Define Food processing
- Any operation carried out on raw food is called process, which results in a processed food product
What are 5 reasons for for processing ?
- Preservation
- To make the food edible
- To enhance the nutritional quality of foods
- To make foods more convenient to consume
- Price reduction
What are the five principles of food preservation and explain each one ?
- Asepsis - keeping out the micro-organism : could be with things like a plastic wrap
- Slowing the growth of microbes : this could be by changing the conditions to slow the growth rate
- Inhibit growth of microbes : Conditions modified to fully inhibit the growth
- Killing the micro-organism : Intense heat treatment , UV treatment
- Controlling chemical reactions in food : e.g. fresh foods contain enzymes , such foods can be preserved by inactivating the enzyme
What is Pasteurization?
- The application of heat to a food product in order to destroy pathogenic microorganisms , to inactivate spoilage causing enzymes , and to reduce or destroy spoilage microorganisms
During milk pasteurization, what are the two treatments used ?
- Low temp long time (LTLT)
- High temp short time (HTST)
What is sterilization and give an example of commercial sterilization
- killing all microorganisms in the food is termed sterilization
- Ultra high temperature (UHT) milk is an example
What is the purpose of canning and what steps are taken while doing commercial canning ?
- To destroy almost all the microbes
1. Cleaning the food for canning
2. Filling the food in the can
3. Exhausting
4. Sealing the can
5. Cooking of the food in the sealed can
6. Allowing the cans to cool to room temperature
What is the purpose of Blanching and how is it done?
- Heat treatment is to inactivate the enzymes in the food
- you do it by briefly dipping the food in boiling water followed by cooling under cold water to stop cooking
What is the purpose of dehydration and what are the five ways to do it and explain each of them
- purpose is to remove water which will prevent microbial growth
- Sun drying - dried in the sun
- Plate drying(vacuum drying) - food placed on trays and is heated in a hot chamber
- Drum drying - usually used to make tomato soup, first soup is made then thickened by prolonged heating and the it is put in troughs which are installed under a large hot drum which rolls into the viscous soup
- Spray drying - done by atomizing the milk into droplets using a atomizer/spray in a hot chamber
- Freeze drying - removal of water under a very high vacuum
What is the purpose of refrigeration in preserving foods?
- to cool the food to above 0°C to 4°C to slow down the microbial growth
What is the purpose of freezing in preserving foods?
- Cooling the food to temp below 0°C to freeze water in food as the frozen water is not available for microbial growth, thus it halts microbial growth
What are some examples of directly and indirectly lowering pH to preserve food ?
- Directly : addition of acids such as acetic acids , vinegar , citric acid , tartaric acid , e.g pickles
- Indirectly : lowering the pH by fermenting bacteria that produce acid acid in food. e.g. yogurt
How can you preserve food by reducing water activity of food ?
- with things that absorb water when added, for example salt and sugar both absorb water when added to foods , which can help preserve the food.
What are the different packaging methods used and why are each of them effective?
- Glass
- can withstand high processing temperature
- Glass is rigid and provides good insulation but it is heavier and has poor durability
- impermeable to gases and vapor - Metals
- highly malleable and very durable
- impermeable to water, air/gases, microbes but some may react with food contents - Paper
- Light weight , cheap and biodegradable
- permeable to gases, moisture and fat and has poor strength - Plastic
- design flexibility
- chemically resistant
- Inexpensive
- light weight
- disadvantage is that it is permeable to light , gases , vapours and low molecular weight molecules
- not biodegradable but recycled
What does Controlled or modified atmospheric packaging (CAP or MAP) do and give some examples ?
- Concentration of gases in the package are controlled or modified
- Oxygen absorbent patched can be used to minimize the availability of oxygen in the package to minimize th fruit ripening during transport
- Nitrogen packaging of chips is another example , the potato chips are fried in oil and are packaged in bags filled with nitrogen to prevent rancidity
What are the four classes of preservatives ?
Class 1 : Curing preservatives
Class 2 : Antibacterial
Class 3 : Antifungal and antimycotic
Class 4 : Antioxidants
What are some examples natural preservatives ?
- traditionally table salt, sugars , acids
- But nitrates and nitrites have long been used in curing meats
What are some examples of synthetic preservatives ?
Class 2 : Sodium benzoate , sulphates
Class 3 : Propionates , sorbates
Class 4 : Ascrobic acid , butylated hydroxytoulene and. butylated hydroxyanisole
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Unit 1 : Basics of Nutritional Sciences25
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Unit 2 : Food Production31
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Unit 3 : Food Security and More24
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Unit 4 : Food Chemistry - Water10
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Unit 4 : Food Chemistry - Carbohydrates26
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Unit 4 : Food Chemistry - Lipids13
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Unit 4 : Food Chemistry - Protein22
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Unit 5 : Food Safety34
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Unit 6 : Food Processing18
