Zero-reflection green accurate moderately-processed wheat germ oil and preparation method thereof

Abstract

The invention provides zero-reflection green, accurate and moderately processed wheat germ oil and a preparation method thereof. Specifically, the invention provides a method for reducing the phosphorus content of oil in the refining process of wheat germ oil, and the method comprises the steps of acid-method degumming, enzyme-method degumming and the like. Wherein in the acid process degumming, the use amount of acid is 2000-5000 mg of acid per kilogram of oil weight. The invention also provides a method for reducing the acid value and the free fatty acid content of the grease in the wheat germ oil refining process, and simultaneously enabling the VE retention rate of the grease to be greater than or equal to 90% and the sterol retention rate to be greater than or equal to 93%, and the method sequentially comprises an acid method degumming step, an enzyme method degumming step, a pre-decoloring step and a physical deacidification step.

Description

Technical Field

[0001] The present invention belongs to the field of oil processing, and particularly relates to a green, precise and moderate processing wheat germ oil with zero trans fatty acids and a preparation method thereof. Background Art

[0002] Wheat germ is a nutritional byproduct of the wheat flour industry. Wheat germ oil (hereinafter referred to as wheat germ oil) accounts for about 8-14% of the mass of wheat germ. It is rich in polyunsaturated fatty acids and is also the richest source of tocopherols and sterols. Therefore, wheat germ oil is widely praised for its medicinal and nutritional value. The oil extracted from wheat germ is often called crude wheat germ oil. In addition to mainly containing triglycerides (neutral oil) and diglycerides, the crude oil also contains a relatively high proportion of impurities, including but not limited to free fatty acids, phospholipids, pigments, various metal ions or other impurities. Therefore, in order to meet the requirements of oil production and consumers for high nutrition and good appearance of products, the crude oil needs to be refined. The refined oil obtained can be used for human consumption and absorption, providing the fatty acids and nutrients required by the human body. Generally, the refining methods of crude oil mainly include chemical refining method and physical refining method. The process of the chemical refining method generally includes degumming, caustic refining, decolorization and deodorization (acid removal) processes, among which acid removal is mainly completed in the caustic refining and deodorization sections; while the physical refining method does not add caustic solution and mainly extracts the free fatty acids in the crude oil by means of steam stripping, that is, acid removal is mainly completed in the physical acid removal and deodorization sections.

[0003] However, in most actual productions, in order to ensure the production of relatively high-quality refined oil, there are often problems of overly strict index control and prominent over-processing, and there are potential quality and safety hazards. For example, there are problems such as a large amount of alkali addition, high deodorization temperature, and long time. These problems not only cause waste of resources and energy, aggravate environmental pollution, and increase oil loss, but also result in the loss of most of the natural beneficial micronutrients in vegetable oil and inevitably generate new harmful substances.

[0004] Commercially available wheat germ oil products all have the problem of over-refining. The main reason is that the crude wheat germ oil has a higher phospholipid content, acid value, VE&sterol content and polyunsaturated fatty acid content than other common crude oils. In the refining process, in order to reduce the acid value and phosphorus content, it is very easy to cause a large loss of trace components or the generation of substances such as TFA (trans fatty acids). And TFA will increase the risk of coronary heart disease (CHD) and other diseases, and has attracted more and more attention in the whole industry in recent years and needs to be strictly controlled.

[0005] Therefore, in order to obtain high-quality wheat germ oil, it is urgent to solve the problems of high phospholipid content, high acid value of crude wheat germ oil compared with other common crude oils, and difficult retention rate of nutritional components in this field. At the same time, it is necessary to improve the retention rate of VE&sterol and control the generation of TFA. Summary of the Invention

[0006] The first aspect of the present invention provides a method for reducing the phosphorus content in wheat germ oil during the refining process, which method comprises an acid degumming step and an enzymatic degumming step; wherein, in the acid degumming, the amount of acid used is 2000-5000 mg of acid per kg of oil weight, preferably 3000-4600 mg of acid per kg of oil weight, more preferably 3200-4600 mg of acid per kg of oil weight.

[0007] In some embodiments, the acid degumming comprises: adding an acid solution to crude wheat germ oil, stirring, performing solid-liquid separation, and taking the oil phase; preferably, the acid degumming temperature is 40-90°C, preferably 50-70°C; preferably, the degumming time is 10-60 min, preferably 15-45 min; preferably, the acid is phosphoric acid and / or citric acid.

[0008] In some embodiments, the enzymatic degumming comprises: adding a degumming enzyme to the oil, reacting for a period of time under the conditions of 40-60°C and a pH of 4-6, and separating the gum after the reaction to obtain degummed oil; preferably, the reaction time is 2-8 h, preferably 4-6 h; preferably, the addition amount of the enzyme is 5-1000 mg of enzyme per kg of oil weight, preferably 10-100 mg of enzyme per kg of oil weight, more preferably 30-100 mg of enzyme or 50-100 mg of enzyme per kg of oil weight; preferably, a phospholipase, such as PLA1, is used for enzymatic degumming.

[0009] In some embodiments, acid degumming is first carried out, and then enzymatic degumming is carried out; preferably, after the acid degumming is completed, the pH of the system is adjusted without separating the gum, and then the degumming enzyme is added for enzymatic degumming; preferably, after adjusting the pH of the system obtained by acid degumming, the degumming enzyme is added for degumming.

[0010] In some embodiments, after degumming, the gum is separated; preferably, the gum is separated by centrifugation, then 1-5% of deionized water at 70-90°C based on the oil weight is added for water washing, after water washing, centrifugal dehydration is carried out, and then the residual water is removed in a vacuum tank under vacuum to obtain degummed oil.

[0011] In some embodiments, the method further comprises the steps of pre-bleaching and physical deacidification of the degummed oil.

[0012] In some embodiments, the pre-bleaching step is a step of adding a bleaching medium to the degummed oil for bleaching; preferably, the bleaching medium is selected from one or more of fuller's earth, activated clay, activated carbon, zeolite, attapulgite, diatomaceous earth, and silica gel; preferably, the dosage of the bleaching medium is 0.5-4.0% by weight of the oil, preferably 1.0-4.0% by weight of the oil; preferably, the bleaching temperature is 100-110 °C, preferably 105 ± 3 °C; preferably, the bleaching time is 20-40 minutes, preferably 30 ± 5 minutes; preferably, after the pre-bleaching is completed, the bleaching medium is removed to obtain pre-bleached oil.

[0013] In some embodiments, physical deacidification includes treating the pre-bleached oil at a pressure of 2-5 mbar and a temperature of 190-210 °C, preferably 200-210 °C, for a treatment time of 1.5-2.5 h, preferably 1.5-2.0 h.

[0014] In some embodiments, the method further includes an alkali refining step and an optional soapstock removal step; wherein, alkali refining is carried out after degumming, after pre-bleaching, or after physical deacidification.

[0015] In some embodiments, the alkali refining temperature is 70-90 °C, preferably 80-90 °C; the alkali refining reaction time is 10-80 minutes, such as 20-60 minutes; the alkali solution used for alkali refining is sodium hydroxide solution or potassium hydroxide solution; the concentration of the alkali solution is 5-15 wt%, preferably 5-10 wt%, more preferably 6-9%; the addition amount of the alkali solution is 0.5-15%, 1-10% by weight of the oil.

[0016] In some embodiments, soapstock removal is carried out by centrifugation or by adding a non-aqueous soapstock removal medium; preferably, the non-aqueous soapstock removal medium is selected from waste clay and diatomaceous earth; preferably, 0.1-5%, such as 0.5-3%, of the soapstock removal medium by weight of the alkali-refined and deacidified oil is added to the alkali-refined and deacidified oil, and soapstock removal is carried out at a pressure of 2-40 kPa, preferably 2-10 kPa, and a temperature of 80-120 °C, preferably 80-100 °C; preferably, after soapstock removal, the oil is washed and dried to obtain neutralized oil.

[0017] In some embodiments, the method further includes bleaching and / or deodorization; preferably, the bleaching and deodorization are carried out after alkali refining.

[0018] In some embodiments, the bleaching medium used for bleaching is selected from one or more of fuller's earth, activated clay, activated carbon, zeolite, attapulgite, diatomaceous earth, and silica gel; preferably, the dosage of the bleaching medium is 0.5-4.0% by weight of the oil, preferably 1.0-4.0% by weight of the oil; preferably, the bleaching temperature is 100-110 °C, preferably 105 ± 3 °C; preferably, the bleaching time is 20-40 minutes, preferably 30 ± 5 minutes; preferably, after bleaching is completed, the bleaching medium is removed to obtain bleached oil.

[0019] In some embodiments, deodorization is carried out at 1 to 4 mbar and 190 to 210 °C, and the deodorization time is 40 to 150 minutes, preferably 60 to 120 minutes.

[0020] The second aspect of the present invention provides a method for reducing the acid value and free fatty acid content of oil during the refining process of wheat germ oil, while enabling the retention rate of VE in the oil to be ≥90% and the retention rate of sterols to be ≥93%. This method sequentially includes the acid degumming, enzymatic degumming, pre-decolorization step, and physical deacidification step described in any one of the embodiments herein.

[0021] In some embodiments, the method further includes the caustic refining step described in any one of the embodiments herein.

[0022] In some embodiments, the method further includes the decolorization and / or deodorization step described in any one of the embodiments herein.

[0023] The third aspect of the present invention provides an oil prepared by the method described in any one of the embodiments herein.

[0024] The fourth aspect of the present invention provides a blended oil containing the oil described herein.

[0025] The fifth aspect of the present invention provides a food containing the oil or blended oil described herein.

[0026] The sixth aspect of the present invention provides the application of the combination of acid degumming, enzymatic degumming, and caustic refining in reducing the phosphorus content of wheat germ oil; or the application of physical deacidification, caustic refining, and deodorization in reducing the acid value of wheat germ oil to below 0.30 mg KOH / g, controlling TFA to ≤0.30%, while enabling the retention rate of VE in the wheat germ oil to be ≥90% and the retention rate of sterols to be ≥93%; preferably, the acid degumming, enzymatic degumming, caustic refining, physical deacidification, and deodorization are as described in any one of the embodiments herein.

[0027] Other aspects of the present invention will be apparent to those skilled in the art from the disclosure herein. Detailed Embodiments

[0028] Wheat germ oil (abbreviated as wheat germ oil) itself contains rich nutritional components, including vitamin E (VE) and sterols. However, during the refining process of wheat germ oil, the phospholipid content and acid value are higher than those of other common crude oils, while the retention rates of nutritional components such as VE and sterols are lower. At the same time, trans fatty acids (TFA) are also generated during the refining of wheat germ oil, further affecting the quality of wheat germ oil.

[0029] To solve the above problems, through in-depth research, the inventor of the present invention can reduce the phosphorus content of the finished wheat germ oil to less than 2 mg / kg by selecting appropriate degumming and alkali refining steps. Further, the inventor also found that by selecting appropriate physical deacidification, alkali refining deacidification, and deodorization deacidification processes, the acid value of the finished wheat germ oil can be reduced to less than 0.30 mg KOH / g, the TFA can be controlled to ≤0.30%, and the VE retention rate ≥90%, and the sterol retention rate ≥93%. Thus, the present invention is completed.

[0030] Therefore, the present invention provides a method for reducing the phosphorus content of oil during the refining process of wheat germ oil, which method comprises an acid degumming step and an enzymatic degumming step. Herein, the acid degumming comprises: adding an acid solution to crude wheat germ oil, stirring, performing solid-liquid separation, and taking the oil phase. The temperature for acid degumming can be 40 - 90 °C, preferably 50 - 70 °C. The degumming time can be 10 - 60 min, preferably 15 - 45 min. The acid can be an acid commonly used for acid degumming, such as phosphoric acid and / or citric acid. In some embodiments, the present invention uses citric acid for acid degumming. Herein, the dosage of an acid such as citric acid is: 2000 - 5000 mg of acid per kg of oil weight, preferably 3000 - 4600 mg of acid per kg of oil weight, more preferably 3200 - 4600 mg of acid per kg of oil weight. The acid can be formulated into an aqueous solution of a certain concentration, and this aqueous solution is mixed with the crude oil for degumming. The concentration of the solution can be 1 - 50 wt%, for example 10 - 30 wt%.

[0031] Herein, the enzymatic degumming can comprise: adding a degumming enzyme (such as phospholipase) to the oil, reacting for a period of time under certain temperature and pH conditions, and separating the gum after the reaction to obtain degummed oil. The temperature for enzymatic degumming can be 40 - 60 °C, preferably 50 - 60 °C; the pH can be 4 - 6, preferably 4.5 - 5.5; the reaction time can be 2 - 8 h, preferably 4 - 6 h; the addition amount of the enzyme can be 5 - 1000 mg of enzyme per kg of oil weight, preferably 10 - 100 mg of enzyme per kg of oil weight, more preferably 30 - 100 mg of enzyme or 50 - 100 mg of enzyme per kg of oil weight. The enzyme used for enzymatic degumming can be various phospholipases well-known in the art, such as PLA1. In an exemplary embodiment, phospholipase PLA1 from Novozymes can be used.

[0032] In this article, it is preferred to first perform acid degumming and then enzymatic degumming. After the acid degumming is completed, the gum can be not separated out, and the pH of the system can be directly adjusted and then degumming enzyme can be added to perform enzymatic degumming. An appropriate amount of base such as sodium hydroxide can be added to the system after the acid degumming reaction to adjust the pH value of the system to the appropriate working pH of the degumming enzyme. The amount of the added base can be determined according to the pH value in the system after enzymatic degumming. Exemplarily, the addition amount of the base used to adjust the pH can be 600 - 1400 mg of base per kilogram of oil weight, preferably 800 - 1200 mg of base per kilogram of oil weight, and more preferably 1000 - 1200 mg of base per kilogram of oil weight.

[0033] After the degumming is completed, the gum can be separated. For example, the gum can be separated by centrifugation, and then an appropriate amount of deionized water can be added for water washing. Generally, the temperature of the water used for water washing can be in the range of 70 - 90 °C, and the water consumption can be 1 - 5% of the oil weight. After water washing, it can be centrifuged for dehydration, and then the residual water can be removed in a vacuum tank to finally obtain degummed oil.

[0034] By using the degumming method described in this article, the phosphorus content of crude wheat germ oil can be reduced to below 50 ppm. In some embodiments, by using the degumming method described in this article, the phosphorus content of crude wheat germ oil can be reduced to below 40 ppm; in some embodiments, by using the degumming method described in this article, the phosphorus content of crude wheat germ oil can be reduced to below 35 ppm; in some embodiments, by using the degumming method described in this article, the phosphorus content of crude wheat germ oil can be reduced to below 30 ppm.

[0035] In some embodiments, the method for reducing the phosphorus content of oil described in this article further includes the steps of pre - decolorization and physical deacidification of the degummed oil.

[0036] In this article, the pre - decolorization step is the step of adding a decolorizing medium to the degummed oil for decolorization. The decolorizing medium can be a commonly used decolorizing medium in the art, including but not limited to bleaching earth, activated clay, activated carbon, zeolite, attapulgite, diatomaceous earth, and silica gel. One or more decolorizing media can be used for decolorization. Generally, the dosage of the decolorizing medium is 0.5 - 4.0% of the oil weight, preferably 1.0 - 4.0% of the oil weight. The decolorization temperature can be 100 - 110 °C, preferably 105 ± 3 °C. The decolorization time can be 20 - 40 minutes, preferably 30 ± 5 minutes. After the pre - decolorization is completed, the decolorizing medium can be filtered off to obtain pre - decolorized oil.

[0037] In this article, physical deacidification includes treating the pre - decolorized oil at a pressure of 2 - 5 mbar and a temperature of 190 - 210 °C, and the treatment time can be 1.5 - 2.5 h. In some embodiments, the temperature of physical deacidification is preferably 200 - 210 °C. In some embodiments, the time of physical deacidification can be 1.5 - 2.0 h.

[0038] In this text, the degummed oil obtained through pre - decolorization treatment and physical de - acidification treatment has its phosphorus content further reduced to below 20 ppm, preferably further reduced to below 15 ppm.

[0039] In some embodiments, the method for reducing the phosphorus content of oil and fat described herein further includes the step of caustic refining the degummed oil.

[0040] In this text, the process conditions for caustic refining can be those in "Bailey's Industrial Oil and Fat Products" (Volume VI), etc. Generally, the caustic refining temperature can be 70 - 90 °C, preferably 80 - 90 °C. The caustic refining reaction time can be 10 - 80 minutes, such as 20 - 60 minutes. The caustic solution is usually a sodium hydroxide solution. The concentration of the caustic solution such as sodium hydroxide solution can be 5 - 15 wt%, preferably 5 - 10 wt%, more preferably 6 - 9%. The addition amount of the caustic solution can be conventional in the art. For example, it can be 0.5 - 15%, 1 - 10% of the oil weight. Those skilled in the art can understand that the caustic added during caustic refining is divided into two parts: theoretical caustic and excess caustic. Generally, the amount of added caustic = 7.13×10 -4 ×M_oil×AV×(1 + excess caustic amount), the excess caustic amount can be 0 - 20%, the amount of caustic solution = the amount of added caustic / the concentration of the caustic solution, where M_oil refers to the weight of the oil and AV refers to the acid value. In some embodiments, the caustic refining step of the present invention includes: heating the degummed oil to 70 - 90 °C, preferably 80 - 90 °C, adding the caustic solution and reacting for 20 - 60 minutes, the concentration of the caustic solution is 5 - 10%, preferably 6 - 9%, and the excess caustic is 0 - 20%. After the reaction, centrifugation can be carried out first, and then degumming, water washing and drying are carried out to obtain neutralized oil.

[0041] Degumming of the degummed oil can be carried out by methods well - known in the art, such as degumming by centrifugation. In some embodiments, a non - aqueous degumming medium can also be added for degumming. The non - aqueous degumming medium can be various media conventionally used for anhydrous degumming in the art, including spent bleaching earth, diatomaceous earth, etc. An appropriate amount of degumming medium can be added to the caustic - refined degummed oil, such as 0.1 - 5%, such as 0.5 - 3% of the weight of the caustic - refined degummed oil, and degumming is carried out under a pressure of 2 - 40 kPa, preferably 2 - 10 kPa and a temperature of 80 - 120 °C, preferably 80 - 100 °C. The degumming time can be selected according to actual conditions, for example, it can be 10 - 180 minutes.

[0042] Water washing and drying of the degummed oil can be carried out by techniques well - known in the art. For example, the addition amount of water during water washing can be 1 - 5% of the oil weight, and the water temperature can be 70 - 90 °C. Drying can be carried out by the method described above.

[0043] After the caustic refining step, the phosphorus content of the neutralized oil obtained in this application is further reduced to below 3.0 ppm, preferably further reduced to below 2.5 ppm.

[0044] In some embodiments, the method for reducing the phosphorus content in oil and fat described herein further includes a step of decolorizing the neutralized oil. Herein, the decolorizing medium used in the decolorizing step can be a commonly used decolorizing medium in the art, including but not limited to bleaching earth, activated clay, activated carbon, zeolite, attapulgite, diatomaceous earth, and silica gel. One or more decolorizing media can be used for decolorization. Generally, the dosage of the decolorizing medium is 0.5 - 4.0% by weight of the oil, preferably 1.0 - 4.0% by weight of the oil. The decolorizing temperature can be 100 - 110 °C, preferably 105 ± 3 °C. The decolorizing time can be 20 - 40 minutes, preferably 30 ± 5 minutes. After the decolorization is completed, the decolorizing medium can be removed by filtration to obtain decolorized oil.

[0045] In some embodiments, the method for reducing the phosphorus content in oil and fat described herein further includes a step of deodorizing the decolorized oil. Herein, the deodorization can be carried out at 1 - 4 mbar and 190 - 210 °C, and the deodorizing time can be 40 - 150 minutes, preferably 60 - 120 minutes. The phosphorus content of the obtained deodorized (i.e., refined wheat germ oil) can be below 2.0 ppm, preferably below 1.5 ppm, more preferably below 1.0 ppm.

[0046] In some other embodiments, the present invention also provides a method for reducing the acid value and free fatty acid content of oil and fat during the refining process of wheat germ oil, while enabling the retention rate of VE in the oil and fat to be ≥ 90% and the retention rate of sterol to be ≥ 93%. This method sequentially includes the acid degumming and enzymatic degumming steps, pre - decolorizing step, and physical deacidification step described in any of the embodiments herein. In some embodiments, the AV of the deacidified oil obtained by using these steps is reduced to below 6.0 mg KOH / g, preferably below 4.5 mg KOH / g; TFA ≤ 0.20%, preferably ≤ 0.18%; the retention rates of both VE and sterol are ≥ 99%, preferably ≥ 99.5%.

[0047] Herein, the term "retention rate" refers to the ratio of the absolute amount of a certain nutrient component (such as VE or sterol) in the oil and fat to the absolute amount of the same nutrient component in the crude wheat germ oil or the oil and fat before implementing a certain process. The percentage of "loss" refers to the ratio of the absolute amount of the lost nutrient component (such as VE or sterol) to the absolute amount of the same nutrient component in the crude oil or the oil and fat before implementing a certain process.

[0048] In some embodiments, the method for reducing the acid value and free fatty acid content of the oil during the refining process of wheat germ oil, while the retention rate of VE in the oil is ≥90% and the retention rate of sterols is ≥93%, further includes subjecting the degummed oil to the caustic refining step described in any of the embodiments herein. In some embodiments, for the neutralized oil obtained by caustic refining, its AV value is below 0.5 mg KOH / g, preferably below 0.4 mg KOH / g; the retention rate of VE is ≥95.5%, preferably ≥96.5%, and the retention rate of sterols is ≥97%, preferably ≥98%.

[0049] In some embodiments, the method for reducing the acid value and free fatty acid content of the oil during the refining process of wheat germ oil, while the retention rate of VE in the oil is ≥90% and the retention rate of sterols is ≥93%, further includes subjecting the neutralized oil to the decolorization step described in any of the embodiments herein. In some embodiments, for the decolorized oil obtained by decolorization, its AV value is below 0.5 mg KOH / g, preferably below 0.4 mg KOH / g; the retention rate of VE is ≥94.5%, preferably ≥95.5%, and the retention rate of sterols is ≥96.0%, preferably ≥97.0%.

[0050] In some embodiments, the method for reducing the acid value and free fatty acid content of the oil during the refining process of wheat germ oil, while the retention rate of VE in the oil is ≥90% and the retention rate of sterols is ≥93%, further includes subjecting the neutralized oil to the deodorization step described in any of the embodiments herein. In some embodiments, for the refined wheat germ oil obtained by deodorization, the acid value ≤0.30 mg KOH / g, TFA ≤0.30%, the retention rate of VE ≥90%, and the retention rate of sterols ≥93%.

[0051] On the other hand, the present invention also provides a method for preparing green, precise and moderately processed wheat germ oil, which successively includes the steps of acid degumming, enzymatic degumming, pre-decolorization, physical deacidification, caustic refining, decolorization and deodorization described in any of the embodiments herein. By using this green, precise and moderately processed technology, the present invention prepares a zero-trans, green, precise and moderately processed wheat germ oil with a phosphorus content ≤2 mg / kg, trans fatty acid (TFA) ≤0.30%, a vitamin E retention rate of more than 90% and a sterol retention rate of more than 93% compared with the starting crude wheat germ oil.

[0052] In some embodiments, the present invention provides a degummed oil. Based on the total weight of the degummed oil, the content of trans fatty acid (TFA) in the degummed oil is ≤0.20%, preferably ≤0.18%; the phosphorus content is ≤20 mg / kg, preferably ≤15 mg / kg; compared with the oil before physical deacidification treatment, the vitamin E contained in the degummed oil is more than 99% of the vitamin E contained in the oil before treatment, preferably more than 99.5%; the sterols contained are more than 99% of the sterols contained in the oil before treatment, preferably more than 99.5%.

[0053] In one or more embodiments, the acid value (AV) of the degummed oil is 2.0 - 6.0 mg KOH / g, preferably 2.5 - 4.5 mg KOH / g.

[0054] In one or more embodiments, the degummed oil is prepared by the physical degumming treatment step described in any one of the embodiments herein.

[0055] The present invention provides a neutralized oil. Based on the total weight of the neutralized oil, the phosphorus content in the neutralized oil is ≤ 2.5 mg / kg; compared with the oil before caustic refining treatment, the vitamin E contained in the neutralized oil is more than 95.5%, preferably more than 96.5% of the vitamin E contained in the oil before treatment; the sterol content is more than 97%, preferably more than 98% of the sterol contained in the oil before treatment.

[0056] In one or more embodiments, the acid value (AV) of the neutralized oil is ≤ 0.5 mg KOH / g, preferably ≤ 0.4 mg KOH / g.

[0057] In one or more embodiments, the neutralized oil is prepared by the method for moderately degumming wheat germ oil described in any one of the embodiments herein.

[0058] The present invention provides a refined oil. Based on the total weight of the refined oil, the phosphorus content in the refined oil is ≤ 2 mg / kg; the trans fatty acid (TFA) is ≤ 0.30%. Compared with the starting wheat germ crude oil, the retention rate of vitamin E is more than 90%; the retention rate of sterol is more than 93%.

[0059] In one or more embodiments, the acid value (AV) of the refined oil is ≤ 0.30 mg KOH / g, preferably ≤ 0.20 mg KOH / g, for example ≤ 0.15 mg KOH / g.

[0060] In one or more embodiments, the refined oil is prepared by the processing method of wheat germ oil described in any one of the embodiments herein (preferably the method for green and precise moderate processing of wheat germ oil).

[0061] In one or more embodiments, the degummed oil, the neutralized oil, and the refined oil are all moderately processed oils.

[0062] The present invention also provides a wheat germ oil composition, which comprises the degummed oil of the wheat germ oil described in any one of the embodiments herein, and / or the neutralized oil of the wheat germ oil described in any one of the embodiments herein, and / or the refined oil of the wheat germ oil described in any one of the embodiments herein. The degummed oil of the wheat germ oil described in any one of the embodiments herein, and / or the neutralized oil of the wheat germ oil described in any one of the embodiments herein, and / or the refined oil of the wheat germ oil described in any one of the embodiments herein, and / or the wheat germ oil composition described in any one of the embodiments herein can be used to prepare a blended oil. To obtain desired properties, such as zero trans fatty acids (TFA≤0.30%), reduced phosphorus content in the oil (phosphorus content≤2mg / kg), reduced acid value (AV≤0.30mg KOH / g), and increased nutritional components in the oil (VE retention rate≥90%, and / or sterol retention rate≥93%), the content of the degummed oil, neutralized oil, refined oil of the wheat germ oil, and / or the wheat germ oil composition in the blended oil can be appropriately controlled, which can be determined by those skilled in the art using methods known in the art. Generally, based on 100% by weight of the blended oil, the blended oil contains at least 25%, at least 35%, at least 45%, preferably at least 55%, preferably at least 65%, preferably at least 70%, preferably at least 85%, preferably at least 90%, more preferably at least 95%, more preferably 100% of the degummed oil, neutralized oil, refined oil of the wheat germ oil, and / or the wheat germ oil composition. The blended oil of the present invention may also contain other oils other than the degummed oil, neutralized oil, refined oil of the wheat germ oil, and / or the wheat germ oil composition described herein, including but not limited to one or more of soybean oil, sunflower oil, rapeseed oil, rice bran oil, peanut oil, corn oil, sesame oil, and safflower oil. The method for preparing the blended oil is also known in the art. For example, each oil type used for preparing the blended oil can be sequentially added to a batching tank, the temperature is maintained at 20°C - 40°C, and slow stirring is carried out for 20 - 30 min, and then filtration and filling are carried out to obtain the finished blended oil herein.

[0063] The advantages of the present invention are as follows:

[0064] (1) Aiming at the problems that it is difficult to degum the crude wheat germ oil by conventional hydration and acid degumming methods, with poor effects and high phospholipid content, the present invention obtains a finished wheat germ oil with a phosphorus content of less than 2mg / kg through steps such as acid degumming and enzymatic degumming.

[0065] (2) Aiming at the problems of high acid value and difficulty in retaining trace components in the crude wheat germ oil, the present invention adopts moderate physical deacidification treatment, combined with subsequent mild caustic refining deacidification steps and moderate deodorization deacidification steps, and the acid value in the refined wheat germ oil obtained is lower than 0.30mg KOH / g, TFA≤0.30%, and the VE retention rate is ≥90%, and the sterol retention rate is ≥93%.

[0066] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The methods and reagents used in the embodiments are conventional methods and reagents in the art unless otherwise specified. Unless otherwise specified, the percentages refer to mass percentages.

[0067] Experimental materials:

[0068] Crude wheat germ oil: provided by Henan Kunhua Biotechnology Co., Ltd.

[0069] Crude soybean oil: provided by Kerry Food Industry Co., Ltd., Shanghai.

[0070] PLA1 enzyme: provided by Shanghai Aladdin Biochemical Technology Co., Ltd., manufacturer Novozymes, product number P299005.

[0071] Clay for decolorization: provided by Jiangxi Yile Zhongrun Bleaching Earth Technology Co., Ltd.

[0072] Alkali solution in the alkali refining process: sodium hydroxide, manufacturer Greagent, product number G19852, the concentration of the prepared alkali solution is 5-15%.

[0073] Detection methods:

[0074] Acid value (AV): detected with reference to GB5009.229 2016-2016 of the national standard.

[0075] Phosphorus content: detected with reference to GB / T 5537-2008 of the national standard.

[0076] Vitamin E (VE): determined with reference to AOCS Ce 8-89(2017) for the determination of tocopherols and tocotrienols in vegetable oils.

[0077] Sterols: detected with reference to GB / T 25223-2010 for the determination of sterol composition and total sterols in animal and vegetable oils by gas chromatography.

[0078] Trans fatty acids (TFA): determined with reference to GB5009.257—2016 for the determination of trans fatty acids in foods.

[0079] Examples and comparative examples

[0080] 1. Acid degumming and enzymatic degumming: Heat the raw wheat germ oil to 40 - 60 °C, add a 10 - 50 wt% citric acid solution, then perform high - speed shearing and react for 20 - 60 min. Next, add a sodium hydroxide solution, perform high - speed shearing and react for 10 - 60 min. Finally, add PLA1 phospholipase and deionized water, perform high - speed shearing and react for 4 - 6 h. After the reaction, centrifuge to separate the gum, then add deionized water for washing, and after centrifugal dehydration, put it into a vacuum tank to remove the residual water under vacuum to obtain degummed oil. The oil types, citric acid addition amounts, sodium hydroxide addition amounts, reaction times for acid degumming, enzyme addition amounts, reaction times for enzymatic degumming, pH values, and deionized water addition amounts in each example and comparative example are shown in Table 1 below.

[0081] Table 1: Combined acid and enzymatic degumming of examples and comparative examples

[0082]

[0083]

[0084] 2. Pre - decolorization and degumming: Pre - decolorize the degummed oil obtained in step 1 in a vacuum decolorization tank. The decolorization temperature, time, and dosage of the decolorizing medium (clay) are shown in Table 2 below. After pre - decolorization, filter to obtain pre - decolorized oil.

[0085] Table 2: Pre - decolorization of examples and comparative examples

[0086]

[0087]

[0088] 3. Moderate physical deacidification: Pump the pre - decolorized oil obtained in step 2 into a deacidification tower, and perform deacidification under the condition of 2 - 5 mbar according to the temperature and time of the deacidification tower shown in Table 3 to obtain deacidified oil.

[0089] Table 3: Moderate physical deacidification of examples and comparative examples

[0090]

[0091]

[0092] 4. Mild caustic refining deacidification: Perform caustic refining and centrifugally separate the soap from the physically deacidified oil obtained in step 3, add hot water for washing, and after centrifugal dehydration, put it into a vacuum tank to remove the residual water under vacuum to obtain neutralized oil. The process parameters of each step are shown in Table 4.

[0093] Table 4: Moderate caustic refining deacidification of examples and comparative examples

[0094]

[0095]

[0096] Comparative Example 16: First, caustic refining and deacidification were carried out according to the reaction conditions in Table 5, and then physical deacidification was carried out according to the reaction conditions in Table 6.

[0097] Table 5: Caustic refining and deacidification of Comparative Example 16

[0098]

[0099] Table 6: Physical deacidification of Comparative Example 16

[0100]

[0101] 5. Bleaching: The neutralized oil obtained in Step 4 was bleached in a vacuum bleaching tank. The bleaching temperature, time, and the amount of bleaching medium (clay) were as shown in Table 7 below. After bleaching, the bleached oil was obtained by filtration.

[0102] Table 7: Bleaching of Examples and Comparative Examples

[0103]

[0104]

[0105] 6. Moderate deodorization: The bleached oil obtained in Step 5 was pumped into a deodorization tower for deodorization. After deodorization, it was cooled to 30 - 45 °C and then finely filtered to obtain refined wheat germ oil. The deodorization temperature and time were as shown in Table 8. The deodorization pressure was 1 - 4 mbar.

[0106] Table 8: Moderate deodorization of Examples and Comparative Examples

[0107]

[0108]

[0109] The phosphorus content, VE change, sterol change, AV, and TFA generation of the examples and comparative examples were detected by the method described above. The results are shown in Tables 9 - 17 respectively.

[0110] Table 9: Phosphorus content of Examples and Comparative Examples

[0111]

[0112]

[0113] Note: — indicates that the experiment was not conducted.

[0114] Table 10: Phosphorus content of Comparative Example 16

[0115]

[0116] Note: — indicates that the experiment was not conducted.

[0117] Table 11: VE Changes in Examples and Comparative Examples

[0118]

[0119]

[0120] Note: — indicates that the experiment was not conducted.

[0121] Table 12: VE Changes in Comparative Example 16

[0122]

[0123] Note: — indicates that the experiment was not conducted.

[0124] Table 13: Sterol Changes in Examples and Comparative Examples

[0125]

[0126]

[0127] Note: — indicates that the experiment was not conducted.

[0128] Table 14: Sterol Changes in Comparative Example 16

[0129]

[0130] Note: — indicates that the experiment was not conducted.

[0131] Table 15: AV Values in Examples and Comparative Examples

[0132]

[0133]

[0134] Note: — indicates that the experiment was not conducted.

[0135] Table 16: AV Values in Comparative Example 16

[0136]

[0137]

[0138] Note: — indicates that the experiment was not conducted.

[0139] Table 17: TFA Generation in Examples and Comparative Examples

[0140]

[0141]

[0142] Note: — indicates that no experiment was conducted.

[0143] From the above experimental data results, it can be found that the refined wheat germ oil prepared by the methods of Examples 1-15 has high quality, that is, the phosphorus content is all lower than 2 mg / kg, the acid value is all lower than 0.30 mg KOH / g, TFA ≤ 0.30% (meeting the requirement of 0 trans in the national standard), and the VE retention rate ≥ 90%, and the sterol retention rate ≥ 93%.

[0144] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims. At the same time, all the documents mentioned in the present invention are cited as references in this application, just as each document is cited separately as a reference.

Claims

1. A method for reducing the phosphorus content in oil during the refining process of wheat germ oil, characterized in that, The method includes an acid degumming step and an enzymatic degumming step; wherein, in the acid degumming, the dosage of the acid is 2000 - 5000 mg of acid per kg of oil weight, preferably 3000 - 4600 mg of acid per kg of oil weight, more preferably 3200 - 4600 mg of acid per kg of oil weight.

2. The method according to claim 1, characterized in that: The acid degumming includes: adding an acid solution to crude wheat germ oil, stirring, performing solid-liquid separation, and taking the oil phase; preferably, the acid degumming temperature is 40 - 90 °C, preferably 50 - 70 °C; preferably, the degumming time is 10 - 60 min, preferably 15 - 45 min; preferably, the acid is phosphoric acid and / or citric acid; The enzymatic degumming includes: adding a degumming enzyme to the oil, reacting for a period of time under the conditions of 40 - 60 °C and pH 4 - 6, and separating the gum after the reaction to obtain degummed oil; preferably, the reaction time is 2 - 8 h, preferably 4 - 6 h; preferably, the enzyme addition amount is 5 - 1000 mg of enzyme per kg of oil weight, preferably 10 - 100 mg of enzyme per kg of oil weight, more preferably 30 - 100 mg of enzyme or 50 - 100 mg of enzyme per kg of oil weight; preferably, using a phospholipase, such as PLA1 for enzymatic degumming; Preferably, acid degumming is carried out first, and then enzymatic degumming; preferably, after the acid degumming is completed, without separating the gum, directly adjust the pH of the system and then add the degumming enzyme for enzymatic degumming; preferably, after adjusting the pH of the system obtained by acid degumming, add the degumming enzyme for degumming; Preferably, after degumming, separate the gum; preferably, separate the gum by centrifugation, then add 1 - 5% of the oil weight of deionized water at 70 - 90 °C for water washing, centrifugally dehydrate after water washing, and then enter a vacuum tank to vacuum remove the residual water to obtain degummed oil.

3. The method according to claim 1 or 2, characterized in that, The method further includes steps of pre-bleaching and physical deacidification of the degummed oil; Preferably, the pre-bleaching step is a step of adding a bleaching medium to the degummed oil for bleaching; preferably, the bleaching medium is selected from one or more of clay, activated clay, activated carbon, zeolite, attapulgite, diatomite, and silica gel; preferably, the dosage of the bleaching medium is 0.5 - 4.0% of the oil weight, preferably 1.0 - 4.0% of the oil weight; preferably, the bleaching temperature is 100 - 110 °C, preferably 105 ± 3 °C; preferably, the bleaching time is 20 - 40 minutes, preferably 30 ± 5 minutes; preferably, after pre-bleaching, remove the bleaching medium to obtain pre-bleached oil; Preferably, physical deacidification includes treating the pre-bleached oil at a pressure of 2 - 5 mbar and a temperature of 190 - 210 °C, preferably 200 - 210 °C, and the treatment time is 1.5 - 2.5 h, preferably 1.5 - 2.0 h.

4. The method according to any one of claims 1 to 3, characterized in that The method further includes an alkali refining step and an optional soapstock removal step; wherein, alkali refining is carried out after degumming, after pre-bleaching, or after physical deacidification; Preferably, the temperature for caustic refining is 70-90°C, preferably 80-90°C; the reaction time for caustic refining is 10-80 minutes, such as 20-60 minutes; the caustic solution used for caustic refining is sodium hydroxide solution or potassium hydroxide solution; the concentration of the caustic solution is 5-15 wt%, preferably 5-10 wt%, more preferably 6-9%; the addition amount of the caustic solution is 0.5-15%, 1-10% of the oil weight. Preferably, degumming is carried out by centrifugation or by adding a non-aqueous degumming medium; preferably, the non-aqueous degumming medium is selected from spent bleaching earth and diatomaceous earth; preferably, 0.1-5%, such as 0.5-3% of the degumming medium based on the weight of the caustic refined and deacidified oil is added to the caustic refined and deacidified oil, and degumming is carried out under a pressure of 2-40 kPa, preferably 2-10 kPa and a temperature of 80-120°C, preferably 80-100°C; preferably, after degumming, the oil is washed and dried to obtain neutralized oil.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes decolorization and / or deodorization; preferably, the decolorization and deodorization are carried out after caustic refining. Preferably, the decolorizing medium used for decolorization is selected from one or more of bleaching earth, activated bleaching earth, activated carbon, zeolite, attapulgite, diatomaceous earth and silica gel; preferably, the dosage of the decolorizing medium is 0.5-4.0% of the oil weight, preferably 1.0-4.0% of the oil weight; preferably, the decolorization temperature is 100-110°C, preferably 105±3°C; preferably, the decolorization time is 20-40 minutes, preferably 30±5 minutes; preferably, after decolorization, the decolorizing medium is removed to obtain decolorized oil. Preferably, deodorization is carried out at 1-4 mbar and 190-210°C, and the deodorization time is 40-150 minutes, preferably 60-120 minutes.

6. A method for reducing the acid value and free fatty acid content of oil during the refining of wheat germ oil, while making the VE retention rate of the oil ≥90% and the sterol retention rate ≥93%. The method sequentially includes the acid degumming and enzymatic degumming steps described in claim 1 or 2, the pre-decolorization step described in claim 3, and the physical deacidification step described in claim 4. Preferably, the method further includes the caustic refining step described in claim 4. Preferably, the method further includes the decolorization and / or deodorization step described in claim 5.

7. Oil prepared by using the method described in any one of claims 1-6.

8. A blended oil containing the oil described in claim 7.

9. A food containing the oil described in claim 7 or the blended oil described in claim 8.

10. The application of the combination of acid degumming, enzymatic degumming and caustic refining in reducing the phosphorus content of wheat germ oil; or the application of physical deacidification, caustic refining and deodorization in reducing the acid value of wheat germ oil to below 0.30 mg KOH / g, controlling TFA to ≤0.30%, while making the VE retention rate of the wheat germ oil ≥90% and the sterol retention rate ≥93%; preferably, the acid degumming and enzymatic degumming are as described in claim 1 or 2, and the caustic refining is as described in claim 4; preferably, the physical deacidification is as described in claim 3, and the deodorization is as described in claim 5.

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