Food, by nature, is perishable. Without intervention, foods fall victim to the forces of nature, namely bacteria, yeast, and fungus, and begin to degrade. The effects of food spoilage are not only unappetizing, but the agents of spoilage can also cause foodborne illnesses or even death.
For thousands of years, humans have been using diverse methods to prolong the freshness and safety of their food to stabilize a food supply.
While some of these methods are relatively new, many of them date back to early times. We may have refined the processes and come to better understand the mechanisms, but the basic concepts stay the same today.
Here are a few of the most usual ways to preserve food:
Freezing reduces the temperature of the food so that microorganisms can't develop. Enzyme activity is slowed down, but not completely stopped during freezing.
Even though food will freeze at a temperature of 32°F, you really should keep your freezer set to 0°F or less. The reason is low-temperature microbes will still develop below 32°F, and stall at 0°F or below, affecting freezer food storage.
In the past, the arrival of fall meant a scramble to harvest and preserve as much food as possible before the cold weather set in. Most families would spend many long hours working on this enormous task because their year-round access to food was dependent on it. Only in recent decades have we become reliant on the convenience of refrigerators, which are wonderful for keeping food fresh until the power goes out.
Drying, arguably the oldest food preservation method, is a great way of preserving herbs, fruits, vegetables, and meats. Since the beginning of time, people have used the sun and nature as a preservation technique for removing moisture.
Vacuum packing makes bags and bottles airtight. This is usually used for dry fruit. Since there is no oxygen in the created vacuum, bacteria die.
Sealing is a process of covering food to keep out air, which delays but does not stop the activity of spoilage organisms. It is used essentially as a corresponding process to other procedures, such as drying or freezing. Both fat sealing and vacuum sealing methods are relatively effortless. Vacuum sealing uses a relatively economical small appliance.
Dehydrating most microorganisms also requires moisture to grow, so removing the moisture from food is a very effective method of preservation. The key to dehydration is to complete the process faster than the spoilage occurs. Evaporation is usually accelerated with the addition of average heat, sometimes provided by natural sunlight.
Immersion in Alcohol - Many foods can be immersed in alcohol to preserve them. Herbs and fruits are immersed in alcohol to create extracts. You can make a mint, vanilla, and lemon extracts this way. Your summer fruit can also be preserved in alcohol for summer baking.
Salting is a variation of drying, but typically does not remove moisture entirely, as in the case of drying. High levels of salt make for an undesirable environment for microbial growth, hence its use as a preservative. Because such large amounts of salt are needed for this technique, the results will subsequently taste very salty. Meats, like salami or prosciutto, use salting as part of the curing process. Other types of salt-cured foods are anchovies and olives.
Hanging - To use the hang-drying method, which is best for herbs, tie the herbs in bunches and hang them from an area of your house that is dry and gets a lot of airflows. After a few days, the leaves of your herbs will become brittle, and you can scrape them off the stems and store them in spice containers.
Many of these methods have been used for centuries and perfected over time. There are countless resources available, should you wish to delve more deeply into any one of them, both online and in cookbooks.