In this time of quarantine, food preservation plays a huge role in order to prolong fresh foods and lessen the need to go outside and buy food.
As a kid, I remember walking into my grandmother’s pantry and being enthralled by all of the goodies that were inside. Garlic heads tied in old nylons, wooden barrels filled with onions and potatoes and turnips. Rows and rows of jars of bread and butter pickles, choke-cherry jam, blueberry jelly, pickled eggs, and many other impressive collections of preserves.
My grandmother lived on a homestead, and these preserves were completely necessary if the family wanted to eat something other than oatmeal for the entire season. To this day, I have never tasted a better pickle than the ones that came from her pantry, and one afternoon she granted me the honor of sharing her process with me.
That teaching inspired me to look into methods of preservation other than pickling and led me to all of the information that you’re about to read. This is a practice that could be incorporated into any household, which will hopefully end up being something that can be taught to future generations.
The art of food preservation has been present in human food culture for thousands of years, and something that started out as a method of survival has grown into an entire arena of creative ways of changing flavor and texture. Food preservation can be done in a number of different ways, and in the spirit of seasonal cooking practices, we’re going to explore 9 methods today.
What is Food Preservation?
Put simply, food preservation is stopping the decay of organic matter. More specifically, food preservation is preventing the growth of microorganisms that oxidize fat and cause rancidity (microorganisms like fungi and yeast).
By removing water and oxygen from fruits, vegetables, and meats, it stops their capability of decay and instead preserves the wonderful nutrients they possessed when they were still alive.
One of the most inspirational cookbooks I’ve ever encountered is Six Seasons: A New Way With Vegetables, by Joshua McFadden. This way with vegetable isn’t exactly new, but more like ways humans have always approached seasonal cooking — but have sadly forgotten about with the development of industrialized agriculture.
In this book, the year is separated into six stages: spring, early summer, midsummer, late, summer, autumn, and winter. Each season comes equipped with food preserves that were prepared the season prior, fully extending the decadent flavors of summer harvest into the colder months.
One doesn’t need their own garden to get into the practice of food preservation. By paying attention to what is in season in the supermarkets and reserving some of that supply for preservation, you can be tasting fresh flavors of strawberry and tomato in the bitter grip of February.
This cookbook equips you with how to prepare your own butter with spring onions, escabeche pickled broccoli, honey preserved strawberries, and many more ways to bring bright flavors into each coming season.
Nine Methods of Preserving Food
Natural food preservation methods have preceded human history, and have evolved with the development of temperature-controlled environments. What originally began as a way of surviving winter months has evolved into a cherished practice to feel more self-sufficient.
Cherishing flavors of the seasons results in creative ways of extending their life, and this can be done in 9 different ways. Starting with the oldest method to the newest: fermentation, drying/dehydrating, salt and sugar curing, vinegar pickling, olive oil immersion, alcohol immersion, minimal processing (root cellars, and cool storage), canning, and freezing.
Fermentation is often referred to as living culture food, and this is the method of food preservation that has been around the longest. The science of fermentation is called zymology, and it involves a chemical change in food that uses organic acids to change microorganisms under anaerobic conditions. Anaerobic conditions occur without the presence of oxygen. This environment encourages a microbial conversion of sugars and starches into alcohol, which itself is a natural preservative.
By sealing a food product along with a starter culture, like salt or whey, you are changing a low acid food into a high acid food. Fermented food is stuffed to the brim with probiotics, and is one of the easiest foods for humans to digest. Fermentation has proven to be the method of food preservation that conserves the highest amount of nutrients in a fruit or vegetable.
Fermented foods you may be familiar with are:
- sourdough bread
Fun Fact: certain case studies have found that people who suffer from celiac disease (inability to digest gluten) are actually able to ingest properly fermented sourdough bread without feeling ill!
The dehydration of fresh food has proven to be present in human food culture since around 12,000 BC. When fresh food is dehydrated, it means that all water present in fruit, vegetable, or meat, is completed removed. Why? Because with the presence of water, comes the presence of bacteria and mold.
This is accomplished by taking your product, slicing it very thinly, and drying it by force of the sun, air, smoke, or wind. Before commercial dehydrators, meat was thinly sliced and often put into smokers, as smoking techniques quicken the drying process and also add antimicrobial agents that aid in preservation.
Nowadays if you’re looking to preserve something by drying it, you can slice it very thinly and let it hang to dry in a well-ventilated area. Alternatively, you can oven dry it by setting the oven to 140 degrees- Fahrenheit, prop open the oven door, and place a fan beside the gap to encourage circulation. This isn’t an ideal method as it uses up a heap of energy.
Traditional dehydrated meats:
- Dried Haddock (traditional in Icelandic culture)
- Biltong (traditional South African meat jerky)
- Beef Jerky (obviously needs no explanation)
- Prosciutto (high quality dried pork from Italy)
- Dried Reindeer (traditional indigenous Finno-Ugric dried meat)
Fruits that are great for drying:
3. Salt & Sugar Curing
Like we learned in the process of dehydrating food when food has water it also has bacteria. Salt and sugar curing is another method of drawing out the water through osmosis. This interferes with microbial growth, like bacteria and mold. Salt cured meat was a revolutionary method of preservation when transporting food on long sailing ventures up until the 20th century (when refrigerators were invented).
Salt curing occurs with thinly sliced meat, which can then be rehydrated when cooked in water. This method is usually combined with food dehydration as well.
Sugar curing can be done with granular or liquid sugar, like honey. The earliest cultures of food preservation would use honey to preserve fruits (and sometimes valuable body parts too!). Granular sugar is most often used for citrus fruits and skins, whereas liquid sugar is used for fleshy and juicy food like peaches, plums, and pears.
4. Chemical Pickling
So now that we’re familiar with how microbes interact with food and result in decay, we know that they can’t survive if there is no water or no oxygen. They also can’t survive in environments that are highly acidic.
Pickling can be categorized into two separate avenues: fermentation pickling (which we already learned about in section one) and chemical pickling. Chemical pickling occurs when food is placed in an edible acidic liquid that kills bacteria. This can be achieved by using: vinegar, brine, oil, or alcohol.
4.1 Vinegar Pickling
Vinegar is considered an antimicrobial agent, and bacteria cannot survive in it. The preserve doesn’t need to be heat treated and can stay edible for an indefinite amount of time. This can be done with any kind of vegetable, fruit, or even meat! Ever seen pickled eggs on your grandmother’s shelf?
4.2 Brine Pickling
Brine is an extremely salty liquid. We already know that salt draws water out of food, and combining salt with a tightly sealed lid stops decay in its tracks. It’s important that the food is cooked, then completely cooled before sealing the lid, as it can potentially trap living bacteria inside.
5. Olive Oil Immersion
This is a method of food preservation that completely locking oxygen out of the equation. Oil is a natural preservative, just like honey is, and by sealing food in a tightly sealed jar with olive oil, an anaerobic environment is established.
Immersing a product in olive oil is often combined with some sort of chemical pickling, where it will first be cooked in vinegar to ensure proper preservation (otherwise something called botulism can occur, which I will explain later on). Ever wonder why tuna and sardines stay good in the can? It’s because they’re immersed in olive oil, without the presence of air.
6. Alcohol Immersion
This process functions in the exact same way as chemical pickling or dehydrating, but simply with the use of alcohol. Alcohol draws any traces of water from a vegetable, fruit, or piece of meat and halts all microbial activity.
If properly sealed, submerging food in alcohol can preserve it almost indefinitely. Alcohol is a highly hostile environment for microbial life, and this is why people drink hot toddies when they’re feeling sick! Alcohol is extremely efficient at killing bacteria.
7. Minimal Processing – Root Cellars & Cold Storage
Cold storage is a shorter-term solution to food preservation. This method keeps produce edible for up to a season and is usually implemented by people who have homes equipped with root cellars and pantries.
A root cellar can be anything from a literal hole in the ground to an earthen room, to a weird stone dungeon in your grandma’s basement (I may be speaking from personal experience). The goal is to provide an environment that has no direct sunlight and is properly ventilated. The temperature should be between 50-60 degree-Fahrenheit, and around 90-95% humidity.
This method obviously works better in climates that have cold climates, and it’s historically been used as a way to extend the harvest season. It is very important to provide ventilation. The real magic happens at night time when the environment in the cold storage area grows colder, and the hot air rises. If there is no ventilation, the hot air will linger in the room and decay the food.
This should only be done with certain kinds of fruits and vegetables, and always ensure there isn’t a slightly decaying individual in the pile, as it can ruin the entire bunch.
Root cellar appropriate items include:
Food preservation through canning can be done with either sealed tin cans or glass jars. This is another way of removing oxygen from the equation, but first, the vessel needs to be heat treated before it can properly preserve its contents. Canning involves cooking the food you’d like to preserve, sealing it, then boiling the container to sterilize any remaining bacteria inside.
This is best done with foods that are highly acidic, with a pH level of at least 4.5 or lower. Studies have found that canning is a way of food preservation that also preserves dietary fibers, and ends up being far healthier than foods that are frozen.
Literally, anything can be canned, but a few mentionable products are:
Now for the modern version of food preservation: freezing. This is a method of preservation where the product most resembles fresh produce once it’s thawed. Freezing slows down the process of decomposition by turning water into ice crystals, which in turn freezes bacteria. The bacteria is technically still alive, and this is why a thawed product has to be cooked immediately.
Natural food freezing has been done for centuries, especially in northern communities where the majority of the year is close to freezing. Literally, anything can be frozen, but the main downfall with frozen food is that nutrients in frozen food tend to be reduced by at least 50% during the process.
There is only one downfall to food preservation, and that is an occurrence called botulism. This occurs when food is either not sealed properly, or not heat-treated properly. It happens most often with nonacidic food (that being said, it is still an extremely rare occurrence).
C. Botulinum is a germinated spore that produces a toxin. This toxin results in a paralytic illness when ingested by humans, starting with muscles in the face and spreading to the rest of the body. C. Botulinum prefers environments with low oxygen (that’s why proper sealing is crucial) and is resistant to heat if oxygen is present.
It is important to be aware of botulism and to take care of properly sealing and heating your preserves, but once again it is a very rare occurrence as the conditions for C. Botulinum are very particular.
Is food preservation important?
This is all based on personal preference, but one could make the argument that food preservation is important if one is looking for self-sufficiency. By not depending on supermarkets for all of your produce in the winter. It saves you money, it saves energy from the demand of growing certain products in winter months, and saves storage energy, transportation energy, there really is no limit to how much energy food preservation saves.
How does food preservation work?
Food preservation occurs by removing water and oxygen from fresh products to delay or stop the process of decomposition. Bacteria and fungi live in water, and once water is removed, microbial life comes to a standstill. This makes it safe to eat for longer.
Why is food preservation necessary?
It used to be necessary for human survival during winter months. Now, food preservation is necessary to be less reliant on supermarkets and the industrial agriculture system.
What are the benefits of food preservation?
In certain cases, like fermentation, the preservation process actually introduces super healthy and beneficial nutrients to a food product. Food preservation extends the shelf life of any product and allows you to keep different flavors throughout colder months. It saves money from buying fresh produce. And by lessening the demand for fresh produce in winter months, it removes enormous energy demands from industrial farmers.