Background
The acacia rachii is a leguminous plant, is a traditional Chinese medicine, and has the effects of clearing away heat and toxic materials, promoting the production of body fluid, moistening the lung, inducing diuresis and the like. It is distributed in Fujian, Taiwan, Guangxi, Guangdong, Yunnan provinces and other provinces of China.
The chitosan is a product of natural polysaccharide chitin with partial acetyl removed, and has multiple physiological functions of biodegradability, biocompatibility, nontoxicity, bacteriostasis, cancer resistance, immunity enhancement and the like. The water-soluble chitosan has bactericidal effect on common proteus, bacillus subtilis, escherichia coli, gram-positive bacteria, gram-negative bacteria and the like.
With the discovery of the technology, most of the existing sterilization and antibiosis are carried out by adopting chemical agents, chemical prevention measures such as spraying of chemical synthetic bactericides still dominate the production process of crops, however, the large amount of chemical synthetic bactericides can cause a large amount of harmful bacteria to generate drug resistance, so that the drug effect of the harmful bacteria is gradually weakened. In addition, the chemically synthesized germicides remaining on foods also pose a health hazard.
Publication No. CN 105105279A discloses a food mildew-proof bactericide, which is a bactericide composed of piperine, carbendazim, N-dichlorovinyl salicylamide, butyl hydroxy anisole, tetrabutyl titanate, polyoxyethylene sorbitan fatty acid ester, ketoconazole, prochloraz, litsea cubeba oil and the like, and has good bactericidal and bactericidal effects, but the carbendazim and the prochloraz have low toxicity.
Publication No. CN 103734873A discloses a fresh food bactericide which is composed of dimethyl dicarbonate, calcined calcium, calcium hydroxide, ethanol and sodium lactate, and the bactericide can be used for sterilizing fresh-cut vegetables, but the calcium hydroxide is corrosive.
Therefore, the research of exploring chemical substances which do not harm the environment and human bodies and have high bacteriostatic effect to gradually replace the traditional chemical synthetic bactericide pesticide becomes a research hotspot of researchers.
Disclosure of Invention
Aiming at the problems, the invention provides the composite antibacterial agent of the acacia rattan and the chitosan, which comprises the acacia rattan extract and the chitosan, has good antibacterial property, and is safe, reliable and nontoxic. The antibacterial agent can be applied to fruit and vegetable fresh-keeping, can reduce the use of toxic chemical reagents, can fully ensure the high quality of agricultural products such as fruits and vegetables, ensures the safety of environment and food, and meets the requirement of sustainable development.
The invention is realized by the following technical scheme:
a composite antibacterial agent containing caulis abri extract and chitosan comprises caulis abri extract and chitosan.
Preferably, the mass concentration of chitosan in the composite antibacterial agent is 1-2%. In the technical scheme, the composite antibacterial agent is a mixture of an abrus extract and chitosan, and the chitosan is added into the abrus extract until the mass concentration of the chitosan in the mixture is 1-2%, so that the composite antibacterial agent can be obtained.
Preferably, the molecular weight of the chitosan is less than 1000 Da.
Preferably, the preparation method of the acacia rachii extract comprises the following steps:
(1) soaking caulis abri in water, and decocting with strong fire;
(2) boiling with strong fire, decocting with slow fire, and filtering to obtain filtrate and residue;
(3) taking the filtrate for later use, adding water into the filter residue, decocting with strong fire again until the filter residue is boiled, then decocting with slow fire, and filtering to obtain a second filtrate for later use;
(4) mixing the filtrates, and concentrating with slow fire until the crude drug content of caulis abri is 62.5-500mg/mL to obtain caulis abri extract.
Preferably, in the step (1), the weight part ratio of the acacia rachii and the water is 1:10-15.
Preferably, in the step (3), the weight part ratio of the filter residue to the water is 1: 5-10.
Preferably, the Chinese fire decoction time in the steps (2) and (3) is 25-30 min.
Preferably, the soaking time of the acacia rachii in the step (1) is 25-30 min.
The application of the composite antibacterial agent of the coralhead plant stem and the chitosan in the fruit and vegetable fresh-keeping is provided.
As the optimization of the technical scheme, the application specifically comprises the following steps: the composite antibacterial agent and water are diluted according to the volume ratio of 1:1-3 and then directly and uniformly sprayed on the surfaces of fruits and vegetables.
The ingredients of the acacia rachii extract comprise polysaccharide, organic acid, phenols, amino acid, flavone, protein, steroid and the like.
Compared with the prior art, the invention has the advantages and beneficial effects that:
1. the composite antibacterial agent has good antibacterial property, is safe, reliable and nontoxic, can reduce the use of toxic chemical reagents, can reduce environmental pollution and ensure human health. And the composite antibacterial agent has the advantages of low preparation cost, strong practicability, simple operation and easily obtained raw materials.
2. The composite antibacterial agent has good antibacterial effect, has better effect on inhibiting the dragon fruit pathogenic fungi cactus helminthosporium umbilical than the effect of singly using the abrus extract or the chitosan, and has good fresh-keeping effect on fruits and vegetables.
3. The composite antibacterial agent disclosed by the invention has good inhibitory activity on pathogenic bacteria, can fully ensure the high quality of agricultural products such as fruits and vegetables, ensures food safety and human health, meets the sustainable development requirement, and has a wide application prospect.
Detailed Description
The present invention is further illustrated by the following examples, which are provided only for illustrating the present invention and are not intended to limit the scope of the present invention.
Example 1
The preparation method of the acacia rachii extract comprises the following operation steps:
(1) soaking 100g of acacia rachii in 1000mL of distilled water for 30min, and decocting with strong fire;
(2) boiling with strong fire, decocting with slow fire for 25min, and filtering to obtain filtrate and residue;
(3) taking the filtrate for later use, adding 1000mL of distilled water into the filter residue, decocting with strong fire again until the filter residue is boiled, then decocting with slow fire for 25min, and filtering to obtain a second filtrate for later use;
(4) mixing the two filtrates, and concentrating with slow fire to 196mL to obtain the extract containing 500mg/mL crude drug.
And adding 4g of chitosan into 196mL of the abrus precatorius extract, wherein the molecular weight of the chitosan is less than 1000Da, and the mass concentration of the chitosan in the mixture is 2 percent, so as to obtain the composite antibacterial agent of abrus precatorius aqueous extract with 500mg/mL of abrus precatorius crude drug content and chitosan aqueous solution with the mass concentration of 2 percent.
Example 2
(1) Soaking 100g of acacia rachii in 1500mL of distilled water for 25min, and decocting with strong fire;
(2) boiling with strong fire, decocting with slow fire for 30min, and filtering to obtain filtrate and residue;
(3) taking the filtrate for later use, adding 1000mL of distilled water into the filter residue, decocting with strong fire again until the filter residue is boiled, then decocting with slow fire for 30min, and filtering to obtain a second filtrate for later use;
(4) mixing the filtrates, and concentrating with slow fire to 1500mL to obtain the extract containing 62.5mg/mL crude drug.
Adding 15g of chitosan into 1500mL of the abrus precatorius extract, wherein the molecular weight of the chitosan is less than 1000Da, and the mass concentration of the chitosan in the mixture is 1%, thus obtaining the composite antibacterial agent of abrus precatorius water extract with 62.5mg/mL of abrus precatorius crude drug content and chitosan water solution with 1% of mass concentration.
Example 3
The preparation method of the acacia rachii extract comprises the following operation steps:
(1) soaking 100g of acacia rachii in 1500mL of distilled water for 25min, and decocting with strong fire;
(2) boiling with strong fire, decocting with slow fire for 30min, and filtering to obtain filtrate and residue;
(3) taking the filtrate for later use, adding 500mL of distilled water into the filter residue, decocting with strong fire again until the filter residue is boiled, then decocting with slow fire for 25min, and filtering to obtain a second filtrate for later use;
(4) mixing the filtrates, and concentrating with slow fire to 791mL to obtain caulis abri extract with crude drug content of 125 mg/mL.
Adding 15.8g of chitosan into 791mL of the abrus precatorius extract obtained by the preparation, wherein the molecular weight of the chitosan is less than 1000Da, and the mass concentration of the chitosan in the mixture is 2 percent, thus obtaining the composite antibacterial agent of abrus precatorius aqueous extract with the abrus precatorius crude drug content of 125mg/mL and chitosan aqueous solution with the mass concentration of 2 percent.
Example 4
The preparation method of the acacia rachii extract comprises the following operation steps:
(1) soaking 100g of acacia rachii in 1000mL of distilled water for 25min, and decocting with strong fire;
(2) boiling with strong fire, decocting with slow fire for 25min, and filtering to obtain filtrate and residue;
(3) decocting the filter residue again and filtering, namely adding distilled water with the weight of 500mL of the filter residue into the filter residue, decocting the filter residue again with strong fire until the filter residue is boiled, then decocting the filter residue with slow fire for 25min, and filtering to obtain a second filtrate for later use;
(4) mixing the filtrates, and concentrating with slow fire to 395mL to obtain the extract with crude drug content of 250 mg/mL.
Adding 4g of chitosan into 395mL of the abrus precatorius extract prepared by the above method, wherein the molecular weight of the chitosan is less than 1000Da, and the mass concentration of the chitosan in the mixture is 1 percent, thus obtaining the abrus precatorius water extract with the abrus precatorius crude drug content of 250mg/mL and the composite antibacterial agent of the chitosan water solution with the mass concentration of 1 percent.
Application examples
Preparing 10 PDA culture media with the numbers of A, B, C, D, E, F, G, H, I, J;
adding sterile distilled water with the same volume to the culture medium with the number A as a control group;
adding the abrus thunbergii extract with crude drug content of 62.5mg/mL prepared in example 2 into the culture medium with the number of B;
adding the abrus thunbergii extract with the crude drug content of 125mg/mL prepared in example 3 into the culture medium with the number of C;
adding the abrus thunbergii extract with the crude drug content of 250mg/mL prepared in example 4 into the culture medium with the number of D;
adding the abrus thunbergii extract with the crude drug content of 500mg/mL prepared in example 1 into the culture medium with the number of E;
adding a chitosan aqueous solution with the mass concentration of 1% into the culture medium with the number of F;
adding a chitosan aqueous solution with the mass concentration of 2% into the culture medium with the number G;
adding a chitosan aqueous solution with the mass concentration of 4% into the culture medium with the number of H;
adding the composite antibacterial agent obtained in the example 3 into the culture medium with the number I;
the complex antimicrobial obtained in example 1 was added to the culture medium designated as J.
The group A is added with the same amount of sterile distilled water; other groups are prepared into chitosan culture medium with corresponding crude drug content and corresponding concentration according to the standard that the volume ratio of the solution of the additive substance to the culture medium is 1: 2.
The method comprises the steps of culturing the pitaya pathogenic fungus cactus bipolaris in a culture medium which is added with corresponding substances and is numbered A, B, C, D, E, F, G, H, I, J (strains separated from pitaya are subjected to gene sequencing and gene library comparison), wherein the culture temperature is 28 ℃, the culture time is 72 hours, and observing the pitaya pathogenic fungus cactus bipolaris cultured in each culture medium, wherein the number is shown in figure 1.
The inhibition rate of different agents on the pitaya pathogenic fungus cactus helminthosporium umbilicifolium is calculated, and the result is shown in figure 2.
As can be seen from fig. 2, the inhibition rate of the substance added in the number B on the bipolaris, a pathogenic fungus of pitaya, is 22.79%, the inhibition rate of the substance added in the number C on the bipolaris, a pathogenic fungus of pitaya, is 30.56%, the inhibition rate of the substance added in the number D on the bipolaris, a pathogenic fungus of pitaya, is 43.38%, the inhibition rate of the substance added in the number E on the bipolaris, a pathogenic fungus of pitaya, is 68.22%, the inhibition rate of the substance added in the number F on the bipolaris, a pathogenic fungus of pitaya, is 56.29%, the inhibition rate of the substance added in the number G on the bipolaris, is 61.77%, the inhibition rate of the substance added in the number H on the bipolaris, is 69.69%, and the inhibition rate of the substance added in the number I on the pathogenic fungus of bipolaris, is 69.64.64%, the inhibition rate of the substances added in the number J on the pitaya pathogenic fungus cactus helminthosporium is 72.55%, which shows that the acacia rachii extractive and the chitosan are blended to be used as the composite antibacterial agent, so that the synergistic effect can be achieved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and the like that are within the spirit and principle of the present invention are included in the present invention.