Principles of Preservation - Week 9 Flashcards
Spoilage
the process in which a food deterioates to the point it is unediable
Preservation
Treatment of food to prevent or delay spoilage or growth of microorganisms
Economic/Social reasons as to why we preserve food
Minimizes waste
Minimizes Environmental Impact
Logistical advantages
Consumer expectations
Things that cause food deterioration
Bacteria ( Pathogenic or Spoilage) Moulds Yeasts Oxygen ( Oxidation of fats causing rancidity) Enzymes Pests
Pathogenic bacteria causing spoilage
E-Coli0157
Campylobacter
Spore forming C. Botulinum
Name a Spoilage bacteria and how it works
Lactobacilli
Breaks down nutrient material giving stinky odours
How do moulds work
Visible colonies leading to food break down
Require minimum Aw 0.8 and oxygen
Fact recall: Yeasts
Cab grow in acidic environemnts
Requires moisture Aw 0.9 minimim
Cause taint in food products and effect quality
Types of preservation
Salt Sugar Smoking Pickling Chemical additives Fermentation
Non chemical preservation
Heat (Pasteurisation)
Cold temp
Water activity (Dehydration, Aw control)
Oxygen removal (Vacuum Packaging, Modified atmosphere packaging)
Factors that effect deterioration
Type of food Temp Aw ( Freely available water for micro organisms to grow) Atmosphere pH Competition
How does salting work and what is it used for
Reduces Aw and deactivates enzymes
Used in meats and fish
How does sugar work and what is it used for
Causes bacteria to lose water
Fruits (preserves)
How does smoking work and what is it used for
Adds antibacterial chemicals and reduces the Aw
Used in fish but also things like cheese
(Can be for taste as oppose to
How does pickling work and what is used for
Vinegar lowers pH
Salt Solutions lead to fermentation which lowers pH
mainly in fruit and veg
Chemical Additives
Benzoates, Nitrates and sulphites
Adverse, Nitrate may be cancer causing
How does fermentation work and what is it used for
Conversion of carbohydrates to alcohol or organic acids under anaerobic conditions
used in fruit,veg,meat,dairy
How does pasteurization work and how is it done
Destroys pathogens extending shelf life
71.70 degrees for 15 seconds
what is the Botulinium cook and what is it used for
121 Degrees for 3 minutes
Used in canning to control Cl. botulinum
How does cold treatment work
Slows/Stops Bacterial action and enzyme activity
How is does removing water work
reduces Aw below minimum required
how does removal of oxygen work to preserve a food
Bacteria cannot aerobically respire but Cl. Botulinum is an anarobic organism so this brings its own problems
How does irradiation work
Food is exposed to electron, gamma or x rays
Food safety v quality example
Canning is very good as it has very long shelf life but food loses colour and nutritional value
Refrigeration is very good retaining food in its original state and having good nutritional value but it has a very short shelf life
Disadvantages of preserving food
Lowers quality
Lowers Nutritional Value
Increases cost
storage costs
