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FOOD QUALITY & CULTURE > Food Preservation Methods > Flashcards

Food Preservation Methods Flashcards

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1
Q

what is food preservation

A

the science of extending the shelflife of food to maintain its nutritional quality and avoid the growth of unwarned microorganisms

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2
Q

how is shelf-life labeled

A
  1. date of minimum durability (best before)

2. expiration date (use by)

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3
Q

what is food spoilage

A

undesirable changes occurign in food due to airt, heat, light or moisture that motivates microorganism growth

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4
Q

how is food mainly spoilt

A
  1. microorganisms
  2. enzymes
  3. insects
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5
Q

two ways bacterial infections are caused

A

infections

intodications

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6
Q

carrier issues

A

healthy subjects hosting pathogens working in food industry might contaminate/transmit pathogens

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7
Q

main cause of food posioning?

A

cross contamination

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8
Q

how can one avoid cross contamination

A

avoid letting raw meats/animal products/raw veggies touch other food

always clean utensils/board

clean worktops with detergent

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9
Q

types of bacteria

A

cause spoilage
can be useful (health, fermentation)
dangerous (toxins/pathogens)

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10
Q

3 main sources of food contamination

A
  1. raw matieral I.e. meat, egg shells, fresh milk
  2. environment: storage of food, breeding, cultivation
  3. manufacturting practice: failure of HAACP
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11
Q

types of preserved foods

A
  1. stored products [frozen/dried/canned]
  2. semi preserved products [pasteurized, chilled]
  3. processed [fermented, salted, seasoned, smoked]
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12
Q

methods of preservation

A

phsyical
chemical
biological (fermentation)

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13
Q

physical preservation methods

A 
refridgeration 
freezing 
modified atmosphere packing 9MAP)
high  temperature 
pasteurization 
sterilization 
packaging (tetrapak/aspeptic)
dehydration 
concentraiton
lyophillization (free drying)
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14
Q

chemical prservation methods

A 
salting
sugaring
vegetabale oils
vingegar
ethyl alcohol
food smoking/liquid smoke
use of preservatives
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15
Q

explain the process of refrigeration

A
  • 1 to 8.C
    1. food is refrigerated during transport/storage and sold at room temp (fruit/veggies)
    2. food fully sold/distributed in fridge
    i. e. meat, milk, fish, salads, etc.
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16
Q

explain the process of: CA (controlled atmosphere)

A

oxygen kept at 5%
carbon dioixe at 1-3$
temperature dependign on food

used to extend post-harvest life of fruits

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17
Q

how does CA extend the harvest life of fruits

A
  1. reducing oxygen= reduces microbial contamination
  2. hydrating in water and creating acidic environment by carbnon dioxide= kills them
  3. inhibits enzymes/tissue metablism
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18
Q

where is oxygen icnreased in CA

A

for red meat storage to increase myoglidoin red pigment meat colour

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19
Q

why is adding oxygen bad to food

A

promotes enzymatic/chemical oxidation
activates beta-carotene degradation
substrate of respiration of plant/microbial cells

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20
Q

explain the process of: MAP (modified atmosphere packaging)

A

extends shelf life by creating barrier using packaging (to gas/contaminants) or vacuum packaging

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21
Q

example of MP matieral

A

polyvinyl chloride
polypropylene
polyethylene
vacuum packaging

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22
Q

where/which foods is MAP used

A

fresh apsta
baked goods
meats
frest cut fruts coffee

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23
Q

proces of vaccum packaging

Study These Flashcards
A

pressure put below atmopshreic value

  1. stored in CRYOVAC (waterpoof vaccum)
  2. bags sealted under vaccum
  3. pacakge immersed in water at 90C
  4. hearable film adheres to film
24
Q

types of freezing methods

Study These Flashcards
A

flash freezing
industrial flash freezing
deep freezing

25
explain flash freezing
food quickly frozen at extreme cold temperature between -0.5/4 degrees which stops enzymatic reactions when water is solidifed is fast to create smaller icecrystals that don't damange the food
26
what is industrial flash freezing
forms smaller chrystals at fast temprature
27
how does flash freezing occur
sample placed in sample with liquid nitrogen/dry ice + ethanol or product pressed between 2 plates at -40/50 c (spinach cubes) or bulk subjected to jet of air in tunnel/freezing cells (peas, carrots) or product sealed in wterpoof packaged in placed in non freezable liquids (poultry) or direct use of freezing product
28
what is the cold chain?
how products are frozen from raw matieral to consumers to fridege/freezer in the supply chain in : procurement, trasnport, storage and customer retail
29
cons of just deep freezing
creates larger chrystals that when thawing, might damage the nutritional properties of food
30
high temperature methods
blanching | pasteurization
31
what is blanching
slighly cooking food (veggies) to inactivate enzymes/slow them down and: clean surface from dirt and mold brighten colour make it easier to cook/pack
32
what is pasterurization
heat prevents bacterial flora to ferment | other proesses often used with it (chemicals, vaccuum packaging, freezing)
33
types of pasteuriziation
high temperature (70-75 c for few minutes) low (60-65 for 30 minutes) HTST: high temperature and fast time (liquid for few seconds)
34
how is milk pasteruized
HTST applied isuing steel plates | kills lactophillus bacteria which need sto be added in after pasteurization for lactose fermentation
35
two types of milk
extended shelf-life milk (extremment HTST) raw unpasteruzied milk (special outlets and filtering rules) pasteurized
36
what is sterilization
kills all microboial forms to can them/jar them
37
how does commercial sterilization occur
temperature related to acidity of the food for canning (if pH lower than 4.5 100 c used, if higher: 115-120) especially for meat products
38
compromise in sterliziation
high temperature: microbio safety | moderate temp: product quality
39
method of sterilization
1. pressure cookers used (autoclaves) 2. steam injected at high temperature 3. indirect UHT (ultra high tempt), direct UHT 4. cooling 5. aspeptive pacakging in sterile containers
40
packaing methods
tetrapak | aspeptic packaing
41
tetrapak composition
paper (75), plastic (20), aluminum (5)
42
aspeptic packaging process
sterilized food placed into sterile containers superior nutritional quality but shorter duraiton and prevents additive use must be santiized by hydrogen perodixe vapour (which is ecological as split into oxygen and water)
43
dehydration method
water encourages micro/enzyme activity: hence: total dehydration for milks/cereal partial dehydraiton for tomato juice/fruitjuise often combined by other tech
44
methods of dehydration
1. cold 2. hot (special evaporater machines or industrial ovens) 3. concentration 4. lyiphillization
45
pros of dehydration
long shelf life reducton of volume and weight lower tranpsort costs
46
concentration method aim
reduce foods weight to make less expensive, easier to store and easier to transport
47
dehydration types
``` evaporation cyroconcentraion (lowers coneglation point) membrane technology (filtration and reverse osmosis) ```
48
lyophillization method
freeze drying method; preserves biomatierals for extended perio to be used at room temperature using the process of sublimation (solid to vapour state)
49
proces of lyophilliziation
rapid freezing of food at -30/40 and then dehydraiton by sublimiation in vaccum
50
common food types lyophilized
``` coffee fruit and juice veggies meat fish eggs dairy ```
51
salting process
``` dry salting (fish, sausages) wet salting (for smoking, fridge, saline solutions, etc. ) ``` salting= kills pathogens due to NaCl dehyrating them
52
sugaring
use of sucrose to dehydrate microrganisms
53
vegetable oils
protect food from air (like olive oil)
54
issue with oils
clostridium bacteria can still develop anaerobically so contamination still possible
55
food smoking process
exposesd cured meats, fish and dairty to aromatic wood to: 1. increase palatabiltiy 2. presreve food
56
types of chemical preservatives
``` sulphates sorbic acid ntirates benzoic acid salts ascorbic acid ```

FOOD QUALITY & CULTURE (17 decks)

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