Food Processing Fundamentals and Principles
Food processing turns raw agricultural material into safe, stable and convenient foods. This domain tests unit operations, material balances, yield and recovery calculations, heat and mass transfer basics, and how process objectives such as safety, shelf life and quality are achieved without unnecessary loss.
Core rules
- Unit operations fall into preparation (cleaning, sorting, peeling, size reduction), conversion (heating, freezing, drying, fermentation) and finishing (packaging, storage).
- Mass balance: input = output + losses + accumulation. Yield = output ÷ input × 100; recovery refers to the target component, not total mass.
- Water activity (aw), pH, temperature and time are the main hurdles controlling microbial growth and enzyme activity.
- Process severity must match the product. More heat is not automatically better because it can destroy nutrients and texture.
Worked example
1000 kg tomatoes contain 5% total solids. They are concentrated to a paste with 10% total solids, with no solids loss. Solids = 1000 × 0.05 = 50 kg. Final mass = 50 ÷ 0.10 = 500 kg. Water removed = 1000 − 500 = 500 kg. The reasoning uses the conserved solids component, not the total mass.
Traps
- Dividing by the initial mass when the basis has changed.
- Confusing yield with recovery of a specific component.
- Ignoring losses in peeling, trimming or spillage.
- Assuming a unit operation improves safety without a validated critical limit.