The Biology and Chemistry of Food Preservation

(Image Credit: Vegetarian Times)

(Image Credit: MadgeTech)

November 21, 2024

Abram Tran 

12th Grade

Westminster High School 



Food Spoilage


What happens when you leave a piece of meat out overnight? Overnight, the meat will become covered in a thin layer of a slimy substance accompanied by an unpleasant odor. If someone ended up consuming the meat in this phase, they would notice the food was incredibly bitter, and after a while, they would begin to experience stomach issues.


What happened to the piece of meat was a process called spoilage. Spoilage is when harmful bacteria such as E. Coli or Salmonella, microorganisms, and mold begin to consume the nutrients in the food and then release waste chemicals around them. These chemicals in turn can cause the food to taste different, have an unpleasant odor, and often, become dangerous for human consumption.


To prevent this, techniques such as fermenting, canning, or freezing food can help prolong its shelf life and keep it safe to eat. These preservation methods work because they affect the food or the environment around the food to create an inhospitable environment that inhibits the growth of microorganisms, bacteria, and mold. There are numerous types of preservatives, all of which have their unique histories and own ways of slowing down spoilage.


Salt


Salt is one of the oldest methods of food preservation, dating back to ancient civilizations such as the Egyptians and Romans, who used it to preserve meats and fish. Salt was so highly valued for its ability to preserve foods it was even used as currency in some societies, most notably the Mali Empire which garnered immense wealth through it. Salt works by drawing moisture out of food and out of the cells of microorganisms, creating an environment that is incredibly hostile to them, and effectively inhibiting spoilage. Salt preservation is used in foods like salted fish, pickles, and cured meats such as ham and bacon, with the added benefit of a distinct taste.



Fermenting


Like salt, fermentation is an ancient technique that has been used for thousands of years by various cultures to preserve foods. Notable examples include yogurt in Central Asia, kimchi in Korea, and sauerkraut in Europe. Fermentation relies on the same process as spoilage, where bacteria consume the nutrients of the food item, but create an environment where harmful bacteria cannot survive or one where beneficial bacteria or yeast convert sugars in the food into acids or alcohol. Because of this the food changes its properties entirely and becomes a completely different substance oftening containing healthy bacteria referred to as probiotics. Common fermented foods today include yogurt, kombucha, cheese, and kimchi. These foods are prized not only for their extended shelf life but also for their health benefits, as they often contain probiotics.



Canning


Canning was developed in the early 19th century by French chef Nicolas Appert, who discovered that heating food in sealed jars could prevent spoilage despite not knowing what microorganisms or bacteria were. Canning became more widespread during the Industrial Revolution as the availability of aluminum became more common, making it easier to create more cans. Canned foods became incredibly popular for military usage as the cans both protected the food and provided an easy way to transport it. The process of canning involves heating food to kill bacteria and then sealing it in airtight containers, where the absence of air and the high temperatures create a sterile environment inside the can and prevent microorganisms from being able to reach the food in the first place. Canning today is still an incredibly popular method used to both preserve and contain foods for both civilian and military use. A variety of all sorts of foods are stored within cans from milk, fruits, soups, and meat.



Freezing


Freezing as a preservation technique can date back to 3000BC China, where meats were placed inside snow to prolong their lifespan. Modern Freezing gained popularity in the 20th century with the invention of modern refrigeration. Freezing lowers the temperature of the food to a level that significantly slows down enzyme activity and microbial growth, keeping food safe while preserving its original texture and flavor. This method however does not get rid of any of the bacteria like other methods might do, rather it just puts them in a dormant state until they are thawed out again. Often is the case that freezing is not enough to fully preserve a certain food as certain microorganisms will be able to resist the cold. The methods have become the most popular in the modern day due to easy access to technologies such as refrigerators and their ability to preserve both the taste and nutritional values of the foods.


Drying


Drying is another one of the earliest forms of food preservation, used by ancient Egyptians, Native Americans, and many other cultures. A new form of drying called freeze-drying is a modern variation used to preserve delicate foods, such as berries and coffee, with minimal loss of nutrients.


Drying removes water from food and by lowering the water content, denies bacteria the water it needs to grow, preventing spoilage and keeping food safe for longer periods. Dehydrated foods such as dried fruits, jerky, and powdered milk are modern examples of the more traditional drying process. With access to arguably more effective forms of preservation such as freezing or canning, drying foods has more or less become a process to create a luxury item, with numerous flavors of beef jerky being sold and dry-aged meat becoming a new gourmet food.



Artificial Preservatives


Artificial preservatives are synthetic chemicals added to food to extend shelf life, maintain freshness, and prevent spoilage. Common examples include Sodium Benzoate, Sorbic Acid, Sorbates, Butylated Hydroxyanisole (BHA), and Butylated Hydroxytoluene (BHT). These Artificial preservatives prevent the growth of microorganisms by creating environments with drastically different pHs, a lack of oxygen content, or slowing down chemical processes like oxidation. Artificial preservatives are essential in many processed foods, including canned soups, packaged snacks, and baked goods. Although they are incredibly useful for food preservation, research has correlated their in our food supply to major health risks such as cancer



Conclusion


Food preservation has been a cornerstone of human survival and culture. From traditional methods like salting, fermenting, and drying to modern refrigeration and artificial preservatives, each technique helps to extend food's shelf life and prevent spoilage. Today, these methods continue to be used in a manner that balances safety, flavor, and convenience in a world where maintaining speed and quality of food are king.

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