How Did Germ Theory Change Preservation?
- Ester Lilaj
- Jun 29
- 2 min read
For millions of people across the globe, it is difficult to imagine a world where food spoilage and foodborne illnesses were accepted as unavoidable parts of life. A carton of milk had no expiration date, and there was no process of pasteurization to eliminate harmful microorganisms. Today, many of us rarely worry about getting sick from what we consume thanks to chemical preservatives, food safety regulations, and scientific preservation techniques. Many of these advancements can be traced back to germ theory, one of the most revolutionary scientific discoveries in history. But what exactly is germ theory and what role has it played in the way we preserve our foods and beverages?
For centuries, people believed illnesses and spoilage arose spontaneously, or were caused by ‘bad air’. So, when French chemist Louis Pasteur presented his germ theory of fermentation in 1857, it challenged the long-held beliefs about spoilage and disease. Pasteur was able to prove that microorganisms – not spontaneous chemical reactions – were responsible for fermentation and decay.
Pasteur’s discoveries fundamentally transformed the way food scientists and manufacturers approached food preservation. The focus of food preservation became a question of controlling the microbes responsible for spoilage and illness, which led to the rise of modern food preservation techniques in use today.
One of the most well known developments is pasteurization, named after Pasteur himself, which involves heating food and beverages to temperatures high enough to kill microorganisms, but not so high that the heating spoils flavor or diminishes nutritional qualities. Although it was originally developed to preserve alcoholic beverages, pasteurization has evolved to become fit for preserving milk, which has prevented outbreaks of diseases like tuberculosis.
Beyond pasteurization, germ theory has influenced the development of multiple methods of food and beverage preservation. Chemical preservatives like sodium benzoate and potassium sorbate target the inhibition of specific microbes, a direct contribution of the idea that microbes are responsible for spoilage. Refrigeration became popular because of the later discovery that lower temperatures reduce microbial metabolism. The techniques of salting and sugaring make microbial growth difficult by limiting water availability. Preservation has become a matter of targeted specificity rather than random success by learning the variety of microorganisms that cause food spoilage and illness.
Today, preservation remains grounded in germ theory. New developments in shelf-life testing, sanitation standards, and hazard analysis are all built upon the understanding that microorganisms hinder the safety and quality of food. Whether it is the pasteurization of milk or the refrigeration of produce, many of the techniques consumers take for granted are attributed to germ theory, allowing our food system to become safer, more reliable, and capable of feeding billions.
Ester Lilaj is a rising junior at McLean High School in McLean, Virginia. She volunteers at various food banks in her area, helping organize inventory and serving members of the community. She is interested in food safety and preservation.
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