Preparation method and application of a perilla alcohol extract composite edible emulsion

Abstract

The present invention discloses a preparation method and application of a composite edible emulsion of perilla alcohol extract, focusing on its good antibacterial, antioxidant, washability (10s) and preservation properties. Using zein and chitosan as encapsulation carriers, a multifunctional edible emulsion was prepared, which contained lysozyme, EGCG and perilla alcohol extract (Z / C-LEP) for the preservation of active foods. After storage for one month, it still had a high polyphenol content. The good sustained-release effect at room temperature and the antibacterial and antioxidant properties enhanced by the bidirectional synergistic mechanism enable the edible emulsion to have a better preservation effect on fruits and vegetables. As a natural polymer, Z / C-LEP is non-toxic, edible, biodegradable and environmentally friendly, and is expected to be effectively applied in the preservation of fruits and vegetables.

Description

Technical Field

[0001] The present invention relates to the technical field of edible emulsion preparation, in particular to a preparation method and application of a Z / C-LEP edible emulsion. Background Art

[0002] Major global challenges, such as famine, public health emergencies, and rapid climate change, are closely linked to the severe food waste worldwide. This problem is particularly acute for fresh produce, such as fruits and vegetables, where approximately 40-50% of field-produced crops are wasted annually. In recent years, the prepared meal industry has gradually emerged with development. However, as agriculture has evolved, the storage of various fruits and vegetables has become a major constraint to the industry's growth. Numerous factors contribute to the spoilage of fresh food, primarily dehydration, respiratory metabolism, and microbial growth. Appropriately applying a thin, edible coating to fruits and other agricultural products to extend their shelf life is an attractive option for alleviating the spoilage challenge.

[0003] In recent years, natural materials such as polysaccharides, proteins, lipids, chitosan, and alginate have been increasingly used for postharvest preservation of fruits and vegetables. Zein, an edible alcoholic protein, has been used as a drug carrier and dietary supplement due to its good biodegradability and biocompatibility. However, studies have shown that nanoparticles prepared solely from zein, without any modification, tend to aggregate and exhibit a bursting effect (the embedded material is rapidly released from the particle within a short period of time, indicating low absorption capacity). To overcome these obstacles, zein particles can be encapsulated with polysaccharides as colloidal stabilizers. The resulting zein particles exhibit a positive effect on the bursting effect during digestion. Chitosan (CS), a cationic polysaccharide, has attracted considerable interest due to its great potential in food processing. Studies have shown that CS is an excellent stabilizer for zein nanoparticles, providing steric resistance and electrostatic stabilization, effectively preventing zein aggregation under neutral conditions and after drying. Therefore, zein and chitosan can be prepared into nanoparticles and easily formulated into edible emulsions for fruit and vegetable preservation.

[0004] Natural polymers have poor preservation effects due to poor or no antimicrobial activity, and all developed materials do not exhibit unique properties when used alone. Therefore, it is often necessary to add antimicrobial active ingredients to improve the antimicrobial activity of natural polymer materials. Chemical preservatives, such as fungicides, pesticides, and inorganic salts, are widely used in the food industry due to their high antimicrobial activity against microorganisms. However, the addition of chemical agents has potential hazards to the human body. Therefore, due to the increasing concern about food safety and human health, preservatives extracted from natural products are becoming increasingly popular. Recently, researchers have paid extensive attention to the use of natural products with antimicrobial activity to replace chemical fungicides in food preservation, such as phenols, chitin, and plant essential oils.

[0005] Perilla leaves have been identified as having high levels of volatile compounds and are primarily cultivated in Asian countries. Perilla is an edible vegetable used in salads, sushi, and soups, as well as pickled and used as a garnish. Perilla leaves have traditionally been used for their antioxidant, antidiabetic, antiallergic, antimicrobial, antitumor, and anticancer properties due to their phenolic compounds, rosmarinic acid, anthocyanins, essential oils, vitamins, and minerals. However, the effects of single natural product extracts are limited, and synergistic effects can be induced by combining them with other substances. Epigallocatechin-3-gallate (EGG), isolated from the leaves of Camellia sinensis (green tea), is considered the most abundant polyphenol in this plant and exhibits various therapeutic properties, such as strong chelating and antioxidant activities. However, polyphenols are easily oxidized at relatively high temperatures, oxygen concentrations, and pH values. Furthermore, polyphenols are less effective against Gram-positive bacteria because their cell wall polysaccharides significantly hinder permeability. Lysozyme (Lys), a cellular enzyme and small cationic protein, can damage or kill bacteria by catalyzing the hydrolysis of β-1,4-linkages between N-acetylaminocarbamate and N-acetyl-D-glucosamine residues in bacterial cell walls. Lysozyme has demonstrated active antimicrobial activity against Gram-positive bacteria. The addition of lysozyme not only enhances antimicrobial activity but also serves as an effective delivery vehicle for natural antioxidants.

[0006] Therefore, the present invention uses zein and chitosan as encapsulation carriers to prepare a multifunctional edible emulsion loaded with lysozyme, EGCG, and perilla frutescens ethanol extract for fruit and vegetable preservation. The addition of lysozyme enhances the antibacterial activity of the perilla frutescens ethanol extract against Gram-positive pathogens. The further addition of EGCG enhances the antioxidant properties of the perilla frutescens ethanol extract. Furthermore, the sustained release properties of this edible emulsion at room temperature enable the prepared multifunctional edible emulsion to have good potential for preservation in fruit and vegetable storage. Summary of the Invention

[0007] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a preparation method and application of an edible emulsion of Z / C-LEP.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The invention discloses an edible emulsion of Z / C-LEP. The emulsion takes a mixed solution (Z / C) of zein and chitosan as a base, and lysozyme, EGCG and perilla frutescens ethanol extract as fillers and is added into the mixed solution of zein and chitosan.

[0010] A method for preparing a Z / C-LEP edible emulsion comprises the following steps:

[0011] (1) Dispersing zein in a 70% ethanol aqueous solution and magnetically stirring for 10 minutes to obtain a zein dispersion;

[0012] (2) Dispersing chitosan in a 1% acetic acid aqueous solution and magnetically stirring for 10 min to obtain a chitosan dispersion;

[0013] (3) mixing the zein dispersion and chitosan dispersion obtained in step (1) and step (2), ultrasonically treating at 450W for 5 minutes, placing in a 75°C water bath for 30 minutes, and finally cooling at 4°C to terminate the reaction, thereby obtaining a mixed solution of zein and chitosan (Z / C);

[0014] (4) adding 0.1 g / L lysozyme to the Z / C solution obtained in step (3) and magnetically stirring for 5 min to obtain a Z / CL dispersion;

[0015] (5) adding 1 g / L EGCG to the Z / CL dispersion obtained in step (4) and magnetically stirring for 5 min to obtain a Z / C-LE dispersion;

[0016] (6) adding 150 mg / L of perilla frutescens ethanol extract to the Z / C-LE dispersion obtained in step (5), and magnetically stirring for 5 min to obtain a Z / C-LEP dispersion;

[0017] (7) 1 g / L EGCG and 150 mg / L perilla frutescens ethanol extract were added to the Z / C solution obtained in step (3), and magnetic stirring was performed for 5 min to obtain a Z / C-EP dispersion;

[0018] (8) The solutions described in steps (3) to (6) were stirred at 60° C., the heated solutions were poured into a Teflon box, and dried to obtain different types of edible emulsion antibacterial film materials for subsequent testing.

[0019] Preferably, in step (3), the mass ratio of zein to chitosan is (1-10:1).

[0020] Preferably, in step (4), the mass ratio of lysozyme to Z / C is (1-10:800).

[0021] Preferably, in step (5), the mass ratio of EGCG to Z / CL is (1-5:800).

[0022] Preferably, in step (6), the mass ratio of the perilla frutescens ethanol extract to Z / C-LE is (1-10:800).

[0023] The edible emulsion is used in the antibacterial treatment of pathogens including Escherichia coli and Staphylococcus aureus.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The edible emulsion of the present invention exhibits excellent sustained-release properties at room temperature and antibacterial and antioxidant properties enhanced by a bidirectional synergistic mechanism. Z / C-LEP edible emulsion has good washability and broad preservation properties for fruits and vegetables, and has potential applications in the field of fruit and vegetable preservation.

[0026] 2. The Z / C-LEP edible emulsion prepared by self-assembly in the present invention is simple to operate and easy to mass produce;

[0027] 3. The Z / C-LEP edible emulsion prepared by the present invention exhibits excellent antibacterial effects against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. It also exhibits significant antibacterial effects against mold in fruits and vegetables. This demonstrates the potential of this edible emulsion in applications such as inhibiting bacterial infections and stimulating food hygiene and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more specifically and intuitively illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0029] Figure 1 SEM (electron microscopy) photos of edible emulsions of Z / C, Z / CL, Z / C-LE, and Z / C-LEP (a); particle size, PDI (b), and Zeta potential (c) of edible emulsions of Z / C, Z / CL, Z / C-EP, Z / C-LE, and Z / C-LEP; FT-IR (d) of Z / C, Z / CL, Z / C-LE, and Z / C-LEP; and UV-Vis (e) of Z / C-EP, Z / C-LE, and Z / C-LEP.

[0030] Figure 2Figure 3 shows the polyphenol content of Z / C-EP, Z / C-LE, and Z / C-LEP after one month of storage (a), the polyphenol release curves of Z / C-EP, Z / C-LE, and Z / C-LEP (b), the nucleic acid leakage (c), antibacterial activity (d), and inhibition zones against Escherichia coli and Staphylococcus aureus (ef) of Z / C, Z / CL, Z / C-LE, and Z / C-LEP.

[0031] Figure 3 The middle part shows the production of LDH (a) and ROS (b) by Z / C, Z / CL, Z / C-LE, and Z / C-LEP against Escherichia coli and Staphylococcus aureus, respectively.

[0032] Figure 4 is the scavenging rate of Z / C, Z / CL, Z / C-LE, and Z / C-LEP on DPPH free radicals;

[0033] Figure 5 The preservation effects of Z / C, Z / CL, Z / C-LE, and Z / C-LEP on strawberries (a), weight loss rate (b), titratable acid content (c), and Vc content (d);

[0034] Figure 6 Cherry tomatoes were selected as a model to illustrate the washability of Z / C-LEP (a) and its wide application in the preservation of fruits and vegetables (b). DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0036] The invention discloses an edible emulsion of Z / C-LEP. The emulsion takes a mixed solution (Z / C) of zein and chitosan as a base, and lysozyme, EGCG and perilla frutescens ethanol extract as fillers and is added into the mixed solution of zein and chitosan.

[0037] A method for preparing an edible emulsion of Z / C-LEP comprises the following steps:

[0038] (1) Preparation of Zein and Chitosan Base Solution:

[0039] Dissolve 0.5 g of zein in 25 mL of 70% ethanol to prepare a 20 g / L zein solution. Dissolve 0.5 g of zein in 25 mL of 1% acetic acid to prepare a 20 g / L chitosan solution. Mix the two in a 1:1 (m:m) ratio. Ultrasonicate at 450 W for 5 minutes, incubate in a 75°C water bath for 30 minutes, and cool to 4°C to terminate the reaction, obtaining a zein and chitosan mixed solution (Z / C).

[0040] (2) Preparation of edible emulsion:

[0041] 0.1 g / L lysozyme was added to Z / C and magnetically stirred for 5 minutes to obtain a mixture of zein, chitosan, and lysozyme (Z / CL). 1 g / L EGCG and 150 mg / L perilla alcohol extract were added in the same manner to obtain Z / C-LE and Z / C-LEP. The mixture without lysozyme was designated Z / C-EP.

[0042] (3) Preparation of edible emulsion film material:

[0043] The film was prepared according to the so-called casting technique. The edible emulsion coating obtained in (2) was cast on a 10×10 cm plastic plate, dried at 60° C., removed from the plastic plate, conditioned at 25° C. and 50% relative humidity (RH) and set aside.

[0044] Characterization and performance study of Z / C-LEP edible emulsion and food preservation test:

[0045] 1. SEM analysis, particle size, potential analysis (attached Figure 1 ):

[0046] The morphologies of Z / C(Ⅰ), Z / CL(Ⅱ), Z / C-LE(Ⅲ) and Z / C-LEP(Ⅳ) prepared in this example were observed and analyzed using a scanning electron microscope (TM300, Japan). The results are shown in the attached figure. Figure 1 (a):

[0047] Figure 1 (a) is a scanning electron microscope photo of the morphology of Z / C, Z / CL, Z / C-LE, and Z / C-LEP in this example. Figure 1 (a) The wrinkle structures of Z / C, Z / CL, Z / C-LE, and Z / C-LEP can be observed, which are layered.

[0048] The particle size, PDI and potential of the emulsion in this example were analyzed using a Zeta potential analyzer (Nano ZS 3690, UK). The potential of the droplet size distribution is a key factor in evaluating the emulsification effect and emulsion stability. The results are shown in the attached Figure 1 (bc):.

[0049] Figure 1 (b) Particle size and polydispersity index of Z / C, Z / CL, Z / C-EP, Z / C-LE, and Z / C-LEP prepared in this example.

[0050] Figure 1(c) is the potential of Z / C, Z / CL, Z / C-EP, Z / C-LE, and Z / C-LEP prepared in this example.

[0051] 2. FT-IR and UV-Vis analysis (attached Figure 1 )

[0052] The functional groups and maximum wavelength absorption peaks of Z / C, Z / CL, Z / C-LE and Z / C-LEP prepared in this example were characterized by Fourier transform infrared spectrometer (Thermo Scientific Nicolet Is5, USA) and UV-Vis (UV1200, China). The results are shown in the attached Figure 1 (de):

[0053] Representative spectra of Z / C, Z / CL, ZC-LE, and Z / C-LEP are shown in Figure 2. Figure 1 d. The wave number peak is about 2934cm -1 It represents the asymmetric stretching vibration of C–H in CH2 and CH3 groups. The peak of the amide band is at 1660 cm -1 was assigned to C=O and CN, indicating that peptide bond vibration stretching occurred. Another peak of the amide band was located at 1423 cm -1 It is attributed to the dominance of C–H deviation vibration. 1033cm -1 The symmetrical COC stretching vibration absorption peak at 1655cm indicates the generation of Z / C. -1 and 1423cm -1 The characteristic peaks at 2920 cm correspond to the absorption peaks of amide I (C=O stretching vibration) and amide II (NH bending vibration) of lysozyme. -1 The absorption peak at 1276cm is the -CH2 stretching vibration of lecithin. -1 and 1153cm -1 The peaks at 1657-1429 cm are due to the antisymmetric stretching vibration of PO4 and the symmetric vibration of P=O. The appearance of these characteristic peaks indicates the successful loading of lysozyme. -1 and 1278-1000cm -1 The peaks at 1700–1550 cm-1 are related to C=C stretching and C=O stretching, respectively. The IR spectrum of Z / C-LE does not show any new peaks. This phenomenon may be due to the presence of the 1700–1550 cm-1 peak. -1 The broadband peak overlapped peaks appeared in the range of 1280 cm-1. This also indicates that there is an interaction between the hydroxyl molecules in EGCG and the amino groups in Z / C molecules. Z / C-LEP is at 1280 cm-1. -1 The absorption peak at 1663-1427 cm is related to the CO stretching vibration of phenolic aldehyde. -1The maximum absorption peaks of Z / C-EP, Z / C-LE and Z / C-LEP appear at 279nm, corresponding to C=O stretching vibration and CN stretching. Figure 1 (e) Interestingly, the absorbance intensity of Z / C-LEP increased with the addition of lysozyme.

[0054] 3. Polyphenol content and sustained release experiment (Appendix Figure 2 ):

[0055] Figure 2 (a) shows the total phenolic content of the edible emulsion after one month of aging. Compared to Z / C-LEP with lysozyme, the polyphenol content of the edible emulsion without lysozyme decreased significantly after one month of aging. This may be because the interaction of polyphenols with food components (such as proteins) may lead to significant aggregation and precipitation, resulting in functional or quantitative loss of polyphenols. We speculate that the addition of lysozyme has a significant impact on total phenolic stability, and the combined application of EGCG and perilla frutescens ethanol extract shows antioxidant synergy, which is influenced by lysozyme encapsulation. It has been suggested that the addition of lysozyme can prolong the maceration and micro-oxidation time to improve the color stability and polyphenol extraction of red wine. The combination of natural active ingredients with lysozyme affects the lysozyme activity and stability, as well as the biological activity of the active ingredients, such as antioxidant activity. Therefore, lysozyme can be used as an effective delivery vehicle for natural antioxidants.

[0056] Z / C-LE, Z / C-EP and Z / C-LEP edible emulsions were selected to test the release of polyphenols at room temperature. Within 12 h, the sustained release trends of Z / C-EP and Z / C-LEP were almost the same, reaching 23.84%. Figure 2 (b) Z / C-LE reached 15.23%. After 12 hours, the polyphenol release trends of Z / C-EP and Z / C-LEP gradually diverged. At 122 hours, the release of the three edible emulsions reached equilibrium, with Z / C-LEP releasing 84.72% of the polyphenols, Z / C-EP releasing 68.98%, and Z / C-LE releasing 55.07%. Clearly, at room temperature, the controlled release of polyphenols from Z / C-LEP can be sustained for a long time, demonstrating a highly effective and sustained antibacterial effect.

[0057] 4. Antibacterial test (attached Figure 2 ):

[0058] (1) Preparation of primary seed solution: 100 μL of Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) stored in the laboratory were placed in 100 mL of LB liquid culture medium (containing 5 g / L yeast powder, 5 g / L sodium chloride, and 10 g / L peptone) and cultured at a constant temperature with shaking for 14 h (37°C, 220 rpm) to obtain the primary seed solution.

[0059] (2) Preparation of secondary seed solution: 100 μL of each of the two primary seed solutions obtained in (1) was transferred to new 100 mL of LB liquid culture medium to obtain secondary seed solution.

[0060] (3) Determination of nucleic acid leakage: The loss of nucleic acid was tested at an absorbance of 260 nm using a microplate reader (51119500C, USA). The edible emulsion was added to a test tube containing Escherichia coli or Staphylococcus aureus and incubated in a phosphate buffer solution for 4 h (37 ° C). Centrifuged at 8000 rpm for 10 min and the precipitate was removed. The absorbance of the supernatant at 260 nm was measured and recorded. The sample without edible emulsion was used as a control. The change in optical density at 260 nm reveals the nucleic acid of the intracellular material. Figure 2 As shown in (c), after treatment with the edible emulsion, the values at 260 nm increased, with Z / C-LEP showing the largest increase. After sample treatment, the values at 260 nm increased by 12.68% for Staphylococcus aureus and by 7.77% for Escherichia coli. This suggests that after Z / C-LEP treatment, more DNA and RNA from Staphylococcus aureus leaked out of the cells, similar to Figure 2 The antibacterial activity trend in (d) indicates that Z / C-LEP has a good antibacterial effect against Staphylococcus aureus.

[0061] (4) Preparation of antibacterial stock solution and bacterial activity determination: 0.1 g each of Z / C, Z / CL, Z / C-LE, and Z / C-LEP was weighed and added to the secondary seed solution obtained in (2). The mixture was co-cultured with the bacteria and incubated with constant temperature shaking for 12 h (37°C, 220 rpm) to obtain the antibacterial stock solution. A blank control was also set up. The absorbance of the mixed solution was measured at 600 nm. All experiments were performed in triplicate. The bacterial activity was calculated according to Equation 1.

[0062] Bacterial activity = Abs / Absc×100% (1)

[0063] Where Abs is the absorbance value of the sample, and Absc is the absorbance of the control group containing bacterial suspension and LB medium without adding the sample.

[0064] like Figure 2 As shown in (d), Z / C exhibited the highest antibacterial activity (approximately 86%), while Z / C-LEP exhibited the lowest activity (approximately 40% and 28%). Z / CL and Z / C-LE exhibited activity between 50% and 80%, respectively. This indicates that the antibacterial activity of the perilla ethanol extract is relatively strong. Adding lysozyme significantly inhibited Staphylococcus aureus.

[0065] (5) Inhibition zone assay: The antibacterial activity of Z / C-LEP was further evaluated by the inhibition zone assay. Escherichia coli and Staphylococcus aureus were used as model bacteria for the assay. First, the bacterial suspension of Escherichia coli or Staphylococcus aureus obtained in (2) (200 μL, 10 5 -10 7 CFU / mL) were evenly spread on an agar plate, and then approximately 15 mg of Z / C, Z / CL, ZC-LE, and Z / C-LEP were added to the wells (d = 8 mm) of the agar plate. Finally, the agar plate was placed in a 37°C incubator. The growth of E. coli or S. aureus was recorded by photographing. Figure 2 (ef) There was a clear inhibition zone with a diameter of 15 mm and 18 mm around Z / CL. In addition, the inhibition zone diameters of the Z / C-LE sample were 19 mm and 23 mm, respectively. The inhibition diameters of Z / C-LEP were 25 mm and 29 mm, respectively. The inhibition zone of Z / C-LEP was irregular in the inhibition of E. coli, which may be due to the uneven diffusion of the antimicrobial active substances. The above results show that Z / C-LEP has a good inhibitory effect on both strains and has good antibacterial activity against Staphylococcus aureus. This result is consistent with the results of the bacterial activity test, proving that Z / C-LEP has good antibacterial properties.

[0066] 5. Antibacterial activity mechanism experiment (attached Figure 3 ):

[0067] From the histogram of LDH and ROS in Figure (3), it can be seen that Z / C, Z / CL, Z / C-LE and Z / C-LEP prepared in this example, Figure 3 As shown in (a), exposure to different materials increased the release of LDH in E. coli and S. aureus cells in the following order: Z / C-LEP>Z / C-LE>Z / C / L>Z / C. In addition, the order in which exposure to different materials induced ROS production in both bacteria was as follows: Figure 3 As shown in (b): Z / C-LEP > Z / C-LE > Z / C / L > Z / C. Furthermore, LDH and ROS release were greater in S. aureus than in E. coli. These results clearly indicate that Z / C-LEP is more toxic to bacterial cells, induces more robust ROS production, and reduces bacterial viability compared to edible emulsions containing other components, while edible emulsions containing other components are more effective against S. aureus. This is consistent with existing research showing that phenolic compounds interact with bacterial cell walls, leading to cell wall rupture and release of cellular contents, and can also induce endogenous oxidative stress in bacterial cells by inducing ROS formation.

[0068] 6. Antioxidant activity study (Appendix Figure 4 ):

[0069] like Figure 4 As shown, some antioxidant activity was observed even in edible emulsions without EGCG and zein; this may be due to the inherent antioxidant activity of chitosan and zein. Z / C-LE and Z / C-LEP exhibited high DPPH radical scavenging capacity. EGCG, the primary catechin in tea, possesses strong antioxidant activity. The addition of perilla enhanced this DPPH radical scavenging capacity. The antioxidant activity of perilla may be related to its phenolic and anthocyanin content. Perilla extract is considered an excellent free radical scavenger and a natural source of nutraceuticals and functional food ingredients, with several medical applications. These results suggest that EGCG and perilla alcohol extracts exhibit synergistic antioxidant activity. Furthermore, we observed that Z / C-LEP exhibited a higher antioxidant capacity than the other edible emulsions, reaching 70.41%. However, it did not exhibit a high antioxidant capacity. This is primarily due to the shielding of hydroxyl groups involved in the binding of polyphenols to lysozyme, which may account for its reduced antioxidant activity.

[0070] 7. Select the Z / C-LEP edible emulsion wrapped strawberry, place it for 21 days, the mass loss histogram (a) and the total acid titration histogram (b) (attached Figure 5 )

[0071] Based on the above experimental results, we evaluated the preservation effect of edible emulsions on strawberries. During storage, the changes in the appearance of the strawberries were carefully observed and monitored. After 20 days of storage, the appearance of the uncoated strawberries showed signs of rot and mold, while the appearance of the coated samples remained good as shown in Figure 2. Figure 5 (a). In addition, at 4°C, the weight of naked strawberries decreased by about 16%, while the weight loss of strawberries with different coatings was lower than that of the control at the end of the storage period, and Z / C-LEP maintained more than about 90% of its original weight. Figure 5 (b) To further understand the effects of different coatings on strawberry preservation, we further evaluated the preservation effect of edible emulsions using two chemical quality indicators, titratable acidity and Vc.

[0072] The decrease in titratable acidity during storage may be due to metabolic changes, such as the production of organic acids during the respiration of the fruit. Figure 5 (c) As shown in Figure 3, the titratable acidity of Z / C and Z / CL was not significantly different from that of the control. In contrast, the titratable acidity of Z / C-LE and Z / C-LEP was significantly different from that of the control, with Z / C-LEP having a higher titratable acidity than Z / C-LE.

[0073] The loss of vitamin C in fruits during storage is due to the spontaneous oxidation of ascorbic acid when it combines with oxygen in the air. Figure 5 As shown in (d), the Vc content of the control was less than 8 mg / 100 g, while the Vc concentrations of the coated strawberries were all higher than the control. The Vc contents of Z / C, Z / CL, ZC-LE, and Z / C-LEP were 27.3, 67.2, 78.8, and 95 mg / 100 g, respectively. The results indicate that the edible emulsion coating can act as a protective layer to control the permeability of O2 and CO2, thereby reducing the autoxidation of ascorbic acid. The Z / C-LEP-coated strawberries showed improved appearance and weight, as measured by coating freshness, weight loss, titratable acid content, and Vc content, with the highest titratable acid and Vc contents. We demonstrate that the Z / C-LEP edible emulsion is the most suitable for preserving strawberries.

[0074] 8. Z / C-LEP edible emulsion washability and freshness preservation of the wide application (attached Figure 6 )

[0075] Because consumers may prefer the taste of uncoated fruit. To prove the washability of the membrane, the sacred fruit with Z / C-LEP protective layer was immersed in deionized water. After 10 seconds, Z / C-LEP began to fall off from the sacred fruit into the deionized water, which shows that Z / C-LEP has good washability. Figure 6 (a). The results showed that as a fruit wrap, it could be easily removed from the fruit surface by rinsing with water. This further demonstrates that, in contrast to currently used non-washable wax coatings, the coating can be easily removed from fruit skin by rinsing with water and gently rubbing on the surface.

[0076] To explore the effect of Z / C-LEP on the freshness of other fruits and vegetables, we selected tomatoes and red peppers, mushrooms, broccoli and avocado as the objects of preservation. Figure 6 (b). After 14 days of shelf life, all uncoated vegetables were seen to be moldy and wrinkled. Vegetables coated with Z / C-LEP remained in good condition. Similarly, after 7 days of storage, uncoated avocados were found to be oxidized and blackened, and were found to have lost water and dried out after cutting. However, the coated avocados still maintained their shape well. Blackened parts were found after cutting, and despite having a protective film to block air, this fruit, which is not easy to preserve after cutting, still had quality problems after 7 days of storage. Overall, the shelf life of fruits and vegetables coated with Z / C-LEP emulsion was better than that of the control group, indicating that this edible emulsion has a better preservation effect on fruits and vegetables.

[0077] The present invention uses zein and chitosan as the delivery system, and lysozyme, EGCG and perilla frutescens ethanol extract are successfully loaded through hydrogen bonding and electrostatic bonding. A dual synergistic edible emulsion system with synergistic antibacterial and synergistic antioxidant properties was constructed. The results showed that Z / C-LEP has good sustained-release, antibacterial and antioxidant properties. Water washability can also reduce food safety and potential flavor issues associated with edible emulsions. A 20-day fruit freshness study on strawberries confirmed that the formula of the edible emulsion maintained the freshness and appearance of the strawberries. To further test the application of the edible emulsion, preservation experiments were conducted on different fruits and vegetables, and the results showed good preservation effects. Since the materials used to make the emulsion are edible and abundant, edible emulsions are expected to become an effective strategy for preserving fruits and vegetables.

[0078] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An edible emulsion, characterized in that Zein and chitosan were used as the base, and lysozyme, epigallocatechin gallate and perilla frutescens ethanol extract were added into the zein and chitosan as fillers. The preparation steps of the edible emulsion are as follows: (1) Zein was dispersed in 70% ethanol aqueous solution and magnetically stirred for 10 min to obtain a zein dispersion; (2) Disperse chitosan in 1% acetic acid aqueous solution and stir magnetically for 10 min to obtain chitosan dispersion; (3) The zein dispersion and chitosan dispersion obtained in step (1) and step (2) were mixed, ultrasonically treated at 450 W for 5 min, placed in a 75°C water bath for 30 min, and finally cooled at 4°C to terminate the reaction, thereby obtaining a Z / C mixed solution, i.e., a mixed solution of zein and chitosan; (4) adding lysozyme to the Z / C solution obtained in step (3) and magnetically stirring for 5 min to obtain a Z / CL dispersion, i.e., a dispersion of zein, chitosan, and lysozyme; (5) EGCG was added to the Z / CL dispersion obtained in step (4), and magnetic stirring was performed for 5 min to obtain a Z / C-LE dispersion, i.e., a dispersion of zein, chitosan, lysozyme, and EGCG; (6) The perilla frutescens alcohol extract was added to the Z / C-LE dispersion obtained in step (5), and magnetic stirring was performed for 5 min to obtain a Z / C-LEP dispersion, i.e., an edible emulsion of zein, chitosan, lysozyme, EGCG, and perilla frutescens alcohol extract.

2. An edible emulsion according to claim 1, characterized in that, In step (3), the mass ratio of zein to chitosan is 1-10:

1.

3. An edible emulsion according to claim 1, characterized in that, In step (4), the mass ratio of lysozyme to Z / C is 1-10:

800.

4. An edible emulsion according to claim 1, characterized in that In step (5), the mass ratio of EGCG to Z / CL is 1-5:

800.

5. An edible emulsion according to claim 1, characterized in that, In step (6), the mass ratio of the perilla frutescens ethanol extract to Z / C-LE is 1-10:

800.

6. Use of the edible emulsion according to any one of claims 1 to 5, wherein the solution finally prepared in step (6) is stirred at 60°C, the heated solution is poured into a Teflon box, and dried to finally obtain an edible emulsion antibacterial film material.

7. The use of the edible emulsion according to claim 6, characterized in that The edible emulsion antibacterial film material is used for antibacterial treatment of pathogenic bacteria including Escherichia coli and Staphylococcus aureus.

Images