Application of macadamia nut green peel in preparation of antibacterial agent

Abstract

The invention discloses application of macadamia nut green peel in preparation of an antibacterial agent, and belongs to the technical field of application of antibacterial agents. The invention finds that the macadamia nut green peel has an antibacterial effect for the first time, and the preparation method of the antibacterial agent comprises the following steps: cleaning the macadamia nut green peel, drying, crushing, sieving, collecting powder on the sieve, adding distilled water, carrying out a hydrothermal reaction, carrying out suction filtration after the reaction is finished, and collecting filtrate, so as to obtain the antibacterial agent. The antibacterial agent prepared from the macadamia nut green peel can effectively inhibit escherichia coli and staphylococcus aureus, and a new way is provided for resource utilization of the macadamia nut green peel.

Description

Technical Field

[0001] The invention discloses an application of macadamia nut green peel in preparing an antibacterial agent, belonging to the technical field of antibacterial agent application. Background Art

[0002] Macadamia (Macadamia integrifolia), also known as macadamia nuts, are highly favored internationally for their rich nutrition, delicate taste and delicious taste. They were introduced to China in the 1970s. At present, my country is the world's largest macadamia nut grower. As of 2023, the planting area in Yunnan Province reached 3.79 million mu, accounting for 81.77% of the country and 49.22% of the world, ranking first in the world. Macadamia nut fruit is mainly composed of three parts: green peel, shell and kernel. The green peel accounts for 45% to 60% of the fresh fruit mass. Therefore, a large amount of green peel by-products are produced in the post-harvest processing and primary processing links. However, most of them are discarded, resulting in a serious waste of resources. Therefore, the comprehensive utilization of macadamia nut green peel research has important practical significance for saving resources and improving industrial efficiency.

[0003] At present, there are very few research reports using macadamia nut green peel as the main raw material, and there are few related papers and patents, and they mainly study the preparation of antioxidants or organic fertilizers, such as "A macadamia nut green peel antioxidant and its preparation method (Invention Publication 202010380213.7)"; "A toner with macadamia protein peptide and green peel extract as active ingredients and its preparation method (Invention Publication 201810608248.4)"; "A preparation method of green peel organic fertilizer, preparation method and application of organic-inorganic compound fertilizer (Invention Publication 202311185241.3)" and other patents. It can be seen that there is still a large gap in the development and utilization of macadamia green peel antibacterial agents. Summary of the invention

[0004] In order to make more effective use of macadamia nut green peel, the present invention aims to provide a use of macadamia nut green peel in the preparation of an antibacterial agent.

[0005] Preferably, the preparation method of the antibacterial agent comprises the following steps:

[0006] (1) Wash the green peel of macadamia nuts, dry it, crush it, sieve it, and collect the powder on the sieve to obtain the coarse powder of green peel of macadamia nuts.

[0007] (2) The macadamia nut green peel coarse powder is mixed with distilled water, and then subjected to hydrothermal reaction after ultrasonic treatment. After the hydrothermal reaction, the filtrate collected by suction filtration is the antibacterial agent.

[0008] Preferably, the mesh size of the sieve used for sieving in step (1) is 100-200 mesh.

[0009] Preferably, in step (2), the solid-to-liquid ratio of the macadamia nut green peel coarse powder to distilled water is 1:10 to 30, expressed in g:mL.

[0010] Preferably, the hydrothermal reaction in step (2) is carried out at 140-220° C. for 6-24 hours.

[0011] Beneficial effects of the present invention

[0012] (1) The present invention is the first to discover a new use of macadamia nut green peel, and provides a new method for resource utilization of macadamia nut green peel.

[0013] (3) The maximum antibacterial rate of the macadamia nut green peel prepared by the method of the present invention against Escherichia coli reached 90.2%, and the antibacterial rate against Staphylococcus aureus reached 44.6%. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The antibacterial effect of the antibacterial agent prepared in Example 1 on Escherichia coli.

[0015] Figure 2 The antibacterial effect of the filter residue obtained in Example 1 on Escherichia coli.

[0016] Figure 3 The antibacterial effect of the antibacterial agent prepared in Comparative Example 2 on Escherichia coli.

[0017] Figure 4 The figure shows the antibacterial effect of the filter residue obtained in the comparative example on Escherichia coli.

[0018] Figure 5 The antibacterial effect of the antibacterial agent prepared in Comparative Example 3 on Escherichia coli.

[0019] Figure 6 The antibacterial effect of the filter residue obtained in Comparative Example 3 on Escherichia coli.

[0020] Figure 7 The antibacterial effect of untreated macadamia nut green peel powder on Escherichia coli.

[0021] Figure 8 The antibacterial effect of the antibacterial agent prepared in Example 1 on Staphylococcus aureus.

[0022] Fig. 9 The antibacterial effect of the filter residue obtained in Example 1 on Staphylococcus aureus.

[0023] Fig.10 The antibacterial effect of the antibacterial agent prepared in Comparative Example 2 on Staphylococcus aureus.

[0024] Fig.11 The figure shows the antibacterial effect of the filter residue obtained in the comparative example on Staphylococcus aureus.

[0025] Fig.12 The antibacterial effect of the antibacterial agent prepared in Comparative Example 3 on Staphylococcus aureus.

[0026] Fig.13 The antibacterial effect of the filter residue obtained in Comparative Example 3 on Staphylococcus aureus.

[0027] Fig.14 The antibacterial effect of untreated macadamia nut green peel powder against Staphylococcus aureus. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0029] Example 1

[0030] A method for preparing an antibacterial agent using macadamia nut green peel, comprising the following steps

[0031] (1) Wash the green peel of macadamia nuts, dry it in an oven, put it into a grinder for grinding, pass it through a 200-mesh sieve, and collect the powder on the sieve to obtain the coarse powder of the green peel of macadamia nuts.

[0032] (2) 1.0 g of macadamia nut green peel coarse powder was placed in a small beaker containing 10 mL of distilled water to obtain a suspension. The suspension was subjected to ultrasonic treatment at room temperature for 20 min, followed by hydrothermal reaction at 180° C. for 12 h, and then naturally cooled to room temperature. The filtrate obtained by suction filtration was the antibacterial agent, and the filter residue was retained for later use.

[0033] Example 2

[0034] A method for preparing an antibacterial agent using macadamia nut green peel, comprising the following steps

[0035] (1) Wash the green peel of macadamia nuts, dry it in an oven, and then grind it in a grinder. Then, sieve it through a 150-mesh sieve, and collect the powder on the sieve to obtain the coarse green peel powder of macadamia nuts.

[0036] (2) 1.0 g of macadamia nut green peel coarse powder was placed in a small beaker containing 20 mL of distilled water to obtain a suspension. The suspension was subjected to ultrasonic treatment at room temperature for 20 min, followed by hydrothermal reaction at 140° C. for 24 h, and then naturally cooled to room temperature. The filtrate obtained by suction filtration was the antibacterial agent, and the filter residue was retained for later use.

[0037] Example 3

[0038] A method for preparing an antibacterial agent using macadamia nut green peel, comprising the following steps

[0039] (1) Wash the green peel of macadamia nuts, dry it in an oven, put it into a grinder for grinding, pass it through a 100-mesh sieve, and collect the powder on the sieve to obtain a coarse powder of the green peel of macadamia nuts.

[0040] (2) 1.0 g of macadamia nut green peel coarse powder was placed in a small beaker containing 30 mL of distilled water to obtain a suspension. The suspension was subjected to ultrasonic treatment at room temperature for 20 min, followed by hydrothermal reaction at 220° C. for 6 h, and then naturally cooled to room temperature. The filtrate obtained by suction filtration was the antibacterial agent, and the filter residue was retained for later use.

[0041] Comparative Example 1

[0042] In comparison, the only difference between this comparative example and Example 1 is that the macadamia nut green peel antibacterial agent is prepared using the sieved powder, comprising the following steps:

[0043] (1) Wash the green peel of macadamia nuts, dry it in an oven, put it into a grinder for grinding, pass it through a 200-mesh sieve, and collect the powder under the sieve to obtain the fine powder of macadamia nut green peel.

[0044] (2) 1.0 g of macadamia nut green peel fine powder was placed in a small beaker containing 10 mL of distilled water to obtain a suspension. The suspension was subjected to ultrasonic treatment at room temperature for 20 min, followed by hydrothermal reaction at 180° C. for 12 h, and then naturally cooled to room temperature. The filtrate obtained by suction filtration was the antibacterial agent, and the filter residue was retained for later use.

[0045] Comparative Example 2

[0046] As a comparison, the difference between this comparative example and Example 1 is that the antibacterial agent is prepared by a common immersion method, including the following steps:

[0047] (1) Wash the green peel of macadamia nuts, dry it in an oven, put it into a grinder for grinding, pass it through a 200-mesh sieve, and collect the powder on the sieve to obtain the coarse powder of the green peel of macadamia nuts.

[0048] (2) Take 1.0 g of macadamia nut green peel coarse powder in a small beaker filled with 10 mL of distilled water to obtain a suspension. After stirring at room temperature for 48 hours, the filtrate obtained by suction filtration is the antibacterial agent, and the filter residue is retained for later use.

[0049] Test Example 1

[0050] The macadamia nut green peel antibacterial agent prepared in Example 1 and Comparative Examples 1-2 and the retained filter residue were used for antibacterial test, and all macadamia nut green peel antibacterial agents and filter residues to be tested were referred to as test samples.

[0051] The experiment selected Gram-positive bacteria Staphylococcus aureus (S. aureus, CCTCC AB 91093) and Escherichia coli (E. coli, CCTCCAB 204033) as experimental strains for antibacterial detection.

[0052] The preparation method of the culture medium used in the experiment is as follows:

[0053] LB agar medium: 5 g tryptone, 2.5 g yeast powder, 5 g sodium chloride, 500 mL distilled water, 7.5 g agar;

[0054] LB liquid culture medium: 5 g tryptone, 2.5 g yeast powder, 5 g sodium chloride, and 500 mL distilled water.

[0055] The specific test steps are as follows:

[0056] (1) Add the strain to sterile LB liquid medium and culture it to a concentration of 5×10 6 CFU / mL of bacterial suspension, when the concentration of cell suspension is greater than 5×10 6 CFU / mL, dilute with sterile water.

[0057] (2) 5 mg of the sample to be tested (the macadamia green peel antibacterial agent and filter residue prepared in all embodiments and comparative examples) was mixed with 10 mL of the diluted bacterial solution and placed in a sterile test tube to prepare a suspension, which was incubated on a shaker at 37°C and 200 rpm for 30 min, 100 μL was dripped into a culture dish with LB agar medium, and the bacterial solution was evenly spread on the culture medium by the spread plate method, and the culture dish was placed in a constant temperature incubator and cultured for 18 to 24 h.

[0058] (3) After cultivation, the antibacterial rate of each sample was calculated using the colony counting method.

[0059] The calculation formula is as follows:

[0060] After testing, the antibacterial effects of all the samples in the embodiments and comparative examples on Escherichia coli are as follows: Figure 1 to Figure 6 As shown in the figure (in all figures, A represents the blank control, and B represents the experimental group), it can be seen from the figure that the antibacterial effect of the antibacterial agent prepared by the method of the present invention on Escherichia coli is significantly better than that of the antibacterial agent prepared by other methods; the antibacterial effect of the samples to be tested in all embodiments and comparative examples on Escherichia coli is as shown in the figure. Figure 8 to Figure 13 As shown (in all figures, A represents the blank control and B represents the experimental group), it can be seen from the figure that the antibacterial effect of the antibacterial agent prepared by the method of the present invention on Staphylococcus aureus is significantly better than that of the antibacterial agents prepared by other methods.

[0061] The calculated antibacterial rates of the samples to be tested in Example 1 and Comparative Examples 1-2 are shown in Table 1.

[0062] Table 1 Antibacterial rate of samples tested in embodiments and comparative examples

[0063]

[0064] It can be more intuitively seen from Table 1 that the antibacterial agent prepared by the method described in the present invention has the best antibacterial effect on Escherichia coli.

[0065] The antibacterial effects of the antibacterial agents prepared in Examples 2 and 3 were similar to those in Example 1.

[0066] Finally, the same method was used to test the antibacterial effect of macadamia nut green peel coarse powder, and it was found that the antibacterial effect was not good. Figure 7 and Fig.14 As shown, the antibacterial rate is almost 0%.

Claims

1. An application of macadamia nut green peel in the preparation of an antibacterial agent.

2. The use according to claim 1, characterized in that: The preparation method of the antibacterial agent comprises the following steps: (1) washing the green peel of macadamia nuts, drying it, crushing it, sieving it, and collecting the powder on the sieve to obtain a coarse powder of the green peel of macadamia nuts; (2) The macadamia nut green peel coarse powder is mixed with distilled water, subjected to ultrasonic treatment and then subjected to hydrothermal reaction. After the hydrothermal reaction is completed, the mixture is cooled to room temperature, and the filtrate collected by suction filtration is the antibacterial agent.

3. The use according to claim 2, characterized in that: The mesh size of the sieve used for sieving in step (1) is 100-200 meshes.

4. The use according to claim 2, characterized in that: In step (2), the solid-to-liquid ratio of the macadamia nut green peel coarse powder to distilled water is 1:10 to 30, in units of g:mL.

5. The use according to claim 2, characterized in that: The hydrothermal reaction conditions in step (2) are 140-220° C. for 6-24 hours.

Images