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Timeline of Food Preservation Methods

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Steve Sutton

on 29 April 2014

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Transcript of Timeline of Food Preservation Methods

~500,000 BC - Fire Cooking
Timeline of Food Preservation Methods
Stephen Sutton
12,000 BC - Sun Drying
600 AD - Jam
1400 AD - Curing
1784 AD - Refrigeration
1809 AD - Canning
1871 AD - Pasteurization
1945 AD - Vacuum Packing
2000+ AD - Chemical Preservatives
There are several theories as to why
Homo Sapiens
and
Homo Erectus
began to cook food. Many point to the fact that cooking food over a fire killed bacteria in the meat, improved taste, and more importantly, broke down the protein and muscle fiber within the meat in order to be digested more efficiently by the species newly evolved and more efficient intestine.
Sun drying began to be used in arid climates around 12,000BC. Humans left many types of food items in the sun (fruits, vegetables, meat) to dry out in order to be consumed or stored. By sun drying food items, the heat from the sun heats and causes the water within the food to evaporate. With a lack of water present, the growth of bacteria on food is greatly inhibited.
Although the international origin of the jam making process is not entirely known, the process of making jam was implemented by merchants in order to get the most out of their stock. As the fruits they sold began to rot, they would pulverize and extract the juice from sour fruits (oranges, limes, lemons) and boil down the juice/pulp mixture. After a period of boiling and adding sugar, the pectin present in the fruit juice becomes viscous and jelly like, which resulted in a spreadable fruit concoction. In the modern day, gelatin is added to jam as a pectin replacement which also gives the product a better texture.
Curing was discovered around 1400. The original curing process involved surrounding cuts of meat in sea salt or table salt (sodium chloride). This dried out the meat by creating a solute rich environment which extracted water from the meat and any bacteria or microorganisms within it, effectively sterilizing the meat. If meat is left out, it begins to oxidize, causing it to become rancid and inedible, the salt also acts to slow the oxidation process, preventing the meat from going rancid.

Sodium nitrate was also found to be a good additive in the meat. It kills bacteria and gives meat a more appealing, red color.
Canning involves the process of storing food in sterilized jars or cans, which have a negative oxygen pressure inside. Food is added to a jar and heated to high temperatures, at this high temperature, any oxygen and molecules within the jar have expanded and the lid is quickly added. As the jar/can cools, the molecules become less agitated and a low pressure (of oxygen) becomes present in the container. This low pressure stops the growth of microorganisms by cutting off the oxygen supply required for bacteria to grow.
Vacuum packing is a similar idea to canning, except food is packed into malleable (plastic) bags, and a machine or person extracts the air with great force, causing a lack, if not 0 amount of oxygen within the bag. With this lack of oxygen, microorganisms cannot grow and thrive in the food.
Refrigeration is a large topic to cover, as it spans from the early practice of storing food outside in the winter, to using electricity and magnetism to transfer heat between chemicals.

Early forms of refrigeration included the creation of small sheds or holes in the ground. Butchers or residents would wrap cuts of meat and bury or surround them in ice and snow. This froze the meat and inhibited the growth of organisms and prevented the meat from turning rancid.

Modern household refrigerators follow the 2nd law of thermodynamics. In a "vapour compression cycle", freon is compressed as a vapour, heating it up, and slowly cooled again. The freon then passes through a valve which causes a sudden decrease in pressure, cooling it drastically. This cooled freon is passed through a radiator where cool air is harvested and vented into the refrigerator.
Pasteurization, usually associated with milk, is the process of rapidly heating and cooling food to stunt the growth of harmful bacteria. The pasteurization process is not meant to completely sterilize food, but only to reduce the amount of possibly harmful bacteria present. Pasteurization is not commonly used outside of dairy products as it often cooks or ruins the taste and quality of the food.
There are a wide range of chemicals used in the preservation of food. The aim of chemical preservatives is to stop microbial growth, retain flavor and texture and/or prevent unwanted chemical changes in food (oxidization). A very commonly known chemical preservative is vinegar. Vinegar is used in a process is called pickling, in which food items are submerged in vinegar which begins to replace the water within vegetables or eggs with the vinegar. This creates a harsh environment for bacteria to grow and effectively sterilizes the product. Alcohol is a more powerful preservative and is usually used to protect scientific artifacts or samples.
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