Exam Review II

Question 1

1. Define food processing

2. What are concerns
3. What are reasons

Answer 1

1. the activities applied to primary agricultural products
2. loss of nutrients,exposure to harmful substances, impact on environment
3. reasons include
   
   • extend the availability beyond the season and location it is grown
   • improve nutritonal value of food
   • improve food safety
   • for convenience

Question 2

food processing examples

Answer 2

• removal of unwanted outer layers
• chopping
• mincing
• emulsification
• deep frying
• mixing

Question 3

Preservation

Answer 3

• 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

Question 4

Preservation - chilled storage

Answer 4

• 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
  *

Question 5

preservation - freezing

Answer 5

• 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

Question 6

Fresh vs frozen

Answer 6

• 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

Question 7

preservation: high temperatue techniques

Answer 7

• 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

Question 8

Nutritional impact of pasteurisation

Answer 8

• 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

Question 9

preservation: sterilisation -> canning process and nutrient losses

Answer 9

• 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

Question 10

preservation: irradiation

Answer 10

• 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

Question 11

preservation: drying

Answer 11

• 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

Question 12

preservation: drying methods and nutrient concerns

Answer 12

• 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

Question 13

preservation: salting

Answer 13

• salting often used on fish, meats and veg
• high salted food consumption can increase risk of gastric cancer and hypertension

Question 14

preservation: smoking

Answer 14

• 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.

Question 15

preservation: sugar and other chemicals

Answer 15

• 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

Question 16

preservation: pickling

Answer 16

• two methods of pickling
  
  • lacto-fermentation pickling - lactic acid
  • vinegar pickling - acetic acid
• Health effects
  
  • some are associated with increased gastric cancer risk
  • vinegar may be beneficial for glycaemic affect and immune system

Question 17

Food processing: milling

Answer 17

• 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

Question 18

Food processing: milling

• Nutrients in whole grains

Answer 18

• endosperm
  
  • starch, vit B2 and B5, aleurone
• germ
  
  • unsat fats, vitamins B1, B2 and B6
  • high in protein
  • minerals eg potassium
• bran
  
  • fibre, lignin, Mg, Ca, Na etc

Question 19

wholemeal vs refined flour

Answer 19

• white flour has significant losses of vitamins, minerals, dietary fibre etc and increases glycaemic index
• Wholegrain/wholemeal contain prebiotic substances

Question 20

processed foods contain potentially harmful substances such as

Answer 20

• acrylamide
  
  • forms when starchy foods are cooked or processed
  • cancer association
• advanced glycation end products (AGEs)
  
  • promote oxidative stress and inflammation
  • eg beef, cheeses, poultry
• Bisphenol A (BPA)
  
  • used in the lining of some food and beverage packaging
  • is an endocrine disrupter
• Phthalates
  
  • plasticisers often in commercial cling wraps and other plastics
  • endocrine disruptors
  • linked to obesity ,heart disease, cancer
• HCAs and PAHs
  
  • ​chemicals formed when muscle meat, including beef, pork, fish, or poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over an open flame
  • HCAs form when amino acids, sugars and creatine react at high temp
  • PAHs form when fat and juices from meat drip onto fire