Brainscape's Knowledge GenomeTM

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


See full index

Food Packaging > Natural Polymers > Flashcards

Natural Polymers Flashcards

You may prefer our related Brainscape-certified flashcards:
Gourmet Food flashcards
1
Q

Common natural polymers: (6)

A

cellulose, lignin, starch, chitin/chitosan, protein

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

Other less common natural polymers: (4)

A

alginic acid
hyaluronic acid
xanthum gum
curdlan

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

What does the traditonal viscose processing method of cellulose involve?

A

dissolve pulp with NaOH + CS2 -> used to spin fibre

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

major problem with procesesing cellulose:

A

difficult to process in solution or as a melt

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

cellulose is made of repeating ______ units

A

B 1,4 glucan

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

What are some new cellulose solvents? (4)

A

NMMO
DMAc
Ionic liquid
NaOH/urea aqueous solvent

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

Starch is made of what monomers?

A

a 1,4 glucan (and a-1,6 glucan)

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

the 2 forms of starch:

A

amylose (linear)

amylopectin (branched)

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

characteristics of starch: (2)

A

gelatinization

poor wet mechanical property

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

chitin is made of what units?

A

N-acetylglucosamine units connected by B-1,4 linkages

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

Good source of natural chitin:

A

arthropod exoskeletons

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

How is chitin converted to chitosan?

A

deacetylation (>55%) using NaOH

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

Good properties of chitin & chitosan:

A

antibacterial, antiinflammatory

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

How are amino acids polymerized into proteins?

A

condensation reactions -> form peptide bond

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

the general structure of an amino acid:

A 
amino end, carboxyl end
R group (variable)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a bioplastic?

A

biopolymer that can be shaped/molded via plastication or crosslinking

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

problems with conventional plastics (synthetic) that bioplastics aim to address: (4)

A

limited recycling
limited landfill space
toxins from incineration
fossil fuel consumption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

some bioplastic examples (and their sources)

A 
PLA (Polylactic acid) from corn
PHA from bacteria
soy/casein/corn protein
Cereplast - starch based
SoyOyl - veg oil based
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How can bioplastics be combined with conventional plastics?

A

composite materials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Are all bioplastics biodegradeable?

A

No:

soy oil plastics, soy protein-formaldehyde, casein-formaldehyde are NOT biodegradeable

21
Q

What is a material that is biodegradeable but not renewable?

A

PCL (polycaprolactone)

and other biodegradeable synthetics

22
Q

biopolymers that are both renewable + biodegradeable:

A 
PGA
PLA
soy protein plastics
starch based plastics
PHA
23
Q

advatnages of biopolymers: (6)

A 
renewable feedstock (raw materials)
domestically grown
CO2 neutral
biodegradeable
biocompatible
energy-saving (lower process temp)
24
Q

disadvantages of biopolymers: (4)

A

more $$$
low mechanical properties
lower functional temperatures
less durable in harsh environments

25
Q

proteins are usually ____polymers

A

hetero

26
Q

T/F: starch based polymers are more diverse than protein based

A

false: proteins have very large variety of polymer network structures -> large spectrum of chem functionalities

27
Q

Common plant proteins (4)

common animal proteins (4)

A

corn zein
wheat gluten
soy protein
sunflower proteins

caseins
whey
gelatin/collagen
myofibrillar

28
Q

Wheat gluten is majorly sourced from where?

A

starch industry (co-product)

29
Q

advantages of gluten based materials:

A 
good film formation
high availability + low $
biodegradable/nontoxic
adhesive properties
high gas barrier + perm selectivity
30
Q

How does energy usage and CO2 emissions for wheat gluten compare to LDPE?

A

over 5x less!

31
Q

What happens to the barrier properties of wheat gluten if Aw is increased?

A

increases by thousands of times!

very poor barrier at high moisture

32
Q

Increasing Aw will (increase/decrease) the gas permeation selectivity of wheat gluten

A

increase

better selectivity at high moisture

33
Q

downside of wheat gluten materials (2)

A

poor water resistance

poor mechanical properties

34
Q

Where is barley protein obtained from

A

byproduct of starch or beta glucan processing

35
Q

How is barley protein made into a film?

A

barley protein + glycerol
hot pressing (>100C, 20MPa, 10 min)
forms barley protein film

36
Q

How can properties of protein bioplastics be modulated? (3)

A

crosslinking
lamination
composites (mix with other materials)

37
Q

What is a common crosslinking agent for protein bioplastics? What does it achieve, and what is a concern?

A

formaldehyde
improve mechanical and barrier properties
concern: toxicity

38
Q

How is lamination used to enhance protein bioplastics?

A

apply onto another material (paper) as coating agent; paper acts as support
coating will provide functionality: give MAP/selectivity properties to paper, or controlled release of antimicrobial compounds, etc

39
Q

What are some natural antimicrobial compounds that could be emitted by protein bioplastics?

A 
carvacrol
menthol
cinnamaldehyde
AITC
Eugenol
40
Q

How is SPI/cellulose nanocrystal composite made?

A

cotton pulp -> sulfuric acid -> cellulose nanocrystals
combine with SPI (soy protein isolate) + glycerol
hot pressing
cellulose/soy composite material

41
Q

the molecular structure of natural polymers:

A

fibre (made of microfibrils connected by interfibrillar tie molecules)
made of crystalline regions + amorphous regions

42
Q

What are natural polymer nanocrystals used for? (4)

A

reinforces mechanical properties
improves barrier properties
stabilizes food emulsions
swelling properties

43
Q

polyurethane can be reinforced with _____ nanocrystals

A

starch (or starch + cellulose)

44
Q

____ nanocrystals are used as a Pickering emulsion stabilizer

A

cellulose

45
Q

biopolymer microspheres can be used as a:

A

edible delivery vehicle

46
Q

What can be used to make edible delivery vehicle?

A

barley protein
alginate-whey
oat protein gels

47
Q

Why are edible delivery vehicles useful? (2)

A

protect enzymes/probiotics/vitamins from harsh stomach condition
or controlled release of some active substances

48
Q

How are micro/nanofibres produced?

A

electrospinning

polymer solution ejected through syringe/spinneret connected to high voltage - draws out long thin threads

49
Q

Uses for electrospun micro/nanofibres: (2)

A

gas sensors for food safety

‘smart’ food preservation (atmosphere, pH, light, temp)

Food Packaging (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions