Category Chemistry

HOW DOES FERMENTATION PRODUCE ALCOHOL?

Fermentation is a natural process that uses a kind of fungus called yeast. When given the right conditions of warmth and moisture, yeast will digest sugars in fruit or other plant materials and give off carbon dioxide gas and alcohol. Fermentation is used on a huge scale to make alcoholic drinks and ethanol for use in industry.

Alcoholic fermentation is the best known of the fermentation processes, and is involved in several important transformation, stabilization, and conservation processes for sugar-rich substrates, such as fruit, and fruit and vegetable juices. Alcoholic fermentation is carried out by yeasts and some other fungi and bacteria. The first step of the alcoholic fermentation pathway involves pyruvate, which is formed by yeast via the EMP pathway, while it is obtained through the ED pathway in the case of Zymomonas (bacteria). In the following step, the pyruvate is decarboxylated to acetaldehyde in a reaction that is catalyzed by the enzyme pyruvate decarboxylase.

Alcoholic fermentation is a biotechnological process accomplished by yeast, some kinds of bacteria, or a few other microorganisms to convert sugars into ethyl alcohol and carbon dioxide. In this fermentation process, yeast is mostly used as a bio-culture and aqueous solution of monosaccharide (raw materials) as the culture media for the production of beverages. In the alcoholic fermentation process, yeast generally carries out the aerobic fermentation process, but it may also ferment the raw materials under anaerobic conditions. In the absence of oxygen, alcoholic fermentation occurs in the cytosol of yeast. Alcoholic fermentation begins with the breakdown of sugars by yeasts to form pyruvate molecules, which is also known as glycolysis. Glycolysis of a glucose molecule produces two molecules of pyruvic acid. The two molecules of pyruvic acid are then reduced to two molecules of ethanol and 2CO2.

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WHAT IS ALCOHOL?

Alcohol is an organic compound. That means that it is one of the substances studied in a whole branch of chemistry called organic chemistry. Organic chemistry concerns carbon compounds, many of which are made by living (organic) things. Alcohol is a compound of carbon, oxygen and hydrogen. There are many kinds of alcohol, with different properties and uses in industry. Ethanol and glycerol are both useful forms of alcohol.

Alcohol is formed when yeast ferments (breaks down without oxygen) the sugars in different food. For example, wine is made from the sugar in grapes, beer from the sugar in malted barley (a type of grain), cider from the sugar in apples, vodka from the sugar in potatoes, beets or other plants.

Alcohol is classed as a ‘sedative hypnotic’ drug, which means it acts to depress the central nervous system at high doses. At lower doses, alcohol can act as a stimulant, inducing feelings of euphoria and talkativeness, but drinking too much alcohol at one session can lead to drowsiness, respiratory depression (where breathing becomes slow, shallow or stops entirely), coma or even death.

As well as its acute and potentially lethal sedative effect at high doses, alcohol has effects on every organ in the body and these effects depend on the blood alcohol concentration (BAC) over time.

It is classed as a depressant, meaning that it slows down vital functions—resulting in slurred speech, unsteady movement, disturbed perceptions and an inability to react quickly. As for how it affects the mind, it is best understood as a drug that reduces a person’s ability to think rationally and distorts his or her judgment.

Although classified as a depressant, the amount of alcohol consumed determines the type of effect. Most people drink for the stimulant effect, such as a beer or glass of wine taken to “loosen up.” But if a person consumes more than the body can handle, they then experience alcohol’s depressant effect. They start to feel “stupid” or lose coordination and control.

Alcohol overdose causes even more severe depressant effects (inability to feel pain, toxicity where the body vomits the poison, and finally unconsciousness or, worse, coma or death from severe toxic overdose). These reactions depend on how much is consumed and how quickly.

There are different kinds of alcohol. Ethyl alcohol (ethanol), the only alcohol used in beverages, is produced by the fermentation of grains and fruits. Fermenting is a chemical process whereby yeast acts upon certain ingredients in the food, creating alcohol.

Fermented drinks, such as beer and wine, contain from 2% alcohol to 20% alcohol. Distilled drinks, or liquor, contain from 40% to 50% or more alcohol.

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WHICH ARE VARIOUS GEMS DEPOSITS ON EARTH?

Diamond mines produce both gem-quality and industrial diamonds. Although most of the diamonds sold are industrial diamonds, the value of the gem diamond trade is much greater. Africa is the richest continent for diamond mining, accounting for around 49 per cent of world production. Artificial diamonds are made for use in industry. Most artificial diamonds are made in the United States.

A total of only 314 tonnes of diamond has ever been mined in the whole history of diamond mining. The world’s total of all gems, industrial, natural and synthetic is around 57 tonnes per year.

The world’s famous diamonds

The Star of Africa is the world’s largest cut diamond. It was cut from the biggest diamond ever found and is included in the British Crown Jewels. The Smithsonian pink diamond, although small, is extremely valuable because of its unusual colour.

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HOW DO WE WEIGHT AND CHECK THE HARDNESS OF GEMSTONES?

Weighing gemstones

Diamonds and other gemstones are weighed in a special unit. This is called a ‘carat’. There are five carats (cts) in one gramme. Therefore 1 kg is 5,000 cts. Tiny diamonds have their own measure. They are weighed in ‘points’. One carat is 100 points, so a quarter-carat gem (0.25 ct) is a ‘twenty-five pointer’. Gold is also measure in carats but these are not based on weight. They are amounts of gold in metal, and 24 carats is equivalent to 100 per cent pure gold.

Testing for hardness

By comparing other stones with the hardness of a diamond, a test called the ‘hardness test’ was developed. Minerals can be tested by measuring their hardness. In the diagram, the hardness value of several different substances is given. This is called the Mohs scale and measures hardness from one, representing talc, to ten — diamond — with the highest hardness value.

Calcite is a colourless mineral found in limestone; gypsum is a white mineral and is used for making plaster.

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DO GEMSTONES PLAY ANY ROLE IN ENVIRONMENT CONVERSATION?

Gemstones play an important part in our lives. We use gems in medicine, space travel, weather forecasting, and engineering in industry. Without them we would not be able to drill into the Earth’s crust to extract oil, which has numerous uses in today’s world. However, the extraction of gemstones can cause a number of environmental problems.

Wildlife

During the mining process, large areas of vegetation are cleared to allow for the exploration of the area, the actual mining and the processing of the gemstones retrieved from the mine. As a result, the animals and plants in the area are wiped out.

Pollution

The heavy digging and lifting machines used in the mining industry pump out carbon monoxide, hydrogen and oxides of nitrogen and sulphur. These can be harmful to humans and wildlife. The carbon monoxide is converted into carbon dioxide in the atmosphere. This contributes to the greenhouse effect — global warming — which could devastate our planet if it is not controlled.

Waste

Usually, a lump of rock bigger than a house must be crushed and sorted to find one small gem. This waste must be disposed of safely so that it does not cause further damage to wildlife. The crushing of waste rock also produces a lot of dust, which can hang in the air, making breathing uncomfortable. Water drainage from mining processes carries acidic waste products into rivers, causing harm to the local ecosystem.

Rarity

Many gems are rare. Even gems that are thought of as common, such as amethyst, are rare compared to most rocks in the Earth’s crust. To conserve these rare stones, scientists have found ways of creating artificial gemstones, mainly for use in industry.

The future

To protect the environment from damage caused by gemstone mining, it must be managed properly. This means that governments and mining companies must stick to rules that encourage waste to be disposed of safely. They must also limit destruction of ecologically important areas, such as habitats that contain endangered species of plant or animal life.

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HOW GEMS ARE USED IN SPACE SCIENCES AND IN THE FIELD OF MEDICINE?

 

Gems have played an important part in medicine since around the 1960s. Rubies are used to produce a laser beam in certain types of lasers. Ruby lasers are used in the removal of skin blemishes, such as tattoos. However, there can be side-effects to this treatment, such as scarring and a removal of natural skin colour in the area.

Diamond has many special properties. Hard diamond chips are used on dental drills to allow them to cut easily through teeth. Many kinds of radiation can travel easily through diamond and it can withstand huge pressures. This makes it suitable for use in space, and in weather and spy satellites. Perfect diamonds are used on space probes, as they are unlikely to be damaged by the deadly gases found on some planets, such as Venus.

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