Since the beginning of time, humans have searched for safe and effective ways to preserve food. When done properly, preservation prevents food from spoiling. Depending on the method you use, preservation may extend the shelf life of some foods for several months or years.
But how does preservation work? What is the science behind some of the most popular and traditional methods?
Humans likely discovered the preservation effects of smoking food by accident. Meats, fowl and fish that were cooked over an open fire and exposed to smoke lasted longer than foods that did not.
Why is smoking an effective preservation technique?
Certain compounds in wood smoke have antimicrobial effects, which prevent the growth of the bacteria that spoils food.
Today, there are many methods used to smoke foods, including both cold and hot techniques. Hot smoking is a great choice for fresh or frozen food, while cold smoking is ideal for salted products and cheese.
Because there are so many preservation methods available today, smoking is primarily used to give foods distinct flavors, rather than preserving them.
Drying is another popular food preservation method, and a highly effective one. Because bacteria and other disease-causing organisms can only thrive in a moist environment, drying is one of the simplest ways to prevent spoilage. In ancient times, humans used the sun and the wind to dry out foods.
Drying was likely the earliest form of food preservation, and evidence of this technique dates all the way back to the earliest days of recorded history.
Over the centuries, the method of drying foods has progressed and advanced to make the process less time consuming.
Today, we use a food dehydrator to simulate the effects of drying food out in the sun and wind. These appliances use low-temperature heat and fans to remove moisture from foods. While faster than drying out in the sun, dehydration still takes several hours to complete.
Freezing is a highly effective way to preserve food because bacteria and other pathogens that spoil food are either killed or are not able to multiply at low temperatures.
Freezing isn’t a perfect method, though. Some pathogens are able to survive cold temperatures, and in some cases, freezing simply deactivates the pathogen. Once the food thaws out, the pathogen will become active again.
Just like any other food preservation method, freezing will work better with some foods than others. Meat, fish, poultry and some fruit juices are common choices for this method.
Salting, or curing, is a very old preservation technique that’s still not well understood by science. We do know that salt binds with water molecules, so in some respects, this method acts as a way to dehydrate. A salty environment may also prevent pathogens from surviving.
No matter the science behind this method, people have been using salt to preserve food for centuries.
There are some factors that affect the efficiency of curing, such as the size of the food and its fat content. The concentration of salt and the temperature of the brine will also play a role in how effective this method is.
While it can be used with vegetables and fruit, curing is most commonly used to preserve meat and fish.
Fermentation is actually a natural chemical reaction that causes a food to convert into another form via pathogens, or bacteria. Technically, the food “goes bad,” but the end result is still an edible product. Cheese is the perfect example of fermentation. Milk has a very short shelf-life, but early humans quickly discovered that spoiled milk can be controlled to produce cheese.
Fermentation has been praised in recent years because many fermented foods, such as sauerkraut and kimchi, contain beneficial gut bacteria that aids in digestion and health.