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NUTR217 Food Fundamentals > Food Preservation > Flashcards

Food Preservation Flashcards

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1
Q

% of food waste and loss in that type of food

  1. cereals
  2. dairy products
  3. fish and seafood
  4. fruits and vegetables
  5. meat
  6. oil seeds and pulses
  7. roots and tubers
A
  1. 30%
  2. 20%
  3. 35%
  4. 45%
  5. 20%
  6. 20%
  7. 45%
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2
Q

% of the world’s food that is lost in food spoilage

A

25%

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3
Q

4 characteristics of food spoilage

A
  1. decomposition, loss of nutrition value
  2. consumption (by rodents, microorganism, flies)
  3. obvious and detectable (due to decrease quality: odour, texture, appareance,taste)
  4. most perishable food = high in protein and water
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4
Q

3 changes that lead to food spoilage

A

physical (water loss, separation)
chemical (enzymes, naturally present)
biological (yeasts, bacteria, molds)

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5
Q

3 characteristics of yeast (biological)

A
  1. fungus (plants that lacks chlorophylls)
  2. ferment sugars (CHO= CO2 and alcohol)
  3. used for producing food products (bread, beer..)
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6
Q

3 characteristics of bacteria and molds

A
  1. they can produce toxins
  2. molds are visible but not bacteria
  3. bacteria can ferment sugars
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7
Q

4 techniques to destroys/inhibit growth of yeast, bacteria, molds

A

refrigerate, drying, boiling, curing (high salt/sugar)

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8
Q

the enzymes that catalyse reactions are categorized by what (2)

A
  1. substrate
  2. mode of action:
    protease (proteolytic enzyme): proteins (AA)
    lipase: lipids= FA + glycerol
    carbohydrase: CHO= glucose
    others ex: polyphenol oxydase (PPO)
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9
Q

why fish and sea food are more vulnerable to food spoilage than meat

A

it contains more protease (enzyme that transforms protein in AA) so it is a chemical change that leads to food spoilage

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10
Q

2 nonenzymatic reaction (chemical)

A
  • oxidation of fat (lypase can breakdown in triclyceride and create off flavor + can lead to cancer)
  • maillard reaction
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11
Q

2 elements of maillard reaction

A
  1. may occur with long storage of non-fat dry milk (lactose + protein= nonenzymatic browning)
  2. bioavailability of proteins decrease: AA involved in reactions not readily released during digestion
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12
Q

3 types of physical change

A
  1. evaporation/dehydration
  2. separation
  3. damage/mechanical: bruising, tearing of tissues
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13
Q

3 types of separation

A
  1. drip loss (ex: when you put something in the freezer, the juice that you lost when you rechauffe the product will create a less moist product)
  2. emulsion breakdown (ex: mayonnaise, after a moment, the composition will separate into its original form)
  3. syneresis (gel): ex: a pouding in the fridge for 2 weeks, the liquid squeeze out
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14
Q

6 methods of food preservation

A
  1. high temperature to destroy microorganisms and enzymes
  2. low temperature to control microorganisms growth
  3. removal/tying up of moisture to control microbial growth (salt, sugar.. so there is less water available for microorganisms)
  4. additional of chemical preservatives to inhibit microbial growth
  5. keeping out microorganisms
  6. ionizing radiations to destroy microorganisms and control enzyme activity
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15
Q

3 characteristics of drying

A
  1. removes water in food
  2. inhibits growth of microorganisms (because bacteria and yeast need a minimum of % of moisture to survive)
  3. sun-drying or commercial drying
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16
Q

% of moisture that bacteria and yeast need to survive

A

bacteria and mold: 15%

yeast: 20%

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17
Q

3 examples of sun-drying

A
  1. pandanus (pohnpei)
  2. seaweed (ainu)
  3. fish (gwich’in)
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18
Q

4 types of commercial drying

A
  1. conventional (uses heat): drying room, tunnel drying, spray drying, drum drying)
  2. vacuum (uses low pressure) so the boiling point of the water is very low
  3. osmotic (uses strong syrop)
  4. freeze-drying (ice crystals vaporize)
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19
Q

3 characteristics of curing (don’t kill the microorganisms but make it really hard for them to develop)

A
  1. preservation with use of salt and drying
  2. nitrates, sugar, spices may be added
  3. meat and fish may also be smoked (added flavour and preservation)
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20
Q

2 characteristics of pickling

A
  1. preservation by acidification (add acid/vinegar OR fermentation)
  2. spices/herbs may be added for flavor
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21
Q

what is edible coating

A

a thin layer of edible material (CHO,PRO or FAT) used on fruits, vegetables, cheese, nuts, dried fruits, processed meat..

22
Q

4 advantages of edible coating

A
  1. increases shelf life (barrier to moisture, O2,CO2, volatile aromas)
  2. imrpoves handling (less breaking/damage)
  3. improves appearance by increasing gloss, colour
  4. vehicle for added ingredients (flavors, antioxydant,antimicrobials)
23
Q

3 types of food for canning

A

fruits, vegetables and meats

24
Q

2 steps process of canning

A
  1. food packed into sterilized containers and sealed
  2. containers canned/ heated to destroy microorganism and enzymes (extended boiling/heating to temperature much higher than regular boiling point)
25
Q

2 methods of canning

A
  1. boiling water process (good for low pH items)
  2. pressure canning (for pH higher than 4,5 boiling at higher temperature under pressure, to destroy Clostridium botulinum)
26
Q

4 characteristics of canning of high acid foods

A
  • for fruits and tomatoes (pH lower than 4,5)
  • safely canned in a boiling water bath
  • heat resistance of microbes is decreased by the acidic pH: can be destroyed in reasonable processing times
  • surviving organisms will not grow in acidic environments
27
Q

5 low acid foods ingredients for canning

A 
vegetables
meat
fish
milk
poultry
28
Q

2 characteristics of canning for low acid foods

A
  1. requires relatively high processing temperatureto destroy all spore-forming organisms, particularly C. Botulinum
  2. requires a pressure canner where the temperature is higher than usual boiling point of water can be achieved
29
Q

3 heat preservation

A
  1. boiling: simplest method, 10 minutes
  2. pasteurization: liquids are heated to a certain temperature for a certain period of time, killed bacteria/mold/yeast
  3. ohmic heating: electrical current passed through food, generating heat that destroys microorganisms, for liquid eggs/fruit juices
30
Q

what refrigeration slows down

A

biological, chemical and physical reactions that decreases the shelf life of food

31
Q

which food are mostly refrigerated

A

high water content food

32
Q

temperature of refrigeration

A

just above freezing to less or equal to 4degree

33
Q

3 characteristics of freezing

A
  • -18degree or lower= least damaging to flavor
  • water unavailable to microorganisms
  • slows chemical and physical reactions (enzymes..)
34
Q

5 problems of freezing

A
  1. reactions still continue (oxygen present), so shorter life than canned goods
  2. recrystallisation
  3. cell rupturing
  4. fluid loss
  5. freezer burn
35
Q

what happens to the crystal if its rapidly frozen

A

ice crystals are small and numerous, mostly intracellular= give superior food quality

36
Q

what happens to crystal if it is slowly frozen

A

ice crystal are large and fewer in number, form in extracellular spaces
* upon thawing, loss of juices occurs

37
Q

what is freezer burn and why does it happen

A

dehydration on the surface of frozen food (white or greyish patches)
- inadequate packing : water evaporate and may recrystallize on surface of food

** quality will never be the same, consider food spoilage

38
Q

oxidation of polyphenolic substances in plant tissues by _______ may occur during ______.
what is its result

A

polyphenolase
frozen storage
result in undesirable browning

39
Q

why blanching vegetables (2)

A
  1. destroys enzymes that cause browning (oxidation of polyphenolic substances
  2. it inhibits the ascorbic oxidation by inactivating ascorbate oxidase
40
Q

what is the number one cause of nutrient

A

oxidation of ascorbic acid

41
Q

when ascorbic acid is oxidize

A

during frozen storage

42
Q

5 changes in colloidal substances during frozen storage

A
  1. retrogradation of starch + syneresis
  2. toughening of cellulose
  3. breaking of emulsion
  4. nutrition value: no significant effects on macronutrients unless food is kept for a long time
  5. vitamins and minerals: 4% loss in drip (vit C and vit B (especially folate)
43
Q

why blanching before freezing, using boiling water or steamed (3 positive points, 1 negative)

A
  • destroys enzymes responsible for the development of off flavors
  • controls undesirable changes in colour and texture
  • inhibits conversion of bright green chlorophyll to olive green pheophytin
  • but destroys some vit C and folate
44
Q

what is irradiation

A

treatment of food with ionizing radiation

45
Q

what is the main goal of irradiation

A

reduce microbial load on spices and dehydrated seasoning preparation, meaning it destroys bacteria, yeasts, molds which cause food to spoil

46
Q

2 advantages of irradiation

A
  1. control insect in wheat, flour and whole wheat flour

2. increase shelf life by preventing sprouting or germination in potatoes and onions

47
Q

ingredients approved by Health Canada for irradiation (8)

A

potatoes, onion, wheat, whole wheat flour, flour, whole and ground species, dehydrated seasoning preparation and fresh and frozen raw ground beef

48
Q

what is aseptic packaging

A

sterilized, packed and sealed in sterilized container under sterilized conditions
can sit at room temperature

49
Q

example of food for aseptic packaging (4)

A

juices boxes, pudding, baby foods, UHT milk…

50
Q

what is MAP

A

composition of surrundings air is change (usually decrease in O2, increased CO2 but depend on food products)

51
Q

3 examples of food that use MAP

A

fruits/vegetables, meat/poultry, baked goods

52
Q

what is hermetically sealed

A

foods that have been packaged airtight by a commercial sealing process

NUTR217 Food Fundamentals (10 decks)

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