Method for prolonging shelf life of chilled meat, removing fishy smell and enhancing aroma by using plant essential oil inclusion emulsion

Abstract

The invention belongs to the technical field of food preservation, and relates to a method for prolonging the shelf life of chilled meat, removing fishy smell and enhancing aroma by using a plant essential oil clathration emulsion, and a preparation method of the plant essential oil clathration emulsion comprises the following steps: uniformly mixing plant essential oil with a co-emulsifier to obtain an essential oil mixed solution; the preparation method comprises the following steps: dissolving starch with water to prepare a starch aqueous solution, adding beta-CGT enzyme and debranching enzyme to carry out liquefaction reaction, then adding essential oil mixed liquor and beta-cyclodextrin glycosyl transferase, uniformly mixing, cyclizing, adding an emulsifier in the cyclizing process, and shearing and homogenizing after cyclizing to obtain the plant essential oil inclusion emulsion. The plant essential oil inclusion emulsion is applied to fresh keeping of meat products, and the plant essential oil with extremely low concentration is used for effectively inhibiting the increase of the total number of bacterial colonies of the meat products, delaying the increase of pH and volatile basic nitrogen and inhibiting the reduction of sensory scores of the meat products. The prepared plant essential oil clathrate emulsion is high in stability and is applied to fresh keeping of meat products after being placed at room temperature for 7 days, and the fresh keeping effect is basically not deteriorated.

Description

Technical Field

[0001] The invention relates to a method for extending the shelf life of fresh meat and removing fishy smell and enhancing fragrance by utilizing plant essential oil inclusion emulsion, and belongs to the technical field of food preservation. Background Art

[0002] Chilled meat refers to fresh meat that is kept at 0-4℃ during production, processing, circulation and distribution, and is one of the main sales forms in the meat market. Since chilled meat contains high levels of nutrients such as water and unsaturated fatty acids, its quality is easily degraded or even spoiled even when stored at low temperatures.

[0003] In order to maintain the quality of meat and delay the spoilage of meat, certain technical means need to be adopted to inhibit the growth of microorganisms. Chemical preservation has been widely used to extend the shelf life of fresh meat due to its low cost and small dosage. However, the use of chemical preservatives is limited due to their residual risks and toxic side effects. Although physical preservation is safe, the equipment cost is high, it has strict requirements on the environment, and the preservation effect is limited.

[0004] As consumers pay more and more attention to food safety, biological preservation technology is a hot topic in the current preservation field. Natural plant essential oils have attracted widespread attention due to their good antioxidant and antibacterial properties. A patent application with publication number CN115812768A discloses a composite essential oil for pork preservation. The composite essential oil is prepared by diluting an essential oil stock solution with an anhydrous ethanol diluent. The volume ratio of the essential oil stock solution to anhydrous ethanol is 12:112. Using it as a meat preservative can extend the shelf life of meat products. However, the poor stability and high volatility of plant essential oils can lead to a decrease in sensory quality and cost loss due to the pungent odor, which will be limited in practical application.

[0005] In order to reduce the odor impact of plant essential oils and reduce the cost losses caused by their volatility, they are often used in a packaged form.

[0006] Common wall materials include cyclodextrin, chitosan, sodium alginate, protein and polysaccharide composite wall materials, etc. "Preparation of sodium alginate-chitosan modified cinnamon essential oil liposomes and their application in chilled fresh pork" discloses a method of applying sodium alginate-chitosan double-layer modified cinnamon essential oil liposomes to preserve chilled fresh pork. However, the preparation of liposomes requires steps such as rotary evaporation film formation and ultrasonic hydration, which requires high equipment, is time-consuming and costly to operate. Cyclodextrin encapsulation usually only requires mixing or stirring, has low equipment requirements, and is more suitable for large-scale production. At the same time, liposomes are susceptible to oxidation, aggregation or phase separation, and long-term storage requires the addition of antioxidants or low-temperature storage. Due to the physical isolation of the molecular cavity, cyclodextrin inclusion complexes have better protection against oxidation and volatilization, and their stability is significantly improved.

[0007] Although cyclodextrin is highly stable, it has the problem of high cost. Most of the literature on essential oil inclusion uses saturated aqueous solution method, ultrasonic resonance method, and solid-liquid method, without considering the high cost of cyclodextrin production and purification. Therefore, some studies have carried out the cyclodextrin production process and the inclusion process simultaneously.

[0008] "Efficient formation of carvacrol inclusion complexes during βcyclodextrin glycosyltransferase-catalyzed cyclodextrin synthesis" discloses a technical method for simultaneously encapsulating carvacrol during the enzymatic synthesis of cyclodextrin and spray drying to obtain microcapsules. "Cyclodextrin glycosyltransferase-catalyzed products from starch enhance the stability of microencapsulated cinnamaldehyde emulsion" also discloses a technical means for preparing microencapsulated cinnamaldehyde emulsion by combining the inclusion of cyclodextrin glycosyltransferase-catalyzed products with emulsion embedding technology. The two methods of encapsulating plant essential oils greatly reduce production costs, but when only CGT enzyme is used to prepare cyclodextrin, the liquefaction reaction may not be sufficient, resulting in the presence of more oligomers and dextrin-like substances in the prepared finished product in addition to cyclodextrin. Therefore, in this preparation process, more cyclization sites are exposed by using dual enzymes or multiple enzymes to generate more cyclodextrin wall materials, which greatly improves the inclusion rate. Summary of the invention

[0009]

Technical issues

[0010] Plant essential oils with antibacterial and fresh-keeping effects have a pungent smell, affect the flavor of meat products, are highly volatile, and have high losses during actual use. They are usually included to reduce the pungent smell and volatility losses. However, the existing plant essential oil inclusion methods are costly, unstable, and have high essential oil losses. The preservation effect of the prepared plant essential oil inclusion products on meat products needs to be improved.

[0011]

Technical solution

[0012] The first object of the present invention is to provide a method for preparing a plant essential oil inclusion emulsion with a low essential oil concentration, comprising the steps of:

[0013] (1) Preparation of essential oil mixture: uniformly mixing plant essential oil and co-emulsifier to obtain essential oil mixture;

[0014] (2) Enzymatic production of cyclodextrin: β-cyclodextrin glycosyltransferase (β-CGTase) and debranching enzyme are added to the starch aqueous solution for liquefaction reaction, and then the essential oil mixture and β-cyclodextrin glycosyltransferase are added, mixed evenly, and a cyclization reaction is carried out. An emulsifier is added during the cyclization process;

[0015] (3) Preparation of plant essential oil inclusion emulsion: Shear and homogenize the plant essential oil inclusion solution to obtain the plant essential oil inclusion emulsion.

[0016] In one embodiment of the present invention, in step (1), the plant essential oil is selected from one or more of cinnamaldehyde, citral, carvacrol, thymol and eugenol.

[0017] In one embodiment of the present invention, in step (1), the plant essential oil is preferably carvacrol and cinnamaldehyde; and the volume ratio of carvacrol to cinnamaldehyde is preferably 1:1.

[0018] In one embodiment of the present invention, in step (1), the co-emulsifier is anhydrous ethanol; the amount of the co-emulsifier is 10% to 25% of the volume of the plant essential oil.

[0019] In one embodiment of the present invention, in step (2), the starch is selected from one or more of wheat starch, corn starch, potato starch and tapioca starch.

[0020] In one embodiment of the present invention, in step (2), the starch concentration of the starch aqueous solution is 1 to 5 wt %; and the amount of the plant essential oil used is 10 to 15% of the mass of the starch.

[0021] In one embodiment of the present invention, in step (2), the β-cyclodextrin glycosyltransferase is derived from Bacillus circulans STB01.

[0022] In one embodiment of the present invention, in step (2), the amount of β-cyclodextrin glycosyltransferase added each time is 1 U / g to 4 U / g relative to starch.

[0023] In one embodiment of the present invention, in step (2), the debranching enzyme is selected from one or more of pullulanase, isoamylase and dextrin debranching enzyme.

[0024] In one embodiment of the present invention, in step (2), the amount of the added debranching enzyme relative to starch is 0.2 U / g to 1 U / g.

[0025] In one embodiment of the present invention, in step (2), the conditions of the liquefaction reaction are: reaction at a temperature of 85 to 95° C. for 20 to 40 minutes; and a liquefaction rotation speed of 200 to 500 rpm.

[0026] In one embodiment of the present invention, in step (2), the conditions for the cyclization reaction are: reaction at a temperature of 45 to 55° C. for 10 to 14 hours; and a cyclization speed of 200 to 500 rpm.

[0027] In one embodiment of the present invention, in step (2), an emulsifier is added during the cyclization period of 0.5 to 1.5 hours.

[0028] In one embodiment of the present invention, in step (2), the emulsifier is selected from one or more of Tween 80, soy protein, and monoglyceride; the amount of the emulsifier is 5-20% of the total mass of starch and plant essential oil.

[0029] In one embodiment of the present invention, in step (3), the shearing speed is 8000 rpm to 12000 rpm, and the shearing time is 1 min to 3 min.

[0030] In one embodiment of the present invention, in step (3), the homogenization pressure is 40-50 bar, the homogenization times are 3-5 times, and the homogenization temperature is 2-8°C.

[0031] The second object of the present invention is to provide the plant essential oil inclusion emulsion prepared by the above preparation method.

[0032] The third object of the present invention is to provide the use of the above-mentioned plant essential oil inclusion emulsion in the preservation of fresh cold meat.

[0033] In one embodiment of the present invention, the meat is livestock meat, poultry meat and aquatic products.

[0034] The fourth object of the present invention is to provide a method for preserving fresh cold meat using the plant essential oil inclusion emulsion, comprising the steps of: soaking the meat in the plant essential oil inclusion emulsion, taking it out and refrigerating it at 0-4°C.

[0035] In one embodiment of the present invention, the meat is cut into pieces of 25 to 100 g.

[0036] In one embodiment of the present invention, the soaking time is 10 to 30 minutes.

[0037] Beneficial effects:

[0038] The raw materials of the plant essential oil inclusion emulsion of the present invention are easily available, safe and non-toxic, and the preparation process is simple, and industrial production can be easily realized, thereby avoiding the problem of high production and purification costs of cyclodextrin.

[0039] The plant essential oil inclusion emulsion of the present invention contains very little plant essential oil (less than 0.1 g / 100 mL), which significantly masks the pungent smell of the plant essential oil and reduces the cost. As a preservative, the plant essential oil can be used in cold fresh meat products to significantly extend the shelf life and shelf life of the cold fresh meat products with extremely low concentrations of plant essential oils. There is no report in the prior art on achieving excellent meat product preservation effects with low essential oil concentration emulsions. The two plant essential oils, carvacrol and cinnamaldehyde, are used to synergistically improve the meat product preservation effect.

[0040] The present invention creatively uses double enzymes or multiple enzymes to prepare more cyclodextrins to include more plant essential oils, successfully prolongs the use time of the preservative, and reduces substrate waste in the preparation process.

[0041] Compared with meat products coated with essential oils, the plant essential oil inclusion emulsion of the present invention achieves a better preservation effect with a very small amount of essential oil, and the color and flavor of the meat products are more acceptable.

[0042] The plant essential oil inclusion emulsion of the present invention is used as a preservative in fresh meat products, has high biological safety, effectively inhibits the growth of the total number of colonies of meat products, delays the increase of pH and volatile basic nitrogen, effectively inhibits the decrease of sensory scores of meat products, and plays a role in removing fishy smell and enhancing flavor for fresh meat. The total number of colonies of untreated meat products exceeds the national standard (total number of colonies>10 6 CFU / g is spoiled meat), and its pH value and volatile basic nitrogen exceed the national standard after refrigerated storage for 10 days (pH>6.2 is not fresh meat, and volatile basic nitrogen>150mg / kg is spoiled meat). The total bacterial count of the meat product treated with the plant essential oil inclusion emulsion of the present invention exceeds the national standard after refrigerated storage for 7 days, and the pH value and volatile basic nitrogen exceed the national standard after refrigerated storage for 14 days, which significantly extends the refrigerated storage period of the meat product.

[0043] The present invention includes plant essential oils to improve the defects of plant essential oils being volatile and insoluble in water, thereby greatly reducing the cost and loss in production. The prepared plant essential oil inclusion emulsion has high stability. The preservative prepared by using two or more enzymes in an enzymatic reaction has a better preservative effect than that prepared by using a single enzyme for enzymatic reaction under the same conditions, and has a better effect as a preservative after being placed at room temperature for 7 days, and can still more effectively inhibit the growth of the total number of colonies of fresh meat, delay the increase of pH and volatile basic nitrogen, and inhibit the decrease of sensory scores of meat products. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The sensory evaluation results of Examples 1 and 5 and Comparative Examples 1, 2, 3 and 4 are shown.

[0045] Figure 2It is a comparison chart of untreated lean meat and lean meat treated with pure essential oil at 0 d and 7 d of storage (cut surface). Detailed implementation method

[0046] The materials involved in the following examples and comparative examples are as follows:

[0047] β-CGT enzyme is derived from Bacillus circulans STB01. The debranching enzymes are all commercially available. The chilled fresh meats are all commercially available. The plant essential oil is purchased from Guangdong Daily Chemical Industry Co., Ltd.

[0048] The detection methods involved in the following examples and comparative examples are as follows:

[0049] Total colony count detection: It is determined according to GB4789.2-2022.

[0050] pH value: It is detected by using a Simma PH818M pH tester.

[0051] Volatile basic nitrogen value: It is measured by using a volatile basic nitrogen detection reagent. The test method is as follows:

[0052] i. Weigh 2 g of the chilled fresh meat sample, crush it in a sample cup, add 20 mL of distilled water, and soak for 10 - 15 min.

[0053] ii. Pipette 1 mL of the supernatant of the sample extract into a detection tube, add 2 drops of the detection liquid to the detection tube, and shake well.

[0054] iii. Observe the color development situation within 2 min, and record the volatile basic nitrogen content by referring to the volatile basic nitrogen standard colorimetric card. According to the provisions of GB 2707: The volatile basic nitrogen content of fresh (frozen) livestock and poultry products should be ≤ 150 mg / kg.

[0055] Sensory evaluation: Select 10 food professional students with sensitive taste and smell to form a sensory evaluation group, and conduct sensory evaluation on the color, flavor, and texture state of the meat product samples. Each sample is evaluated within 15 min. The sensory scoring criteria are shown in Table 1, and the total score evaluation criteria are shown in Table 2.

[0056] Table 1 Sensory scoring criteria for meat products

[0057]

[0058] Table 2 Total score evaluation criteria

[0059] evaluate excellent middle Difference Score area 23-30 minutes 15-22 minutes Less than 15 points

[0060] Example 1

[0061] A method for preserving chilled fresh meat with a plant essential oil inclusion emulsion with a low essential oil concentration, including the steps:

[0062] (1) Preparation of essential oil mixture: 500 μL of carvacrol and 500 μL of cinnamaldehyde were mixed, and then 250 μL of anhydrous ethanol was added and mixed evenly to obtain an essential oil mixture;

[0063] (2) Enzymatic production of cyclodextrin: 2 g (dry basis) corn starch was dissolved in water to prepare a starch aqueous solution, so that the starch concentration of the starch aqueous solution was 1 wt %, 2 U / g of β-CGTase and 0.5 U / g of pullulanase were added, and liquefied at 90° C. and 300 rpm for 30 min, and then 2 U / g of β-CGTase was added, followed by 250 μL of essential oil mixture, so that the mass of plant essential oil was 10% of the mass of starch, and cyclized at 50° C. and 300 rpm. After cyclization for 1 h, 0.11 g of Tween 80 was added, so that the mass of Tween 80 was 5% of the total mass of starch and plant essential oil. The total cyclization time was 12 h, and a plant essential oil inclusion solution was obtained;

[0064] (3) Preparation of plant essential oil inclusion emulsion: The plant essential oil inclusion solution was sheared at 10000 rpm for 1 min, and homogenized three times at 4° C. and 40 bar to obtain the plant essential oil inclusion emulsion;

[0065] (4) Cut fresh pork into 30 g pieces, soak them in the plant essential oil encapsulated emulsion for 20 min, then take them out and refrigerate them at 4°C.

[0066] Example 2

[0067] The only difference from Example 1 is that in step (2), the starch concentration of the starch aqueous solution is 5wt%, and the essential oil mixture is added so that the mass of the plant essential oil is 15% of the mass of the starch.

[0068] Example 3

[0069] The only difference from Example 1 is that the plant essential oil inclusion emulsion prepared in step (3) is stored at room temperature for 7 days before step (4) is performed.

[0070] Example 4

[0071] The only difference from Example 2 is that the plant essential oil inclusion emulsion prepared in step (3) is stored at room temperature for 7 days before step (4) is performed.

[0072] Comparative Example 1

[0073] Fresh, unprocessed pork.

[0074] Comparative Example 2

[0075] Fresh pork was cut into 30 g pieces, carvacrol and cinnamaldehyde were mixed in a volume ratio of 1:1, and applied on the surface of the fresh pork. The ratio of plant essential oil to meat product was 10 μL / g.

[0076] Comparative Example 3

[0077] The only difference from Example 1 is that the plant essential oil used is carvacrol.

[0078] Comparative Example 4

[0079] The difference from Example 1 is that the plant essential oil used is cinnamaldehyde.

[0080] Comparative Example 5

[0081] The only difference from Example 1 is that pullulanase was not used.

[0082] Comparative Example 6

[0083] The only difference from Comparative Example 5 is that the plant essential oil inclusion emulsion prepared in step (3) is stored at room temperature for 7 days before step (4) is performed.

[0084] Example 5

[0085] The only difference from Example 1 is that in step (4), fresh pork is replaced with fresh chicken breast.

[0086] Example 6

[0087] The only difference from Example 2 is that in step (4), fresh pork is replaced with fresh chicken breast.

[0088] Example 7

[0089] The only difference from Example 3 is that in step (4), fresh pork is replaced with fresh chicken breast.

[0090] Example 8

[0091] The only difference from Example 4 is that in step (4), fresh pork is replaced with fresh chicken breast.

[0092] Comparative Example 7

[0093] Fresh, untreated chicken breast.

[0094] Comparative Example 8

[0095] The only difference from Comparative Example 2 is that the fresh pork is replaced with fresh chicken breast.

[0096] Comparative Example 9

[0097] The only difference from Example 5 is that the plant essential oil used is carvacrol.

[0098] Comparative Example 10

[0099] The difference from Example 5 is that the plant essential oil used is cinnamaldehyde.

[0100] Comparative Example 11

[0101] The only difference from Example 5 is that pullulanase was not used.

[0102] Comparative Example 12

[0103] The only difference from Example 5 is that the plant essential oil inclusion emulsion prepared in step (3) is stored at room temperature for 7 days before step (4) is performed.

[0104] The sensory scores of lean meat and chicken breast meat during refrigerator storage vary with storage time. Figure 1 The sensory evaluation results of the meat products of Example 1 and Example 5 during the storage period are better than those of the untreated group (Comparative Examples 1 and 7), indicating that the plant essential oil inclusion emulsion has the effect of extending the shelf life of meat products; in Comparative Examples 2 and 8, although the pure essential oil as a preservative can slow down the decline in the quality of meat products, the quality of meat products has obviously declined at the beginning of the storage period, indicating that the direct action of pure essential oil on meat products will cause serious damage to the quality of meat products and is not suitable for use as a preservative.

[0105] The changes in the total number of bacterial colonies in lean meat and chicken breast during refrigerator storage with storage time are shown in Table 3.

[0106] Table 3 Changes in total colony counts in meat samples during storage in different treatment groups (unit: 10 5 CFU / g)

[0107]

[0108]

[0109] During the 10-day refrigerated storage, the changes in the total bacterial counts of the meat products obtained in Examples 1, 3, 5, 7 and Examples 2, 4, 6, and 8 slowed down during the refrigerated storage process, and all of them did not exceed the national standard (total bacterial count>10) until 7 days. 6 CFU / g is spoiled meat), and comparative examples 1 and 7 both exceeded the national standard in 3 days. This shows that after treatment with low-concentration plant essential oil inclusion preservative, the antibacterial effect is obvious, and the preservative effect does not decrease significantly after being placed at room temperature for 7 days, indicating that inclusion can effectively stabilize and slowly release plant essential oils.

[0110] Compared with Example 1, the total colony count of Comparative Examples 3 and 4 grew slightly faster, and exceeded the national standard on the 6th day; compared with Example 5, the total colony count of Comparative Examples 9 and 10 grew slightly faster, and exceeded the national standard on the 6th day; it shows that the preservative containing two plant essential oils can better inhibit the growth of the total colony count than the preservative containing a single essential oil, and has a synergistic effect; compared with Example 1, Comparative Example 5 exceeded the national standard at 5 days, and Comparative Example 6 exceeded the national standard at 4 days; compared with Example 5, Comparative Example 11 exceeded the national standard at 5 days, and Comparative Example 12 exceeded the national standard at 4 days; it shows that the preparation of cyclodextrin can fully react by using a double enzyme in the liquefaction process to improve the inclusion rate of the plant essential oil, so that after being placed at room temperature for 7 days, the preservation effect of the plant essential oil inclusion emulsion preservative remains basically unchanged, and although only a single enzyme has a preservation effect, the effect is poor after being placed for 7 days.

[0111] Table 4 Changes in pH of meat samples during storage in different treatment groups

[0112]

[0113]

[0114] As the storage time increases, the microorganisms and some endogenous proteases in the meat degrade the protein into volatile alkaline nitrogen-containing substances, causing the pH value of pork to increase. From Table 4, it can be found that the pH changes in Examples 1, 2, 5 and 6 are the slowest, and it is not until 14 days that it exceeds the national standard (pH>6.2 is not fresh meat), Comparative Example 1 exceeds the national standard at 10 days, and Comparative Example 7 exceeds the national standard at 9 days; Examples 3 and 4 have no obvious difference from Examples 1 and 2, respectively, and exceed the national standard at 14 days; Examples 7 and 8 have no obvious difference from Examples 5 and 6, respectively, and exceed the national standard at 13 days; It shows that after being treated with a low-concentration plant essential oil inclusion preservative, the pH change of cold fresh meat is significantly slowed down, and the preservative effect is not significantly reduced after being placed at room temperature for 7 days, indicating that inclusion can effectively stabilize and slowly release plant essential oils.

[0115] The pH of Comparative Examples 3 and 4 increased slightly faster than that of Example 1, and exceeded the national standard in 12 days. The pH of Comparative Examples 9 and 10 increased slightly faster than that of Example 5, and exceeded the national standard in 12 days, indicating that the preservative containing two plant essential oils can slow down the increase in pH of fresh meat better than the preservative containing a single essential oil, and has a synergistic effect.

[0116] Compared with Example 1, Comparative Example 5 exceeded the national standard at 10 days, and Comparative Example 6 exceeded the national standard at 9 days; compared with Example 5, Comparative Example 11 exceeded the national standard at 11 days, and Comparative Example 12 exceeded the national standard at 10 days; it indicates that the preparation of cyclodextrin can fully react by using two enzymes in combination during the liquefaction process to improve the inclusion rate of the plant essential oil, so that after being placed at room temperature for 7 days, the preservation effect of the plant essential oil inclusion emulsion preservative remains basically unchanged, and although there is a fresh effect using only a single enzyme, the effect is poor after being placed for 7 days.

[0117] Table 5 Changes in volatile basic nitrogen in meat samples during storage in different treatment groups (unit: mg / kg)

[0118]

[0119] The generation of volatile basic nitrogen is closely related to the decomposition of protein in food. The content of volatile basic nitrogen in fresh food is low, and the content will increase significantly with the storage time. From Table 5, it can be found that the changes in volatile basic nitrogen in Examples 1, 2, 3, and 4 have slowed down, and it was not until 14 days that it exceeded the national standard (volatile basic nitrogen>150mg / kg is spoiled meat), and Comparative Example 1 exceeded the national standard at 10 days; the volatile basic nitrogen in Examples 5, 6, 7, and 8 still did not completely exceed the national standard at 14 days, and Comparative Example 7 exceeded the national standard at 10 days; it shows that after being treated with a low-concentration plant essential oil inclusion preservative, the increase of volatile basic nitrogen in cold fresh meat has been significantly slowed down, and the preservative has no significant reduction in freshness after being placed at room temperature for 7 days, indicating that inclusion can effectively stabilize and slowly release plant essential oils;

[0120] Comparative Examples 3 and 4 exceeded the national standard at 13 days, and Comparative Examples 9 and 10 exceeded the national standard at 13 days, indicating that the preservative containing pure plant essential oils is slightly inferior to the preservative effect of the compound essential oil, and the increase of volatile basic nitrogen is faster, which verifies that the use of the compound essential oil has a certain synergistic effect.

[0121] Comparative Examples 5 and 11 exceeded the national standard at 12 days, and Comparative Examples 6 and 12 exceeded the national standard at 11 days; this indicates that the preparation of cyclodextrin can fully react through the combined use of two enzymes in the liquefaction process to improve the plant essential oil inclusion rate, so that after being placed at room temperature for 7 days, the preservation effect of the plant essential oil inclusion emulsion preservative remains basically unchanged. Although only a single enzyme has a preservation effect, the effect is poor after being placed for 7 days.

[0122] In the plant essential oil inclusion emulsions of Examples 1, 3, 5, and 7 of the present invention, the essential oil concentration is less than 0.1 g / 100 mL, and when used for meat product preservation, the total bacterial count of the treated meat product exceeds the national standard after refrigerated storage for 7 days, and the pH value and volatile basic nitrogen exceed the national standard after refrigerated storage for 14 days. There is no report in the prior art on achieving excellent meat product preservation effect using an emulsion with a low essential oil concentration.

[0123] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a plant essential oil inclusion emulsion with low essential oil concentration, characterized in that: Includes steps: (1) Preparation of essential oil mixture: uniformly mixing plant essential oil and co-emulsifier to obtain essential oil mixture; (2) Enzymatic production of cyclodextrin: adding β-cyclodextrin glycosyltransferase and debranching enzyme to a starch aqueous solution for liquefaction reaction, then adding an essential oil mixture and β-cyclodextrin glycosyltransferase, mixing evenly, and performing a cyclization reaction to obtain a plant essential oil inclusion solution; adding an emulsifier during the cyclization process; (3) Preparation of plant essential oil inclusion emulsion: Shear and homogenize the plant essential oil inclusion solution to obtain the plant essential oil inclusion emulsion.

2. The preparation method according to claim 1, characterized in that: In step (1), the plant essential oil is selected from one or more of cinnamaldehyde, citral, carvacrol, thymol, and eugenol; the auxiliary emulsifier is anhydrous ethanol; and the amount of the auxiliary emulsifier is 10% to 25% of the mass of the plant essential oil.

3. The preparation method according to claim 1, characterized in that: In step (2), the starch is selected from one or more of wheat starch, corn starch, potato starch, and cassava starch; the emulsifier is selected from one or more of Tween 80, soy protein, and monoglycerides; the starch concentration of the starch aqueous solution is 1 to 5 wt%; the amount of the plant essential oil is 10 to 15% of the mass of the starch in the starch aqueous solution; the amount of the emulsifier is 5 to 20% of the total mass of the starch and the plant essential oil; the amount of the β-cyclodextrin glycosyltransferase added each time is 1 U / g to 4 U / g relative to the starch; and the amount of the debranching enzyme added is 0.2 U / g to 1 U / g relative to the starch.

4. The preparation method according to claim 1, characterized in that: In step (2), the conditions for the liquefaction reaction are: reaction at a temperature of 85 to 95° C. for 20 to 40 minutes; the conditions for the cyclization reaction are: reaction at a temperature of 45 to 55° C. for 10 to 14 hours.

5. The preparation method according to claim 1, characterized in that: In step (2), the β-cyclodextrin glycosyltransferase is derived from Bacillus circulans STB01; and the debranching enzyme is selected from one or more of pullulanase, isoamylase and dextrin debranching enzyme.

6. The preparation method according to claim 1, characterized in that: In step (2), an emulsifier is added during the cyclization period of 0.5 to 1.5 hours.

7. The preparation method according to claim 1, characterized in that: In step (3), the shearing speed is 8000 rpm to 12000 rpm, the shearing time is 1 min to 3 min, the homogenization pressure is 40 to 50 bar, the homogenization times are 3 to 5 times, and the homogenization temperature is 2 to 8°C.

8. The plant essential oil inclusion emulsion prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the plant essential oil inclusion emulsion according to claim 8 in the preservation of fresh cold meat.

10. A method for preserving fresh cold meat using the plant essential oil inclusion emulsion according to claim 8, characterized in that: The method comprises the following steps: soaking the meat in the plant essential oil inclusion emulsion, taking out the meat and refrigerating the meat at 0-4°C.

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