Exam Review II Flashcards
1
Q
1. Define food processing
- What are concerns
- What are reasons
A
- the activities applied to primary agricultural products
- loss of nutrients,exposure to harmful substances, impact on environment
- reasons include
- extend the availability beyond the season and location it is grown
- improve nutritonal value of food
- improve food safety
- for convenience
2
Q
food processing examples
A
- removal of unwanted outer layers
- chopping
- mincing
- emulsification
- deep frying
- mixing
3
Q
Preservation
A
- food is biological material that will decay with time
- preservation techniques include
- use of low temps
- low temperatures slow the rate of food decay reactions
- chilled storage (-1 to 8 degree) or freezing
- or high temps
- irradiation
- drying or with salt, sugar and other chemicals
- use of low temps
4
Q
Preservation - chilled storage
A
- cooling food to below room temp slows rate of decay reactions
- -1 to 1 degree for fresh meat and fish
- 0 to 4 degree for milk products and baked goods
- nutrient content is not significantly reduced provided the food is consumed within its shelf life
*
5
Q
preservation - freezing
A
- very little effect on nutrient content
- some fruit and vege are blanched before freezing to inactivate enzymes and yeasts that would cause spoilage even in freezer
- this can cause some vit C loss
- Harvested produce can take days to be sorted, transported and distrubuted to stores = slow loss of vitamins and minerals
- Avoid frozen dinners as they have undergone further processing
6
Q
Fresh vs frozen
A
- green beans
- frozen had 2x vitamin C
- carrots
- canned carrots more beta-carotene
- broccoli
- frozen broccoli 92% less vitamin C than fresh
- slow loss of vit c in the fridge
- spinach
- frozen higher in vit C
- peas
- frozen higher in vit C
7
Q
preservation: high temperatue techniques
A
- blanching
- briefly immersed in boiling water or steam
- inactivates enzymes
- often loss of water soluble vitamins occurs
- pasteurisation
- destroys bacteria and extends shelf life
- eg milk - heated to high temp of 72C then cooled immediately to 4C or less
- unpasteurised cows milk is illegal to sell in australia due to the risk of foodbourne illness resulting
- sterilisation
- high temp for sufficient duration to completely destroy microbe viability
- nutrient content ramins for several months to years
- eg canning or ultra high temperature treatment
8
Q
Nutritional impact of pasteurisation
A
- Most of vitamin C is lost during handling, pasteurisation and packaging of milk
- small loss of some nutrients such as thiamine, cobalamin etc
- however the effects of pasteurisation on nutritional value of milk is negligible compared to health risks without it being done
9
Q
preservation: sterilisation -> canning process and nutrient losses
A
- food is processed and stored in airtight container
- a number of different methods may be used to prevent spoilage before and during containment eg freezing, boiling, drying etc
- often packages in tinplate or aluminium containers
-
all are sterilised by heating during manufacturing
- no microbe spoilage occurs in canned products
- large tinned food consumption increases the level of tin consumed
Nutrient losses
- vegetables loss carotenes, vit C and B vitamins
- meat loss of thiamin and complete loss of riboflacin
- UHT milk loss of B group vitamins
10
Q
preservation: irradiation
A
- food is exposed to ionising radiation
- eg gamma rays or high energy electron beam or powerful xray
- Rays pass through the food, but don’t heat it, and kill bacteria
- irradiation (measured in kGy) has set ranges to maintain health safety
- A food which has been irradiated must be labelled as such
11
Q
preservation: drying
A
- old traditional method of preservation
- Bacteria and other micro-organisms within the food and from the air need the water in the food to grow.
- Drying effectively prevents them from surviving in the food. It also creates a hard outer-layer, helping to stop micro-organisms from entering the food.
- e,g, bananas, apples, beef jerky
12
Q
preservation: drying methods and nutrient concerns
A
- methods
- solar drying - suns energy
- oven drying
- electrical drying
- freeze drying - commercial method
- nutrition
- dried foods are more energy dense
- cooking dehydrated foods in water causes nutrient loss into the water
- vit C and B6 loss
- pro-vitamin A and C destroyed by heat and air
13
Q
preservation: salting
A
- salting often used on fish, meats and veg
- high salted food consumption can increase risk of gastric cancer and hypertension
14
Q
preservation: smoking
A
- process of flavouring, cooking or preserving foods by exposing it to smoke from burning or smouldering material, such as wook
- meat and fish common
- Smoking food produces polycyclic aromatic hydrocarbons (PAHs) which are potentially carcinogenic.
15
Q
preservation: sugar and other chemicals
A
- sugar is used to preserve fruit by creating an osmotic gradient that impedes microbe processes
- various other chemicals may be used
- usually in combination with other methods such as dehydration, pasteurisation
17
Q
Food processing: milling
A
- Grains can be cooked in their whole form with water (eg brown rice) or milled in flour (eg breads, pastas etc)
- Wholemeal flour - all elements included
- white flour - formed only by crushing the endosperm
