Applications of nanotechnology for the food sector - Sideversjonshistorikk

Schlanbu på 8. apr. 2009 kl. 13:12

2009-04-08T13:12:15Z

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	~~STILL UNDER CONSTRUCTION --fredrik and reidun~~

	==Introduction==		==Introduction==
	[[Image:lab.jpg\|right\|thumb\|400px\|]]		[[Image:lab.jpg\|right\|thumb\|400px\|]]

Schlanbu: /* Health risks */

2009-04-08T13:10:36Z

Health risks

← Eldre sideversjon		Sideversjonen fra 8. apr. 2009 kl. 13:10
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	== Health risks ==		== Health risks ==
	It is known that materials at nano-scale exhibit different properties than found at macro-scale. An extreme example concerning different properties at different scales is aluminum oxide. Aluminum oxide is used in dentistry because it is inert at macro-scale, but when manufactured as nano-scale particles it can spontaneously explode and has been tested as a potential rocket fuel. Examining new nano-materials properties as particle size, mass, chemical composition, aggregation, and surface charge of the nanoparticles must be done. There are currently available data that indicates that properties of nanoparticles, such as surface charge and functional groups can influence absorption, metabolism, distribution and excretion. Still, very little is known how these physio-chemical properties will affect the behavior of the particles in the body. It is three possible ways a nanoparticle, or any particle, could enter the human body. That is through the skin, through inhalation or through ingestion.<ref name="chi-fai_chau"/><ref name="health"/>		It is known that materials at nano-scale exhibit different properties than found at macro-scale. An extreme example concerning different properties at different scales is aluminum oxide. Aluminum oxide is used in dentistry because it is inert at macro-scale, but when manufactured as nano-scale particles it can spontaneously explode and has been tested as a potential rocket fuel. Examining new nano-materials properties as particle size, mass, chemical composition, aggregation, and surface charge of the nanoparticles must be done. There are currently available data that indicates that properties of nanoparticles, such as surface charge and functional groups can influence absorption, metabolism, distribution and excretion. Still, very little is known how these physio-chemical properties will affect the behavior of the particles in the body.

			===Entrance of nanoparticles in the human body===
			It is three possible ways a nanoparticle, or any particle, could enter the human body. That is through the skin, through inhalation or through ingestion.<ref name="chi-fai_chau"/><ref name="health"/>

	~~===Entrance of nanoparticles===~~
	====Dermal exposure====		====Dermal exposure====
	Nanoparticles can have an impact if they penetrate the outer layers of the skin. Some studies show that a healthy epidermis (the outermost layer of the skin) could protect against nanoparticles. There are findings that fluorecent microspheres or dextran beads (>1<math>\mu</math>m) can, when in motion, penetrate the stratum corneum (the uppermost sublayer of the epidermis), go down in the epidermis and occasionally reach the dermis. If nanoparticles penetrate the dermis they could translocate via lymph to regional lymph nodes. Some researches claim that small titanium dioxide particles (about 20nm in diameter) could even interact with the immune system when they penetrate the skin. It should of course be noticed that possible health consequences still remain rather speculative.<ref name="chi-fai_chau"> Chau C, Wu S, Yen G, "The development of regulations for food nanotechnology", Trends in Food Science & Technology (2007) 18: 269-270 </ref>		Nanoparticles can have an impact if they penetrate the outer layers of the skin. Some studies show that a healthy epidermis (the outermost layer of the skin) could protect against nanoparticles. There are findings that fluorecent microspheres or dextran beads (>1<math>\mu</math>m) can, when in motion, penetrate the stratum corneum (the uppermost sublayer of the epidermis), go down in the epidermis and occasionally reach the dermis. If nanoparticles penetrate the dermis they could translocate via lymph to regional lymph nodes. Some researches claim that small titanium dioxide particles (about 20nm in diameter) could even interact with the immune system when they penetrate the skin. It should of course be noticed that possible health consequences still remain rather speculative.<ref name="chi-fai_chau"> Chau C, Wu S, Yen G, "The development of regulations for food nanotechnology", Trends in Food Science & Technology (2007) 18: 269-270 </ref>

	====Inhalation====		====Inhalation====
	If a particle has a aerodynamic diameter less than 10<math>\mu</math>m it can pass through the nasal cavity to the lungs. The aerodynamic diameter describes the particles aerodynamical behaviour as if it was a perfect sphere with density 1.<ref name="aero">Website: http://en.wikipedia.org/wiki/Aerodynamic_diameter, visited 2009.03.17</ref> ~~Studies indicate that nanoparticles, because of their size, are more toxic than larger particles of the same material.~~ The particles can get deep into the lungs, and when inhaled, some nanoparticles may accumulate in the lungs and cause cronic diseases such as pulmonary (lung) inflammation. There are also speculations if the particles when in the blood stream, would be able to cross the blood brain barrier. However, it is ~~also here~~ hard to draw conclusions and individual nanomaterials needs to be evaluated.<ref name="chi-fai_chau"/>		If a particle has a aerodynamic diameter less than 10<math>\mu</math>m it can pass through the nasal cavity to the lungs. The aerodynamic diameter describes the particles aerodynamical behaviour as if it was a perfect sphere with density 1.<ref name="aero">Website: http://en.wikipedia.org/wiki/Aerodynamic_diameter, visited 2009.03.17</ref> The particles can get deep into the lungs, and when inhaled, some nanoparticles may accumulate in the lungs and cause cronic diseases such as pulmonary (lung) inflammation. There are also speculations if the particles when in the blood stream, would be able to cross the blood brain barrier. However, it is again hard to draw conclusions and individual nanomaterials needs to be evaluated.<ref name="chi-fai_chau"/>

	====Ingestion====		====Ingestion====
	Nanoparticles can avoid intestinal clearance mechanisms and penetrate deeply into tissues and fine capillaries. It seems that small particles can penetrate the mucus layer faster than larger particles. In the mucus layer, it also seems that the diffusion is dependent of the charge of the particles. Some experiments show that anions can reach the epithelial surface under the mucus layer, while cations stays trapped in the mucus. The gastrointestinal epithelium is the second barrier the particles reach ~~and it consists of a tissue of cells that line cavities and surfaces of structures~~.<ref name="epithelium">Website: http://en.wikipedia.org/wiki/Epithelium visited 2009.03.23</ref> The cells in the gastrointestinal epithelium are connected with tight junctions and as bacterias, toxins and immunogens can enter here it is to be considered a risk that nanoparticles can enter through this way. In addition to those particles directly ingested, particles inhaled and cleared by the mucociliary apparatus can end up in the gastrointestional tract.<ref name="chi-fai_chau"/><ref name="health"/>		Nanoparticles can avoid intestinal clearance mechanisms and penetrate deeply into tissues and fine capillaries. It seems that small particles can penetrate the mucus layer faster than larger particles. In the mucus layer, it also seems that the diffusion is dependent of the charge of the particles. Some experiments show that anions can reach the epithelial surface under the mucus layer, while cations stays trapped in the mucus. The gastrointestinal epithelium is the second barrier the particles reach.<ref name="epithelium">Website: http://en.wikipedia.org/wiki/Epithelium visited 2009.03.23</ref> The cells in the gastrointestinal epithelium are connected with tight junctions and as bacterias, toxins and immunogens can enter here it is to be considered a risk that nanoparticles can enter through this way. In addition to those particles directly ingested, particles inhaled and cleared by the mucociliary apparatus can end up in the gastrointestional tract.<ref name="chi-fai_chau"/><ref name="health"/>

	===Distribution of entered nanoparticles===		===Distribution of entered nanoparticles===
	Even though little is known about the nutrional effect of having functional ingredients as nanoparticles there have been done some research on the distribution of nanoparticles in the human body.		Even though little is known about the nutrional effect of having functional ingredients as nanoparticles there have been done some research on the distribution of nanoparticles in the human body.

	There are tests indicating that nanoparticles will have a widespread distribution inside an animal body, where the smallest particles even can reach the brain and bone marrow. Also in a cellular level there are indications that cell membranes can be penetrated by nanoparticles. Gold and titanium-oxide nanoparticles have been identified inside human red blood cells. The blood-brain barrier restricts permeability to the molecules which are lipophilic~~, actively transported or small soluble~~, but there exist eveidence that some nanoparticles can cross this barrier.<ref name="health"/>		There are tests indicating that nanoparticles will have a widespread distribution inside an animal body, where the smallest particles even can reach the brain and bone marrow. Also on a cellular level there are indications that cell membranes can be penetrated by nanoparticles. Gold and titanium-oxide nanoparticles have been identified inside human red blood cells. The blood-brain barrier restricts permeability to the molecules which are lipophilic, but there exist eveidence that some nanoparticles can cross this barrier.<ref name="health"/>

	==References==		==References==

	<references/>		<references/>

Schlanbu: /* Nanolaminates */

2009-04-08T13:00:11Z

Nanolaminates

← Eldre sideversjon		Sideversjonen fra 8. apr. 2009 kl. 13:00
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	* Changing the order of the dipping steps.		* Changing the order of the dipping steps.

	There are still many uncertainties for this technique. For instance the influence of the topography of the surface on ~~the effect of~~ the coating has still not been properly established.<ref name="weiss"/>		There are still many uncertainties for this technique. For instance, the influence of the topography of the surface on the coating has still not been properly established.<ref name="weiss"/>

	====Biopolymer nanofibres====		====Biopolymer nanofibres====

Schlanbu: /* Nano outside - functional food packaging */

2009-04-08T12:57:47Z

Nano outside - functional food packaging

← Eldre sideversjon		Sideversjonen fra 8. apr. 2009 kl. 12:57
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	Nanocomposites have also been developed using for example chitosan. Chemically derived by deacetylation of chitin, an abundant polysaccharide found in shellfish, chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It has a number of commercial and possible biomedical applications<ref name="chitosan"> Website: Chitosan (http://en.wikipedia.org/wiki/Chitosan)Visited 22.03.2009 </ref>. Chitosan possesses a unique cationic nature relative to other neutral or negatively charged polysaccharides. In an acid environment, the amino group NH2 in chitosan can be protonated to NH3 +, which yields antifungal or antimicrobial activities since cations can bind to anionic sites on bacterial and fungal cell wall surfaces. Further, chitosan is a nontoxic natural polysaccharide and is compatible with living tissue.		Nanocomposites have also been developed using for example chitosan. Chemically derived by deacetylation of chitin, an abundant polysaccharide found in shellfish, chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It has a number of commercial and possible biomedical applications<ref name="chitosan"> Website: Chitosan (http://en.wikipedia.org/wiki/Chitosan)Visited 22.03.2009 </ref>. Chitosan possesses a unique cationic nature relative to other neutral or negatively charged polysaccharides. In an acid environment, the amino group NH2 in chitosan can be protonated to NH3 +, which yields antifungal or antimicrobial activities since cations can bind to anionic sites on bacterial and fungal cell wall surfaces. Further, chitosan is a nontoxic natural polysaccharide and is compatible with living tissue.
	These appealing features make chitosan widely applicable in wound healing, production of artificial skin, food preservation, and cosmetics.		These appealing features make chitosan widely applicable in wound healing, production of artificial skin, food preservation, and cosmetics.



	====Biodegredable polymers====		====Biodegredable polymers====

Schlanbu: /* Chitosan */

2009-04-08T12:56:59Z

Chitosan

← Eldre sideversjon		Sideversjonen fra 8. apr. 2009 kl. 12:56
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	====Chitosan====		====Chitosan====
	[[Image:Chitosan_Haworth.jpg\|left\|thumb\|200px\|'''Chitosan:''' Haworth projection of chitosan<ref name="chitosan"> Website: Chitosan (http://en.wikipedia.org/wiki/Chitosan)Visited 22.03.2009 </ref>.]]		[[Image:Chitosan_Haworth.jpg\|left\|thumb\|200px\|'''Chitosan:''' Haworth projection of chitosan<ref name="chitosan"> Website: Chitosan (http://en.wikipedia.org/wiki/Chitosan)Visited 22.03.2009 </ref>.]]
	Nanocomposites have also been developed using for example chitosan. Chemically derived by deacetylation of chitin, an abundant polysaccharide found in shellfish, chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It has a number of commercial and possible biomedical ~~uses~~<ref name="chitosan"> Website: Chitosan (http://en.wikipedia.org/wiki/Chitosan)Visited 22.03.2009 </ref>. Chitosan possesses a unique cationic nature relative to other neutral or negatively charged polysaccharides. In an acid environment, the amino group NH2 in chitosan can be protonated to NH3 +, which yields antifungal or antimicrobial activities since cations can bind to anionic sites on bacterial and fungal cell wall surfaces. Further, chitosan is a nontoxic natural polysaccharide and is compatible with living tissue.		Nanocomposites have also been developed using for example chitosan. Chemically derived by deacetylation of chitin, an abundant polysaccharide found in shellfish, chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It has a number of commercial and possible biomedical applications<ref name="chitosan"> Website: Chitosan (http://en.wikipedia.org/wiki/Chitosan)Visited 22.03.2009 </ref>. Chitosan possesses a unique cationic nature relative to other neutral or negatively charged polysaccharides. In an acid environment, the amino group NH2 in chitosan can be protonated to NH3 +, which yields antifungal or antimicrobial activities since cations can bind to anionic sites on bacterial and fungal cell wall surfaces. Further, chitosan is a nontoxic natural polysaccharide and is compatible with living tissue.
	These appealing features make chitosan widely applicable in wound healing, production of artificial skin, food preservation, and cosmetics.		These appealing features make chitosan widely applicable in wound healing, production of artificial skin, food preservation, and cosmetics.

Schlanbu: /* Composites with metalparticles */

2009-04-08T12:54:25Z

Composites with metalparticles

← Eldre sideversjon		Sideversjonen fra 8. apr. 2009 kl. 12:54
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	====Composites with metalparticles====		====Composites with metalparticles====
	Polymer nanocomposites incorporating metal or metal oxide nanoparticles have been developed for packaging because of their antimicrobial or for example UV-resistant properties. Based on the antimicrobial action of nanosilver, a number of "active" food packaging materials has been claimed to inhibiting the growth of microorganisms. Examples from the internet include "Nano Silver Food Containers" form A-DO Korea, and "Nano Silver Baby Dream Co. Ltd. from South Korea. Silver has been used in medical care for ages because of its antimicrobial properties. Silvernanoparticles are currently being used in a wide range of consumer products including antibacterial refrigerators and socks. When in contact with bacteria and fungus the silver nano particles will adversely affect cellular metabolism and inhibit cell growth. The silver suppresses respiration and transport of substrate in the microbial cell membrane due to the chemical properties of its ionized form, Ag+. Ag+ forms strong molecular bonds with substances used by bacteria, such as molecules containing sulfur, nitrogen, and oxygen. Once the Ag+ ion complexes with these molecules, they are rendered unusable by the bacteria, depriving it of necessary compounds and eventually leading to the bacteria's death.		Polymer nanocomposites incorporating metal or metal oxide nanoparticles have been developed for packaging because of their antimicrobial or for example UV-resistant properties. Based on the antimicrobial action of nanosilver, a number of "active" food packaging materials has been claimed to be inhibiting the growth of microorganisms. Examples from the internet include "Nano Silver Food Containers" form A-DO Korea, and "Nano Silver Baby Dream Co. Ltd. from South Korea. Silver has been used in medical care for ages because of its antimicrobial properties. Silvernanoparticles are currently being used in a wide range of consumer products including antibacterial refrigerators and socks. When in contact with bacteria and fungus the silver nano particles will adversely affect cellular metabolism and inhibit cell growth. The silver suppresses respiration and transport of substrate in the microbial cell membrane due to the chemical properties of its ionized form, Ag+. Ag+ forms strong molecular bonds with substances used by bacteria, such as molecules containing sulfur, nitrogen, and oxygen. Once the Ag+ ion complexes with these molecules, they are rendered unusable by the bacteria, depriving it of necessary compounds and eventually leading to the bacteria's death.

	====Chitosan====		====Chitosan====

Schlanbu: /* Composites with nanoclay */

2009-04-08T12:53:00Z

Composites with nanoclay

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	====Composites with nanoclay====		====Composites with nanoclay====
	The polymer composites incorporating clay nanoparticles are among the first nanocomposites to emerge on the market as improved materials for food packaging. The nanoclay mineral used in these materials, montimorillonite, is a widely available natural clay derived from volcanic ash and rocks<ref name="chaudry">Chaudry, Scotter, Blackburn, Ross, Boxall, Castle, Aitken & Watkins, "Applications and implicatons of nanotechnologies for the food sector", Food Additives and Contaminants, March 2008</ref>. The clay has a unique morphology that contains one dimension on the nanoscale. Nanoclay-composites have been developed for potential use in a variety of food packaging applications and some products are already available for the consumer. The montmorillonite is hydrated alumina-silicatelayered clay. This special clay has a structure that limits the permeation of gas due to the large aspect ratio and tutourity <ref name="applications"> Sozer & Kokini, Nanotechnology and its applications in the food sector, Trends in Biotechnology Vol.27 No.2 </ref>. To obtain the polymer composite improvements mentioned above, a small percentage of clay can be included in the polymer matrix. This process is called solid layer dispersion in ~~polymer~~ and involves two major steps; intercalation and exfoliation<ref name="sorrentino"> Sorrentino, Gorrasi & Vittora, "Potential perpectives of bio-nanocomposites for food packaging applications, Trends in Foof Science and Technology 18, 2007 </ref>. In the intercalation step, the d-spacing in the crystal structure increases from its intrinsic value, as polymer chains or monomer molecules diffuse into the clay gallaries. In an intercalated state, the inorganic layers remain parallel to each other. In exfoliation, the clay particles are released from this system and are dispersed in the matrix polymer with no apparent particle interactions. The result is layers of nanoclay woven into the polymers structural matrix. Introduction of the dispersed clay layers into the polymer matrix structure has been shown to greatly improve the overall mechanical strength and barrier properties of the material, making the use of nanocomposites films industrially practicable<ref name="sorrentino"> "sorrentino." Sorrentino, Gorrasi & Vittora, "Potential perpectives of bio-nanocomposites for food packaging applications, Trends in Food Science and Technology 18, 2007 </ref>. The known industrial applications of nanoclay in multilayer film packaging include beer bottles and thermoformed containers. Miller Brewing Co. (USA) and Hite Brewery Co. (South Korea) have reported to be using this technology in their beer bottles.		The polymer composites incorporating clay nanoparticles are among the first nanocomposites to emerge on the market as improved materials for food packaging. The nanoclay mineral used in these materials, montimorillonite, is a widely available natural clay derived from volcanic ash and rocks<ref name="chaudry">Chaudry, Scotter, Blackburn, Ross, Boxall, Castle, Aitken & Watkins, "Applications and implicatons of nanotechnologies for the food sector", Food Additives and Contaminants, March 2008</ref>. The clay has a unique morphology that contains one dimension on the nanoscale. Nanoclay-composites have been developed for potential use in a variety of food packaging applications and some products are already available for the consumer. The montmorillonite is hydrated alumina-silicatelayered clay. This special clay has a structure that limits the permeation of gas due to the large aspect ratio and tutourity <ref name="applications"> Sozer & Kokini, Nanotechnology and its applications in the food sector, Trends in Biotechnology Vol.27 No.2 </ref>. To obtain the polymer composite improvements mentioned above, a small percentage of clay can be included in the polymer matrix. This process is called solid layer dispersion in polymers and involves two major steps; intercalation and exfoliation<ref name="sorrentino"> Sorrentino, Gorrasi & Vittora, "Potential perpectives of bio-nanocomposites for food packaging applications, Trends in Foof Science and Technology 18, 2007 </ref>. In the intercalation step, the d-spacing in the crystal structure increases from its intrinsic value, as polymer chains or monomer molecules diffuse into the clay gallaries. In an intercalated state, the inorganic layers remain parallel to each other. In exfoliation, the clay particles are released from this system and are dispersed in the matrix polymer with no apparent particle interactions. The result is layers of nanoclay woven into the polymers structural matrix. Introduction of the dispersed clay layers into the polymer matrix structure has been shown to greatly improve the overall mechanical strength and barrier properties of the material, making the use of nanocomposites films industrially practicable<ref name="sorrentino"> "sorrentino." Sorrentino, Gorrasi & Vittora, "Potential perpectives of bio-nanocomposites for food packaging applications, Trends in Food Science and Technology 18, 2007 </ref>. The known industrial applications of nanoclay in multilayer film packaging include beer bottles and thermoformed containers. Miller Brewing Co. (USA) and Hite Brewery Co. (South Korea) have reported to be using this technology in their beer bottles.

Schlanbu: /* Biopolymeric nanoparticles */

2009-04-08T12:48:59Z

Biopolymeric nanoparticles

← Eldre sideversjon		Sideversjonen fra 8. apr. 2009 kl. 12:48
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	====Biopolymeric nanoparticles====		====Biopolymeric nanoparticles====

	Biopolymeric nanoparticles are made of one or several biodegradable polymers. PLA (polylactic acid) is a main component of many biopolymeric nanoparticles. PLA is already widely used in for instance biomedicine because it is biodegradable and can be used for surgery (for instance as sutures). The biodegradable property of PLA can be both an advantage and disadvantage. It will degrade quickly in the bloodstream and therefore it can be suitable for delivering functional ingredients there, but if the ingredient is supposed to be carried to another internal organ the encapsulation will most likely degrade. PLA also degrades in intestinal fluid, but this can be overcome by adding a a hydrophilic compound. PEG (polyethylene glycol) is often used ~~here~~. A PLA-PEG diblock compound can be able to form a micellar structure and entrap the compound that is to be delivered. PLA and PLA-PEG nanoparticles have very good encapsulation properties, but the main reason for using these particles for a delivery system is that they are non-toxic. PLA-PEG-particles will have a lower zeta potential (a lower surface charge) than PLA-particles, and this will influence the interaction of the particles with other compounds in the food.<ref name="weiss"/>		Biopolymeric nanoparticles are made of one or several biodegradable polymers. PLA (polylactic acid) is a main component of many biopolymeric nanoparticles. PLA is already widely used in for instance biomedicine because it is biodegradable and can be used for surgery (for instance as sutures). The biodegradable property of PLA can be both an advantage and disadvantage. It will degrade quickly in the bloodstream and therefore it can be suitable for delivering functional ingredients there, but if the ingredient is supposed to be carried to another internal organ the encapsulation will most likely degrade before reaching its destination. PLA also degrades in intestinal fluid, but this can be overcome by adding a a hydrophilic compound. PEG (polyethylene glycol) is often used for this task. A PLA-PEG diblock compound can be able to form a micellar structure and entrap the compound that is to be delivered. PLA and PLA-PEG nanoparticles have very good encapsulation properties, but the main reason for using these particles for a delivery system is that they are non-toxic. PLA-PEG-particles will have a lower zeta potential (a lower surface charge) than PLA-particles, and this will influence the interaction of the particles with other compounds in the food.<ref name="weiss"/>

	==Nano outside - functional food packaging==		==Nano outside - functional food packaging==

Schlanbu: /* Emulsions */

2009-04-08T12:45:41Z

Emulsions

← Eldre sideversjon		Sideversjonen fra 8. apr. 2009 kl. 12:45
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	====Emulsions====		====Emulsions====
	[[Bilde:Emulsion.gif\|right\|thumb\|200px\|An oil-in-water (O/W) emulsion<ref name="emulsion>Website: http://www.ifr.ac.uk/Materials/fractures/emulsions.html Visited: 2009.03.22</ref>]]The delivery of nano particles applied in food technology is very often in form of emulsions (nanoemulsions)<ref name="health">Bouwmeester H, Dekkers S, Noordam MY, Hagens WI, Bulder A, Heer C, ten Voorde SECG, Wijnhoven S, Marvin HJP, Sips AJAM, "Review of health safety aspects of nanotechnologies in food production", (2009), Regulatory Toxicology and Pharmacology 53 (2009); 52–62</ref>An emulsion is a mixture of two or more liquids where one is distributed as droplets in the other ~~liquid~~. <ref name="emulsion">Website: Encyclopædia Britannica. 2009. Encyclopædia Britannica Online. 14. Mar. 2009 (http://www.britannica.com/EBchecked/topic/186307/emulsion)</ref> One should notice that nano-emulsions have similar properties to emulsions (unlike microemulsions which have different thermodynamic properties than emulsions). Nano-emulsions have a droplet size of 20nm to 500nm. The formation is not spontaneous and their properties do not only depend on thermodynamic conditions, but also the way they are prepared.<ref name="porrasa">M. Porrasa, C. Solansb, C. Gonzáleza, A. Martíneza, A. Guinarta and J.M. Gutiérre, "Studies of formation of W/O nano-emulsions", Colloids and Surfaces A: Physicochemical and Engineering Aspects (2004); 115-118</ref> [[Bilde:multilayeremulsion.jpg\|right\|thumb\|350px\|Illustration of fabrication of multilayer emulsion<ref name="weiss"/>]]Encapsulating functional components in the droplets and modication of the interfacial layer between the droplet and the continuous have been shown to have a slowdown of the chemical degradation process.<ref name="weiss"/> Multiple emulsions, emulsions containing several layers can also be used (for instance a oil-in-water-in-oil emulsion (O/W/O). The advantage using the multiple emulsions is that phase components that are soluble in the same type of phase can be separated and still contained in the same colloidal particle. Multilayer emulsions, emulsion containg only one phase but has a multilayer interface has also been researched. Emulsions with oil droplets surrounded by multilayer interfaces have been shown to have better stability against enviromental stress than single layer emulsions. The multiple layers can be made by electrostatic deposition in which polyelectrolytes are adsorbed on surfaces of oppositely charged colloidal particles. <ref name="weiss"/><ref name="porrasa">M. Porrasa, C. Solansb, C. Gonzáleza, A. Martíneza, A. Guinarta and J.M. Gutiérre, "Studies of formation of W/O nano-emulsions", Colloids and Surfaces A: Physicochemical and Engineering Aspects (2004); 115-118</ref>		[[Bilde:Emulsion.gif\|right\|thumb\|200px\|An oil-in-water (O/W) emulsion<ref name="emulsion>Website: http://www.ifr.ac.uk/Materials/fractures/emulsions.html Visited: 2009.03.22</ref>]]The delivery of nano particles applied in food technology is very often in form of emulsions (nanoemulsions)<ref name="health">Bouwmeester H, Dekkers S, Noordam MY, Hagens WI, Bulder A, Heer C, ten Voorde SECG, Wijnhoven S, Marvin HJP, Sips AJAM, "Review of health safety aspects of nanotechnologies in food production", (2009), Regulatory Toxicology and Pharmacology 53 (2009); 52–62</ref>An emulsion is a mixture of two or more liquids where one is distributed as droplets in the other. <ref name="emulsion">Website: Encyclopædia Britannica. 2009. Encyclopædia Britannica Online. 14. Mar. 2009 (http://www.britannica.com/EBchecked/topic/186307/emulsion)</ref> One should notice that nano-emulsions have similar properties to emulsions (unlike microemulsions which have different thermodynamic properties than emulsions). Nano-emulsions have a droplet size of 20nm to 500nm. The formation is not spontaneous and their properties do not only depend on thermodynamic conditions, but also the way they are prepared.<ref name="porrasa">M. Porrasa, C. Solansb, C. Gonzáleza, A. Martíneza, A. Guinarta and J.M. Gutiérre, "Studies of formation of W/O nano-emulsions", Colloids and Surfaces A: Physicochemical and Engineering Aspects (2004); 115-118</ref> [[Bilde:multilayeremulsion.jpg\|right\|thumb\|350px\|Illustration of fabrication of multilayer emulsion<ref name="weiss"/>]]Encapsulating functional components in the droplets and modication of the interfacial layer between the droplet and the continuous have been shown to have a slowdown of the chemical degradation process.<ref name="weiss"/> Multiple emulsions, emulsions containing several layers can also be used (for instance a oil-in-water-in-oil emulsion (O/W/O). The advantage using the multiple emulsions is that phase components that are soluble in the same type of phase can be separated and still contained in the same colloidal particle. Multilayer emulsions, emulsion containg only one phase but has a multilayer interface has also been researched. Emulsions with oil droplets surrounded by multilayer interfaces have been shown to have better stability against enviromental stress than single layer emulsions. The multiple layers can be made by electrostatic deposition in which polyelectrolytes are adsorbed on surfaces of oppositely charged colloidal particles. <ref name="weiss"/><ref name="porrasa">M. Porrasa, C. Solansb, C. Gonzáleza, A. Martíneza, A. Guinarta and J.M. Gutiérre, "Studies of formation of W/O nano-emulsions", Colloids and Surfaces A: Physicochemical and Engineering Aspects (2004); 115-118</ref>

	====Association colloids====		====Association colloids====

Schlanbu: /* Nano inside - Delivery systems */

2009-04-08T12:44:53Z

Nano inside - Delivery systems

← Eldre sideversjon		Sideversjonen fra 8. apr. 2009 kl. 12:44
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	==Nano inside - Delivery systems ==		==Nano inside - Delivery systems ==

	"Nano inside" is ~~used as~~ a term for applied nanotechnology in ~~the~~ ingredients ~~in foods~~.<ref name="perceived risks"/> This can either be applied as existing ingredients ~~beeing~~ made into particles in nano scale (1-100nm) which would give the material ~~used~~ new properties, or developing new types of ingredients. These ingredients could for instance give the food higher nutritional values and increased shelf life. As mentioned in the introduction, and also in the health risk section, the current research mainly concerns how the functional ingredients reach their destination~~. This~~ is ~~called a~~ delivery ~~system~~. The delivery system makes sure that the functional ingredient reaches its destination, that ~~the functional ingredient~~ is not degraded during the transport and that the release ~~of the functional ingredient~~ is done properly. Factors affecting the release rate can for example be pH, ionic strength or temperature. It is also important that the delivery system is compatible with other components in the system.<ref name="weiss">Weiss J, Takhistov P, McClements DJ, "Functional Materials in Food Nanotechnology", Journal of Food Science (2006); 71(9): 107-116. </ref>. While most reports published today mainly concerns the future possibilties of the techniques used, there are currently few commercial available products using these application methods listed under. One exception ~~though~~ is a type of bread called Tip Top Up from the Australian company Tip Top. Using nanoencapsulation, tuna fish oil is used for getting Omega 3 acids into the bread. The nanosize particles are not detected by the taste buds and therefore the bread will have no taste of fish oil.<ref name="tiptop">Website: Tip-Top (http://www.tiptop.com.au/), visited 2009.03.21</ref><ref name="chaudry"/>		"Nano inside" is a term for applied nanotechnology in food ingredients.<ref name="perceived risks"/> This can either be applied as existing ingredients made into particles in nano scale (1-100nm) which would give the material new properties, or developing new types of ingredients. These ingredients could for instance give the food higher nutritional values and increased shelf life. As mentioned in the introduction, and also in the health risk section, the current research mainly concerns how the functional ingredients reach their destination, that is, delivery systems. The delivery system makes sure that the functional ingredient reaches its destination, that it is not degraded during the transport and that the release is done properly. Factors affecting the release rate can for example be pH, ionic strength or temperature. It is also important that the delivery system is compatible with other components in the system.<ref name="weiss">Weiss J, Takhistov P, McClements DJ, "Functional Materials in Food Nanotechnology", Journal of Food Science (2006); 71(9): 107-116. </ref>. While most reports published today mainly concerns the future possibilties of the techniques used, there are currently few commercial available products using these application methods listed under. One exception is a type of bread called Tip Top Up from the Australian company Tip Top. Using nanoencapsulation, tuna fish oil is used for getting Omega 3 acids into the bread. Omega 3 is well known for its health benefits, but fish oil is equally known for its unpleasent taste. The nanosize particles are not detected by the taste buds and therefore the bread will have no taste of fish oil.<ref name="tiptop">Website: Tip-Top (http://www.tiptop.com.au/), visited 2009.03.21</ref><ref name="chaudry"/>