Plant-derived natural preservative compound as well as preparation method and application thereof

Abstract

The invention provides a plant source anti-corrosion compound as well as a preparation method and application of the plant source anti-corrosion compound. The feed additive is prepared from the following components in parts by weight: 3 to 5 parts of clove extract, 3 to 5 parts of rosemary extract, 2 to 4 parts of star anise extract, 0.2 to 0.5 part of nisin, 0.1 to 0.3 part of natamycin, 0.1 to 0.5 part of epsilon-polylysine, 0.1 to 0.5 part of vitamin E, 0.1 to 0.5 part of sodium alginate, 1 to 2 parts of chitosan, 5 to 10 parts of maltodextrin and 2 to 4 parts of starch octenyl succinate. The double-wall material microencapsulated plant source preservative compound disclosed by the invention is used as a preservative, under the addition amount of 0.3 wt%, the normal-temperature shelf life of baked food can be prolonged from 3 days to 9-12 days, and the inhibition rate for aspergillus niger, aspergillus flavus, saccharomyces cerevisiae and bacillus subtilis is gt; the quality and the flavor are not influenced; the three major pain points of thermal stability, flavor compatibility and antibacterial broad spectrum are synchronously solved; the process is simple and wide in application prospect.

Description

Technical Field

[0001] This invention relates to the field of food preservation technology, specifically to a plant-derived natural preservative compound, its preparation method, and its application. Background Technology

[0002] In the field of food technology, preservatives hold a crucial position. With economic and technological development, people have gradually discovered the significant threat posed to human health by chemically synthesized food preservatives. The GB 2760-2024 standard officially banned sodium dehydroacetate. Consequently, countries worldwide have dedicated themselves to the research and development of broad-spectrum, safe, and highly effective food preservatives. The baking industry faces the dilemma of having no highly effective natural preservative alternatives. Existing plant extract preservatives have the following drawbacks: First, they have poor thermal stability; most plant active ingredients (such as phenolic acids and flavonoids) have a degradation rate >60% when baking at temperatures above 180℃. Second, they have a narrow antibacterial spectrum, with limited inhibitory effects on molds and yeasts, failing to cover the main spoilage bacteria in baked goods. Additionally, they cause flavor interference problems; for example, grape seed extract and tea polyphenols can impart a bitter taste, affecting the aroma of baked goods. Furthermore, some plant extract preservatives have poor process compatibility. Liquid extracts are difficult to mix evenly with flour, easily leading to localized over-mixing or ineffectiveness.

[0003] Therefore, developing a heat-resistant, broad-spectrum, flavor-synergistic, and process-friendly natural preservative system has become an urgent need for the industry. Summary of the Invention

[0004] To address the problems of existing plant-derived preservatives, this invention proposes a plant-derived preservative complex, its preparation method, and its application. Overcoming the shortcomings of existing technologies, such as the plant-derived preservative complex's inability to withstand high temperatures, flavor interference, and poor antibacterial properties, the application of this invention's plant-derived preservative complex in baked goods effectively improves the stability and safety of the food.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A plant-derived natural preservative compound, characterized in that it comprises the following components in parts by weight:

[0006] The main component of the ethanol extract of clove is eugenol, accounting for 70%-85% of the volatile oil. Other components include acetyleugenol, β-caryophyllene, quercetin, vanillin, and phenolic acids such as kaempferol, ferulic acid, caffeic acid, and ellagic acid. It has antifungal and antioxidant effects. The main antioxidant and anti-inflammatory components of rosemary ethanol extract are carrageenan, carrageenan, rosmarinic acid, chlorogenic acid, caffeic acid, ferulic acid, as well as flavonoids such as hesperidin and apigenin; it also contains a small amount of volatile oil components (α-pinene, eucalyptol, etc.); it has anti-lipid oxidation and antibacterial effects. Star anise extract is characterized by trans-anethole (over 70%) as its volatile oil component; it also contains chlorogenic acid, kaempferol, rutin and other phenolic acids and flavonoids, which are important contributors to its antioxidant and antibacterial activities. These natural spices work synergistically with food.

[0007] Nisin is a 34-amino acid peptide produced by *Lactococcus lactis*, belonging to the lantibiotic class. It possesses antimicrobial properties against Gram-positive bacteria and is heat-stable. Nisin first binds to lipid II (a precursor to peptidoglycan synthesis) on the bacterial cell membrane, forming a "pyrophosphate cage" that blocks cell wall synthesis. The mechanism of nisin's antibacterial action is as follows: it first forms a membrane pore; after binding to lipid II, nisin inserts into the cell membrane, forming a stable transmembrane channel, leading to leakage of cell contents and ultimately bacterial death.

[0008] Secondly, in addition to pore formation, Nisin can further inhibit cell wall synthesis by "removing" lipid II from the cell membrane.

[0009] Natamycin targets molds and yeasts, enhancing its antifungal effect and broadening its antibacterial spectrum. ε-Polylysine exhibits broad-spectrum antibacterial activity, synergistically with Nisin; Vitamin E (tocopherol), as an antioxidant, works with rosemary extract to prevent oil oxidation and enhance preservative effects.

[0010] Chitosan (degree of deacetylation ≥85%) has the functions of film formation, sustained release, and enhanced thermal stability; maltodextrin (DE 10–15) acts as a carrier, spray drying aid, and glass transition temperature regulator. Enhancing octenyl succinate starch ester (OSAS) improves emulsification stability, heat resistance, and reduces moisture sensitivity. Furthermore, the preparation method of the plant-derived natural preservative compound includes the following steps: (1) Extract cloves, rosemary and star anise with ethanol and concentrate under reduced pressure; (2) The concentrated solution obtained in step (1) and the lactic acid nisin, natamycin and ε-polylysine were dissolved in a citrate buffer solution at pH 4.0 to obtain the inner aqueous phase; (3) Dissolve vitamin E and octenyl succinate starch ester in 15-30g of medium-chain triglycerides, heat to 60℃ to dissolve and obtain the oil phase; slowly add the inner aqueous phase to the oil phase, and shear at high speed to form W / O colostrum; (4) Chitosan aqueous solution, maltodextrin aqueous solution and whey protein solution are mixed evenly to obtain an external aqueous phase. W / O promulgated emulsion is added dropwise to the external aqueous phase and sheared at high speed to form W / O / W double emulsion. High pressure micro-jet homogenization is performed to obtain nano-emulsion particles. Spray drying is performed to obtain microencapsulated plant-derived natural preservative complex with a moisture content of <4%.

[0011] Further, in step (1), the concentration of ethanol is 70% ethanol, the material-to-liquid ratio is 1:8-12, the ethanol extraction temperature is 45-55℃, and the extraction is performed 2-3 times, each time for 0.5-1.5h.

[0012] Furthermore, in step (1), ultrasonic extraction is used with an ultrasonic power of 200-300W; the solid content of the concentrated extract is 8-30wt%; preferably, the solid content is 8-20wt%, and more preferably, the solid content is 8-15wt%.

[0013] Further, in step (2), the concentration of nisin in the aqueous phase is 0.1-0.3 wt%; further, in step (3), the shear rate of high-speed shear emulsification is 8000-10000 rpm, the time is 8-15 min, and the temperature is 38-45℃.

[0014] Furthermore, in step (4), the concentration of chitosan in the external aqueous phase is 1.8-2.5% (w / v). Furthermore, in step (4), the shear rate of high-speed shear emulsification is 7000-9000 rpm, the time is 8-15 min, and the temperature is 38-45℃; the pressure of high-pressure micro-jet homogenization is 12000-16000 psi, and the cycle is 2-3 times.

[0015] Furthermore, in step (4), the inlet air temperature of the spray drying is 170-180℃, the outlet air temperature is 70-90℃, the feed rate is 12-15ml / min, and the atomization pressure is 0.2-0.3MPa.

[0016] Furthermore, the plant-derived natural preservative compound is used in baked goods, including toast, sweet bread, cakes, mooncakes, and egg yolk pastries.

[0017] Furthermore, the baking temperature of the baked food is below 200°C.

[0018] Furthermore, the amount of the plant-derived natural preservative complex added is 0.2-0.5 wt% of the flour mass; it is added at the end of the dough kneading process; and / or the plant-derived natural preservative complex is redispersed in water with a solid content of 5-10 wt%, and a film-forming agent pullulan is added, and then sprayed onto the surface of the bread after it has cooled.

[0019] The beneficial effects of this invention are: 1. This invention provides a microencapsulated plant-derived preservative complex, comprising double-walled microcapsules prepared from extracts of clove, rosemary, and star anise, along with nisin, natamycin, ε-polylysine, vitamin E, chitosan, sodium alginate, maltodextrin, octenyl succinate starch ester, and whey protein. At an addition of 0.3%, this microencapsulated plant-derived preservative complex can extend the shelf life of baked goods at room temperature from 3 days to 9 days, and exhibits inhibition rates >90% against Aspergillus niger, Aspergillus flavus, Saccharomyces cerevisiae, and Bacillus subtilis. 2. The microencapsulated plant-derived preservative complex provided by this invention has an ingenious structural design. The components of the microcapsule core material work synergistically to inhibit bacteria, broaden the antibacterial spectrum, and improve the inhibitory effect on molds and heat-resistant Bacillus. At the same time, it maintains compatibility with food flavor. The double-wall material significantly improves the thermal stability of the preservative complex and slow release during storage, thus extending the antibacterial period. The microencapsulated plant-derived preservative complex of this invention has three major advantages when used in baking food processing: thermal stability, flavor compatibility, and broad-spectrum antibacterial activity. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0021] This embodiment prepares a plant-derived natural preservative compound. The preparation steps are as follows: 1. Preparation of plant extracts Four parts cloves, four parts rosemary and three parts star anise were pulverized to 40 mesh and 70 ethanol was added at a ratio of 1:10 (w / v). The mixture was ultrasonically extracted twice at 50°C for 1 hour each time at a power of 250W. The filtrates were combined and concentrated under reduced pressure (vacuum degree -0.08 MPa, 50℃) to a solid content of 15wt%; the plant concentrate was obtained; it was stored at 4℃ away from light and used within 48 hours. 2. Preparation of bilayer emulsions According to the formula, 11 g of plant extract concentrate (15% solids content), 0.3 g Nisin, 0.2 g natamycin, and 0.3 g ε-polylysine were dissolved in citrate buffer at pH 4.0 to obtain the inner aqueous phase; the concentration of nisin in the inner aqueous phase was 0.2 wt%. Dissolve 0.7g vitamin E and 3g OSAS in 15g medium chain triglycerides (MCT), heat to 60℃ to dissolve, slowly add the inner aqueous phase to the oil phase, and shear at high speed (10000rpm, 5min) to form W / O colostrum.

[0022] 1.5g of chitosan was prepared into an aqueous solution (dissolved in a 1wt% lactic acid solution), 1g of sodium alginate, 8g of maltodextrin, and 2g of whey protein were mixed evenly to obtain an external aqueous phase, wherein the concentration of chitosan in the external aqueous phase was 2% (w / v). W / O primary emulsion was dropwise added to the external aqueous phase and subjected to high-speed shearing (8000 rpm for 10 min, water bath temperature 40℃) to form a W / O / W dual emulsion; homogenized in a high-pressure microfluidic homogenizer (pressure 15000 psi, 2 cycles) to obtain nanoemulsion particles with D50≤200nm. 3. Spray drying and post-treatment The obtained emulsion was spray-dried and microencapsulated with parameters of inlet air temperature 180℃, outlet air temperature 80℃, atomization pressure 0.2 MPa, and feed rate 10 ml / min. The microencapsulated plant preservative powder was obtained by cyclone separator and electrostatic collector. The obtained microcapsules were light yellow powder with a moisture content of <4%. They were vacuum-packed in aluminum foil bags, nitrogen-filled for protection, and stored away from light. Example 2

[0023] This embodiment prepares a plant-derived natural preservative compound. The preparation steps are as follows: 1. Preparation of plant extracts Three parts cloves, five parts rosemary, and four parts star anise were pulverized to 40 mesh and then added to 75% ethanol at a ratio of 1:8 (w / v). The mixture was ultrasonically extracted three times at 45°C for 0.5 hours each time, with a power of 200W. Combine the filtrates and concentrate under reduced pressure (vacuum degree -0.08 MPa, 50℃) to a solid content of 15wt%; obtain plant concentrate; store at 4℃ protected from light and use within 48 hours; 2. Preparation of bilayer emulsions According to the formula, 12 g of plant extract concentrate (converted to dry matter), 0.2 g of Nisin, 0.3 g of natamycin, and 0.5 g of ε-polylysine were dissolved in citrate buffer at pH 4.0 to obtain the inner aqueous phase; the concentration of nisin in the inner aqueous phase was 0.3 wt%. 1g of vitamin E and 4g of OSAS were dissolved in 30g of medium-chain triglycerides (MCT), and the mixture was heated to 60°C to obtain the oil phase. The inner aqueous phase was slowly added to the oil phase, and the mixture was sheared at high speed (11000 rpm, 5 min) to form a W / O colostrum.

[0024] 2g of chitosan was prepared into an aqueous solution (dissolved in a 1wt% lactic acid solution), 1.5g of sodium alginate, 10g of maltodextrin, and 1-3g of whey protein were mixed evenly to obtain an external aqueous phase with a chitosan concentration of 2.5% (w / v). W / O primary emulsion was dropped into the external aqueous phase and subjected to high-speed shearing (9000 rpm for 10 min, water bath temperature 40℃) to form a W / O / W dual emulsion; homogenized in a high-pressure microfluidic homogenizer (pressure 16000 psi, 2 cycles) to obtain nanoemulsion particles with D50≤200nm. 3. Spray drying and post-treatment The obtained emulsion was spray-dried and microencapsulated with parameters of inlet air temperature 170℃, outlet air temperature 90℃, atomization pressure 0.2 MPa, and feed rate 10 ml / min. The microencapsulated plant preservative powder was obtained by cyclone separator and electrostatic collector. The obtained microcapsules were light yellow powder with a moisture content of <4%. They were vacuum-packed in aluminum foil bags, nitrogen-filled for protection, and stored away from light. Example 3

[0025] This embodiment prepares a plant-derived natural preservative compound. The preparation steps are as follows: 1. Preparation of plant extracts Five parts cloves, three parts rosemary, and two parts star anise were pulverized to 40 mesh and then added to 65% ethanol at a ratio of 1:12 (w / v). The mixture was ultrasonically extracted twice at 55°C for 1.5 hours each time, with a power of 200W. Combine the filtrates and concentrate under reduced pressure (vacuum degree -0.08 MPa, 50℃) to a solid content of 8wt%; obtain plant concentrate; store at 4℃ protected from light and use within 48 hours; 2. Preparation of bilayer emulsions According to the formula, 12 g of plant extract concentrate (converted to dry matter), 0.5 g of Nisin, 0.1 g of natamycin, and 0.1 g of ε-polylysine were dissolved in citrate buffer at pH 4.0 to obtain the inner aqueous phase; the concentration of Nisin in the inner aqueous phase was 0.1 wt%. Dissolve 0.5g vitamin E and 2g OSAS in 15g medium chain triglycerides (MCT), heat to 60℃ to dissolve and obtain the oil phase. Slowly add the inner aqueous phase to the oil phase and shear at high speed (9000rpm, 5min) to form W / O colostrum.

[0026] 1g of chitosan was prepared into an aqueous solution (dissolved in a 1wt% lactic acid solution), 0.5g of sodium alginate, 5g of maltodextrin, and 1-3g of whey protein were mixed evenly to obtain an external aqueous phase with a chitosan concentration of 1.8% (w / v). W / O primary emulsion was dropwise added to the external aqueous phase and subjected to high-speed shearing (7000 rpm for 10 min, water bath temperature 40℃) to form a W / O / W dual emulsion; homogenized in a high-pressure microfluidic homogenizer (pressure 12000 psi, 3 cycles) to obtain nanoemulsion particles with D50≤200nm. 3. Spray drying and post-treatment The obtained emulsion was spray-dried and microencapsulated with parameters of inlet air temperature 180℃, outlet air temperature 70℃, atomization pressure 0.2 MPa, and feed rate 10 ml / min. The microencapsulated plant preservative powder was obtained by cyclone separator and electrostatic collector. The obtained microcapsules were light yellow powder with a moisture content of <4%. They were vacuum-packed in aluminum foil bags, nitrogen-filled for protection, and stored away from light. Comparative Example 1

[0027] This comparative example prepares a plant-derived natural preservative complex. The difference between this comparative example and Example 1 is that chitosan and maltodextrin are not added; the microencapsulation step is not performed; and the plant-derived natural preservative complex is prepared by drying an equal amount of a mixture of clove extract, rosemary extract, star anise extract, nisin natamycin, and vitamin E. Comparative Example 2

[0028] This comparative example prepares a plant-derived natural preservative complex. The difference from Example 1 is that this comparative example uses single-wall microcapsules; chitosan and maltodextrin are used as wall materials. The preparation steps are as follows: 1. Preparation of plant extracts Four parts cloves, four parts rosemary and three parts star anise were pulverized to 40 mesh and 70 ethanol was added at a ratio of 1:10 (w / v). The mixture was ultrasonically extracted twice at 50°C for 1 hour each time at a power of 250W. The filtrates were combined and concentrated under reduced pressure (vacuum degree -0.08 MPa, 50℃) to a solid content of 15wt%; the plant concentrate was obtained; it was stored at 4℃ away from light and used within 48 hours. 2. Single-wall material cladding 1.5g of chitosan was prepared into an aqueous solution (dissolved in a 1wt% lactic acid solution), 1g of sodium alginate, 8g of maltodextrin, and 2g of whey protein were mixed evenly to obtain the aqueous phase of the wall material, wherein the concentration of chitosan in the outer aqueous phase was 2% (w / v). 11 g of plant concentrate (dry matter equivalent), 0.3 g of Nisin, 0.2 g of natamycin, 0.3 g of ε-polylysine, and 0.7 g of vitamin E were added to the aqueous phase of the wall material and mixed thoroughly. The mixture was then treated using a high-speed shear emulsifier at 8000 rpm for 10 min at 40°C (water bath temperature control). A homogeneous emulsion with a particle size <500 nm (D50) was finally formed. The drying and storage methods are the same as in Example 1. Comparative Example 3

[0029] This comparative example prepares a plant-derived natural preservative compound. The difference from Example 1 is that Nisin and ε-polylysine are not added, and the amount of natamycin is 0.8g. The remaining steps are the same as in Example 1. Application Example 1

[0030] The amount of the plant-derived natural preservative compound from Example 1 added was 0.3 wt% based on the weight of flour; when preparing the toast product, it was added at the end of the dough kneading process to avoid inhibiting fermentation; Texture effect: TPA test showed that the changes in hardness, elasticity and chewiness were <5%, with no significant difference (p>0.05).

[0031] Antibacterial rate: Aspergillus niger 92%, Saccharomyces cerevisiae 88%, Bacillus subtilis 95%. Application Example 2

[0032] The plant-derived natural preservative complex from Example 2 was added at the end of the dough kneading process; the amount added was 0.2 wt% based on the flour mass; and the crust of Cantonese-style mooncakes was prepared. Flavor assessment: It complements the aromas of cinnamon and dried tangerine peel, with no off-flavors; Comparative Application Example 1

[0033] The difference between this comparative application example and application example 1 is that the preservative added during the preparation of toast in this comparative example is the unencapsulated plant extract prepared in comparative example 1. Comparative Application Example 2

[0034] This comparative application example uses the plant-derived natural preservative compound prepared in Comparative Example 2, with an addition amount of 0.3 wt% based on the flour mass; it is used to prepare toast; the compound is added at the end of the dough kneading process to avoid inhibiting fermentation; Comparative Application Example 3

[0035] The difference between this comparative application example and application example 1 is that the toast was prepared using the natural preservative compound of comparative example 3. Comparative Application Example 4

[0036] The difference between this comparative application example and application example 1 is that no preservatives were added during the preparation of toast in this comparative example. Comparative Application Example 5

[0037] Unlike Comparative Application Example 1, this comparative example adds 0.3 wt% sodium dehydroacetate by weight of flour during the preparation of toast. Antibacterial test

[0038] Sample preparation: Take 10g of the center portion of each loaf of bread, chop it, and dry it in a 50℃ oven until constant weight.

[0039] Grind the flour through a 60-mesh sieve to obtain bread flour.

[0040] Extraction method (simulating migratory antimicrobial components in food): Weigh 2.0g of bread flour and add 20mL of pH 5.5 phosphate buffer (to simulate the internal environment of bread).

[0041] Extract by shaking at 40℃ for 2 hours, centrifuge (8000 rpm, 10 min), and filter the supernatant through a 0.22 μm filter membrane for sterilization.

[0042] Store the extract at 4°C and use within 24 hours.

[0043] Agar diffusion method operation steps 1. Test strains and culture media Aspergillus niger ATCC 16404 → PDA medium Aspergillus flavus ATCC 22546 → PDA medium Saccharomyces cerevisiae ATCC 9763 → YPD medium Bacillus subtilis ATCC 6633 → NA medium 2. Preparation of bacterial suspension Mold: spore suspension 1×10 6 spores / mL (containing 0.05% Tween-80) Yeast: 1×10⁻⁶ cells / day suspension 7 CFU / mL Bacteria: Spore suspension 1×10 6 CFU / mL (treated in a boiling water bath for 10 min) 3. Preparation of antibacterial plates Melt the culture medium and cool it to 45°C. Add the bacterial suspension at a 1% inoculation rate, mix well, pour into a plate (20 mL / plate), and after solidification, punch holes (6 mm in diameter, 25 mm spacing). 4. Sample addition and incubation Sample test: Add 80 μL of bread extract from Application Example 1 and Comparative Examples 1-4 to each well. Negative control: Used extract from Example 4 (without preservatives).

[0044] Positive controls: 0.1% potassium sorbate solution (mold / yeast), 0.1% ethylparaben solution (bacteria) Pre-diffusion at 4℃ for 3 hours, followed by incubation at suitable temperatures (28℃ / 72 hours for molds, 28℃ / 48 hours for yeasts, and 37℃ / 24 hours for bacteria).

[0045] Inhibition zone measurement: Measure the outer diameter of the inhibition zone (including the hole) with vernier calipers, in mm; 3 parallel measurements per group, take the mean ± standard deviation.

[0046] 2. Calculation of antibacterial activity Inhibition rate (%) = (Diameter of inhibition zone of sample - Diameter of negative control) / (Diameter of positive control - Diameter of negative control) × 100% Relative antibacterial efficacy index: The relative value of other application examples is calculated based on application example 1 (100%). Implementation effect

[0047] Antibacterial experiments were conducted using the agar diffusion method. The inhibition zone effects of *Aspergillus niger*, *Aspergillus flavus*, *Saccharomyces cerevisiae*, and *Bacillus subtilis* in the application examples and control examples are shown in Table 1.

[0048] The antibacterial rate (%) is shown in Table 2:

[0049] Application Example 1 uses the bilayer microcapsules prepared in Example 1 of this invention. The MCT oil phase buffers thermal shock, and the activity retention rate is >90%. The wall material controls the release, and the antibacterial effect is long-lasting. Nisin, plant extracts and natamycin work synergistically to inhibit bacteria in a broad spectrum.

[0050] Compared to the application example 1, which uses a non-microencapsulated preservative combination, the antibacterial effect was significantly reduced to 30-40%. This is because the active ingredients degrade and volatilize during baking, with rapid initial release and weak antibacterial effect in the later stages; high temperature leads to a decrease in flavor; and excessively high local concentrations affect fermentation.

[0051] Compared with application example 2, which uses single-walled microcapsules, the antibacterial rate decreased to about 50-60% because it lacks an oil phase layer and has poor thermal stability; the sustained-release effect is weaker than that of the double-layer structure.

[0052] Compared to Example 3, which did not include Nisin and ε-polylysine, increasing the dosage of natamycin to 0.8g reduced the antibacterial rate to 50-90%, with significant fluctuations and a narrower antibacterial spectrum. While the effect against molds and yeasts was acceptable, the antibacterial rate against Bacillus subtilis decreased significantly from 89.33% to 55%. This indicates that Nisin and ε-polylysine have a synergistic antibacterial effect with plant extracts and natamycin.

[0053] In contrast, application example 5 has been banned, indicating low acceptance of chemical preservatives.

[0054] Food texture includes changes in hardness, elasticity, and chewiness. The results of flavor sensory tests are shown in Table 3. Table 3:

[0055] Note: The shelf life is the date when the mold has completely covered the surface.

[0056] As shown in Table 3, Examples 1 and 2 are plant-derived natural preservative complexes prepared according to the present invention. They have very good preservative effects in Application Examples 1 and 2, and the shelf life is longer than that of the comparative example. After adding 0.3% of the plant-derived natural preservative complex of the present invention to toast bread, the shelf life was extended from 3 days to 12 days compared with the comparative example 3 without preservatives. Moreover, the addition of the plant-derived natural preservative complex of the present invention synergistically promotes the aroma of ingredients such as tangerine peel in mooncake food, and the flavor complements each other without affecting the taste.

[0057] Compared with Comparative Application Example 1, the microencapsulated plant-derived natural preservative complex of the present invention has a better preservative effect. The microencapsulated double-wall material in the present invention can increase the Tg of the plant-derived natural preservative complex, so that the retention rate of active ingredients is >95% after baking at 200°C for 10 min, avoiding the volatilization of cloves in the early stage of baking. In addition, the microencapsulated wall material isolates O2, preventing rosmarinic acid and flavonoids from oxidizing and turning brown and deteriorating in flavor at high temperature. At the same time, it provides a slow-release effect, stably and continuously releasing antibacterial agents and extending shelf life.

[0058] The results of the comparative application example 2 show that the antibacterial rate decreased to 50-60% when using single-wall material; single-wall material reduces stability and heat resistance, and the fragrance components in the plant extracts are severely lost due to volatilization after heating, resulting in poor antibacterial effect and shorter shelf life.

[0059] Comparative Example 3 shows that the lack of Nisin and ε-polylysine narrows the antibacterial spectrum, thus reducing the shelf life to 9 days. This indicates that Nisin and ε-polylysine work synergistically with the plant extracts and natamycin of this invention to have a more broad-spectrum antibacterial effect.

[0060] The results of Comparative Example 4 show that although sodium dehydroacetate has a good antibacterial effect and can preserve food for a longer period of time, its use has been explicitly prohibited. In summary, the plant-derived natural preservative complex of this invention has comparable preservative effects to this chemical substance, better taste, and is more human-friendly, possessing broad prospects for industrialization.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A plant-derived natural preservative compound, characterized in that, Includes the following components by weight:

2. The method for preparing the plant-derived natural preservative compound according to claim 1, characterized in that: Includes the following steps: (1) Extract cloves, rosemary and star anise with ethanol and concentrate under reduced pressure; (2) The concentrated solution obtained in step (1) and converted to dry matter weight is dissolved in pH 1 with the lactic acid nisin, natamycin and ε-polylysine. The inner aqueous phase was obtained in a 4.0 citrate buffer solution; (3) Dissolve vitamin E and octenyl succinate starch ester in 15-30g of medium-chain triglycerides, heat to 60℃ to dissolve and obtain the oil phase; slowly add the inner aqueous phase to the oil phase, and shear at high speed to form W / O colostrum; (4) Chitosan aqueous solution, sodium alginate aqueous solution, maltodextrin aqueous solution and whey protein solution are mixed evenly to obtain an external aqueous phase. W / O promulgated emulsion is added dropwise to the external aqueous phase and sheared at high speed to form W / O / W double emulsion. The emulsion is homogenized by a high-pressure micro-jet homogenizer to obtain nano-emulsion particles. Spray drying is performed to obtain microencapsulated plant-derived natural preservative complex with a moisture content of <4%.

3. The method for preparing the plant-derived natural preservative compound according to claim 2, characterized in that: The concentration of ethanol used in step (1) is 65-75% ethanol, and the material-to-liquid ratio for extraction is 1:8-12; the ethanol extraction temperature is 45-55℃, and the extraction is performed 2-3 times, each time for 0.5-1.5 hours.

4. The method for preparing the plant-derived natural preservative compound according to claim 3, characterized in that: In step (1), ultrasonic-assisted extraction is used with an ultrasonic power of 200-300W; the solid content of the concentrated extract is 8-30wt%.

5. The method for preparing the plant-derived natural preservative compound according to claim 3, characterized in that: In step (2), the concentration of nisin in the aqueous phase is 0.1-0.3 wt%.

6. The method for preparing the plant-derived natural preservative compound according to claim 2, characterized in that: In step (4), the concentration of chitosan in the external aqueous phase is 1.8-2.5% (w / v).

7. The method for preparing the plant-derived natural preservative compound according to claim 2 or 3, characterized in that: In step (3), the shear rate of high-speed shear emulsification is 8000-11000 rpm and the time is 8-15 min; in step (4), the shear rate of high-speed shearing is 7000-9000 rpm and the time is 8-15 min; the pressure of high-pressure micro-jet homogenization is 12000-16000 psi and the cycle is 2-3 times.

8. The method for preparing the plant-derived natural preservative compound according to claim 7, characterized in that: In step (4), the inlet air temperature of the spray dryer is 170-180℃, the outlet air temperature is 70-90℃, the feed rate is 12-15ml / min, and the atomization pressure is 0.2-0.3MPa.

9. The application of the plant-derived natural preservative compound of claim 1 in baked goods, characterized in that: The baked goods include toast, sweet bread, cakes, mooncakes, and egg yolk pastries; the baking temperature of the baked goods is 180-200℃.

10. The application of the plant-derived natural preservative compound according to claim 9 in baked goods, characterized in that: The amount of the plant-derived natural preservative compound added is 0.2-0.5 wt% of the flour mass; it is added at the end of the dough kneading process; and / or the plant-derived natural preservative compound is redispersed in water with a solid content of 5-10 wt%, and a film-forming agent pullulan is added, and then sprayed onto the surface of the bread after it has cooled.

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