Washing It All Down: The Chemistry of Drinks

As human being which comprises of 60% of water, liquid consumption is important to fulfill the nutrition as well for pleasure. In this section we will try to see the chemistry inside of our daily drinks. Since there are a lot of type of drinks or beverage in our daily life, we only discuss 3 types; Coca Cola, tea and coffee, and wine.

The drinks

Coca Cola

Coca Cola was invented by John Pemberton and he worked on a beverage which intended to stop headaches and calm nervousness, but it was also claimed to relieve pain. He created the drink in a brass kettle in his backyard on 8 May 1886 and it was named Coca Cola from the coca leaves and kola nuts.

From left to right: Coca leaf, John Stith Pemberton, and kola nut

Pemberton was plagued by his morphine addiction and took his cocawine and soda to control the addiction. However, both beverages contained coca leaves, which in turn contains cocaine.

Cocaine

Because of the legislation, cocaine was removed from Coca Cola in 1904. Other ingredients in Coca Cola include sugar, caramel, caffeine, phosphoric acid, lime extract, vanilla, and glycerine. Besides that, it also contain the "secret ingredient" which is called Merchandise 7X and sugar is used to sweeten it (corn syrup has been used in the US).

Ira Remsen

Coca Cola is also produced which is known as Diet Coca Cola (Diet Coke). It was launched in 1982 and originally contained the artificial sweetener saccharin. Saccharin is the oldest artificial sweetener and it was discovered in 1879 by Ira Remsen (Founder of the American Chemical Society journal after dinner party). It is 300 time more sweet that sucrose but has a bitter, metallic aftertaste. The synthesis of saccharin is shown below.

Saccharin synthesis

Saccharin passes through the body unchanged (unmetabolised), so it is useful for diabetic patients. However, there are concerns over its safety about bladder cancer that have decreased its use.

Besides saccharin, aspartame can be used as well for sweetener. Aspartame was discovered by James M. Schlatter, a chemist working for G.D. Searle & Company in 1965. He made it while producing anti-ulcer drug candidate and discovered its sweetness by accidentally licking his finger (another chemistry invention by accident).

James M. Schlatter and aspartame

It is 300 times more sweet than sucrose, and it has a slower onset and lasts longer. Besides that, it is also not table for cooking and has calorific value. Moreover, the amino acid phenylamine can be a proble for those born with phenylketonuria.

Another sweetener which is commonly used is sucralose (splenda). It is 300 - 1 000 times as sweet as as sucrose and is stable enough to be used for baking and it sold $212 million in 2006 in the US alone. Sucralose was discovered in 1976 by Leslie Hough and Shashikant Phadnis and Phadnis was told to test the powder, but thought that Hough asked him to taste it. He found the compound to be very sweet and (as made longer the list of chemistry inventions by accident).

Sucralose (left) and sucrose (right)

Although there are some concerns over its safety, many are unfounded.

Besides sweetener, Coca Cola contains caffeine as well. Caffeine is an alkaloid that acts as a stimulant in humans and it is found in over 60 plants. It is suggested to act as a natural pesticides. In metabolism, caffeine is converted in the liver to the other metabolites which are:

Main metabolites conversion of caffeine

• Paraxanthine (84%) - encourage lipolysis
• Theophyline (4%) - relaxes smooth muscles - used to treat asthma
• Theobromine (12%) - dilates blood vessels and increases urine volume. It is also found in chocolate.

Tea and Coffee

Camellia sinesis - tea (left) and Coffea arabica - coffee (right)

Camellia sinensis is an evergreen plant and grows in tropical to sub-tropical climates and it needs at least 50 inches of rainfall a year and many high quality tea plants grow at elevations of up to 5 000 feet (1 524 metres). Tea contains up to 30% dry weight of catechins, and theanine and caffeine at about 3% of its dry weight (30 mg and 90 mg per cup). Tea also contains small amounts of theobromine and theophylline. For coffee, there are 2 mains species of the coffee plant, but the best is thought to be Coffea arabica. Coffee production reaches approximately 7 million tonnes annually by 2010.

Tea (left) and coffee harvesting in Indonesia

One of the compounds in tea or coffee is chlorogenic acid. Chlorogenic acid is an ester of caffeic acid and quinic acid and is a major phenolic compound in coffee. It has functions as an antioxidant and to slow the release of glucose into the blood stream after a meal. Moreover, caffeine counteracts this effect, so diabetic patients are suggested to drink decaf coffee.

Chlorogenic acid

Secondly is catechin and epicatechin are commonly found in tea and can reduce the risk of 4 of the major health problems (stroke, heart failure, cancer, and diabetes), Catechin and epicatechin are described as epimers, differing in configuration of only one stereogenic centre.

Wine

Wine also contain catechin and the red colour of wine is due to pigments called anthocyanins. Moreover, the most important in wine is malvidin which is an antioxidants and as well the anthocyanins.

Besides that, red wines also contain resveratrol about 03. mg per glass. This compound has important biological effects, in particular in inhibiting the COX enzymes and as well for cardioprotective effects. Moreover, COX enzymes are responsible for inflamation.

Some say resveratrol in red wine can increase the life expectancy (in another words the elixir of eternal life). More detail how this might work, have a look on this video below (taken from James May Things You Need to Know - About Chemistry)