Lecture 10: Nanotechnology Flashcards
nanostructures occurs _____ in many foods
naturally
what is the size range of most food proteins?
10-100nm
most polysaccharides and lipids are what shape?
what thickness?
linear polymers
several nm in thickness
what are stabilized foams and emulsions?
2D nanostructures
how is custard produced?
heat starch to “melt” nanocrystals, then cool
this forms a paste due to the recrystallisation and hydration process
what is the size of casein particles in milk?
100nm
how is casein produced in milk?
lactic acid is released by microbial action which cleaves kappa chain
allows particles to grow to give a gel structure
what are properties of nano materials?
- high mobility
- new optical properties
- molecular recognition (binding/disruption) in DNA and hormone systems
- supermagnetism
- superconductivity
- increased reactivity
- attractive/repulsive surface charge
what is nanotechnology?
- controlling matter at 0.1-100nm
- includes H atom, DNA, ATPsnthases, viruses, etc…
what is the size of human hair?
100,000nm
what is the zetasizer?
used to observe nanothings
gives you graph of intesntiy vs radius of molecule
what is the mastersizer?
- applies shear stress which causes velocity gradients
- creates particle-wall collisions and particle-particle collisions
what is SEM?
scanning electron microscopy
- electron beam comes from electron gun
- electron passes through two condensor lenses, deflection coils and backscatter detector
- enters secondary electron detector and then x-ray detector
what is AFM?
atomic force microscopy
- laser shoots photodiode to detector
- single polymer chains are recorder under aqueous media w/ different pH
what is TEM?
transmission electron microscopy
- E beam goes through sample to graphite block.
- gold reflectors reflect e-beam to SED
what are applications of nanotechnology?
material science engineering surface treatment life science diagnostics
what are food products that use nanotechnology?
diet supplements nutritional additives color additives food processing aids long-life packaging anti-bacterial kitchenware fertiliser
what are applications of nanotech in the health and nutrition?
nanoencapsulation (flavour and nutrient control)
engineered nanoparticulate additives
what are applications of nanotech in novel materials?
antibacterial packaging
controlled gas permeability
what are applications of nanotech in food safety?
small environmental sensorys (humidity, frost, temp, etc…)
self evident shelf life labels
what is nanoencapsulation
coating and entrapment of a pure material or mixture into another material
the coated or entrapped material is usually a liquid, but can also be a solid or gas
examples of materials used: birds egg shells, plant seeds, bacterial spores, skin, seashells
what is the size of an emulsion droplet?
<100nm
what are the two components in nanoemulsion?
emulsion droplet and surfactant
what are reasons for encapsulation of flavours?
- stability: stable against heat, pH, oxidation in food processing
- taste and color: no unpleasant taste or color
- safety: mild on stomach b/c of its insolubility in gastric juices
- bioavailability: sustained release, high absorption and bioavailability
what are 3 methods of nanoencapsulation of flavors? what does each consist of?
- extreme emulsification (extreme flow)
- phase inversion composition
- phase inversion temp (low flow and quenching temp)
what equipment is used to make nanoencapsulation of flavours? describe the steps of this
spray drying
- drying gas flow enters through heater to the drying chamber
- goes through a collecting electrode to a grounded electrode
what is the state of flavours before and after spray drying?
before: flavor emulsion is in liquid state
after: encapsulated flavor powder is in a solid state
what is NSSL?
nano sized self assembled liquid structures
emulsions of 30nm
used for nanoencapsulation
what molecules are used in nanoencapsulation?
coenzyme Q10 (ubiquinone) lutein lycopene phytosterol (sitosteroil) vit D
describe coenzyme Q10 in nanoencapsulation
- not soluble in water
- bioavailability of CoQ10 can be reduced with a diet high in fiber
- fortifying a nano-vehicle with CoQ10 enables its fortification into water or oil based food products
describe phytosteroils in nanoencapsulation
- more effective in competition w/ cholesterol
- high effectiveness of solubility and transfer of phytosterol to the bile salt micelles in place of cholesterol
- improves solubility
- allows transportation without breaking up
- can identify large micelle membrane and compete for transportation
what are components of omega 3 bread that uses nanoencapsulation?
why is nanoencapsulation needed for this?
tuna fish oil
this allows mixing omega 3 into foods that can’t normally hide the fish flavor in which the oils more readily break down
what are types of chemical cross-linked nanoparticles
common cross linker:
- glutaraldehyde (toxic)
novel crosslinkers:
- genipin
- natural di and tri carboxylic acids
what is the difference between chemical and physical cross linked nanoparticles?
chemical: has chemical bonds between particles
physical: has electrostatic interactions within the particle
what are types of physical cross linked nanoparticles?
- anion crosslinker: tripolyphoshate (TPP)
2. cation crosslinker: bivalent Ca2+
alginate nanoparticles crosslinked by Ca2+ is an example of what?
a physical-cross linked nanoparticle
what are 2 methods of loading bioactive compounds?
during preparation (incorporation)
after preparation (incubation)
wood cellulose based polyelectrolyte nanoparticles are made from what?
carboxymethyl cellulose and quaternized cellulose
what are advantages of physical cross linked nanoparticles?
- no chemical crosslinking reagents
- mild aqueous conditions
- simple procedures
- suitable for bioactive agents
what are examples of nano-sized ingredients and additives?
- colors, flavouring agents, preservative, antioxidants
- lycopene
- nano-salt
- mineral supplements (Ca, Mg, Fe, Zn, etc…)
- nano-tea (“slim-shake chocolate”)
what are the benefits of using nanosized ingredients and additives?
- better texture, flavor, taste
- reduction in amont of salt, fat, sugar
- enhanced bioavailability and health benefits
how is nanotechnology used in a nutritional supplement drink for toddlers?
uses nano iron
increases bioavailability of the iron
how is nanotechnology used in nano chicken feed?
nano selenium may stop bird flu b/c polystyrene nanoparticles bind w/ bacteria as alternative to chemical antibiotics
describe the nano powdered catalytic device
- coated with 20nm width zeolite nanoparticles
- better taste and crisper deep fried foods
- better consistency of pdt
- lower costs
describe the use of nano filters for food coloring and flavoring
- gentle process
- doesn’t involve phase change, heating or chemical extraction
- produces fresher flavors
- cheaper because it uses less energy
what particles are usually incorporated into films?
what is the result of this?
inorganic particles (silver, TiO2, nanoclay)
changes functionalities of packaging materials (antibacterial packaging, improves barriers to O2 and moisture)
what are effects of adding nanoparticles in packaging?
- damages cell membranes to reduce E.coli growth and viability
- affects particle size, surface charge, etc…
what are characteristics of nanoclay particle based beer bottles?
- lighter and stronger
- minimizes loss of CO2 from beer
describe the organization of clay platelets and polymers in
a) microcomposites
b) nanocomposites
microcomposites:
- clay platelets are clustered with polymer around it
nano:
- polymer is between each clay platelets
what are applications of smart dust?
- monitors humidity, temp, environment
- detects onset of food spoilage and food freshness
- monitor soil conditions and crop growth for precision farming
what are types of nanosensors?
- CO2
- acoustic
- odour
- pressure
- temp
- humidity and dust
what is the use of nanoelectric tongue?
for quality control fo beverages by electronic tongue
what are gas indicators for shelf-life labels?
O2
ethanol
water vapour
describe the use of CO2 as a gas indicator in self evident shelf life labels
critical conc of CO2 causes colour change due to
- microbial respiration and fermentation
- produce respiration
describe the use of hydrogen sulfide as a gas indicator in self evident shelf life labels
- used as a poultry freshness indicator
- metmyoglobin based, which is normally brown
- when metmyoglobin reacts with H2S produced by bacteria, it produces sulfmyoglobin (green)
- brown to green color change: indicates loss of freshness due to bacterial growth
what does green color due to hydrogen sulfide with poultry indicate?
indicates loss of freshness due to bacterial growth
what is ripesense?
how does it work?
a ripeness indicator (self-evident shelf-life label)
as ripeness increases, volatiles cause a change in indicator from red to yellow
what is toxin guard? how does it work?
type of self-evident shelf life label used to detect specific molecules (eg. toxins) produced by spoilage bacteria
- when toxins are produced by pathogens, detector antibodies are incorporated into a polymer
- detector Ab binds to toxin
- detector antibody-toxin complex binds to capture area on label
- binding to label causes color change or fluorescence which indicates product is not safe
describe the temperature indicator
- type of self-evident shelf life label
- thermo-chromic dye is incorporated in the plastic
- coffee brown colour changes to red when heated
- red colour indicates that (1) contents are hot (2) lid has been properly attached (3) coffee has not become too cold to drink
- overall, when red, the end-point temp has been reached. This occurs b/c at the end-point temp, a wax melts and irreversibly mixes with red dye
what are some product safety concerns of nanotechnology?
- dermal, inhalation and ingestion
- crossing biological membranes, cells, tissue, organs
- organ bio-concentration
- increased SA which provides increased reactivity
what are some environment safety concerns of nanotechnology?
risks involving mobility, transportation, reactivity, durability and bioaccumulation during manufacture, transport, use, disposal that is not fully assessed yet
describe the use of nano silver in food and its effects on the environment
- inserted for nano-enhanced germ-killing properties
- has antimicrobial properties
- but the same properties can also seriously harm aquatic organism, microorganism, ecosystems
describe the use of carbon fulereness in food and its effects on the environment and human health
- used in face and anti-aging creams
- environmental impacts: brain damage in fish, kills water fleas, has bactericidal properties
- human health impacts: low levels can be toxic to human liver cells
describe the use of nano-sunscreen and effects on human health
- nanoparticles of titanium dioxide and zinc oxide which are photoactive
- but produces free radicals and causes DNA damage to human skin cells when exposed to UV light
what are general consumer safety concerns of nanotechnology?
- need to ensure nanostructures are solubilized/digested in the gut
- need to ensure that greater bioavailability does not lead to increased health risks
- toxicological properties of most nanoparticles are not yet known
how can we move forward with use of nanoparticles?
industry should only use nano products when benefits > risks. The risks must be acceptable
assure product quality and promote research to ensure compliance, give case-by-case assessment of potential risks, give consumer information in regard to benefits and risks
