Science with Richard Bleil
My friend tells me that her garden is producing cucumbers like my life produces heartaches. Seriously, she tells me that she’s giving them away like something that gives a lot of something away.
Okay, so, I’m a little bit off of my game today.
I asked the obvious question. Are you going to pickle any? Apparently, she had never pickled cucumbers before. Okay, well, neither have I, but still…I love pickles. Heaven knows I’ve been in enough of them through the years. I also suggested that she add some red pepper to the pickles. My father taught me this trick; if you add a couple of dried red peppers (or crushed red pepper) into a jar of dill pickles and let them sit for a few months, you get spicy dill pickles. They are delicious.
Pickling has a long history. Prior to reliable refrigeration, it was basically a way to preserve foods. My friend from Hungary once brought me a sausage from his home that had never been cooked. It was WONDEFUL. The secret is that it was salt cured, so even though it had never been cooked, it was completely safe.
When you cook food, it really does a couple of things. First, the heat denatures proteins, killing off microbes. On top of that, if it’s a dry cook (like in an oven or over a fire), it also dries out the food, driving off water. My regular readers may recall my post on viruses, but with the exception of these odd little molecules, all life requires water to live, including bacteria. Thus, harmful microbes like those that cause salmonella cannot survive without water.
Pickling and salt curing work by basically drying out the foods. Salt curing basically means putting the meat in a vat of salt for quite a long period of time. The salt draws water out of the food using what is called “osmotic pressure”. Osmotic pressure is a force in which water flows from a region of low concentration (the meat) to high concentration (the salt). It’s a measurable force, actually, powerful enough to actually draw moisture out of the cells themselves, including the cells of potentially harmful microbes.
Meats prepared in this way do not require refrigeration. In an odd sense of the word, the meat and food is “mummified”. If any bacteria or microbes come into contact with this meat, the meat, with very little moisture left in it, will draw the water out of the microbe killing it. Nothing can live on it, so refrigeration is not necessary. Consider honey, for example, which is a sugar solution that requires no refrigeration or preservatives. Any microbes that come into contact with it loses its water through osmosis, and the microbe dies.
Pickling is very similar, except the osmosis utilizes a “brine solution”. It seems odd to think of something watery, like pickle juice, causing dehydration, but it does. The secret is that the brine solution is a very high salt concentration. So even though one dissolves brine salt into water, the concentration is still such that it will draw water out of food through osmosis. This is why cucumbers shrink during the pickling process. You drop a plump cucumber into the brine solution, and water is drawn out of the cucumber. As water leaves the cucumber, the vegetable will shrink as the mummification process occurs.
Jerky is a similar process, but often done with low heat. Slices of meat are marinated and often placed in a dehydrator, but all a dehydrator does is apply a low heat for significant time. I’m looking at a recipe that includes oven dehydration instructions, which basically means setting the oven to low heat and letting it dry out for eight hours. At this temperature (175 in the recipe I have), it’s not an attempt to kill bacteria with heat. Instead, over an eight-hour period, water will dry out of the meat, leaving it, well, dehydrated. Without water, the meat needs no refrigeration because nothing can live on it.
As you might imagine, this is basically winter survival and war technology. After all, if your army is expanding throughout the world, getting further and further from their homeland (think the Roman army), getting food to the outermost troops without poisoning them is an enormous problem. Romans actually developed cheese as a dense and safe way to transport dairy without refrigeration. Pickling was developed as a way to preserve foods from harvest time throughout the year when there is no harvest available. All I know is that my friend owes me hot, spicy pickles.