FOOD PRESERVATION 2 Flashcards

1
Q

what is pickling

A

preserves foods through acidification (acidity controls microbial growth)

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2
Q

what is used to pickle

A

vinegar (acetic acid); other wear organic acids, like lactic and citric

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3
Q

what are the two steps of canning

A

preparation + heating

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4
Q

what does preparation mean

A

packing food and liquid into the container

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5
Q

describe headspace

A

small amount of air left at top after canning preparation; required to ensure vacuum seal

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6
Q

describe heating

A

boiling water processing; needed for low-acid foods

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7
Q

how does canning destroy and prevent growth of microorganisms

A

through heating and removal of O, and sometimes addition of acids

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8
Q

what are low-acid foods and what are high-acid foods

A

low acid foods have a pH higher than 4.6
high acid foods have pH lower than 4.6

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9
Q

what are the two methods of cold preservation

A

refrigeration + freezing

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10
Q

describe refrigeration

A

slows down biological, chemical and physical rxns

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11
Q

describe freezing

A

least damaging preservation method in terms of flavor, nutrient content, and texture

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12
Q

what does freezsing do to microroganisms

A

makes water unavailable to microorganisms to grow, but still some O present

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13
Q

describe relationship between fat content and shelf life

A

higher fat content = lower shelf life due to rancidity

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14
Q

what are the four problems with frozen foods

A

freezer burns, cell-rupturing, fluid loss, recrystallization

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15
Q

describe freezer burn

A

caused by moisture loss (via sublimation) resulting in altered texture, appearance, and flavor; due to improper packaging or prolonged freezing

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16
Q

describe cell-rupturing

A

water expands upon freezing; large crytals can rupture food’s cell cells causing inferior texture

17
Q

should foods with higher water content be frozen

18
Q

describe fluid loss

A

frozen meat loses water when thawed, which can result in drier texture

19
Q

describe recrystallization

A

small ice crystals melt and freeze as larger crystal, which affects texture; occurs with temp. fluctuations; more crystals = worse quality of food

20
Q

describe boiling

A

10 min of boiling kills/inactivates most microroganisms

21
Q

describe ohmic heating

A

electrical current passed through food to generate heat to destroy microorganisms; used in juice preservation

22
Q

describe pasteurization

A

foods heated to specified temp for a certain period of time to destroy microorganisms

23
Q

describe milk pasteurization

A

145 F for 30 min

24
Q

describe high temp short time pasteurization varaiation

A

161 F for 15 seconds

25
describe ultra high temp pasteurization variation
temps >280 F for 2 seconds
26
whats irradiation
cold pasteurization; food exposed to ionizing energy source, like gamma rays, X-rays, or electrons
27
does irradiation make food radioactive
no
28
what do free radicals do
damage DNA of microorganisms
29
what is irradiation used in
wheat flour, potatoes, spices, meat, shellfish, poultry, eggs
30
what are some concerns with irradiation
possible nutrient loss, environmental hazards, and free-radical production
31
what are the labeling requirements for irradiation
"treated with radiation"
32
describe pulsed light
food exposed to intense, brief flashes of light
33
what does pulsed light do to bacteria
disrupts bacterial cell membrane, but not those of the surrounding foods damages bacterial DNA
34
whats high-pressure processing (HPP)
uses high pressure (<50,000 psi for 15 min) to deactivate microorganisms and enzymes responsible for deterioration
35
when is HPP used
for juices, sauces, ready-to-eat meats
36
how are macros, fat-soluble vitamins, and minerals effected by processing
relatively unaffected
37
what vitamins are most susceptible to loss after cooking in liquid
water-soluble vitamins (c and b0
38
is nutrient data for cooked foods limited
yes
39
do unprocessed foods undergo nutrient loss
yes