Water-activated plant source food preservative and preparation method thereof

Abstract

This invention discloses a water-activated plant-derived food preservative and its preparation method. The preservative, by weight, comprises: 8-30 parts of a cruciferous plant glucosinolate concentrate, 1-8 parts of a plant-derived black mustard enzyme preparation, 3-15 parts of citrus peel essential oil, 5-20 parts of pomegranate peel polyphenol extract, 10-35 parts of low-methoxyl pectin, 15-45 parts of a cyclodextrin derivative, and 3-18 parts of a water activity regulator. The preparation method includes: separately preparing the glucosinolate concentrate and the plant-derived black mustard enzyme preparation with low black mustard enzyme activity; shearing and compounding the citrus peel essential oil, cyclodextrin derivative, and pomegranate peel polyphenol extract; and then mixing them with low-methoxyl pectin and the water activity regulator with low moisture content. This invention can inhibit premature reactions during storage and, upon contact with water, generates isothiocyanate-based antibacterial substances in situ, exhibiting advantages such as good stability, broad antibacterial spectrum, and excellent preservative effect.

Description

Technical Field

[0001] This invention relates to the field of preservative production technology, and in particular to a water-activated plant-derived food preservative and its preparation method. Background Technology

[0002] With increasing consumer demand for food safety, clean labeling, and natural preservation technologies, plant-based food preservatives have gradually become a research hotspot in the field of food preservation. Existing natural preservative systems mainly include plant essential oils, plant polyphenols, organic acids and their salts, plant polysaccharide coating materials, and plant fermentation products. Among these, citrus, oregano, cinnamon, and clove essential oils contain volatile active ingredients such as terpenes and phenols, exhibiting certain antibacterial and antifungal effects; pomegranate peel polyphenols, tea polyphenols, and grape seed polyphenols possess antioxidant, antibacterial, and food quality-deteriorating effects. Furthermore, glucosinolates from cruciferous plants can be hydrolyzed by myrosinase to generate isothiocyanates, which possess both volatile and contact phase antibacterial activity, showing potential application as a plant-based food preservative system.

[0003] However, existing natural plant preservatives still face the challenge of balancing stability and efficacy. Plant essential oils are highly volatile and poorly dispersible in water, easily producing irritating odors and affecting the original flavor of food when added directly. Plant polyphenols, when used alone, have limited antibacterial strength and are easily affected by proteins, metal ions, oxygen, and processing conditions in the food system, leading to a decrease in activity. For the glucosinolate-myrosinase system, if cruciferous plant powders or ordinary extracts are used directly, glucosinolates and endogenous myrosinase are prone to premature reaction during processing, mixing, or storage, resulting in the premature formation and volatilization of isothiocyanate active substances, making it difficult to achieve a stable and controllable antibacterial effect during food use. Therefore, there is an urgent need to develop a plant-derived food preservative that can inhibit the premature reaction of active ingredients during storage, generate antibacterial substances in situ upon contact with food moisture, and possess the synergistic effects of essential oils, polyphenols, and the glucosinolate-myrosinase system. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a water-activated plant-derived food preservative and its preparation method. This preservative comprises a cruciferous plant glucosinolate concentrate, a plant-derived black mustard enzyme preparation, citrus peel essential oil, pomegranate peel polyphenol extract, low-methoxyl pectin, cyclodextrin derivatives, and a water activity regulator. By using a low-moisture complex to inhibit premature reactions during storage, and upon contact with water, it generates isothiocyanate-based antibacterial substances in situ, achieving stable and synergistic preservation.

[0005] This invention can be achieved through the following technical solutions: A water-activated plant-derived food preservative, comprising, by weight, the following components: 8-30 parts of a cruciferous plant glucosinolate concentrate, 1-8 parts of a plant-derived black mustard enzyme preparation, 3-15 parts of citrus peel essential oil, 5-20 parts of pomegranate peel polyphenol extract, 10-35 parts of low-methoxyl pectin, 15-45 parts of a cyclodextrin derivative, and 3-18 parts of a water activity regulator; wherein the cruciferous plant glucosinolate concentrate and the plant-derived black mustard enzyme preparation undergo an enzymatic reaction in the presence of water to generate isothiocyanate antibacterial substances.

[0006] Preferably, the cruciferous plant glucosinolate concentrate is derived from one or more of mustard seeds, radish seeds, broccoli seeds, cabbage seeds, and rapeseed; and the glucosinolate content in the cruciferous plant glucosinolate concentrate is not less than 5%.

[0007] Preferably, the cruciferous plant glucosinolate enrichment is a plant extract with low myrosinase activity, and its endogenous myrosinase activity is less than 10 U / g.

[0008] Preferably, the plant-derived black mustard enzyme preparation is derived from one or more of mustard seeds, radish seeds, broccoli seeds, cabbage seeds, and rapeseed; the enzyme activity of the plant-derived black mustard enzyme preparation is 10-500 U / g.

[0009] Preferably, the citrus peel essential oil is one or more of sweet orange peel essential oil, lemon peel essential oil, grapefruit peel essential oil, and bergamot essential oil; the total polyphenol content of the pomegranate peel polyphenol extract is not less than 30%.

[0010] Preferably, the cyclodextrin derivative is one or more of hydroxypropyl-β-cyclodextrin, methyl-β-cyclodextrin, and sulfobutyl-β-cyclodextrin; and the water activity regulator is one or more of trehalose, erythritol, sorbitol, glycerol, and maltodextrin.

[0011] A method for preparing a water-activated plant-based food preservative includes the following steps: S1. The cruciferous plant raw material is subjected to enzyme inactivation treatment at 80-120℃ for 2-15 min, followed by low-temperature defatting and water-alcohol extraction to obtain a cruciferous plant glucosinolate enrichment; the cruciferous plant raw material is further crushed, extracted and concentrated under low-temperature conditions to obtain a plant-derived black mustard enzyme preparation. S2. Mix citrus peel essential oil with cyclodextrin derivatives and add pomegranate peel polyphenol extract. Shear the mixture at 6000-15000 r / min for 3-15 min to obtain essential oil-polyphenol-cyclodextrin complex. S3. The cruciferous plant glucosinolate enrichment obtained in step S1, the plant-derived black mustard enzyme preparation, the essential oil-polyphenol-cyclodextrin complex obtained in step S2, the low-methoxyl pectin and the water activity regulator are mixed at 15-40℃ to obtain a water-activated plant-derived food preservative.

[0012] Preferably, in step S1, when preparing the cruciferous plant glucosinolate enrichment, the low-temperature defatting temperature is 20-45°C; the volume fraction of ethanol in the water-alcohol extraction is 30%-80%, and the extraction temperature is not higher than 50°C.

[0013] Preferably, in step S1, when preparing the plant-derived black mustard enzyme preparation, the pulverization temperature is not higher than 35°C and the extraction temperature is not higher than 40°C; in step S3, the moisture content of the mixed system is controlled at 3-20% to inhibit the premature reaction between the cruciferous plant glucosinolate enrichment and the plant-derived black mustard enzyme preparation during the preparation process.

[0014] Preferably, the cruciferous plant raw material undergoes fermentation pretreatment before enzyme inactivation treatment: the cruciferous plant raw material is mixed with water, inoculated with lactic acid bacteria at an inoculation amount of 10⁵–10⁸ CFU / g, fermented at 25–37°C for 4–24 h, and after fermentation, enzyme inactivation treatment is performed to obtain fermentation pretreatment raw material for preparing cruciferous plant glucosinolate enrichment; the lactic acid bacteria are one or more of Lactobacillus plantarum, Lactobacillus rhamnosus, and Lactobacillus casei.

[0015] The beneficial effects of this invention are: This invention involves preparing a plant-derived food preservative system by separately preparing a cruciferous plant glucosinolate concentrate with low myrosinase activity and a plant-derived myrosinase preparation, and then combining them with citrus peel essential oil, pomegranate peel polyphenol extract, low-methoxyl pectin, cyclodextrin derivatives, and a water activity regulator under low moisture conditions. This system is stable during storage and activated upon contact with water during use. Compared with preservatives that are simply composed of plant extracts, essential oils, or polyphenols, this invention effectively inhibits the premature reaction between glucosinolates and myrosinase during preparation and storage, reducing the premature formation and volatilization loss of isothiocyanate active substances. Upon contact with moisture on the food surface, it can generate isothiocyanate antibacterial substances in situ, which synergize with the volatile antibacterial effect of citrus peel essential oil and the antioxidant and antibacterial effects of pomegranate peel polyphenols, thereby improving the inhibitory effect on bacteria, yeast, and mold. Meanwhile, cyclodextrin derivatives help reduce essential oil volatilization loss and improve dispersibility, water activity regulators help maintain a low moisture environment in the system, and low methoxyl pectin helps improve system stability, so that the resulting preservative has the advantages of natural source, good stability, water response, broad antibacterial spectrum and strong adaptability. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This refers to the antibacterial properties of the preservative samples. Detailed Implementation

[0017] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0018] Example 1: The water-activated plant-derived food preservative of this example comprises the following components by weight: 8 parts of cruciferous plant glucosinolate concentrate, 1 part of plant-derived black mustard enzyme preparation, 3 parts of citrus peel essential oil, 5 parts of pomegranate peel polyphenol extract, 10 parts of low-methoxyl pectin, 15 parts of cyclodextrin derivative, and 18 parts of water activity regulator; wherein, the cruciferous plant glucosinolate concentrate is derived from mustard seeds, and its glucosinolate content is 5%; the plant-derived black mustard enzyme preparation is derived from mustard seeds, and its enzyme activity is 10 U / g; the citrus peel essential oil is sweet orange peel essential oil; the total polyphenol content in the pomegranate peel polyphenol extract is 30%; the cyclodextrin derivative is hydroxypropyl-β-cyclodextrin; and the water activity regulator is trehalose.

[0019] The food preservative in this embodiment is prepared using the following steps: S1. Mustard seed raw material was mixed with water and inoculated with Lactobacillus plantarum at an inoculation amount of 105 CFU / g. Fermentation was carried out at 25℃ for 24 h. After fermentation, enzyme inactivation treatment was carried out at 80℃ for 15 min, followed by defatting and water-alcohol extraction at 20℃ to obtain a cruciferous plant glucosinolate enrichment. The volume fraction of ethanol in the water-alcohol extraction was 30%, and the extraction temperature was 50℃. Separately, mustard seed raw material was crushed at a temperature not exceeding 35℃, and extracted and concentrated at a temperature not exceeding 40℃ to obtain a plant-derived black mustard enzyme preparation. S2. Sweet orange peel essential oil is mixed with hydroxypropyl-β-cyclodextrin and pomegranate peel polyphenol extract is added. The mixture is sheared at 6000 r / min for 15 min to combine the citrus peel essential oil with the cyclodextrin derivative and to disperse the pomegranate peel polyphenol extract in the composite system, thus obtaining an essential oil-polyphenol-cyclodextrin complex. S3. The cruciferous plant glucosinolate enrichment obtained in step S1, the plant-derived black mustard enzyme preparation, the essential oil-polyphenol-cyclodextrin complex obtained in step S2, low-methoxyl pectin and trehalose are mixed at 15°C, and the moisture content of the mixture is controlled at 3% to inhibit the premature reaction between the glucosinolate enrichment and the plant-derived black mustard enzyme preparation during the preparation process, so as to obtain a water-activated plant-derived food preservative.

[0020] Example 2: The water-activated plant-derived food preservative of this example comprises the following components by weight: 19 parts of cruciferous plant glucosinolate concentrate, 4.5 parts of plant-derived black mustard enzyme preparation, 9 parts of citrus peel essential oil, 12.5 parts of pomegranate peel polyphenol extract, 22.5 parts of low-methoxyl pectin, 30 parts of cyclodextrin derivative, and 3 parts of water activity regulator; wherein, the cruciferous plant glucosinolate concentrate is derived from radish seeds, and its glucosinolate content is 5%; the plant-derived black mustard enzyme preparation is derived from radish seeds, and its enzyme activity is 255 U / g; the citrus peel essential oil is lemon peel essential oil; the total polyphenol content in the pomegranate peel polyphenol extract is 30%; the cyclodextrin derivative is methyl-β-cyclodextrin; and the water activity regulator is erythritol.

[0021] The food preservative in this embodiment is prepared using the following steps: S1. Radish seed raw material was mixed with water and inoculated with Lactobacillus rhamnosus at an inoculation amount of 106 CFU / g. Fermentation was carried out at 30℃ for 14 h. After fermentation, enzyme inactivation was performed at 100℃ for 8 min, followed by defatting and water-alcohol extraction at 35℃ to obtain a cruciferous plant glucosinolate enrichment. The volume fraction of ethanol in the water-alcohol extraction was 55%, and the extraction temperature was 50℃. Radish seed raw material was pulverized at a temperature not exceeding 35℃, and extracted and concentrated at a temperature not exceeding 40℃ to obtain a plant-derived black mustard enzyme preparation. S2. Lemon peel essential oil was mixed with methyl-β-cyclodextrin and pomegranate peel polyphenol extract was added. The mixture was sheared at 11000 r / min for 9 min to combine the citrus peel essential oil with the cyclodextrin derivative and to disperse the pomegranate peel polyphenol extract in the composite system, thus obtaining an essential oil-polyphenol-cyclodextrin complex. S3. The cruciferous plant glucosinolate enrichment obtained in step S1, the plant-derived black mustard enzyme preparation, the essential oil-polyphenol-cyclodextrin complex, low-methoxyl pectin and erythritol obtained in step S2 are mixed at 25°C, and the moisture content of the mixture is controlled at 11% to inhibit the premature reaction between the glucosinolate enrichment and the plant-derived black mustard enzyme preparation during the preparation process, so as to obtain a water-activated plant-derived food preservative.

[0022] Example 3: The water-activated plant-derived food preservative of this example comprises the following components by weight: 30 parts of cruciferous plant glucosinolate concentrate, 8 parts of plant-derived black mustard enzyme preparation, 15 parts of citrus peel essential oil, 20 parts of pomegranate peel polyphenol extract, 35 parts of low-methoxyl pectin, 45 parts of cyclodextrin derivative, and 3 parts of water activity regulator; wherein, the cruciferous plant glucosinolate concentrate is derived from cabbage seeds, and its glucosinolate content is 5%; the plant-derived black mustard enzyme preparation is derived from cabbage seeds, and its enzyme activity is 500 U / g; the citrus peel essential oil is grapefruit peel essential oil; the total polyphenol content in the pomegranate peel polyphenol extract is 30%; the cyclodextrin derivative is sulfobutyl-β-cyclodextrin; and the water activity regulator is sorbitol.

[0023] The food preservative in this embodiment is prepared using the following steps: S1. Mix cabbage seed raw material with water, inoculate with Lactobacillus casei at an inoculation amount of 108 CFU / g, ferment at 37℃ for 4 h, after fermentation, inactivate enzyme at 120℃ for 2 min, then defatting and water-alcohol extraction at 45℃ to obtain a cruciferous plant glucosinolate enrichment; wherein, the volume fraction of ethanol in the water-alcohol extraction is 80%, and the extraction temperature is 50℃; separately, take cabbage seed raw material, crush it at a temperature not exceeding 35℃, and extract and concentrate it at a temperature not exceeding 40℃ to obtain a plant-derived black mustard enzyme preparation; S2. Mix grapefruit peel essential oil with sulfobutyl-β-cyclodextrin and add pomegranate peel polyphenol extract. Shear the mixture at 15000 r / min for 3 min to combine the citrus peel essential oil with the cyclodextrin derivative and disperse the pomegranate peel polyphenol extract in the composite system to obtain an essential oil-polyphenol-cyclodextrin complex. S3. The cruciferous plant glucosinolate enrichment obtained in step S1, the plant-derived black mustard enzyme preparation, the essential oil-polyphenol-cyclodextrin complex obtained in step S2, low-methoxyl pectin and sorbitol are mixed at 40°C, and the moisture content of the mixture is controlled at 20% to inhibit the premature reaction between the glucosinolate enrichment and the plant-derived black mustard enzyme preparation during the preparation process, so as to obtain a water-activated plant-derived food preservative.

[0024] Comparative Example 1: The difference between this comparative example and Example 1 is that no plant-derived black mustard enzyme preparation is added, while the remaining components and preparation steps are the same as in Example 1.

[0025] Comparative Example 2: The difference between this comparative example and Example 1 is that the glucosinolate enrichment is not subjected to enzyme inactivation treatment, but is directly subjected to low-temperature defatting and water-alcohol extraction; the remaining components, dosages and preparation steps are the same as in Example 1.

[0026] Comparative Example 3: The difference between this comparative example and Example 1 is that in step S3, the moisture content of the mixed system is adjusted to 30%; the remaining components, dosages and preparation steps are the same as in Example 1.

[0027] Performance testing 1 water activity Place an appropriate amount of preservative sample into the sample cup of the water activity meter, ensuring the sample is evenly spread and covers the bottom of the cup, avoiding compaction or contamination of the cup wall. Place the sample cup into the instrument's measuring chamber and equilibrate at 25°C until the instrument reading stabilizes. Record the water activity value. Perform three parallel measurements for each sample and take the average value.

[0028] 2-Glucoside Content Take 1.0 g of preservative sample, add 70% methanol solution for extraction, centrifuge, collect the supernatant, filter through a membrane, and perform HPLC analysis. Establish a standard curve using the corresponding glucosinolate standards, and calculate the glucosinolate content in the sample. Each sample was analyzed in triplicate.

[0029] 3. Isothiocyanate formation upon contact with water Headspace solid-phase microextraction-gas chromatography-mass spectrometry (GC-MS) was used to determine the volatile isothiocyanates generated upon contact with water by preservatives. 1.0 g of preservative sample was placed in a 20 mL headspace vial, 5 mL of sterile water was added, and the vial was immediately sealed. The reaction was carried out at 25 °C for 30 min to allow the glucosinolate concentrate to undergo an enzymatic reaction with a plant-derived black mustard enzyme preparation. Subsequently, headspace solid-phase microextraction was performed using a fiber optic adsorption method for 20 min, followed by GC-MS analysis. An external standard curve was established to calculate the amount of isothiocyanates generated upon contact with water.

[0030] Table 1. Physicochemical properties and water-activated properties of preservative samples

[0031] As shown in Table 1, the water activities of Examples 1-3 were 0.30, 0.43 and 0.58, respectively, which were all at relatively low levels. Meanwhile, the glucosinolate content increased from 41.6 mg / g to 118.7 mg / g with the increase of the effective component dosage. After 30 min of contact with water, the isothiocyanate generation increased from 286.5 μg / g to 936.4 μg / g. This indicates that the present invention, through low-moisture compounding, keeps the glucosinolate enrichment and the plant-derived black mustard enzyme preparation relatively stable during the preparation and storage stages, and effectively undergoes enzymatic reaction after contact with water to generate isothiocyanate antibacterial substances in situ. Comparative Example 1, without the addition of plant-derived black mustard enzyme preparation, showed an isothiocyanate production of only 38.6 μg / g, indicating that the activation ability upon contact with water was significantly insufficient without enzyme catalysis. Comparative Example 2, without enzyme inactivation treatment of the glucosinolate enrichment, resulted in a decrease in its glucosinolate content to 23.8 mg / g, indicating that the precursor was consumed prematurely during the preparation process. Comparative Example 3, without controlling low moisture content, showed a water activity of 0.82, and both the glucosinolate content and isothiocyanate production were lower than in Example 1, indicating that a high moisture environment would cause the precursor to react prematurely with the enzyme, resulting in the loss of active substances.

[0032] 4. Antibacterial properties Escherichia coli, Staphylococcus aureus, yeast, and mold were selected as test subjects. Preservative samples were added to sterile water to prepare sample solutions of 1.0%, 2.0%, and 4.0%, and allowed to stand for 30 min to activate the samples upon contact with water. The activated sample solutions were then mixed with the bacterial suspension at a 1:1 volume ratio to achieve an initial bacterial concentration of approximately 10⁵–10⁶ CFU / mL. After incubation for 0 h, 2 h, 6 h, and 24 h, samples were serially diluted, and the number of surviving bacteria was determined using the plate count method.

[0033] The antibacterial rate is calculated using the following formula: Antibacterial rate = (number of colonies in blank control - number of colonies in sample treatment) / number of colonies in blank control × 100%.

[0034] Table 2 Antibacterial properties of preservative samples

[0035] Table 2 shows that Examples 1-3 all exhibited high inhibition rates against *Escherichia coli*, *Staphylococcus aureus*, yeast, and mold. This indicates that the water-activated system constructed by the present invention using "thioglucosinolate enrichment + plant-derived black mustard enzyme preparation" can generate isothiocyanate-based antibacterial substances in situ upon contact with water, and form a synergistic antibacterial effect with citrus peel essential oil and pomegranate peel polyphenol extract, thereby achieving better bacterial and fungal inhibition effects. Comparative Example 1 did not include plant-derived black mustard enzyme preparation, making it difficult for the thioglucosinolate enrichment to be effectively catalyzed and hydrolyzed, resulting in insufficient isothiocyanate generation and a significantly lower inhibition rate than Example 1. Comparative Example 2 did not perform enzyme inactivation treatment on the thioglucosinolate enrichment, making it prone to premature reaction of the endogenous black mustard enzyme in the raw materials during extraction, mixing, or storage, leading to the loss of active precursors and a decrease in water-activated capacity during use. Comparative Example 3 increased the moisture content of the mixed system to 30%, causing the glucosinolate enrichment and black mustard enzyme preparation to undergo an enzymatic reaction earlier during the preparation stage, resulting in the premature generation and volatilization of isothiocyanate. Therefore, its antibacterial performance was lower than that of Example 1.

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A water-activated plant-derived food preservative, characterized by comprising a plant-derived material and a water-soluble polymer. The product comprises, by weight, the following components: 8-30 parts of cruciferous plant glucosinolate concentrate, 1-8 parts of plant-derived black mustard enzyme preparation, 3-15 parts of citrus peel essential oil, 5-20 parts of pomegranate peel polyphenol extract, 10-35 parts of low-methoxyl pectin, 15-45 parts of cyclodextrin derivative, and 3-18 parts of water activity regulator; wherein the cruciferous plant glucosinolate concentrate and the plant-derived black mustard enzyme preparation undergo an enzymatic reaction in the presence of water to generate isothiocyanate antibacterial substances.

2. The water-activated plant-derived food preservative according to claim 1, characterized in that, The brassicaceae plant glucosinolate enrichment is derived from one or more of mustard seeds, radish seeds, broccoli seeds, cabbage seeds, and rapeseed; the glucosinolate content in the brassicaceae plant glucosinolate enrichment is not less than 5%.

3. The water-activated plant-derived food preservative according to claim 1, characterized in that, The brassicaceae plant glucosinolate enrichment is a plant extract with low myrosinase activity, and its endogenous myrosinase activity is less than 10 U / g.

4. The water-activated plant-derived food preservative according to claim 1, characterized in that, The plant-derived black mustard enzyme preparation is derived from one or more of mustard seeds, radish seeds, broccoli seeds, cabbage seeds, and rapeseed; the enzyme activity of the plant-derived black mustard enzyme preparation is 10-500 U / g.

5. The water-activated plant-derived food preservative according to claim 1, characterized in that, The citrus peel essential oil is one or more of sweet orange peel essential oil, lemon peel essential oil, grapefruit peel essential oil, and bergamot essential oil; the total polyphenol content of the pomegranate peel polyphenol extract is not less than 30%.

6. The water-activated plant-derived food preservative according to claim 1, characterized in that, The cyclodextrin derivative is one or more of hydroxypropyl-β-cyclodextrin, methyl-β-cyclodextrin, and sulfobutyl-β-cyclodextrin; the water activity regulator is one or more of trehalose, erythritol, sorbitol, glycerol, and maltodextrin.

7. A method for preparing a water-activated plant-derived food preservative as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. The cruciferous plant raw material is subjected to enzyme inactivation treatment at 80-120℃ for 2-15 min, followed by low-temperature defatting and water-alcohol extraction to obtain a cruciferous plant glucosinolate enrichment; the cruciferous plant raw material is further crushed, extracted and concentrated under low-temperature conditions to obtain a plant-derived black mustard enzyme preparation. S2. Mix citrus peel essential oil with cyclodextrin derivatives and add pomegranate peel polyphenol extract. Shear the mixture at 6000-15000 r / min for 3-15 min to obtain essential oil-polyphenol-cyclodextrin complex. S3. The cruciferous plant glucosinolate enrichment obtained in step S1, the plant-derived black mustard enzyme preparation, the essential oil-polyphenol-cyclodextrin complex obtained in step S2, the low-methoxyl pectin and the water activity regulator are mixed at 15-40℃ to obtain a water-activated plant-derived food preservative.

8. The preparation method according to claim 7, characterized in that, In step S1, when preparing the cruciferous plant glucosinolate enrichment, the low-temperature defatting temperature is 20-45℃; the volume fraction of ethanol in the water-alcohol extraction is 30%-80%, and the extraction temperature is not higher than 50℃.

9. The preparation method according to claim 7, characterized in that, In step S1, when preparing the plant-derived black mustard enzyme preparation, the pulverization temperature is not higher than 35℃ and the extraction temperature is not higher than 40℃; in step S3, the moisture content of the mixed system is controlled at 3-20% to inhibit the premature reaction between the cruciferous plant glucosinolate enrichment and the plant-derived black mustard enzyme preparation during the preparation process.

10. The preparation method according to claim 7, characterized in that, The cruciferous plant raw material undergoes fermentation pretreatment before enzyme inactivation: the cruciferous plant raw material is mixed with water, inoculated with lactic acid bacteria at an inoculation amount of 10⁵–10⁸ CFU / g, and fermented at 25–37°C for 4–24 h. After fermentation, enzyme inactivation is performed to obtain fermentation pretreatment raw material for preparing cruciferous plant glucosinolate enrichment. The lactic acid bacteria are one or more of Lactobacillus plantarum, Lactobacillus rhamnosus, and Lactobacillus casei.

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