A method for preparing fragrant pecan oil

Abstract

The present invention discloses a method for producing fragrant pecan oil, belonging to the field of food processing technology. The method comprises wet-degumming pecan kernels, rapidly dehydrating them using microwaves, then flavoring them using medium- and short-wave infrared methods, and finally hydraulically pressing and oil refining to produce high-quality pecan oil. The method achieves excellent degumming effects and can remove a large amount of brown pigment from pecan kernels. It also shortens pecan kernel pretreatment time, reduces energy consumption, and imparts a unique flavor to the pecan oil. This method produces high-quality pecan oil with a light color, clarity, low acidity, good oxidative stability, and rich content of beneficial active ingredients.

Description

Technical Field

[0001] The invention relates to a method for preparing fragrant pecan oil, and belongs to the technical field of food processing. Background Art

[0002] Pecans (also known as American pecans, carya illinoensiskoch), native to the United States and northern Mexico, are the fruit of the American pecan tree and are also known as the "longevity fruit." Pecans contain 65% to 73% oil, with over 90% of the oil being unsaturated fatty acids. Pecan oil is also rich in trace active ingredients such as vitamin E, squalene, and polyphenols.

[0003] In 2020, the pecan acreage in my country reached nearly 800,000 mu (approximately 1,000 acres), and is projected to reach over 1 million mu (approximately 1,000,000 acres) in the coming years. Annual pecan production is expected to reach 100,000 tons. Faced with my country's enormous market demand for edible oils and fats, and the public's growing nutritional and health needs, pecans are poised to serve as a valuable edible oil and fat supplier.

[0004] Currently, there are few products related to pecan oil, and this small oil variety is typically processed through either cold pressing or hot pressing. Cold pressing involves directly pressing the kernels at low temperatures without pre-processing the oil. This method avoids the damage of high temperatures to the oil and reduces the generation of harmful factors. However, the resulting cake meal contains a high level of residual oil and has a relatively light flavor, which is not in line with Chinese edible oil consumption habits. Meanwhile, fragrant oils are currently primarily flavored through high-temperature steaming and stir-frying. However, this process involves prolonged, high-temperature steaming in a wok, which severely damages the protein in the cake meal and the trace active substances in the oil. The resulting crude oil is dark in color, has a high acidity, and produces a series of harmful factors, posing various threats to public health.

[0005] Therefore, it is necessary to develop a new process for the flexible production of high-quality pecan oil based on pecans, so as to obtain pecan oil with good flavor and rich in natural nutrients on the one hand, and high-quality pecan protein meal on the other hand to facilitate its application in food. Summary of the Invention

[0006]

Technical Issues

[0007] The technical problem actually to be solved by the present invention is to provide a method for flexibly preparing high-quality fragrant pecan oil.

[0008]

Technical solution

[0009] In order to solve the above problems, the present invention provides a flexible method for producing high-quality fragrant pecan oil, which overcomes the problems of high damage to oil and fat caused by traditional high-temperature pretreatment, loss of beneficial accompanying substances in oil and fat caused by traditional refining, and poor flavor of cold-pressed oil and fat.

[0010] The flexible method for preparing high-quality fragrant pecan oil of the present invention comprises the following steps: pecan kernels are wet-undressed, then treated under microwave conditions to quickly remove moisture from the oil, and then subjected to medium- and short-wave infrared aroma enhancement to impart a special flavor to the pecan kernels, destroy the oil body structure, and promote the dissolution of fat-soluble beneficial components.

[0011] The method for flexibly preparing high-quality fragrant pecan oil of the present invention comprises the following steps: subjecting the fragranced pecan kernels to gradient-increased hydraulic pressing to obtain oil, and refining the oil through processes such as filtration, low-temperature crystallization and freeze filtration to obtain high-quality pecan oil.

[0012] The first object of the present invention is to provide a method for stripping pecan kernels, wherein the method comprises soaking the pecan kernels in a dilute alkaline solution, then stripping the kernels using a pecan kernel stripping machine, and then rinsing the kernels with clean water.

[0013] In one embodiment of the present invention, the pecan kernel peeling conditions are as follows: the pecan kernels are soaked in alkaline solution for 3 to 7 minutes at a soaking temperature of 60° C. to 80° C., and then peeled in a pecan peeling machine for 5 to 8 minutes.

[0014] In one embodiment of the present invention, the alkali solution is prepared from sodium hydroxide and / or sodium bicarbonate with a concentration of 0.5% to 1.5%.

[0015] A second object of the present invention is to provide a method for preparing pecan oil and / or pecan protein meal, comprising: taking peeled pecan kernels, rapidly dehydrating them using microwaves, then flavoring them using medium- and short-wave infrared methods, and finally hydraulically pressing and refining the oil to obtain high-quality pecan oil and pecan protein meal.

[0016] In one embodiment of the present invention, the microwave rapid dehydration conditions are: microwave treatment temperature 95° C. to 115° C., treatment time 0.15 h to 1 h.

[0017] In one embodiment of the present invention, the conditions for medium- and short-wave infrared fragrance enhancement are: the short-wave infrared wavelength range is 0.78 μm to 2.5 μm, the medium-wave infrared wavelength range is 2.5 μm to 10 μm, the ratio of short-wave infrared lamp power to medium-wave infrared lamp power is 1:1 to 1:2, the temperature is 120°C to 150°C, and the time is 25 min to 45 min.

[0018] In one embodiment of the present invention, the hydraulic pressing conditions are as follows: the maximum pressing pressure is 40Mpa to 60Mpa, the pressing method is a gradient pressurization method, the pressure is increased by 0.5Mpa to 1.5Mpa per minute, and the final pressure is maintained for 3min to 5min.

[0019] In one embodiment of the present invention, the oil refining conditions are: after the crude oil is filtered, it is subjected to low-temperature crystallization and freeze filtration; the freeze crystallization conditions are: from room temperature to 5°C to 10°C, and the cooling gradient is 0.5°C to 1.5°C / min.

[0020] The third object of the present invention is to provide a fragrant pecan oil and pecan protein meal prepared by the above method.

[0021] A fourth object of the present invention is to provide a use of pecan oil and / or pecan protein meal in the preparation of food, cosmetics or medicines.

[0022] In one embodiment of the present invention, the food comprises edible oil, beverage, ice cream, cream, protein powder, and baked goods.

[0023] Beneficial effects of the present invention:

[0024] The pecan kernel peeling method of the present invention has good peeling effect, and the peeling rate can reach more than 90%. In addition, a large amount of pigment in the pecan kernel can be removed, thereby reducing the decolorization process in subsequent oil processing.

[0025] The method can obtain high-quality pecan oil; the oil has a lighter color, a rich flavor, is clear and transparent, has a low acid value, has good oxidation stability, and is rich in beneficial active ingredients.

[0026] The invention adopts microwave rapid dehydration and medium and short wave infrared to perform aroma enhancement, which can quickly remove moisture from pecan kernels and enhance the aroma of the pecan kernels, giving the pecan kernels a special aroma; at the same time, the pre-treatment time can be greatly shortened and energy consumption can be reduced.

[0027] The present invention uses a grease refining method that combines hydraulic pressing with low-temperature crystallization and freeze filtration to remove impurities such as colloid in the grease, reduce the loss of beneficial natural nutrients in the grease, shorten the grease refining process, and reduce energy consumption. DETAILED DESCRIPTION

[0028] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0029] 1. Test method of acid value:

[0030] The acid value of oils and fats was tested according to GB 5009.229-2016.

[0031] 2. Test method for oxidation stability:

[0032] The oxidative stability index (OSI) of oils and fats was tested according to GB / T 21121-2007. 3 g of oil sample (accurate to 0.001 g) was added to a glass test tube and measured using a Rancimat oil oxidation stability analyzer. The test temperature was 120°C and the air flow rate was 20 L / h. The OSI value of the oil sample was expressed in h. Each test was repeated three times, and the average results were calculated.

[0033] 3. Chromatic Aberration

[0034] The measurement was performed using a fully automatic colorimeter.

[0035] 4. Vitamin E testing method:

[0036] The vitamin E content in oils and fats was tested with reference to GB 5009.82-2016.

[0037] 5. Testing method of squalene:

[0038] The squalene content in oils and fats was tested with reference to LS / T 6120-2017.

[0039] Example 1: A method for preparing fragrant pecan oil and pecan protein meal

[0040] 100 kg of pecan kernels were soaked in a 1% sodium hydroxide solution (temperature 65°C) for 5 minutes, and then detached using a pecan peeler for 5 minutes. After detaching, the kernels were washed with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for treatment at 100°C for 0.5 hours, and then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for aroma enhancement at 130°C for 30 minutes. The aroma enhanced pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 50 MPa and a pressure increase rate of 1 MPa / min. After the pressure increase was completed, the pressure was maintained for 4 minutes to obtain pecan oil and pecan protein meal. The obtained pecan oil was filtered and transferred to a refrigerated tank. The temperature was cooled from room temperature to 10°C at a rate of 1°C / min and maintained for 24 hours. After crystallization and sedimentation, the kernels were filtered to obtain fragrant pecan oil.

[0041] Comparative Example 1:

[0042] 100 kg of pecan kernels were placed in a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for aroma enhancement at a treatment temperature of 130°C for 30 min. The aroma enhanced pecan kernels were placed in a hydraulic oil press for pressing at a pressure of 50 MPa and a pressure increase rate of 1 MPa / min. After the pressure increase was completed, the pressure was maintained for 4 min to obtain pecan oil and pecan protein meal. The obtained pecan oil was filtered and transferred to a cold storage tank, where the temperature was lowered from room temperature to 10°C at a cooling rate of 1°C / min and maintained for 24 h. After crystallization and sedimentation were completed, the pecan oil was obtained after filtration.

[0043] Comparative Example 2:

[0044] 100 kg of pecan kernels were soaked in a 1% sodium hydroxide solution (temperature 65°C) for 5 minutes, and then detached using a pecan peeler for 5 minutes. After detaching, the kernels were washed with clean water and centrifuged to remove water. The kernels were then placed in an oven for treatment at 100°C for 1.5 hours, and then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for aromatization at 130°C for 30 minutes. The aromatized pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 50 MPa and a pressure increase rate of 1 MPa / min. After the pressure increase was completed, the pressure was maintained for 4 minutes to obtain pecan oil and pecan protein meal. The obtained pecan oil was filtered and transferred to a refrigerated tank. The temperature was cooled from room temperature to 10°C at a rate of 1°C / min and maintained for 24 hours. After crystallization and sedimentation, the kernels were filtered to obtain pecan oil.

[0045] Comparative Example 3:

[0046] 100 kg of pecan kernels are soaked in a 1% sodium hydroxide solution (temperature 65° C.) for 5 minutes, and then stripped using a pecan stripper for 5 minutes. After stripping, the kernels are cleaned with clean water and centrifuged to remove water, and then placed in a microwave device for treatment for 0.5 hours at a treatment temperature of 100° C., and then transferred to a wok for flavoring at a temperature of 130° C. for 30 minutes; the flavored pecan kernels are placed in a hydraulic oil press for pressing at a pressing pressure of 50 MPa and a pressure increasing rate of 1 MPa / min, and the pressure is maintained for 4 minutes after the pressure increasing is completed, to obtain pecan oil and pecan protein meal; the obtained pecan oil is filtered, transferred to a cold storage tank, and cooled from room temperature to 10° C. at a cooling rate of 1° C. / min and maintained for 24 hours. After crystallization and sedimentation, the kernels are filtered to obtain the pecan oil.

[0047] Table 1 Test results of acid value, flavor and color of pecan oil obtained in Example 1 and Comparative Examples 1 to 3

[0048]

[0049]

[0050] Table 2 Test results of oxidative stability, VE and squalene of pecan oil obtained in Example 1 and Comparative Examples 1 to 3

[0051]

[0052] Table 3 Flavor and color test results of pecan protein meal obtained in Example 1 and Comparative Examples 1 to 3

[0053]

[0054] Example 2: A method for preparing fragrant pecan oil

[0055] 100 kg of pecan kernels were soaked in a 2% sodium bicarbonate solution (temperature 70°C) for 7 minutes, and then detached using a pecan peeler for 7 minutes. After detaching, the kernels were washed with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for treatment at 95°C for 0.8 hours, and then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for aroma enhancement at 120°C for 40 minutes. The aroma enhanced pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 55 MPa and a pressure increase rate of 1 MPa / min. After the pressure increase was completed, the pressure was maintained for 3 minutes to obtain pecan oil and pecan protein meal. The obtained pecan oil was filtered and transferred to a refrigerated tank. The temperature was cooled from room temperature to 10°C at a rate of 1°C / min and maintained for 24 hours. After crystallization and sedimentation, the kernels were filtered to obtain fragrant pecan oil.

[0056] Comparative Example 4:

[0057] 100 kg of pecan kernels were soaked in a 2% sodium bicarbonate solution (temperature 70°C) for 7 minutes, and then detached using a pecan peeler for 7 minutes. After detaching, the kernels were washed with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for 10.8 hours at a treatment temperature of 95°C, and then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 2:1) for aroma enhancement at a treatment temperature of 120°C for 40 minutes. The aroma enhanced pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 55 MPa and a pressure increase rate of 1 MPa / min. After the pressure increase was completed, the pressure was maintained for 3 minutes to obtain pecan oil and pecan protein meal. The obtained pecan oil was filtered and transferred to a refrigerated tank. The temperature was cooled from room temperature to 10°C at a cooling rate of 1°C / min and maintained for 24 hours. After crystallization and sedimentation, the kernels were filtered to obtain fragrant pecan oil.

[0058] Comparative Example 5:

[0059] 100 kg of pecan kernels were soaked in a 2% sodium bicarbonate solution (temperature 70°C) for 7 minutes, and then detached using a pecan peeler for 7 minutes. After detaching, the kernels were washed with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for treatment at 95°C for 0.8 hours, and then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:3) for aroma enhancement at 120°C for 40 minutes. The aroma enhanced pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 55 MPa and a pressure increase rate of 1 MPa / min. After the pressure increase was completed, the pressure was maintained for 3 minutes to obtain pecan oil and pecan protein meal. The obtained pecan oil was filtered and transferred to a refrigerated tank. The temperature was cooled from room temperature to 10°C at a rate of 1°C / min and maintained for 24 hours. After crystallization and sedimentation, the kernels were filtered to obtain fragrant pecan oil.

[0060] Comparative Example 5:

[0061] 100 kg of pecan kernels were soaked in a 2% sodium bicarbonate solution (temperature 70°C) for 7 minutes. After soaking, the kernels were stripped using a pecan stripper for 7 minutes. After stripping, the kernels were washed with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for treatment at 95°C for 0.8 hours. The kernels were then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for aroma enhancement at 120°C for 40 minutes. The aroma enhanced pecan kernels were placed in a screw oil press for pressing to obtain pecan oil and pecan protein meal. The obtained pecan oil was filtered and transferred to a refrigerated tank. The temperature was cooled from room temperature to 10°C at a rate of 1°C / min and maintained for 24 hours. After crystallization and sedimentation, the kernels were filtered to obtain fragrant pecan oil.

[0062] Comparative Example 6:

[0063] 100 kg of pecan kernels were soaked in a 2% sodium bicarbonate solution (temperature 70°C) for 7 minutes, and then detached using a pecan nut stripper for 7 minutes. After detaching, the kernels were washed with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for treatment at 95°C for 0.8 hours, and then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for aromatization at 120°C for 40 minutes. The aromatized pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 55 MPa and a pressure increase rate of 1 MPa / min. After the pressure increase was completed, the pressure was maintained for 3 minutes to obtain pecan oil and pecan protein meal. The obtained crude pecan oil was degummed, deacidified, decolorized, and deodorized to obtain pecan finished oil.

[0064] Table 4 Test results of acid value, flavor and beneficial components of pecan oil obtained in Example 2 and Comparative Examples 4 to 6

[0065]

[0066]

[0067] Example 3: A method for preparing pecan protein meal

[0068] 100 kg of pecan kernels were soaked in a 0.5% sodium hydroxide solution (temperature 70°C) for 6 minutes. After soaking, the kernels were detached using a pecan peeler for 6 minutes. After detaching, the kernels were cleaned with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for treatment at a temperature of 105°C for 0.4 hours. The kernels were then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for aromatization at a temperature of 125°C for 25 minutes. The aromatized pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 50 MPa and a pressure increase rate of 0.5 MPa / min. After the pressure increase was completed, the pressure was maintained for 3 minutes to obtain pecan oil and pecan protein meal.

[0069] Comparative Example 8:

[0070] 100 kg of pecan kernels were soaked in a 0.5% sodium hydroxide solution (temperature 70°C) for 6 minutes, and then detached using a pecan peeler for 6 minutes. After detaching, the kernels were washed with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for treatment for 0.4 hours at a treatment temperature of 105°C, and then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for flavoring at a treatment temperature of 100°C for 25 minutes. The flavored pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 50 MPa and a pressure increase rate of 0.5 MPa / min. After the pressure increase was completed, the pressure was maintained for 3 minutes to obtain pecan oil and pecan protein meal.

[0071] Comparative Example 9:

[0072] 100 kg of pecan kernels were soaked in a 0.5% sodium hydroxide solution (temperature 70°C) for 6 minutes. After soaking, the kernels were detached using a pecan peeler for 6 minutes. After detaching, the kernels were cleaned with clean water and centrifuged to remove water. The kernels were then placed in a microwave device for treatment at a temperature of 105°C for 0.4 hours. The kernels were then transferred to a medium- and short-wave infrared device (short- and medium-wave infrared power ratio = 1:2) for flavoring at a temperature of 160°C for 25 minutes. The flavored pecan kernels were placed in a hydraulic oil press for pressing at a pressing pressure of 50 MPa and a pressure increase rate of 0.5 MPa / min. After the pressure increase was completed, the pressure was maintained for 3 minutes to obtain pecan oil and pecan protein meal.

[0073] Table 5 Flavor and color test results of pecan protein meal obtained in Example 3 and Comparative Examples 8-9

[0074]

[0075] Comparative Example 10

[0076] Referring to Example 1, the sodium hydroxide concentration was changed to 0% and 3%, while other conditions remained unchanged. When the sodium hydroxide concentration was 0%, the peeling rate of pecans in clear water was about 60%; when the alkali solution concentration was greater than 2%, the pecans had a serious color reversion phenomenon and a darker color.

[0077] Comparative Example 11

[0078] Referring to Example 1, the peeling treatment time was changed to 2 minutes and 10 minutes, while other conditions remained unchanged. When the treatment time was less than 3 minutes, most of the pecans were not peeled; when the treatment time was greater than 7 minutes, the kernels were dyed and the color became darker.

[0079] Comparative Example 12

[0080] Referring to Example 1, without stripping, and with other conditions unchanged, the obtained oil has a darker color and a higher residual oil content.

[0081] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for improving the quality of fragrant pecan oil, characterized in that: The method comprises the following steps: wet-dressing pecan kernels, rapidly dehydrating the kernels by microwaves, adding fragrance by medium- and short-wave infrared methods, and finally hydraulically pressing and refining the oil to obtain high-quality pecan oil. The wet peeling process for pecan kernels is as follows: the pecan kernels are soaked in an alkaline solution for 3 to 7 minutes at a temperature of 60°C to 80°C, and then peeled in a pecan peeling machine for 5 to 8 minutes; the alkaline solution is prepared from sodium hydroxide and / or sodium bicarbonate at a concentration of 0.5% to 1.5%. The microwave rapid dehydration conditions are as follows: microwave treatment temperature 95°C to 115°C, treatment time 0.15 h to 1 h; The conditions for the medium- and short-wave infrared fragrance enhancement are as follows: the short-wave infrared wavelength range is 0.78 μm to 2.5 μm, the medium-wave infrared wavelength range is 2.5 μm to 10 μm, the treatment time is 25 minutes to 45 minutes; the lamp power ratio of the short-wave infrared to medium-wave infrared is 1:1 to 1:2, and the temperature is 120°C to 150°C; The hydraulic pressing conditions are as follows: the maximum pressing pressure is 40 MPa to 60 MPa, the pressing method is a gradient pressurization method, the pressure is increased by 0.5 MPa to 1.5 MPa per minute, and the final pressure is maintained for 3 minutes to 5 minutes; The oil refining conditions are as follows: after filtering the crude oil, it is subjected to low-temperature crystallization and freeze filtration; the freeze crystallization conditions are: from room temperature to 5°C ~ 10°C, with a cooling gradient of 0.5°C ~ 1.5°C / min.

2. The method according to claim 1, characterized in that The steps include: 100 kg of pecan kernels were soaked in a 1% sodium hydroxide solution at 65°C for 5 minutes. After soaking, the kernels were stripped in a pecan stripper for 5 minutes. After stripping, the kernels were rinsed with clean water and centrifuged to remove water. The kernels were then placed in a microwave oven for 0.5 hours at 100°C. They were then transferred to a medium- and short-wave infrared device for aroma enhancement at 130°C for 30 minutes. The lamp power ratio of the medium- and short-wave infrared device was 1:

2. The flavored pecan kernels were placed in a hydraulic oil press and pressed at a pressing pressure of 50 MPa and a pressure increasing rate of 1 MPa / min. After the pressure increasing was completed, the pressure was maintained for 4 minutes to obtain pecan oil and pecan protein meal. The obtained pecan oil was filtered and transferred to a cold storage tank. The temperature was lowered from room temperature to 10°C at a rate of 1°C / min and maintained for 24 hours. After crystallization and sedimentation, the fragrant pecan oil was obtained after filtration. The oxidative stability of pecan oil is 6.6 h / 121.6℃, the VE content is 26.4 mg / 100g, and the squalene content is 252.0 mg / kg.

3. A method for improving the protein quality of fragrant pecans, characterized in that: The method according to claim 1 is used to collect pecan protein meal obtained by hydraulic pressing; the protein meal has the inherent flavor and taste of pecans, and is rich in flavor; and is grayish white in color.

4. The pecan oil and pecan protein meal prepared by the method according to any one of claims 1 to 3.

5. Use of the pecan oil and pecan protein meal according to claim 4 in the preparation of food, cosmetics or medicines.

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