Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

FOSC302 > High Pressure > Flashcards

High Pressure Flashcards

1
Q

type of processing for:
solid foods
liquids

A

solid: batch
liquid: semi continous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

machinery required

A

pressure vessel and pressure generator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe process

A

packaged food is loaded in and the container is sealed, transmission fluid is pumped in until pressure is reached, valves are then shut for the desired time period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

why is water important

A

it is virtually incompressible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe process

A

packaged food is loaded in and the container is sealed, transmission fluid is pumped in until pressure is reached, and valves are then shut for desired time period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the isostatic principle

A

pressure is transmitted instantaneously and uniformly throughout the sample
-independent of volume and geometry of the sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe process

A

packaged food is loaded in and the container is sealed, transmission fluid is pumped in until pressure is reached, and valves are then shut for the desired time period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe process

A

packaged food is loaded in and the container is sealed, transmission fluid is pumped in until pressure is reached, and valves are then shut for the desired time period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the isostatic principle?

A

pressure is transmitted instantaneously and uniformly throughout the sample
-independent of the volume and geometry of the sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

why is LeChateliars principle important

A

reactions that result in a volume decrease are stimulated
-those causing a volume increase are disrupted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what happens if bacteria tries to grow under pressure

A

bursts as system tried to reestablish equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what happens to inoic bonds

A

broken

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what type of bonds are favoured

A

hydrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what type of bonds are unaffected

A

covalent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

examples of covalent bonds in food

A

low molecular weight, resonsible for sensory nad nuutritional qualitity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

does the maillard reaction occur

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

examples of changes in high molecular weight molecules

A

protein, starches have altered functionality

18
Q

where is the primary site of damage in cells

A

cell membrane
-disruption in function and leakage

19
Q

what happens to the cell membrane

A

volume and cross-sectional area of bi-layer is reduced

20
Q

what can happen to enzymes

A

change on active site conformation
alteration of intramoleuclar structure

21
Q

steps of DNA replication that are disrupted by pressure

A

replication and transcription

22
Q

are eukaryotes or prokaryotes more resistant

A

eukaryotes

23
Q

which is the most resistant stage of growth

A

stationary more than exponential

24
Q

what substrates confer protection

A

proteins, lipids and carbs

25
Q

what does a rich media supply

A

more amino acids for stressed cells

26
Q

why does pH of aqueous solutions decrease with pressure

A

electrostriction

27
Q

what temperature should be treated at

A

below ambient (2 or 10 C)

28
Q

how does applying mild heat affect the inactivation of resistant vegetative pathogens

A

more effective
-E.coli
-S.aureus

29
Q

two mechanisms for steralisation using pressure

A
  1. lower pressure and temps causes spores to germinate and they are then inactivated by pressure
  2. at higher temps a direct spore-inactivation mechanism occurs
30
Q

why are inactivation curves observed under higher temperatures for sterilisation harder to interpret

A

they dont follow first-order kinetics

31
Q

how does high pressure affect proteins

A

reversible or irreversible denaturation

32
Q

what does the denaturation of proteins depend on

A

kind of protein
processing conditions
pressure applied

33
Q

above what pressure does dentauration of proteins and inactivatoin of enzymes occur

A

300Mpa

34
Q

at pressure <300MPa what happens to enzyme activity

A

accelerated

35
Q

how are proteins denatured

A

destruction of hydrophobic and ion-pair bonds and unfolding of molecules

36
Q

what is HP used for in japan

A

surimi

37
Q

what happens to starch under HP

A

they can become gelatinised

38
Q

what pressure gelatinizes starch

A

400-500MPa
40-50C

39
Q

how are enzyme affected by HP

A

heat treatment is more affective for inactivation but used in combination with HP there may be inactivation

40
Q

commercial application of HP

A

mandarin juice: inibited mould
grapefruit juice: inhibited bitter taste
Oysters: pressure 200-300MPa 5-15 mins, 25C inactivated vibrio bacteria

41
Q

cost of HP

A

high capital cost ~10 mill
production costs ~ 4.5 c per kg/l

42
Q

advantages

A

-instant and uniform treatment independent of size and geometry
-once pressure is reach it does not require energy to hold it
-environmentally friendly
-minimal adverse effect/product stays fresh
-low running cost
-considered as natural process

FOSC302 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions