Food Processing Flashcards
What is food processing?
Food processing is the transformation of agricultural products into food, or of one form of food into other forms.
What causes food to spoil?
Microorganism - bacteria, yeast, moulds and fungi
Oxidation
Light
Rodents
Physical damage
How does oxidation cause food products to spoil?
Oxidation occurs when food interacts with air, resulting in undesirable changes in colour, flavour and nutritional content.
How does physical damage cause food products to spoil?
Bruises and cracks on raw produce, and damaged or poorly sealed packaging, can allow microorganisms, air and pests to enter. Microorganisms also cause physical contamination
How does food spoilage occur?
Food spoilage by microorganisms and yeast mould growth, due to nutrients and water content of food
Give 2 advantages of food preservation
Extends shelf life
Prevent spoilage by the action of microorganisms and enzymes
How does enzymatic browning occur in apples?
Phenols and the enzyme phenolase are found in the cells of the apple, and when these are exposed to oxygen in the air this triggers the generation of dark pigments (melanin)
Explain how food is preservation using freezing
Food temperature reduced below its freezing point and a proportion of water undergoes a change in state to form ice crystals.
Freezing solidifies water and thus makes it unavailable for bacteria
Temperature = -18 degrees
Explain the stages in the freezing curve
The temperature falls fairly rapidly to just below 0 degrees
Heat is removed in order to turn the bulk of the water to ice. Temperature remains constant - this is knows as thermal arrest
When about 55% of the water is turned to ice, the temperature begins to fall rapidly. A comparatively small amount of heat has to be removed during this stage
Give 2 pros and 1 cons of freezing
Pros: Frozen storage preserves food for months/ years if properly packaged, slows microbial growth and enzyme activity
Cons: Damage caused to cells by ice crystal growth
What does HTST AND UHT stand for
High temperature short time
Ultra heat treatment
Explain how and why pasteurisation is carried out
Relatively mild heat treatment: 63 degrees for 30 mins
Kills microorganism but not spores
Refrigeration is essential
Effects of pasteurisation on food
Minor changes to the nutritional and sensory characteristics of most foods
Shelf life of pasteurised foods is extended by a few days or weeks
Explain how and why HTST is carried out in milk pasteurisation
High temperature short time (HTST) is carried out at 72 degrees for at least 15 mins
Destroys mycobacterium tuberculosis and brucella abortis bacteria
Give 2 advantages of using heat sterilisation in food processing
Complete destruction of microorganisms to prevent spores formation
Sterilized foods shelf-life in excess of 6 months at ambient temperatures
Explain how UHT in milk is carried out and why
138 - 15o degrees for 1-3 seconds
Destroys all bacteria or spores
Denaturation of whey protein occurs
Continuous process and the product is packaged after sterilisation into sterile containers
Explain canning
Heat sterilisation and sealing under vacuum
Cans cooled in chlorinated water
Addition of other elements: salt, sugar, acid
Critical Ph 4.5 - below which clostridium botulinum is inhibited
Texture and taste changes
Longer shelf life at ambient temperature
Give 2 concerns in food industry with canning
Clostridium botulinum
Gram positive bacteria produces spores
Give 5 ways to control water activity/pH using preservation
Drying
Sugaring
Curing
Pickling
Fermentation
Explain the process of Irradiation
Using ionising radiation which kills bacteria and moulds, and insect pests
Explain the process of chemical preservatives and give examples
Antioxidants used to prevent wine oxidation (e.g. sulphites) and fat rancidity (e.g. rosemary extracts)
Explain the process of vacuum packing
Oxygen-free conditions to inhibit microbial growth
Explain the process of Modified atmosphere packaging (MAP)
Alters the proportion of oxygen in the pack (e.g. beef mince) by replacing with inert gases, such as nitrogen, to inhibit microbial growth
Pros of food packaging
Controls food immediate environments
Protects from damage
Provides a barrier to spoilage and disease- causing microorganism and pests
Protecting from oxygen, moisture, strong odours and light
Cons of food packaging
Package waste
Air and water pollution
Burning for energy can emit greenhouse gas and pollutants
Bisphenol A (BPA) presence concerns
What factors may influence chemical reactions and therefore nutrient content of foods?
Heat
Light
Oxygen
pH
Give 3 positive impacts of heat processing
Gelatinisation of starches (toasting bread)
Protein Coagulation ( fried eggs)
Anti-nutrition compounds in legumes and cereals grains are destroyed (oxalates, lectins, phytates)
Give an example of an oxalate
Calcium Absorption
Give examples of Lectins
Calcium
Iron
Phosphorus
Zinc Absorption
Give examples of Phytates
Iron
Zinc
Magnesium
Calcium Absorption
Give examples of 2 food preparation methods that reduce lectins and 2 preparation methods that increase lectins
Reduce: Soaking, Boiling
Increase: Roasting, Baking
Give examples of 2 food preparation methods that reduce oxalate and 2 preparation methods that increase oxalate
Reduce: Steaming, Soaking
Increase: Roasting, Grilling
Give examples of 2 food preparation methods that reduce phytates
Fermentation, Soaking, Boiling, Germination
Give some impacts that heat processing has on nutritional value of foods
Destroys heat-liable vitamins
Reduces biological value of proteins (due to destruction of amino acids or Maillard browning reactions)
Removes volatile odour compounds
Promotes lipid oxidation
Explain what the Maillard browning reaction is and the outline the steps in this process
The Maillard reaction is also known as non-enzymatic browning. It involves the reaction between reducing sugars and proteins by the impact of heat.
STAGE 1: Reaction of an amine with a reducing sugar with the formation of
glycosyl amine, followed by the Amadori rearrangement
STAGE 2: Dehydration of the intermediary products, fragmentation of the
saccharidic moiety, and the Strecker degradation of the products
STAGE 3: Reactions of intermediary products resulting in the formation of
heterocyclic flavor compounds, that is, high molecular weight brown
pigments, which are responsible for the typical flavour of brown product
Name 3 places where nutrient losses occur
Harvesting
Distribution
Storage
Name 2 things that can inhibit lipid oxidation
Antioxidants (Vitamin C,E)
Chelating Agents (EDTA)
Give 4 factors that affect variation in nutrient losses
Different cultivars or varieties
Growth conditions
Handling
Preparation procedures prior to processing
Name the 4 most labile nutrients
Vitamin A (Retinol)
Vitamin C
Folate (B9)
Thiamine (B1)
What processes’ causes Vitamin E to have the highest loss
Broiling
Roasting
Name the 4 water soluble vitamins
Vitamin C
Thiamine (Vitamin B1)
Riboflavin (Vitamin B2)
Folate (Vitamin B9)
Pantothenic Acid (Vitamin B5)
Niacin (Vitamin B3)
Vitamin B6
Vitamin B12
Biotin
Give 3 ways Vitamin C is loosed during cooking
Degree of heating (Sensitive to heat)
Leaching into the cooking medium
Surface area exposed to water and oxygen (easily oxidised)
Name the cooking method that causes Vitamin C to have the highest loss and by what percent is is lost
Boiling
75%
Name 2 food that Thiamine (Vitamin B1) is lost in and how
Meat - Losses during heat treatment varies with the type and part of meat and the water and fat content
Milk - Degradation about 10%
What food additive caused destruction of folate?
Sodium Nitrite used in some cured products
Name the most soluble vitamin during thermal processing and give the pH
Pantothenic Acid (Vitamin B5)
pH levels of 5-7
Name the most stable water-soluble vitamin
Niacin (Vitamin B3)
How are proteins denatured?
DO denatured amino acids still provide nutrient value if eaten?
Denatured by cooking
Heart - disrupts hydrogen bonds and non polar hydrophobic interactions
pH
Denatured amino acids still provide nutrient value if eaten
Give 3 public health issues with food processing
Salting, pickling & smoking linked to increase cancer mortality due to formation of carcinogenic substances such as nitrosamines.
Salt-preserved /salted foods increases sodium intake associated with stomach cancer and high blood pressure/cardiovascular disease
Limit added salt intake to <6 (2.4 g sodium)/day
Give a public health issues on eating meat?
For people who eat meat, eat no more that moderate amounts or red meat, such as beef, pork and lamb, and eat little, if any, processed meat
How does food processing contribute to health?
Helps ensure population can access sufficient food, wider variety, choice
Keeps food microbiologically safe
Maintains taste/flavour
Name the 4 categories processed foods are classified by
Unprocessed or minimally processed foods
Processed culinary ingredients
Processed foods
Ultra-processed foods
Give 3 ways food processing can promote well-being
Food processing technologies can promote the health and wellness of consumers
Major focus will be on ways to use the technologies to address the chronic diseases facing the population
Evolving food processing approaches could encourage and enhance healthy lifestyle
Explain 3 ways food processing technologies and innovations may benefit consumer
Reduce Allergy - Plant modification to reduce antigen exposure, Prevention of allergic responses
Improved food safety and reduces food waste - Smart packaging materials, reduced landfill waste
Reduce salt intake - Altered salt crystals structures such as micro crystallization provides flavour and food quality while reducing excessive salt intake
