Understanding The Art Of Modern Food Preservation
If you are interested in preserving foods, you may soon find that methods have changed dramatically over the years. There is no reason to use the same methods your grandmother used-see what changes have occurred, for our modern convenience.
Because food is so important to our survival, food preservation is one of the oldest technologies used by human beings. Even though we see and use many of these technologies every day, we often don’t realize how interesting they are.
So let’s take a look at some of the technologies that you can find in your home today. To understand how to save something, we first need to understand how something spoils.
The basic process is very simple: bacteria invades the food and causes it to rot. Technology therefore comes in two different forms.
Either the technology is trying to slow down the activity of disease-causing bacteria, or it is trying to kill the bacteria altogether and sterilize the food. A food that is sterile contains no bacteria.
Unless sterilized and sealed, all food contains bacteria. The food preservation technology that we are most familiar with is the refrigerator.
It takes the “slow bacteria down” approach. For example, germs naturally living in milk will spoil the milk in a few hours if the milk is left out on the kitchen counter at room temperature.
By putting the milk in the refrigerator, you don’t eliminate the bacteria already there, but you do slow it down enough to keep it fresh for a week or two. The same holds true for fruits, vegetables, meats, etc. that you keep refrigerated.
In the case of freezing, the idea is to stop bacterial action altogether. Frozen germs are completely inactive, so frozen food lasts for months.
In general, refrigeration has no effect on a food’s taste or texture. Freezing has little effect on the taste or texture of most meats, but often completely changes fruits (which become mushy).
Refrigeration’s minimal effects account for its huge popularity. Before there were refrigerators, canning was king.
Since 1825 or so, canning has provided a way for people to store foods for extremely long periods of time. In canning, you boil the food in the can to kill all the germs and seal the can (either before or while the food is boiling) to prevent any new bacteria from getting in.
Since the food in the can is completely sterile, it does not spoil. Once you open the can, germs enter and begin attacking the food, so you have to “refrigerate the contents after opening.”
One problem with canning, and the reason why refrigeration or freezing is preferred to canning, is that the act of boiling food in the can changes its taste and texture. Many foods are dehydrated to preserve them.
If you walk through any grocery store you may notice the following dehydrated products: powdered milk, dehydrated potatoes in a box, dried fruits and vegetables, dried meats (like beef jerky), powdered soups and sauces, dried pasta, etc. Since most bacteria die or become completely inactive when dried, dried foods kept in air-tight containers can last quite a long time.
Freeze-drying is a special form of drying. Food is frozen and placed in a strong vacuum.
The water in the food then sublimates – that is, it turns straight from ice into vapor. Freeze-drying is most commonly used to make instant coffee, but also works extremely well on fruits such as apples.
Salting, especially of meat, is an ancient preservation technique. The salt draws out moisture and creates an environment inhospitable to bacteria.
If salted in cold weather (so that the meat does not spoil while the salt has time to take effect), salted meat can last for years. You can read about salt’s use during the sailing voyages around the time of Columbus.
Many accounts of the Revolutionary War and especially the Civil War talk about meat preserved in this way. Today, we have the modern vacuum sealer.
By sucking all of the air out of special plastic containers, we can be sure that our food will stay fresh and germs will not be allowed to grow. This is becoming a very popular alternative.
Then there are the chemical preservatives-things like Benzoates (such as sodium benzoate), Nitrites (such as sodium nitrite), antioxidants like BHT and BHA, and Sulfates (such as sulfur dioxide). If you look at the ingredient labels of different foods, you will frequently see these different types of chemicals used.
These chemicals often have more of an effect on color and texture than they do on bacteria activity. Choose what method you fell would be best for you, and make sure your ingredients stay fresh for as long as possible!
Jack R. Landry has been working in the food preservation business for 31 years. One of his favorite products are seal a meal bags. He has written hundreds about food preservation.
Jack R. Landry