Lecture: new food processing
technologies
Processing = transformation of raw ingredients into products fir for human consumption.
- Improve digestibility
- Taste
- Nutrient uptake
- Appearance
- Safety
Steps involved in processing
- Separation: separation of different raw materials
- Conversion: converting raw materials in different forms
- Structure formation
- Stabilisation
- Packaging
With all these methods we control three things: pH, temperature and water activity.
, Freezing inactivates all enzymes and bacteria present in a food product and that way the food can
last for a longer period of time than cool food. In these cases some bacteria are destroyed due to ice
crystals, they can damage the cell walls of vegetables and foods but also the cell walls of bacteria!
However, not ALL bacteria will be destroyed and the enzymes are not inactivated permanently.
Drying decreases all available water (low water activity).
Salting reduces water activity of food because the cell will be mixed with water. The ions of sodium
and chloride are going to mic with water molecules and that make them not available for bacteria or
enzymes. In that way you can decrease microorganism growth.
Fermentation yeast or bacteria are used in a food product to give a desired flavour and texture. It
transforms characteristics of food product due to chemical compounds (antimicrobial activity) that
decrease microorganism.
Food additives are substances that are added to food with specific technical purposes. Antioxidants,
stabilizers, preservatives, packaging gases etc. Only substances that are not normally consumed in
the product can be considered as additive. There are a lot of regulations about additives. In EU we
have E numbers.
Heating is used most because it helps the possibility to keep the food for a long period of time and
decrease food born diseases. In heating there is confection and conduction.
- Confection = in liquid forms. The molecules that are being heated are moving. The molecules
tend to move up to the surface and the cooler molecules are going down. Then we have the
situation that many times we have cold point because not all molecules start moving, so the
heat transfer is not uniform. If you do not heat for a long period of time you have a higher
change of cold points. The cold points represent situations were bacteria that are within the
cold points start reaction which creates spoilage or toxic compounds.
- Conduction = in solid forms. Molecules are not moving around after heating. The heat comes
in a molecule, the molecules get heated and then they start transferring heat to another
molecule that is less heated. So, moving from outside to inside. In the center of the food
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