Why fermented foods have longer shelf life?

Fermentation is a process of converting carbohydrates into alcohol or organic acids using microorganisms such as bacteria or yeast. This process preserves food by inhibiting the growth of spoilage microorganisms that cause food to rot or become unsafe to eat.

There are several reasons why fermented foods have a longer shelf life:

1. Production of Lactic Acid: During fermentation, lactic acid bacteria (LAB) convert the natural sugars present in food into lactic acid. This acid acts as a natural preservative by lowering the pH of the food, creating an acidic environment that inhibits the growth of harmful bacteria. The acidic environment also helps to prevent the growth of molds and yeasts.

2. Competition for Nutrients: The microorganisms involved in fermentation consume the nutrients that would otherwise be available to spoilage microorganisms. This competition for resources limits the growth and multiplication of spoilage bacteria, thereby extending the shelf life of the food.

3. Production of Antimicrobial Substances: Some microorganisms involved in fermentation produce antimicrobial substances such as hydrogen peroxide, bacteriocins, and organic acids that can inhibit or kill other microorganisms. These antimicrobial substances further contribute to the preservation of fermented foods.

4. Lowered Water Activity: Fermentation can reduce the water activity (the amount of free water available) in food by converting water into other compounds such as lactic acid. A reduced water activity inhibits the growth of microorganisms that require a higher water content to survive.

5. Changes in pH and Redox Potential: Fermentation alters the pH and redox potential (the measure of the tendency of a substance to gain or lose electrons) of food. These changes create an environment that is unfavorable for the growth of spoilage microorganisms.

The combination of these factors, including the production of lactic acid, competition for nutrients, production of antimicrobial substances, lowered water activity, and changes in pH and redox potential, contribute to the extended shelf life of fermented foods. Fermented foods can be safely stored for longer periods compared to fresh or unfermented foods without compromising their safety or quality.