stabilising agents
Nutritional supplements such as minerals, vitamins and amino acids
Sweetener classification
Sweet-tasting agents
Nature
Natural
found naturally
Great Nutritional value
Artificial
produced synthetically
Little or no Nutritional value
Popular artificial sweeteners
For instance
How to measure sweetness potency
Measurement of sweetness potency
Measure relative to a standard concentration of sucrose
0.025 % of aspartame is equivalent in sweetness to 5% sucrose
$\text { Potency }=\frac{5}{0.025}=200$
At 2% sucrose solution potency $=625$
At 10% sucrose solution potency $=110$
Increasing the concentration no longer produces
Increasing sweetness
Respons asymtotically approaches a maximal value
Mode of action
Most accepted theory
Aspartame
Chemically, L-aspartyl-L-phenylalanine methyl ester
Provides 4 kcal/g
Since it is 200 times more sweeter than table sugar
Only a minute quantity is consumed resulting in a negligible calorie contribution
Discovery of aspartame
While working on anti-ulcer compound licked his finger
James schlatter
Used in almost all food categories but the major consumption is in beverages
Synthesis of aspartame
Aspartame metabolites
Saccharin
Chemically, 1,2-benzoisothiazol-3(2H)-on-1,1-dioxide
Sparingly soluble in water Used as Na and Ca salt
Does not provide a clean sweet taste, a bitter or metallic off taste is detected
Discovery of saccharin
Working on making food preservatives from cenal tar
Fahlberg spilled a bit of a sample on his hand, and observed an exraordinary sweetness
Synthesis of saccharin
Application of saccharin
Chemical stability
Low cost
Suitabe for use
Toothpaste mouthwashes pharmaceuticals
Food beverages
Safety concerns with saccharin
Excreted from man with little absorption
Associated with bladder cancer in rats
Still debated
Acesulfame-K
Member of dihydro-oxathiazinone dioxide class
Highly stable, crystalline sweetener Stable to hydrolysis even in highly acidic beverages
High water solubility
Discovered by Clauss and Jensen in 1970
Acesulfame-K(Ace-K)
One of the most important intense sugar
Perceived quickly without any unpleasant delay (in comparison to aspartame)at moderate sweetness level
Metabolites of acesulfame-K
Applications of acesulfame-K
Excreted completely and rapidly unchanged in the urine
Non-caloric sweetener
Used in Low-calorie and calorie-reduced beverages
Blended with other sweeteners benefits beverages especially from synergistic sweetness enhancement and quality improvement
Cyclamate
Bitter off taste, but has good sweetness synergy with saccharin
Stable over a wide range of pH and temperature
Synthesis of cyclamate
Metabolites of cyclamate
Degradation
cyclolexylamine in intestine
Chromosomal damage in animals and tumors in rats
Sucralose
Trichloro disaccharide non-nutritive sweetener
Used in canada, australia and recently approved in USA
Discovery of sucralose
Pleasant sweet taste
Hydrophilic in nature
However, discolorization and HCl liberation take place at High temperature
Alitame
Outlook of artificial sweetener
Companies are still actively pursuing the search for, and development of new non-nutritive
synthetic sweetener
Cost effective
Improved properties
Viable process for commercial production
Vitamin E
Vitamin E, more specifically tocopherol found in plant and animal oil is necessary complement of antioxidants
The lipids on the surface of cereal food are easily oxidized and emit an unpleasant odour
Universal stabilizer in oxidation process
(III) and (IV) are stable intermediates
Autoxidation radical chains are shortened
Structure of carotenoids
Composed of isoprene units joined head to tail to form a long series of conjugated double bonds
$ \beta $-carotene
Distinct
Molecular shape
Chemical Reactivity
Light absorbing properties
Food Colorants
Greater the number of conjugated double bonds
The absorption bands will be shifted To the region of longer wavelength
Ten conjugated double bonds
Eleven conjugated double bonds
Anthocyanin
Cleansing agents
Natural or synthetic substances that are used to assist the cleaning process i.e. remove dirt or dust
Natural Cleansing agent
Synthetic Cleansing agent
Soaps
Improve the cleansing properties of water
Most commonly, used in bathing or washing
Help in removal of fats which bind other material to the fabric or skin
Chemically, soaps are sodium or potassium salts of long fatty acids
Preparation of soaps
Types of soaps
Transparent soaps
Toilet soaps
Medicated soaps
Shaving soaps
Laundry soaps
Scouring soaps
Cleansing action of soaps
Limitations of soaps
Not suitable for washing clothes in hard water
Hard water contains Ca and Mg ions
Detergents
Stronger cleansing action than soaps
Works well both in soft and hard water
Do not decompose even in acidic water
Composition and Classification
Composition
Anionic detergents
Cationic detergents
Non-ionic detergents
1. Alkyl hydrogent sulphate
2. Alkyl benzene sulphonate
Aspects of anionic detergents
Cheap to manufacture
Petroleum industry provide base raw material
Very efficient in cleansing action
Commonly used in household works
Quarternary ammonium salts of amines with acetates, chlorides or bromides as anions
Cedyltrimethyl ammonium bromide
Long hydrocarbon part possess positive charge
Cationic Detergents
Aspects of cationic detergents
Poor detergency
Used for germicides Fabric softeners and specialist emulsifiers
Expensive
Non-ionic Detergents
Do not contain any ion in their constitution
Condensation Reaction
Aspects of non-ionic detergents
Enormous and permutation endless
Biggest group of detergents
Liquid-diswashing detergents are non-ionic type
Cleansing action of detergents
Mechanism of cleansing action of detergent is similar as that of soaps
In hard water
Disadvantages of detergents
Non-biodegradable
Harmful to skin
Produce stable and harmful foams in river
Soil pollution
Danger to aquatic life
Water pollution
Summary
Food additives type
Antiovidants
Cleaning agents type
Thank you