🍲 Principles of preservation
Principles of preservation.
Food preservation works by destroying microorganisms, slowing their growth, or creating conditions where spoilage organisms cannot multiply.
Preservation by Heat
Heat destroys microorganisms and inactivates enzymes.
Pasteurization
Sub-100 degree C heat treatment that destroys many, but not all, microorganisms. Usually combined with refrigeration, sealed packaging, or other hurdles.
Heating near 100 degree C
Used for boiling, hot filling, blanching, and similar operations in selected products.
Sterilization above 100 degree C
Used for complete microbial destruction in canning systems, especially for low-acid foods requiring pressure processing.
Preservation by Low Temperature
Low temperature slows respiration, enzyme activity, and microbial growth.
Cellar storage provides limited short-term protection, while chilling (about 0-5 degree C) offers better control for many perishables.
Proper humidity and airflow management are critical during chilled storage.
Preservation by Chemical Preservatives
Permitted preservatives inhibit microbial growth by interfering with cell function.
Two classical examples in fruit products are sulfur dioxide (often through KMS) and sodium benzoate.
Efficacy depends on pH, concentration, temperature, and product composition. Legal limits must be followed.
Preservation by Fermentation
Fermentation uses selected microbial action to generate protective compounds such as alcohol, lactic acid, or acetic acid.
Products like pickles, vinegar, and fermented beverages rely on this principle.
Preservation Strategy as Hurdle System
Most practical systems combine methods, for example heat + acidity, or chilling + hygienic packaging, to improve stability and safety.
Selecting the right combination depends on food type, target shelf life, and quality objectives.
Summary Cheat Sheet
| Method | Core principle | Typical use |
|---|---|---|
| Pasteurization | Partial microbial kill below 100 degree C | Juices, beverages, milk-type systems |
| Sterilization | Complete microbial destruction above 100 degree C | Canned low-acid foods |
| Chilling | Slows biochemical and microbial activity | Fresh produce storage |
| Chemical preservation | Inhibits microbial growth via additives | Squashes, cordials, pickles |
| Fermentation | Produces protective acids/alcohol | Pickles, vinegar, fermented foods |
References
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References
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