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Food preservation Techniques - Coggle Diagram
Food preservation Techniques
Reduces risk of contamination in the food
Microbes- food poisoning/spoilage organisms
chemical/enzyme action
oxidation and hydrolysis
pests
environmental contaminants
ensures a certain shelf life
Cold Preservation techniques
refrigerator storage at <5^oC
Freezing - retards growth of microorganisms but can alter food texture
Quick Freezing (-40c blast freezing or -196c liquid nitrogen) - small ice crystals form, blocks metabolism, small drip loss, and doesn't change flavour or colour
Slow (home) freezing - Large ice crystals form, disturbs metabolic effects, increased drip loss, changes flavour and colour, causes freezer burn
Thawing - temperature rises rapidly, risk of microbial growth - should always be done in the fridge overnight
Canning
Cleaning
Blanching -reduces bacteria
Filling under a vacuum and exhausting to get the correct pressure
Seaming - rolling over the edges
retorting - seals cans with steam
Cooling
Storage/transportation to consumer
Steps involved
Syrup and brine is added to improve heat transfer, draw the moisture out of the food and displace air
Moisture removal
freeze-drying
spray-drying
drum-drying
sun-drying
Non-thermal methods
Packaging
Chemical additives (preservatives)
Irradiation (radiation)
destroys microorganisms without heating or altering the food
Smoke Curing at >180c
Bactericidal effect
Cold Smoking 30c
No bactericidal effect
Acid Fermentation
Homolactic fermentation - uses lactic acid & bacteria
Heterolactic - for yogurt production
Pickling - uses acid (vinegar), salt , sugar & alcohol
Curing - salt, sugar, & sodium nitrate to remove moisture