A very large part of the history of cooking is dedicated to the preservation of food. Initially, people developed methods for saving food accumulated during seasons of abundance to be consumed during seasons of scarcity. Modern developments in transport, exploration, warfare, urbanization and industrialisation provided further impetus to the need to preserve food.
Fermentation, pickling, canning, freezing and freeze drying, drying and dehydrating, brining, cooling and chilling, and sterilization are all popular methods of food preservation in use today.
Although our need for preserving food at home has been all but disappeared with the introduction of refrigeration, commercial preservation and supermarkets, we all still enjoy a great pickle. If once we pickled at home to preserve, we now pickle for fun and deliciousness.
Food spoils because of bacteria and fungi. Both these organisms release enzymes that break healthy cells down and turn it into food for the organisms. If humans consume such (spoiled) food, we can get very sick or even die. The fact that we are repelled by the smell of decay (rotting) is our first, instinctive, line of defense against food poisoning.
At least three elements play a crucial role in the decay of food:
- Temperature: High temperature kills proteins and enzymes that cause decay; and low temperatures prevent and slow down their growth.
- Oxygen: Most (but not all) organisms require oxygen to stay alive.
- Water: The organisms that cause decay require water to stay alive; without it, they die.
It is thus logical that preservation techniques are based on the control of one or more of these elements. Canning combines heat and lack of oxygen. Cooling or chilling perishable foods at 4 ˚C prevents the reproduction of enzymes (but does not kill them).
Freezing does the same and prevents the absorption of water (because it is now ice). Drying removes water by means of evaporation and curing does the same but by means of osmosis (facilitated by the addition of sugar and salt). The acid used in pickling creates an acidic environment (solutions with a pH level below 7 is considered “acidic”) that curtails the growth of microorganisms and enzymes.
Sadly, with the growth of the modern food system, and the convenience that it brought, many home cooks have lost even the most basic food preservation skills. You might say, “We are in a pickle, because we can’t pickle no more”.
But just what is in a pickle?
In formal terms, pickling is the process of preserving food by creating an anaerobic fermentation in brine or vinegar. When salt is used, water is drawn from the raw product, which is then left in a sealed container to ferment. The fermentation occurs in the natural brine that is formed as a result. Many varieties of sauerkraut and kimchi are produced in this manner.
Food pickled with vinegar (acetic acid) requires a pH level 4.6 or less.
Thus, in their original form, pickled food taste either salty or sour. To create more complex flavour profiles, additional flavorings such as sugar, herbs and spices are added.
In the home environment, it is important to sterilize pickling equipment especially the storage containers (glass jars) by boiling or steaming them at high temperature for some time. The fruit or vegetables are added to the sterilized containers after which the pickling liquid is added.
The pickles are then left to ferment until the desired flavour profile is attained. Depending on the product, the strength of the pickling liquid, the temperature and the oxygen levels, this could take anything from a few days to a month or more.
Fortunately, with more modern techniques, we no longer have to wait that long before enjoying our pickles. One technique to “flash pickle” vegetables such as cucumbers, is to combine the (usually chopped) product with the pickling liquid in a vacuum bag and then to vacuum the contents. The vacuum machine extracts all air (thus also oxygen) from the bag and breaks cell walls under the pressure of the vacuum. This “forces” the flavour in the liquid into the food meaning the pickles are ready after only 20 minutes to an hour.
A very similar technique involves the use of a whipping siphon (the kind used to make whipped cream) charged with pressurized gas. The pressure causes the same reaction as the vacuum.
Someone brought me a generous gift of horned melons (Cucumis metuliferus) from their farm. So to preserve some of them for the time when nature’s pantry will be closed, I pickled most of them. They are quite delicious even tough they have a very fragile structure. I use them on sandwiches, in potato and green salads or with pickled fish. Given that they are mostly water (even more so than normal, domesticated cucumbers) you should consume them quickly or they will turn to mush and water. The pickling liquid could be used for other vegetables such as onions, spring onions and domesticated cucumbers.