Method for preparing strong-fragrance camellia oil based on medium-temperature squeezing synergetic condensation fragrance recovery technology

Abstract

The invention relates to the technical field of edible oil and fat processing, in particular to a method for preparing strong-fragrance camellia oil based on a medium-temperature squeezing and condensation fragrance recovery technology, and the method comprises the following steps: pretreatment, squeezing, fragrance component trapping, fragrance component readdition and nitrogen-filled packaging. By adopting the method disclosed by the invention, resource utilization of fragrance is realized, the contradiction between insufficient generation of fragrance substances and volatilization loss in the squeezing process and excessive benzopyrene and active ingredient damage caused by a high-temperature process are solved, and the method has outstanding substantive significance.

Description

Technical Field

[0001] The present invention relates to the technical field of edible oil processing, and particularly to a method for preparing strongly fragrant camellia oil based on medium-temperature pressing and condensation fragrance recovery technology. Background Art

[0002] The unsaturated fatty acid content of camellia oil is as high as over 90% (oleic acid 80 - 83%, linoleic acid 7 - 13%), rich in vitamins A, B, D, E and linolenic acid, and free of erucic acid, cholesterol and aflatoxin. Its nutritional value is listed as the top recommended health edible oil by the Food and Agriculture Organization of the International. However, the traditional production process of camellia oil has the following problems:

[0003] 1. Although the low-temperature pressing method (such as cold pressing process) can retain active ingredients, the release of flavor substances is insufficient and the flavor is weak.

[0004] 2. The high-temperature pressing method (>150°C) is likely to cause the excessive standard of harmful substances such as benzo[a]pyrene, and the high temperature destroys the flavor precursor substances.

[0005] 3. Existing flavor enhancement technologies do not solve the problem of volatilization loss of flavor components and have complex processes.

[0006] 4. Lack of flavor recovery technology: Most of the volatile esters, aldehydes and other flavor substances generated during the pressing process escape with the waste gas, and the existing technology has not achieved directional collection and reuse.

[0007] After retrieval, existing patents (such as CN102524428B, CN103484243A) mainly focus on the removal of benzo[a]pyrene or the improvement of single pressing process, and do not involve the combination of flavor substance condensation recovery technology. CN115261113A retains active ingredients but sacrifices flavor intensity.

[0008] The annual growth rate of consumers' demand for strongly fragrant camellia oil is 15%, but there is a cognitive contradiction of "high fragrance means high risk" in the commercially available products. It is still necessary to break through the technical bottlenecks of "preserving fragrance" and "removing hazards". Therefore, it is necessary to propose a method for preparing strongly fragrant camellia oil based on medium-temperature pressing and condensation fragrance recovery technology. Summary of the Invention

[0009] In view of the above, it is necessary to provide a method for preparing strongly fragrant camellia oil based on medium-temperature pressing and condensation fragrance recovery technology. The present invention first proposes the medium-temperature pressing and condensation fragrance recovery technology, breaking through the contradiction between fragrance retention and safety.

[0010] To achieve the above object, the technical solution adopted by the present invention is:

[0011] A method for preparing strongly fragrant camellia oil based on medium-temperature pressing and condensation fragrance recovery technology, the method comprising the following steps:

[0012] (1) Pretreatment: Roast the camellia seeds and set aside for later use.

[0013] (2) Pressing: Take the roasted camellia seeds and press them under the conditions of 100 - 120°C and 18 - 25 MPa to obtain crude oil, and simultaneously collect the pressing exhaust gas.

[0014] (3) Aroma component capture: After passing the pressing exhaust gas from step (2) through a pre - stage oil - gas separation membrane, it enters a 4°C pre - cooling dehydration dryer, and then enters a three - stage gradient condensation system for treatment to obtain a concentrated aroma liquid and set aside.

[0015] (4) Aroma component addition back: Add 0.007 - 0.009 wt% citric acid and 0.001 - 0.003 wt% disodium EDTA chelating treatment to the crude oil, then mix in 0.05 - 0.15 wt% concentrated aroma liquid, and then through post - treatment, the concentrated fragrant camellia oil can be obtained.

[0016] (5) Nitrogen filling and packaging.

[0017] Further, before the camellia seeds in step (1) are roasted, first dry the camellia seeds in the sun until the moisture content is less than 12%, then shell, remove impurities, and ripen through a steaming tower and set aside.

[0018] Further, the roasting treatment in step (1) adopts hot - air gradient roasting, specifically: first roast at 80°C for 2 - 4 minutes, then roast at 100°C for 2 - 4 minutes, and finally roast at 120°C for 2 - 4 minutes.

[0019] Further, the pre - cooling dehydration and three - stage gradient condensation system in step (3) includes in sequence: Pre - cooling and drying: Use 2 - 4°C stainless - steel finned coil pipes to dehydrate the inhaled pressing exhaust gas, prevent humid air from entering the subsequent condensation recovery system. The condensed water removed contains certain fragrant substances, and the condensed water is removed through a water - oil separation tank, and the oily fragrant substances are then recovered through a small - scale distillation and condensation recovery system. The condensation recovery system includes: First stage: - 4 to - 6°C stainless - steel coil condensation, Second stage: - 14 to - 16°C enhanced condensation, Third stage: - 23 to - 25°C deep - cold coil.

[0020] Further, the chelating treatment in step (4) includes: First pre - heat the crude oil to 38 - 42°C, add citric acid and stir for 10 - 12 min, then add disodium EDTA and stir for 15 - 20 min.

[0021] Further, the post - treatment in step (4) is: Shear and emulsify at 5000 - 6000 rpm for 10 - 15 min, and then deoxidize through a 0.14 - 0.16μm membrane.

[0022] Further, the three - stage gradient condensation adopts a stainless - steel coil condenser.

[0023] Further, the purity of nitrogen gas for nitrogen filling packaging in step (5) is ≥99.99%.

[0024] The present invention has the following beneficial effects: This step-by-step process increases the metal ion chelation rate from 85% to 98% (P < 0.01), and avoids the flocculation problem caused by the competitive binding of EDTA and citric acid.

[0025] The present invention provides a method for preparing strongly fragrant camellia oil based on medium-temperature pressing and co-condensation fragrance recovery technology, realizing the resource utilization of fragrance. This method simultaneously solves the contradiction between insufficient generation and volatilization loss of fragrance substances during the pressing process and the problems of excessive benzo[a]pyrene and damage of active ingredients caused by high-temperature processes, and has outstanding practical significance.

[0026] First, the present application conducts directional enrichment of fragrance substances. By activating lipoxygenase through medium-temperature pressing and promoting the Maillard reaction through gradient roasting, the contents of key aroma substances (trans-2-nonenal, hexanal) are increased. Then, a three-stage condensation system (-5°C → -15°C → -24°C) is used to capture the escaped fragrance components, and the fragrance components are recycled. When adding fragrance substances, the recycled fragrance concentrate is evenly dispersed into the camellia oil matrix through high-shear emulsification, solving the problem of oxidative instability caused by uneven distribution of fragrance components. Finally, after membrane deoxidation treatment, through the synergistic action of physical retention and gas replacement, deep removal of dissolved oxygen in the oil product is achieved, providing ultimate guarantee for flavor stability.

[0027] Secondly, the present application has a two-dimensional guarantee of safety. One is to reduce the content of harmful substance benzo[a]pyrene by precisely controlling the temperature, and to improve the chelation rate by compounding a chelation system (citric acid + disodium EDTA), removing transition metal ions (Fe 3+ residual ≤ 0.05 ppm), and the obtained finished product has a pure flavor without interference. Moreover, the present application also adopts a process of step-by-step addition, further increasing the chelation rate and avoiding the flocculation problem caused by the competitive binding of EDTA and citric acid, maintaining fragrance stability.

[0028] In addition, the present application also optimizes the process efficiency and cost. By using the condensation and backfilling technology of the present application, the raw material utilization rate is increased, the addition cost of essence is reduced, and medium-temperature pressing is more energy-saving than high-temperature processes, and the membrane deoxidation system consumes less energy than vacuum deoxidation. In summary, the method of the present application can not only improve the quality of the obtained product, but also reduce the production cost. Specific embodiments

[0029] All the features disclosed in this specification, or all the steps in any method or process disclosed, can be combined in any way, except for mutually exclusive features and / or steps.

[0030] Any feature disclosed in this specification (including any appended claims, abstract) is, unless otherwise specified, only an example of a series of equivalent or similar features.

[0031] Example 1:

[0032] This example provides a method for preparing strongly fragrant camellia oil based on medium-temperature pressing combined with condensation and flavor recovery technology. The method comprises the following steps:

[0033] Step 1: Pretreatment

[0034] Dry the camellia seeds in the sun until the moisture content is lower than 12%, then shell, remove impurities, and after ripening through a steaming tower, perform hot-air gradient roasting, specifically: first roast at 80°C for 2 minutes, then roast at 100°C for 2 minutes, and finally roast at 120°C for 2 minutes;

[0035] Step 2: Medium-temperature pressing

[0036] Take the roasted camellia seeds and press them under the conditions of 100°C and 18 MPa to obtain crude oil, and simultaneously collect the pressing waste gas;

[0037] Step 3: Capture of flavor components

[0038] After passing the pressing waste gas through a pre-stage oil-gas separation membrane, first enter a 2°C pre-cooling dehydration dryer, and then enter a three-stage gradient condensation system for treatment. The three-stage gradient condensation system successively includes: Stage 1: -4°C stainless steel coil condensation, Stage 2: -14°C enhanced condensation, Stage 3: -23°C deep-cooling coil to obtain a flavor concentrate for standby; The three-stage gradient condensation uses a stainless steel coil condenser;

[0039] Step 4: Addition of flavor components

[0040] Add 0.007 wt% citric acid and 0.001 wt% disodium EDTA for chelating treatment to the crude oil. First preheat the crude oil to 38°C, add citric acid and stir for 10 min, then add disodium EDTA and stir for 15 min, then mix in 0.05 wt% flavor concentrate, shear and emulsify at 5000 rpm for 10 min, and then perform 0.14 μm membrane deoxidation to obtain the strongly fragrant camellia oil;

[0041] Step 5: Nitrogen filling and packaging

[0042] The nitrogen is 99.995% nitrogen (the headspace oxygen content ≤ 0.5%).

[0043] Example 2:

[0044] This example provides a method for preparing strongly fragrant camellia oil based on medium-temperature pressing combined with condensation and flavor recovery technology. The method comprises the following steps:

[0045] Step 1: Pretreatment

[0046] The camellia seeds are sun-dried until the moisture content is lower than 12%, then shelled, decontaminated, and cooked in a steaming tower, followed by hot air gradient roasting. Specifically: first, roast at 80°C for 3 minutes, then roast at 100°C for 3 minutes, and finally roast at 120°C for 3 minutes;

[0047] Step 2: Medium-temperature pressing

[0048] Take the roasted camellia seeds and press them under the conditions of 110°C and 22 MPa to obtain crude oil, and simultaneously collect the pressing waste gas;

[0049] Step 3: Aroma component capture

[0050] After passing the pressing waste gas through a pre-stage oil-gas separation membrane, it first enters a pre-cooling dehydration dryer at 3°C, and then enters a three-stage gradient condensation system for treatment. The three-stage gradient condensation system successively includes: the first stage: -5°C stainless steel coil condensation, the second stage: -15°C enhanced condensation, and the third stage: -24°C deep-cooling coil to obtain an aroma concentrate for standby; the three-stage gradient condensation uses a stainless steel coil condenser;

[0051] Step 4: Aroma component backfilling

[0052] Add 0.008 wt% citric acid and 0.002 wt% disodium EDTA for chelating treatment to the crude oil. First, preheat the crude oil to 40°C, add citric acid and stir for 10 min, then add disodium EDTA and stir for 18 min, then mix in 0.1 wt% aroma concentrate, shear and emulsify at 5500 rpm for 12 min, and then deoxygenate through a 0.15 μm membrane to obtain the concentrated fragrant camellia oil;

[0053] Step 5: Nitrogen filling and packaging

[0054] The nitrogen is 99.995% nitrogen (the oxygen content in the headspace ≤ 0.5%).

[0055] Example 3:

[0056] This example provides a method for preparing concentrated fragrant camellia oil based on medium-temperature pressing and condensation and flavor return technology. The method includes the following steps:

[0057] Step 1: Pretreatment

[0058] The camellia seeds are sun-dried until the moisture content is lower than 12%, then shelled, decontaminated, and cooked in a steaming tower, followed by hot air gradient roasting. Specifically: first, roast at 80°C for 4 minutes, then roast at 100°C for 4 minutes, and finally roast at 120°C for 4 minutes;

[0059] Step 2: Medium-temperature pressing

[0060] Take the roasted camellia seeds, press them under the conditions of 120 °C and 25 MPa to obtain crude oil, and simultaneously collect the pressing waste gas;

[0061] Step 3: Aroma component capture

[0062] After passing the pressing waste gas through a pre - placed oil - gas separation membrane, it first enters a pre - cooling dehydration dryer at 4 °C, and then enters a three - stage gradient condensation system for treatment. The three - stage gradient condensation system successively includes: the first stage: - 6 °C stainless steel coil condensation, the second stage: - 16 °C enhanced condensation, and the third stage: - 25 °C deep - cold coil to obtain a concentrated aroma liquid for standby; the three - stage gradient condensation uses a stainless steel coil condenser;

[0063] Step 4: Aroma component back - addition

[0064] Add 0.009 wt% citric acid and 0.003 wt% disodium EDTA for chelating treatment to the crude oil. First, pre - heat the crude oil to 42 °C, add citric acid and stir for 12 min, then add disodium EDTA and stir for 20 min. Then mix in 0.15 wt% of the concentrated aroma liquid, shear and emulsify at 6000 rpm for 15 min, and then deoxygenate through a 0.16 μm membrane to obtain the concentrated - aroma camellia oil;

[0065] Step 5: Nitrogen - filling packaging

[0066] The nitrogen is 99.995% nitrogen (the oxygen content in the headspace ≤ 0.5%).

[0067] Test data:

[0068] Test 1: Compare the effects under different pre - treatments

[0069] It is divided into the following groups:

[0070] The present invention: the method of Example 2 of this application, that is, through three - stage temperature control of 80 °C → 100 °C → 120 °C (each for 3 min);

[0071] Traditional process: the conventional method, that is, using a single high - temperature mode of 140 °C for 25 minutes, lacking a gradient temperature - rising design.

[0072] In addition, the other treatment methods of the two are the same. Compare the effects after the above - mentioned group treatments, and the results are shown in Table 1:

[0073] Table 1

[0074]

[0075] According to the results in Table 1, the process of the present invention has better effects. Through a three-stage temperature control mode, it activates lipoxygenase (enzyme activity ≥ 480 U / g), promotes the conversion of linoleic acid into flavor precursors such as hexanal, effectively initiates the Maillard reaction (ΔE = 25), and generates pyrazine-like nutty flavors. In contrast, the traditional process causes flavor loss, nutrient loss, and safety risks (benzo[a]pyrene exceeding the standard).

[0076] Experiment 2: Comparing the effects of pressing temperatures

[0077] The applicant also compared the safety risks and the production amounts of main flavor substances at different pressing temperatures, and the grouping is as follows:

[0078] The present invention: The method of Example 2 of this application, that is, medium-temperature pressing is carried out at 110 °C;

[0079] High-temperature pressing group: The pressing temperature is 150 °C;

[0080] In addition, the other treatment methods of the two groups are the same. The benzo[a]pyrene content and the production amount of trans-2-nonenal of the two groups were compared, and the results are shown in Table 2:

[0081] Table 2

[0082] Index High-temperature pressing (150°C) This invention Benzo[a]pyrene content 10 μg / kg 0.3 μg / kg Trans-2-nonenal production 45 mg / kg 152 mg / kg

[0083] According to the results in Table 2, the present invention conducts precise temperature control, effectively increasing the content of flavor substances and reducing the content of harmful substances. In addition, it can be seen from the data in the table that there is a huge gap when the temperature difference is 40 °C, indicating that the control of temperature is very crucial and unpredictable.

[0084] Experiment 3: Comparing the condensation recovery effects

[0085] The applicant further tested the recovery rate of total flavor components, the capture rate of main flavor components, and the purity of condensate under different processes of condensing and recovering flavor substances. The grouping is as follows:

[0086] Three-stage condensation of the present invention: Adopting the method of Example 2 of this application, three-stage condensation (-5 °C → -15 °C → -24 °C) is carried out;

[0087] Two-stage condensation: Only two-stage condensation (-5 °C → -15 °C) is carried out;

[0088] In addition, the other treatment methods of the two groups are the same. The condensation effects of the above groups were compared, and the results are shown in Table 3:

[0089] Table 3

[0090]

[0091]

[0092] According to the results in Table 3, it can be seen that the three-stage condensation of this application effectively improves the capture rate of flavor substances.

[0093] Experiment 4: Comparing the effects of different chelation treatments

[0094] The applicant further tested the indicators such as the residual amount of transition metals under different chelation treatments, and the grouping is as follows:

[0095] Double chelation of the present invention: adopting the chelation method of Example 2 of this application;

[0096] Non-stepwise double chelation: adopting the chelating agent of Example 2 of this application, but not adding it step by step, and directly adding it together;

[0097] Single citric acid: only using 0.01% citric acid as the chelating agent;

[0098] Single EDTA: only using 0.002% EDTA as the chelating agent;

[0099] No chelation: no chelation treatment is carried out.

[0100] In addition, the other treatment methods of the two groups are the same. Comparing the chelation effects of the above groups, the results are shown in Table 4:

[0101] Table 4

[0102]

[0103] According to the results in Table 4, it can be seen that by adopting the stepwise double chelation treatment of this application, the chelation rate and the retention rate of nonanal can be improved, the metal residue can be effectively reduced, and the safety of the refined oil can be improved. In addition, the applicant found that precipitation and flocculation also occurred in the non-stepwise double chelation treatment group, and 120 mg / kg of precipitate appeared.

[0104] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it cannot be understood as a limitation to the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A method for preparing strongly fragrant camellia oil based on medium-temperature pressing and co-condensation flavor return technology, characterized in that, The method includes the following steps: (1) Pretreatment: The camellia seeds are roasted and then reserved for use; (2) Pressing: Take the roasted camellia seeds and press them under the conditions of 100 - 120 °C and 18 - 25 MPa to obtain crude oil, and simultaneously collect the pressing exhaust gas; (3) Aroma component capture: After passing the pressing exhaust gas in step (2) through a pre - placed oil - gas separation membrane, it enters a three - stage gradient condensation system for treatment to obtain a concentrated aroma liquid, and reserve it for use; (4) Aroma component addition back: Add 0.007 - 0.009 wt% citric acid and 0.001 - 0.003 wt% disodium EDTA for chelating treatment to the crude oil, then mix in 0.05 - 0.15 wt% of the concentrated aroma liquid, and then through post - treatment, the concentrated fragrant camellia oil can be obtained; (5) Nitrogen - filling packaging.

2. The method according to claim 1, wherein Before the camellia seeds in step (1) are roasted, first dry the camellia seeds until the moisture content is lower than 12%, then shell, remove impurities, and after ripening through a steaming tower, reserve them for use.

3. The method according to claim 1, characterized in that, The roasting treatment in step (1) adopts hot - air gradient roasting, specifically: first roast at 80 °C for 2 - 4 minutes, then roast at 100 °C for 2 - 4 minutes, and finally roast at 120 °C for 2 - 4 minutes.

4. The method according to claim 1, characterized in that The three - stage gradient condensation system in step (3) successively includes: the first stage: - 4~ - 6 °C stainless - steel coil condensation, the second stage: - 14~ - 16 °C enhanced condensation, and the third stage: - 23~ - 25 °C cryogenic coil.

5. The method according to claim 1, characterized in that, The chelating treatment in step (4) includes: first pre - heat the crude oil to 38 - 42 °C, add citric acid and stir for 10 - 12 min, and then add disodium EDTA and stir for 15 - 20 min.

6. The method according to claim 1, characterized in that The post - treatment in step (4) is: shear and emulsify at 5000 - 6000 rpm for 10 - 15 min, and then deoxidize through a 0.14 - 0.16 μm membrane.

7. The method according to claim 3, characterized in that, The three - stage gradient condensation adopts a stainless - steel coil condenser.

8. The method according to claim 1, characterized in that The nitrogen purity of the nitrogen - filling packaging in step (5) is ≥99.99%.

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