WHAT IS FOOD PRESERVATION?
What is preservation actually? How do these basic ingredients end up with such different results? That’s the magic of preservation. All food decays. The enzymes in the fruit start work as soon as it's picked. Some decay can be good; think fermentation. But often it is bad and negatively affects both the taste and the nutritional quality of the food. The first step of food preservation is stop the enzymes from doing their thing. Two things stop enzymatic action, heat and cold. Pick one. If you pick cold, you’re on a path to making a fresh jam. If you pick hot, you’re making cooked jam.
The second aspect of preservation is preventing “the Ick” from invading your jam. "The Ick" is the legion of pathogens that would like to take up residence in your food. See, they think it's as tasty as you do!
There is a beauty to the mechanics of nature. The climate that we as humans enjoy is the same that pathogens find ideal. Their requirements for life are the same as ours. They, as we do, need the right amounts of moisture, temperature, acidity, and oxygen. The most basic tenet of food preservation is this: change one (or more) of the ideal conditions for life and you will stop any “the Ick” from contaminating your food.
You can think of it this way: Are you in a pickle? Well, you’re in an acid, or vinegar, bath and it’s uncomfortable. Pathogens don’t like it either. Feeling dried out when you eat too much salt or sugar? Sugar and salt absorb moisture. When sugar is used in a jam, the pathogens are deprived of moisture. Love jerky snacks? That’s the salt removing the moisture from the meat. Beyond the necessary requirements of the science to make your food safe is the incredible opportunity of flavors.
What’s the last requirement for “the Ick”? The same as it is for us, oxygen. That’s where the hot water bath processing or freezing comes in. The hot water bath process, submerging nearly full jars in a boiling water bath for prescribed time, is what drives any oxygen out of the jar and creates the anaerobic environment. When the jar is sealed, without oxygen, we’ve completed the safe preservation of the food. We’ve deprived the pathogens of their ideal environment and made it safe and delicious for us to store and eat.
Freezing can also create a low oxygen environment. It reduces the temperature so as to create the low oxygen atmosphere, but there can be drawbacks to longterm freezer storage. Lack of freezer space, power outages, decrease in nutritional value during storage, decrease in quality. The choice of preservation is determined by a number of personal criteria. In most cases, freezing is best for short-term storage as well as preserving small amounts. But for large batches of items for longterm storage, hot water bath processing works best.