CN114874837A - A kind of method for preparing walnut oil by water enzymatic method - Google Patents

Abstract

The invention relates to the technical field of food, in particular to a method for preparing walnut oil by an aqueous enzymatic method, which comprises the steps of crushing pretreated walnut kernels under the condition of not adding water, wherein the particle size of the crushed walnut kernels is less than or equal to 900 micrometers; adding water into the crushed walnut kernels to prepare walnut pulp; carrying out enzymolysis on the walnut pulp by using an aqueous enzymatic method; the method provided by the invention greatly improves the enzymolysis efficiency, and the final oil yield is up to more than 70%.

Description

A kind of method for preparing walnut oil by water enzymatic method

technical field

The invention relates to the technical field of food, in particular to a method for preparing walnut oil by an aqueous enzymatic method.

Background technique

At present, the common methods in the current production of walnut oil mainly include:

(1) Pressing method: It is the most commonly used method in the current production of walnut oil, and it is also a relatively mature walnut oil extraction method. He mainly uses the principle of mechanical pressing to squeeze out the oil in the raw materials at one time. Typically, the machinery used includes screw presses and hydraulic presses. The denaturation temperature of walnut protein is 67.5 ℃. According to the degree of denaturation of walnut protein, mechanical pressing can be divided into cold pressing and hot pressing. Generally speaking, the hot pressing method uses a screw press; the cold pressing method uses a hydraulic press. Cold pressing, using physical pressing method to press oil at 60℃, completely retain the nutrients in the oil. Reduce the crushing, steaming, frying and other links in the hot pressing process. The pressed edible oil can meet the national three-level edible oil standard. Hot pressing uses the physical pressing method to press the material at high temperature at 120-130 °C, and the oil yield is high. The oil needs to be crushed, softened, rolled, steamed and fried. The pressed crude oil needs to be refined, and the equipment is more complicated. . The disadvantage is that the hot pressing method requires high temperature baking and high energy consumption, and the hot pressing uses a screw oil press, although the work efficiency is high, but in order to increase the frictional resistance during pressing, it is necessary to introduce walnut shells, which is not conducive to the reuse of walnut meal; cold; Although the pressing method does not have the above shortcomings, the oil yield is low.

(2) Oil production by leaching method: It is a kind of system that applies the principle of extraction, selects a certain organic solvent that can dissolve oil, and makes it contact with the pretreated oil—soaking or spraying, so that the oil in the oil is dissolved. oil method. This method makes the solution of the solvent and the oil it dissolves called mixed oil. Using the different boiling points of the selected solvent and the oil, the mixed oil is evaporated and stripped, the solvent is evaporated, and the oil is left to obtain the crude oil. The rectified solvent vapor is recovered by condensation and recycled. Leaching usually soaks the raw material with solvent oil (No. 6 light gasoline), and sucks out the oil in the raw material. Then, the mixed oil is heated to 240-260℃, and the light gasoline is evaporated first, leaving the crude oil, and then the six processes of degreasing, degumming, dehydration, decolorization, deodorization and deacidification are carried out to refine into edible oil. The state stipulates that the residues in the first and second grade edible oils shall not exceed 10 mg/kg; the residues in the third and fourth grade edible oils shall not exceed 50 mg/kg.

(3) Supercritical CO ₂ extraction method: it has high extraction efficiency, no residual solvent toxicity, natural active ingredients and heat-sensitive ingredients are not easy to be decomposed and destroyed, can maximize the natural characteristics of the extract, and can achieve selective separation, etc. advantage. In the extraction of edible oil, the extraction of vegetable oil has always had a lot of room for improvement, because the general extraction method may lead to the dissipation and oxidation of the active ingredients in the plant. However, the equipment has a large one-time investment and high energy consumption.

(4) Water substitution method: It is a method of replacing oil with water from oil plants to obtain fat. No pressure is needed to squeeze out, no solvent is used, and depending on certain conditions, the affinity of water and protein is greater than that of oil and protein, so water enters the oil and replaces the oil. It is used to prepare sesame oil, and it can also be used for oil plants with high oil content such as peanuts, tea seeds and sunflower seeds.

The prior art discloses a method for efficient processing of walnut oil, which adopts processes such as pretreatment-enzymolysis-fermentation-secondary cooking-pressing. This application requires both enzymatic hydrolysis and fermentation, and also requires secondary cooking, and finally pressing to obtain walnut oil. The process is complicated, the operating cost is high, and the production cycle is long, and the method is still essentially The walnut oil is obtained by pressing method.

The prior art discloses a method for preparing pecan oil by a water enzymatic method. The walnut has a moisture content of 5.0% to 5.5% and is not peeled. After crushing, water is added to the volume to make a secondary enzymatic hydrolysis, and pH is adjusted to obtain the highest oil yield. was 71.2%. The application has certain requirements on the moisture content of the walnut kernel, and the fact that the walnut is not peeled will have a certain impact on the taste and color of the walnut oil.

The prior art discloses a method for extracting pecan oil with water enzyme, which adopts a hydrocolloid mill, adjusts pH after constant volume, goes through cellulase once, papain twice, enzymolysis twice, and centrifugation to obtain walnut oil. The enzymolysis time is 3-8h. The application needs to undergo two centrifugal enzymatic hydrolysis, and the enzymatic hydrolysis time is as high as 8h.

SUMMARY OF THE INVENTION

Therefore, the technical problem to be solved by the present invention is to overcome the defects of numerous steps and low oil yield in the prior art, thereby providing a method for preparing walnut oil by an aqueous enzymatic method.

Studies have shown that part of walnut oil exists between walnut cells, and another part of walnut oil exists in walnut cells. In order to release the walnut oil, it needs to be broken. On the one hand, the walnut oil can be initially released; on the other hand, the particle size of the walnut is reduced, the specific surface area is increased, and the contact between the enzyme and the walnut is increased. The invention adopts the water enzymatic method, after the enzyme and the walnut slurry are evenly mixed, enzymolysis is carried out at a certain temperature, and the walnut oil is obtained by centrifugation.

The invention adopts peeled walnut kernels, and the moisture content can be achieved between 1% and 30%. By crushing the walnut kernels to a suitable particle size without adding water, the emulsification effect can be weakened and the oil yield can be improved.

A method for preparing walnut oil by water enzymatic method, specifically comprises the steps:

In the case of not adding water, crush the pretreated walnut kernels, and the particle size of the crushed walnut kernels is less than or equal to 900 μm; add water to the crushed walnut kernels to prepare walnut pulp; The pulp is enzymatically hydrolyzed; the enzymatic hydrolyzed walnut pulp is separated to obtain walnut oil.

The invention does not add water when grinding the walnut kernels, so that the walnut kernels can be reduced in contact with water during the crushing process, and the degreasing rate of the walnut milk can be improved.

Preferably, the moisture content of the pretreated walnut kernels is 1% to 30%.

Preferably, the mass ratio of the crushed walnut kernels to water is 1:2 to 1:5.

Preferably, the enzymatic hydrolysis of the walnut pulp by the water enzymatic method specifically includes: heating the walnut pulp to 45°C to 55°C, adding protease, stirring and mixing, and the amount of protease added is based on the mass of the walnut kernel, which is 2% of the mass of the walnut kernel. ‰～5‰, react for 2h～3h, and obtain the walnut pulp after enzymolysis.

Preferably, the protease includes at least one of alkaline protease, neutral protease and papain.

The present invention only needs to carry out the enzymatic hydrolysis of the step-by-step reaction, and the reaction efficiency is high and the reaction time is short.

Preferably, the separation specifically includes: centrifuging the enzymatically hydrolyzed walnut pulp, and the centrifugation conditions are: centrifuging at 6000-10000 r/min for 5-15 minutes.

Preferably, the walnut kernel after the pretreatment comprises: the selection step of walnut kernel and the peeling step of walnut kernel:

The selection steps of the walnut kernels specifically include: selecting the walnut kernels with no mildew, no oily smell, no insect damage, no impurities, and full particles;

And/or, the peeling step of the walnut kernel specifically includes: using an alkaline boiling process to peel the walnut kernel and washing it with water;

The present invention obtains walnut raw materials with a certain moisture content by peeling the skin.

And/or, the alkaline boiling process includes: preparing an alkaline aqueous solution with a mass concentration of 2-6‰, adding walnut kernels after boiling, timing for 1-25 minutes, and washing the alkali-boiled walnut kernels with water to complete the peeling process.

Preferably, in the refining step that also includes walnut oil, specifically includes:

The walnut oil is subjected to hydration and degumming treatment to obtain hydrated and degummed walnut oil; the walnut oil after hydration and degumming is dehydrated to obtain dehydrated walnut oil; the decolorized walnut oil is decolorized and filtered to obtain decolorized walnut oil; the decolorized walnut oil is obtained by filtration. The oil is deodorized to obtain refined walnut oil.

Preferably, the hydration and degumming treatment specifically includes: heating the walnut oil to 50° C. to 70° C., stirring at 30 r/min to 100 r/min, and then standing for 2 to 4 hours to obtain the hydration and degumming walnut oil;

Because the water enzymatic method is adopted in the present invention, the walnut oil obtained after centrifugation contains water, and can be directly hydrated and degummed.

And/or, the dehydration treatment specifically includes: keeping the vacuum degree above 90kPa, heating the hydrated and degummed walnut oil to 60°C to 80°C, so that the moisture in the hydrated and degummed walnut oil is reduced to less than 0.11% to obtain dehydrated walnuts. The disappearance of oil and mist in the decolorizing pot indicates that the dehydration requirements have been met.

And/or, the decolorization treatment specifically includes: controlling the oil temperature of the dehydrated walnut oil at 50°C to 70°C, adding a decolorizing agent, and the amount of the decolorizing agent added is 3% to 5% of the weight of the dehydrated walnut oil, and the decolorization time is 30min. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the decolorizing agent is separated by a filter to obtain decolorized walnut oil.

Preferably, the decolorizing agent includes activated clay.

The deodorization treatment specifically includes: maintaining the oil temperature at 170-180° C. during deodorization, maintaining the vacuum degree above 90 kPa, and deodorizing time of 3-5 hours.

Preferably, the method further includes: filling with nitrogen after the refining step of the walnut oil to obtain filled walnut oil.

The technical scheme of the present invention has the following advantages:

(1) The present invention crushes walnut kernels under anhydrous conditions. By crushing the walnut kernels to a suitable particle size, the walnut kernels can obtain a better crushing effect, not only can the walnut oil existing between the walnut and the cells be released, but also the walnut oil in the walnut cells can be released together. At the same time, because it is carried out under anhydrous conditions, no water is introduced during the crushing process, which reduces the contact between water and walnut oil during the crushing process, and avoids walnut oil being emulsified by water as much as possible. The surface area thus increases the contact between the enzyme and the walnut and improves the enzymatic hydrolysis efficiency.

If the walnut kernel is broken by adding water, the oil yield is low; if the walnut kernel is broken without adding water, it can reach more than 70% under the same process conditions.

(2) The present invention adopts the water enzymatic method, which has low water requirements for walnut kernels. For example, the production of walnut oil by pressing method requires the water content of walnut kernels to be less than 5%; while the water content of walnut oil by water enzymatic method can have a wide range, such as 1% to 30%, or even higher water content, all can use water enzymatic method. The water enzymatic method can produce oil at a temperature of about 50 ° C for two hours; while the pressing method needs to be dried to less than 5%, and the energy is high.

(3) high efficiency: although there is also water enzymatic method to prepare walnut oil at present, but the present invention only needs to carry out a stepwise reaction enzymolysis by the water enzymatic method, and the reaction efficiency is high, the reaction time is short, and the enzymolysis efficiency is greatly improved , which provides a feasible experimental scheme for the preparation of walnut oil by water enzymatic method.

(4) The present invention adopts the water enzymatic method to prepare walnut oil, and the conditions are mild, which can prevent the generation of harmful substances such as aflatoxin and 3,4 benzopyrene in the original extraction technology, and does not add chemical antioxidants to achieve the original ecology. In the prior art, the oil is usually roasted at high temperature to produce a rich aroma. However, if the roasting temperature is too high or local scorching occurs, it is likely to produce aflatoxin, Harmful substances such as benzopyrene.

(5) Refining walnut oil: Because the present invention adopts the water enzymatic method to prepare walnut oil, there is still a part of water in the walnut oil, which can be directly hydrated and degummed without introducing water.

(6) The step of deacidification without alkali refining: because the enzymatic hydrolysis temperature of the present invention is carried out under the conditions of 45°C to 55°C, the conditions are mild, and there is basically no high temperature condition in the process of preparing walnut oil, which can well suppress free fatty acids appear. The stage of alkali refining and degumming is omitted, and the bad taste of saponification will not be introduced, and naturally there is no need for washing alkali.

Description of drawings

In order to illustrate the specific embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

If the specific experimental steps or conditions are not indicated in the examples, it can be carried out according to the operations or conditions of the conventional experimental steps described in the literature in this field. The reagents or instruments used without the manufacturer's indication are all conventional reagent products that can be obtained from the market.

Alkaline protease used in the examples of the present invention was purchased from Danisco Company, papain was purchased from German AB Enzyme Preparation Company and Novozymes Company, the enzyme activity was 800,000, and neutral protease was purchased from Novozymes Company.

Example 1

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:3.

Step 5: heating the walnut pulp to 50°C, adding alkaline protease, stirring and mixing, the amount of alkaline protease added is 3‰ of the mass of the walnut kernel based on the mass of the walnut kernel, and reacted for 2 hours to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Example 2

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:3.

Step 5: Heat the walnut pulp to 50°C, add papain, stir and mix, and the amount of papain added is 3‰ of the mass of the walnut kernel based on the mass of the walnut kernel, and react for 2 hours to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Example 3

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:3.

Step 5: heating the walnut pulp to 50°C, adding neutral protease, stirring and mixing, the amount of neutral protease added is 3‰ of the mass of the walnut kernel based on the mass of the walnut kernel, and reacted for 2 hours to obtain the enzymatic hydrolyzed walnut pulp.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Example 4

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the technological process is shown in Figure 1, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:3.

Step 5: heating the walnut pulp to 50°C, adding alkaline protease, stirring and mixing, the amount of alkaline protease added is 3‰ of the mass of the walnut kernel based on the mass of the walnut kernel, and reacted for 2 hours to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 60° C., stirring at 80 r/min, and standing for 3 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90kpa, heating the degummed walnut oil to 70°C, and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 60°C, add activated clay in an amount of 4% of the oil weight, and decolorize for 30 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 175° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 4 hours.

Step 11: Filling with nitrogen to improve the shelf life.

Example 5

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the technological process is shown in Figure 1, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:3.

Step 5: Heat the walnut pulp to 50°C, add alkaline protease, neutral protease and papain, stir and mix, the addition amount of alkaline protease, neutral protease and papain is based on the mass of walnut kernel, respectively 1‰, and the reaction was carried out for 2h to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 60° C., stirring at 80 r/min, and standing for 3 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90 kPa, heating the degummed walnut oil to 70° C., and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 60°C, add activated clay in an amount of 4% of the oil weight, and decolorize for 30 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 175° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 4 hours.

Step 11: Filling with nitrogen to improve the shelf life.

Example 6

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the technological process is shown in Figure 1, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:5.

Step 5: Heat the walnut pulp to 50°C, add alkaline protease, neutral protease and papain, stir and mix, the addition amount of alkaline protease, neutral protease and papain is based on the mass of walnut kernel, respectively 1‰, and the reaction was carried out for 2h to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 60° C., stirring at 80 r/min, and standing for 3 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90 kPa, heating the degummed walnut oil to 70° C., and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 60°C, add activated clay in an amount of 4% of the oil weight, and decolorize for 30 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 175° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 4 hours.

Step 11: Filling with nitrogen to improve the shelf life.

Example 7

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the technological process is shown in Figure 1, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:3.

Step 5: Heat the walnut pulp to 50°C, add alkaline protease, neutral protease and papain, stir and mix, the addition amount of alkaline protease, neutral protease and papain is based on the mass of walnut kernel, respectively 1.5‰, and reacted for 2h to obtain the walnut pulp after enzymolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 60° C., stirring at 80 r/min, and standing for 3 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90 kPa, heating the degummed walnut oil to 70° C., and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 60°C, add activated clay in an amount of 4% of the oil weight, and decolorize for 30 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 175° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 4 hours.

Step 11: Filling with nitrogen to improve the shelf life.

Example 8

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the technological process is shown in Figure 1, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 1%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:3.

Step 5: Heat the walnut pulp to 50°C, add alkaline protease, neutral protease and papain, stir and mix, the addition amount of alkaline protease, neutral protease and papain is based on the mass of walnut kernel, respectively 1‰, and the reaction was carried out for 2h to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 60° C., stirring at 80 r/min, and standing for 3 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90 kPa, heating the degummed walnut oil to 70° C., and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 60°C, add activated clay in an amount of 4% of the oil weight, and decolorize for 30 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 175° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 4 hours.

Step 11: Filling with nitrogen to improve the shelf life.

Example 9

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the technological process is shown in Figure 1, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 1%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:5.

Step 5: Heat the walnut pulp to 50°C, add alkaline protease, neutral protease and papain, stir and mix, the addition amount of alkaline protease, neutral protease and papain is based on the mass of walnut kernel, respectively 1‰, and the reaction was carried out for 2h to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 60° C., stirring at 80 r/min, and standing for 3 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90 kPa, heating the degummed walnut oil to 70° C., and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 60°C, add activated clay in an amount of 4% of the oil weight, and decolorize for 30 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 175° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 4 hours.

Step 11: Filling with nitrogen to improve the shelf life.

Example 10

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 2‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 30%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:5.

Step 5: Heat the walnut pulp to 45°C, add alkaline protease, neutral protease and papain, stir and mix, the addition amount of alkaline protease, neutral protease and papain is based on the mass of 1‰, and the reaction was carried out for 2h to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the walnut pulp after enzymolysis at 6000 r/min for 5 min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 50° C., stirring at 100 r/min, and standing for 4 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90 kPa, heating the degummed walnut oil to 80° C., and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 50°C, add activated clay in an amount of 5% of the oil weight, and decolorize for 20 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: the decolorized walnut oil is heated to 180°C, the vacuum degree is kept above 90kPa, and deodorization treatment is carried out, and the deodorization treatment time is 5h.

Step 11: Filling with nitrogen to improve the shelf life.

Example 11

The present embodiment provides a method for preparing walnut oil by water enzymatic method, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 6‰, add walnut kernels after boiling, time for 1 minute, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 1%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:2.

Step 5: Heat the walnut pulp to 55°C, add alkaline protease, neutral protease and papain, stir and mix, and the addition amount of alkaline protease, neutral protease and papain is based on the mass of 1.5‰, and the reaction was carried out for 3h to obtain the walnut pulp after enzymolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 15 minutes at 10,000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 70° C., stirring at 30 r/min, and standing for 2 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90 kPa, heating the degummed walnut oil to 80° C., and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 70°C, add activated clay in an amount of 3% of the oil weight, and decolorize the oil for 20 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is filtered by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 170° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 3h.

Step 11: Filling with nitrogen to improve the shelf life.

Comparative Example 1

The present comparative example provides a method for preparing walnut oil by an aqueous enzymatic method in which pretreated walnut kernels are broken by a colloid mill under the condition of adding water, and the specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: adding water to the peeled walnut kernels, wherein the mass ratio of walnut kernels to water is 1:3.

Step 4: use a colloid mill for crushing, and the particle size of the walnut kernel after crushing is not more than 900 μm.

Step 5: heating the walnut pulp to 50°C, adding alkaline protease, stirring and mixing, the amount of alkaline protease added is 3‰ of the mass of the walnut kernel based on the mass of the walnut kernel, and reacted for 2 hours to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatic hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 50° C., stirring at 30 r/min, and standing for 4 hours to obtain hydrated and degummed walnut oil.

Step 8: Dehydration of walnut oil: the degree of vacuum is kept above 90 kPa, the degummed walnut oil is heated to 60° C., and the moisture content is reduced to less than 0.11% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 50°C, add activated clay in an amount of 5% of the oil weight, and decolorize the oil for 40 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 170° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 3h.

Step 11: Filling with nitrogen to improve the shelf life.

Comparative Example 2

This comparative example provides a kind of method for preparing walnut oil by the water enzymatic method adopted after being broken, and the concrete steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: crushing the pretreated walnut kernels, and the average particle size of the crushed walnut kernels is 1500 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp, and the mass ratio of walnut kernels to water is 1:3.

Step 5: heating the walnut pulp to 50°C, adding alkaline protease, stirring and mixing, the amount of alkaline protease added is 3‰ of the mass of the walnut kernel based on the mass of the walnut kernel, and reacted for 2 hours to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatically hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 50° C., stirring at 30 r/min, and standing for 4 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90kPa, heating the degummed walnut oil to 60°C, and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 50°C, add activated clay in an amount of 5% of the oil weight, and decolorize for 20 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to below 40°C, and the oil is removed by a filter. Separated from decolorizers.

Step 10: The decolorized walnut oil is heated to 170° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 3h.

Step 11: Filling with nitrogen to improve the shelf life.

Comparative Example 3

This comparative example provides a method after colloid mill crushing and adding water, followed by homogenization. The specific steps are as follows:

Step 1: Choose 500g of walnut kernels with full particles, no mildew, no oily smell, no pests, and no impurities.

Step 2: prepare an alkaline aqueous solution with a mass concentration of 4‰, add walnut kernels after boiling, time for 25 minutes, rinse the alkali-boiled walnut kernels with water, and after rinsing, the obtained peeled walnut kernels have a moisture content of 20%.

Step 3: Using a colloid mill to crush the pretreated walnut kernels without adding water, and the particle size of the walnut kernels after crushing does not exceed 900 μm.

Step 4: Add water to the crushed walnut kernels to prepare walnut pulp. The mass ratio of walnut kernels to water is 1:3. The walnut pulp is heated to 55°C for homogenization, and the homogenization pressure is 20Mpa.

Step 5: heating the walnut pulp to 50°C, adding alkaline protease, stirring and mixing, the amount of alkaline protease added is 3‰ of the mass of the walnut kernel based on the mass of the walnut kernel, and reacted for 2 hours to obtain the walnut pulp after enzymatic hydrolysis.

Step 6: Centrifuge the enzymatically hydrolyzed walnut pulp for 10 minutes at 8000 r/min, and take the upper layer to obtain walnut oil.

Step 7: heating the walnut oil to 50° C., stirring at 30 r/min, and standing for 4 hours to obtain hydrated and degummed walnut oil.

Step 8: keeping the vacuum degree above 90kPa, heating the degummed walnut oil to 60°C, and reducing the moisture to 0.08% to obtain dehydrated walnut oil.

Step 9: Control the oil temperature of the dehydrated walnut oil at 50°C, add activated clay in an amount of 5% of the oil weight, and decolorize the oil for 30 minutes. After the decolorization is completed, the oil temperature is rapidly cooled to 40°C, and the oil is mixed with the oil by a filter. Decolorizer separation.

Step 10: The decolorized walnut oil is heated to 170° C., the vacuum degree is kept above 90 kPa, and deodorization treatment is performed, and the deodorization treatment time is 3h.

Step 11: Filling with nitrogen to improve the shelf life.

Experimental example 1

The second method of acid hydrolysis in "GB 5009.6-2016 National Food Safety Standard for the Determination of Fat in Foods" was used to measure the walnut kernels of Examples 1-11, the walnut oil isolated from Examples 1-11, and the cores of Comparative Examples 1-3. The fat content of the walnut oil separated from the walnut kernels and Comparative Examples 1 to 3 is defined as the calculation method of the oil yield: the percentage of the walnut oil in the original walnut kernel oil is obtained by separating the walnut pulp after enzymatic hydrolysis.

After calculation, the oil yield results are shown in Table 1:

Table 1 Oil yield results

Experimental example 2

No harmful substances were detected by headspace gas chromatography.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. And the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (10)

1. The method for preparing walnut oil by using the aqueous enzymatic method is characterized by comprising the following steps:

crushing the pretreated walnut kernels under the condition of not adding water, wherein the particle size of the crushed walnut kernels is less than or equal to 900 microns; adding water into the crushed walnut kernels to prepare walnut pulp; carrying out enzymolysis on the walnut pulp by using an aqueous enzymatic method; and separating the walnut pulp after enzymolysis to obtain the walnut oil.

2. The method for preparing walnut oil by using the aqueous enzymatic method as claimed in claim 1, wherein the water content of the pretreated walnut kernels is 1-30%.

3. The method for preparing walnut oil by the aqueous enzymatic method according to any one of claims 1 to 2, wherein the mass ratio of the crushed walnut kernels to water is 1:2 to 1: 5.

4. The method for preparing walnut oil by using the aqueous enzymatic method according to any one of claims 1 to 3, wherein the step of performing enzymatic hydrolysis on walnut slurry by using the aqueous enzymatic method specifically comprises: heating the walnut pulp to 45-55 ℃, adding protease, stirring and mixing, wherein the addition amount of the protease is 2-5 per mill of the mass of the walnut kernel by the mass of the walnut kernel, and reacting for 2-3 h to obtain the walnut pulp after enzymolysis.

5. The method for preparing walnut oil by using the aqueous enzymatic method of claim 4, wherein the protease comprises at least one of alkaline protease, neutral protease and papain.

6. The method for preparing walnut oil by using the aqueous enzymatic method according to any one of claims 1 to 5, wherein the separation specifically comprises: centrifuging the walnut pulp subjected to enzymolysis, wherein the centrifugation conditions are as follows: centrifuging for 5-15 min under the condition of 6000-10000 r/min.

7. The method for preparing walnut oil by using the aqueous enzymatic method according to any one of claims 1 to 6, wherein the pretreated walnut kernels comprise: selecting walnut kernels and peeling the walnut kernels:

the walnut kernel selection steps specifically comprise: selecting walnut kernels which are free from mildew, oil and rancid, insect pests and impurities and have full grains;

and/or the peeling step of the walnut kernels specifically comprises the following steps: peeling semen Juglandis by alkali cooking process, and washing with water;

and/or, the soda boiling process comprises: preparing an alkaline water solution with the mass concentration of 2-6 per mill, adding the walnut kernels after boiling, timing for 1-25 min, and washing the walnut kernels after alkaline boiling with water to finish the peeling process.

8. The method for preparing walnut oil by the aqueous enzymatic method according to any one of claims 1 to 7, further comprising a step of refining walnut oil;

optionally, the refining step comprises hydration degumming, dehydration, decolorization or deodorization treatment.

9. The method for preparing walnut oil by using the aqueous enzymatic method according to claim 8, wherein the hydration degumming treatment specifically comprises: heating the walnut oil to 50-70 ℃, stirring at 30-100 r/min, and standing for 2-4 h to obtain hydrated degummed walnut oil;

and/or the dehydration treatment specifically comprises: keeping the vacuum degree above 90kPa, heating the hydration degummed walnut oil to 60-80 ℃ to reduce the water content in the hydration degummed walnut oil to below 0.11 percent, and obtaining dehydrated walnut oil;

and/or the decoloring treatment specifically comprises the following steps: controlling the oil temperature of the dehydrated walnut oil at 50-70 ℃, adding a decoloring agent, wherein the adding amount of the decoloring agent is 3-5% of the weight of the dehydrated walnut oil, decoloring for 20-40 min, quickly cooling the oil temperature to be below 40 ℃ after decoloring, and separating the decoloring agent by using a filter to obtain the decolored walnut oil;

the deodorization treatment specifically comprises: the oil temperature is kept at 170-180 ℃ during deodorization, the vacuum degree is kept above 90kPa, and the deodorization time is 3-5 h.

10. The method for preparing walnut oil by using the aqueous enzymatic method according to any one of claims 8 to 9, further comprising: and (4) filling nitrogen after the walnut oil refining step to obtain the filled walnut oil.

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