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Science

Food and drink

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Beer and wine are alcoholic drinks made by fermentation reactions that use yeast to convert sugars into ethanol. There are harmful effects and social problems because of ethanol in drinks.

Intelligent packaging keeps food fresh by removing water from the food, or stopping it reacting with oxygen.

Emulsifiers have a 'water-loving' head and a 'water-hating' tail. These substances allow oil and water to mix so they can become emulsions such as mayonnaise.

Making beer and wine

Ethanol

Ethanol is the type of alcohol found in alcoholic drinks such as wine and beer.

Structure of ethanol

formula	chemical structure	ball-and-stick model
C₂H₅OH

Sugar from plant material is converted into ethanol and carbon dioxide by fermentation. The enzymes found in single-celled fungi - yeast - are the natural catalysts that can make this process happen. Here are the word and balanced formulae equations:

sugar → ethanol + carbon dioxide

C₆H₁₂O₆ 2C₂H₅OH + 2CO₂

Fermentation usually works best at around 37ºC. It is a slow process and several weeks or more are usually needed to produce an acceptable alcoholic drink.

Beer

The sugars for beer-making come from boiling barley in water. Hops are added to adjust the flavour of the beer.

Wine

The sugars for wine-making come from grape juice. Different varieties of grapes are used to produce wines with different flavours. Wine contains a higher proportion of ethanol than beer does, because grape juice contains a higher concentration of sugars than barley in water.

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