The Use Of Salt & Sugar As Food Preservatives

Preserving today's surplus food for tomorrow is one of humanity's oldest concerns. Food has been preserved by the use of ingredients like salt, sugar, honey and smoke for hundreds or even thousands of years. In modern-day America inexpensive refrigeration and freezing have changed the way we eat, but smoke, salt and sugar are still used to preserve foods simply because they taste good.

Salt as a Preservative

Salt is one of the oldest and most potent of food preservatives. It works at the molecular level by a process called osmosis. When foods are exposed to salt, either dry or as a brine, it draws moisture out through the walls of the food's cells. Like us, bacteria and mold need water to survive, and salting or brining food removes enough moisture from foods that these microorganisms can no longer survive. Heavily salted foods can be kept for years, but require long soaking and precooking to be made edible.

Sugar as a Preservative

Refined sugar is thought to have originated in India approximately 2,500 years ago. Its use is described in a medical text nearly that old. This "sweet salt" did not become inexpensive and widespread until the 18th century, when Europeans planted sugar cane in quantity throughout their new tropical colonies. Like salt, sugar preserves foods by osmosis. If you've ever watched a bowl of strawberries becoming juicy under the influence of a spoonful of sugar, you've seen the effect in action.

Curing Foods

Most recipes for preserving fish and meats use a combination of salt and sugar. Not only is sugar a preservative in its own right, it adds a pleasant sweetness to the cured meats and moderates the harsh flavor of the salt. You can surround the food with either a dry mixture of salt and sugar or dissolve them in water to make a brine. The longer you leave your food in the salt, the stronger its flavor and more powerful the preservative effect. In some cases the cured foods will ferment, producing traditional-style pickles.

Jams, Jellies and Preserves

There is a unique class of preserved foods made with sugar and fruit. Jams, jellies and preserves all rely on sugar's affinity with a specific carbohydrate called pectin, found in the cell walls of fruits and vegetables. When you heat fruit juice or mashed fruit with enough sugar and acidity, the pectin in the fruit will thicken the juice into a firm gel. The effect only works with high concentrations of sugar, but the end result beautifully captures the color and flavor of the fruit or berries.