Download Chemicals and Food

Chemistry around us
Chemicals are all around in our home. In the kitchen, on the shelf in the bathroom, in the garden, garage, in the first aid kit etc.
Many of them may be hazardous if used, stored or disposed of improperly. They may pose serious fire, health or environmental
hazards. If they are used, stored and disposed of properly, however, they can be relatively safe.
Common products in household
 household cleaners
abrasive cleaner
ammonia
bleach
disinfectant
carpet freshener
air freshener
window cleaner
furniture polish
oven cleaner
rug and upholstery cleaner
 garden products
fertilizers
insecticides
herbicides
 Barbecue products
propane
charcoal briquettes
lighter fluid
 Home maintenance
enamel /oil/latex/ water-based paint
varnish
paint thinner
varnish remover
drain opener
mouse/rat poison
roach and ant killer
 laundry products
laundry detergent
fabric softener
 Health and beauty products
hairspray
hair remover
fingernail polish,
fingernail polish remover
hair colouring products
medications

Automotive fluids
oil
anti-freeze
fuel
brake fluid
windshield washer fluid
autobattery
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Chemicals and Food
Cooking is just chemistry by another name. There are loads of different ways to cook food- e.g. boiling, steaming, grilling, frying,
baking.
Many foods have a better taste and textures when cooked. Some foods are easier to digest once they´re cooked (e.g. potatoes, flour)
The high temperatures involved in cooking also kill off microbes that cause disease- this is very important with meat.
Some foods are poisonous when raw and must be cooked to make them edible (e.g. red kidney beans contain a poison that´s only
destroyed by at least 10 minutes boiling)
Cooking causes chemical changes. Cooking food produces new substances. That means a chemical change has taken place. Once
cooked you can´t change it back. The cooking process is irreversible. (you can never unscramble an egg) Examples:
Eggs and meat
Eggs and meat are good sources of protein. Protein molecules change shape when you heat them. The energy from cooking breaks
some of the chemical bonds in the protein, and this allows the molecule to take a different shape. This gives the food a more edible
texture. The change is called denaturing.
Potatoes
Potatoes are a good source of carbohydrates. Potatoes are plants, so each potato cell is surrounded by a cellulose cell wall. Humans
can´t digest cellulose, so this makes it difficult to get to the contents of the cells. Cooking the potato breaks down the cell wall,
making it a lot easier to digest.
Food Additives
Processed foods often contain additives.
Humans have been adding stuff to food for years. Before fridges were invented, we added salt to meat to stop it going off. Now we
use additives not just to preserve food, but to make it look or taste different.
Food manufacturers add various chemical compounds to food to improve its appearance and taste. These additives must be listed in
the ingredients list on the back of the packet. Most additives have E-numbers- e.g. E127 is erythrosine ( a red dye) and E201 is
sodium sorbate (a preservative) Additives with E-numbers have passed safety tests and can be used in Europe.
1. Preservatives help food stay fresh. Without them, more food would go off and need
throwing away.
2. Some foods „go off“ after reacting with oxygen- e.g. butter goes rancid.
Antioxidants are added to foods that contain fat or oil to stop them reacting with oxygen.
3. Colourings and flavourings make food look and taste better. There are five basic flavours- sweet, sour, bitter, salt and
savoury.
4. Emulsifiers and stabilisers stop emulsions like mayonnaise, low-fat spread and ice cream from separating out.
5. Sweeteners can replace sugar in some processed foods- helpful to diabetics and dieters.
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There are natural and synthetic additives.
Some food additives are of natural origin, e.g.lecithin from soya beans. Some synthetic additives are identical to natural substances.
Others are completely new synthetic substances.
Some people think that some synthetic food colourings make children hyperactive. But many scientific studies haven´t found any
connection between additives and hyperactivity at all.
A small number of people are allergic to some additives.
Some additives aren´t suitable for vegetarians. For example, the food colouring cochineal comes from crushed insects. And gelatin
from animal bones is used to thicken and set some foods.
Additives can be detected in a wide range of chemical techniques. For example you can use paper chromatography to investigate the
composition of food colourings. This technique separates different compounds based on how well they dissolve in a particular solvent.
Ethanol
There are different kinds of alcohol, but the one that´s in beer, wine and so on is ethanol.
Ethanol can be made by fermentation. Fermantation is the process of using yeast to convert sugars into ethanol. Carbon dioxide is
also produced. The yeast cells contain an enzyme called zymase. Fermentation happens fastest at a temperature of about 30°C. At
lower temperatures, the reaction slows down. If it´s too hot the enzyme in the yeast is destroyed. It´s important to prevent oxygen
getting to the fermentation process. If oxygen is present, a different reaction happens and you don´t get ethanol. When the
concentration of alcohol reaches about 10 to 20°C, the fermentation reaction stops, because the yeast gets kiled off by the alcohol.
Different types of alcoholic drinks are made using sugars from different sources- usually from grains, fruits or vegetables, e.g.
barley is used to make beer and grapes are used for making wine.
The fermentation mixture can be distilled to produce more concentrated alcohol. Brandy is distilled from wine, whisky is distilled
from fermented grain and vodka from fermented grain or potatoes.
Perfumes
Chemicals that smell nice are used as perfumes and air fresheners. Esters are often used as perfumes as they usually smell quite
pleasant. Esters are pretty common in nature. Loads of common smells contain natural esters. Esters are also manufactured
synthetically to enhance food flavours or aromas, e.g. there are esters that smell of rum, apple, pineapple. Esters are made by
esterification. An example is heating a carboxylic acid with an alcohol.
Commonly used medicines are those you can buy without a prescription. They fall into the following categories:
antacids (neutralize the acid in your stomach), laxatives (relieve constipation), antidiarrheals (balance the way fluids move through
intestines), vitamins and minerals (we often lack them though we should ideally get them from a balanced diet), antihistamines
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(relieve or prevent allergy symptoms), pain relievers/ pain killers (are helpful in treating many types of pain, such as from arthritis,
earache, back pain, pain after surgery, from the flu or a cold, headache, toothache...), ointments, vitamins, ...
Common drugs prescribed doctors: antibiotics
Plastics used in our homes /gardens
Pete bottles, insulators, teflon pans, wall papers, floor covering, ropes, thermal underware, carpets, buckets, hosepipes, acquariums,
foam for packaging, sockets, rubber boots, etc.
A detergent is a surfactant (=saponát) or a mixture of surfactants having "cleaning properties in dilute solutions." Soaps are
surfactants and detergents. Most commonly, detergent refers to alkylbenzenesulfonates, which are similar to soap but are less
affected by "hard water." In most household contexts, the term detergent by itself refers specifically to laundry detergent or dish
detergent, vs hand soap or other types of cleaning agents. Detergents are commonly delivered as powders or liquids.
Laundry detergent. One of the largest applications of detergents is for cleaning clothing. The formulations are complex, reflecting
the diverse demands of the application and the highly competitive consumer market. In general, laundry detergents contain water
softeners, surfactants, bleach, enzymes, brighteners, fragrances, and many other agents. The formulation is strongly affected by the
temperature of the cleaning water, and of course varies from country to country.
Gasoline, or petrol, is a petroleum-derived liquid mixture which is primarily used as a fuel in internal combustion engines. It is also
used as a solvent, mainly known for its ability to dilute paints. It consists mostly of aliphatic hydrocarbons obtained by the fractional
distillation of petroleum, enhanced with iso-octane or the aromatic hydrocarbons toluene and benzene to increase its octane rating.
Small quantities of various additives are common, for purposes such as tuning engine performance or reducing harmful exhaust
emissions. Some mixtures also contain significant quantities of ethanol as a partial alternative fuel. In North America, the substance
is called gasoline, a term often shortened to gas.
A Chemistry of Love
There are not any magic love potions that you can use to make someone fall in love, but chemistry does play an important role in how a
relationship progresses. First, there's attraction. Nonverbal communication plays a big part in initial attraction and some of this
communication may involve pheromones, a form of chemical communication. Did you know that raw lust is characterized by high levels
of testosterone? The sweaty palms and pounding heart of infatuation are caused by higher than normal levels of norepinepherine.
Meanwhile, the 'high' of being in love is due to a rush of phenylethylamine and dopamine. All is not lost once the honeymoon is over.
Lasting love confers chemical benefits in the form of stabilized production of serotonin and oxytocin. Can infidelity be blamed on
chemistry? Perhaps in part. Researchers have found that suppression of vasopressin can cause males to abandon their love nest and
seek new mates.
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