A low temperature pressing process for increasing the linolenic acid content of perilla oil

Abstract

The invention discloses a low-temperature pressing process for increasing the linolenic acid content of perilla oil, comprising: wetting and adjusting the moisture content of cleaned perilla seeds to 10-12% to obtain wetted perilla seeds; conditioning the wetted perilla seeds for 30-60 minutes to obtain the tempered perilla seeds; subjecting the tempered perilla seeds to microwave treatment until the moisture content is 1-6% to obtain the microwave-treated perilla seeds, wherein the elasticity value of the microwave-treated perilla seeds is 0.76-0.85 and the destructive force is 8.5-15N; kneading the microwave-treated perilla seeds to obtain the kneaded perilla seeds, wherein the stacking angle of the kneaded perilla seeds is 26-31°; and pressing the kneaded perilla seeds to obtain perilla oil with high linolenic acid content. The process of the invention has a wide range of applications and is flexible in operation; the product has high purity and high recovery rate; the ALA content of perilla oil is increased, and the oil yield is guaranteed as much as possible.

Description

Technical Field

[0001] The invention belongs to the technical field of vegetable oil processing, and in particular relates to a low-temperature pressing process for increasing the linolenic acid content of perilla oil. Background Art

[0002] Perilla is one of the first batch of Chinese medicines for both medicinal and edible purposes issued by the Ministry of Health of my country. Perilla seeds are the seeds of Perilla, which are rich in oil. Perilla oil has a very high content of unsaturated fatty acids, mainly α-linolenic acid (ALA). ALA is the most important n-3 PUFA in the diet, which can participate in the synthesis of human phospholipids and can also be converted into DHA and EPA in the body. It has many physiological functions such as improving memory and regulating blood pressure. It is an important essential fatty acid for the human body.

[0003] At present, the human body's dietary ALA intake is relatively low. Therefore, increasing the ALA content of edible oil and the preparation of high-ALA edible oil are of great practical significance for enriching my country's oil products and increasing the daily dietary ALA intake of Chinese residents.

[0004] The existing methods for increasing the content of α-linolenic acid mainly use oil as raw material, and the main methods include: 1. Urea inclusion method, which uses fatty acids as raw materials for enrichment, that is, the oil must first be hydrolyzed to produce fatty acids, and then it can be enriched to increase the ALA content. Fatty acids cannot be eaten directly and need to be further processed into glycerides; 2. Molecular distillation method, which uses the different mean free paths of different types of molecules after escaping from the liquid surface (evaporation liquid surface) at high temperature to achieve separation and enrichment. It can not only directly separate oils and fats, but also be used for the separation of fatty acids or oil methyl esterification products after oil hydrolysis. However, this method uses a relatively high temperature, which is very easy to cause adverse side reactions such as oxidation and polymerization for perilla seed oil with a high ALA content, affecting the quality of edible oil.

[0005] In the current existing technology, it is difficult to achieve a high oil yield while taking into account the high ALA content in the hydraulic preparation of perilla seed oil. Summary of the invention

[0006] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a low-temperature pressing process for increasing the linolenic acid content of perilla oil.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: a low temperature pressing process for increasing the linolenic acid content of perilla oil, comprising:

[0010] Wetting and adjusting the moisture content of the cleaned and impurity-free perilla seeds to 10-12% to obtain wetted perilla seeds;

[0011] Conditioning the moistened perilla seeds for 30 to 60 minutes to obtain tempered perilla seeds;

[0012] The perilla seeds after the conditioning treatment are subjected to microwave treatment until the moisture content is 1-6%, so as to obtain the perilla seeds after the microwave treatment, wherein the elasticity value of the perilla seeds after the microwave treatment is 0.76-0.85 and the destructive force is 8.5-15N;

[0013] The microwave-treated perilla seeds are subjected to rubbing treatment to obtain rubbed perilla seeds, wherein the reposition angle of the rubbed perilla seeds is 26 to 31 degrees;

[0014] The kneaded perilla seeds are pressed to produce perilla oil with a high linolenic acid content.

[0015] As a preferred solution of the low-temperature pressing process for increasing the linolenic acid content of perilla oil according to the present invention, the drying is used to adjust the moisture content, wherein the drying temperature is 50-60°C.

[0016] As a preferred solution of the low-temperature pressing process for increasing the linolenic acid content of perilla oil according to the present invention, the tempering treatment comprises the following steps: the tempering treatment comprises a treatment temperature of 50 to 55° C. and a treatment time of 30 to 60 minutes.

[0017] As a preferred solution of the low-temperature pressing process for increasing the linolenic acid content of perilla oil according to the present invention, the microwave treatment comprises the following steps: the microwave treatment power is 200 to 350 W, the treatment time is 9 to 15 min, and the microwave treatment temperature is 30 to 45°C.

[0018] As a preferred scheme of the low-temperature pressing process for increasing the linolenic acid content of perilla oil described in the present invention, the oil is pressed to produce oil, wherein the pressing pressure is 10-20 MPa, the total pressing time is 20-40 min, and the number of pressing times is 2-3 times.

[0019] As a preferred solution of the low-temperature pressing process for increasing the linolenic acid content of perilla oil according to the present invention, the pressing pressure is 10 MPa.

[0020] As a preferred solution of the low-temperature pressing process for increasing the linolenic acid content of perilla oil according to the present invention, the total pressing time is 30 minutes and the pressing times are 2 times.

[0021] As a preferred solution of the low-temperature pressing process for increasing the linolenic acid content of perilla oil according to the present invention, the pressing temperature is 10-30°C.

[0022] Beneficial effects of the present invention:

[0023] (1) The present invention provides a low-temperature pressing process for increasing the linolenic acid content of perilla oil, which has a wide range of application and is flexible to operate; the product has high purity and high recovery rate; the ALA content of perilla oil is increased while the oil yield is guaranteed as much as possible;

[0024] (2) The present invention designs a preparation and processing method for increasing the ALA content of perilla seed oil based on the characteristics of the hydraulic extraction process of perilla seeds and the composition characteristics of perilla seeds and their oils. The elasticity value of the perilla seeds is made to be 0.76-0.85 and the destructive force is made to be 8.5-15N by optimizing the microwave treatment process. The reposition angle of the perilla seeds after the kneading treatment is made to be 26-31° by kneading treatment. The pressure of the oil press and the water content of the perilla seeds are combined to increase the ALA content of the perilla seed oil while taking into account the oil extraction rate. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0028] Evaluation index of the present invention:

[0029] The ALA content of perilla oil increases = XM; among them,

[0030] ——X represents the percentage of ALA in the prepared oil sample;

[0031] ——M, represents the percentage of ALA in perilla oil when it is squeezed multiple times at the maximum pressure until no oil flows out;

[0032] Determination of ALA percentage: After methyl esterification, the fatty acid composition of perilla oil was determined by GC, and the ALA percentage of perilla oil was calculated by area normalization method;

[0033] Perilla cake residual oil: Soxhlet extraction method.

[0034] Example 1

[0035] This embodiment provides a low-temperature pressing process for increasing the linolenic acid content of perilla oil, comprising:

[0036] (1) Wetting and adjusting the moisture content of cleaned and impurity-free perilla seeds to 12% to obtain wetted perilla seeds;

[0037] (2) conditioning the moistened perilla seeds at 55° C. for 40 min to obtain tempered perilla seeds;

[0038] (3) subjecting the tempered perilla seeds to microwave treatment until the moisture content is 1.3-13.6%, thereby obtaining microwave-treated perilla seeds, wherein the microwave treatment power is 230 W, the treatment time is 15 min, and the treatment temperature is 40° C.;

[0039] (4) kneading the microwave-treated perilla seeds to obtain kneaded perilla seeds, wherein the reposition angle of the kneaded perilla seeds is 30.8°;

[0040] (5) The kneaded perilla seeds are pressed to produce oil at a pressing pressure of 10 MPa, a total pressing time of 40 min, and a pressing number of 2 times (note: the perilla cakes are mixed before the next pressing), to obtain perilla oil with a high linolenic acid content.

[0041] The effects of different moisture contents on the ALA content and oil extraction rate of perilla seed oil after microwave treatment are shown in Table 1.

[0042] Table 1

[0043] Perilla seed moisture content, % 1.3 4.5 6.0 8.3 10.2 13.6 ALA content increased, % 6.2 6.1 6.9 6.0 5.2 4.6 Cake residue oil, % 19.1 18.7 18.5 19.2 19.6 25.7

[0044] As can be seen from Table 1, the moisture content of the perilla seeds after ultrasonic treatment is preferably 4.5-6%, achieving the best ALA extraction effect, while the residual oil in the cake is the lowest; it may be because the increase in the moisture content of the perilla seeds increases the hydrophilicity of non-lipid substances such as protein, sugar, and fiber, and the interaction between the perilla seeds and the more hydrophobic ALA in the perilla oil is weakened, which is beneficial to the precipitation of such oils, but excessive moisture may cause adverse side reactions leading to a decrease in ALA; at the same time, it affects the pressing performance of the perilla seeds - tissue structure, elasticity, adhesion, etc., and excessive moisture content may be unfavorable for the material to open the oil circuit to discharge oil, which not only affects the oil yield but also affects the ALA content.

[0045] Therefore, the present invention preferably sets the moisture content of the perilla seeds after ultrasonic treatment to 4.5-6%, so as to achieve the best ALA extraction effect and minimize the residual oil in the cake.

[0046] Example 2

[0047] This embodiment provides a low-temperature pressing process for increasing the linolenic acid content of perilla oil, comprising:

[0048] (1) Wetting and adjusting the moisture content of cleaned and impurity-free perilla seeds to 12% to obtain wetted perilla seeds;

[0049] (2) conditioning the moistened perilla seeds at 55° C. for 40 minutes to obtain tempered perilla seeds;

[0050] (3) subjecting the quenched and tempered perilla seeds to microwave treatment to obtain microwave-treated perilla seeds, wherein the microwave treatment is performed until the moisture content is 6%, wherein the elasticity value and destructive force of the microwave-treated perilla seeds are shown in Table 2;

[0051] (4) kneading the microwave-treated perilla seeds to obtain kneaded perilla seeds, wherein the reposition angle of the kneaded perilla seeds is 30.8°;

[0052] (5) The kneaded perilla seeds are pressed to produce oil at a pressing pressure of 10 MPa, a total pressing time of 40 min, and a pressing number of 2 times (note: the perilla cakes are mixed before the next pressing), to obtain perilla oil with a high linolenic acid content.

[0053] The effects of different conditioning parameters and microwave parameters on improving the ALA content and oil extraction rate of perilla seed oil are shown in Table 2.

[0054] Table 2

[0055]

[0056] The elasticity value and destructive force were determined using a texture analyzer and a cylindrical probe.

[0057] As can be seen from Table 2, different homogenization parameters and microwave treatment processes have a great influence on the ALA content and oil extraction rate of perilla seed oil. Among them, the elasticity value and destructive force are mainly due to the changes in the structure and performance of proteins, starch, etc. caused by the conditioning and microwave treatment process. The elasticity value and destructive force are the result of the joint action of multiple components of protein and starch. The elasticity value and destructive force are related to the compressive performance and crushing degree of perilla seeds in the oil production process. Insufficient crushing is not conducive to oil exudation, and too serious crushing will cause the perilla seeds to be too compact, which also affects the oil extraction effect. In order to ensure the effective improvement of ALA while taking into account the oil extraction rate, the preferred elasticity value of perilla seeds in the present invention is 0.76-0.85, and the preferred destructive force is 8.5-15N. Under this condition, the best ALA extraction effect is achieved, and the residual oil in the cake is the lowest. When it is not within the scope of the present invention, the effect is not good.

[0058] Example 3

[0059] This embodiment provides a low-temperature pressing process for increasing the linolenic acid content of perilla oil, comprising:

[0060] (1) Wetting and adjusting the moisture content of cleaned and impurity-free perilla seeds to 12% to obtain wetted perilla seeds;

[0061] (2) conditioning the moistened perilla seeds at 55° C. for 40 min to obtain tempered perilla seeds;

[0062] (3) subjecting the quenched and tempered perilla seeds to microwave treatment until the moisture content is 6%, thereby obtaining microwave-treated perilla seeds, wherein the microwave treatment power is 230 W, the treatment time is 15 min, the treatment temperature is 40° C., and the treated perilla seeds have an elasticity value of 0.85 and a destructive force of 8.54 N;

[0063] (4) kneading the microwave-treated perilla seeds to obtain kneaded perilla seeds, wherein the reposition angle of the kneaded perilla seeds is between 26.1° and 34.2°;

[0064] (5) The kneaded perilla seeds are pressed to produce oil at a pressing pressure of 10 MPa, a total pressing time of 40 min, and a pressing number of 2 times (note: the perilla cakes are mixed before the next pressing), to obtain perilla oil with a high linolenic acid content.

[0065] A wire brush (or a steel wool ball or a small stone with edges or other tools that can reduce the surface smoothness) is used to rub the perilla seeds to obtain a series of perilla seeds with different surface roughness (the surface roughness is characterized by the stacking angle). The parameters and results are shown in Table 3.

[0066] Table 3

[0067]

[0068] Determination of the repositories angle of perilla seeds: Use the static funnel method to pile up naturally, measure the repositories height and coverage radius, and calculate the repositories angle.

[0069] The larger the stacking angle, the rougher the surface of the perilla seeds, and the greater the friction between the particles. A certain friction can prevent the oil from slipping during the pressing process and affect the oil quality (ALA content and oil yield of the oil), but too much friction will lead to high energy consumption, which is not conducive to ensuring the oil output effect under the same pressure. That is, to obtain the same oil output effect, a greater pressure is required, so a certain stacking angle is sufficient. Therefore, the preferred stacking angle of the perilla seeds in the present invention is 28.9-30.8°.

[0070] Example 4

[0071] This embodiment provides a low-temperature pressing process for increasing the linolenic acid content of perilla oil, comprising:

[0072] (1) Wetting and adjusting the moisture content of cleaned and impurity-free perilla seeds to 12% to obtain wetted perilla seeds;

[0073] (2) conditioning the moistened perilla seeds at 55° C. for 40 min to obtain tempered perilla seeds;

[0074] (3) subjecting the quenched and tempered perilla seeds to microwave treatment until the moisture content is 6%, thereby obtaining microwave-treated perilla seeds, wherein the microwave treatment power is 230 W, the treatment time is 15 min, the treatment temperature is 40° C., and the treated perilla seeds have an elasticity value of 0.85 and a destructive force of 8.54 N;

[0075] (4) kneading the microwave-treated perilla seeds for 40 minutes to obtain kneaded perilla seeds, wherein the reposition angle of the kneaded perilla seeds is 30.8°;

[0076] (5) Pressing the kneaded perilla seeds to produce oil at a pressing pressure of 5 to 60 MPa for 40 min and twice (note: mix the perilla cakes before the next pressing) to obtain perilla oil with a high linolenic acid content.

[0077] The results of oil pressing at different pressures are shown in Table 4.

[0078] Table 4

[0079] Hydraulic oil pressing pressure, MPa 5 10 20 30 40 60 ALA content increased, % 6.4 6.9 4.9 3.1 1.0 0.5 Cake residue oil, % 24.1 18.5 17.2 16.9 16.5 16.2

[0080] Therefore, the pressure of the present invention is controlled at 5-30M, preferably 10-20MPa.

[0081] Example 5

[0082] This embodiment provides a low-temperature pressing process for increasing the linolenic acid content of perilla oil, comprising:

[0083] (1) Wetting and adjusting the moisture content of cleaned and impurity-free perilla seeds to 12% to obtain wetted perilla seeds;

[0084] (2) conditioning the moistened perilla seeds at 55° C. for 40 min to obtain tempered perilla seeds;

[0085] (3) subjecting the quenched and tempered perilla seeds to microwave treatment until the moisture content is 6%, thereby obtaining microwave-treated perilla seeds, wherein the microwave treatment power is 230 W, the treatment time is 15 min, the treatment temperature is 40° C., and the treated perilla seeds have an elasticity value of 0.85 and a destructive force of 8.54 N;

[0086] (4) kneading the microwave-treated perilla seeds for 40 minutes to obtain kneaded perilla seeds, wherein the reposition angle of the kneaded perilla seeds is 30.8°;

[0087] (5) Pressing the kneaded perilla seeds to produce oil at a pressing pressure of 10 MPa for a total pressing time of 10 to 60 min and 1 to 3 pressing times (note: when pressing multiple times, mix the perilla cakes before the next pressing) to obtain perilla oil with a high linolenic acid content.

[0088] The results are shown in Table 5.

[0089] Table 5

[0090] Time, min 10 10+10+10 15+15 30 20+20 40 20+20+20 60 ALA content increased, % 6.4 6.3 6.1 5.3 6.9 5.1 2.7 0.8 Cake residue oil, % 29.2 20.2 21.4 22.1 18.5 19.3 14.5 16.1

[0091] As can be seen from Table 5, the total pressing time is controlled to be 10 to 60 minutes. When the total pressing time is longer, multiple pressings are used, preferably 20 to 40 minutes, divided into 2 to 3 pressings.

[0092] During the hydraulic pressing process, the resistance to oil discharge from perilla seeds at different parts of the oil press is different. The material farther away from the oil outlet has greater resistance. Therefore, under the same total pressing time, appropriate pauses and turning the material over can help to evenly stress the material and achieve the adjustment and control of ALA content. During the hydraulic pressing process, the resistance to oil discharge from perilla seeds at different parts of the oil press is different. The material farther away from the oil outlet has greater resistance. Therefore, under the same total pressing time, appropriate pauses and turning the material over can help to evenly stress the material and achieve the adjustment and control of ALA content.

[0093] The low temperature in the present invention is the most commonly used process relative to existing oil mills, and the temperature of the oil pressing process is relatively high (the current low-temperature pressing standard stipulates that peanut oil pressing is kept below 70°C and rapeseed is kept below 90°C, which can be called low-temperature pressing. Usually, low-temperature pressing below 65°C to room temperature is used as a research target), so room temperature can be considered as low temperature.

[0094] The present invention provides a low-temperature pressing process for increasing the linolenic acid content of perilla oil, which has a wide range of application and is flexible in operation; the product has high purity and high recovery rate; the ALA content of perilla oil is increased while the oil yield is guaranteed as much as possible;

[0095] The invention designs a preparation and processing method for improving the ALA content of perilla seed oil according to the characteristics of the hydraulic preparation process of perilla seeds and the composition characteristics of perilla seeds and their oils. The elasticity value of the perilla seeds is 0.76-0.85 and the destructive force is 8.5-15N through an optimal microwave treatment process. The stacking angle of the perilla seeds after the kneading treatment is 26-31 degrees through a kneading treatment. The pressure of an oil press and the water content of the perilla seeds are combined to improve the ALA content of the perilla seed oil, while taking into account the oil extraction rate.

[0096] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A low temperature pressing process for increasing the linolenic acid content of perilla oil, characterized in that: include, Wetting and adjusting the moisture content of the cleaned and impurity-free perilla seeds to 10-12% to obtain wetted perilla seeds; The moistened perilla seeds are subjected to conditioning treatment to obtain the tempered perilla seeds, wherein the conditioning treatment temperature is 50-55° C. and the treatment time is 30-60 min; The tempered perilla seeds are subjected to microwave treatment until the moisture content is 1-6%, thereby obtaining microwave-treated perilla seeds, wherein the microwave treatment power is 200-350 W and the treatment time is 9-15 min; The microwave-treated perilla seeds are subjected to rubbing treatment to obtain rubbed perilla seeds, wherein the stacking angle of the rubbed perilla seeds is 26-31 degrees; The kneaded perilla seeds are pressed to obtain perilla oil with a high linolenic acid content, wherein the pressing pressure is 10-20 MPa, the total pressing time is 20-40 minutes, and the pressing times are 2-3 times.

2. The low temperature pressing process for increasing the linolenic acid content of perilla oil according to claim 1, characterized in that: The pressing pressure is 10 MPa.

3. The low temperature pressing process for increasing the linolenic acid content of perilla oil according to claim 1, characterized in that: The total pressing time is 30 minutes and the pressing times are 2 times.

4. The low temperature pressing process for increasing the linolenic acid content of perilla oil according to any one of claims 1 to 3, characterized in that: The pressing temperature is 10-30°C.

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