A kind of preparation method of konjac oligosaccharides
Technical field
The present invention relates to a kind of preparation method of konjac oligosaccharides.Belong to the natural polymer chemical field.
Background technology
Rhizoma amorphophalli glucomannan is the main component of konjaku; content in dried konjaku stem tuber is up to 55%~60%; it be by D-glucose and D-seminose by the mol ratio of 1: 1.6 or 1: 1.69 by β-1; 4-pyranoside key bonded mixed polysaccharide; Rhizoma amorphophalli glucomannan has short-chain branch usually; and contain a small amount of ethanoyl; Rhizoma amorphophalli glucomannan is as a kind of natural macromolecule amylose; have many good properties; such as Bc; film-forming properties, biodegradable etc., it is at food; medicine; biochemical; chemical industry; weaving; oil; industries such as makeup all have purposes widely.The molecular weight of Rhizoma amorphophalli glucomannan generally can reach 10
6The order of magnitude, high molecular make it have good thickening property, gelation on the one hand, but make its range of application be subjected to considerable restraint on the other hand.Can degrade to Rhizoma amorphophalli glucomannan, obtain expecting that the konjac oligosaccharides of molecular weight ranges will greatly expand its Application Areas.
Konjac oligosaccharides is the degraded product of Rhizoma amorphophalli glucomannan, is the mixture of a series of oligo-glucomannans, and the different products that obtain with the DeR condition in the source of used preparation raw material are also different.Show konjac oligosaccharides to promoting bifidobacterium growth very effective according to experimentation on animals and clinical study, and can improve the intestinal microflora structure effectively, and its performance and effect are better than lactulose, soybean oligosaccharide and galactosyl and shift oligose.Konjac oligosaccharides also have effects such as control hyperlipidemia, reducing blood-fat, anti-oxidant, raise immunity (Xiang Jinle, Chen Wenpin, Liu Qinjin, " progress of konjac oligosaccharides ", Food Additives Used in China, 2004,1:20-23).Konjac oligosaccharides also can be used as a kind of natural chemical industry, medical material, can be used as functional food additives as konjac oligosaccharides and is applied in the health care food production, and the konjac oligosaccharides derivative can be used as drug development etc., has purposes widely.
Konjac oligosaccharides enzymic degradation konjac glucomannan commonly used obtains, and a kind of is the mannase enzymolysis Rhizoma amorphophalli glucomannan that adopts microbial metabolism to produce, and another kind is directly to extract 'beta '-mannase enzymolysis Rhizoma amorphophalli glucomannan from the konjaku stem tuber.For example adopt β-1, the 4-endoglucanase prepares water-soluble dietary fibre (ZL97107469.0) by konjaku powder, and preparing molecular weight with the cellulase degradation konjaku powder is Konjac Glucomannan (ZL00115963.1) more than 8000.But need to adopt the more expensive enzyme of price in the preparation process, product needs separation purifying technique, and enzyme may remain in the product, technology controlling and process repeated relatively poor.
Employing is arranged in addition
60The report of Co gamma-radiation irradiation Preparation of Chitosan small molecular weight or water-soluble chitosan (publication number CN1563106A), this physical method degrade chitosan, easy to operate, fast and convenient, productive rate height, good reproducibility, molecular weight are easy to control, environmentally friendly, pollute few, with low cost.But source of radiation is not easy to obtain, and the hidden danger of radiocontamination is arranged.
Summary of the invention
Purpose of the present invention is exactly a kind of preparation method who obtains a kind of konjac oligosaccharides of konjac oligosaccharides with the UV-irradiation degraded konjaku powder water-sol who proposes at the deficiency of above-mentioned existence.Little, the good water solubility of konjac oligosaccharides viscosity that is obtained, and the characteristic of maintenance konjak portuguese gansu polyose gel.
Technical scheme provided by the present invention is: a kind of preparation method of konjac oligosaccharides is to degrade the konjaku powder water-sol resultant under UV-irradiation.
The preparation method of above-mentioned konjac oligosaccharides, konjaku powder is mixed with the water-sol that concentration is 0.1-5%wt, place flat Glass Containers to be paved into 1-20mm thickness, with UV-irradiation 0.5-20 minute, product obtained through freeze-drying or spraying drying or with alcohol precipitation after-filtration drying.Product yield is 85-98%.
Above-mentioned UV-light is sent by UV-lamp, and its wavelength region is at 200-450nm.The UV-irradiation time is according to distance, reactant concn, thickness and molecular weight of product decision between used UV-lamp wavelength, power, reactant and fluorescent tube.
The konjac oligosaccharides of gained of the present invention is white or off-white powder, soluble in water, viscosity obviously reduces than konjaku powder, get the konjac oligosaccharides powder and be made into concentration less than 0.05% aqueous solution, measure intrinsic viscosities with Ubbelohde viscometer (internal diameter 0.5-0.6mm) at 30 ± 0.1 ℃, according to the relational expression [η]=5.06 * 10 of the intrinsic viscosity and the molecular weight of konjak portuguese gansu polyose sugar aqueous solution
-4Mw
0.754The molecular weight of calculating konjac oligosaccharides (pray multitude, Li Guangji, Zong Minhua, " controlled degradation of enzyme catalysis Rhizoma amorphophalli glucomannan ", and the polymer journal, 2003,5:650-655).
The konjac oligosaccharides of getting gained of the present invention is made into 5% the water-sol, add yellow soda ash, regulating the pH value is 12,100 ℃ of heating 30 minutes, form konjak gel, illustrate that the konjac oligosaccharides that the present invention obtains has kept Rhizoma amorphophalli glucomannan to heat the characteristic that generates gel under alkaline condition.
Konjac oligosaccharides of the present invention can be controlled its molecular weight in certain limit, has enlarged the range of application of Rhizoma amorphophalli glucomannan, can be used for food, healthcare products, also can be used as industrial chemicals.Preparation technology can be designed to the continuous operation process, can realize continuous, a large amount of industrial production.The present invention has saved complicated loaded down with trivial details separation and purification operation, and it is pure to have reaction system, and equipment is simple, and light source is easy to get, safety non-toxic, and technology is simple and efficient, and is with low cost, and clean environment firendly, product yield height, molecular weight are easy to control, high repeatability and other advantages.
Description of drawings
Accompanying drawing 1 is the FT-IR comparison diagram of konjac oligosaccharides of the present invention and raw material konjaku powder.
Embodiment
The invention will be further described below in conjunction with drawings and Examples.
Accompanying drawing 1 is the FT-IR contrast spectrogram of konjac oligosaccharides and raw material konjaku powder, and oligo-KGM represents konjac oligosaccharides, and KGM represents the raw material konjaku powder.1734cm among the figure
-1The carbonyl absorption peak of acetyl group does not disappear, and illustrates that konjac oligosaccharides has kept the structure of Rhizoma amorphophalli glucomannan, thereby has kept its chemical property yet.
Embodiment one:
Get commercially available konjaku powder and be configured to 0.5% (weight percent) water-sol, it is thick to be paved into 18mm in flat Glass Containers, place ultraviolet lamp (wavelength 254nm, power is 30 watts) descend the 15cm place to shine respectively 1,3,6,9 minute, product is with 4 times of volume 95% ethanol sedimentations, filtration under diminished pressure, vacuum-drying, average yield is 85%.
Embodiment two:
Get commercially available konjaku powder and be configured to 1% (weight percent) water-sol, it is thick to be paved into 5mm in flat Glass Containers, places under the ultraviolet lamp (wavelength 254nm, power are 30 watts) the 20cm place to shine respectively 2,3,4,6 minutes, product freeze-drying, yield are all more than 95%.Get product respectively and be made into the aqueous solution of concentration, measure intrinsic viscosities for 30 ± 0.1 ℃, according to the relational expression [η]=5.06 * 10 of the intrinsic viscosity and the molecular weight of konjak portuguese gansu polyose sugar aqueous solution less than 0.05g/100mL
-4Mw
0.754The molecular weight that calculates konjac oligosaccharides is respectively 89500,26400,13700,9420, and the molecular weight of the konjaku powder of handling without UV-irradiation is 490000.
Embodiment three:
Get commercially available konjaku powder and be configured to 2% (weight percent) water-sol, it is thick to be paved into 4mm in flat Glass Containers, place ultraviolet lamp (wavelength 254nm, power is 30 watts) descend the 20cm place to shine respectively 3,6,9,12 minutes, product is with 4 times of volume 95% ethanol sedimentations, filtration under diminished pressure, vacuum-drying, average yield is 86.3%.Get product respectively and be made into the aqueous solution of concentration, measure intrinsic viscosities for 30 ± 0.1 ℃, according to the relational expression [η]=5.06 * 10 of the intrinsic viscosity and the molecular weight of konjak portuguese gansu polyose sugar aqueous solution less than 0.05g/100mL
-4Mw
0.754The molecular weight that calculates konjac oligosaccharides is respectively 72800,39300,12100,3150, and the molecular weight of the konjaku powder of handling without UV-irradiation is 490000.
Embodiment four:
Get commercially available konjaku powder and be configured to 3% (weight percent) water-sol, it is thick to be paved into 8mm in flat Glass Containers, place ultraviolet lamp (wavelength 365nm, power is 25 watts) descend the 20cm place to shine respectively 2,5,8,11 minutes, product is with 4 times of volume 95% ethanol sedimentations, filtration under diminished pressure, vacuum-drying, average yield is 85.5%.
Embodiment five:
Get commercially available konjaku powder and be configured to 4% (weight percent) water-sol, it is thick to be paved into 6mm in flat Glass Containers, places under the ultraviolet lamp (wavelength 365nm, power are 25 watts) the 20cm place to shine respectively 1,4,8,12 minute, the product freeze-drying, and average yield is 94%.
Embodiment six
Get commercially available konjaku powder and be configured to 5% (weight percent) water-sol, it is thick to be paved into 2mm in flat Glass Containers, place ultraviolet lamp (wavelength 254nm, power is 30 watts) descend the 15cm place to shine respectively 4,7,10,13 minutes, product is with 4 times of volume 95% ethanol sedimentations, filtration under diminished pressure, vacuum-drying, average yield is 88%.
Embodiment seven:
Get commercially available konjaku powder and be configured to 5 part of 5% (weight percent) water-sol, it is thick to be paved into 4mm in flat Glass Containers, place ultraviolet lamp (wavelength 254nm, power is 30 watts) descend the 20cm place to shine 8-19 minute, product is with 4 times of volume 95% ethanol sedimentations, filtration under diminished pressure, vacuum-drying, average yield is 85.9%.
Embodiment eight:
Get commercially available konjaku powder and be configured to 4 part of 5% (weight percent) water-sol, it is thick to be paved into 3mm in flat Glass Containers, places ultraviolet lamp (wavelength 254nm, power is 30 watts) descend the 20cm place to shine 8-19 minute, regulating the pH value with yellow soda ash is 12, and heating is 30 minutes in the boiling water bath, all generates gel.
Embodiment nine:
Get commercially available konjaku powder and be configured to 1%, 2% (weight percent) water-sol respectively, it is thick to be paved into 8mm in flat Glass Containers, place ultraviolet lamp (wavelength 254nm, power is 30 watts) descend the 18cm place to shine 2-8 minute, regulating the pH value with yellow soda ash is 12, heating is 2 hours in 60 ℃ of water-baths, all generates gel.