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Food Packaging > Nanomaterials > Flashcards

Nanomaterials Flashcards

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1
Q

T/F: all nanostructures are manmade

A

False; nanostructures occur naturally in many foods

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2
Q

Many food proteins are ____ structures between _____ nm in size

A

globular structures

10-100nm

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3
Q

What are some naturally occuring nanostructure molecule types in food: (3)

A

food proteins
polysaccharides/lipids (thickness)
stabilized foam/emulsions (interface)

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4
Q

Describe the nanostructure features of a stabilized foam:

A

2D nanostructure: 1 molecule thick at the interface (between the air/water or oil/water)

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5
Q

Give some examples of foods with nanoparticles (natural) (2)

A 
starch nanocrystals (custard)
casein particles in milk
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6
Q

How do starch nanocrystals change in the process of custard making

A

heated starch -> nanocrystals melt

recrystallization/hydration during coolin -> forms paste

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7
Q

Casein particles are about ____ nm in milk.

A

100nm

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8
Q

How is milk converted to a gel in yogurt production?

A 
microbe action -> lactic acid -> cleave kappa chains ends in casein
particles grow (agglomerate) -> gel structure
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9
Q

What interesting phenomena can materials display at the nano-scale? (7)

A

New properties:

high mobility
new optical properties
molecular recognition (bind/disrupt) in endocrine/DNA 
supermagnetism
superconductivity
increased reactivity
very attractive/repulsive surface charge
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10
Q

What is nanotechnology?

A

understanding/control of matter at the nanoscale (0.1-100nm) & the unique phenomena (property changes)

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11
Q

What is the scale (dimensions) for nanotechnology?

A

0.1-100nm

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12
Q

What technology is used to observe nanoparticles? (5)

A 
zetasizer
mastersizer
SEM (scanning electron microscopy)
AFM (atomic force microscopy)
TEM (transmission electron microscopy)
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13
Q

The zetasizer measures nanoparticles based on _______, reporting it as _____

A

dynamics light scattering

hydrodynamic diameter

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14
Q

Smaller particles will show (faster/slower) dynamics in a zetasizer

A

faster

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15
Q

A Mastersizer works based on the principle of _____. How does it differentiate between particle sizes?

A

laser diffraction
small particle -> more scattering
big particle -> less scatteriing

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16
Q

What is the principle of SEM?

A

electron beam directed at sample
electrons interact with sample -> produce signals
gives information on topography & composition

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17
Q

How does AFM work, and what does it provide information on?

A

gives topographical information (surface scan)

rigid cantilever with tip (Si) -> brought close to sample surface
forces will cause tip deflection (van der waals, chem bonds, magnetic, etc)

measure with beam-deflection (laser aimed down, reflects into photodiode; angle changes if cantilever moved)

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18
Q

General mechanism of TEM:

A

electron beam directed through thin sample (<100nm thick)
interacts with sample -> beam transmitted
magnify/focus onto imaging device (SED: selected electron diffraction)

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19
Q

nanotechnology is applied in what food-related products? (7)

A 
dietary supplements
nutritional additives
color additives
food procesing aids
long-life packaging
antibacterial kitchenware
fertilizers/pesticides
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20
Q

What are possible future nano food and agriculture technology? (8)

A 
interactive personalized food
edible nano wrapper
chem release packaging
extensive nano surveillance
interactive agrochemicals
nano-manipulation of seeds
synthetic biology
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21
Q

nanotechnology is involved in what sectors of food science and technology?

A

processing
product (Health/nutrition)
food safety/biosecurity
Materials

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22
Q

What is nanotech used for in materials? (4)

A

nanoparticles
nanoemulsions
nanocomposites
nano-structured materials

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23
Q

How is nanotech used in health and nutrition? (2)

A

nanoencapsulation (flavor/nutrient control, protect nutraceuticals)

engineered nanoparticulate addditives (nanosized ingredients)

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24
Q

how is nanotech involved in novel materials? (2)

A

antibacterial packaging

controlled gas permeability

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25
Q

How is nanotech involved in food safety?

A

small environmental sensors (humidity, frost, temp, light…)

self-evident shelf life labels (shows when food spoils/contaminated)

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26
Q

What is nanoencapsulation?

A

coating + entrapment of pure material or mixture inside another material (emulsion droplets < 100nm)

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27
Q

Can the core material in nanoencapsulation can be in forms other than liquid?

A

Yes: usually liquid, but can be solid or gas

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28
Q

How is the emulsion method of nanoencapsulation done?

A

disperse material in carrier solution -> coat with surfactant -> form emulsion droplets <100nm

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29
Q

Benefits of encapsulation: (4)

A

stability (heat, pH, oxidation)
taste/color (no unpleasant taste/color)
safety (mild on stomach; insoluble in gastric juice)
bioavailability (sustained release -> high absorption/bioavailability)

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30
Q

The 3 emulsion methods for nanoencapsulation:

A

extreme emulsification (high flow -> produce small particles)

phase inversion composition (add/disperse nonsolvent into material ; eventually add enough and phases change -> material dispersed in nonsolvent)

phase inversion temperature (lower temperature of emulsion -> cause phase inversion -> further dilute)

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31
Q

T/F: there is no temperature change in the extreme emulsification and phase inversion (composition) methods

A

true

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32
Q

Can nanoemulsions be used directly after forming?

A

yes - liquid form

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33
Q

What is done to convert nanoencapsulated materials into a powder form?

A

spray drying

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34
Q

How does a spray dryer work?

A

sprays fine particles (atomized) into heated dryig chamber -> dry particles collected by ELECTRODE

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35
Q

NSSL technology was innovated by _____. What is it?

A

nanosized self-assembled liquid structures (emulsions <30nm)

NutraLease ltd.

intended for nutrient/supplement delivery (coenzyme Q10, lutein, lycopene, phytosterols, vit D)

36
Q

What are nutritional concerns about coenzyme Q10 (2), and what are the benefits of being encapsulated (2)?

A
  1. not soluble in water;
  2. bioavailability is reduced by high fibre diet (-40 to 74%)

nanoencapsulation:
1. can fortify/incorporate into any water or oil-based food
2. better bioavailability (can get known % from the food)

37
Q

Nutritional significance of phytosterols

A

competes with cholesterol; high solubility and replacement of cholesterol in bile salt micelles
REDUCES CHOLESTEROL

38
Q

What is the advantage of phytosterol nanomicelles (vs normal phytosterol)

A

INCREASES CHOLESTEROL REDUCING EFFECT:

  1. improved solubility
  2. allows transport without breaking up
  3. identify large micelle membrane (bile salt) -> compete for transport (with cholesterol)
39
Q

Why would omega 3 be nanoencapsulated?

A

allows incorporation into food for health benefit, without altering the taste (fishiness), or break down of the fragile oil

(only released in stomach)

40
Q

nanoparticles can be ____ or ____ crosslinked

A

chemically

physically

41
Q

What is the most common chemical cross-linker for NP?

What are some some novel ones? (2)

A 
common: 
glutaraldehyde
novel: 
genipin
natural di/tri carboxylic acids
42
Q

What is the issue with glutaraldehyde

A

toxic

43
Q

physical cross-linked NPs are linked by _____

A

electrostatic interaction

44
Q

types of physical crosslinkers for NPs: (2)

A

anion crosslinker: TPP (tripolyphosphate)

cation crosslinker: bivalent Ca ion

45
Q

chemical crosslinked NPs are linked by _____

A

chemical bonds

46
Q

glutaraldehyde links NP using ____. Does TPP use the same mechanism?

A

chemical bonds.

No: TPP uses electrostatic interaction

47
Q

How are bioactive compounds loaded onto nanoparticles (2)

A

incorporation (during preparation)

incubation (after preparation)

48
Q

wood cellulose based polyelectrolyte NP are made of ____ and ____

A

CMC (carboxymethyl cellulose)

QC (quaternized cellulose)

49
Q

how does the proportions of CMC and QC in wood cellulose NPs affect the final NP properties?

A

more CMC -> form complex with QC in core, CMC outer = negative charged NP

more QC -> CMC in core, QC outer = positive charge NP

50
Q

More CMC in a wood cellulose NP will lead to a (positive/negative) NP

A

negative

51
Q

Which crosslinking method is better for bioactive agents?

A

physical crosslinking

52
Q

Advantages of physical crosslinking: (4)

A

no chemical crosslink reagents
mild aqueous conditions
simple procedure
suitable for bioactive agents

53
Q

What is the benefits of nano-sized ingredients and additives? (4)

A

improved texture/flavor/taste
reduce amounts of salt/fat/sugar/additives
better bioavailability/health benefit
antimicrobial (minerals)

54
Q

advantage of nano-sizing minerals:

A 
better bioavailability (nutrition)
antimicrobial
55
Q

How is nanotechnology used in chicken feed? (2)

A

nano selenium - may stop bird flu

PS nanoparticles bind bacteria (antibiotic alternative)

56
Q

real life examples of technology for food processing involving nanotech:

A
  1. nano powered catalytic device

2. nanofilters

57
Q

What is a nano-powered catalytic device, and what is the advantage? (3)

A

coated with 20nm zeolite NP (frying oil enhancing device)

better taste/consistency/crispness
lower cost
approved (FDA)

58
Q

what are nano-filters, and what are the advantages? (3)

A

filtration (extraction) method for food colors and flavors

gentle process (no phase change, heating, chemicals)
fresher flavors
cheaper (less energy needed)

59
Q

What is a nanomaterial?

A

film with incorporated nanoparticles (usually inorganic particles - silver, TiO2, nanoclay)

60
Q

Why are nanoparticles added to films? (2)

A

change functionalities:
antibacterial
improve barrier properties

61
Q

What are common NP added to films? (3)

A

silver, TiO2, nanoclay

62
Q

beer bottles can incorporate ____ NPs, which has the benefit of: (2)

A

nanoclay

lighter/stronger
minimize CO2 loss (better barrier)

63
Q

the possible distribution patterns when adding NP into a polymer:

A
  1. microcomposites: NP clump up
  2. nanocomposite: NP regularly arranged
  3. nanocomposite: NP disorderly arranged
64
Q

The greater the interatomic spacing (d-spacing), the (greater/less) the gas permeability

A

less

65
Q

an increased number of bilayers (applied layers of polymer + NP) on the substrate leads to (higher/lower) permeability

A

lower

66
Q

“Smart dust” - nanosensors have what potential applications?

A
  1. monitor humidity/temp (environment)
  2. detect food spoilage/freshness
  3. monitor soil conditions (precision farming)
67
Q

What is a ‘lab on a chip’

A

tiny device integrating many lab functions (sample collection/concentration/separation/detection)

NPs used as tags/labels -> better sensitivity

68
Q

What can a nano-electric tongue be used for?

A

QC for beverages

69
Q

What are self-evident shelf life labels and what can they indicate?

A

change color (signal) to indicate change in product

temp, pathogens, freshness, integrity, humidity, etc

70
Q

gas indicators examples: (2)

A

TiO2 NPs (with methylene blue indicator) - O2 sensor

C-coated Cu NPs: change colors according to gas or moisture (ethanol, H2O)

71
Q

Why is sensing CO2 increase relevant?

A

CO2 made by microbial respiration/fermentation

CO2 made by produce respiration

72
Q

What is a self-evident label that is a poultry freshness indicator, and how does it work?

A

Metmyoglobin based
detects H2S produced by bacteria (pseudomonas)
H2S react w/ metmyoglobin (brown) -> sulfmyoglobin (green)

green color = spoiled

73
Q

How does a ripeness indicator work?

A

detects CO2 (more ripe = more CO2) -> changes color from red to yellow

74
Q

What is an example of antibody-based freshness indicator? How does it work?

A

Toxin Guard

polyer with detector Ab (against specific pathogen toxins/spoilage metabolites)
Ab bind toxin -> complex binds to capture area on label
cause color change/fluorescence = product not safe

75
Q

what is the mechanism of a temperature dependent color changing plastic mug?

A

thermo-chromic dye incorporated into plastic - changes color according to temp
ex: coffee lid turning red when hot, back to brown when cool

76
Q

How does a 1 time usage temperature indicator work, and what is it used for?

A

bringing product to specific temp -> wax melts & mixes with dye
(irreversible)

color change indicates product has reached endpoint temperature

77
Q

What are some areas of safety concern for NP technology? (3)

A

Worker safety
Product safety
Environmental safety

78
Q

What are some concerns with product safety for NPs? (4)

A

dermal/inhalation/ingestion?
crossing biological membranes, cells, etc
bio-concentration
higher reactivity (larger surface area)

79
Q

examples of potential harm caused by exposure to NP:

A 
neuron degeneration
inflammation
organ injury
oxidative damage
necrosis
carcinogenic
80
Q

concerns with environmental safety of NPs:

A

multiple pathways to environment (manufacture, transport, use, disposal)

risks not fully assessed - mobility, reactivity, durability, bioaccumulation?

81
Q

nano silver has enhanced germ killing properties, but can also cause harm - how?

A

antimicrobial properties can also harm aquatic organisms/microbes and ecosystems

82
Q

What are the environmental and human health impacts of fullerenes (carbon 60)?

A

environment: brain damage in fish, kill water fleas, bacteriocidal
human: low levels toxic to hepatocytes

83
Q

How could TiO2 and ZnO be harmful to human health? What are they usually found in?

A

possibly photoactive - made free radicals and cause DNA damage in epithelial cells in UV light

in sunscreens

84
Q

For NP consumer safety, what needs to be ensured? (4)

A
  • ensure they are solubilized/digested in gut
  • ensure greater bioavailability doesnt increase health risks
  • tissue distribution not different from conventional forms
  • evaluate toxicological properties!
85
Q

What needs to be kept in mind in the future of NP development? (3)

A

weight risks vs benefits (risks acceptable?)
ensure regulatory compliance
consumer information

Food Packaging (11 decks)

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