The history of food preservation is fascinating; for centuries people have salted, pickled, smoked, and dried their food to make it last longer without the aid of refrigeration. Imagine your life without your trusty refrigerator. I experienced it for a short time growing up when our family’s refrigerator stopped working. I don’t quite remember how long we dealt with not having one but it seemed like an eternity and it taught me to appreciate our avocado green Frigidaire a lot more when it was finally repaired. Luckily it was winter time and we had coolers set outside to store milk, juice, butter, etc. We also had a chest freezer that was styled like a ‘57 Chevy with chrome finishes and bulky rounded edges – it was a behemoth.
That experience taught me to examine foods that did not need refrigeration and that astounded me. My Dad would buy planks of dried salted cod fish or as we called it – Bacalhau. I was intrigued how a dried out piece of – once fresh fish – could last so long without spoiling. They were stiff as a board and looked inedible. It was remarkable to think how this once fresh fish with firm flesh, clear eyes, and no fishy scent was transformed into a piece of wood. But as we all know, fresh fish and houseguests start to stink after three days.
Long ago, someone thought about taking that fresh fish and drying it to remove all of the moisture. Ingenious, since bacteria requires a moist environment to survive and the fish can be kept for a long time without spoilage. Legumes (that bag of dried navy beans kicking around in the back of your pantry) that have been dehydrated last a long time because moisture-loving microorganisms are kicked to the curb with no place to live.
For centuries, salt cod was a major food export and is still integral in many European and Scandinavian cuisines. My family had bacalhau on holidays and even on not so special occasions. It was Portuguese comfort food at its best. I recall the large pieces of salt cod needing to be soaked in large stock pots of water to rehydrate it over a few days. The water needed to be constantly refreshed for the salt to be removed from the fish. One of my favorite things my Dad would make were bacalhau fritters – crispy on the outside and then a creamy, cod fish filling with potato and fresh parsley on the inside. Right from the fryer with a sprinkle of sea salt – so delicious!
Now, I think it’s important that we chat about fat Tom – no, not my portly friend who ate too many fritters, but an acronym. FATTOM reminds us what nasty microorganisms need to thrive and multiply. FATTOM is a simple reminder when it comes to food spoilage. Here’s what is necessary to spin the spoilage wheel.
Food – very simply, bacteria needs food to survive; Acid – microorganisms also like a certain pH balance, somewhere right in the middle (not too acidic, not too alkaline). The two T’s are for Time and Temperature – the longer food is left out at unsafe temperatures will allow bacteria a chance to grow and multiply. That is why it is very important to cool large portions of food before placing in the refrigerator. O for oxygen, yes bacteria needs it too! Moisture is the last piece of the puzzle as explained above in the dried fish example.
Drying food is just one of the ways to preserve it. Pickling, for instance, works because the liquid used to preserve the food item is very acidic, too acidic for bacteria to grow. By the way, bacteria also has two other pals in the spoilage world – including yeast, and mold. I think you get the point.
Coming full circle, let’s round out the general techniques of preserving food. We have dehydration, alcohol is used primarily for fruits (think pear brandy or eau de vie), sugar used in fruit preserves (sugar slows down enzymatic activity), pickling, dry cure or salt, a liquid cure/brine (think of that Thanksgiving turkey), smoking (think BBQ) but also include cold, hot and wood smoking, pasteurization (milk & dairy), sterilization (think of grandma’s canned veggies or fruits), refrigeration & freezing (including quick freezing & freeze drying), and lastly, sealing & coating – such as in making duck confit – basically the duck is dry cured to remove moisture and then cooked in its rendered duck fat. The layer of fat creates a barrier and microorganisms can’t get in to spoil that yummy goodness.
I hope this post about methods of food preservation proves interesting. I am definitely interested in learning to safely can (a bucket list food challenge) and I do love to quick-pickle a summer cucumber or red onion but most importantly, I think about honoring the ingredient and trying to reduce food waste as much as possible.