1. Food preservation

2. Food preservation What is food preservation?
Food preservation is the process of treating food to stop or slow down food spoilage, loss of quality or nutritional value.
What is its main aim?
Food preservation has the main aim to prevent the growth of bacteria and other microorganisms, in order to extend the shelf-life of food and ensure its safety and quality.

3. Classification of food preservation methods
Physical methods
Pasteurization
Refrigeration
Freezing
Canning/bottling
Drying/dehydration
Irradiation
Chemical methods
Salting
Sugaring
Marinating
Natural/artificial additives
Biological methods
Fermentation (cheese, wine, vinegar, beer, etc.)
Physico-chemical methods:
Smoking

4. Physical methods
Pasteurization: Food is heated and then cooled immediately (thermal treatment).
Canning: Food is cooked and preserved in sterile containers (thermal treatment).
Drying /Dehydration: Food is dried in air, in the sun or using gas, or is vacuumed. It prevents bacterial growth by reducing water activity (bacteria do not reproduce without moisture). Ex. Air drying for herbs.
Irradiation: Food is exposed to x-rays radiation.
Refrigeration: Food is stored at temperatures below 4 °C.
Freezing: Food is stored at temperatures below 0°C.

5. Chemical methods
Preservation in a liquid: Food can be preserved in a liquid such as wine, vinegar, lemon juice, alcohol, oil, brine.
Salting: this method prevents bacterial growth by reducing water activity (bacteria don’t reproduce without moisture)
Sugaring: food is cooked with sugar. Water evaporation prevents food spoilage (heat + water activity control)
Artificial additives: they are antimicrobial and antioxidant preservatives: they prevent bacterial growth or food oxidation, but may be toxic if used in large quantities.

6. Physico- chemical methods
Biological methods
Physico- chemical methods
Fermentation: it is a method based on natural processes. Yeasts and good bacteria are responsible for food fermentation (milk becomes yoghurt, alcohol becomes vinegar, etc...)
Smoking: food is cooked with or exposed to smoke (heat causes dehydration and food reacts to smoke).

7. Preservation processes have advantages and disadvantages:
food spoilage is prevented
longevity of food increases
Disadvantages:
nutrients can be lost and the nutrititive quality of preserved food can be lower (especially if the process is based on thermal processing)
Alteration of taste
Too many additives may be toxic

8. The hurdle concept
Hurdle means barrier. The hurdle concept is based on one principle: if there are many barriers, pathogenic microorganisms in food will be eliminated or at least inactivated. These barriers can be: high temperature (cook), low temperature (chill), reduction of water activity, acidity, preservatives.

9. Useful vocabulary
smoking: affumicatura canning/to can: inscatolamento/inscatolare dehydration: disidratazione
to preserve: conservare
to treat: trattare
to ensure: assicurare
to slow down: rallentare
shelf-life: durata, vita
spoilage: deterioramento
loss of quality: perdita di qualità
advantage/disadvantage: vantaggio/svantaggio
to increase: aumentare
hurdle: barriera
heat / to heat: calore/riscaldare
to cool/to chill: raffreddare
dried/ to dry: essiccato/essiccare