A kind of titania nanoparticles and lichee nanometer fresh-keeping agent
Technical field
The invention belongs to the fruit freshness preserving technical field, be specifically related to a kind of titania nanoparticles and the application aspect lichee fresh-keeping thereof.
Background technology
The lichee ripening stage, the fruit utmost point is storage tolerance not on the occasion of summer High Temperature season.The annual loss caused because rotting of lichee accounts for more than 20% of ultimate production.Therefore after adopting, lichee must carry out preservation and freshness.At present, at lichee quick freezing and cold preserving fresh-keeping aspect, substantially can guarantee fruit storage half a year or longer time.Yet, aspect normal-temperature fresh-keeping, not yet obtain important breakthrough.At present, both at home and abroad in the screening and the application that mainly bias toward sanitas, preservation agent aspect room temperature storage research, but soaking time generally is no more than 7~8d, and anticorrosion in conjunction with conventional medicine, as benomyl, TBZ, sterilizing prestige etc.Because these medicines have certain toxicity and residual quantity, can affect HUMAN HEALTH.The external main sulphuring method that adopts is carried out the lichee normal-temperature fresh-keeping, though can effectively keep fruit color, to some fungi, can not kill fully, causes the mouthfeel variation, affects people's physical and mental health.Therefore, be badly in need of the preservation agent of a kind of nontoxic, anti-dehydration of development, anti-brown stain, anticorrosion, disease prevention and prolongation aging.
Current, Development of Nanometer Material is rapid, and nano material has the excellent specific property that much is different from conventional material, as character such as high-specific surface area, quantum effect, special light, thermal and magnetics.Therefore, how fully effectively by Application of micron in Food science, and development and utilization effectively, be one of direction of Application of micron.
At present, the nano material that is applied to the preserving fruit and vegetable utilizing aspect mainly contains nano silicon oxide, nano titanium oxide, silver-colored based nano-material etc.Appropriate nanometer SiOx particle adds can form nano antibacterial film, utilizes siloxane bond to CO
2And O
2Absorption, dissolving, diffusion and release action, regulate the inside and outside CO of film
2And O
2Exchange capacity, thereby suppress the fruits and vegetables respiratory intensity, play the effect of fresh-keeping water conservation.Nano-anti-oxidation agent, antiseptic-germicide are applied to fresh-keeping packaging material and can improve the fresh-keeping effect of fresh fruit of vegetables and extend fresh keeping time.Nano series silver powder can effectively extend the antibiotic time, and the ethene that the accelerated oxidation fruits and vegetables discharge reduces the content of ethene in packing, thereby reaches good fresh-keeping effect.And nano-TiO
2Have good photocatalysis performance, it can resolve into the oxidation of ethylene produced in fruit vegetables storing carbonic acid gas and water on the one hand; On the other hand can killing bacteria etc. microorganism, therefore can effectively extend the preserving fruit and vegetable utilizing time.Bibliographical information nano titanium oxide fruit and vegetable fresh-keeping agent is arranged, normally that trolamine is water-soluble, add nano titanium oxide, high-speed stirring, nano titanium oxide is dispersed in the trolamine aqueous solution, and be heated to 90 ℃, again carnauba wax and oleic acid are mixed, be heated to 90 ℃, stir, by the triethanolamine solution of nano titanium oxide and carnauba wax with the oleic acid mixed solution is mixed obtains a kind of nanometer fruits and vegetables preservation agent, can be sprayed at respectively apple, oranges and tangerines, banana, cherry, tomato, long eggplant, on the various fruits and vegetables such as watermelon, forming glossiness on its surface films for fresh-keeping, the Patent Application Publication that number of patent application is 200610155124.2 a kind of nanometer fruits and vegetables normal temperature antistaling agent and preparation method thereof, described preservation agent is comprised of the raw material of following weight per-cent: nano titanium oxide 0.5~10%, nanometer silver titanium 0.01~1%, white mica 5~20%, ethyl p-hydroxybenzoate and, to mixture 0.05~1%, iron powder 1~5%, cinnamic aldehyde 0.001~0.01%, the gac 2~7% of hydroxyl propyl formate, all the other are carrier.But above-mentioned preservation agent all adopts organic components, organism is attached to the lichee surface for a long time, by permeating, easily enters in pulp to produce untoward reaction, affects HUMAN HEALTH.
Summary of the invention
An object of the present invention is to overcome the deficiency of existing nanometer preservation technique, a kind of titania nanoparticles of pure water soluble is provided, its preparation method is simple, and any organic pollutant.By improving its antibiotic fresh-keeping function reached lichee under visible ray after modification, extend the fresh-keeping life-span.
Another object of the present invention is described titania nanoparticles to be combined with crude antistaling agent obtain the nanometer fresh-keeping agent that a kind of ecological, environmental protective has better normal temp fresh-keeping function.
Purpose of the present invention is achieved by the following technical programs:
A kind of titania nanoparticles is provided, and average particle size particle size is 6~10nm, and crystalline phase is Anatase, and the precipitation that adopts inorganic titanium salt to be hydrolyzed under alkaline condition to obtain, with after oxidizer treatment, adds the precious metal ion insulation to process and obtains.Nano particle natural stability ground Monodispersed is in the aqueous solution, without any organic dispersing agent and stablizer.The part by weight that preferred scheme is inorganic titanium salt, oxygenant and precious metal chemical complex is 1~2: 10~20: 0.05~0.1.
Inorganic titanium salt preferably sulfuric acid oxygen titanium of the present invention, titanium tetrachloride or titanium sulfate; The preferred Ag of described precious metal ion, the metal ions such as Ce, Gd, can select compd A gNO
3, Ce (NO
3)
3, Gd (NO
3)
3Deng; Described oxygenant is a kind of in nitric acid or hydrogen peroxide.
Described hydrolysis is that to be hydrolyzed into the pH value be 4~8.
The preparation method of titania nanoparticles of the present invention comprises the following steps:
(1) inorganic titanium salt being hydrolyzed under alkaline condition to pH is 4~8, then after centrifugal treating, obtains white precipitate;
(2) white precipitate step (1) obtained obtains brown transparent liquid with after deionized water wash 2~3 times by oxidizer treatment, then standing 6~12h;
(3) precious metal chemical complex is added in the described brown transparent liquid of step (2), 4~8h is processed in 90~100 ℃ of insulations, obtains the oyster white nano titanic oxide sol; Cooling standby.
Titanium dioxide nanoparticle mass percent content in described titania nanoparticles solution is 1~8%, the size average out to 6~10nm of nano particle.
The present invention provides a kind of lichee nanometer fresh-keeping agent simultaneously, comprise above-mentioned oyster white nano titanic oxide sol, water soluble dispersing agent and fresh litchi liquid, described water soluble dispersing agent is Sodium hexametaphosphate 99 or tripoly phosphate sodium STPP, and described fresh litchi liquid is that the fresh litchi leaf is added to concentrated the preparing of aqueous solution process that water boil obtains; By weight, water soluble dispersing agent is 0.3~1.5% of lichee nanometer fresh-keeping agent gross weight; Described fresh litchi liquid is 3~10% of preservation agent gross weight;
The preparation method of described lichee nanometer fresh-keeping agent comprises the following steps:
(A) add water soluble dispersing agent toward cooled oyster white nano titanic oxide sol, stir, obtain scattered titania nanoparticles solution;
The fresh litchi leaf is added to the aqueous solution that water boil obtains and after concentrated, make fresh litchi liquid;
(B) fresh litchi liquid is added in the titania nanoparticles solution that above-mentioned steps (A) prepares, after stirring and get final product.
The weight ratio of the described fresh litchi leaf of step (A) and water is 1~10: 1; Boiling time preferably 0.5 hour~1 hour; Can be concentrated into half left and right of original volume.
The using method of described lichee nanometer fresh-keeping agent is:
In the container that nanometer fresh-keeping agent of the present invention is packed into shower nozzle, then evenly be sprayed on litchi fruits surface 1~2 time, the litchi fruits of handling well is positioned in packing box and gets final product.
Beneficial effect of the present invention:
The present invention is directed to the deficiencies in the prior art, the invention provides a kind of water-based inorganic nano titanium dioxide antistaling agent for litchi, adopt the dispersed nano particle of Hydrothermal Synthesis, the anatase-phase nano titanium dioxide particle that Hydrothermal Synthesis average particle size particle size is 6~10nm.In preservation agent without any objectionable constituent.In order further to improve its visible light catalysis activity, also adopted doping techniques modified nano-titanium dioxide particle, improve its can by under light to the inhibition of lichee surface microorganism or kill and the effects such as degraded of the gases such as ethene that lichee metabolism discharges, it has photocatalytic activity preferably, can effectively kill the bacterium on lichee surface and remove the ethylene gas that metabolism discharges, thering is the long-period freshness preserving function.The nano titanium oxide semiconductor material is that 10nm can absorb UV-light when following and produces free carrier in particle size, these current carrier activity are very strong, oxygen and the water molecules that can exist with particle surface form free radical, these free radicals can enter its interior tissue of microorganism internal sabotage, thus killing bacteria.Simultaneously, these free radicals can destroy the two keys in organism, fragrant chain and make the organism fission and generate carbonic acid gas and water, thereby reach well anticorrosion and suppress the effect such as after-ripening.Nano-titania photocatalyst preservation agent of the present invention is originally as inorganics, and nontoxic, pollution-free, for the environmental protection preparation, without any side effects, after 30~60 days, litchi fruits, without any peculiar smell and variable color, keeps original fresh taste.Its cost is that per kilogram lichee preservation agent used is 0.05 yuan of left and right, has that fresh keeping time is long, cost is low, keeps preferably the beneficial effect such as the delicious taste of lichee, has great application and promotion prospect.
The accompanying drawing explanation
The SEM figure of Fig. 1 nano particle of the present invention
The X-ray diffractogram of nano particle in Fig. 2 nanometer fresh-keeping agent of the present invention
Embodiment
Further describe the present invention below in conjunction with specific embodiment.The test method of using in following embodiment and equipment if no special instructions, are ordinary method; The raw material used if no special instructions, is the raw material that can obtain from commercial channels.
Embodiment 1
By 10gTiCl
4Add in 500ml water, regulating the pH value with strong aqua is 6.2, obtain white precipitate 50g after centrifugal treating (4000r/min), then sedimentable matter is added to the 500ml deionized water with after deionized water wash 2 times, then add 10ml nitric acid (being diluted to volume by volume concentration is 30~50%) to obtain transparent liquid after fully stirring 1h; After standing 6h by 0.5g AgNO
3Add in transparent liquid, process 4h through 95 ℃ of insulations and obtain the oyster white nano titanic oxide sol, the gained titania nanoparticles is of a size of 6~10nm, and grain-size is Anatase, and the SEM figure of nano particle is shown in shown in accompanying drawing 1.
The solution A that adds the 1g Sodium hexametaphosphate 99 to stir scatteredly after the oyster white nano titanic oxide sol is cooling;
The 1g Lychee leaf is added to 10ml water, boil after 0.5h to obtain the aqueous solution, adopt ordinary method to be concentrated into the 5ml left and right, obtain fresh litchi liquid 5g;
2g fresh litchi liquid is added in the scattered solution A of 2g, obtain the fresh lichee nanometer fresh-keeping agent after stirring.The pH value of the preservation agent made is 5~8; Without organic components, it is the environment-friendly type nano preservation agent.
By nanometer fresh-keeping agent of the present invention, evenly be sprayed on the fresh lichee fruit surface, spray twice, then the fresh litchi fruit is placed in to conventional packaging vessel (need not seal), open container after 30 days, find that the phenomenons such as any peculiar smell, variable color, weakness do not appear in litchi fruits.
Embodiment 2
By 10gTiOSO
4Add in 500ml water, regulating pH with strong aqua is 6.8, after centrifugal treating, obtain obtaining white precipitate 56g after (4500r/min), add the 500ml deionized water with after deionized water wash white precipitate 3 times, use again the hydrogen peroxide of 10ml 30% (volume by volume concentration) concentration to obtain transparent liquid after fully stirring 1h, then standing 6h, by 1g Ce (NO
3)
3Add wherein, by 95 ℃ of insulations, process 6h, obtain the oyster white nano titanic oxide sol, the nanometer titanium dioxide titanium solution that adds the 1.5g Sodium hexametaphosphate 99 to stir scatteredly after cooling;
Described nanoparticle size adopts transmission electron microscope to detect and obtains, and crystalline phase is measured by X ray crystalline diffraction instrument, and the titania nanoparticles mean sizes is 6~10nm, and crystalline phase is Anatase.
The 1g Lychee leaf is added to 12ml water, boil the aqueous solution obtained after 0.5h, be concentrated into the 5ml left and right and obtain fresh litchi liquid 5g.
2g fresh litchi liquid is added in the scattered scattered nanometer titanium dioxide titanium solution of 3g, obtain the fresh lichee nanometer fresh-keeping agent after stirring.
By nanometer fresh-keeping agent of the present invention, evenly be sprayed on and need fresh-keeping fresh lichee fruit surface twice, then be placed in packaging vessel, open after 45 days and find that the phenomenons such as any peculiar smell, variable color, weakness do not appear in litchi fruits.
Embodiment 3
By 10gTi (SO
4)
2Add in 500ml water, regulating pH with strong aqua is 6.0, obtain white precipitate after centrifugal treating, then sedimentable matter is added to the 500ml deionization with after deionized water wash 2 times, obtain transparent liquid with the hydrogen peroxide of 10ml 30% concentration after fully stirring 1h again, then after static 6h by 0.8g Gd (NO
3)
3Add wherein by after 95 ℃ of insulation processing 6h, obtaining the oyster white nano titanic oxide sol; The nanometer titanium dioxide titanium solution that adds the 1.2g tripoly phosphate sodium STPP to stir scatteredly after cooling;
Described nanoparticle size adopts transmission electron microscope to detect and obtains, and crystalline phase is measured by X ray crystalline diffraction instrument, and the titania nanoparticles mean sizes is 6~10nm, and crystalline phase is Anatase.
The 1g Lychee leaf is added to 12ml water, boil the aqueous solution obtained after 30min, be concentrated into the 4ml left and right and obtain fresh litchi liquid 4.2g.
2g fresh litchi liquid is added in the scattered nanometer titanium dioxide titanium solution of 3g, obtain the fresh lichee nanometer fresh-keeping agent after stirring.
By nanometer fresh-keeping agent of the present invention, evenly be sprayed on and need twice of fresh-keeping fresh lichee fruit surface.Then be placed in packaging vessel, open after 55 days and find the phenomenons such as any peculiar smell and variable color do not appear in litchi fruits, weak.