In the 19th century, the world was in the grip of a pandemic caused by bacteria. Millions died every year from diseases such as cholera and tuberculosis. Medical researchers had no idea what caused them or how to stop them from spreading.
At the start of the 19th century, Louis Pasteur was a young scientist looking for a breakthrough in the lab. He knew that microorganisms caused decay and spoilage in food and drink. But could these bacteria also be causing diseases in people too? This was the question that drove Pasteur to focus on his research.
An accidental discovery and an experiment
The first step of Pasteur's research was to prove that microorganisms were responsible for a specific disease. He decided to focus his efforts on chicken cholera, a disease that killed thousands of chickens each year. To prove his theory, Pasteur used a series of experiments. First, he infected a few chickens with the disease and kept them in the same room as other chickens that weren't infected. He found that the healthy chickens soon became sick too. Next, he moved the sick chickens to a different room and isolated them again. He found that the healthy chickens in the second room remained healthy. This showed that the disease was being transmitted through airborne droplets.
The conclusion of his experiments
Next, Pasteur wanted to prove that microorganisms were responsible for beer going bad and wine going sour. He filled two jars, one with beer and the other with wine, and put each one inside two different rooms. He left them for a few months and found that both drinks had gone sour. He then repeated the experiment with the same jars, but this time he heated the jars to kill the microorganisms first. When he left the jars for a few months again, the drinks inside were still fresh. This was a major breakthrough. Pasteur had proven that bacteria were causing food and drink to go off, and he had also found a way to stop them.
The pasteurization process
Pasteurization is a process that kills all the microorganisms in a liquid. It's named after its inventor, Louis Pasteur. It's used to kill harmful bacteria in a liquid, such as milk and apple juice. In practice, pasteurization is usually achieved by heating the liquid to a specific temperature for a specific amount of time. For example, you might heat milk to 72°C (162°F) for 30 minutes to pasteurize it. There are two main benefits of pasteurization. First, it extends the shelf life of liquids by killing microorganisms that would otherwise cause them to go bad. Second, it prevents people from getting sick from consuming contaminated liquids.
Benefits of pasteurization
- Extending shelf life - Pasteurization extends the shelf life of liquids by killing microorganisms that would otherwise cause them to go bad. This allows companies to sell the same product for longer periods, which means they can reduce costs by decreasing the frequency of purchase orders.
- Preventing foodborne diseases: Liquids that are contaminated with harmful microorganisms, such as E. coli, can cause foodborne illnesses. By pasteurizing these liquids, you can kill the microorganisms and reduce the risk of people getting sick. This is especially important when you’re dealing with liquids that are consumed by children or the elderly, who are more susceptible to foodborne illnesses.
Limitations of the pasteurization process
- Thermal degradation: During the pasteurization process, liquids will undergo a chemical reaction that changes their composition. This is known as thermal degradation and can have negative effects on the taste and smell of certain liquids, especially those with high sugar content.
- Reduction in nutrients: Some nutrients in liquids, such as vitamins, will be broken down by the pasteurization process. Therefore, the nutritional value of these liquids will be reduced.
- Disruption of proteins: Proteins in liquids are negatively affected by the pasteurization process, causing them to clump together. This can affect the taste and texture of these liquids.
Lessons learned from pasteurization
- Rapid adoption: The benefits of pasteurization were so clear that the process was rapidly adopted around the world. Today, most foods and drinks are pasteurized before they’re sold on the market.
- Increased public health: The rise of pasteurization led to an increase in public health, with fewer people getting sick from contaminated food and drink. This, in turn, led to a rise in the average life expectancy.
- Standardization of food: With fewer people getting sick, there was more demand for standardized food. This was particularly apparent in the dairy industry, where pasteurization led to the standardization of milk.
- Reduction in foodborne illnesses: Foodborne illnesses were extremely common at the start of the 20th century. However, with the rise of pasteurization, there was a significant reduction in these illnesses.
Louis Pasteur was a pioneer of the science of microbiology, whose discoveries led to the rapid adoption of the pasteurization process. This process extends the shelf life of liquids by killing microorganisms that would otherwise cause them to go bad and allows people to consume liquids without getting sick. Today, numerous industries and individuals rely on pasteurization to improve their products and lower the risk of foodborne illnesses.