CN115088762A - Slow-release sprout inhibitor, application in potato sprout inhibitor and preparation method - Google Patents

Abstract

The invention belongs to the field of agricultural product storage, and particularly relates to a slow-release sprout inhibitor for inhibiting potato sprouting, application and a preparation method thereof. The bud inhibitor is prepared from fucoidin and methyl salicylate as raw materials, wherein the weight volume ratio of the fucoidin to the methyl salicylate is 1 g: 2 mL. The preparation method of the bud inhibitor comprises the steps of dissolving fucoidin, adding emean gentamicin methyl salicylate, promoting dissolution by adopting an ultrasonic-microwave combination method, and mixing with a calcium chloride solution to obtain the hydrogel. The potato slow-release sprout inhibitor prepared by the specific method has the advantages of non-toxic and harmless raw materials, low cost and simple preparation process steps, solves the problems of easy oxidation, high release speed and non-durable drug effect of methyl salicylate, has obvious sprout inhibition effect on potato tubers in the dormancy stage, and is strong in practicability and easy to popularize and apply in a large scale.

Description

Slow-release sprout inhibitor, application in potato sprout inhibitor and preparation method

technical field

The invention belongs to the field of agricultural product storage, and in particular relates to a slow-release sprout inhibitor for inhibiting potato germination, and also relates to an application and a preparation method of the above sprout inhibitor.

Background technique

Potato is an annual herb of the Solanaceae family. It contains nutrients such as starch, protein, fat, crude fiber, minerals and vitamins. It is listed as the fourth staple food and promoted. Germination is the main reason for the loss of potatoes during storage, which leads to the loss of nutrients and the production of toxic solanine. Therefore, effectively inhibiting tuber germination is an urgent problem to be solved in the potato industry. At present, there are two main ways to inhibit potato germination in commercial applications. One is to use refrigeration and place it under 2-4 ℃ refrigeration conditions, which can prolong the dormancy period and will not germinate. Once out of the warehouse and entering the logistics link, it will germinate quickly. The second is to use low temperature in combination with sprouting inhibitor. At present, mainly chloraniline (CIPC, Dike) is mainly used. There are chloraniline powder, aerosol and emulsifiable concentrate that can be purchased on the market. It has a very good bud-inhibiting effect, but the use of chloraniline on potatoes that have passed the dormant period has poor bud-inhibiting effect, and chloraniline is a herbicide in pesticides, which has mutagenic and carcinogenic effects on humans and other animals. It has been banned in the US and EU, and China has enacted regulations that will phase out its use. The development of safe and efficient germination inhibitor products for potatoes after dormancy release and storage is imminent.

Studies have shown that the essential oils of peppermint, caraway, dill, spearmint, jasmine, thyme, cinnamon and other plants have a significant inhibitory effect on potato germination. Methyl salicylate is the main component of wintergreen essential oil, and its anti-budding effect on potato has not been reported yet. Plant essential oils are easily affected by air, light and temperature, resulting in easy oxidation, rapid volatilization, high dosage and high price, which limit their application.

At present, the embedding of essential oils is mainly based on microcapsules and microspheres. Hydrogels are hydrophilic polymers formed by physical or chemical cross-linking, which are widely used in the fields of drug delivery, biomedicine, tissue engineering and food industry. Compared with traditional hydrogel materials, polysaccharide hydrogel materials such as cellulose, sodium alginate, chitosan, xanthan gum, hyaluronic acid, konjac glucomannose, pectin, etc. have good biocompatibility and good biocompatibility. degradability, thus becoming a research hotspot.

Fucoidan, also known as fucoidan, fucoidan, fucoidan sulfate, the main monosaccharide is L-fucose, mainly derived from brown algae, has antioxidant, anti-tumor, anti-aging, anti-virus and other effects , is developed for use in health products and beverages, and is a food-grade marine active substance. At present, the research on fucoidan is mainly based on the application of active substances, and the products on the market are mainly based on the supply of raw materials, while ignoring its gel properties as a polysaccharide. The existing potato germination inhibitors are mainly powders, sprays, and microcapsules, and the release rate is rapid and thorough, and cannot be continuously supplied.

Therefore, it is necessary to invent a potato sprouting inhibitor that can release rapidly, continuously supply medicine and has excellent sprouting inhibitory effect.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems, the present invention provides a potato slow-release sprouting inhibitor, and also provides a preparation method of the above-mentioned sprouting inhibitor.

In the present invention, the slow-release sprouting inhibitor obtained by preparing fucoidan and methyl salicylate is creatively applied to inhibiting potato germination, and the sprouting inhibitory effect is excellent. Specifically, the combination of fucoidan and methyl salicylate is The weight-to-volume ratio is 1 g:2 mL.

The present invention also provides that a slow-release sprouting inhibitor is prepared from slow-release carrier fucoidan and methyl salicylate, an active sprouting inhibitor. In the slow-release sprouting inhibitor, the weight-to-volume ratio of fucoidan to methyl salicylate is 1 g: 2 mL.

More specifically, the above-mentioned slow-release germination inhibitor for inhibiting potato germination is obtained by dissolving fucoidan, adding methyl salicylate and an emulsifier to prepare an emulsion, and then adding calcium chloride to prepare an emulsion.

The preparation method of above-mentioned slow-release sprouting inhibitor, comprises the following steps:

S1: take fucoidan and pour it into distilled water, place it in a magnetic stirrer to heat and dissolve, add Tween and methyl salicylate respectively, and heat and stir at a high speed for 15 minutes to prepare a uniform emulsion;

S2: suck the emulsion in S1 into a syringe, slowly add it dropwise to the calcium chloride solution, and let it stand at room temperature;

S3: Quickly rinse with distilled water, and dry the surface moisture with filter paper to obtain a potato slow-release germination inhibitor.

Preferably, the preparation method of the above-mentioned potato slow-release sprout inhibitor, comprises the following steps:

S1: Take 0.35 g of fucoidan and put it in 20 mL of distilled water, heat it to 80 °C in a magnetic stirrer to dissolve, add 30 μL of Tween and 0.7 mL of methyl salicylate respectively, and heat to 60 °C for high-speed stirring for 15 minutes to prepare a homogeneous emulsion;

S2: suck the emulsion in S1 into a 1mL syringe, slowly add it dropwise to the calcium chloride solution, and let it stand for 2h at room temperature;

S3: Quickly rinse with distilled water for 3 times, and dry the surface moisture with filter paper to obtain a potato slow-release germination inhibitor.

As a kind of preferred mode, the preparation method of potato slow-release sprout inhibitor, comprises the following steps:

S1: Take 0.2g of fucoidan and put it in 40mL of distilled water, add 40μL of Tween and 0.4mL of methyl salicylate in turn, at room temperature, use the ultrasonic-microwave combined method to promote dissolution, ultrasonic power 400W, microwave power 900W, treatment time 2min to form a uniform white emulsion;

S2: suck the above white emulsion into a 1mL syringe, slowly add it dropwise to a calcium chloride solution with a mass concentration of 2%, and let it stand for 2h at room temperature;

S3: Rinse three times quickly with distilled water, slowly add it dropwise to the calcium chloride solution at a distance of 10cm above the liquid level of the calcium chloride solution, let stand for 2 hours at room temperature, rinse three times quickly with distilled water, and dry the surface with filter paper water to obtain a potato slow-release sprout inhibitor.

The application of the sprouting inhibitor prepared by the above-mentioned method in suppressing the sprouting of potatoes that have passed the dormant period is also the content of the present invention.

During the storage of potatoes that have passed the dormant period, sprinkle the potato slow-release germination inhibitor on the surface of the potato, and cover the potato packing box or potato pile.

In the present invention, the polysaccharide material was tested for embedding methyl salicylate, and it was found that the entrapment rate of fucoidan was better than other polysaccharide materials. The utilization value of polysaccharides can improve the stability of methyl salicylate and slow down the release rate to meet the needs of potato storage and logistics.

The slow-release sprouting inhibitor prepared in the present invention has the advantages of non-toxic and harmless raw materials, low cost, and simple preparation process steps, which solves the problem that methyl salicylate is easily oxidized, has a fast release speed, and has poor efficacy. It is a lasting problem. It has a significant effect on inhibiting the budding of potato tubers that have passed the dormant period, and has strong practicability.

Description of drawings

Figure 1 shows the effects of fucoidan concentration (a), calcium chloride concentration (b), Tween 80 (c), and core-to-wall ratio (d) on the encapsulation rate of methyl salicylate;

Fig. 2 is a differential scanning calorimetry curve comparison diagram of fucoidan (a), blank hydrogel (b) and slow-release sprouting inhibitor (c);

Fig. 3 is the release rate comparison chart of methyl salicylate (a) and methyl salicylate hydrogel (b);

Figure 4 is a comparison chart of the sprouting inhibition effect of control (CK), methyl salicylate (MeSA) and methyl salicylate hydrogel (MeSA hydrogel);

Figure 5 is a graph of germination rate (a) and germination index (b) of control (CK), methyl salicylate (MeSA), and methyl salicylate hydrogel (MeSA hydrogel) treatments.

Detailed ways

In order to enable those skilled in the art to better understand the present invention, the present invention will now be further described in detail with reference to the specific embodiments. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

Example 1

1.1 Investigate the embedding rate of different polysaccharide embedding agents

Due to the good biocompatibility and degradability of polysaccharide hydrogels, the present invention selects cellulose, sodium alginate, chitosan, xanthan gum, hyaluronic acid, konjac glucomannose, pectin, fucoid Polysaccharide Eight kinds of polysaccharide hydrogel materials were used as slow-release carriers for screening test of embedding agent. The results are shown in Table 1:

Table 1 Encapsulation rate of polysaccharide embedding agent

It can be seen from Table 1 that the same is polysaccharide, but the embedding rate of fucoidan is significantly higher than other embedding agents, the embedding rate is 76.32%. In addition, the embedding rate of sodium alginate and cellulose is also higher than that of other embedding agents. Therefore, fucoidan, sodium alginate and cellulose were selected as the most preferred embedding agents for the embedding of methyl salicylate. However, the possibility that sodium alginate and cellulose can be used as embedding materials cannot be denied, and the embedding rates of sodium alginate and cellulose are also relatively high, so the inventors have continued to conduct other experiments.

1.2 Investigate the preparation method of hydrogel

Step-by-step heating and stirring method: S1: Take 0.35g of fucoidan and put it in 20mL of distilled water, heat it to 80℃ in a magnetic stirrer to dissolve, add 30μL of Tween and 0.7mL of methyl salicylate respectively, and heat to 60℃ High-speed stirring for 15min to prepare a uniform emulsion; the speed of high-speed stirring is 2000rpm;

S2: suck the above emulsion into a 1mL syringe, slowly add it dropwise to the calcium chloride solution, and let it stand for 2h at room temperature;

S3: Quickly rinse with distilled water for 3 times, and dry the surface moisture with filter paper to obtain a potato slow-release germination inhibitor.

The ultrasonic-microwave combined method is the preferred preparation method in the present invention, and the specific steps are shown in the method in Example 2.

Table 2 Comparison table of step-by-step heating and stirring method and ultrasonic-microwave combined method

Emulsion preparation method Features time/min temperature/℃ Methyl salicylate loss rate/% Step-by-step heating and stirring method Three steps to make a homogeneous emulsion 50 60, 80 17 Ultrasonic-Microwave Combined Method One-step uniform emulsion 1.5～3 25 1.5

It can be seen from Table 2 that both the step-by-step heating and stirring method or the ultrasonic-microwave combined method can achieve the purpose of preparing hydrogels, but the two methods have different characteristics: the step-by-step heating and stirring method takes a long time, and the temperature High, the loss rate of methyl salicylate is higher than the ultrasonic-microwave combined method; the ultrasonic-microwave combined method takes a relatively short time, the preparation process can be carried out at room temperature, and the loss rate of methyl salicylate is low.

Example 2

(1) Preparation method of slow-release potato sprout inhibitor

Taking fucoidan as an example, the effect of the hydrogel prepared with methyl salicylate on inhibiting potato germination was analyzed. The specific preparation method is as follows:

Take 0.35g of fucoidan and put it in 20mL of distilled water, add 30μL of tween and 0.7mL of methyl salicylate in turn, and at room temperature, use the ultrasonic-microwave combined method to promote dissolution, ultrasonic power 400W, microwave power 900W, treatment time 2min, Forms a homogeneous white emulsion.

Suction the above white emulsion into a 1mL syringe, slowly add it dropwise to a calcium chloride solution with a mass concentration of 2%, let it stand for 2h at room temperature, rinse it three times with distilled water, and use a liquid 10cm higher than the calcium chloride solution level. It was slowly added dropwise to the calcium chloride solution, allowed to stand at room temperature for 2 hours, quickly rinsed with distilled water for 3 times, and the surface water was blotted with filter paper to obtain a potato slow-release germination inhibitor.

The dosages of fucoidan, Tween and methyl salicylate are shown in the single factor experiment in (2).

(2) Single factor test

Take fucoidan concentration (0.5, 1.0, 1.75, 2.5, 3.25%), calcium chloride mass concentration (1.0, 1.5, 2.0, 2.5, 3.0%), Tween concentration (0.1, 0.15, 0.2, 0.25, 0.3%) ), the ratio of methyl salicylate to the carrier fucoidan (0.5:1, 1:1, 2:1, 3:1, 4:1) was a single factor test to investigate the effect of one factor on the hydrogel. In the case of embedding rate, other factors were the mass concentration of fucoidan (1.0%), the mass concentration of calcium chloride (1.25%), the concentration of Tween (0.2%), and the ratio of core to wall (2:1).

The single factor results are as follows:

Table 3 Embedding rate under single factor test

(3) Determination of Embedding Rate

Weigh 0.2 g of the hydrogel, add 10 mL of 95% absolute ethanol, grind until completely broken, and sonicate for 20 min to completely dissolve the wall. Then centrifuge at 12000r for 10min, take the supernatant and dilute the volume to a 50mL volumetric flask, take a certain amount of the solution and dilute it to an appropriate multiple, measure its absorbance at the maximum absorption wavelength (309nm), and according to the standard curve (y= 24.674x-0.0649, R ² =0.9969) to calculate the methyl salicylate content in the hydrogel.

Analysis of the results: As shown in Figure 1, when the concentration of fucoidan increased from 0.5% to 3.25%, the encapsulation first increased and then decreased. When the fucoidan concentration was 1.75%, the encapsulation rate reached 77.12%. High concentrations of fucoidan increased the viscosity of the solution, resulting in a stringy gel that exhibited a tadpole-like appearance, resulting in lower encapsulation efficiency.

The entrapment rate increased with the increase of CaCl ₂ concentration and reached a maximum when the CaCl ₂ concentration was 2.0%. When the _CaCl2 concentration increased above 2.0%, the entrapment rate gradually decreased. The Ca ²⁺ concentration affects the structure of the microspheres. When the Ca ²⁺ concentration decreases, the formed microspheres have a looser structure and cannot wrap the essential oil well, resulting in a lower entrapment rate. As the concentration of _CaCl2 increases, the pores in the formed gel become smaller and the space for embedding essential oils is limited, resulting in a decrease in the encapsulation efficiency.

When the concentration of Tween 80 was 0.2%, the entrapment rate was the highest. Due to the interaction between the emulsifier and the oil molecules, the interfacial tension changes, the oil enters the water phase to form a stable emulsion, and the methyl salicylate is embedded under the action of the ionic cross-linking agent. When the core-to-wall ratio was 2:1, the entrapment rate reached the maximum value (78.24%), and then showed a downward trend. The reason for this may be that the amount of essential oil added is too high to fully emulsify, resulting in an uneven emulsion.

Example 3

Stability test: The thermograms of fucoidan, methyl salicylate and slow-release sprouting inhibitor were collected by differential scanning calorimeter. Accurately weigh the sample into an aluminum crucible and put it into the sample tank for detection. The temperature range is 20-200 °C, and the heating rate is 10 °C/min.

Analysis of results: As shown in Figure 2, fucoidan has a strong and narrow absorption peak at 141.92 °C, while the blank gel (without methyl salicylate) and methyl salicylate gel have peaks at 148.73 °C and 171.79 °C, respectively. Broad and weak absorption peaks, which indicate continuous evaporation of water molecules within the gel matrix with increasing temperature. Compared with the empty gel, the methyl salicylate gel has a higher temperature corresponding to the absorption peak, which indicates that the fucoidan encapsulates the methyl salicylate and improves the stability of the gel.

Example 4

Sustained-release performance experiment: 1 g of methyl salicylate hydrogel was randomly selected every day and placed in a mixture of 2 mL of distilled water and 5 mL of ethanol for 24 hours. The same treatment method was used for methyl salicylate. After soaking for 24 hours, the content of methyl salicylate in the supernatant was measured with a UV-Vis spectrophotometer at a wavelength of 309 nm.

Analysis of the results: As shown in Figure 3, methyl salicylate was rapidly released on the first day of storage, while the methyl salicylate hydrogel exhibited a slow release state during the entire storage process. Within one week of monitoring, the methyl salicylate hydrogel could be released continuously, and after the 4th day, the methyl salicylate was almost completely volatilized. This shows that the hydrogel beads not only have a high entrapment rate, but also release slowly and steadily after entrapment, so as to achieve the purpose of continuous drug delivery.

Example 5

Bud-inhibiting effect test: Screen the potato tubers that have passed the dormant period, remove the potatoes with mechanical damage and pests and diseases, and then divide the potatoes into 10L plastic baskets, each group of 3 baskets, each basket weighs 2kg. 3 g of slow-release germination inhibitor was weighed and placed in a petri dish, surrounded by potatoes, sealed in a plastic basket, and then fumigated at 25°C.

Of course, in actual use, the potato slow-release germination inhibitor can also be sprinkled on the surface of the potato, and covered with a cloth in the potato packing box or in the potato pile. The weight ratio of the potato to the germination inhibitor is 1000:1.5-3.

The potato sprout inhibitor is prepared by the following method:

Take 0.2g of fucoidan and put it in 40mL of distilled water, add 40μL of tween and 0.4mL of methyl salicylate in turn, and at room temperature, use the ultrasonic-microwave combined method to promote dissolution, ultrasonic power 400W, microwave power 900W, treatment time 2min, Forms a homogeneous white emulsion.

Suction the above white emulsion into a 1mL syringe, slowly add it dropwise to a calcium chloride solution with a mass concentration of 2%, let it stand for 2h at room temperature, rinse it three times with distilled water, and use a liquid 10cm higher than the calcium chloride solution level. It was slowly added dropwise to the calcium chloride solution, allowed to stand at room temperature for 2 hours, quickly rinsed with distilled water for 3 times, and the surface water was blotted with filter paper to obtain a potato slow-release germination inhibitor.

In table 4, other polysaccharides (sodium alginate, cellulose, hyaluronic acid) and methyl salicylate prepare the same method for hydrogel;

Analysis of the results: As shown in Figure 4, when stored for 18 days, the control group had obvious germination, and the buds grew longer. The methyl salicylate direct fumigation group germinated more, second only to the control group, and the methyl salicylate hydrogel Potato tubers in the treatment group sprouted less and only had fine buds. As shown in Figure 5, at the end of storage (18d), the germination rate and germination index of the control group were 100% and 28.57%, respectively. The methyl salicylate hydrogel treatment group had the best germination inhibition effect, and the germination rate and germination index were only were 3.33% and 0.67%.

Table 4 Comparison of application effects of hydrogels under different experimental examples in potato germination inhibition

group Polysaccharide + Methyl Salicylate Germination rate% Germination Index % control group blank 100 28.57 Experimental example 1 0.1g fucoidan + 0.4mL methyl salicylate 21.00 8.77 Experimental example 2 0.2g fucoidan + 0.4mL methyl salicylate 3.33 0.67 Experimental example 3 0.4g Fucoidan + 0.4mL Methyl Salicylate 16.67 5.87 Experimental example 4 0.2g cellulose + 0.4mL methyl salicylate 25.00 12.35 Experimental example 5 0.2g sodium alginate + 0.4mL methyl salicylate 19.25 7.27 Experimental example 6 0.2g hyaluronic acid + 0.4mL methyl salicylate 28.00 14.57

It can be seen from the data in the above table that when the ratio of fucoidan: methyl salicylate increases from 1:4 to 1:1, the bud-inhibiting effect does not increase linearly, where 1:2 (0.2 g Algal polysaccharide: 0.4mL methyl salicylate) is the best, 1:1 may be because the cross-linking degree of fucoidan is too high, resulting in slow release of methyl salicylate; 1:4 may fail to compare Good encapsulation of methyl salicylate will release too fast, resulting in a decrease in the bud-inhibiting efficiency.

The compound test of cellulose, hyaluronic acid, sodium alginate and methyl salicylate (0.4mL) was carried out in the ratio of 1:2. %, 28% and 19.25%, the germination index was 12.35%, 14.57% and 7.27% respectively, but they were not as good as the compounding effect of fucoidan and methyl salicylate, the germination rate was 3.33%, and the germination index was 0.67% .

Claims (10)

1. The application of the slow-release sprout inhibitor in inhibiting the sprouting of potatoes is characterized in that the sprout inhibitor is prepared by taking fucoidin and methyl salicylate as raw materials.

2. The use of claim 1, wherein the weight to volume ratio of fucoidan to methyl salicylate is 1 g: 2 mL.

3. The slow-release bud inhibitor is characterized in that the bud inhibitor is prepared by taking fucoidin as a slow-release carrier and methyl salicylate as an active bud inhibiting component as raw materials.

4. The slow-release sprout inhibitor of claim 3, wherein the weight-to-volume ratio of fucoidan to methyl salicylate is 1 g: 2 mL.

5. The slow-release sprout inhibitor of claim 3, wherein the slow-release sprout inhibitor is prepared by dissolving fucoidin, adding methyl salicylate and emulsifier to prepare emulsion, and adding calcium chloride to prepare the slow-release sprout inhibitor.

6. A method for preparing a sustained-release sprout inhibitor according to claim 3, comprising the steps of:

s1: adding fucoidin into distilled water, heating and stirring in a magnetic stirrer for 15min to dissolve, adding Tween and methyl salicylate, respectively, heating and stirring at high speed for 15min to obtain emulsion;

s2: sucking the emulsion in the S1 into a syringe, slowly adding the emulsion into a calcium chloride solution drop by drop, and standing at room temperature;

s3: quickly washing with distilled water, and drying with filter paper to obtain the slow-release potato sprout inhibitor.

7. A process for preparing a sustained-release sprout inhibitor according to claim 6, comprising the steps of:

s1: placing 0.35g fucoidin in 20mL distilled water, heating to 80 deg.C in a magnetic stirrer for dissolving, adding 30 μ L tween and 0.7mL methyl salicylate, heating to 60 deg.C, stirring at high speed for 15min, and making into uniform emulsion;

s2: sucking the emulsion into a 1mL syringe, dropwise and slowly adding the emulsion into a calcium chloride solution, and standing for 2 hours at room temperature;

s3: quickly washing with distilled water for 3 times, and drying with filter paper to obtain the slow-release potato sprout inhibitor.

8. A process for preparing a sustained-release sprout inhibitor according to claim 6, comprising the steps of:

s1: placing 0.2g of fucoidin in 40mL of distilled water, sequentially adding 40 mu L of spit temperature and 0.4mL of methyl salicylate, promoting dissolution by adopting an ultrasonic-microwave combination method at normal temperature, wherein the ultrasonic power is 400W, the microwave power is 900W, and the treatment time is 2min to form uniform white emulsion;

s2: sucking the white emulsion into a 1mL syringe, dropwise and slowly adding the white emulsion into a calcium chloride solution with the mass concentration of 2%, and standing for 2 hours at room temperature;

s3: quickly washing with distilled water for 3 times, slowly adding into calcium chloride solution dropwise at a distance of 10cm higher than the liquid level of the calcium chloride solution, standing at room temperature for 2h, quickly washing with distilled water for 3 times, and drying with filter paper to obtain the potato slow-release sprout inhibitor.

9. Use of a slow-release sprout inhibitor prepared by the method of any one of claims 6 to 8 for sprout inhibition of potatoes which have passed through dormancy.

10. Use of a slow-release sprout inhibitor prepared by the process of claim 9 for sprout inhibition of potatoes which have passed through dormancy, characterized in that, when the potatoes which have passed through dormancy are stored, the slow-release sprout inhibitor is scattered on the surface of the potatoes and covered with a cloth in a potato packaging box or a potato stack, the weight ratio of the potatoes to the sprout inhibitor being 1000: 1.5 to 3.

Images