阅读说明：本技术 一种微乳化复合植物精油大米保鲜剂的制备方法 (Preparation method of micro-emulsified composite plant essential oil rice preservative ) 是由 龚吉军 卢锟 龚晟兰 王挥 唐静 于 2020-08-31 设计创作，主要内容包括：一种微乳化复合植物精油大米保鲜剂的制备方法,包括以下步骤：丁香花、迷迭香叶、蓝桉叶、百里香叶、肉桂皮、大蒜籽和山苍子单一植物精油的分别提取；将单一植物精油混合成复合植物精油；复合表面活性剂制备；将所述复合植物精油与所述复合表面活性剂混合、微乳化,即成。本发明所得大米保鲜剂对导致大米霉变的真菌具有广谱的抑菌效果,其抑菌效果优于单一植物精油；可大幅减少大米的霉变,延长大米的保鲜期,同时不影响大米的感官品质；同时不影响大米的感官品质；本发明中的精油提取方法有较高的精油得率；成本低廉,使用方便,无污染；对提高储粮的安全性及推动植物精油产业的健康、可持续发展均具有良好的作用,其经济、社会和生态效益显著。(A preparation method of a micro-emulsified composite plant essential oil rice preservative comprises the following steps: respectively extracting single plant essential oil of clove flower, rosemary leaf, eucalyptus globulus leaf, thyme leaf, cinnamon bark, garlic seed and litsea cubeba; mixing single plant essential oil into composite plant essential oil; preparing a composite surfactant; mixing the compound plant essential oil and the compound surfactant, and performing micro-emulsification to obtain the plant essential oil. The rice preservative has broad-spectrum antibacterial effect on fungi causing rice mildew, and the antibacterial effect of the rice preservative is superior to that of single plant essential oil; the mildew of the rice can be greatly reduced, the preservation period of the rice is prolonged, and the sensory quality of the rice is not influenced; meanwhile, the sensory quality of the rice is not influenced; the essential oil extraction method has higher essential oil yield; the cost is low, the use is convenient, and no pollution is caused; has good effects on improving the safety of grain storage and promoting the healthy and sustainable development of the plant essential oil industry, and has remarkable economic, social and ecological benefits.)

1. A preparation method of a micro-emulsified composite plant essential oil rice preservative is characterized by comprising the following steps:

(1) respectively taking dried clove flowers, dried rosemary leaves, dried eucalyptus globulus leaves, dried thyme leaves, dried cinnamon bark, fresh garlic seeds and fresh litsea cubeba as plant raw materials to carry out single plant essential oil extraction;

(2) compounding of single plant essential oil: mixing flos Caryophylli essential oil, herba Rosmarini officinalis essential oil, Eucalyptus globulus Labill leaf essential oil, herba Thymi essential oil, cortex Cinnamomi essential oil, Bulbus Allii essential oil and fructus Litseae essential oil uniformly to obtain composite plant essential oil;

(3) preparing a composite surfactant: mixing the polyoxyethylene castor oil 30 solution with absolute ethyl alcohol to obtain a composite surfactant;

(4) mixing and microemulsifying the composite plant essential oil and the composite surfactant: mixing the compound plant essential oil and the compound surfactant in a closed container under stirring, continuously stirring and injecting ultrapure water to obtain the microemulsion.

2. The preparation method of the microemulsified composite plant essential oil rice preservative according to claim 1, wherein the method for extracting the single plant essential oil in the step (1) comprises the following steps:

a) crushing raw materials: taking the plant raw materials, cleaning, roughly crushing, adding distilled water, and crushing by using a high-speed tissue triturator to obtain plant pulp;

b) pretreatment by ultrasonic waves: treating the plant pulp by ultrasonic waves to obtain ultrasonic treatment liquid;

c) steam distillation: reducing the material-liquid ratio of the ultrasonic treatment liquid, performing steam distillation, collecting plant essential oil containing a small amount of water obtained by distillation, and performing centrifugal dehydration to obtain the product.

3. The preparation method of the micro-emulsified composite plant essential oil rice preservative as claimed in claim 2, wherein in the step a), the material-liquid ratio after adding distilled water is 1g: 1-5 mL, the rotation speed of the high-speed tissue mashing machine is 5000-10000r/min, and the treatment time is 5-10 min.

4. The preparation method of the micro-emulsified composite plant essential oil rice preservative as claimed in claim 2 or 3, wherein in b), the power of ultrasonic treatment is 100-500w, and the treatment time is 18-40 min.

5. The preparation method of the micro-emulsified composite plant essential oil rice preservative according to any one of claims 2 to 4, wherein in c), the material-liquid ratio of an ultrasonic treatment liquid is adjusted to 1g: 5.1-11 mL, and the steam distillation time is 5-9 h; the rotational speed of the centrifugal dehydration is 18000-22000 r/min.

6. The preparation method of the micro-emulsified composite plant essential oil rice preservative according to any one of claims 2 to 5, wherein in c), a water layer containing a small amount of plant essential oil separated by steam distillation is added into the next batch of ultrasonic treatment liquid for steam distillation.

7. The preparation method of the micro-emulsified composite plant essential oil rice preservative according to any one of claims 2 to 6, wherein parameters adopted in the extraction process are the same when each single plant essential oil component of the composite plant essential oil is extracted respectively.

8. The preparation method of the micro-emulsified composite plant essential oil rice preservative according to any one of claims 1 to 7, wherein in the step (2), the formula of the composite plant essential oil comprises the following components in percentage by volume: 6.00-20.00% of clove essential oil, 8.0-23.0% of rosemary essential oil, 11.00-28.0% of eucalyptus globulus leaf essential oil, 10.0-25.0% of thyme essential oil, 3.0-15.0% of cinnamon essential oil, 5.0-18.0% of garlic essential oil and 15.0-33.0% of litsea cubeba essential oil.

9. The preparation method of the micro-emulsified composite plant essential oil rice preservative according to any one of claims 1 to 8, wherein in the step (3), the concentration of the polyoxyethylene castor oil 30 solution is 40-60g/L, and the volume ratio of the polyoxyethylene castor oil 30 solution to the absolute ethyl alcohol is 4-8: 9-13.

10. The preparation method of the micro-emulsified composite plant essential oil rice preservative according to any one of claims 1 to 9, wherein in the step (4), the flow rate of the composite plant essential oil is 21.8-24.6mL/min, the flow rate of the composite surfactant is 25.4-28.2mL/min, the flow rate of the ultrapure water is 130-155mL/min, and the stirring speed of a mixer is 100-500 r/min; the volume ratio of the composite plant essential oil to the composite surfactant to the ultrapure water is as follows: 10: 9-12: 40-60.

Technical Field

The invention relates to a preparation method of a plant essential oil rice preservative, and in particular relates to a preparation method of a micro-emulsified plant essential oil rice preservative.

Background

Rice (A)Oryza sativaL.) is one of the most important staple foods in our country, and about 67% of the residents use rice as a staple food.

Rice contains a certain amount of fungi, the rice mildew due to mass propagation of the fungi along with the prolonging of storage time, Penicillium islandicum (II)Penicillium islandicum) And Aspergillus flavus (Aspergillus flavus) Is a major harmful fungus growing in stored rice. The rice storage method has great significance for relieving and inhibiting the occurrence of mildewing in the rice storage process, improving the edible safety of the rice and reducing the loss of grain resources.

Controlling the storage temperature and relative humidity of rice is one of the effective ways to prevent mildew, but controlling the storage temperature and relative humidity has high energy consumption, high cost and low added value of rice, so that storage under low temperature and humidity control conditions is not a realistic option.

The irradiation technology is also one of the means for preventing rice from mildewing. However, the irradiation equipment is complex in structure, requires a radiation shielding control system and other auxiliary equipment, is high in cost, and is difficult to continuously apply.

The high energy consumption and high cost of the dielectric heating anti-mildew technology also make it difficult to realize industrial application in a short time.

The chemical antistaling agent is a traditional rice fresh-keeping mode, and has the main advantages of low cost and convenient use, and the chemical antistaling agent such as aluminum phosphide and phosphine is used for preventing mildew and insects of rice for many years. With the continuous improvement of food safety consciousness of people, the problems of chemical residue, environmental pollution, harm to human health and the like brought by the chemical preservative gradually attract attention of people.

The micro-emulsified plant essential oil preservative is a substitute of a chemical preservative with great prospect. The micro-emulsification can better solve the defects of easy volatilization and instability of the plant essential oil. The surfactant and cosurfactant added into the microemulsion are easy to form a microemulsion system spontaneously under the action of negative interfacial tension, but the microemulsion system also has the problem that the stability is difficult to maintain for a long time. Moreover, the plant essential oil components are complex, the formation of a microemulsion system is closely related to the plant essential oil components, and the difference of the interfacial tension of the microemulsion systems of the plant essential oil with different components is large, so that the steady-state system of the microemulsion plant essential oil is difficult to optimize, and the related research progresses slowly; the research on plant essential oil micro-emulsification and bacteriostatic activity thereof is only reported in individual documents so far. Zhou Han Jun (research on extraction of eucalyptus essential oil, nano-emulsification and antibacterial activity thereof, Master's academic thesis, 2016) adopts a composite surfactant composed of polyoxyethylene castor oil 30 and absolute ethyl alcohol, eucalyptus essential oil and distilled water to prepare the eucalyptus essential oil nanoemulsion according to a certain proportion, but the preparation method cannot ensure continuity and has low production efficiency, and the antibacterial effect of the obtained eucalyptus essential oil nanoemulsion needs to be improved. A preparation method of a micro-emulsified rice preservative compounded by various plant essential oils is not reported.

CN105961583A discloses a storage method of rice: before processing, mechanically drying the paddy until the water content is below 10%, and then freeze-drying; removing shells, soaking the preservative A in a preservative A, adding an emulsifier after soaking the preservative A for 1h, mechanically drying the emulsifier, putting the emulsifier into a woven bag coated with a preservative B layer and a xanthan gum layer in sequence, wherein the preservative B consists of sodium carboxymethylcellulose, quercetin, liquorice, scutellaria baicalensis and a sizing solution with the concentration of 40-60%, and then placing the preservative B in a ventilated place for storage; the method uses various antistaling agents to process rice, and the sensory quality of rice is reduced after the treatment by the method.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects in the prior art and providing a preparation method of a micro-emulsified composite plant essential oil rice preservative; the method can efficiently extract plant essential oil, the obtained composite plant essential oil has broad-spectrum inhibition effect on fungi causing rice mildew, and the obtained micro-emulsified composite plant essential oil rice preservative has good slow-release effect and can maintain antibacterial activity for a long time.

The technical scheme adopted by the invention for solving the technical problems is as follows: a preparation method of a micro-emulsified composite plant essential oil rice preservative comprises the following steps:

(1) respectively taking dried clove flowers, dried rosemary leaves, dried eucalyptus globulus leaves, dried thyme leaves, dried cinnamon bark, fresh garlic seeds and fresh litsea cubeba as plant raw materials to carry out single plant essential oil extraction;

(2) compounding of single plant essential oil: mixing clove essential oil, rosemary essential oil, eucalyptus globulus leaf essential oil, thyme essential oil, cinnamon essential oil, garlic essential oil and litsea cubeba essential oil into the composite plant essential oil;

(3) preparing a composite surfactant: mixing polyoxyethylene castor oil 30 (Cremophor EL 30) solution with absolute ethyl alcohol to obtain a composite surfactant;

(4) mixing and micro-emulsifying the compound plant essential oil and the compound surfactant: mixing the compound plant essential oil and the compound surfactant in a closed container under stirring, continuously stirring and injecting ultrapure water to obtain the microemulsion.

Preferably, the method for extracting the single plant essential oil in the step (1) comprises the following steps:

a) crushing raw materials: taking the plant raw materials, cleaning, roughly crushing, adding distilled water, and crushing by using a high-speed tissue triturator to obtain plant pulp;

b) pretreatment by ultrasonic waves: treating the plant pulp by ultrasonic waves to obtain ultrasonic treatment liquid;

c) steam distillation: reducing the material-liquid ratio of the ultrasonic treatment liquid, performing steam distillation, collecting plant essential oil containing a small amount of water obtained by distillation, and performing centrifugal dehydration to obtain the product.

Preferably, in a), the ratio of material to liquid after adding distilled water is 1g: 1-5 mL (more preferably 1g: 2-4 mL), the rotation speed of the high-speed tissue triturator is 5000-.

Preferably, in b), the power of the ultrasonic treatment is 100-.

Preferably, in c), the feed-liquid ratio of the ultrasonic treatment liquid is adjusted to 1g: 5.1-11 mL (more preferably 1: 6-10), and the steam distillation time is 5-9h (more preferably 6-8 h); the rotation speed of the centrifugal dehydration is 18000-22000r/min (more preferably 19000-21000 r/min).

Preferably, in c), the water layer containing a small amount of plant essential oil separated by steam distillation is added into the next batch of ultrasonic treatment liquid for steam distillation.

Yield of plant essential oil/% = weight of plant essential oil (g)/weight of raw material (g) × 100%

The yield of clove essential oil, rosemary essential oil, eucalyptus globulus labdani leaf essential oil, thyme essential oil, cinnamon essential oil, garlic essential oil and litsea cubeba essential oil in the method for extracting single plant essential oil is respectively (20.840 +/-0.065)% (n =5), (2.877 +/-0.003)% (n =5), (1.739 +/-0.008)% (n =5), (1.688 +/-0.006)% (n =5), (1.900 +/-0.010)% (n =5), (0.394 +/-0.005)% (n =5) and (3.541 +/-0.006)% (n = 5). The dehydrated plant essential oil can be sealed and stored at 0 deg.C for use.

The method for extracting the plant essential oil has higher essential oil yield, and the compound plant essential oil obtained by compounding the obtained plant essential oil has broad-spectrum antibacterial effect on rice.

Preferably, when each single plant essential oil component of the composite plant essential oil is extracted respectively, the parameters adopted in the extraction process are the same.

Preferably, in the step (2), the formula of the compound plant essential oil comprises the following components in percentage by volume: 6.67-20.00% of clove essential oil, 8.0-23.0% of rosemary essential oil, 11.0-28.0% of eucalyptus globulus leaf essential oil, 10.0-25.0% of thyme essential oil, 3.0-15.0% of cinnamon essential oil, 5.0-18.0% of garlic essential oil and 15.0-33.0% of litsea cubeba essential oil.

More preferably, the formula of the compound plant essential oil comprises the following components in percentage by volume: 9.0-16.0% of clove essential oil, 10.0-18.0% of rosemary essential oil, 14.0-22.0% of eucalyptus globulus leaf essential oil, 12.0-20.0% of thyme essential oil, 5.0-11.0% of cinnamon essential oil, 7.0-13.0% of garlic essential oil and 18.0-26.0% of litsea cubeba essential oil.

Further preferably, the formula of the compound plant essential oil comprises the following components in percentage by volume: 11.0-13.0% of clove essential oil, 13.0-15.0% of rosemary essential oil, 17.0-19.0% of eucalyptus globulus leaf essential oil, 15.0-17.0% of thyme essential oil, 6.5-9.0% of cinnamon essential oil, 9.0-11.0% of garlic essential oil and 20.5-24.0% of litsea cubeba essential oil.

Preferably, in the step (3), the concentration of the polyoxyethylene castor oil 30 (Cremophor EL 30) solution is 40-60g/L (more preferably 45-55 g/L), and the volume ratio of the polyoxyethylene castor oil 30 (Cremophor EL 30) solution to the absolute ethyl alcohol is 4-8:9-13 (more preferably 5-7: 10-12).

Preferably, in the step (4), the flow rate of the composite plant essential oil is 21.8-24.6mL/min (more preferably 22.4-23.8 mL/min), the flow rate of the composite surfactant is 25.4-28.2mL/min (more preferably 26.2-27.6 mL/min), the flow rate of the ultrapure water is 130-.

Preferably, in the step (4), the volume ratio of the compound plant essential oil, the compound surfactant and the ultrapure water is as follows: 10:9 to 12:40 to 60 (more preferably 10:10 to 11:45 to 55).

Plant essential oil, also called essential oil, aromatic oil or volatile oil, is a generic name of a volatile oily component which has aromatic odor and can be distilled with water vapor and is immiscible with water and is a secondary metabolite of plants. The clove essential oil, the rosemary essential oil, the eucalyptus globulus leaf essential oil, the thyme essential oil, the cinnamon essential oil, the garlic essential oil and the litsea cubeba essential oil are common food flavors, are good in safety, are prepared into the slow-release preservative after being subjected to micro-emulsification, and are convenient to use.

The micro-emulsified composite plant essential oil rice preservative prepared by the method can effectively control the release speed of the plant essential oil so as to obtain a long-term preservation effect, and has no obvious influence on the sensory quality of rice and cooked rice.

The method can realize continuous production, is simple to operate, has high production efficiency, is stable after being placed for 365d at normal temperature, and is superior to the technologies reported in various existing documents.

The rice preservative prepared by the method is used for mildew prevention and preservation of rice,new rice rolled out from Xiang late long-shaped No. 17 with the dry water content lower than 13.5 percent is taken as an object, the new rice is packaged by PC bags with the specification of 30cm multiplied by 50cm and the thickness of 0.1mm without vacuumizing, 5Kg of preservative prepared according to the method and packaged by non-woven small bags is added into each bag, the bags are sealed, 10g of rice is randomly taken when the rice is stored at the constant temperature of 25 ℃ to the 90 th day, the method of GB4789.15-2010 is adopted to measure the total number of moulds, the average total number of moulds in preservative treatment groups is a blank control group (except that the preservative is not used for treatment, the other treatments are completely consistent) or 7 single essential oil control groups (except that the 7 single plant essential oils are used for treatment according to microemulsion prepared according to the same preparation method as the 7 composite essential oil preservatives, the other treatments are completely consistent), and the method has the obvious effects (the method is thatp<0.01). After 90 days, the sensory quality of the rice preserved by the antistaling agent is compared with that of the rice cooked by fresh rice milling, and no obvious difference exists (p>0.05)。

The invention has the beneficial effects that:

(1) the rice preservative prepared by the method has good mildew-proof and fresh-keeping effects on rice, and does not influence the sensory quality of the rice;

(2) the rice preservative prepared by the method adopts natural plant essential oil as an anti-mildew active ingredient, and has the advantages of low cost, convenient use and no pollution;

(3) the rice preservative prepared by the method can keep the stability of a microemulsion system for a long time (365 d) under the normal-temperature sealing condition;

(4) the preparation method of the invention has higher essential oil yield, and the compound plant essential oil obtained after compounding the obtained plant essential oil has broad-spectrum antibacterial effect on fungi causing rice mildew, and the antibacterial effect is superior to that of single plant essential oil;

(5) the invention can reduce the mildew of rice, prolong the fresh-keeping period of rice, has good effects on improving the safety of stored grains and promoting the healthy and sustainable development of the plant essential oil industry, and has remarkable economic, social and ecological benefits.

Detailed Description

The present invention will be described in further detail with reference to examples.

The clove flowers used in each example are purchased from Yulin Yuzhou area Jiayu native Chinese herbal medicine Puji, the Eucalyptus globulus leaf is purchased from Chongqing Chengtang Chinese herbal medicine sales Co., Ltd, the thyme leaf, the cinnamon bark and the rosemary leaf are purchased from Qingdao and food ingredient Co., Ltd, and the garlic seed and the litsea cubeba are common commercial products.

The chemical raw materials used in the examples are all common commercial products.