Peppermint essential oil emulsion for preventing and treating ham pests and preparation method of peppermint essential oil emulsion

Abstract

The invention provides application of peppermint essential oil in prevention and treatment of ham pests and a preparation scheme of peppermint essential oil emulsion, and belongs to the technical field of ham pest prevention and treatment. New application of the peppermint essential oil in the aspect of ham pest control is found for the first time, the peppermint essential oil emulsion is prepared from the peppermint essential oil, chitosan, acetic acid, glycerin, Tween 80 and water, the safety of the obtained emulsion is far higher than that of a traditional chemical insecticide method, and the method is low in cost, easy and convenient to prepare, remarkable in effect and suitable for industrial production. Good effects are shown in egg laying repelling of adult casein flies, pupation inhibition of third-instar larvae, eclosion inhibition of pupae, contact toxicity of second-instar larvae and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of ham pest control, and particularly relates to a peppermint essential oil emulsion for controlling ham pests and a preparation method thereof. Background Art

[0002] Dry-cured ham is a traditional Chinese delicacy, which is loved by the public for its non-greasy, salty and fragrant taste, unique flavor, and green and healthy characteristics. However, the traditional dry-cured ham production process is susceptible to the invasion of various pests such as case flies and putrescent tyrophagous mites, posing a serious threat to the quality and sanitary safety of dry-cured ham. Pests not only eat deep into the ham, causing the ham to rot, deteriorate, and turn black, but may also carry harmful bacteria such as Providencia rettgeri, increasing food safety risks. Therefore, solving the problem of ham pests is not only crucial to the economic benefits of the enterprise, but also related to the health and safety of consumers, and effective prevention and control measures are urgently needed.

[0003] At present, the pest control technology of dry-cured ham mainly includes two methods: spatial isolation and chemical pesticides, but they each have great limitations. The spatial isolation method has a wide range of applications, and uses a 600-1200 mesh screen to block the case fly from laying eggs in the ham. However, too dense a mesh may affect the evaporation of ham water, extend the production cycle, and the control effect on putrescent tyrophagous mites is not ideal. On the other hand, although chemical pesticides have a certain control effect, the toxic ingredients contained in them, such as amyl alcohol and n-amyl formate, still pose many food safety risks.

[0004] Therefore, it is urgent to develop greener and safer prevention and control technologies to ensure the quality of ham and the health of consumers. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a peppermint essential oil emulsion for controlling ham pests and a preparation method thereof. The present invention discovers for the first time a new use of peppermint essential oil in controlling ham pests, and the prepared peppermint essential oil emulsion is much safer than the traditional chemical pesticide method. The method is low in cost, simple to prepare, and has significant effects, and shows good effects in egg-laying repellence of case fly adults, pupation inhibition of 3rd instar larvae, emergence inhibition of pupae, and contact toxicity of 2nd instar larvae.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides the use of peppermint essential oil in controlling ham pests.

[0008] In a second aspect, the present invention provides a peppermint essential oil emulsion for controlling ham pests, characterized in that it comprises the following components in parts by weight:

[0009] The invention comprises 1-10% peppermint essential oil, 1-3% chitosan, 1-3% cosolvent aqueous solution, 0.5-1.5% plasticizer, 0.5-1.5% emulsifier and the balance is water.

[0010] By adopting the above scheme, the strong flavor and high volatility of peppermint essential oil, and the problem that directly using it in food may affect the flavor and taste of food are solved. The use of chitosan (CS)-based essential oil emulsion coating significantly reduces the impact on the flavor and taste of ham, and increases the action time of peppermint essential oil.

[0011] Preferably, the aqueous solution of the co-solvent comprises one or more of acetic acid, lactic acid, citric acid, malic acid, ascorbic acid, acetic acid, tartaric acid and phosphoric acid.

[0012] Preferably, the plasticizer includes one or more of glycerol, tributyl citrate, acetyl tributyl citrate, epoxidized soybean oil, sorbitan fatty acid ester, epoxidized linseed oil, and polyethylene glycol.

[0013] Preferably, the emulsifier includes one or more of Tween, calcium carbonate, span, fatty acid salts, sulfate esters, gelatin, and gum arabic.

[0014] Preferably, the peppermint essential oil is an essential oil extracted from the aerial part of peppermint using a steam distillation method.

[0015] Preferably, the main active ingredients of the peppermint essential oil include menthol, limonene, menthone, sabinene, β-pinene and eucalyptol.

[0016] Preferably, the peppermint essential oil emulsion further comprises a pharmaceutically acceptable excipient.

[0017] Preferably, pharmaceutically acceptable excipients include: solubilizers, aqueous solutions of cosolvents, emulsifiers, colorants, adhesives, disintegrants, fillers, lubricants, wetting agents, osmotic pressure regulators, stabilizers, glidants, flavoring agents, preservatives, suspending agents, coating materials, fragrances, anti-adhesives, integrators, penetration enhancers, pH regulators, buffers, plasticizers, surfactants, foaming agents, defoamers, thickeners, inclusion agents, humectants, absorbents, diluents, flocculants, deflocculating agents, filter aids, and release retardants.

[0018] Preferably, the peppermint essential oil emulsion can be made into powder or spray.

[0019] In a third aspect, the present invention provides a method for preparing the above-mentioned peppermint essential oil emulsion for controlling ham pests, comprising the following steps:

[0020] 1) Weighing each raw material according to the weight portion;

[0021] 2) dissolving chitosan in the aqueous solution of the co-solvent and mixing them uniformly to obtain a solution A;

[0022] 3) uniformly mixing solution A and plasticizer to obtain solution B;

[0023] 4) Evenly mixing solution B, peppermint essential oil and emulsifier to obtain a peppermint essential oil emulsion for controlling ham pests.

[0024] Preferably, in step 2), the mixing temperature is 20-30° C. and the mixing time is 2-6 h.

[0025] Preferably, in step 3), the mixing temperature is 20-30° C. and the mixing time is 1-3 h.

[0026] In a fourth aspect, the present invention provides an application of the above-mentioned peppermint essential oil emulsion in controlling ham pests, wherein the ham pests controlled include case flies, putrescent tyrophagous mites, and red-necked coconut beetles.

[0027] Preferably, the control methods include repelling, suppressing, contact killing or fumigating.

[0028] Preferably, the pest control stages include egg, larva, pupa and adult stages.

[0029] Contains at least the following beneficial technical effects:

[0030] 1) The present invention is the first to discover a new use of peppermint essential oil in ham pest control. This use is mainly achieved through the repellent, inhibitory and lethal effects of peppermint essential oil on different insect stages of pests.

[0031] 2) The present invention reduces the influence on the flavor and color of ham by mixing chitosan with peppermint essential oil and emulsifying it.

[0032] 3) The mint essential oil emulsion of the present invention is much safer than the traditional chemical insecticide method. The method is low-cost, simple to prepare, and has significant effects. It shows good effects in egg-laying repelling of case fly adults, pupation inhibition of 3rd instar larvae, pupal emergence inhibition, and contact toxicity of 2nd instar larvae. It provides ideas for the application of mint essential oil in pest control of dry-cured ham. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the particle size distribution diagram of peppermint essential oil emulsions with different concentrations;

[0034] Figure 2 Electronic tongue sensory score graph of adding different concentrations of essential oil emulsions to dry-cured ham;

[0035] Figure 3 This is a picture of the color difference between the ham treatment groups with different essential oil emulsions;

[0036] Figure 4 Figure 1. Repellent effect of adding essential oil emulsion to dry-cured ham on case fly larvae;

[0037] Figure 5 This is a graph showing the local contact toxicity effect of peppermint essential oil emulsion on the second-instar larvae of case flies;

[0038] Figure 6 This is a graph showing the toxic effect of peppermint essential oil emulsion on the pupation inhibition of the third instar larvae of case flies after topical contact;

[0039] Figure 7 This is a diagram showing the toxic effect of peppermint essential oil emulsion on the emergence inhibition of case fly pupae;

[0040] Figure 8 This is a statistical chart of the number of eggs laid by casei adults after the ham was covered with essential oil emulsions of different concentrations;

[0041] Fig. 9 This is a comparison chart of the egg-laying situation of adult case flies on the surface of ham. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The term "include" or "comprising" in the present invention is an open description containing the specified components or steps described, and other specified components or steps that will not be substantially affected.

[0044] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0045] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0046] The peppermint essential oil used in the present invention can be selected from any part of peppermint or any part of its plant or extracted.

[0047] The peppermint essential oil used in the following examples is sourced from Ji'an Guoguang Spice Factory.

[0048] Example 1

[0049] Analysis of essential oil chemical composition: The chemical composition of essential oils was analyzed using a standardized extraction process (Caballero-Gallardo et al., 2011). First, 5 g of essential oil sample was placed in a 20 mL headspace bottle and equilibrated at room temperature (25 ± 2 °C) for 30 min. Then, a 50 / 30-μm DVB / Carboxen / PDMS extraction fiber was used and gently shaken at 50 °C for 30 min to adsorb volatile components using the SPME technique. Gas chromatography (GC) analysis was performed using a gas chromatograph equipped with a triple quadrupole mass spectrometer. During the analysis, a non-polar HP-5MS column (30 m × 0.25 mm × 0.25 μm) and a polar HP-Innowax column (30 m × 0.25 mm × 0.25 μm) were used for chromatographic separation. The chromatographic conditions were set as follows: initial temperature 50°C for 10 min, then raised to 150°C at a rate of 5°C / min and held for 3 min, then raised to 240°C at a rate of 5°C / min and held for 3 min. Mass spectrometry (MS) used electron impact ionization (EI+), ionization energy 70 eV, ion source temperature 250°C, transfer line temperature 240°C, and mass analysis range 35-550 amu. GC-MS data combined with retention index, compound identification was performed using the NIST17 and Wiley9 databases, and the main active ingredients are shown in Table 1.

[0050] Table 1

[0051]

[0052] Example 2

[0053] 1. Repellent effect of peppermint essential oil on case fly larvae

[0054] The repellent effect of peppermint essential oil on case fly larvae The case fly larvae repellent experiment in this study was based on the method of Kumar et al., (2014) and was designed to explore the effect of essential oil on the antifeeding behavior of case fly larvae. The experiment used a Petri dish (Φ90 mm) and divided it into two parts. Broth was added to the control group, and different concentrations of essential oil broth mixture (10%, 50%, 100%) were added to the test group. In order to prevent the broth from volatile water vapor affecting the experimental results, a hole was manually opened on the top of the culture dish. 1.0±0.1g of 10mm×10mm×5mm fat and lean ham slices were placed in each of the two parts. At the beginning of the experiment, 20 case fly larvae were placed at the junction of the control group and the test group, and the larval tendency behavior was observed and recorded. Recording was performed every 12 hours and the observation was continued for 48 hours. The repellency rate was calculated as shown in formula (1):

[0055]

[0056] Where Cn is the number of case flies appearing in the untreated (control) part, and Tn is the number of case flies appearing in the treated part.

[0057] According to statistics, the repellent effect of 50% concentration of peppermint essential oil on case fly larvae reached 66% in 24 hours and 75% in 48 hours; the repellent rate of 100% concentration of peppermint essential oil was 72% in 24 hours and 82% in 48 hours.

[0058] 2. Topical contact toxicity of peppermint essential oil to the second-instar larvae of case fly

[0059] Based on the fact that the second-instar larvae of case flies cannot jump and pupate compared to the third-instar larvae, this study refers to and optimizes the local contact toxicity test method of Kumar et al. (2013) to evaluate the effects of three essential oils on young case fly larvae. The experiment was conducted in a Petri dish (Φ90 mm). First, the essential oil was diluted with anhydrous ethanol and evenly dispersed on filter paper (0.5-5 μL / cm 2 ), the total volume was controlled at 636 μL / sheet. The control group was treated with anhydrous ethanol only. After treatment, the filter paper was air-dried at 25°C in a fume hood for 5 minutes to accelerate the evaporation of the solvent. Subsequently, 10 second-instar larvae were placed in each culture dish, and 10mm×10mm×5mm fat-lean ham slices weighing 1.0±0.1g were added. After the experiment lasted for 48 hours, the survival data of the larvae were recorded, and each group was repeated 5 times. If the second-instar larvae of the case fly did not respond after 48 hours or did not move under strong light, they were judged to be dead.

[0060] According to statistics, the 48h contact toxicity LC value of peppermint essential oil to the second instar larvae of case flies is 30 2.944 μL / cm 2 , L.C. 50 3.66μL / cm 2 , L.C. 90 6.231 μL / cm 2 .

[0061] 3. Topical contact pupation inhibition toxicity of peppermint essential oil on the third instar larvae of case fly

[0062] In view of the fact that the third-instar larvae of case flies have the ability to pupate, this study improved the local contact toxicity test method of Kumar et al. (2013) to evaluate the local contact inhibitory effect of essential oils on the third-instar larvae of case flies. The experiment was carried out in a Petri dish (Φ90 mm). First, the essential oil was diluted with anhydrous ethanol and evenly dispersed on filter paper (0.5-10 μL / cm 2), the total volume was controlled at 636 μL / sheet. The control group was treated with anhydrous ethanol only. After treatment, the filter paper was air-dried at 25°C in a fume hood for 5 min to accelerate the evaporation of the solvent. Subsequently, 10 third-instar larvae of case flies were added to each culture dish without adding food. The larval pupation data were recorded after 5 days of observation, and each concentration group was repeated 5 times. If the third-instar larvae of case flies did not respond to touch and strong light exposure within 24 hours, and failed to pupate successfully after 5 days, the third-instar larvae were judged to be dead, indicating that the pupation process was inhibited.

[0063] According to statistics, the IC value of peppermint essential oil on the 5-day pupation inhibition of the third-instar larvae of case flies is 30 3.59 μL / cm 2 ,IC 50 4.986 μL / cm 2 ,IC 90 11.127 μL / cm 2 .

[0064] 4. Local contact inhibition toxicity of peppermint essential oil on emergence of case fly pupae

[0065] This study optimized the local contact toxicity test method for pests, aiming to explore the local contact inhibitory effect of essential oils on case fly pupae (Gong Qingtao et al., 2021). The experiment was carried out in a Petri dish (Φ90mm). First, the essential oil was diluted with anhydrous ethanol and evenly dispersed on filter paper (0.5-10μL / cm 2 ), the total volume was controlled at 636 μL / sheet. The control group was treated with only anhydrous ethanol. The treated filter paper was air-dried in a fume hood at 25°C for 5 min to accelerate the evaporation of the solvent. Subsequently, 10 case fly pupae were added to each culture dish without adding food. The larval pupation data were recorded for 30 days, and each concentration group was repeated 5 times. If the case fly pupa did not change color within 48 hours and still failed to successfully emerge after 30 days, it was judged to be dead, indicating that the pupal emergence was inhibited.

[0066] According to statistics, the inhibitory effect of peppermint essential oil on the emergence of case fly pupae is 1 μL / cm 2 Under the condition of 96%, at 3μL / cm 2 A 100% feathering inhibition effect can be achieved.

[0067] 5. Repellent effect of peppermint essential oil on adult case flies

[0068] This study used a repellent device to evaluate the repellent effect of essential oils on adult case flies (Tian Hui, 2023). A 2cm×2cm filter paper was adsorbed with essential oil and placed at the bottom of the device, and an air pump was set to generate an appropriate flow rate to ensure air circulation in the device. Broth was added to part of the control group, and a mixture of essential oil and broth of different concentrations was added to part of the test group. Subsequently, an adult case fly was placed in a Y-shaped tube, and its bias was recorded after observation for 1 minute. Five parallel replicates were set for each group of experiments to ensure the reliability of the results.

[0069] According to statistics, the repellent effect of peppermint essential oil on case fly adults is 1 μL / cm 2 Under the condition of 43%, while 2μL / cm 2 A repellent effect of 83% can be achieved.

[0070] 6. Fumigation toxicity of peppermint essential oil to adult case flies

[0071] This study used a modified triangular flask fumigation method, referring to the method of Chen Wei et al. (2018), to evaluate the fumigation toxicity of essential oils to adult case flies. The experiment used a sealed glass conical bottle with a nominal volume of 250 mL, and the actual effective gas volume was 300 mL. Essential oil (0.5, 0.1 mL / L of air) was dripped onto a filter paper sheet (4 cm×4 cm) and placed under the bottle stopper. The control group used only deionized water. Ten adult case flies were placed in each conical bottle, and 1.0±0.1 g of fat and lean ham was provided as food. The experiment was repeated 4 times at each concentration, and the death data of case fly adults were recorded at 1, 2, 6, 12, 24 and 48 h. If the case fly adults were unable to fly and had no signs of limb activity, they were judged to be dead.

[0072] According to statistics, the fumigation effect of peppermint essential oil on adult case flies is 0.5 μL / cm 2 Conditions LT 50 reached 7.061h (0.212-16.052h), while 1μL / cm 2 Conditions LT 50 It can reach 0.872h (0.12-2.296h), and has a very strong fumigation effect.

[0073] Example 2

[0074] 1. Preparation of peppermint essential oil emulsion for controlling ham pests:

[0075] Chitosan was dissolved in a 1% (v / v) acetic acid aqueous solution (prepared from acetic acid and water) and mixed at 25°C for 4 h to obtain solution A;

[0076] Solution A was mixed with glycerol at 25°C for 1 h to obtain solution B;

[0077] The solution B, peppermint essential oil and Tween 80 were evenly mixed to obtain a peppermint essential oil emulsion for controlling ham pests.

[0078] The proportions of each component are shown in Table 2.

[0079] Table 2

[0080]

[0081] 2. Preparation and Particle Size Characterization of Peppermint Essential Oil Emulsion

[0082] After sampling the prepared emulsion, it was diluted 10 times with deionized water, and the nanoparticle size and dispersion index were measured using a wide dynamic potential and nanoparticle size analyzer (Wang Qiuping et al., 2022).

[0083] The particle size distribution of peppermint essential oil emulsion is as follows Figure 1 As shown. Overall, with the increase of mint EO concentration, the average particle size and dispersion index of the emulsion both show an upward trend (Ding Hongying et al., 2024). In the lower EO concentration of 1% EO+CS, the average particle size of the emulsion is 221.5nm (PDI=0.307), and at 5% EO+CS concentration, the average particle size of the emulsion rises to 422nm (PDI=0.322). With the further increase of concentration, the average particle size of the emulsion with a concentration of 10% EO+CS is 937.7nm (PDI=0.352), but the relative volume of the particle size is more concentrated, indicating a more uniform distribution.

[0084] 3. Effect of essential oil emulsion on the taste of ham

[0085] 10.0±0.1g of air-dried ham was placed in the essential oil emulsion for 5 minutes to cover the surface of the ham with the essential oil emulsion (about 200μL / g). After air-drying at 25℃ in a fume hood for 5 minutes, it was placed in an incubator for fermentation for 5 days. The incubator conditions were set at a temperature of 25±1℃ and a relative humidity of 70±5%. After 5 days, 5.0±0.1g of sample was weighed and mixed with 40mL of distilled water (37℃), and homogenized at 3000rpm for 60s using a high-speed homogenizer. Then centrifuged at 2000g for 10 minutes at 4℃, and the supernatant was filtered. 10mL of the filtrate was mixed with 50mL of ultrapure water. The taste value was evaluated using the SA402B electronic tongue two-step cleaning method, and the reference solution was a mixed solution of 0.3mM tartaric acid and 30mM potassium chloride (Liu et al., 2022).

[0086] The multifunctional taste perception system (electronic tongue) can simulate human taste perception and distinguish different taste signals in a short time. Figure 2The electronic tongue sensory scores of the taste sensing system for dry-cured ham with the addition of different concentrations of essential oil emulsions were shown, including sourness, bitterness, astringency, richness, saltiness, umami, afterbitterness and afterastringency (Liu Linggao, 2023). The results showed that except for the 100% EO+CS group, the sensory scores between other different treatment groups were relatively small. This shows that the appropriate addition of essential oil emulsions during the fermentation process of dry-cured ham will not significantly affect the taste and flavor of the ham. However, the acidity, richness and afterastringency scores of the 100% EO+CS group were significantly reduced, which may mean that the addition of high concentrations of pure essential oils has a greater impact on the flavor of the ham and changes its original taste and flavor. In the following, we will focus on the effect of essential oil emulsions on insect prevention in dry-cured ham.

[0087] 4. Effect of essential oil emulsion on ham color

[0088] 5.0±0.1g of air-dried ham was placed in the essential oil emulsion for 5 minutes, and the surface of the ham was covered with the essential oil emulsion (about 200μL / g). Air-dried in a fume hood at 25℃ for 5 minutes, and fermented in an incubator for 5 days. The incubator conditions were set at a temperature of 25±1℃ and a relative humidity of 70±5%. A colorimeter was used for color detection. Each group was repeated 3 times (Zhang et al., 2024).

[0089] The effect of peppermint essential oil emulsion on the surface color of ham is shown in Table 3 and Figure 3 As shown. By comparison, it was found that there was no significant difference in the L* (brightness or brightness) value between the control group C and 10% EO+CS, which shows that at a concentration of 10% peppermint essential oil, the emulsion has little effect on the brightness of the ham and can maintain the original color of the ham. The L values ​​of the other groups with the addition of emulsions all had certain differences, which significantly improved the brightness of the ham. The overall positive value of a* (redness value) shows that the color of all sample meats tends to be red, and there is no significant difference between all other groups except the 1% EO+CS group, indicating that the effects of different concentrations of essential oil emulsions on the redness value of meat are relatively consistent. In terms of b* value (yellowness value), all groups with added emulsions showed significant differences compared with the control group, which shows that the addition of emulsions leads to an increase in the yellowness value of the ham. This may be due to the interaction between the color of the chitosan emulsion itself and the surface of the ham. The color difference value E* is used to measure the difference between two colors. The results showed that the E* value of the 10% EO+CS group was the lowest, approximately between 2 and 3, which means that the color difference between the C group and the 10% EO+CS group is perceptible, but the difference is not significant. This shows that in practical applications, the effect of 10% peppermint essential oil emulsion on the color of ham is acceptable and will not have much impact on the appearance of ham meat (Zhang et al., 2024).

[0090] The color difference values ​​between the different essential oil emulsion treatment groups are shown in Table 3.

[0091] Table 3

[0092]

[0093] 5. Repellent effect of essential oil lotion on case fly larvae

[0094] In order to verify the repellent effect of essential oil emulsion on case fly larvae after being applied to ham, the repellent effect of essential oil emulsion on case fly larvae was studied. 5.0±0.1g ham meat was placed in the essential oil emulsion for 5 minutes, so that the surface of the ham meat was covered with essential oil emulsion (about 200μL / g). One part of the ham meat was filled with 2.0±0.1g of emulsion as the test group, and the other part was placed with ham treated with pure water as the control group. After air drying at 25℃ in a fume hood for 5 minutes, 20 case fly larvae (multiple instars) were added and placed at the junction of the control group and the test group, and the tendency of the larvae was observed, and recorded every 12 hours for 48 hours.

[0095] The repellent effect of peppermint essential oil lotion on case fly larvae Figure 4 As shown. The 5% EO+CS concentration emulsion can achieve a repellent effect of more than 50% within 12 hours, and after 36 hours, the repellent effect is stable at about 69.4%. The 10% EO+CS concentration emulsion has a repellency rate of more than 60% within 12 hours, and reaches the highest repellent effect (72.2%) at 48 hours. The repellent effect of the essential oil emulsion is somewhat lower than that of the pure essential oil. Although the repellent effect of the essential oil emulsion is lower than that of the pure essential oil, this decline may be related to the physical properties of the emulsion, such as the dispersibility and volatility of the essential oil in the emulsion may be affected by the emulsion matrix (Yang Fengshuo et al., 2024). However, the essential oil emulsion still showed a significant repellent effect, indicating that the essential oil in the form of an emulsion can still be used as an effective case fly repellent (Lucia et al., 2021).

[0096] 6. Topical contact toxicity of essential oil emulsions to second-instar larvae of case fly

[0097] 5.0±0.1g ham meat was placed in the essential oil emulsion and allowed to stand for 5 minutes, so that the surface of the ham meat was covered with the essential oil emulsion (about 200μL / g). Air-dried in a fume hood at 25°C for 5 minutes, 10 2nd instar larvae of case flies were added to the ham meat containing the emulsion, and the death data of the 2nd instar larvae were observed and recorded after 48 hours. Each concentration experiment was repeated 5 times. The judgment criteria for the death of the 2nd instar larvae of case flies were the same as those in Example 1.

[0098] Topical contact toxicity of peppermint essential oil emulsion to the second instar larvae of case fly Figure 5As shown. The experimental results show that at a concentration of 1% EO+CS, the mortality rate of the emulsion on the 2nd instar larvae of case flies has exceeded 20%, which is significantly higher than that of the C group and the CS emulsion group. This shows that the CS emulsion has no obvious insecticidal effect on the 2nd instar larvae of case flies, while the peppermint essential oil emulsion exhibits significant insecticidal activity. With the increase in the concentration of peppermint essential oil, the mortality rate of the 2nd instar larvae of case flies also increased significantly. Under the condition of 10% EO+CS, the mortality rate of the 2nd instar larvae can reach 76%, showing that the peppermint essential oil emulsion can still maintain a strong insecticidal effect. This result further confirms that peppermint essential oil emulsion can be used as an effective means of killing insects in dry-cured ham (Giunti et al., 2019).

[0099] 7. Topical contact pupation inhibition toxicity of essential oil emulsion to third-instar larvae of case fly

[0100] 5.0±0.1g of ham meat was placed in the essential oil emulsion for 5 minutes to coat the surface of the ham meat with the essential oil emulsion (about 200μL / g). The treated ham was placed in the center of a Petri dish (Φ90mm) and air-dried at 25°C in a fume hood for 5 minutes. Ten third-instar larvae of case flies were added to the ham meat containing the emulsion. After 5 days, the pupation data of the third-instar larvae were observed and recorded. The experiment was repeated 5 times for each concentration group. The criterion for judging the pupation inhibition of the third-instar larvae of case flies was the same as in Example 1.

[0101] Topical contact toxicity of peppermint essential oil emulsion on pupation inhibition of third-instar larvae of case fly Figure 6 shown.

[0102] Experimental data showed that at a concentration of 1% EO+CS, the pupation inhibition rate of the emulsion on the third-instar larvae of the case fly exceeded 30%, which was significantly higher than that of the C group and the CS emulsion group. This indicates that the CS emulsion has no obvious inhibitory effect on the pupation process of the third-instar larvae of the case fly, and the addition of peppermint essential oil significantly enhances the pupation inhibition toxicity of the emulsion (Erland et al., 2015). With the increase in the concentration of peppermint essential oil, the local contact pupation inhibition toxicity of the emulsion on the third-instar larvae is also significantly enhanced. Under the condition of 10% EO+CS, the pupation inhibition rate of the third-instar larvae can reach 60%. Although the inhibition rate of the essential oil emulsion did not reach the effect of pure peppermint essential oil, it still showed a significant inhibitory effect compared with the control group. The results further confirmed that the peppermint essential oil emulsion can be used as an effective means to control the case fly in dry-cured ham (Parichanone et al., 2023).

[0103] 8. Toxicity of essential oil emulsion to inhibit emergence of case fly pupae

[0104] 5.00±0.01g of ham meat was placed in the essential oil emulsion and allowed to stand for 5 minutes, so that the surface of the ham meat was covered with the essential oil emulsion (about 200μL / g). The treated ham was placed in the center of a Petri dish (Φ90mm), air-dried at 25°C in a fume hood for 5 minutes, and then 10 case fly pupae were added to the ham meat containing the emulsion. After 30 days, the pupation data of the third instar larvae were observed and recorded. Each concentration experiment was repeated 5 times. The judgment criteria for the inhibition of case fly pupae emergence were the same as those in Example 1.

[0105] Toxicity of peppermint essential oil emulsion to inhibit emergence of case fly pupae by topical contact Figure 7 As shown. The experimental data showed that none of the C group, CS emulsion group and 1% EO+CS group showed significant pupal emergence inhibition toxicity, indicating that the pupation inhibition effect on case fly pupae was limited when a lower concentration of peppermint essential oil was added. However, when the concentration was increased to 5% EO+CS, the emulsion significantly reduced the emergence rate of case fly pupae to less than 50%. Under the concentration condition of 10% EO+CS, the emergence rate of case fly pupae was further reduced to 8%. The results show that the emergence inhibition effect of peppermint essential oil is reduced after it is made into an emulsion. Only when a higher concentration of peppermint essential oil is present can the emulsion effectively inhibit the emergence process of case fly pupae.

[0106] 9. The oviposition-repellent effect of essential oil lotion on adult case fly

[0107] 5.0±0.1g of ham meat was placed in the essential oil emulsion for 5 minutes to cover the surface of the ham meat with the essential oil emulsion (about 200μL / g). The control group C was only soaked in water and allowed to stand. The treated ham was placed in the center of a Petri dish (Φ90mm), and 10 adult case flies (male: female = 1:1) were added to it. After sealing with plastic wrap, a 1mL sterile syringe needle was used to poke holes to ensure air circulation. After all 10 adult case flies died, the number of case fly eggs on the ham meat was observed and recorded. The experiment was repeated 3 times for each group.

[0108] Essential oil emulsion can be used as an ideal material for repelling adult ham case flies (Qualls et al., 2020). The experimental results of the repellent effect of peppermint essential oil emulsion on the egg-laying of adult case flies are as follows: Figure 8 and Fig. 9 As shown. Figure 4-5 and Figure 4-6It can be clearly seen from the photos of the number of eggs on the surface of ham that there are significant differences in the number of eggs laid by adults between groups with different essential oil concentrations. There was no significant difference in the number of eggs laid between the control group C and the CS group, which shows that in the absence of essential oils, the pure CS emulsion has no significant effect on the egg-laying behavior of the case fly adults, that is, the CS emulsion itself does not have a repellent effect. As the concentration of essential oils added increases, the repellent effect on the egg-laying of case flies adults gradually increases. In the 10% EO+CS emulsion, the egg-laying amount of case flies adults is only in the single digit, and the repellent rate is as high as 99%. Overall, even a 1% EO+CS concentration emulsion can achieve an egg-laying repellent effect of more than 50%, indicating that ham has a significant repellent effect on case fly adults after being covered with essential oil emulsion (Parichanonetal., 2023).

[0109] 10. Fumigation toxicity of essential oil emulsions to adult case flies

[0110] 5.0±0.1g ham meat was placed in the essential oil emulsion for 5min, so that the surface of the ham meat was covered with the essential oil emulsion (about 200μL / g). The treated ham meat was placed at the bottom of a calibrated volume of 250mL conical flask, where the meat was wrapped with gauze, and the actual test effective gas volume of the conical flask was 300mL. The bottle mouth was sealed with a bottle stopper, and the death data of case fly adults were recorded at 1, 2, 6, 12, 24 and 48h. Each group of experiments was repeated 4 times, and the control group used deionized water. The results are shown in Table 4.

[0111] Table 4 Fumigation toxicity of peppermint essential oil emulsion to case fly adults

[0112]

[0113] Example 3

[0114] 1. A peppermint essential oil emulsion for controlling ham pests was prepared by the method in Example 2, except that citric acid was used as the cosolvent; epoxidized soybean oil was used as the plasticizer; and span was used as the emulsifier.

[0115] 2. A peppermint essential oil emulsion for controlling ham pests was prepared by the method in Example 2, except that acetic acid was used as the cosolvent, polyethylene glycol was used as the plasticizer, and gum arabic was used as the emulsifier.

[0116] The test was also carried out according to the method in Example 2, and the effect was similar to that in Example 2 and had no significant difference. This shows that the peppermint essential oil was tried in the form of an emulsion and achieved significant results.

[0117] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Application of peppermint essential oil in controlling ham pests.

2. A peppermint essential oil emulsion for controlling ham pests, characterized in that: The composition comprises the following components in parts by weight: The invention comprises 1-10% peppermint essential oil, 1-3% chitosan, 1% cosolvent aqueous solution, 0.5-1.5% plasticizer, 0.5-1.5% emulsifier and the balance is water.

3. The peppermint essential oil emulsion according to claim 1, characterized in that The aqueous solution of the co-solvent includes one or more of acetic acid, lactic acid, citric acid, malic acid, ascorbic acid, acetic acid, tartaric acid, and phosphoric acid.

4. The peppermint essential oil emulsion according to claim 1, characterized in that The plasticizer includes one or more of glycerol, tributyl citrate, acetyl tributyl citrate, epoxidized soybean oil, sorbitan fatty acid ester, epoxidized linseed oil, and polyethylene glycol.

5. The peppermint essential oil emulsion according to claim 1, characterized in that The emulsifier includes one or more of Tween, calcium carbonate, span, fatty acid salt, sulfate, gelatin, and gum arabic.

6. The method for preparing the peppermint essential oil emulsion for controlling ham pests according to claim 1, characterized in that: The following steps are involved: 1) Weighing each raw material according to the weight portion; 2) dissolving chitosan in the aqueous solution of the co-solvent and mixing them uniformly to obtain a solution A; 3) uniformly mixing solution A and plasticizer to obtain solution B; 4) Evenly mixing solution B, peppermint essential oil and emulsifier to obtain a peppermint essential oil emulsion for controlling ham pests.

7. The preparation method according to claim 4, characterized in that: In the step 2), the mixing temperature is 20-30° C. and the mixing time is 2-6 hours.

8. The use of the peppermint essential oil emulsion according to claim 2 in controlling ham pests, characterized in that: The ham pests include cheese flies, putrescent tyrophagous mites, and red-necked coconut beetles.

9. The use according to claim 8, characterized in that: The control methods include repelling, suppressing, contact killing or fumigating.

10. The use according to claim 8, characterized in that: The stages of control of ham pests include the eggs, larvae, pupae and adults of the pests.

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