Soybean oil rich in vitamin E and free of trans-fatty acid and preparation method of soybean oil

Abstract

The invention discloses soybean oil rich in vitamin E and free of trans-fatty acid and a preparation method of the soybean oil. Soybeans are subjected to impurity removal, conditioning, softening, puffing, squeezing, degumming, decoloring and deodorization treatment to obtain the soybean oil, soybean deodorization distillate is extracted, and the extracted vitamin E is backfilled into the soybean oil, so that the content of the vitamin E in the soybean oil can be further increased.

Description

Technical Field

[0001] The invention relates to the technical field of edible oil processing, and more particularly to a soybean oil rich in vitamin E and containing zero trans fatty acids and a preparation method thereof. Background Art

[0002] Soybean oil is extracted from soybean seeds and is the most produced oil in the world. There are many types of soybean oil, which can be divided into pressed soybean oil and leached soybean oil according to the processing method. Because soybean oil is rich in nutritional value and is easy to obtain at a low cost, it is one of the most widely used edible oils.

[0003] Over-processing of soybean oil is particularly reflected in over-refining, that is, in the refining process, there are generally large amounts of alkali added, large amounts of clay added (10-20 kg of clay is used per ton of oil), high deodorization temperatures (240-260°C or even higher), and long deodorization times (2-3 hours). Over-refining not only wastes resources and energy, aggravates environmental pollution, and increases oil losses, but also removes most of the beneficial micronutrients naturally present in soybean oil, aggravates the loss of nutrients such as vitamin E, phytosterols, and squalene, and inevitably produces new harmful substances (such as trans fatty acids, glyceride polymers, etc.), which seriously reduces the nutritional and safety quality of soybean oil and creates new food safety issues.

[0004] These problems caused by excessive processing of soybean oil and the adverse effects on consumer health cannot be ignored.

[0005] Taking trans fatty acids as an example, according to surveys, the per capita trans fatty acid intake in my country is generally much lower than the 5.8g / day per capita in the United States. However, urban residents in my country generally consume highly refined salad oils and cooking oils for a long time, and foods containing hydrogenated vegetable oils are becoming more and more common. Fried foods are more popular among ordinary people, especially white-collar workers and children. Their tendency to westernize their diets has become increasingly obvious. The high intake of trans fatty acids objectively exists, which has caused certain harm to their physical and mental health. At the end of 2010, the domestic authoritative media reported that "the harm of trans fatty acids is greater than 666", which attracted widespread attention and strong response from the society. The safety of some edible oils was questioned, and ordinary consumers panicked, which had a major impact on my country's oil and food industry. This fully shows the breadth and severity of the impact of new and sudden public health events. Now the control of trans fatty acids has become the focus of the entire oil industry. It is very necessary to study and control the level of trans fatty acids in bulk oils such as soybean oil as soon as possible, so as to control it from the source. At present, major European and American countries have already made legislation on trans fatty acids, and limiting the content of trans fatty acids in food has become part of the food standard system of most advanced countries in the world. my country is also evaluating the level of trans fatty acids in oily foods, and it is imperative to formulate limit standards in the next step.

[0006] Increasing the content of naturally occurring vitamin E, sterols, squalene and other fat accompaniments in soybean oil has important health value. These ingredients have excellent antioxidant effects and other physiological functions. The U.S. Food and Nutrition Board (FNB) and the Chinese Nutrition Society recommend that adults should consume about 15 mg of α-vitamin E and at least 0.8 g of plant sterols per day (the amount of sterols per person from a normal diet is only 0.4-0.5 g per day) to reduce the risk of heart disease. According to the Chinese Nutrition Society's recommendation of 30 g of oil intake per day, if the vitamin E content in soybean oil reaches 1200 mg / kg and the sterol content reaches 2200 mg / kg, it can provide 6.1 mg of α-vitamin E and 66 mg of plant sterols, greatly alleviating the lack of these micronutrients in the Chinese people. Studies have shown that over-refining is the main step that causes the loss of vitamin E, sterols, etc. in soybean oil. The loss of vitamin E in soybean oil can reach 20% during alkali refining, and the loss of sterols caused by soapstock entrainment can reach 17%. Decolorization can lead to a loss of about 10% of vitamin E, and deodorization causes the loss of more than 20% of vitamin E and sterols. Summary of the invention

[0007] In view of this, the present invention provides a soybean oil rich in vitamin E and zero trans fatty acids and a preparation method thereof to solve the technical problems encountered in the background technology.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids comprises the following steps:

[0010] (1) removing impurities from soybeans by combined cleaning;

[0011] (2) conditioning the soybeans after impurities removal so that the maximum surface temperature reaches 70-90° C., and then cooling the surface of the soybeans to 20-30° C.;

[0012] (3) Soaking soybeans in clean water for 19-21 hours, draining the water and crushing the soybeans into soybean particles, and softening the soybean particles at 70-80° C. for 20-25 minutes;

[0013] (4) pressing the softened soybean particles into sheet-like soybean blanks, extruding and puffing the soybean blanks to produce puffed oil, and sending the puffed oil into an oil press for pressing to obtain crude oil and soybean cake;

[0014] (5) controlling the crude oil temperature to 72-74° C., performing acidification treatment, then cooling to 50-60° C., adjusting the pH, adding hot soft water of 1.0-2.0% by weight of the oil, 20-50 mg / kg of phospholipase A and 100-300 mg / kg of phospholipase C, mixing at high speed, entering an enzyme reaction tank and maintaining for 1.0-2.0 h, heating to 85° C., and centrifuging to separate the oil;

[0015] (6) adding the above oil to a decolorizing agent, placing it in a stirring kettle, stirring it at high speed, and then centrifuging it to remove the precipitate, thereby obtaining the decolorized oil for use;

[0016] (7) The decolorized oil is deoxygenated in a gasifier and then heated to 170-175° C., and then the oil is sent to a plate tower, and the oil is heated to 215-225° C. by high-temperature steam, and directly steam stripped for 10-15 minutes for thermal decolorization, and then the oil is sent to a packed tower, and the temperature is maintained at 215-225° C. for 5-8 minutes to remove fatty acids, and then the oil is sent to a plate tower to stay for 10-20 minutes, and finally the oil is cooled to 35-45° C. and then finely filtered to obtain the soybean oil rich in vitamin E and zero trans fatty acids.

[0017] Preferably, the combined cleaning in step (1) is cleaning through air separation, magnetic separation and stone removal, and the impurity content after cleaning is less than 0.5%.

[0018] Preferably, the tempering in step (2) is infrared tempering.

[0019] Preferably, the extrusion expansion temperature in step (4) is 150-210°C.

[0020] Preferably, the acidification treatment in step (5) is acidification with citric acid for 20-30 min;

[0021] The pH is adjusted to 4-5 using a sodium hydroxide solution with a volume concentration of 35%.

[0022] Preferably, the decolorizing agent in step (6) is an activated clay composite, and the activated clay composite is obtained by adding activated clay and polysilicate into a chitosan colloidal solution, mixing, and drying.

[0023] Preferably, the mass ratio of the activated clay, polysilicate and chitosan is: (5-10): (3-6): (1-4);

[0024] The chitosan is chitosan with a weight average molecular weight of 400,000 to 500,000 and a deacetylation degree greater than 85%; and the polysilicate is magnesium polysilicate or calcium polysilicate.

[0025] Preferably, the above steps further include: extracting natural vitamin E from the soybean deodorization distillate produced in step (7) and backfilling it into the soybean oil.

[0026] Preferably, the extraction is as follows: placing the soybean deodorized distillate into a supercritical extraction device, adjusting the extraction time to 2-5 hours, the extraction pressure to 14-18 MPa, the extraction temperature to 35-45°C, and the CO 2 The phytosterols were extracted at a flow rate of 1.5-2.5 mL / min.

[0027] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following technical effects:

[0028] (1) Phospholipase A (PLA), its degumming product lysophospholipid has good hydrophilicity and is easy to remove by water washing, but it takes too long, which brings difficulties to continuous operation, and the lysophospholipid is removed with the oil foot. Phospholipase C (PLC) can specifically hydrolyze the phosphorus-oxygen bond between the phosphate group and the glycerol group to generate diglyceride. Diaglyceride dissolves in oil and becomes part of the edible oil; the present invention utilizes the respective characteristics of PLC and PLA to develop a phospholipase C-phospholipase A dual enzyme degumming technology, that is, first use a small amount of PLA for conventional enzymatic degumming operation, use lysophospholipids to form an emulsified system that is conducive to the subsequent action of PLC, and then add an appropriate amount of PLC to implement the degumming operation;

[0029] (2) The present invention uses a composite material comprising chitosan, polysilicate and activated clay as a decolorizing adsorbent. Since the decolorizing adsorbent can effectively adsorb aldehyde compounds, peroxides and colored substances in soybean oil, it can not only effectively reduce the impurity content in the oil, but also inhibit the formation of 3-MCPD esters and glycidyl esters;

[0030] (3) The present invention extracts soybean deodorization distillate and then backfills the extracted vitamin E into soybean oil, thereby further increasing the vitamin E content in soybean oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing soybean oil rich in vitamin E and zero trans fatty acids, comprising the following steps:

[0036] (1) The soybeans are cleaned by air separation, magnetic separation and stone removal, and the impurity content after cleaning is less than 0.5%;

[0037] (2) The soybeans after impurity removal were subjected to infrared conditioning for 5 minutes to make the maximum surface temperature reach 90°C, and then the surface of the soybeans was cooled to 30°C;

[0038] (3) Soak the soybeans in clean water for 21 h, drain the water and crush them into soybean particles, and soften the soybean particles at 80°C for 25 min;

[0039] (4) pressing the softened soybean particles into sheet-like soybean blanks, extruding and puffing the soybean blanks at 210° C. to produce puffed oil, and sending the puffed oil into an oil press for pressing to obtain crude oil and soybean cake;

[0040] (5) The crude oil temperature is controlled at 74° C., acidified with citric acid for 20 min, then cooled to 60° C., and the pH value is adjusted to 5 with a sodium hydroxide solution having a volume concentration of 35%. At the same time, hot soft water with a weight of 2.0% of the oil, 50 mg / kg of phospholipase A and 300 mg / kg of phospholipase C are added, mixed at high speed, placed in an enzyme reaction tank and kept for 2.0 h, and then heated to 85° C. and centrifuged to separate the oil;

[0041] (6) adding the above oil to a decolorizing agent, placing it in a stirring kettle, stirring it at high speed, and then centrifuging it to remove the precipitate, thereby obtaining the decolorized oil for use;

[0042] (7) The decolorized oil is deoxygenated by a gasifier and then heated to 175°C. The oil is then sent to a plate tower, where it is heated to 225°C by high-temperature steam, and directly steam stripped for 15 minutes for thermal decolorization. The oil is then sent to a packed tower, where it is kept at 225°C for 8 minutes to remove fatty acids. The oil is then sent to a plate tower and allowed to stay for 20 minutes. Finally, the oil is cooled to 45°C and then finely filtered to obtain soybean oil rich in vitamin E and zero trans fatty acids.

[0043] (8) extracting natural vitamin E from the soybean deodorization distillate produced in step (7) and backfilling it into the soybean oil, wherein the extraction is as follows: placing the soybean deodorization distillate into a supercritical extraction device, adjusting the extraction time to 5 h, the extraction pressure to 18 MPa, the extraction temperature to 45° C., and the CO 2 The phytosterols were extracted at a flow rate of 2.5 mL / min.

[0044] In this embodiment, the decolorizing agent in step (6) is an activated clay composite, which is obtained by adding activated clay and polysilicate into a chitosan colloidal solution, mixing, and drying.

[0045] The mass ratio of activated clay, polysilicate and chitosan is 10:6:4;

[0046] The chitosan is chitosan with a weight average molecular weight of 500,000 and a deacetylation degree greater than 85%; the polysilicate is magnesium polysilicate or calcium polysilicate.

[0047] The soybean oil was tested for indicators, and the results were as follows: Vitamin E 1462 mg / kg; trans fatty acids 0%.

[0048] Example 2

[0049] This embodiment provides a method for preparing soybean oil rich in vitamin E and zero trans fatty acids, comprising the following steps:

[0050] (1) The soybeans are cleaned by air separation, magnetic separation and stone removal, and the impurity content after cleaning is less than 0.5%;

[0051] (2) The soybeans after impurity removal were subjected to infrared conditioning for 5 minutes to make the maximum surface temperature reach 70°C, and then the surface of the soybeans was cooled to 20°C;

[0052] (3) Soak the soybeans in clean water for 19 h, drain the water and crush them into soybean particles, and soften the soybean particles at 70°C for 20 min;

[0053] (4) pressing the softened soybean particles into sheet-like soybean blanks, extruding and puffing the soybean blanks at 150° C. to produce puffed oil, and sending the puffed oil into an oil press for pressing to obtain crude oil and soybean cake;

[0054] (5) The crude oil temperature is controlled at 72° C., acidified with citric acid for 20 min, then cooled to 50° C., and the pH value is adjusted to 4 with a sodium hydroxide solution having a volume concentration of 35%. At the same time, hot soft water with a weight of 1.0% of the oil, 20 mg / kg phospholipase A and 100 mg / kg phospholipase C are added, mixed at high speed, placed in an enzyme reaction tank and kept for 1.0 h, and then heated to 85° C. and centrifuged to separate the oil;

[0055] (6) adding the above oil to a decolorizing agent, placing it in a stirring kettle, stirring it at high speed, and then centrifuging it to remove the precipitate, thereby obtaining the decolorized oil for use;

[0056] (7) The decolorized oil is deoxygenated by a gasifier and then heated to 170°C. The oil is then sent to a plate tower, where it is heated to 215°C by high-temperature steam, and directly steam stripped for 10 minutes for thermal decolorization. The oil is then sent to a packed tower, where it is kept at 215°C for 5 minutes to remove fatty acids, and then sent to a plate tower to stay for 10 minutes. Finally, the oil is cooled to 35°C and then finely filtered to obtain soybean oil rich in vitamin E and zero trans fatty acids.

[0057] (8) extracting natural vitamin E from the soybean deodorization distillate produced in step (7) and backfilling it into the soybean oil, wherein the extraction is as follows: placing the soybean deodorization distillate into a supercritical extraction device, adjusting the extraction time to 2 h, the extraction pressure to 14 MPa, the extraction temperature to 35 ° C, and the CO 2 The phytosterols were extracted at a flow rate of 1.5 mL / min.

[0058] In this embodiment, the decolorizing agent in step (6) is an activated clay composite, which is obtained by adding activated clay and polysilicate into a chitosan colloidal solution, mixing, and drying.

[0059] The mass ratio of activated clay, polysilicate and chitosan is 5:3:1;

[0060] The chitosan is chitosan with a weight average molecular weight of 400,000 and a deacetylation degree greater than 85%; the polysilicate is magnesium polysilicate or calcium polysilicate.

[0061] The soybean oil was tested for indicators, and the results were as follows: Vitamin E 1551 mg / kg; trans fatty acids 0%.

[0062] Example 3

[0063] This embodiment provides a method for preparing soybean oil rich in vitamin E and zero trans fatty acids, comprising the following steps:

[0064] (1) The soybeans are cleaned by air separation, magnetic separation and stone removal, and the impurity content after cleaning is less than 0.5%;

[0065] (2) The soybeans after impurity removal were subjected to infrared conditioning for 5 minutes to make the maximum surface temperature reach 80°C, and then the surface of the soybeans was cooled to 25°C;

[0066] (3) Soak the soybeans in clean water for 20 h, drain the water and crush them into soybean particles, and soften the soybean particles at 75°C for 22 min;

[0067] (4) pressing the softened soybean particles into sheet-like soybean blanks, extruding and puffing the soybean blanks at 180° C. to produce puffed oil, and sending the puffed oil into an oil press for pressing to obtain crude oil and soybean cake;

[0068] (5) The crude oil temperature was controlled at 73° C., acidified with citric acid for 25 min, then cooled to 55° C., and the pH value was adjusted to 4 with a sodium hydroxide solution having a volume concentration of 35%. At the same time, 1.5% of the weight of the oil, 35 mg / kg of phospholipase A and 200 mg / kg of phospholipase C were added, mixed at high speed, placed in an enzyme reaction tank and kept for 1.5 h, and then heated to 85° C. and centrifuged to separate the oil;

[0069] (6) adding the above oil to a decolorizing agent, placing it in a stirring kettle, stirring it at high speed, and then centrifuging it to remove the precipitate, thereby obtaining the decolorized oil for use;

[0070] (7) The decolorized oil is deoxygenated by a gasifier and then heated to 173°C. The oil is then sent to a plate tower, where it is heated to 220°C by high-temperature steam, and directly steam stripped for 13 minutes for thermal decolorization. The oil is then sent to a packed tower, where it is kept at 220°C for 6 minutes to remove fatty acids. The oil is then sent to a plate tower and allowed to stay for 15 minutes. Finally, the oil is cooled to 40°C and then finely filtered to obtain soybean oil rich in vitamin E and zero trans fatty acids.

[0071] (8) extracting natural vitamin E from the soybean deodorization distillate produced in step (7) and backfilling it into the soybean oil, wherein the extraction is as follows: placing the soybean deodorization distillate into a supercritical extraction device, adjusting the extraction time to 3 h, the extraction pressure to 16 MPa, the extraction temperature to 40° C., and the CO 2 The phytosterols were extracted at a flow rate of 2 mL / min.

[0072] In this embodiment, the decolorizing agent in step (6) is an activated clay composite, which is obtained by adding activated clay and polysilicate into a chitosan colloidal solution, mixing, and drying.

[0073] The mass ratio of activated clay, polysilicate and chitosan is 8:4:2;

[0074] The chitosan is chitosan with a weight average molecular weight of 450,000 and a deacetylation degree greater than 85%; the polysilicate is magnesium polysilicate or calcium polysilicate.

[0075] The soybean oil was tested for indicators, and the results were as follows: vitamin E 1615 mg / kg; trans fatty acids 0%.

[0076] Comparative Example 1

[0077] This comparative example provides a method for preparing soybean oil, which is the same as that of Example 1, except that step (8) is omitted.

[0078] The soybean oil prepared in Comparative Example 1 was tested for indicators, and the results were as follows: vitamin E 1215 mg / kg; trans fatty acid 0%.

[0079] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0080] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids, characterized in that: The following steps are involved: (1) removing impurities from soybeans by combined cleaning; (2) conditioning the soybeans after impurities removal so that the maximum surface temperature reaches 70-90° C., and then cooling the surface of the soybeans to 20-30° C.; (3) Soaking soybeans in clean water for 19-21 hours, draining the water and crushing the soybeans into soybean particles, and softening the soybean particles at 70-80° C. for 20-25 minutes; (4) pressing the softened soybean particles into sheet-like soybean blanks, extruding and puffing the soybean blanks to produce puffed oil, and sending the puffed oil into an oil press for pressing to obtain crude oil and soybean cake; (5) controlling the crude oil temperature to 72-74° C., performing acidification treatment, then cooling to 50-60° C., adjusting the pH, adding hot soft water of 1.0-2.0% by weight of the oil, 20-50 mg / kg of phospholipase A and 100-300 mg / kg of phospholipase C, mixing at high speed, entering an enzyme reaction tank and maintaining for 1.0-2.0 h, heating to 85° C., and centrifuging to separate the oil; (6) adding the above oil to a decolorizing agent, placing it in a stirring kettle, stirring it at high speed, and then centrifuging it to remove the precipitate, thereby obtaining the decolorized oil for use; (7) The decolorized oil is deoxygenated in a gasifier and then heated to 170-175° C., and then the oil is sent to a plate tower, and the oil is heated to 215-225° C. by high-temperature steam, and directly steam stripped for 10-15 minutes for thermal decolorization, and then the oil is sent to a packed tower, and the temperature is maintained at 215-225° C. for 5-8 minutes to remove fatty acids, and then the oil is sent to a plate tower to stay for 10-20 minutes, and finally the oil is cooled to 35-45° C. and then finely filtered to obtain the soybean oil rich in vitamin E and zero trans fatty acids.

2. The method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids according to claim 1, characterized in that: The combined cleaning in step (1) is cleaning through air separation, magnetic separation and stone removal, and the impurity content after cleaning is less than 0.5%.

3. The method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids according to claim 1, characterized in that: The conditioning in step (2) is infrared conditioning.

4. The method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids according to claim 1, characterized in that: The extrusion expansion temperature in step (4) is 150-210°C.

5. The method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids according to claim 1, characterized in that: The acidification treatment in step (5) is carried out by using citric acid for 20-30 minutes; the pH adjustment is carried out by using a sodium hydroxide solution with a volume concentration of 35% to adjust the pH to 4-5.

6. The method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids according to claim 1, characterized in that: The decolorizing agent in step (6) is an activated clay composite, which is obtained by adding activated clay and polysilicate into a chitosan colloidal solution, mixing, and drying.

7. The method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids according to claim 6, characterized in that: The mass ratio of the activated clay, polysilicate and chitosan is: (5-10): (3-6): (1-4); the chitosan has a weight average molecular weight of 400,000-500,000 and a deacetylation degree greater than 85%; and the polysilicate is magnesium polysilicate or calcium polysilicate.

8. The method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids according to claim 1, characterized in that: Also includes: The natural vitamin E is extracted from the soybean deodorization distillate produced in step (7) and then backfilled into the soybean oil.

9. The method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids according to claim 8, characterized in that: The extraction is as follows: putting the soybean deodorized distillate into a supercritical extraction device, adjusting the extraction time to 2-5h, the extraction pressure to 14-18MPa, the extraction temperature to 35-45°C, and the CO2 flow rate to 1.5-2.5mL / min to extract the phytosterols.

10. A soybean oil rich in vitamin E and containing zero trans fatty acids, characterized in that: The soybean oil is prepared by the method for preparing soybean oil rich in vitamin E and containing zero trans fatty acids as described in any one of claims 1 to 9.

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