Ammonia response type cinnamyl aldehyde gel bead and preparation method thereof

Abstract

The invention discloses an ammonia response type cinnamyl aldehyde gel bead and a preparation method thereof, and belongs to the field of materials science. The preparation method comprises the following steps: adding cinnamyl aldehyde into a mixed solution composed of polysaccharide and a cross-linking agent, emulsifying to obtain a liquid core, dispersing the liquid core into a hydrophilic group material containing sodium caseinate, and finally carrying out a cross-linking reaction to obtain the gel beads. By means of casein attached to a composite wall material for synthesizing the gel beads, phosphate ester bonds on serine residues of sodium caseinate contained in the casein encounter volatile ammonia and are dephosphorylated in an alkaline atmosphere, so that the phosphate ester bonds are hydrolyzed and broken, the membrane crosslinking structure and stability of the casein are influenced, the porosity of the gel beads and the tension of internal liquid cores are controlled, and the gel beads are prepared. The function of responding to the alkaline gas is realized. Long-acting high-position release is realized in a non-touch response release manner, so that the pollution of cinnamyl aldehyde essential oil to chilled meat and the adverse influence of cinnamyl aldehyde essential oil on sense organs during preservation are reduced.

Description

Technical Field

[0001] The present invention relates to the field of materials science, and in particular to an ammonia-responsive cinnamaldehyde gel bead and a preparation method thereof. Background Art

[0002] Cinnamaldehyde belongs to aliphatic aldehydes and has broad-spectrum antibacterial properties against microorganisms. It has been approved as an additive in the food, feed, and pharmaceutical industries. However, its strong flavor, poor water solubility, easy oxidation, sensitivity to light and high temperature also limit the direct application of cinnamaldehyde in various food systems.

[0003] Existing different preservation methods have been developed and applied to the storage process of chilled meat. Currently, common preservation means on the market often adopt contact preservation methods, such as film covering, spraying or soaking. The most common way of cinnamaldehyde is to incorporate it into an edible film, which usually causes cinnamaldehyde particles on the film to be incorporated into the chilled meat, resulting in chain contamination. At the same time, the contact preservation method may cause unpleasant flavors to penetrate, thereby reducing the acceptance of consumers.

[0004] For non-contact preservation means, such as modified atmosphere packaging, radiation preservation, plasma sterilization and other preservation methods have been used to ensure the safety of chilled pork and extend its shelf life. Compared with contact preservation, non-contact preservation means reduce the impact on the sensory quality of the food itself. However, there are still many defects. It can not only be used for the preservation of inexpensive products, but also complicates the food supply chain and reduces cost-effectiveness; and there are problems in convenience, which requires specific equipment to assist, and considering the equipment line cost is higher than the cold chain operation cost. In addition, there is little research on simple and convenient non-contact preservation antibacterial agents at present. Summary of the Invention

[0005] [Technical Problem]

[0006] The technical problem to be solved by the present invention is that most current preservation methods are contact-type preservation, and their antibacterial components may interact with food, and the strong volatile flavor easily affects the sensory flavor of the food itself; non-contact preservation cannot be used for the preservation of inexpensive products, and has poor convenience and high cost.

[0007] [Technical Solution]

[0008] The present invention provides an ammonia-responsive cinnamaldehyde gel bead and a preparation method thereof, which can achieve non-contact preservation adjacent to but not in contact with chilled meat. The present invention uses sodium alginate and Ca 2+Based on the chelation reaction to encapsulate cinnamaldehyde in the gel beads, a gradient curing strategy is achieved by changing the properties of the coagulation bath and the liquid core, preventing the migration of the embedded substances inside, and enabling the rapid curing of the cinnamaldehyde liquid core in the center to achieve encapsulation. Secondly, through the prepared gel bead wall material, the phosphate ester bond on the serine residue of sodium caseinate contained therein encounters volatile ammonia, and dephosphorylation occurs in an alkaline atmosphere, resulting in the hydrolysis and cleavage of the phosphate ester bond, affecting its membrane cross-linking structure and stability. Eventually, the porosity of the gel beads increases, enabling the cinnamaldehyde liquid core to overcome the inter-pore resistance and continuously release into the environment, realizing the responsive release of cinnamaldehyde.

[0009] The present invention provides a cinnamaldehyde gel bead with ammonia responsiveness. The gel bead is prepared by emulsifying cinnamaldehyde to form a liquid core containing polysaccharide and a cross-linking agent, then dispersing the liquid core in a hydrophilic material containing sodium caseinate, and finally obtaining it through a cross-linking reaction.

[0010] In one embodiment of the present invention, the polysaccharide is one or more of chitosan, carboxymethyl chitosan, xanthan gum.

[0011] In one embodiment of the present invention, the cross-linking agent is a physical cross-linking agent, which is a cationic polymer or at least one metal salt of Ca 2 + , Cu 2+ or the like.

[0012] In one embodiment of the present invention, the hydrophilic material is a degradable high molecular polymer.

[0013] In one embodiment of the present invention, the hydrophilic material is one or more of sodium alginate, cellulose, gelatin, agar.

[0014] The present invention provides a preparation method of a cinnamaldehyde gel bead with ammonia responsiveness, including the following steps:

[0015] (1) Disperse the polysaccharide in deionized water, adjust the pH to 5 - 6 to fully dissolve, add the cross-linking agent to obtain a mixed solution, then add cinnamaldehyde, and perform ultrasonic emulsification for 1 - 5 min to obtain a liquid core;

[0016] (2) Disperse sodium alginate in deionized water, stir to dissolve, and then add sodium caseinate and mix evenly to obtain a coagulation bath;

[0017] (3) Drop the liquid core into the coagulation bath, and finally obtain the ammonia-responsive cinnamaldehyde gel bead after washing.

[0018] In one embodiment of the present invention, in step (1), in the liquid core, the mass fractions of the polysaccharide, the cross-linking agent, and cinnamaldehyde are 1 - 8%, 0.5 - 6%, and 0.5 - 30% respectively.

[0019] In an embodiment of the present invention, in step (2), in the coagulation bath, the mass fractions of sodium alginate and sodium caseinate are 0.1-5% and 0.1-5% respectively.

[0020] In an embodiment of the present invention, in step (3), the mass ratio of the liquid core to the coagulation bath is 1:5-125.

[0021] In an embodiment of the present invention, in step (3), the liquid core is adjusted to a rotation speed of 0.5-10 mL / min by a peristaltic pump and is dropped into the coagulation bath obtained in step (2) through a silica gel tube with an inner diameter of 0.1-0.8 mm.

[0022] The present invention also provides the application of the above-mentioned ammonia-responsive cinnamaldehyde gel beads in the preservation and antibacterial of chilled meat.

[0023] [Beneficial effects]

[0024] (1) The method of the present invention is simple, efficient, and uses natural marine element extracts such as chitosan and other crustaceans, and polymer degradable substances such as sodium alginate. At present, most chitosans act as wall materials, while in the present invention, chitosan is added to the liquid core instead of the wall material, aiming to regulate the viscosity of the liquid core, change the migration trajectory of cinnamaldehyde essential oil inside, and finally achieve the characteristics of improving the explosive sudden release and continuous high-level release of cinnamaldehyde. In addition, the release behavior of internal substances can be regulated by changing the coagulation bath and the core liquid. By adjusting the ratio of the composite material of the liquid core and the coagulation bath, the crosslinking degree of the wall material of the casein gel beads can be adjusted, thereby regulating the response performance of the ammonia-responsive cinnamaldehyde gel beads, controlling the release rate of cinnamaldehyde, and finally regulating the preservation effect and prolonging the spoilage of chilled meat. Therefore, the method of the present invention has potential in preserving chilled food and upgrading cold chain logistics.

[0025] (2) At present, there are few studies and reports on the controllable non-contact preservation of chilled meat. Sodium caseinate is added as an emulsifier to the liquid core, but there are often problems such as poor compatibility with the liquid core leading to modification failure. The present invention is the first to add sodium caseinate to the wall material to prepare ammonia-responsive cinnamaldehyde gel beads to achieve amine (alkaline) response performance.

[0026] (3) In the present invention, the emulsified cinnamaldehyde essential oil containing calcium ions is dropped into the sodium alginate coagulation bath in the form of droplets to form solid cinnamaldehyde gel beads. With the casein attached to the composite wall material of the synthesized gel beads, the phosphate ester bond on the serine residue of sodium caseinate contained therein encounters volatile ammonia, and dephosphorylation occurs in an alkaline atmosphere, resulting in hydrolysis and cleavage of the phosphate ester bond, affecting its membrane cross-linking structure and stability, controlling the porosity of the gel beads and the tension of the internal liquid core, and realizing the function of responding to alkaline gases. Through the non-contact response release method, long-term high-level release is achieved, reducing the pollution of cinnamaldehyde essential oil to chilled meat during preservation and its adverse effects on the sensory properties.

[0027] (4) The preparation method of the present invention is carried out at room temperature, is simple and easy to implement, and does not require the addition of materials such as activators, stabilizers, and thickeners. It is safer, more efficient for chilled fresh preservation, and can improve the acceptance of consumers. By adjusting the number of added gel beads, the release effect of the explosive sudden release of cinnamaldehyde can be improved, and a headspace antibacterial atmosphere can be achieved in the preservation box as soon as possible after the response release, expanding its application scope and value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the appearance diagram of the ammonia-responsive cinnamaldehyde gel beads in Examples 1-4 of the present invention;

[0029] Figure 2 It is the micrograph of the liquid core of the gel beads prepared in Comparative Example 1 of the present invention;

[0030] Figure 3 It is the gel bead diagram prepared in Comparative Example 2 of the present invention;

[0031] Figure 4 It is the gel bead and cortical scanning electron micrograph prepared in Comparative Example 3 of the present invention;

[0032] Figure 5 It is the gel bead diagram prepared in Comparative Example 4 of the present invention;

[0033] Figure 6 It is the release curve of cinnamaldehyde in the gel beads in Examples 1 and 5 of the present invention;

[0034] Figure 7 It is the application schematic diagram of the ammonia-responsive cinnamaldehyde gel beads of the present invention;

[0035] Figure 8 It is the scanning electron micrograph of the cortex of the gel beads in Example 1 of the present invention;

[0036] Figure 9 It is the release curve of the ammonia-responsive cinnamaldehyde gel beads prepared in Example 1 of the present invention;

[0037] Figure 10Effect diagram of the storage effect of the gel beads on chilled meat in Example 1 of the present invention;

[0038] Figure 11 Colony count diagram of chilled meat at different times during the storage of gel beads in Example 1 of the present invention;

[0039] Figure 12 Bacteriostatic effect diagram of gel beads in the storage of chilled meat in Example 1 of the present invention. Detailed implementation manners

[0040] The following are descriptions of the preferred embodiments of the present invention. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0041] The detection methods involved in the following embodiments:

[0042] Cinnamaldehyde loading of the ammonia-responsive gel beads:

[0043] The detection method for the cinnamaldehyde loading is as follows: Using ultraviolet spectrophotometry, detect the absorbance value of cinnamaldehyde at 286 nm, substitute it into the cinnamaldehyde standard curve, and calculate the cinnamaldehyde content.

[0044] Cinnamaldehyde standard curve: y = 0.1451x + 0.011R 2 = 0.9933

[0045] Where x is the absorbance value and y is the cinnamaldehyde content (μg / mL)

[0046] Calculation method: Cinnamaldehyde loading (mg / g) = cinnamaldehyde content / mass of gel beads.

[0047] The detection and calculation method for the release rate is as follows:

[0048] Detection method: Sampling the gel beads at 0 d, 1 d, 3 d, 5 d, 7 d, and 9 d respectively. First, weigh the cinnamaldehyde gel beads, break them, take the inner core and place it in a centrifuge tube, add 4 g of ethanol, ultrasonically break and extract for 10 min, centrifuge at 10000 rpm at high speed. After centrifugation, take the supernatant, dilute it, and measure its absorbance value at 286 nm. Substitute it into the cinnamaldehyde standard curve to calculate the cinnamaldehyde content;

[0049] The total release rate of cinnamaldehyde is measured by the endpoint method. Calculation method: Total release rate of cinnamaldehyde = 1 - (cinnamaldehyde loading on the nth day / cinnamaldehyde loading on the 0th day);

[0050] The release curve of cinnamaldehyde can be fitted by the first-order release kinetics: Q% = 1 - e -kt , and the k value is obtained.

[0051] Where Q% is the percentage of cinnamaldehyde released at time t and k is the release rate constant.

[0052] Q% = Content of cinnamaldehyde measured at the sampling time point / Content of cinnamaldehyde measured at the initial point.

[0053] Example 1: Preparation of cinnamaldehyde gel beads with ammonia-responsive properties

[0054] Specifically, it includes the following steps:

[0055] (1) Preparation of liquid core:

[0056] Weigh 0.5 g of chitosan powder and disperse it in ultrapure water at a material-liquid ratio of 1:50 (g / mL). Adjust the pH value to 5.0 with 1 mol / L glacial acetic acid solution, and stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to unfold the chitosan chains. Subsequently, weigh 0.5 g of CaCl2 and disperse it in the solution, and continue to stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min). Then, add cinnamaldehyde to the solution at a material-liquid ratio of 1:20 (g / mL), and disperse it at high speed for 3 min at 12,000 rpm using a high-speed shear machine to fully swell and dissolve. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After the ultrasonic treatment, obtain a 5% cinnamaldehyde emulsion as the liquid core of the gel beads.

[0057] (2) Preparation of coagulation bath

[0058] Weigh 5 g of sodium alginate powder and disperse it in ultrapure water at a material-liquid ratio of 1:100 (g / mL), and stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate. Subsequently, weigh 2.5 g of sodium caseinate and add it to the solution, and stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to obtain a coagulation bath, where the concentration of sodium alginate is 1% and the concentration of sodium caseinate is 0.5%.

[0059] (3) Encapsulation of gel beads

[0060] Adjust the flow rate of the peristaltic pump to 6 mL / min, and drop the cinnamaldehyde emulsion into the stirred coagulation bath drop by drop through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to 1 min, let it stand and react for 1 min, then filter it through a nylon mesh and rinse it 3 times with distilled water to obtain cinnamaldehyde gel beads.

[0061] Example 2: Preparation of cinnamaldehyde gel beads with ammonia-responsive properties

[0062] Specifically, it includes the following steps:

[0063] (1) Preparation of liquid core:

[0064] Weigh 0.5 g of chitosan powder and disperse it in ultrapure water at a solid-liquid ratio of 1:50 (g / mL). Adjust the pH value to 5.0 with 1 mol / L glacial acetic acid solution and stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to unfold the chitosan chains. Then weigh 0.5 g of CaCl₂ and disperse it in the solution, and continue to stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min). Subsequently, add cinnamaldehyde to the solution at a solid-liquid ratio of 1:20 (g / mL), and disperse it at a high speed for 3 min at 12,000 rpm using a high-speed shear machine to fully swell and dissolve. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After the ultrasonic treatment, a 5% cinnamaldehyde emulsion is obtained as the liquid core of the gel beads.

[0065] (2) Preparation of the coagulation bath

[0066] Weigh 5 g of sodium alginate powder and disperse it in ultrapure water at a solid-liquid ratio of 1:100 (g / mL). Stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate. Then weigh 0.5 g of agar and 2.5 g of sodium caseinate and add them to the solution. Heat it to 60 °C using a water bath and stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to obtain the coagulation bath, where the concentration of sodium alginate is 1% and the concentration of sodium caseinate is 0.5%.

[0067] (3) Encapsulation of the gel beads

[0068] Adjust the flow rate of the peristaltic pump to 6 mL / min, and drop the cinnamaldehyde emulsion into the stirring coagulation bath drop by drop through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to 1 min, let it stand and react for 1 min, then filter it through a nylon mesh and rinse the coagulation bath 3 times with distilled water to obtain cinnamaldehyde gel beads.

[0069] Example 3: Preparation of ammonia-responsive cinnamaldehyde gel beads

[0070] (1) Preparation of the liquid core:

[0071] Weigh 0.5 g of carboxymethyl chitosan powder, disperse it in ultrapure water at a solid-liquid ratio of 1:50 (g / mL), adjust the pH to 5, and stir well (rotation speed: 660 rpm, stirring time: 30 min) to unfold the carboxymethyl chitosan chains. Then weigh 0.5 g of CaCl2 and disperse it in the solution, and continue to stir well (rotation speed: 660 rpm, stirring time: 30 min). Subsequently, add cinnamaldehyde to the solution at a solid-liquid ratio of 1:20, and disperse it at a high speed of 12000 rpm using a high-speed shear machine for 3 min to fully swell and dissolve. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After the ultrasonic treatment, a 5% cinnamaldehyde emulsion is obtained as the liquid core of the gel beads.

[0072] (2) Preparation of coagulation bath

[0073] Weigh 5 g of sodium alginate powder, disperse it in ultrapure water at a solid-liquid ratio of 1:100 (g / mL), and stir well (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate. Then weigh 2.5 g of sodium caseinate and add it to the solution. After stirring well (rotation speed: 660 rpm, stirring time: 30 min), a coagulation bath is obtained, where the concentration of sodium alginate is 1% and the concentration of sodium caseinate is 0.5%.

[0074] (3) Encapsulation of gel beads

[0075] Adjust the flow rate of the peristaltic pump to 6 mL / min, and drop the cinnamaldehyde emulsion into the stirred coagulation bath drop by drop through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to 1 min, let it stand and react for 1 min, then filter it through a nylon mesh and rinse the coagulation bath with distilled water 3 times to obtain cinnamaldehyde gel beads.

[0076] Example 4: Preparation of cinnamaldehyde gel beads with ammonia-responsive properties

[0077] (1) Preparation of liquid core:

[0078] Weigh 0.5 g of xanthan gum powder, disperse it in ultrapure water at a solid-liquid ratio of 1:50 (g / mL), adjust the pH to 5, then weigh 0.5 g of CaCl2 and disperse it in the solution, and continue to stir well (rotation speed: 660 rpm, stirring time: 30 min). Subsequently, add cinnamaldehyde to the solution at a solid-liquid ratio of 1:20, and disperse it at a high speed of 12000 rpm using a high-speed shear machine for 3 min to fully swell and dissolve. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After the ultrasonic treatment, a 5% cinnamaldehyde emulsion is obtained as the liquid core of the gel beads.

[0079] (2) Preparation of coagulation bath

[0080] Weigh 5 g of sodium alginate powder and disperse it in ultrapure water at a solid-liquid ratio of 1:100 (g / mL). Stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate. Then weigh 2.5 g of sodium caseinate and add it to the solution. After stirring thoroughly (rotation speed: 660 rpm, stirring time: 30 min), a coagulation bath is obtained, where the concentration of sodium alginate is 1% and the concentration of sodium caseinate is 0.5%.

[0081] (3) Encapsulating the gel beads

[0082] Adjust the peristaltic pump flow rate to 6 mL / min. Dropwise add the cinnamaldehyde emulsion into the stirred coagulation bath through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to be 1 min, let it stand and react for 1 min, then filter through a nylon mesh and rinse the coagulation bath with distilled water 3 times to obtain cinnamaldehyde gel beads.

[0083] Comparative Example 1

[0084] (1) Preparation of the liquid core

[0085] Weigh 0.5 g of chitosan powder and disperse it in ultrapure water at a solid-liquid ratio of 1:50 (g / mL). Adjust the pH value to 5.0 with 1 mol / L glacial acetic acid solution. Stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to unfold the chitosan chains. Then weigh 0.5 g of CaCl2 and disperse it in the solution. Continue to stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min). Then add cinnamaldehyde to the solution at a solid-liquid ratio of 1:20, and weigh sodium caseinate and add it to the solution at a material ratio of 1:200. Use a high-speed shearer to disperse it at 12,000 rpm for 3 min to fully swell and dissolve. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After the ultrasonic treatment, a 5% cinnamaldehyde and 0.5% sodium caseinate emulsion is obtained as the liquid core of the gel beads.

[0086] (2) Preparation of the coagulation bath

[0087] Weigh 5 g of sodium alginate powder and disperse it in ultrapure water at a solid-liquid ratio of 1:100 (g / mL). Stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate to obtain a coagulation bath, where the concentration of sodium alginate is 1%.

[0088] (3) Encapsulating the gel beads

[0089] Adjust the flow rate of the peristaltic pump to 6 mL / min, and drop the cinnamaldehyde emulsion into the stirred coagulation bath drop by drop through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to 1 min, let it stand and react for 1 min, then filter through a nylon mesh and rinse 3 times with distilled water to obtain cinnamaldehyde gel beads.

[0090] The results are as Figure 2 shown. Sodium caseinate cannot be fully emulsified in the liquid core and is only dispersed large particles. The gel beads formed by dropping do not have special response properties.

[0091] Comparative Example 2

[0092] (1) Weigh 0.5 g of chitosan powder, disperse it in ultrapure water at a solid-liquid ratio of 1:50 (g / mL), adjust the pH value to 5.0 with 1 mol / L glacial acetic acid solution, and stir well (rotation speed: 660 rpm, stirring time: 30 min) to unfold the chitosan chains. Then, add cinnamaldehyde to the solution at a solid-liquid ratio of 1:20, and disperse it at high speed for 3 min at 12,000 rpm using a high-speed shear machine to fully swell and dissolve. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After ultrasonic treatment, obtain a 5% cinnamaldehyde emulsion as the liquid core of the gel beads.

[0093] (2) Preparation of the coagulation bath

[0094] Weigh 5 g of sodium alginate powder, disperse it in ultrapure water at a solid-liquid ratio of 1:100 (g / mL), and stir well (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate. Then, weigh 2.5 g of sodium caseinate and add it to the solution, and stir well (rotation speed: 660 rpm, stirring time: 30 min) to obtain a coagulation bath, where the concentration of sodium alginate is 1% and the concentration of sodium caseinate is 0.5%.

[0095] (3) Encapsulation of gel beads

[0096] Adjust the flow rate of the peristaltic pump to 6 mL / min, and drop the cinnamaldehyde emulsion into the stirred coagulation bath drop by drop through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to 1 min, let it stand and react for 1 min, then filter through a nylon mesh and rinse 3 times with distilled water to obtain cinnamaldehyde gel beads.

[0097] The results are as Figure 3 shown. The gel beads with only chitosan as the wall material cannot crosslink and form a shape, flocculate and aggregate into filaments, and do not have special response properties.

[0098] Comparative Example 3

[0099] (1) Preparation of the liquid core:

[0100] Weigh 0.5 g of chitosan powder and disperse it in ultrapure water at a solid-liquid ratio of 1:50 (g / mL). Adjust the pH value to 5.0 with 1 mol / L glacial acetic acid solution, and stir well (rotation speed: 660 rpm, stirring time: 30 min) to unfold the chitosan chains. Subsequently, weigh 0.5 g of CaCl2 and disperse it in the solution, and continue to stir well (rotation speed: 660 rpm, stirring time: 30 min). Then, add cinnamaldehyde to the solution at a solid-liquid ratio of 1:20, and disperse it at a high speed of 12,000 rpm with a high-speed shear mixer for 3 min to fully swell and dissolve. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After the ultrasonic treatment, a 5% cinnamaldehyde emulsion is obtained as the liquid core of the gel beads.

[0101] (2) Preparation of the coagulation bath

[0102] Weigh 5 g of sodium alginate powder and disperse it in ultrapure water at a solid-liquid ratio of 1:100 (g / mL), and stir well (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate to obtain the coagulation bath, where the concentration of sodium alginate is 1%.

[0103] (3) Encapsulation of the gel beads

[0104] Adjust the flow rate of the peristaltic pump to 6 mL / min, and drop the cinnamaldehyde emulsion into the stirred coagulation bath drop by drop through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to 1 min, let it stand and react for 1 min, then filter it through a nylon mesh and rinse it 3 times with distilled water to obtain cinnamaldehyde gel beads.

[0105] The results are as Figure 4 shown. The gel beads formed by dropping have a complete shape, but the wall material cannot form a morphology with sodium caseinate particles embedded, and it does not have special response performance.

[0106] Comparative Example 4

[0107] (1) Preparation of the liquid core:

[0108] Weigh 0.5 g of chitosan powder and disperse it in ultrapure water at a solid-liquid ratio of 1:50 (g / mL). Adjust the pH value to 6.5 with 1 mol / L glacial acetic acid solution, and stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to unfold the chitosan chains. Then weigh 0.5 g of CaCl₂ and disperse it in the solution, and continue to stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min). Subsequently, add cinnamaldehyde dropwise to the solution at a solid-liquid ratio of 1:20, and disperse it at high speed for 3 min with a high-speed shearer at 12,000 rpm to fully swell and dissolve. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After the ultrasonic treatment, a 5% cinnamaldehyde emulsion is obtained as the liquid core of the gel beads.

[0109] (2) Preparation of the coagulation bath

[0110] Weigh 5 g of sodium alginate powder and disperse it in ultrapure water at a solid-liquid ratio of 1:100 (g / mL), and stir thoroughly (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate. Then weigh 2.5 g of sodium caseinate and add it to the solution. After stirring thoroughly (rotation speed: 660 rpm, stirring time: 30 min), a coagulation bath is obtained, in which the concentration of sodium alginate is 1% and the concentration of sodium caseinate is 0.5%.

[0111] (3) Encapsulation of the gel beads

[0112] Adjust the flow rate of the peristaltic pump to 6 mL / min, and drop the cinnamaldehyde emulsion into the stirred coagulation bath drop by drop through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to 1 min, let it stand and react for 1 min, then filter it through a nylon mesh and rinse it 3 times with distilled water to obtain cinnamaldehyde gel beads.

[0113] The results are as Figure 5 shown. When the pH value is too high, the chitosan gelation is severe. Finally, the formed gel beads are in a block shape, without a complete spherical shape and do not have special response performance.

[0114] Example 5

[0115] The preparation method is the same as that of Example 1, and the difference is only that: change the content of sodium caseinate, which specifically includes the following steps:

[0116] (1) Preparation of the liquid core:

[0117] Weigh 0.5 g of chitosan powder and disperse it in ultrapure water at a solid-liquid ratio of 1:50 (g / mL). Adjust the pH value to 5.0 with 1 mol / L glacial acetic acid solution, and stir vigorously (rotation speed: 660 rpm, stirring time: 30 min) to unfold the chitosan chains. Then weigh 0.5 g of CaCl2 and disperse it in the solution, and continue to stir vigorously (rotation speed: 660 rpm, stirring time: 30 min). Subsequently, add cinnamaldehyde to the solution at a solid-liquid ratio of 1:20, and disperse it at a high speed of 12,000 rpm for 3 min with a high-speed shear machine to achieve full swelling and dissolution. Place the obtained solution in an ice-water bath and ultrasonically crush and emulsify it. The ultrasonic conditions are: amplitude 40 μm, stop for 2 s after every 5 s of ultrasonic treatment, and the total ultrasonic time is 2 min. After the ultrasonic treatment, a 5% cinnamaldehyde emulsion is obtained as the liquid core of the gel beads.

[0118] (2) Preparation of the coagulation bath

[0119] Weigh 5 g of sodium alginate powder and disperse it in ultrapure water at a solid-liquid ratio of 1:100 (g / mL), and stir vigorously (rotation speed: 660 rpm, stirring time: 30 min) to fully swell the sodium alginate. Then weigh sodium caseinate and add it to the solution, and stir vigorously (rotation speed: 660 rpm, stirring time: 30 min) to obtain the coagulation bath, where the concentration of sodium alginate is 1%, and the concentrations of sodium caseinate are kept at 1% and 1.5% respectively.

[0120] (3) Encapsulation of gel beads

[0121] Adjust the flow rate of the peristaltic pump to 6 mL / min, and drop the cinnamaldehyde emulsion into the stirred coagulation bath drop by drop through a silica gel tube with an inner diameter of 0.2 mm. Control the dropping time to 1 min, let it stand and react for 1 min, then filter it through a nylon mesh and rinse it 3 times with distilled water to obtain cinnamaldehyde gel beads with the content of sodium caseinate in the wall material being 1% and 1.5% respectively.

[0122] Measure the cinnamaldehyde loading capacity, release rate and k value of the gel beads obtained in Example 1 and Example 5 respectively. The results are shown in Table 1 and Figure 6 (left for storage, right for preservation) as follows:

[0123] Table 1 Cinnamaldehyde loading capacity, release rate and response performance of sodium caseinate with different contents

[0124]

[0125] The results show that:

[0126] (1) When the content of sodium caseinate is 0.5%, the cinnamaldehyde loading capacity is relatively high, reaching 11.49 ± 1.2 mg / g, the cinnamaldehyde release rate is fast, and its k value is 1.8474 ± 0.0017.

[0127] (2) When the sodium caseinate content is 0%, the cinnamaldehyde loading is relatively high, reaching 10.22 ± 0.3 mg / g. The release rate of cinnamaldehyde is fast, and its k value is 0.6659 ± 0.0094.

[0128] (3) When the sodium caseinate content is 1%, the cinnamaldehyde loading is relatively high, reaching 15.38 ± 1.0 mg / g. The release rate of cinnamaldehyde is fast, and its k value is 0.2537 ± 0.0059.

[0129] (4) When the sodium caseinate content is 1.5%, the cinnamaldehyde loading is relatively high, reaching 22.93 ± 0.7 mg / g. The release rate of cinnamaldehyde is fast, and its k value is 0.3357 ± 0.0017.

[0130] (5) As can be seen from Table 1, when the sodium caseinate contents are 0.5%, 1%, and 1.5% respectively, the percentages of the total release amounts are 64.7%, 85.6%, and 89.4% respectively. When applied to preservation, their total release rates are increased to 85.5%, 88.5%, and 92.5% respectively. The release profiles of the gel beads with three sodium caseinate ratios show that the higher the sodium caseinate content, the higher its loading and the higher the total release rate. However, the addition amount of sodium caseinate is not the more the better. When the addition amount of sodium caseinate is greater than 0.5%, the k value decreases, indicating that its release rate decreases. The difference between the total release rates of the gel beads during ordinary storage and when applied to preservation reflects the response performance to biogenic amines. By comparison, we found that when the addition amount of sodium caseinate is greater than 0.5%, the difference in its total release rate significantly decreases, indicating that its response effect to biogenic amines will be reduced.

[0131] During use, only the gel beads prepared according to the above method need to be placed adjacent but not in contact in an environment full of biogenic amines (for example, when cold fresh meat is stored, volatile biogenic amines are produced as bacteria decompose muscle proteins and fats) (such as Figure 7 ) to trigger the release of cinnamaldehyde by the response of the wall material.

[0132] Figure 8 It is the scanning electron micrograph of the cortex of the gel beads (sodium caseinate content is 0.5%) in Example 1 during the application of cold fresh meat preservation over time. As Figure 8 shown, the pores of the gel beads change from dense to loose. Since the wall material comes into contact with the biogenic amines volatilized during the preservation of meat products, the serine residues of sodium caseinate on it respond and expand, promoting the release of the internal cinnamaldehyde essential oil.

[0133] Take the response release test of the ammonia-responsive cinnamaldehyde gel beads prepared in Example 1 and test them, and make a release curve. Place the gel beads in an environment of 10% NH3 and 90% N2, as Figure 9As shown, its release time can reach 11 days, and the release rate remains in a high-concentration atmosphere with a cumulative release rate of up to 90% compared to the control air environment.

[0134] Take the gel beads prepared in Example 1 and place them in a chilled fresh meat packaging box for effect evaluation. The results are as Figure 10 shown. It can be seen that compared with the control group without gel beads, the group with gel beads has a better color protection effect on chilled fresh meat, delaying the phenomenon of surface roughness and stickiness, indicating that the ammonia-triggered release gel beads have a good fresh-keeping effect on chilled fresh meat.

[0135] Refer to the national standard (GB4789.2–2016) and use the plate counting method to count the total number of colonies in chilled fresh meat at different times. Figure 11 For the comparison of the number of colonies between the control group and the gel bead group on the 5th day, the number of colonies of the gel beads is significantly less than that of the chilled fresh meat group. Figure 12 For the total number of colonies in chilled fresh meat during the 9-day storage period, by the 5th day, the control group had reached the spoilage standard (TNC≥7lgCFU / g), while the gel bead group was still in a fresh state, demonstrating the good antibacterial effect of the gel beads.

[0136] The embodiments provided above are not intended to limit the scope covered by the present invention, nor are the described steps intended to limit their execution order. Obvious improvements made by those skilled in the art in combination with the existing common general knowledge also fall within the protection scope defined by the claims of the present invention.

Claims

1. A cinnamaldehyde gel bead with ammonia responsiveness, characterized in that, The gel beads are prepared by emulsifying cinnamaldehyde to form a liquid core containing polysaccharide and crosslinking agent, then dispersing the liquid core in a hydrophilic group material containing sodium caseinate, and finally carrying out a crosslinking reaction.

2. The ammonia-responsive cinnamaldehyde gel beads according to claim 1, wherein The polysaccharide is one or more of chitosan, carboxymethyl chitosan, xanthan gum.

3. The ammonia-responsive cinnamaldehyde gel beads according to claim 1, wherein The crosslinking agent is a physical crosslinking agent, which is a cationic polymer or Ca 2+ , Cu 2+ At least one metal salt.

4. The ammonia-responsive cinnamaldehyde gel beads according to claim 1, wherein The hydrophilic group material is one or more of sodium alginate, cellulose, gelatin, agar.

5. The preparation method of the cinnamaldehyde gel beads with ammonia responsiveness according to any one of claims 1 to 4, characterized in that, It includes the following steps: (1) Disperse the polysaccharide in deionized water, adjust the pH to 5 - 6 and dissolve it sufficiently, add the crosslinking agent to obtain a mixed solution, then add cinnamaldehyde and carry out ultrasonic emulsification to obtain a liquid core; (2) Disperse sodium alginate in deionized water, stir to dissolve it, then add sodium caseinate and mix evenly to obtain a coagulation bath; (3) Drop the liquid core into the coagulation bath, and finally obtain ammonia-responsive cinnamaldehyde gel beads after washing.

6. The method according to claim 5, characterized in that, In step (1), in the liquid core, the mass fractions of the polysaccharide, crosslinking agent, and cinnamaldehyde are 1 - 8%, 0.5 - 6%, and 0.5 - 30% respectively.

7. The method according to claim 5, characterized in that, In step (2), in the coagulation bath, the mass fractions of sodium alginate and sodium caseinate are 0.1 - 5% and 0.1 - 5% respectively.

8. The method according to claim 5, wherein In step (3), the mass ratio of the liquid core to the coagulation bath is 1:5 - 125.

9. The method according to claim 5, wherein In step (3), adjust the rotation speed of the liquid core with a peristaltic pump to 0.5 - 10 mL / min, and drop it into the obtained coagulation bath through a silica gel tube with an inner diameter of 0.1 - 0.8 mm.

10. Application of the ammonia-responsive cinnamaldehyde gel beads according to any one of claims 1 - 4 in the fresh-keeping and antibacterial of chilled meat.

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