High concentrations of salt and sugar create an environment toxic to microbes by interfering with their internal processes, like DNA and enzymes.
Salt and sugar are ancient and effective methods for preserving food. They work primarily by creating conditions that are unfavorable for the growth and survival of microorganisms, such as bacteria, yeasts, and molds, which are responsible for food spoilage.
Creating a Hostile Environment
Both salt and sugar achieve preservation by lowering the water activity of food. Microbes need a certain amount of available water to grow and reproduce. When high amounts of salt or sugar are added, they bind to the water molecules in the food, making that water unavailable to the microbes. This process is known as osmosis.
Additionally, as highlighted in the reference "Salt Kills Microbes":
- High salt and high sugar concentrations are toxic to processes inside microbes.
- These include vital components like DNA and enzymes.
- High sugar solutions have the same effects on microbes as high salt solutions.
- This is why sugar is used as a preservative in foods like jams and jellies.
By disrupting essential internal functions such as DNA replication and enzyme activity, high concentrations of salt and sugar directly inhibit microbial growth and can even kill the microorganisms present.
Practical Applications
- Salting: Used for preserving meats (like jerky or cured ham) and fish (like salted cod).
- Sugaring: Commonly used for preserving fruits in jams, jellies, and preserves, as well as in candied fruits.
These methods create conditions under which spoilage organisms cannot thrive, significantly extending the shelf life of the food.
