Cinnamaldehyde oleogel and preparation method thereof

Abstract

The invention relates to cinnamyl aldehyde oleogel and a preparation method thereof. The preparation method comprises the following steps: weighing a certain amount of linseed oil, putting the linseed oil into a beaker, and carrying out magnetic heating and stirring; adding the 12-hydroxystearic acid into the linseed oil, and stirring until the 12-hydroxystearic acid is completely dissolved; after the temperature is reduced, adding cinnamyl aldehyde, and stirring to obtain a clear and transparent solution; and after uniformly stirring, stopping heating and stirring, and naturally cooling to room temperature to obtain the cinnamyl aldehyde oleogel. According to the invention, 12-hydroxystearic acid is adopted as a gel agent, and cinnamyl aldehyde is encapsulated by an oleogel system, so that cinnamyl aldehyde is slowly released, and the antibacterial activity of cinnamyl aldehyde is prolonged. The invention further relates to cinnamyl aldehyde oil gel particles and application thereof. The cinnamyl aldehyde oil gel particles are used for preventing fruits from mildewing and rotting in the long-term storage or long-distance transportation process.

Description

Technical Field

[0001] The invention relates to the field of antibacterial and mildew-proof materials for fruit preservation, and in particular to a cinnamaldehyde oil gel and a preparation method thereof. Background Art

[0002] Essential oils come from natural plants, have highly effective and broad-spectrum antibacterial properties, are safe and non-toxic, and do not produce microbial resistance. They have broad application prospects in many fields such as food antibacterial preservation, and cosmetics.

[0003] Cinnamon oil is extracted from cinnamon bark, cinnamon leaves, cinnamon roots and osmanthus flowers. Cinnamaldehyde is the main component of cinnamon oil that exerts antibacterial properties. Studies have shown that cinnamaldehyde has strong antibacterial activity against a variety of microorganisms and is also used as an insecticide for pest control. However, because cinnamaldehyde has a strong and unique cinnamon aroma, direct use will affect the natural flavor of food, and it has poor stability, is easy to volatilize, and is easily oxidized to cinnamic acid in the air, which limits its application in areas such as food preservation.

[0004] Generally, cinnamaldehyde is encapsulated in other medium carriers to solve the above problems. The carriers currently reported for encapsulating cinnamaldehyde mainly include liposomes, protein nanoparticles, nanoemulsions, complex coacervates, and composite essential oil microcapsules formed after spray drying. However, the above encapsulation strategies all have shortcomings. For example, the stability of the liposome envelope structure is poor. During food processing, the liposome membrane is often oxidized and ruptured due to high temperature and radiation irradiation, resulting in the leakage of cinnamaldehyde. Ultrasonic emulsification is often required during the preparation of cinnamaldehyde nanoemulsions. The high-energy cavitation effect formed by high-frequency ultrasound may cause cinnamaldehyde to decompose and deteriorate. The synthesis method of protein nanoparticles is complicated, and nanoparticles are prone to agglomeration, and the ability to load cinnamaldehyde is low.

[0005] As an encapsulation body of volatile and oxidizable substances, oil gel has received extensive attention in recent years. The oil gel system is mainly composed of a gelling agent and an oil phase. Monostearic glyceryl, beeswax, etc. are often used as gelling agents, and various vegetable oils can be used as oil phases. Patent application CN117158468A discloses a deodorizing and anti-oxidative nano fish oil gel and its preparation and application. First, the gelling agent monostearic glyceryl is added to the fish oil containing lemon essential oil to prepare fish oil gel, and then soybean lecithin and whey protein isolate are used as coating agents in turn. By means of high-speed dispersion, high-pressure homogenization and pH adjustment, a double-layer coated fish oil gel system is prepared. CN116898670A uses beeswax as a gelling agent and corn germ oil as an essential oil gel as an oil phase to prepare an antibacterial and deodorizing water-absorbing protective towel. CN111588654A discloses a method for preparing thyme essential oil gel, wherein coconut oil, thyme essential oil, beeswax, and lecithin are mixed and homogenized under high pressure as the oil phase, plasma-treated whey protein isolate is used as the water phase, the oil phase and the water phase are mixed to form an oil-in-water emulsion, and an antibacterial oil gel is prepared by vacuum freeze drying technology. CN201610670964.6 uses carbomer hydrogel as a matrix to prepare a plant essential oil gel dressing that can treat gynecological diseases. US2022256842A1 discloses a new preparation based on oil gel for releasing volatile components. However, although the oil phase is the main substrate of the oil gel, it lacks functional groups that can chemically interact.

[0006] In summary, encapsulating volatile and oxidizable essential oil molecules such as cinnamaldehyde in oil gel mainly relies on the network structure of the oil gel, which acts as a physical barrier to the release of cinnamaldehyde, reduces the contact between cinnamaldehyde molecules and oxygen molecules, and avoids rapid oxidation and deterioration. This physical barrier effect plays a certain positive role in inhibiting the volatilization and oxidation of the encapsulated substances. However, relying solely on the physical barrier effect of oil gel still cannot achieve the long-term, sustained and controlled release of small molecule cinnamaldehyde that is easy to diffuse and volatile, and therefore cannot meet the needs of long-term antibacterial application scenarios (such as long-term storage of fruits in cold storage or long-distance cold chain transportation). Summary of the invention

[0007] The invention aims to provide a method for preparing cinnamaldehyde oil gel, so as to solve the problems of fast volatilization speed, short antibacterial period and easy oxidation of cinnamaldehyde.

[0008] The technical solution of the present invention is as follows.

[0009] A method for preparing cinnamaldehyde oil gel, comprising the following steps: (1) Weigh a certain amount of linseed oil into a beaker and stir it with magnetic heating; (2) adding 12-hydroxystearic acid to the linseed oil of step (1), stirring until the 12-hydroxystearic acid is completely dissolved; after cooling, adding cinnamaldehyde, stirring to obtain a clear and transparent solution; (3) After stirring evenly, stop heating and stirring, and cool naturally to room temperature to obtain cinnamaldehyde oil gel.

[0010] Furthermore, the magnetic stirring conditions in step (1) are: magnetic stirrer 500 r / min, stirring at 72 °C for 3 min.

[0011] Furthermore, the weight proportions of the linseed oil, 12-hydroxystearic acid and cinnamaldehyde are: 80-87.5 parts of linseed oil, 2.5-10 parts of 12-hydroxystearic acid, and 10 parts of cinnamaldehyde.

[0012] Furthermore, the step (2) of waiting for the temperature to cool down specifically includes waiting for the temperature to cool down to 60°C.

[0013] The invention also provides a cinnamaldehyde oil gel, which is prepared by the method.

[0014] The present invention also provides cinnamaldehyde oil gel particles, which are prepared by the cinnamaldehyde oil gel mentioned above, wherein the cinnamaldehyde oil gel is heated to 60° C. to convert the oil gel into a liquid state; the liquid is poured into a spherical mold, and the oil gel particles are obtained after cooling and solidification.

[0015] The present invention also provides an application of the cinnamaldehyde oil gel particles as described above, which is applied to preventing the mildew and rot of fruits during long-term storage or long-distance transportation. Specifically, the oil gel particles are loaded into a non-woven bag, and the non-woven bag is placed in a box or bag containing citrus, cantaloupe, mango and other fruits whose peels are prone to mildew, so that the oil gel does not directly contact the fruit, but can release cinnamaldehyde for a long time, which is used to prevent the mildew and rot of fruits during long-term storage or long-distance transportation. Beneficial Effects

[0016] The cinnamaldehyde oil gel prepared by the present invention has a stable network structure, and cinnamaldehyde is gradually released from the oil gel network, destroying the smooth morphology of the bacterial cell membrane, causing the bacterial cells to swell, and the intracellular substances to flow out, thereby inhibiting the growth of the bacteria, and having a good antibacterial effect. Cinnamaldehyde is encapsulated by the oil gel, and a sustained release of up to 40 days can be achieved, thereby extending the antibacterial performance of cinnamaldehyde; and when the oil gel is placed at room temperature for a long time, cinnamaldehyde will not be oxidized and deteriorated. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the preparation process of Example 3 of the present invention.

[0018] Figure 2This is a physical picture of the spherical mold and cinnamaldehyde oil gel particles used in the present invention.

[0019] Figure 3 Optical microscope images of the cinnamaldehyde oil gel prepared in Example 1, Example 2, and Example 3 of the present invention.

[0020] Figure 4 This is a graph showing the oil binding capacity of the cinnamaldehyde oil gel prepared in Example 1, Example 2, and Example 3 of the present invention.

[0021] Figure 5 The infrared spectra of the comparative examples and raw materials of the present invention, wherein a is an infrared spectra of comparative example 3 and raw materials: linseed oil, raw materials: cinnamaldehyde, raw materials: 12-hydroxystearic acid, raw materials: beeswax, raw materials: stearic acid; b is an infrared spectra of comparative examples 4, 5 and 6; c is a further infrared spectra of the raw materials: cinnamaldehyde, raw materials: 12-hydroxystearic acid and comparative example 4 of the present invention.

[0022] Figure 6 ] is a curve showing the change of the percentage of cinnamaldehyde release of the oil gel at room temperature over time, wherein a is the curve showing the change of the percentage of cinnamaldehyde release of the oil gel prepared in Example 1, Example 2, and Example 3 over time; b is the curve showing the change of the percentage of cinnamaldehyde release of the oil gel prepared in the raw material: cinnamaldehyde, Example 3, Comparative Example 1, and Comparative Example 2 over time.

[0023] Figure 7 It is an antibacterial effect diagram of the present invention, wherein a is a comparison of the antibacterial zones of Example 3, Comparative Example 1, Comparative Example 2 and the raw material: cinnamaldehyde on Escherichia coli; b is a comparison of the diameters of the antibacterial zones of Example 3, Comparative Example 1, Comparative Example 2 and the raw material: cinnamaldehyde on Escherichia coli; c is a comparison of the antibacterial zones of Example 3, Comparative Example 1, Comparative Example 2 and the raw material: cinnamaldehyde on Staphylococcus aureus; d is a comparison of the diameters of the antibacterial zones of Example 3, Comparative Example 1, Comparative Example 2 and the raw material: cinnamaldehyde on Staphylococcus aureus.

[0024] Figure 8 The diagram is a fresh-keeping effect diagram of the cinnamaldehyde oil gel particles and cinnamaldehyde oil gel cellulose paper of the present invention, wherein a and b are fresh-keeping application scenarios of the cinnamaldehyde oil gel cellulose paper of the present invention on bananas. c and d are fresh-keeping application scenarios of the cinnamaldehyde oil gel particles of the present invention on mandarin oranges. DETAILED DESCRIPTION

[0025] A cinnamaldehyde oil gel, the preparation process of which is as follows Figure 1 As shown, 12-hydroxystearic acid, cinnamaldehyde and linseed oil are added to a beaker in proportion, heated and stirred on a magnetic stirrer to mix evenly, and then naturally cooled to form an oil gel. The oil gel is partially enlarged to observe the microscopic network structure of the oil gel.

[0026] The cinnamaldehyde oil gel of the present invention can exert its antibacterial function for a long time, wherein the physical barrier effect of the oil gel on cinnamaldehyde, the blocking effect of the hydrogen bond network between 12-hydroxystearic acid molecules on the diffusion transmission of cinnamaldehyde molecules, and the dynamic and reversible hemiacetal reaction between 12-hydroxystearic acid molecules and cinnamaldehyde molecules further increase the diffusion resistance of cinnamaldehyde molecules.

[0027] Example 1

[0028] A method for preparing a cinnamaldehyde oil gel comprises the following steps: adding 8.75 g of linseed oil to a beaker, and stirring at 72°C for 3 min using a magnetic stirrer at 500 r / min. Then, adding 0.25 g of 12-hydroxystearic acid, and stirring until the 12-hydroxystearic acid is completely dissolved. After the temperature is cooled to 60°C, adding 950 μL of cinnamaldehyde, and stirring for 1 min. After stirring evenly, stopping heating and stirring, cooling naturally to room temperature, and placing the formed oil gel in a glass culture dish.

[0029] In the oil gel, a dynamic and reversible hemiacetal chemical bonding occurs between cinnamaldehyde and 12-hydroxystearic acid. The chemical bonding gives the oil gel a more sustained release of cinnamaldehyde than conventional oil gels, thereby solving the problem that conventional oil gels are difficult to achieve long-term antibacterial effects using easily diffusible and volatile small molecule cinnamaldehyde only by physical barrier effect.

[0030] Example 2

[0031] A method for preparing a cinnamaldehyde oil gel comprises the following steps: adding 8.5 g of linseed oil to a beaker, and stirring at 72°C for 3 min using a magnetic stirrer at 500 r / min. Then, adding 0.5 g of 12-hydroxystearic acid, and stirring until the 12-hydroxystearic acid is completely dissolved. After the temperature is cooled to 60°C, adding 950 μL of cinnamaldehyde, and stirring for 1 min. After stirring evenly, stopping heating and stirring, cooling naturally to room temperature, and placing the formed oil gel in a glass culture dish.

[0032] Example 3

[0033] A method for preparing a cinnamaldehyde oil gel comprises the following steps: adding 8 g of linseed oil to a beaker, stirring at 500 r / min and 72°C for 3 min using a magnetic stirrer. Then, adding 1 g of 12-hydroxystearic acid, stirring until the 12-hydroxystearic acid is completely dissolved. After the temperature is cooled to 60°C, adding 950 μL of cinnamaldehyde, stirring for 1 min. After stirring evenly, stopping heating and stirring, cooling naturally to room temperature, and placing the formed oil gel in a glass culture dish.

[0034] Figure 31 is an optical microscope image of Example 1, Example 2, and Example 3 of the present invention. Figure 3 As shown in the figure, cinnamaldehyde-rich oil gels were successfully prepared using linseed oil and 12-hydroxystearic acid in different mass ratios. OG2.5, OG5, and OG10 represent the oil gels of Example 1, Example 2, and Example 3, respectively. As the amount of 12-hydroxystearic acid added increases, the transparency of the oil gel gradually decreases. The light transmittance of the oil gel is related to the aggregation structure of the molecules in the gel. Figure 3 It can be seen that the oil gel of Example 1 is transparent, and the microscope photograph shows a uniform, undifferentiated amorphous structure. As the concentration of 12-hydroxystearic acid increases, the gel becomes more and more opaque, and the microstructure shows obvious differentiation. The opacity of the gel and the obvious differentiated microstructure are due to the fact that 12-hydroxystearic acid forms locally ordered crystalline regions through intermolecular hydrogen bonding, and these large and small crystalline regions are diffusely distributed in the oil gel. As the content of 12-hydroxystearic acid increases, the crystalline regions become more and more obvious, and the gel of Example 3 presents a rose-shaped differentiated structure. This crystalline network structure can improve the structural stability of the oil gel, so that the cinnamaldehyde molecules distributed therein have greater diffusion and transmission resistance.

[0035] Oil binding capacity is one of the important physical properties of oil gels, reflecting the degree to which the oil gel factor entraps liquid oil in the three-dimensional gel network. Figure 4 : is the oil binding capacity diagram of cinnamaldehyde oil gel. With the increase of 12-hydroxystearic acid content, the oil binding capacity of the gel increases significantly. The oil gel of Example 3 has an oil binding capacity of 99.5%, which is sufficient to form a stable gel network. 12-hydroxystearic acid forms a three-dimensional network structure by mutual entanglement between molecular chains and hydrogen bonding forces, which intercepts and restricts the movement of oil molecules and cinnamaldehyde molecules dissolved therein, thereby hindering the release of cinnamaldehyde molecules to a certain extent.

[0036] Comparative Example 1 A method for preparing a beeswax cinnamaldehyde oil gel comprises the following steps: adding 8 g of linseed oil to a beaker, stirring with a magnetic stirrer at 500 r / min and 60°C for 3 min. Then adding 1 g of beeswax, stirring until the beeswax is completely dissolved. Adding 950 μL of cinnamaldehyde, stirring for 1 min. After stirring evenly, stopping heating and stirring, cooling naturally to room temperature, and placing the formed oil gel in a glass culture dish.

[0037] Comparative Example 2 A method for preparing stearic acid cinnamaldehyde oil gel comprises the following steps: adding 8 g of linseed oil to a beaker, stirring at 500 r / min and 67°C for 3 min using a magnetic stirrer. Then, adding 1 g of stearic acid, stirring until the stearic acid is completely dissolved. After the temperature is cooled to 60°C, adding 950 μL of cinnamaldehyde, stirring for 1 min. After stirring evenly, stopping heating and stirring, cooling naturally to room temperature, and placing the formed oil gel in a glass culture dish.

[0038] Comparative Example 3 A method for preparing a mixture of cinnamaldehyde and linseed oil comprises the following steps: adding 8 g linseed oil and 950 μL cinnamaldehyde into a beaker, stirring the mixture at 500 r / min for 1 min using a magnetic stirrer, and pouring the mixture into a centrifuge tube after stirring evenly.

[0039] Comparative Example 4 A method for preparing a mixture of cinnamaldehyde and 12-hydroxystearic acid comprises the following steps: adding 1 g of 12-hydroxystearic acid and 950 μL of cinnamaldehyde into a beaker, stirring the mixture at 500 r / min and 72° C. for 3 min using a magnetic stirrer, and pouring the mixture into a centrifuge tube after stirring evenly.

[0040] Comparative Example 5 A method for preparing a mixture of cinnamaldehyde and stearic acid comprises the following steps: adding 1 g of stearic acid and 950 μL of cinnamaldehyde into a beaker, stirring the mixture at 500 r / min and 67° C. for 3 min using a magnetic stirrer, and pouring the mixture into a centrifuge tube after stirring evenly.

[0041] Comparative Example 6 A method for preparing a mixture of cinnamaldehyde and beeswax, comprising the steps of: adding 1 g of beeswax and 950 μL of cinnamaldehyde into a beaker, stirring the mixture at 500 r / min and 60° C. for 3 min using a magnetic stirrer, and pouring the mixture into a centrifuge tube after stirring evenly.

[0042] Figure 5 In a, the infrared spectrum of comparative example 3 of the present invention, raw material: linseed oil, raw material: cinnamaldehyde, raw material: 12-hydroxystearic acid, raw material: beeswax, raw material: stearic acid. As shown in the figure, the infrared spectrum is between 1500 and 1800 cm -1 The absorption peaks in the range can be attributed to the stretching vibration of C=O in the carboxyl group, ester group and aldehyde group. Among them, for the raw material: 12-hydroxystearic acid, the center position of the C=O double bond vibration absorption peak in the carboxyl group is located at 1698 cm -1 , Raw materials: The C=O double bond vibration absorption peak of the aldehyde group in cinnamaldehyde is located at 1677 cm -1 , while the C=O double bond vibration absorption peak of the ester group in the raw material: linseed oil is located at 1744 cm -1The absorption peaks of the three C=O double bonds are strong and sharp. The infrared spectrum of the mixed solution of cinnamaldehyde and linseed oil (Comparative Example 3) is at 1500~1800 cm -1 There are two sharp and strong absorption peaks in the range, with the center positions of the peaks located at 1677 and 1744 cm -1 , which are respectively attributed to the C=O double bond vibration absorption of the aldehyde group and the ester group. The other absorption peaks of the mixture also correspond to the characteristic absorption peaks of the corresponding functional groups in the infrared spectrum of the raw material: cinnamaldehyde or the raw material: linseed oil, that is, the infrared spectrum of the mixture is actually the superposition of the infrared absorption spectra of the raw material: cinnamaldehyde and the raw material: linseed oil. The above information shows that in the mixed solution of cinnamaldehyde and linseed oil (Comparative Example 3), there is no chemical interaction between the two. What is significantly different from the C=O stretching vibration peak of the cinnamaldehyde and linseed oil solution is that Figure 5 As shown in b, for the mixed solution of cinnamaldehyde and 12-hydroxystearic acid (Comparative Example 4), the -1 The C=O stretching vibration peak in the range showed significant broadening and red shift, such as Figure 5 As shown in Figure c, the infrared spectra of the raw material: cinnamaldehyde, the raw material: 12-hydroxystearic acid and comparative example 4 are placed separately in the same figure, and it can be more clearly and intuitively seen that the C=O stretching vibration peak has undergone a significant red shift. In addition, it should be pointed out that the broadening phenomenon of the C=O stretching vibration peak only appears in the infrared spectrum of the mixed solution of cinnamaldehyde and 12-hydroxystearic acid (Comparative Example 4), but is not observed in the infrared spectrum of the mixed solution of stearic acid (Comparative Example 5) or beeswax (Comparative Example 6) and cinnamaldehyde. Considering that hydroxyl and aldehyde groups can undergo hemiacetal reaction under milder conditions, the obvious broadening phenomenon of the C=O absorption peak can be attributed to the dynamic reversible hemiacetal reaction between the hydroxyl group of 12-hydroxystearic acid and the C=O functional group of cinnamaldehyde, as shown in Formula I, which is the structural formula of cinnamaldehyde and 12-hydroxystearic acid, and under what conditions this reversible condensation reaction can be carried out. This dynamic reversible hemiacetal reaction can further increase the diffusion resistance of cinnamaldehyde molecules.

[0043]

[0044] Figure 6The evolution curves of the percentage of cinnamaldehyde released within 40 days of the oil gel (a) prepared in Example 1, Example 2, and Example 3, the raw material: cinnamaldehyde, and the oil gel (b) of Example 3, Comparative Example 1, and Comparative Example 2 are shown. In a, as the content of 12-hydroxystearic acid increases, the release of cinnamaldehyde becomes slower and slower, mainly due to the restriction of the three-dimensional network structure formed by 12-hydroxystearic acid on the diffusion of cinnamaldehyde molecules. In b, compared with the raw material: cinnamaldehyde, all oil gels can significantly slow down the release of cinnamaldehyde molecules. In addition, different gelling agents also have a significant effect on the release rate of cinnamaldehyde. When the amount of gelling agent added is the same (10%), the cinnamaldehyde release rate of 12-hydroxystearic acid oil gel (Example 3) is the slowest. Combined with infrared spectroscopy analysis, this significant difference is attributed to the chemical interaction between the gelling agent molecules and the cinnamaldehyde molecules. Infrared spectrum ( Figure 5 ) shows that only 12-hydroxystearic acid and cinnamaldehyde molecules can undergo a dynamic and reversible hemiacetal reaction. Cinnamaldehyde diffuses and transmits in the oil gel. In the beeswax (Comparative Example 1) and stearic acid (Comparative Example 2) oil gel systems, the cinnamaldehyde molecules are only physically blocked by the oil gel, while in the 12-hydroxystearic acid oil gel system (Example 3), in addition to the physical barrier effect of the oil gel, the dynamic and reversible hemiacetal chemical bond and action between 12-hydroxystearic acid and cinnamaldehyde molecules further increase the diffusion resistance of the cinnamaldehyde molecules.

[0045] Encapsulating cinnamaldehyde in oil gel can slow down its release rate to a certain extent. However, it can be seen from Comparative Examples 1 and 2 that the long-term (>40 days) controllable release of cinnamaldehyde molecules cannot be achieved by relying solely on the physical barrier effect of oil gel, and therefore still cannot meet the needs of mildew prevention and preservation during long-term storage of food.

[0046] The antibacterial activity of cinnamaldehyde oil gel against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) was evaluated by the inhibition zone method. Figure 7It can be seen from a and c that when the cinnamaldehyde loading is the same, the inhibition zone of the raw material: cinnamaldehyde is the largest. This is because the diffusion and volatilization of the raw material: cinnamaldehyde molecules are not hindered, and the largest antibacterial action area can be formed. For the three freshly prepared oil gels (Example 3, Comparative Example 1, Comparative Example 2), the diameters of the inhibition zones placed for 0 days are very different. This is because the content of cinnamaldehyde in all oil gels is the same at this time, and the driving force for cinnamaldehyde to diffuse from the oil gel to the surroundings is the same. However, as the placement time increases, the residual amount of cinnamaldehyde in the oil gel changes due to differences in the cinnamaldehyde release rates of the three oil gels. The greater the cinnamaldehyde release rate, the less cinnamaldehyde residue in the oil gel, the smaller the driving force for cinnamaldehyde to diffuse into the surrounding space, and the size of the inhibition zones tested on the 10th, 21st and 34th days begins to show significant differences. The inhibition zone of the 12-hydroxystearic acid system (Example 3) has the smallest reduction, and the inhibition zone of the beeswax system (Comparative Example 1) has the largest reduction. This result is consistent with the cinnamaldehyde release curve ( Figure 6 Corresponding to b).

[0047] Encapsulating cinnamaldehyde in an oil gel can slow down its release rate to a certain extent. However, it can be seen from Comparative Examples 1 and 2 that the long-term (>40 days) controllable release of cinnamaldehyde molecules cannot be achieved by relying solely on the physical barrier effect of the oil gel. Based on this, the present invention introduces strong chemical interactions such as hydrogen bonds and dynamic covalent bonds on the basis of the physical barrier effect of the oil gel, further increasing the diffusion resistance of small molecule cinnamaldehyde in the oil gel system, thereby achieving the purpose of sustained release of cinnamaldehyde. The oil gel system is mainly composed of a gelling agent and an oil phase. Although the oil phase is the main substrate of the oil gel, it lacks functional groups that can chemically interact. The oil gel system using 12-hydroxystearic acid as a gelling agent can achieve ultra-long release of cinnamaldehyde molecules.

[0048] In conventional oil gel, oil and gelling agent molecules form a three-dimensional spatial network structure, and the three-dimensional network structure plays a physical barrier role on the diffusion and migration of volatile active components, thereby delaying the release of volatile active molecules. However, for small molecular weight, easy migration, and volatile small molecule active substances, such as cinnamaldehyde, the physical barrier of oil gel alone still cannot meet the demand for long-term sustained release. In order to give oil gel a more long-term sustained release performance for volatile small molecule cinnamaldehyde than conventional oil gel, the oil gel designed by the present invention not only utilizes the physical barrier effect of the three-dimensional network structure, but also specifically introduces covalent bonds and effects, that is, 12-hydroxystearic acid is selected as a gelling agent in a targeted manner, and the dynamic reversible hemiacetal reaction between the hydroxyl group of the gelling agent and the aldehyde group of cinnamaldehyde is utilized to further increase the diffusion and migration resistance of the cinnamaldehyde molecules.

[0049] The present invention mainly discloses an oil gel system in which a molecule represented by 12-hydroxystearic acid and capable of having a strong chemical interaction with cinnamaldehyde molecules is used as a gelling agent, and the ultra-long controlled release of cinnamaldehyde molecules is achieved. When placed in the open at room temperature, the antibacterial activity is greater than 40 days. The structural characteristics of such gelling agent molecules are that they contain hydroxyl groups and carboxyl groups at the same time, and a carbon chain (such as 10 carbon atoms) of appropriate length is spaced between the hydroxyl groups and the carboxyl groups. Such gelling agent molecules can form a hydrogen bond network structure in the oil gel, which can hinder the diffusion of cinnamaldehyde molecules. In addition, such gelling agent molecules can undergo a dynamic and reversible hemiacetal reaction through the hydroxyl groups and the aldehyde groups of cinnamaldehyde, and this dynamic covalent bonding can further increase the diffusion resistance of cinnamaldehyde molecules in the oil gel. The physical barrier effect of the oil gel, the hydrogen bond network structure between the gelling agent molecules, and the reversible covalent bonding between the gelling agent molecules and the cinnamaldehyde molecules are exerted simultaneously, and finally the controlled and long-acting release of the cinnamaldehyde molecules is achieved. The present invention is of great significance for promoting the application of volatile and easily oxidizable essential oil active small molecules with antibacterial and fresh-keeping functions in the field of food preservation.

[0050] When used, the cinnamaldehyde oil gel obtained in the present application is made into small particles (or coated on cellulose paper), and then the oil gel particles (or oil gel cellulose paper) are put into a non-woven bag, and the non-woven bag is placed in a box or bag for fruits such as citrus, cantaloupe, mango, etc. whose peels are prone to mold. The oil gel does not directly contact the fruit, but can release cinnamaldehyde for a long time, and is used to prevent the fruit from mold and rot during long-term storage or long-distance transportation.

[0051] As an embodiment of the present application, the present application also provides a cinnamaldehyde oil gel particle, which is further prepared by using the cinnamaldehyde oil gel prepared by the preparation method described in Example 3, specifically, the prepared cinnamaldehyde oil gel is heated to 60°C, so that the oil gel is converted into a liquid state. This liquid is poured into a spherical mold (see Figure 2 a), after cooling and solidification, the oil gel particles with a particle size of 5 mm were obtained (see Figure 2 b) The mass of the oil gel particles is 0.14±0.01 g / particle.

[0052] As an embodiment of the present application, the present application also applies the cinnamaldehyde oil gel particles to prevent the mildew and rot of fruits during long-term storage or long-distance transportation. Specifically, the oil gel particles are put into a non-woven bag, and the non-woven bag is placed in a box or bag containing citrus, cantaloupe, mango and other fruits whose peels are prone to mildew, so that the oil gel does not directly contact the fruit, but can release cinnamaldehyde for a long time, which is used to prevent the mildew and rot of fruits during long-term storage or long-distance transportation. Figure 8As a food preservative material, cinnamaldehyde oil gel does not directly contact food during actual application, but uses slowly released cinnamaldehyde to achieve antibacterial, antiseptic and fresh-keeping effects on food. A and B are application scenarios of the cinnamaldehyde oil gel cellulose paper of the present invention for preserving bananas. C and D are application scenarios of the cinnamaldehyde oil gel particles of the present invention for preserving mandarin oranges.

[0053] As an ideal low molecular weight organic gelling agent, 12-Hydroxystearic acid is widely used in industrial production, including food industry and medicine, because of its low dosage, relative non-toxicity and easy availability. Although nearly 40 years ago, the Chemical Industry Press published the "Chemical Product Handbook Organic Chemical Raw Materials" Volume 1, first edition in 1985, page 460 mentioned that 12-hydroxystearic acid was a low-toxic product. However, in recent years, domestic and foreign research fields generally recognize that 12-hydroxystearic acid can be used as a new type of structured gelling agent in edible oil systems such as spreads, chocolate candies and health foods, or as a drug carrier. In addition, in 2016, the National Health and Family Planning Commission issued the "Announcement on 23 New Varieties of Food-Related Products Including Poly (12-Hydroxystearic Acid) Stearate (No. 7 of 2016)". The announcement clearly states that poly (12-hydroxystearic acid) stearate can be used as a new type of additive for food contact materials and products, and clearly states that the U.S. Food and Drug Administration and the European Commission have also approved its use in food contact materials and products.

[0054] The present invention provides an oil gel with 12-hydroxystearic acid as a gelling agent, linseed oil as an oil phase, and cinnamaldehyde. A dynamic reversible hemiacetal reaction occurs between 12-hydroxystearic acid and cinnamaldehyde. With the help of this chemical bonding and the physical barrier effect originally possessed by the oil gel, the diffusion and transmission resistance of small molecule cinnamaldehyde in the oil gel is significantly increased, thereby achieving the purpose of long-term antibacterial and mildew prevention by means of the controllable release of cinnamaldehyde by the oil gel. Microbial culture experiments show that the 12-hydroxystearic acid oil gel prepared by the present invention can achieve the effect of continuous and effective release of cinnamaldehyde for up to 34 days at room temperature, while for oil gels prepared with other gelling agents such as beeswax and stearic acid, the effective release time of cinnamaldehyde under the same conditions is only 20 days at most, and after 20 days, the diameter of the inhibition zone decreases rapidly. This fully illustrates that, in addition to the physical barrier effect, the introduction of chemical bonding in the oil gel system can more effectively control the release of small molecule cinnamaldehyde that is easy to diffuse and migrate and volatile.

[0055] The present invention may be summarized in other specific forms that do not violate the spirit or main features of the present invention. Therefore, no matter from which point of view, the above embodiments of the present invention can only be regarded as an explanation of the present invention and cannot limit the present invention. The claims indicate the scope of the present invention, while the above description does not indicate the scope of the present invention. Therefore, any changes within the meaning and scope equivalent to the claims of the present invention should be considered to be included in the scope of the claims of the present invention.

Claims

1. A method for preparing cinnamaldehyde oil gel, characterized in that: The steps include: (1) Weigh a certain amount of linseed oil into a beaker and stir it with magnetic heating; (2) adding 12-hydroxystearic acid to the linseed oil of step (1), stirring until the 12-hydroxystearic acid is completely dissolved; after cooling, adding cinnamaldehyde, stirring to obtain a clear and transparent solution; (3) After stirring evenly, stop heating and stirring, and cool naturally to room temperature to obtain cinnamaldehyde oil gel.

2. The preparation method according to claim 1, characterized in that The magnetic stirring conditions in step (1) are: magnetic stirrer 500 r / min, stirring at 72 °C for 3 min.

3. The preparation method according to claim 1, characterized in that: The weight proportions of the linseed oil, 12-hydroxystearic acid and cinnamaldehyde are: 80-87.5 parts of linseed oil, 2.5-10 parts of 12-hydroxystearic acid, and 10 parts of cinnamaldehyde.

4. The preparation method according to claim 1, characterized in that: The temperature in step (2) is cooled to 60°C.

5. A cinnamaldehyde oil gel, characterized in that Prepared by the preparation method according to any one of claims 1 to 4.

6. A cinnamaldehyde oil gel particle, characterized in that: The cinnamaldehyde oil gel as described in claim 5 is prepared, and the cinnamaldehyde oil gel is heated to 60° C. to convert the oil gel into a liquid state; the liquid is poured into a spherical mold, and the oil gel particles are obtained after cooling and solidification.

7. A use of the cinnamaldehyde oil gel particles as claimed in claim 6, characterized in that: Used to prevent fruits from mildew and rot during long-term storage or long-distance transportation.

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