Flashcards in Nanomaterials Deck (85)
T/F: all nanostructures are manmade
False; nanostructures occur naturally in many foods
Many food proteins are ____ structures between _____ nm in size
What are some naturally occuring nanostructure molecule types in food: (3)
stabilized foam/emulsions (interface)
Describe the nanostructure features of a stabilized foam:
2D nanostructure: 1 molecule thick at the interface (between the air/water or oil/water)
Give some examples of foods with nanoparticles (natural) (2)
starch nanocrystals (custard)
casein particles in milk
How do starch nanocrystals change in the process of custard making
heated starch -> nanocrystals melt
recrystallization/hydration during coolin -> forms paste
Casein particles are about ____ nm in milk.
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
What interesting phenomena can materials display at the nano-scale? (7)
new optical properties
molecular recognition (bind/disrupt) in endocrine/DNA
very attractive/repulsive surface charge
What is nanotechnology?
understanding/control of matter at the nanoscale (0.1-100nm) & the unique phenomena (property changes)
What is the scale (dimensions) for nanotechnology?
What technology is used to observe nanoparticles? (5)
SEM (scanning electron microscopy)
AFM (atomic force microscopy)
TEM (transmission electron microscopy)
The zetasizer measures nanoparticles based on _______, reporting it as _____
dynamics light scattering
Smaller particles will show (faster/slower) dynamics in a zetasizer
A Mastersizer works based on the principle of _____. How does it differentiate between particle sizes?
small particle -> more scattering
big particle -> less scatteriing
What is the principle of SEM?
electron beam directed at sample
electrons interact with sample -> produce signals
gives information on topography & composition
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)
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)
nanotechnology is applied in what food-related products? (7)
food procesing aids
What are possible future nano food and agriculture technology? (8)
interactive personalized food
edible nano wrapper
chem release packaging
extensive nano surveillance
nano-manipulation of seeds
nanotechnology is involved in what sectors of food science and technology?
What is nanotech used for in materials? (4)
How is nanotech used in health and nutrition? (2)
nanoencapsulation (flavor/nutrient control, protect nutraceuticals)
engineered nanoparticulate addditives (nanosized ingredients)
how is nanotech involved in novel materials? (2)
controlled gas permeability
How is nanotech involved in food safety?
small environmental sensors (humidity, frost, temp, light...)
self-evident shelf life labels (shows when food spoils/contaminated)
What is nanoencapsulation?
coating + entrapment of pure material or mixture inside another material (emulsion droplets < 100nm)
Can the core material in nanoencapsulation can be in forms other than liquid?
Yes: usually liquid, but can be solid or gas
How is the emulsion method of nanoencapsulation done?
disperse material in carrier solution -> coat with surfactant -> form emulsion droplets <100nm
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)