A kind of organic pecan oil and production method thereof

Abstract

The present invention provides a method for producing organic pecan oil, and belongs to the technical field of vegetable oil production. The present invention adopts a water enzymatic method to extract pecan oil through a two-step enzymatic hydrolysis process, and the method includes: pecan kernels are ground with water after roasting to obtain a slurry; the pH of the slurry is adjusted to alkaline, and alkaline protease and α-amylase are added for enzymatic hydrolysis to obtain a first enzymatic hydrolyzate; the pH of the first enzymatic hydrolyzate is adjusted to acidic, and acidic protease is added for enzymatic hydrolysis to obtain a second enzymatic hydrolyzate; the second enzymatic hydrolyzate is inactivated and centrifuged, and the upper free oil is taken, which is pecan oil. The method of the present invention can effectively improve the extraction rate of pecan oil, and the content of phenolic acid substances and flavonoid substances in the obtained pecan oil is relatively high.

Description

Technical Field

[0001] The invention belongs to the technical field of vegetable oil production, and in particular relates to organic pecan oil and a production method thereof. Background Art

[0002] Pecan (Caryacathayensis Sarg.) belongs to the genus CaryaNutt in the Juglandaceae family. It is one of the tree nuts with the longest planting history and is mainly distributed in eastern North America and southeastern Asia. The main producing areas of pecan in my country are Lin'an, Anji in Zhejiang Province, Jixi and Ningguo in Anhui Province. Pecan fruit is rich in nutrition and has high economic benefits. It is one of the varieties with higher nutritional value among many dried fruits in my country. Pecan contains rich polyphenols, including monomeric polyphenols and polymeric polyphenols, such as flavonoids and phenolic acids. The fatty acids in pecan oil are mainly oleic acid. Oleic acid is a monounsaturated fatty acid with strong stability. It has the effects of lowering blood lipids and cholesterol, preventing and treating cardiovascular diseases and atherosclerosis, and anti-oxidation. Therefore, pecan oil has high nutritional and health value.

[0003] Pressing and solvent extraction are the mainstream processes for producing vegetable oils. Before pressing or extraction, the oil needs to be crushed, pulverized, pressed or baked to destroy the cell structure of the oil by mechanical and thermal methods to achieve favorable oil extraction conditions. Although these methods have a high oil yield, the equipment is complex, and more importantly, they cause protein denaturation, so that the cake after oil extraction cannot be effectively utilized, resulting in a serious waste of protein resources. In addition, a desolventizing process is required after solvent extraction, which requires a lot of equipment, large investment, and heavy pollution. Therefore, in order to overcome the drawbacks of traditional oil production processes, considering economic, environmental, and safety factors, the water enzyme method for extracting vegetable oils came into being.

[0004] The aqueous enzyme method uses mechanical and enzymatic hydrolysis as means to degrade plant cell walls. On the basis of mechanical crushing, the oil is treated with enzymes that have a degrading effect on oil tissues and complexes such as lipopolysaccharides and lipoproteins. The enzyme further destroys the cell structure and the enzyme decomposes lipoproteins and lipopolysaccharides to increase the fluidity of the oil in the oil tissue, thereby freeing the oil. However, there are many factors that affect the process of extracting vegetable oil by the aqueous enzyme method, and the process conditions such as the type of enzyme required for different oils, enzymatic hydrolysis conditions, and oil treatment methods are also different. Therefore, how to use the aqueous enzyme method to efficiently extract pecan oil is one of the technical problems to be solved in this field. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for producing organic pecan oil, which can effectively improve the extraction rate of pecan oil, and the obtained pecan oil has a high content of phenolic acids and flavonoids.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides a method for producing organic pecan oil, which comprises: roasting pecan kernels, adding water and grinding to obtain slurry; adjusting the pH of the slurry to alkaline, adding a composite enzyme for enzymolysis to obtain a first enzymolysis solution; adjusting the pH of the first enzymolysis solution to acidic, adding an acidic protease for enzymolysis to obtain a second enzymolysis solution; inactivating the enzyme in the second enzymolysis solution, centrifuging, and taking the upper free oil to obtain the pecan oil;

[0008] The complex enzyme is composed of alkaline protease and alpha-amylase in a mass ratio of 1-3:1-3.

[0009] Preferably, the pecan kernels are roasted at 60-80° C. to a moisture content of ≤5%.

[0010] Preferably, based on the mass of roasted pecan kernels, the amount of water added during grinding is 10 to 20 mL / g.

[0011] Preferably, the pH value of the slurry is 7.2-8.5.

[0012] Preferably, based on the mass of roasted pecan kernels, the added amount of the complex enzyme is 500-1000 U / g; the enzymolysis temperature is 45-65° C., and the enzymolysis time is 100-220 min.

[0013] Preferably, the pH of the first enzymatic hydrolysis solution is 5.8-6.4.

[0014] Preferably, based on the mass of roasted pecan kernels, the added amount of the acidic protease is 200-600 U / g; the enzymolysis temperature is 40-55° C., and the enzymolysis time is 60-180 min.

[0015] Preferably, the enzyme inactivation temperature is 85-90° C., and the enzyme inactivation time is 15-30 min.

[0016] Preferably, the centrifugal conditions are 2500-3000 r / min, 15-20 min.

[0017] The invention also provides pecan oil prepared by the production method.

[0018] Beneficial effects of the present invention:

[0019] The invention adopts an aqueous enzymatic method, optimizes the aqueous enzymatic extraction process and parameters, and adds hydrolases in steps, and adopts a two-step enzymatic hydrolysis process to extract pecan oil, so that the extraction rate of pecan oil can be effectively improved, and the contents of phenolic acid substances and flavonoid substances in the obtained pecan oil are high, the content of phenolic acid substances is 87.46 mg / 100 g in terms of gallic acid, and the content of flavonoid substances is 114.95 mg / 100 g in terms of rutin.

[0020] The method of the present invention is simple to operate, low in cost, suitable for industrial production, and conducive to large-scale production and promotion. DETAILED DESCRIPTION

[0021] The invention provides a method for producing organic pecan oil, which comprises: roasting pecan kernels, adding water and grinding to obtain slurry; adjusting the pH of the slurry to alkaline, adding a composite enzyme for enzymolysis to obtain a first enzymolysis solution; adjusting the pH of the first enzymolysis solution to acidic, adding an acidic protease for enzymolysis to obtain a second enzymolysis solution; inactivating the enzyme in the second enzymolysis solution, centrifuging, and taking the upper free oil to obtain the pecan oil;

[0022] The pecan kernels described in the present invention are pecan kernels with the attached skin removed. As an optional embodiment, the present invention adds the walnut kernels to be peeled into hot water at a temperature of 70 to 80° C., soaks for 10 to 15 minutes, and then uses a high-pressure water gun to rinse the walnut kernels with cool water, and through the kneading and flushing of the high-pressure water, the kernel skin of the walnut kernels is completely removed, and the pecan kernels with the attached skin removed are obtained for standby use.

[0023] The present invention bakes the pecan kernels after removing the skin, and the pecan kernels are baked at 60-80° C. until the moisture content is less than 5%. The baking temperature is preferably 65-75° C., more preferably 70° C.

[0024] The present invention grinds the roasted pecan kernels with water to obtain a slurry, and the amount of water added for grinding is 10 to 20 mL / g, preferably 12 to 17 mL / g, and more preferably 14 to 15 mL / g, based on the mass of the roasted pecan kernels. As an optional embodiment, the present invention grinds the pecan kernels with a grinder to obtain a slurry.

[0025] The pH value of the slurry is adjusted to 7.2 to 8.5, preferably 7.5 to 8.2, more preferably 7.8 to 8. As an optional embodiment, the pH value of the slurry is adjusted using sodium hydroxide.

[0026] The present invention adds a composite enzyme to the slurry after adjusting the pH for enzymolysis to obtain a first enzymolysis solution. The composite enzyme of the present invention is composed of alkaline protease: α-amylase according to a mass ratio of 1 to 3: 1 to 3, and the mass ratio of alkaline protease: α-amylase in the composite enzyme is preferably 1: 1. Based on the mass of roasted pecan kernels, the addition amount of the composite enzyme of the present invention is 500 to 1000 U / g, preferably 600 to 880 U / g, and more preferably 850 to 800 U / g. The enzymolysis temperature of the present invention is 45 to 65°C, preferably 48 to 60°C, and more preferably 52 to 56°C; the enzymolysis time is 100 to 220 min, preferably 145 to 200 min, and more preferably 160 to 185 min. The present invention can effectively increase the dissolution amount of oil from cells through the first stage of enzymolysis.

[0027] The present invention adjusts the pH of the first enzymatic hydrolyzate to 5.8 to 6.4, preferably 5.9 to 6.2, more preferably 6 to 6.1. As an optional embodiment, the present invention uses hydrochloric acid to adjust the pH of the slurry.

[0028] The present invention adds an acidic protease to the first enzymolysis solution after adjusting the pH to perform enzymolysis to obtain a second enzymolysis solution. Based on the mass of the roasted pecan kernels, the amount of the acidic protease added in the present invention is 200-600U / g, preferably 300-500U / g, and more preferably 350-450U / g. The enzymolysis temperature of the present invention is 40-55°C, preferably 42-52°C, and more preferably 45-50°C; the enzymolysis time is 60-180min, preferably 80-145min, and more preferably 100-120min. The present invention can further promote the dissolution of oil from cells through the first stage of enzymolysis, and at the same time can reduce the emulsification degree of the enzymolysis solution and improve the extraction rate of oil.

[0029] The present invention performs enzyme inactivation treatment on the second enzymolysis solution, the enzyme inactivation temperature is 85-90°C, preferably 86-88°C, the enzyme inactivation time is 15-30min, preferably 20-25min, and more preferably 22min. The enzyme inactivation solution is naturally cooled to room temperature, and then centrifuged, and the centrifugation conditions are 2500-3000r / min, 15-20min, preferably 2800r / min, 17-18min. After the centrifugation treatment, the upper free oil is taken, which is pecan oil.

[0030] The invention also provides pecan oil prepared by the production method, and the pecan oil can be used in the food industry or added in cosmetics.

[0031] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0032] In the following embodiments, unless otherwise specified, all of them are conventional methods.

[0033] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0034] Example 1

[0035] A production method of organic pecan oil:

[0036] (1) Peeling of pecan kernels: Add the walnut kernels to be peeled into 75°C hot water, with the water just enough to cover the kernels. Maintain the water temperature at 75°C and soak for 12 minutes. Then drain the water and use a high-pressure water gun to rinse the kernels with cool water. Repeat the rinsing until the kernel skins are completely removed.

[0037] (2) Baking: Place the pecan kernels on a tray and bake them in an oven at 70°C, turning them over in the middle. The moisture content of the baked pecan kernels is 4%.

[0038] (3) Grinding: Grind the pecan kernels and water in a ratio of 1 g:15 mL using a grinder to obtain a slurry.

[0039] (4) Adjusting the pH of the slurry: Use 1 M sodium hydroxide to adjust the pH of the slurry to 8.

[0040] (5) The first step of enzymatic hydrolysis: based on the mass of roasted pecan kernels, 800 U / g of complex enzyme was added to the slurry, wherein the complex enzyme consisted of alkaline protease and α-amylase in a mass ratio of 1:1; enzymatic hydrolysis was performed at 60° C. for 200 min to obtain the first enzymatic hydrolyzate.

[0041] (6) Adjusting the pH of the first enzymatic hydrolysis solution: Using 1 M hydrochloric acid, adjust the pH of the first enzymatic hydrolysis solution to 6.

[0042] (7) Second enzymatic hydrolysis: Based on the mass of roasted pecan kernels, 400 U / g of acidic protease was added to the slurry; enzymatic hydrolysis was performed at 50° C. for 120 min to obtain the second enzymatic hydrolyzate.

[0043] (8) Inactivation of enzyme and centrifugation: The second enzymatic hydrolysate is kept at 90°C for 20 min, and then the enzymatic hydrolysate is centrifuged at 2500 r / min for 20 min. The free oil in the upper layer is obtained, which is pecan oil.

[0044] Example 2

[0045] The difference between this embodiment and embodiment 1 is that in step (2), the pecan kernels are placed on a tray and baked in an oven at 75° C., turning the kernels over in the middle, and the moisture content of the baked pecan kernels is 5%.

[0046] Example 3

[0047] The difference between this embodiment and embodiment 1 is that in step (3), a grinder is used to grind pecan kernels and water at a ratio of 1 g:12 mL to obtain a slurry.

[0048] Example 4

[0049] The only difference between this embodiment and embodiment 1 is that in step (4), 1 M sodium hydroxide is used to adjust the pH of the slurry to 7.5.

[0050] Example 5

[0051] The difference between this embodiment and embodiment 1 is that in step (5), 1000 U / g of complex enzyme is added to the slurry based on the mass of roasted pecan kernels.

[0052] Example 6

[0053] The only difference between this embodiment and embodiment 1 is that in step (5), the composite enzyme is composed of alkaline protease and α-amylase in a mass ratio of 1:3.

[0054] Example 7

[0055] The only difference between this embodiment and embodiment 1 is that in step (5), the composite enzyme is composed of alkaline protease and α-amylase in a mass ratio of 3:1.

[0056] Example 8

[0057] The only difference between this embodiment and embodiment 1 is that in step (5), the enzymolysis temperature is 50° C. and the enzymolysis time is 220 min.

[0058] Example 9

[0059] The only difference between this embodiment and embodiment 1 is that in step (6), 1 M hydrochloric acid is used to adjust the pH of the first enzymatic hydrolysis solution to 5.8.

[0060] Example 10

[0061] The difference between this embodiment and embodiment 1 is that: in step (7), based on the mass of roasted pecan kernels, 600 U / g of acid protease is added to the slurry;

[0062] Embodiment 11

[0063] The only difference between this embodiment and embodiment 1 is that in step (7), the enzymolysis temperature is 45° C. and the enzymolysis time is 100 min.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that in step (3), a grinder is used to grind pecan kernels and water at a ratio of 1 g:25 mL to obtain a slurry.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that in step (4), 1 M sodium hydroxide is used to adjust the pH of the slurry to 6.5.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 1 is that in step (4), 1 M sodium hydroxide is used to adjust the pH of the slurry to 9.

[0070] Comparative Example 4

[0071] The difference between this comparative example and Example 1 is that in step (5), the composite enzyme is composed of alkaline protease and α-amylase in a mass ratio of 1:5.

[0072] Comparative Example 5

[0073] The difference between this comparative example and Example 1 is that in step (5), the composite enzyme is composed of alkaline protease and α-amylase in a mass ratio of 5:1.

[0074] Comparative Example 6

[0075] The difference between this comparative example and Example 1 is that in step (5), the composite enzyme consists of papain and α-amylase in a mass ratio of 1:1.

[0076] Comparative Example 7

[0077] The difference between this comparative example and Example 1 is that in step (5), the composite enzyme is composed of alkaline protease and papain in a mass ratio of 1:1.

[0078] Comparative Example 8

[0079] The difference between this comparative example and Example 1 is that in step (5), the composite enzyme is composed of neutral protease and papain in a mass ratio of 1:1.

[0080] Comparative Example 9

[0081] The difference between this comparative example and Example 1 is that the pH of the first enzymatic hydrolysis solution is not adjusted, and the acidic protease is directly added to carry out the second step of enzymatic hydrolysis.

[0082] Comparative Example 10

[0083] The difference between this comparative example and Example 1 is that in step (7), the acidic protease is replaced by papain.

[0084] Comparative Example 11

[0085] The difference between this comparative example and Example 1 is that in step (5), based on the mass of roasted pecan kernels, 800 U / g of complex enzyme and 400 U / g of acid protease are added to the slurry at the same time, enzymolysis is carried out at 60° C. for 350 min, and the enzymolysis solution is inactivated and centrifuged. The inactivation / centrifugation conditions are the same as those in Example 1.

[0086] The methods of Example 1 and Comparative Examples 1 to 11 were used to extract pecan oil, and the oil yield, extraction rate and total phenol content were calculated. The results are shown in Table 1.

[0087] Oil yield determination method: Pecan oil yield (%) = (free oil mass / pecan kernel mass) × 100.

[0088] Extraction rate determination method: pecan oil extraction rate (%) = free oil mass / (pecan kernel mass × pecan kernel oil content) × 100.

[0089] Table 1 Oil yield, extraction rate and total phenol content of different methods

[0090]

[0091] As can be seen from Table 1, the present invention adopts the aqueous enzymatic method and extracts pecan oil through a two-step enzymatic hydrolysis process, which can effectively increase the oil yield of pecan oil to 70.17%, and the extraction rate can reach 97.46%. The content of phenolic acids and flavonoids in the obtained pecan oil is relatively high. The content of phenolic acids is 87.46 mg / 100 g in terms of gallic acid, and the content of flavonoids is 114.95 mg / 100 g in terms of rutin.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for producing organic pecan oil, characterized in that: The method comprises: roasting pecan kernels, adding water and grinding to obtain slurry; adjusting the pH of the slurry to alkaline, adding a composite enzyme for enzymolysis to obtain a first enzymolysis solution; adjusting the pH of the first enzymolysis solution to acidic, adding an acidic protease for enzymolysis to obtain a second enzymolysis solution; after the second enzymolysis solution is inactivated and centrifuged, the upper free oil is taken, which is pecan oil; The complex enzyme is composed of alkaline protease and α-amylase in a mass ratio of 1:1; Based on the mass of roasted pecan kernels, the amount of water added during grinding is 10-20 mL / g; The pH value of the slurry is 7.2-8.5; Based on the mass of roasted pecan kernels, the addition amount of the complex enzyme is 500-1000 U / g; the enzymolysis temperature of the complex enzyme is 45-65° C., and the enzymolysis time is 100-220 min; The pH of the first enzymatic hydrolysate is 5.8-6.4; Based on the mass of roasted pecan kernels, the added amount of the acidic protease is 200-600 U / g; the enzymolysis temperature of the acidic protease is 40-55° C., and the enzymolysis time is 60-180 min.

2. The production method according to claim 1, characterized in that The pecan kernels are roasted at 60-80° C. until the moisture content is ≤5%.

3. The production method according to claim 1, characterized in that The enzyme inactivation temperature is 85-90° C., and the enzyme inactivation time is 15-30 min.

4. The production method according to claim 1, characterized in that The centrifugal conditions are 2500-3000 r / min, 15-20 min.

5. The pecan oil prepared by the production method according to any one of claims 1 to 4.

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