Food Engineering Practice Test: Principles of Semi-Moist Foods — Flashcards

Semi-moist foods work on the principle of equilibrium. When dry, they absorb solution, and when wet, water is washed out by diffusion with another liquid. 

Semi-moist foods are also known as Intermediate Moisture Foods (IMF). They contain some water that is bound by glycerol, sorbitol, salt, or certain organic acids for a short period of time. This prevents the growth of many microorganisms. 

Semi-moist foods typically contain 11% to 20% moisture and have a water activity of 0.64 to 0.75. They are usually softer than dry food compositions and often have an elastic texture. 

Here are some other principles of food preservation:

- Chemical preservation: Uses chemical compounds like salt, sugar, and vinegar to extend the shelf life of food. These chemicals inhibit microbial growth, enzymatic activity, and oxidation.

- Freezing: Freezing conditions inhibit bacteria growth.

- Acid conditions: Acid conditions inhibit the growth of many microorganisms. Organic acids like acetic acid (vinegar), citric acid (lime juice), and lactic acids are commonly used for preservation.