Technological method for assisting precipitation refining of strong-flavor vegetable oil by utilizing plasma treatment

Abstract

The process method comprises the following steps: firstly, placing crude oil in a settling tank, naturally settling for 1-2 days, moving out the part from the upper layer to 2 / 3-5 / 6 of the bottom layer of an oil interface, and recording the moved part as to-be-treated oil S1; adding a proper amount of water into the to-be-treated grease S1, and stirring for 15-45 minutes at the rotating speed of 10-30 revolutions per minute to obtain to-be-treated grease S2; performing low-temperature plasma treatment on the to-be-treated grease S2 for 1-15 minutes under the condition that the output power is 40-80 W to obtain treated grease S3; the grease S3 is placed in a settling tank and naturally settled for 1-3 d, the part from the upper layer to 2 / 3-9 / 10 of the bottom layer of the oil interface is moved out, and the moved-out part is the strong-flavor vegetable oil finished product. According to the method, the precipitation refining time of the strong-flavor vegetable oil is greatly shortened, the efficiency is improved, the loss of flavor substances in the refining process of the strong-flavor vegetable oil is reduced, and the good flavor of the strong-flavor vegetable oil is kept.

Description

Technical Field

[0001] The invention relates to the field of vegetable oil processing, and in particular to a method for using plasma treatment to assist in the refining of rich-flavor oils. Background Art

[0002] Strong-flavored vegetable oil refers to the vegetable oil with strong aroma obtained by high-temperature roasting and pressing of oilseeds (rapeseed, peanuts, sesame, etc.). The crude oil of strong-flavored vegetable oil obtained by pressing contains colloidal impurities such as phospholipids, proteins, and sugars. It can only meet the edible oil standards after refining (degumming). The refining of strong-flavored vegetable oil must remove the colloidal impurities in the oil while ensuring that the flavor of the oil is retained to the greatest extent. The currently commonly used refining method of strong-flavored vegetable oil is mainly the natural sedimentation method. The main steps of the natural sedimentation method are: 1. Add about 1% of water to the crude oil (the amount of water added to different vegetable oils is different); 2. Stir; 3. Natural sedimentation (about 15 days). The entire natural sedimentation process can be divided into two stages: 1. Within the first 1-2 days of sedimentation, the large particles of colloid in the oil quickly form aggregates and settle; 2. After the large particles of colloid are settled, the small particles of colloid in the oil form an electrostatic balance, which requires a long time of sedimentation to be removed. If the electrostatic balance of small particles of colloid can be broken during the second stage of sedimentation, the time of the entire natural sedimentation can be greatly shortened. Based on this principle, some new degumming methods have been developed, such as adding citric acid, sodium chloride and other substances that can break the electrostatic balance to the oil to accelerate the sedimentation process. However, the addition of citric acid will cause a large loss of the flavor of the rich-flavored vegetable oil; the addition of sodium chloride will cause salt ions to remain in the oil, causing an increase in 3-chloropropanol ester (a harmful substance in oil). In addition, a Chinese patent document with publication number CN117106521B discloses a refining process for graded naturally precipitated sesame oil, comprising the following steps: Step (1): placing the crude sesame oil in a sedimentation tank with a height / diameter (tank height / tank diameter) ratio of 2:1 to 4:1, at a temperature between 4°C and 35°C, and naturally precipitating for 10-24 hours; Step 2: removing 2 / 3-4 / 5 of the sesame oil from the upper layer to the bottom layer of the sesame oil interface in step (1), the removed part is recorded as S1, and the bottom sedimentation layer is recorded as The S2 part; Step 3: Place the S1 part in a precipitation tank with a height / diameter (tank height / tank diameter) ratio of 2:1 to 4:1, add 0.1-1% of the weight of the sesame oil, stir at a speed of 5-20 rpm for 30 minutes and then stop stirring, then, at a temperature between 4°C and 35°C, naturally precipitate for 3-6 days, remove the sesame oil interface from the upper layer to the bottom layer 2 / 3-9 / 10 above, remove the part to obtain the sesame oil product, record it as the best grade finished sesame oil, and the bottom precipitate is recorded as the S3 part. This method shortens the oil refining time to 6-7 days by graded sedimentation, but it has a longer refining time compared with the method of adding citric acid or sodium chloride (refining time is about 2-4 days). At present, there is an urgent need for a method for refining rich-flavored vegetable oil that can simultaneously achieve simple, efficient and rapid removal of colloids in oils and fats, stably and efficiently retain the rich flavor of oils and fats, and does not introduce new harmful substances.

[0003] Cold plasma (CP) is a method of producing low-temperature, partially ionized gas rich in active oxygen and active nitrogen species by introducing electrical energy into the gas at atmospheric pressure and ambient temperature. The active substances produced by low-temperature plasma treatment can break the electrostatic balance in oils and fats, speed up the refining of oils and fats, and low-temperature plasma treatment is green, environmentally friendly and free of chemical residues. Therefore, combining low-temperature plasma treatment with the refining of aromatic vegetable oils can achieve good results. Summary of the invention

[0004] The present invention aims to solve the technical problems existing in the existing refining method of strong-flavor vegetable oil, and provides a process method for precipitation refining of strong-flavor vegetable oil assisted by plasma treatment, which can simply, quickly and effectively remove the colloid in the strong-flavor vegetable oil and maintain the flavor of the oil to the greatest extent.

[0005] The present invention provides a process for precipitation and refining of fragrant vegetable oil by using plasma treatment, comprising the following steps: Step (1): placing the crude oil in a sedimentation tank and allowing it to settle naturally for 1-2 days, removing the portion from the upper layer of the oil interface to 2 / 3-5 / 6 of the bottom layer, and recording the removed portion as the oil to be treated S1; Step (2): adding an appropriate amount of water to the oil to be treated S1, stirring at a speed of 10-30 rpm for 15-45 minutes to obtain the oil to be treated S2; Step (3): treating the oil S2 to be treated with low-temperature plasma at an output power of 40-80 W for 1-15 min to obtain treated oil S3; Step (4): Place the oil S3 in a sedimentation tank and allow it to settle naturally for 2 days, and remove the portion from the upper layer of the oil interface to more than 2 / 3-9 / 10 of the bottom layer. The removed portion is the finished product of the rich-flavor vegetable oil.

[0006] Furthermore, in the step 1, the crude oil is any kind of fragrant vegetable oil to be degummed. The crude oil is the oil product after the raw material is squeezed and deslagging.

[0007] Furthermore, in step 1 and step 3, the height / diameter ratio of the sedimentation tank (tank height / tank diameter) is 2:1 to 4:1, and the natural sedimentation temperature is between 4°C and 35°C.

[0008] Furthermore, in step 2, the amount of water added is 0.01-2%, which is adjusted according to the type of vegetable oil.

[0009] The beneficial technical effects of the present invention are embodied in the following aspects: (1) The degumming speed is fast, which improves the refining efficiency of vegetable oil and greatly shortens the refining time of rich-flavor vegetable oil.

[0010] (2) The entire refining time is short and there is no high temperature, which can preserve the rich flavor of the oil to the greatest extent.

[0011] (3) Low-temperature plasma treatment is natural, green, and residue-free, and will not introduce new harmful substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The following are the flavor substance detection results of the comparative example and the embodiment. DETAILED DESCRIPTION

[0013] 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.

[0014] The crude oil to be refined can be obtained by conventional methods, for example, roasting or frying sesame seeds until the sesame seeds are brown; pressing the roasted sesame seeds to obtain pressed cakes and crude oil (crude oil) containing residues, wherein the moisture content of the sesame seeds before pressing is 1.5-2.5%. In the following examples and comparative examples, the detection methods and conditions are as follows: (1) Determination of phospholipids The determination of phospholipid content in oils and fats is carried out in accordance with the provisions of GB / T 5537-2008. Lecithin is the main component of colloid in oils and fats. The lower its content, the better the degumming effect of the oils and fats.

[0015] (2) Determination of aroma components of oils and fats Solvent-assisted flavor evaporation (SAFE) was used to extract the volatile components of oil. Weigh 25 g of sesame oil, add 100 mL of dichloromethane, and add 150 μL of 4-nonanol (1 mg / mL) as an internal standard, and shake it on a shaker at 25°C for 10 h. The sample was placed in the dropping funnel of the SAFE device, and the temperature of the water bath and the circulating water bath were set to 50°C. Liquid nitrogen was added to the cold trap. When the vacuum degree of the system reached 3×10-3 MPa, the stopcock of the dropping funnel was slowly opened for extraction. The obtained extract was added with anhydrous Na2SO4 and placed in a refrigerator (-20°C) to dry overnight. The clear extract was filtered and concentrated to 5 mL by a Weiss concentrator column, and then nitrogen was blown to 3 mL. It was filtered through an organic filter membrane (0.22 μm) and analyzed using a gas chromatograph-mass spectrometer (7890B / 5977B) from Agilent, USA.

[0016] The instrument parameters of the gas chromatography-mass spectrometer were as follows: Volatile compounds were separated in a nonpolar HP-5MS capillary column (30 m long × 0.25 mm inner diameter × 0.25 μm thick). The column temperature was initially set to 40 °C for 5 min, increased to 230 °C at 3 °C / min, held for 5 min, and increased to 250 °C at 10 °C / min, held for 5 min. The compounds were analyzed by mass spectrometry in full-scan electron bombardment mode (70 ev) with a scan rate of 2.0 scan / s and a scan range of 33-400 m / z. The temperatures of the gas chromatograph inlet, quadrupole, ion source, and sniffing port were set to 250, 150, 230, and 280 °C, respectively.

[0017] Example 1 The present invention provides a process for precipitation and refining of rich-flavor vegetable oil by using low-temperature plasma treatment, comprising the following steps: Step (1): 2000 g crude oil is placed in a sedimentation tank and allowed to settle naturally for 1 day, and more than 4 / 5 of the portion from the upper layer to the bottom layer of the oil interface is removed, and the removed portion is recorded as the oil to be treated S1; Step (2): adding 1.6 g of water to the oil to be treated S1, and stirring at a speed of 10 rpm for 30 minutes to obtain the oil to be treated S2; Step (3): treating the oil S2 to be treated with low-temperature plasma at an output power of 40 W for 5 min (HPD-280, Nanjing Suman Plasma Technology Co., Ltd.) to obtain treated oil S3; Step (4): Place the oil S3 in a sedimentation tank and allow it to settle naturally for 2 days, and remove more than 4 / 5 of the oil from the upper layer to the bottom layer of the oil interface. The removed portion is the finished product of the rich-flavor vegetable oil.

[0018] In this embodiment, the phospholipid content of the obtained rich-flavor vegetable oil product is 0.045 mg / g, and the aroma concentration of the crude oil is 100 points, and the aroma concentration of the finished oil is scored as 90 points. The total refining time is 3 days, which is 11-13 days shorter than the traditional natural precipitation method.

[0019] Example 2 The present invention provides a process for precipitation and refining of rich-flavor vegetable oil by using low-temperature plasma treatment, comprising the following steps: The present invention provides a process for precipitation and refining of rich-flavor vegetable oil by using low-temperature plasma treatment, comprising the following steps: Step (1): 3000 g of crude oil is placed in a sedimentation tank and allowed to settle naturally for 1 day, and more than 4 / 5 of the portion from the upper layer to the bottom layer of the oil interface is removed, and the removed portion is recorded as the oil to be treated S1; Step (2): adding 2.4 g of water to the oil to be treated S1, and stirring at a speed of 30 rpm for 30 minutes to obtain the oil to be treated S2; Step (3): treating the oil S2 to be treated with low-temperature plasma at an output power of 80 W for 5 min (HPD-280, Nanjing Suman Plasma Technology Co., Ltd.) to obtain treated oil S3; Step (4): Place the oil S3 in a sedimentation tank and allow it to settle naturally for 2 days, and remove more than 2 / 3 of the oil interface from the upper layer to the bottom layer. The removed portion is the finished product of the rich-flavor vegetable oil.

[0020] In this embodiment, the phospholipid content of the obtained rich-flavor vegetable oil product is 0.044 mg / g, and the aroma concentration of the crude oil is 100 points, and the aroma concentration of the finished oil is scored as 90 points. The total refining time is 3 days, which is 11-13 days shorter than the traditional natural precipitation method.

[0021] Example 3 The present invention provides a process for precipitation and refining of rich-flavor vegetable oil by using low-temperature plasma treatment, comprising the following steps: Step (1): 2000 g crude oil is placed in a sedimentation tank and allowed to settle naturally for 2 days, and more than 4 / 5 of the oil from the upper layer to the bottom layer of the oil interface is removed, and the removed portion is recorded as the oil to be treated S1; Step (2): adding 1.6 g of water to the oil to be treated S1, and stirring at a speed of 20 rpm for 30 minutes to obtain the oil to be treated S2; Step (3): treating the oil S2 to be treated by low-temperature plasma at an output power of 40 W for 10 min (HPD-280, Nanjing Suman Plasma Technology Co., Ltd.), to obtain treated oil S3; Step (4): Place the oil S3 in a sedimentation tank and allow it to settle naturally for 2 days, and remove more than 4 / 5 of the oil from the upper layer to the bottom layer of the oil interface. The removed portion is the finished product of the rich-flavor vegetable oil.

[0022] In this embodiment, the phospholipid content of the obtained rich-flavor vegetable oil product is 0.039 mg / g, and the aroma concentration of the finished oil is scored as 89 points based on the aroma concentration of the crude oil as 100 points. The total refining time is 4 days, which is 11-13 days shorter than the traditional natural precipitation method.

[0023] Example 4 The present invention provides a process for precipitation and refining of rich-flavor vegetable oil by using low-temperature plasma treatment, comprising the following steps: Step (1): 2000 g crude oil is placed in a sedimentation tank and allowed to settle naturally for 1 day, and more than 4 / 5 of the portion from the upper layer to the bottom layer of the oil interface is removed, and the removed portion is recorded as the oil to be treated S1; Step (2): add 1.6 g of water to the oil to be treated S1, and stir at a speed of 30 rpm for 30 minutes to obtain the oil to be treated S2; Step (3): treating the oil S2 to be treated by low-temperature plasma at an output power of 40 W for 15 min (HPD-280, Nanjing Suman Plasma Technology Co., Ltd.) to obtain treated oil S3; Step (4): Place the oil S3 in a sedimentation tank and allow it to settle naturally for 2 days, and remove more than 4 / 5 of the oil from the upper layer to the bottom layer of the oil interface. The removed portion is the finished product of the rich-flavor vegetable oil.

[0024] In this embodiment, the phospholipid content of the obtained rich-flavor vegetable oil product is 0.04 mg / g, and the aroma concentration of the crude oil is 100 points, and the aroma concentration of the finished oil is scored as 90 points. The total refining time is 3 days, which is 11-13 days shorter than the traditional natural precipitation method.

[0025] Example 5 The present invention provides a process for precipitation and refining of rich-flavor vegetable oil by using low-temperature plasma treatment, comprising the following steps: Step (1): 2000 g crude oil is placed in a sedimentation tank and allowed to settle naturally for 1 day, and more than 4 / 5 of the portion from the upper layer to the bottom layer of the oil interface is removed, and the removed portion is recorded as the oil to be treated S1; Step (2): adding 1.6 g of water to the oil to be treated S1, and stirring at a speed of 30 rpm for 35 minutes to obtain the oil to be treated S2; Step (3): treating the oil S2 to be treated by low-temperature plasma at an output power of 80 W for 3 min (HPD-280, Nanjing Suman Plasma Technology Co., Ltd.) to obtain treated oil S3; Step (4): Place the oil S3 in a sedimentation tank and allow it to settle naturally for 2 days, and remove more than 4 / 5 of the oil from the upper layer to the bottom layer of the oil interface. The removed portion is the finished product of the rich-flavor vegetable oil.

[0026] In this embodiment, the phospholipid content of the obtained rich-flavor vegetable oil product is 0.048 mg / g, and the aroma concentration of the finished oil is scored as 88 points based on the aroma concentration of the crude oil as 100 points. The total refining time is 3 days, which is 11-13 days shorter than the traditional natural precipitation method.

[0027] Example 6 The present invention provides a process for precipitation and refining of rich-flavor vegetable oil by using low-temperature plasma treatment, comprising the following steps: Step (1): 2000 g crude oil is placed in a sedimentation tank and allowed to settle naturally for 2 days, and more than 2 / 3 of the portion from the upper layer to the bottom layer of the oil interface is removed, and the removed portion is recorded as the oil to be treated S1; Step (2): add 1.6 g of water to the oil to be treated S1, and stir at a speed of 25 rpm for 20 minutes to obtain the oil to be treated S2; Step (3): treating the oil S2 to be treated by low-temperature plasma at an output power of 70 W for 8 min (HPD-280, Nanjing Suman Plasma Technology Co., Ltd.) to obtain treated oil S3; Step (4): Place the oil S3 in a sedimentation tank and allow it to settle naturally for 2 days, and remove more than 4 / 5 of the oil from the upper layer to the bottom layer of the oil interface. The removed portion is the finished product of the rich-flavor vegetable oil.

[0028] In this embodiment, the phospholipid content of the obtained rich-flavor vegetable oil product is 0.04 mg / g, and the aroma concentration of the crude oil is 100 points, and the aroma concentration of the finished oil is scored as 90 points. The total refining time is 4 days, which is 11-13 days shorter than the traditional natural precipitation method.

[0029] Comparative Example 1 The traditional natural sedimentation method is used for refining without using low-temperature plasma assistance.

[0030] Step 1: Mix 3000 g of crude sesame oil with 3 g of water and stir at 20 r / min for 30 min to obtain the oil to be treated S1. Step 2: Add oil S1 into a sedimentation tank (height / diameter ratio is 4:1), settle naturally for 3 days, and remove more than 4 / 5 of the oil interface from the upper layer to the bottom layer. The removed part is the finished product of strong-flavor vegetable oil.

[0031] In this comparative example, the phospholipid content of the obtained Luzhou-flavor vegetable oil product is 0.63 mg / g; with the crude oil aroma concentration as 100 points, the aroma concentration of the finished oil is scored as 90 points. The results of determining the flavor substance content by gas chromatography-mass spectrometry show that compared with comparative example 1, the flavor substance content in Examples 1 to 6 is close to that in comparative example 1; while the phospholipid content in Examples 1 to 6 (0.045, 0.044, 0.039, 0.04, 0.048, 0.04 mg / g) is much lower than that in comparative example 1, which indicates that low-temperature plasma-assisted refining of Luzhou-flavor vegetable oil can effectively remove the colloid in the oil without losing the flavor substances.

[0032] Comparative Example 2 The traditional natural sedimentation method is used for refining without using low-temperature plasma assistance.

[0033] Step 1: Mix 3000 g of crude sesame oil with 3 g of water and stir at 20 r / min for 30 min to obtain the oil to be treated S1. Step 2: Add oil S1 into a sedimentation tank (height / diameter ratio is 4:1), settle naturally for 15 days, and remove more than 4 / 5 of the oil interface from the upper layer to the bottom layer. The removed part is the finished product of strong-flavor vegetable oil.

[0034] In this comparative example, the phospholipid content of the obtained finished product of the strong-flavored vegetable oil is 0.052 mg / g, and the aroma concentration of the crude oil is 100 points. The result of measuring the flavor substance content by gas chromatography-mass spectrometry shows that compared with comparative example 2, the flavor substance content in Examples 1 to 6 is higher than that in comparative example 2, and has a higher aroma concentration score; the phospholipid content in Examples 1 to 6 is similar to that in comparative example 2, which shows that the process method of using low-temperature plasma treatment to assist the precipitation and refining of the strong-flavored vegetable oil can achieve a degumming effect similar to that of natural sedimentation for 15 days, and can better maintain the flavor of the strong-flavored vegetable oil.

Claims

1. A process for precipitation and refining of aromatic vegetable oil using plasma treatment, characterized in that: The following steps are involved: Step (1): placing the crude oil in a sedimentation tank and allowing it to settle naturally for 1-2 days, removing the portion from the upper layer of the oil interface to 2 / 3-5 / 6 of the bottom layer, and recording the removed portion as the oil to be treated S1; Step (2): adding 0.01-2% water to the oil to be treated S1, stirring at a speed of 10-30 rpm for 15-45 minutes to obtain the oil to be treated S2; Step (3): treating the oil S2 to be treated with low-temperature plasma at an output power of 40-80 W for 1-15 min to obtain treated oil S3; Step (4): Place the oil S3 in a sedimentation tank and allow it to settle naturally for 1-3 days, and remove the portion from the upper layer of the oil interface to more than 2 / 3-9 / 10 of the bottom layer, and the removed portion is the finished product of the rich-flavor vegetable oil.

2. The process for precipitation and refining of Luzhou-flavor vegetable oil using plasma treatment as aid according to claim 1, characterized in that: The crude oil is the oil product obtained by pressing and removing the residue from the raw materials.

3. The process for precipitation and refining of Luzhou-flavor vegetable oil using plasma treatment as aid according to claim 1, characterized in that: The height / diameter ratio of the sedimentation tank is between 2:1 and 4:1, and the temperature of natural sedimentation is between 4°C and 35°C.

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