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Flashcards in Nanomaterials Deck (85)
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1

T/F: all nanostructures are manmade

False; nanostructures occur naturally in many foods

2

Many food proteins are ____ structures between _____ nm in size

globular structures
10-100nm

3

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

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

4

Describe the nanostructure features of a stabilized foam:

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

5

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

starch nanocrystals (custard)
casein particles in milk

6

How do starch nanocrystals change in the process of custard making

heated starch -> nanocrystals melt
recrystallization/hydration during coolin -> forms paste

7

Casein particles are about ____ nm in milk.

100nm

8

How is milk converted to a gel in yogurt production?

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

9

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

New properties:

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

10

What is nanotechnology?

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

11

What is the scale (dimensions) for nanotechnology?

0.1-100nm

12

What technology is used to observe nanoparticles? (5)

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

13

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

dynamics light scattering
hydrodynamic diameter

14

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

faster

15

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

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

16

What is the principle of SEM?

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

17

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

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)

18

General mechanism of TEM:

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

19

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

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

20

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

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

21

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

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

22

What is nanotech used for in materials? (4)

nanoparticles
nanoemulsions
nanocomposites
nano-structured materials

23

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

nanoencapsulation (flavor/nutrient control, protect nutraceuticals)

engineered nanoparticulate addditives (nanosized ingredients)

24

how is nanotech involved in novel materials? (2)

antibacterial packaging
controlled gas permeability

25

How is nanotech involved in food safety?

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

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

26

What is nanoencapsulation?

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

27

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

Yes: usually liquid, but can be solid or gas

28

How is the emulsion method of nanoencapsulation done?

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

29

Benefits of encapsulation: (4)

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

30

The 3 emulsion methods for nanoencapsulation:

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)