Chemistry and Food Preservation....

The impact of chemistry in our every day living extends even to methods and ways of food preservation. Common methods of food preservation include: salting, cooking, drying, refrigeration and freezing, canning, irradiation, dehydration, use of spices, pickling, pasteurizing, fermentation, and lots more. The aim and target of these methods is to create an unfavorable environment for microbes that cause food spoilage. In certain cases, the technique used may destroy enzymes naturally found in food that causes food spoilage.

To further demonstrate the role of chemistry in food preservation, lets take a look at food preservation methods such as pickling, fermentation and the use of spices.

Pickling: Pickling is a method of preserving food in an edible anti-microbial liquid. Vinegar is used to pickle other foods. Food is placed in an edible liquid that inhibits or kills bacteria and other micro-organisms. pickling agents include brine, vinegar, alcohol and vegetable oils. Many chemical pickling processes also involve heating or boiling so that the food being preserved becomes saturated with the pickling agent.



Use of spices: Allicin present in garlic acts as an antimicrobial agent as does the allyl isothiocyanate present in mustard. Thymol, present in thyme, oregano and sage also has antimicrobial properties. Spices contain essential oils with antimicrobial properties. Many of these oils are derived from the organic compound Phenol. This molecule is used as an antiseptic and disinfectant. Another molecule Eugenol, also an essential oil found in cloves, sage, and cinnamon also have antimicrobial properties.

Fermentation: Yest is added to grape juice, and they digest the sugars in the grape forming the byprouct alcohol. Alcohol kills microbes that causes food spoilage. When alcohol is exposed to air, the bacteria Acetobacter begins to grow and this will convert alcohol to acetic acid (vinegar). Vinegar also can be used for food preservation.





From the above, it can be deduced that without extensive study of and the use of chemistry, food preservation methods will be limited. Therefore chemistry plays a major role in preservation chemistry.

chemistry of aspirin, an every day drug..

Basically, when we have a headache or pain in any part of our body, it is likely that we take aspirin. This drug is probably one of the most common and best known drug in the world. Aspirin is a pain killer that reduces inflammation. It also reduces or prevent the risk of a heart attack.

The major chemical component of aspirin is known as Salicin and its derivative Salicylic Acid has similar properties. The chemical structure of salicin is based on a hexagonal "Benzene ring" with two additional side groups, one of which is a hydroxyl group (-OH) and the other a carboxylic group (-COOH). Salicin and its derivative Salicylic Acid can cause horrendous digestive problems, therefore, Salicylic Acid is reacted with another chemical to change the hydroxyl group (-OH) on the benzene ring to an Acetyl group (-OCOOH) which makes it less harmfull. The chemical formed is called Acetyl salicydic Acid (ASA).

Diagramatic representation of the structure, composition and synthesis of Aspirin.


Aspirin when taken, binds to an enzyme (cylo oxygenase-2) in cells. This enzyme is produced in large quantities by damaged calls and they are responsible for pain. In the absence of ASA, this enzymes produce Prostaglandins which send messages to the brain that a part of the body is in pain. They also cause damaged cells to rlease fluid from blood and thus, become inflamed. When ASA is taken, the enzyme is no longer able to produce prostaglandins thus, messages to the brain that a part of the body is in pain is reduced and hence, the feeling of pain and also inflamation is reduced.

ASA also hinders the production of prostaglandins in the blood stream. Prostaglandins are involved in blood clotting, this is one reason why many older people take aspirin continually, to prevent blood clots in their blood stream andby so doing, reduce the risk of heart attack.

"Really, paper!"..... Never crossed my mind.

Paper, a versatile material with wide range of uses of which its most common use is for writing, printing upon and most often packaging is a product derived from pressing together moist fibres, tipically cellulose pulp derived from wood, rags or grasses, and drying them up into flexible sheets. That is to say paper is a product derived from plants.

The processes involved in paper making are chemistry based and involves processes in chemistry, implying that chemistry is part of our every day life. Paper making involves chemical pulping, or mechanical pulping, or recycling. then comes additives, drying then finishing.

CHEMICAL PULPING: The aim of chemical pulping process is to break down the chemical structure of lignin and render it soluble in the cooking liquor, so that it may be washed from the cellulose fibres. This process makes the fibre loose thus, making the pulp. This pulp can be bleached to produce white paper or dyed to produce colored paper. unbleached paper can be used directly for bags and boxes but are often processed further.

MECHANICAL PULPING: This is of two types, Thermomechanical pulp and Mechanical pulp. For thermomechanical pulp, wood is chipped and fed into a large steam-heated refiner where the chips are squeezed and fibreized between two steel discs. While for the mechanical pulp, debarked logs are fed into grinders where they are pressured against roatating stones and fibreized. Paper made from this pulp are yellow and become brittle over time.

RECYCLED PAPER: Paper recycling process may involve any of the above mentioned process. By mixing with water and applying mechanical process, the hydrogen bonds in the paper are broken and the fibres are separated again.

ADDITIVES: Besides fibres, pulp may contain fillers such as chalk, or china clay, which improve the characteristics of the paper for printing or writing.

DRYING: After the paper web is produced, pressing the sheet removes water from the pulp. Once water is forced out of the sheet, felt is used to collect the water. Drying involves using air and or heat to remove water from the paper sheet.

FINISHING: The paper may undergo sizing to alter the physical properties for various applications. Paper at this point is uncoated. The paper is then fed onto reels if it is to be used on web printing presses or cut into sheets for other purposes.

Doctor am ill....... " My drinking water? "

Sadly, in this day and age there are few if any place where water which is a necessity of life and most abundant substance on earth is safe for consumption without any form of treatment no matter how pure we think they might be. Water if not treated may contain harmful substances, microorganisms, bacteria, parasites, etc which can cause a variety of ailment.
Water is composed of two molecules of hydrogen, and a molecule of oxygen which are chemically bound together thus giving the molecular formula H2O. Water can be of solid, liquid, or gaseous form and its purest source is from rainwater though other water bodies such as oceans, rivers, lakes, etc hold large amounts of water.

The goal of all water treatment process is to remove existing contaminants in the water or reduce the concentration of such contaminants thus, making it safe for its desired end-use. These processes can be of physical process such as settling and filtration or chemical process such as disinfection and coagulation. Biological processes are also employed in the treatment of waste water and this process may include aerated lagoons, activated sludge or slow sand filters.

" note that these processes all involves the use of principles in chemistry."

Substances removed during the tretment process, range from bacteria, algae, viruses, fungi, and minerals such as iron, manganese, and sulphur. Man made chemical pollutants including fertilizers are also removed.

A combination of the following processes is used for the municipal drinking water treatment world wide;

1. PRE-CHLORINATION: Employed for algae control and arresting any biological growth.

2. AREATION: Along with pre-chlorination for the removal of dissolved iron and manganese.

3. COAGULATION: Employed for flocculation.

4. POLYELECTROLYTES: Also known as coagulant aid is employed to improve coagulation and for thick floc formation.

5. SEDIMENTATION: For solid seperation, that is, removal of suspended solids trapped in the floc.

6. FILTERATION: For removal of carried over floc.

7. DISINFECTION: For killing bacteria.

CAN THIS BE TRUE?

Sure, the involvement of chemistry in our daily life are unlimited. In fact, it starts right from when we are being given birth to and up to when we die. take for example, waking up in the morning, to the sound of an alarm. The alarm which is a common household appliance is powered by batteries which are built or manufactured on the principles of chemistry even their mode of operation.

These batteries contain a negative and a positive electrode. The positive electrode is made of carbon rods which are being surrounded by a mixture of carbon and manganese dioxide while the negative electrode are made of zinc. This setup is based on the principles of chemistry (electrolysis).

Also common household items such as detergent, household cleaners even cooking gas are all products of chemistry based on various principles in chemistry. Even when we take our bath, chemistry is involve. The soap we use is also a product of chemistry, It contains chemicals which are chemically formulated and obey the laws of chemistry governing their formation and use. Coloring agents used in the manufacture of make-up for women, nail polish, hair dye, etc are all products of chemistry even the tooth paste for brushing our teeth, insecticides, body sprays, perfumes, polythene bags etc are products of chemistry. Without understanding the chemistry of their formation, their manufacture or production and usage would be limited if not impossible.

Almost all we do and around us in our daily lives involves chemistry even the food we eat, right from its preparation up to its transformation to energy in the body is chemistry. The burning of wood for fuel or burning of petrol in a car engine is all chemistry. Chemistry is all around us no doubt.