Vacuum freeze drying technology applied to food processing

Abstract

The invention relates to the technical field of food preservation, and particularly discloses a vacuum freeze drying technology applied to food processing. The invention relates to a preparation method of a vacuum freeze drying technology applied to food processing. The preparation method comprises the following steps: sorting, cleaning and cutting food raw materials; performing blanching, pre-cooling and water filtering procedures to obtain food to be frozen; preparing a preservative; the method comprises the following steps: soaking to-be-frozen food in a preservative, and carrying out vacuum freeze drying on the to-be-frozen food; and packaging the vacuum freeze-dried food, and warehousing and refrigerating. The preservative comprises the following raw materials: 6-8 g of silicon dioxide loaded modified lemon peel essential oil, 2-4 g of sodium phytate and 8-10 ml of deionized water. The silicon dioxide loaded modified lemon peel essential oil is prepared by loading modified lemon peel essential oil on the surface of silicon dioxide, and hydrophilic groups are introduced into the modified lemon peel essential oil. The vacuum freeze drying technology applied to food processing has the advantage that the defect that the antibacterial property is still insufficient when the lemon slice essential oil is applied to the preservative can be overcome.

Description

Technical Field

[0001] The present application relates to the technical field of food preservation, and more specifically, to a vacuum freeze-drying technology applied to food processing. Background Art

[0002] As human society has developed to date, the world's population of more than 5 billion consumes nearly 2 billion tons of plant and animal food each year. Many foods are preserved by freezing and refrigeration, and the more developed the economy, the greater the amount of freezing and refrigeration. Some developed countries have even begun to preserve grain by refrigeration. Modern industry has combined the freezing and refrigeration of food into a cold chain system: from urbanized freezing and refrigeration processing industries to food refrigerated transport vehicles and refrigerated containers, to shopping mall freezers, and even to household freezers and refrigerators. Human beings are enjoying the advantages that modern industry has brought to their lives.

[0003] Vacuum freeze-drying technology is a drying technology that freezes food in a solid state at a relatively low temperature, and then sublimates the water in the food directly into a gas state without passing through a liquid state under a vacuum, ultimately dehydrating the material. In the existing vacuum freeze-drying method, the food to be frozen is soaked in a preservative during the food freezing process to preserve its nutrients to the maximum extent.

[0004] At present, lemon peel essential oil is widely used in food preservatives due to its antibacterial and other functions. However, the instability of lemon peel essential oil makes it easy to volatilize, which can easily affect the antibacterial properties of lemon peel essential oil after vacuum freeze-drying of food. Summary of the invention

[0005] In order to improve the defect that the antibacterial performance of lemon slice essential oil is still insufficient when used in preservatives, the present application provides a vacuum freeze-drying technology for food processing.

[0006] The present application provides a vacuum freeze-drying technology for food processing, which adopts the following technical solution:

[0007] A vacuum freeze-drying technology applied to food processing comprises the following steps:

[0008] S1: Arrange, clean and cut food ingredients;

[0009] S2: blanching, precooling and water filtering the food in S1 to obtain the food to be frozen;

[0010] S3: prepare preservative;

[0011] S4: placing the food to be frozen in S2 into the preservative in S3 for soaking, and performing vacuum freeze drying on the food;

[0012] S5: Packing the vacuum freeze-dried food and storing it in a cold warehouse;

[0013] The preservative in S2 comprises the following raw materials: 6-8 g of silica-loaded modified lemon peel essential oil, 2-4 g of sodium phytate and 8-10 ml of deionized water;

[0014] The silica-loaded modified lemon peel essential oil is a modified lemon peel essential oil loaded on the surface of silica, and a hydrophilic group is introduced into the modified lemon peel essential oil.

[0015] Since the right-handed limonene contained in the modified lemon peel essential oil has a simple structure, it is easily decomposed under the influence of oxidation, light or temperature changes, and the volatile compounds in the modified lemon peel essential oil are easily converted from liquid to gas, resulting in the volatility of the essential oil. Since the silica-loaded modified lemon peel essential oil used in this application is the modified lemon peel essential oil loaded on the surface of silica, silica has non-toxic and tasteless, is environmentally friendly, absorbs ultraviolet rays, and has stable physical and chemical properties and is used as a carrier for a variety of drugs or active substances. Therefore, silica, as an inert carrier, can protect the active ingredients in the modified lemon peel essential oil from the influence of the external environment, and the modified lemon The volatile components in the lemon peel essential oil reduce the possibility of volatilization and oxidative decomposition, and the microporous structure of silica can serve as an adsorbent for lemon peel essential oil, helping the modified lemon peel essential oil molecules to adhere to its surface, thereby reducing the amount of essential oil volatilized into the air, which is beneficial to improving the stability of the modified lemon peel essential oil and reducing the volatility of the lemon peel essential oil. Since the interaction between the volatile components in the modified lemon peel essential oil and water molecules is weak, it is difficult to dissolve in water. The introduction of hydrophilic groups to improve the water solubility of the modified lemon peel essential oil, thereby loading the modified lemon peel on the silica surface, is beneficial to improving the antibacterial property of vacuum freeze-dried food.

[0016] Preferably, the silica-loaded modified lemon peel essential oil comprises the following raw materials: 3-4 ml modified lemon peel essential oil, 44-47 ml anhydrous ethanol, 0.5-1.5 ml ammonia water, 0.1-0.2 g hexadecyltrimethylammonium bromide, 0.01-0.03 ml β-mercaptoethanol and 1-5 ml ethyl orthosilicate.

[0017] Preferably, the preparation method of the silica-loaded modified lemon peel essential oil is as follows: 3-4 ml of the modified lemon peel essential oil is weighed and mixed with 44-47 ml of anhydrous ethanol, 0.5-1.5 ml of ammonia water, 0.1-0.2 g of hexadecyltrimethylammonium bromide and 0.01-0.03 ml of β-mercaptoethanol, 1-5 ml of ethyl orthosilicate is slowly added dropwise under stirring, and then the mixture is stirred at a constant temperature of 20-30° C. for 3-5 hours. After the loading is completed, the silica loaded with the modified lemon peel essential oil is centrifuged, the supernatant is retained, and the silica precipitate is vacuum freeze-dried to obtain the silica-loaded modified lemon peel essential oil.

[0018] Preferably, the modified lemon peel essential oil comprises the following raw materials: 2.4-3 g lemon peel essential oil, 0.5-1.5 g carboxymethyl chitosan, 55-65 ml anhydrous ethanol and 15-25 ml deionized water, and the hydrophilic group is carboxymethyl.

[0019] Since carboxymethyl chitosan has good water solubility and stability, reacting carboxymethyl chitosan with lemon peel essential oil is beneficial to improving the stability of the lemon peel essential oil, thereby making the lemon peel essential oil less volatile. In addition, carboxymethyl chitosan contains carboxymethyl groups, which makes the carboxymethyl chitosan have good water solubility. By reacting carboxymethyl chitosan with lemon peel essential oil, the hydrophilic group carboxymethyl in the carboxymethyl chitosan can be introduced into the molecular chain of the lemon peel essential oil, thereby improving the water solubility of the lemon peel essential oil.

[0020] Preferably, the preparation method of the modified lemon peel essential oil is as follows: 0.5-1.5 g of carboxymethyl chitosan is weighed and dissolved in 15-25 ml of deionized water, and 55-65 ml of anhydrous ethanol is added after stirring for 25-35 min to form a turbid solution, 2.4-3 g of lemon peel essential oil is weighed and added to the turbid solution, and after stirring evenly, it is placed in a synthesizer at a temperature of 65-75° C. and reacted for 4-4.7 hours to obtain the modified lemon peel essential oil.

[0021] Preferably, the lemon peel essential oil comprises the following raw materials: 350-450g lemon peel, 350-450ml deionized water and 0.8-1.4g anhydrous sodium sulfate.

[0022] Preferably, the preparation method of the lemon peel essential oil is as follows: 350-450g of lemon peel is weighed into a glass culture dish, the surface is covered with plastic wrap and pierced, pre-frozen for 10-14h at -70°C to -90°C, and then dried in a vacuum freeze dryer for 45-51h to obtain a dried lemon peel sample, the lemon slice sample is crushed by a grinder to obtain lemon peel powder, the lemon peel powder is dissolved in 350-450ml of deionized water and placed in a flask, zeolite is added, heated and boiled, and cyclic extraction is performed for 3-5h, the obtained essential oils are mixed, and 0.8-1.4g of anhydrous sodium sulfate is used to remove residual moisture in the essential oils to obtain lemon peel essential oil.

[0023] Preferably, the preparation method of the preservative is as follows: 6-8 g of silica-loaded modified lemon peel essential oil, 2-4 g of sodium phytate and 8-10 ml of deionized water are weighed and stirred at 40-50° C. for 40-50 min.

[0024] The added sodium phytate is a pure natural green additive with strong antioxidant and color protection properties, which can effectively extend the shelf life of food. The added silica-loaded modified lemon peel essential oil can inhibit the growth of bacteria, fungi and viruses, has good antibacterial properties, and is beneficial to prevent food from spoiling, thereby extending the shelf life of food.

[0025] In summary, this application has the following beneficial effects:

[0026] 1. Since the right-handed limonene contained in the modified lemon peel essential oil has a simple structure, it is easily decomposed under the influence of oxidation, light or temperature changes, and the volatile compounds in the modified lemon peel essential oil are easily converted from liquid to gas, resulting in the essential oil being easily volatile. Since the silica-loaded modified lemon peel essential oil adopted in the present application is the modified lemon peel essential oil loaded on the surface of silica, silica has non-toxic and tasteless, is environmentally friendly, absorbs ultraviolet rays, and has stable physical and chemical properties and is used as a carrier for a variety of drugs or active substances. Therefore, silica, as an inert carrier, can protect the active ingredients in the modified lemon peel essential oil from the influence of the external environment, and the modified lemon The volatile components in the lemon peel essential oil reduce the possibility of volatilization and oxidative decomposition, and the microporous structure of silica can be used as an adsorbent for the lemon peel essential oil, helping the modified lemon peel essential oil molecules to adhere to its surface, thereby reducing the amount of essential oil volatilized into the air, which is beneficial to improving the stability of the modified lemon peel essential oil and reducing the volatility of the lemon peel essential oil. Since the interaction between the volatile components in the modified lemon peel essential oil and water molecules is weak, it is difficult to dissolve in water. The introduction of hydrophilic groups to improve the water solubility of the modified lemon peel essential oil, thereby loading the modified lemon peel on the silica surface is beneficial to improving the antibacterial property of vacuum freeze-dried food.

[0027] 2. Since carboxymethyl chitosan has good water solubility and stability, reacting carboxymethyl chitosan with lemon peel essential oil is beneficial to improving the stability of lemon peel essential oil, thereby making the lemon peel essential oil less volatile. Carboxymethyl chitosan contains carboxymethyl groups, which makes carboxymethyl chitosan have good water solubility. By reacting carboxymethyl chitosan with lemon peel essential oil, the hydrophilic group carboxymethyl in carboxymethyl chitosan can be introduced into the molecular chain of lemon peel essential oil, thereby improving the water solubility of lemon peel essential oil.

[0028] 3. The added sodium phytate is a pure natural green additive with strong antioxidant and color protection properties, which can effectively extend the shelf life of food. The added silica-loaded modified lemon peel essential oil can inhibit the growth of bacteria, fungi and viruses, has good antibacterial properties, and is conducive to preventing food from spoiling, thereby extending the shelf life of food. DETAILED DESCRIPTION

[0029] The present application is further described in detail below in conjunction with Examples 1-11 and Comparative Example 1.

[0030] raw material

[0031] Anhydrous ethanol CAS: 64-17-5, ammonia CAS: 1336-21-6, hexadecyltrimethylammonium bromide CAS: 57-09-0, β-mercaptoethanol CAS: 60-24-2, tetraethyl orthosilicate CAS: 78-10-4, carboxymethyl chitosan CAS: 83512-85-0, deionized water CAS: 7732-18-5, lemon peel Sihui Jutianyuan Biotechnology Co., Ltd., anhydrous sodium sulfate CAS: 7757-82-6.

[0032] Example

[0033] Example 1

[0034] A vacuum freeze-drying technology applied to food processing comprises the following raw materials: 7 g of silica-loaded modified lemon peel essential oil, 3 g of sodium phytate and 9 ml of deionized water.

[0035] S1: Arrange, clean and cut food ingredients;

[0036] S2: blanching, precooling and water filtering the food in S1 to obtain the food to be frozen;

[0037] S3: Weigh 400g of lemon peel in a glass culture dish, cover the surface with plastic wrap and pierce it, pre-freeze it at -80°C for 12h, and then dry it in a vacuum freeze dryer for 48h to obtain a dried lemon peel sample, grind the lemon slice sample with a grinder to obtain lemon peel powder, dissolve the lemon peel powder in 400ml of deionized water in a flask, add zeolite, heat and boil, circulate extraction for 4h, mix the obtained essential oils, and remove the residual moisture of the essential oils with 1.1g of anhydrous sodium sulfate to obtain lemon peel essential oil;

[0038] S4: Weigh 1 g of carboxymethyl chitosan and dissolve it in 20 ml of deionized water. After stirring for 30 min, add 60 ml of anhydrous ethanol to form a turbid solution. Weigh 2.7 g of lemon peel essential oil and add it to the turbid solution. After stirring evenly, put it into a synthesizer at a temperature of 70°C and react for 4.35 h to obtain modified lemon peel essential oil.

[0039] S5: Weigh 3.5 ml of modified lemon peel essential oil, 45.5 ml of anhydrous ethanol, 1 ml of ammonia water, 0.15 g of hexadecyltrimethylammonium bromide and 0.02 ml of β-mercaptoethanol, slowly drop 3 ml of ethyl orthosilicate under stirring, and then react at 25 ° C. for 4 hours. After the loading is completed, the silica loaded with modified lemon peel essential oil is centrifuged, the supernatant is retained, and the silica precipitate is vacuum freeze-dried to obtain silica loaded with modified lemon peel essential oil;

[0040] S6: Prepare a preservative, weigh 7 g of silica-loaded modified lemon peel essential oil, 3 g of sodium phytate and 9 ml of deionized water and stir at 45 °C for 45 min;

[0041] S7: soaking the food to be frozen in a preservative, and performing vacuum freeze drying on the food;

[0042] S8: Pack the vacuum freeze-dried food and store it in a cold warehouse.

[0043] Example 2-3

[0044] The difference from Example 1 is that the added amounts of the various components of the preservative are different, as shown in Table 1.

[0045] Table 1 Addition amount of each component of the preservative in Examples 1-3

[0046] Example 1 Example 2 Example 3 Silica-loaded modified lemon peel essential oil 7g 8g 6g Sodium Phytate 3g 2g 4g Deionized water 9ml 10ml 8ml

[0047] Example 4

[0048] The difference from Example 1 is that the silica-loaded modified lemon peel essential oil is replaced by an equal amount of lemon peel essential oil.

[0049] Example 5

[0050] The difference from Example 1 is that the silica-loaded modified lemon peel essential oil is replaced by an equal amount of modified lemon peel essential oil.

[0051] Embodiment 6-7

[0052] The difference from Example 1 is that the addition amount of each component of the silica-loaded modified lemon peel essential oil is different, as shown in Table 2.

[0053] Table 2 Addition amount of each component of silica-loaded modified lemon peel essential oil in Example 1 and Examples 6-7

[0054] Example 1 Example 6 Example 7 Modified lemon peel essential oil 3.5ml 3 4 Anhydrous ethanol 45.5ml 44 47 ammonia 1ml 1.5 0.5 Hexadecyltrimethylammonium bromide 0.15g 0.1 0.2 β-Mercaptoethanol 0.02ml 0.3 0.1 Tetraethyl orthosilicate 3ml 5 1

[0055] Embodiment 8-9

[0056] The difference from Example 1 is that the added amounts of the components of the modified lemon peel essential oil are different, as shown in Table 3.

[0057] Table 3 Addition amount of each component of modified lemon peel essential oil in Example 1 and Examples 8-9

[0058] Example 1 Example 8 Example 9 Lemon peel essential oil 2.7g 3g 2.4g Carboxymethyl chitosan 1g 0.5g 1.5g Anhydrous ethanol 60ml 65ml 55ml Deionized water 20ml 15ml 25ml

[0059] Embodiment 10-11

[0060] The difference from Example 1 is that the addition amount of each component of the lemon peel essential oil is different, as shown in Table 4.

[0061] Table 4 Addition amount of each component of lemon peel essential oil in Example 1 and Examples 10-11

[0062] Example 1 Example 10 Embodiment 11 Lemon zest 400g 350g 450g Deionized water 400ml 450ml 350ml Anhydrous sodium sulfate 1.1g 0.8g 1.4g

[0063] Comparative Example

[0064] Comparative Example 1

[0065] The difference from Example 1 is that no preservative is added for soaking the food.

[0066] Performance testing

[0067] Detection Methods

[0068] 1. Antibacterial properties

[0069] Three samples were taken from Examples 1-11 and Comparative Example 1, respectively, and the results were compared with those in GB / T4789.2-2010.

[0070] The antibacterial performance test of "Determination of Total Colony Count in Food Hygiene Microbiology Testing" is carried out, and then the total colony count is obtained and the average value is taken.

[0071] The test data are shown in Table 5.

[0072] Table 5 Antibacterial performance test table of Examples 1-11 and Comparative Example 1

[0073]

[0074]

[0075] Combining Example 1 and Comparative Example 1 and Table 5, it can be seen that the total colony count of Comparative Example 1 is significantly increased compared with that of Example 1, which indicates that, compared with directly vacuum freeze-drying the food, soaking the food in a preservative and then vacuum freeze-drying the food can effectively improve the antibacterial properties of the food.

[0076] The reason is that the modified lemon peel essential oil is loaded on the surface of silica. Silica has non-toxic and tasteless, environmentally friendly, ultraviolet absorption, stable physical and chemical properties and is used as a carrier of various drugs or active substances. Therefore, silica, as an inert carrier, can protect the active ingredients in the modified lemon peel essential oil from the influence of the external environment. The volatile components in the modified lemon peel essential oil reduce the possibility of volatilization and oxidative decomposition, and the microporous structure of silica can be used as an adsorbent for the lemon peel essential oil, helping the modified lemon peel essential oil molecules to adhere to its surface, thereby reducing the amount of essential oil volatilized into the air, which is beneficial to improving the stability of the modified lemon peel essential oil and reducing the volatility of the lemon peel essential oil. Since the interaction between the volatile components in the modified lemon peel essential oil and water molecules is weak, it is difficult to dissolve in water. The introduction of hydrophilic groups to improve the water solubility of the modified lemon peel essential oil, thereby loading the modified lemon peel on the silica surface is beneficial to improving the antibacterial properties of vacuum freeze-dried food.

[0077] Combining Example 1 with Examples 2-3 and Table 5, it can be seen that the total number of colonies in Examples 2 and 3 increased compared with that in Example 1, which indicates that the amount of each component of the preservative added affects the antibacterial properties of food.

[0078] Combining Example 1 and Example 4 and Table 5, it can be seen that the total colony count in Example 4 is increased compared with that in Example 1, which shows that, compared with adding lemon peel essential oil, adding silica-loaded modified lemon peel essential oil can effectively improve the antibacterial properties of food.

[0079] Combining Example 1 and Example 5 and Table 5, it can be seen that the total colony count in Example 5 is increased compared with that in Example 1, which indicates that, compared with adding modified lemon peel essential oil, adding silica-loaded modified lemon peel essential oil can effectively improve the antibacterial properties of food.

[0080] Combining Example 1 and Examples 6-7 and Table 5, it can be seen that relative to Example 1, the total number of colonies in Examples 6 and 7 increased, which shows that the addition amount of each component of the silica-loaded modified lemon peel essential oil affects the antibacterial properties of the food.

[0081] Combining Example 1 and Examples 8-9 with Table 5, it can be seen that relative to Example 1, the total number of colonies in Examples 8 and 9 increased, which shows that the addition amount of each component of the modified lemon peel essential oil affects the antibacterial properties of food.

[0082] Combining Example 1 and Examples 10-11 and Table 5, it can be seen that relative to Example 1, the total number of colonies in Examples 10 and 11 increased, which shows that the addition amount of each component of lemon peel essential oil affects the antibacterial property of food.

[0083] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A vacuum freeze-drying technology used in food processing, characterized in that: The following steps are involved: S1: Arrange, clean and cut food ingredients; S2: blanching, precooling and water filtering the food in S1 to obtain the food to be frozen; S3: prepare preservative; S4: placing the food to be frozen in S2 into the preservative in S3 for soaking, and performing vacuum freeze drying on the food; S5: Packing the vacuum freeze-dried food and storing it in a cold warehouse; The preservative in S2 comprises the following raw materials: 6-8 g of silica-loaded modified lemon peel essential oil, 2-4 g of sodium phytate and 8-10 ml of deionized water; The silica-loaded modified lemon peel essential oil is a modified lemon peel essential oil loaded on the surface of silica, and a hydrophilic group is introduced into the modified lemon peel essential oil.

2. The vacuum freeze-drying technology for food processing according to claim 1, characterized in that: The silica-loaded modified lemon peel essential oil comprises the following raw materials: 3-4 ml of modified lemon peel essential oil, 44-47 ml of anhydrous ethanol, 0.5-1.5 ml of ammonia water, 0.1-0.2 g of hexadecyltrimethylammonium bromide, 0.01-0.03 ml of beta-mercaptoethanol and 1-5 ml of ethyl orthosilicate.

3. A vacuum freeze-drying technology for food processing according to claim 2, characterized in that: The preparation method of the silica-loaded modified lemon peel essential oil comprises the following steps: weighing 3-4 ml of the modified lemon peel essential oil, 44-47 ml of anhydrous ethanol, 0.5-1.5 ml of ammonia water, 0.1-0.2 g of hexadecyltrimethylammonium bromide and 0.01-0.03 ml of beta-mercaptoethanol, slowly dropping 1-5 ml of ethyl orthosilicate under stirring, and then stirring the mixture at a constant temperature of 20-30° C. for 3-5 hours. After the loading is completed, centrifuging the silica loaded with the modified lemon peel essential oil, retaining the supernatant, and taking the silica precipitate for vacuum freeze drying to obtain the silica-loaded modified lemon peel essential oil.

4. The vacuum freeze-drying technology for food processing according to claim 3, characterized in that: The modified lemon peel essential oil comprises the following raw materials: 2.4-3g of lemon peel essential oil, 0.5-1.5g of carboxymethyl chitosan, 55-65ml of anhydrous ethanol and 15-25ml of deionized water, and the hydrophilic group is carboxymethyl.

5. The vacuum freeze-drying technology for food processing according to claim 4, characterized in that: The preparation method of the modified lemon peel essential oil comprises the following steps: weighing 0.5-1.5 g of carboxymethyl chitosan and dissolving it in 15-25 ml of deionized water, stirring for 25-35 min, adding 55-65 ml of anhydrous ethanol to form a turbid solution, weighing 2.4-3 g of lemon peel essential oil and adding it to the turbid solution, stirring evenly, and then placing the solution in a synthesizer at a temperature of 65-75° C. to react for 4-4.7 hours to obtain the modified lemon peel essential oil.

6. The vacuum freeze-drying technology for food processing according to claim 5, characterized in that: The lemon peel essential oil comprises the following raw materials: 350-450 g of lemon peel, 350-450 ml of deionized water and 0.8-1.4 g of anhydrous sodium sulfate.

7. The vacuum freeze-drying technology for food processing according to claim 6, characterized in that: The preparation method of the lemon peel essential oil comprises the following steps: weighing 350-450 g of lemon peel into a glass culture dish, covering the surface with plastic wrap and punching holes, pre-freezing the lemon peel for 10-14 h at -70°C to -90°C, and drying the lemon peel in a vacuum freeze dryer for 45-51 h to obtain a dried lemon peel sample, crushing the lemon slice sample with a crusher to obtain lemon peel powder, dissolving the lemon peel powder in 350-450 ml of deionized water and placing the mixture in a flask, adding zeolite, heating and boiling, and cyclically extracting for 3-5 h, mixing the obtained essential oils, and removing residual moisture in the essential oils with 0.8-1.4 g of anhydrous sodium sulfate to obtain the lemon peel essential oil.

8. The vacuum freeze-drying technology for food processing according to claim 7, characterized in that: The preparation method of the preservative is as follows: 6-8g of silica-loaded modified lemon peel essential oil, 2-4g of sodium phytate and 8-10ml of deionized water are weighed and stirred at 40-50°C for 40-50min.

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