METHOD FOR REDUCING MINERAL OIL CONTENT IN EDIBLE VEGETABLE OIL

Abstract

A method for reducing mineral oil content in edible vegetable oil includes the following steps carrying out the molecular distillation on the edible vegetable oil having mineral oil exceedance; mixing water, the vegetable oil and an emulsifier with stirring to form an unstable emulsion; standing the emulsion for 1 to 5 hours for layer separation to form oil phase and emulsified phase, or oil phase, emulsified phase and water phase, and then separating different phases; freezing the oil phase after stirring, and then treating the oil phase with high-voltage pulsed electric field followed by ultrafiltration to obtain a vegetable oil I; subjecting the emulsion phase to low-temperature plasma treatment and then to high-voltage pulsed electric field treatment to break emulsion, drawing the upper oil phase for ultrafiltration followed by molecular distillation to obtain a vegetable oil II.

Claims

1. A method for reducing mineral oil content in edible vegetable oil, comprising the following steps of: S1. molecular distillation: carrying out molecular distillation on the edible vegetable oil having mineral oil exceedance; S2. emulsification: mixing water, the vegetable oil and an emulsifier with stirring to form an unstable emulsion; S3. standing the emulsion for layer separation to form oil phase and emulsified phase, or oil phase, emulsified phase and water phase, and then separating the different phases and retaining the oil phase and the emulsified phase for further treatment; S4. freezing the oil phase after stirring at a certain temperature, and then treating the oil phase with a high-voltage pulsed electric field, followed by ultrafiltration to obtain a vegetable oil I; and S5. subjecting the emulsified phase to low-temperature plasma treatment and then to high-voltage pulsed electric field treatment to break emulsion, drawing an upper oil phase for ultrafiltration, followed by molecular distillation to obtain a vegetable oil II; wherein the obtained vegetable oil I and vegetable oil II are both edible vegetable oil that have been reduced mineral oil content; wherein the mineral oil is mineral oil saturated hydrocarbon and/or mineral oil aromatic hydrocarbon.

2. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S1, the edible vegetable oil comprises, but is not limited to, perilla oil, evening primrose oil, borage oil, flaxseed oil, pumpkinseed oil, blackcurrant oil, hemp seed oil, grapeseed oil, wheat germ oil, avocado oil, safflower oil, olive oil, high oleic acid sunflower seed oil, sunflower seed oil, pecan oil, walnut oil, soybean oil, and sesame oil.

3. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S1, an evaporation pressure is 2 to 5 KPa, a distillation temperature is 115 to 155° C., a feeding speed is 25 to 40 drops/min, and a wiped film rotational speed is 150 to 180 rpm/min.

4. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S2, the water, vegetable oil and emulsifier are stirred at 40 to 70° C. for 25 to 75 minutes.

5. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S2, a volume ratio of the vegetable oil to the water is 1:2 to 5, and a content of the emulsifier is 0.5 to 3.5 wt. % of a system composed of the water, vegetable oil and emulsifier.

6. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S2, the emulsifier comprises one of non-ionic surfactants with HLB of 10 to 15, and a compound emulsifier with HLB of 10 to 15 formed by mixing several emulsifiers with different HLB in a certain proportion.

7. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S3, a standing time is 1 to 5 hours.

8. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S4, the oil phase is stirred at 40 to 80° C. for 0 to 50 minutes, and then is frozen at 0 to 4° C. for 0 to 2 hours, followed by treating the oil phase with the high-voltage pulsed electric field.

9. The method for reducing mineral oil content in edible vegetable oil according to claim 8, wherein in step S4, the conditions of the high-voltage pulsed electric field treatment are as follows: an intensity of the high-voltage pulsed electric field of 40 to 80 kV/cm, a pulse width of 5 to 20 μs, and a number of pulses of 50 to 150.

10. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S5, the conditions of the low-temperature plasma treatment are as follows: pulse discharge, a pulse voltage peak of 30 to 80 kV, a discharge frequency of 50 to 100 HZ and a treatment time of 5 to 30 minutes, and the treatment is repeated for 2 to 5 times.

11. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S5, the conditions of the high-voltage pulsed electric field treatment are as follows: an intensity of the high-voltage pulsed electric field of 30 to 80 kV/cm, a pulse width of 5 to 20 μs, and a number of pulses of 50 to 150.

12. The method for reducing mineral oil content in edible vegetable oil according to claim 1, wherein in step S5, the conditions of the molecular distillation are as follows: a evaporation pressure of 2 to 6 kPa, a distillation temperature of 120 to 160° C., a feeding speed of 20 to 40 drops/min, and a wiped film rotational speed of 150 to 190 rpm/min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0028] The following non-limiting embodiments can enable those skilled in the art to understand the present disclosure more comprehensively, but do not limit the present disclosure in any way.

Embodiment 1

[0029] S1. Perilla oil having mineral oil exceedance was subjected to molecular distillation, and the source of pollution was liquid paraffin with HLB 10.2. The evaporation pressure was 4 kPa, the distillation temperature was 140° C., the feeding speed was 35 drops/min, and the wiped film rotational speed was 160 rpm/min. [0030] S2. The perilla oil (HLB 7.4) obtained after treatment in step S1 was mixed with water and Tween 65 (HLB 10.5) with stirring at 50° C. for 50 min. An emulsion was obtained. The volume ratio of the perilla oil to the water was 1:3, and the content of Tween 65 was 1.5 wt. % of the whole system. [0031] S3. The emulsion obtained in step S2 was stood for 2 hours for layer separation to form an oil phase and an emulsified phase. The two phases were separated and respectively retained for further treatment. [0032] S4. The oil phase was stirred at 70° C. for 35 minutes, and then was frozen at 4° C. for 1 hour. The oil phase was then treated with high-voltage pulsed electric field. The intensity of the high-voltage pulsed electric filed was 60 kV/cm, the pulse width was 5 μs, and the number of pulses was 100. The oil phase was then subjected to ultrafiltration to obtain a perilla oil I. [0033] S5. The emulsified phase was subjected to low-temperature plasma treatment, and then was treated with high-voltage pulsed electric field to break emulsion. The upper oil phase was drawn for molecular distillation to obtain a perilla seed oil II. The discharge mode of the low-temperature plasma was pulse discharge, the pulse voltage peak was 40 kV, the discharge frequency was 60 HZ, the treatment time was 20 minutes, and the treatment was repeated for twice. The conditions of the high-voltage pulsed electric field treatment were as follows: the intensity of high-voltage pulsed electric field of 50 kV/cm, the pulse width of 10 μs, and the number of pulses of 50. The conditions of the molecular distillation were as follows: the evaporation pressure of 4 kPa, the distillation temperature of 150° C., the feeding speed of 30 drops/min, and the wiped film rotational speed of 160 rpm/min.

TABLE-US-00001 TABLE 1-1 Comparison of mineral oil contents in perilla oil I, perilla oil II and initial perilla oil Mineral Initial oil Standard perilla oil Perilla oil I Perilla oil II MOSH ≤10 ppm 91 ppm 6 ppm 9 ppm MOAH  ≤2 ppm 39 ppm Not detected (<1 ppm) 2 ppm

TABLE-US-00002 TABLE 1-2 Comparison of contents of other pollutants in perilla oil I, perilla oil II and initial perilla oil Initial Perilla Perilla Other pollutants Standard perilla oil oil I oil II Polycyclic aromatic  ≤10 ppb Not detected Not detected  3.6 ppb hydrocarbon (<0.5 ppb) (<0.5 ppb) (PAH 4) Trans-fatty acids ≤2% 0.19% 0.21% 0.71% Glycidyl ester ≤1000 ppb Not detected 105 ppb 195 ppb (<100 ppb) 3-MPCD ≤2500 ppb Not detected Not detected 280 ppb (<100 ppb) (<100 ppb)

[0034] It can be seen from Table 1-1 that MOSH and MOAH in the perilla oil I and perilla oil II obtained after treatment are reduced below the set standard. It can be seen from Table 1-2 that, at the strict condition control of this process, other pollutants all meet the requirements of European Union regulations on relevant pollutant limits.

Embodiment 2

[0035] S1. High oleic acid sunflower seed oil having mineral oil exceedance was subjected to molecular distillation, and the source of pollution was lubricating oil A with HLB 13.4. The evaporation pressure was 4 kPa, the distillation temperature was 140° C., the feeding speed was 30 drops/min, and the wiped film rotational speed was 160 rpm/min. [0036] S2. The high oleic acid sunflower seed oil (HLB 8.1) obtained after treatment in step S1 was mixed with water and AEO 9 (HLB 13.5) with stirring at 60° C. for 50 min. An emulsion was obtained. The volume ratio of the high oleic acid sunflower seed oil to the water was 1:4, and the content of AEO 9 was 1.2 wt. % of the whole system. [0037] S3. The emulsion obtained in step S2 was stood for 2 hours for layer separation to form an oil phase, an emulsified phase and an water phase. The three phases were separated, and the oil phase and the emulsified phase were respectively retained for further treatment. [0038] S4. The oil phase was treated with high-voltage pulsed electric field. The intensity of the high-voltage pulsed electric file was 40 kV/cm, the pulse width was 15 μs, and the number of pulses was 50. The oil phase was then subjected to ultrafiltration to obtain a high oleic acid sunflower seed oil I. [0039] S5. The emulsified phase was subjected to low-temperature plasma treatment, and then was treated with high-voltage pulsed electric field to break emulsion. The upper oil phase was drawn for molecular distillation to obtain a high oleic acid sunflower seed oil II. The discharge mode of the low-temperature plasma was pulse discharge, the pulse voltage peak was 40 kV, the discharge frequency was 80 HZ, the treatment time was 15 minutes, and the treatment was repeated for three times. The conditions of the high-voltage pulsed electric field were as follows: the intensity of the high-voltage pulsed electric field of 30 kV/cm, the pulse width of 5 μs, and the number of pulses of 100. The conditions of the molecular distillation were as follows: the evaporation pressure of 4 kPa, the distillation temperature of 160° C., the feeding speed of 30 drops/min, and the wiped film rotational speed of 160 rpm/min.

TABLE-US-00003 TABLE 2-1 Comparison of mineral oil contents in high oleic acid sunflower seed oil I, high oleic acid sunflower seed oil II and initial high oleic acid sunflower seed oil Initial high oleic High oleic High oleic Mineral acid sunflower acid sunflower acid sunflower oil Standard seed oil seed oil I seed oil II MOSH ≤10 ppm 108 ppm 6 ppm 10 ppm MOAH ≤2 pm  97 ppm Not detected  1 ppm (<1 ppm)

TABLE-US-00004 TABLE 2-2 Comparison of contents of other pollutants in high oleic acid sunflower seed oil I, high oleic acid sunflower seed oil II and initial high oleic acid sunflower seed oil Initial high oleic acid High oleic acid High oleic acid Other pollutants Standard sunflower seed oil sunflower seed oil I sunflower seed oil II Polycyclic aromatic  ≤10 ppb Not detected Not detected  2.8 ppb hydrocarbon (PAH 4) (<0.5 ppb ) (<0.5 ppb ) Trans fatty acids ≤2% 0.12% 0.16% 0.37% Glycidyl ester ≤1000 ppb Not detected Not detected 180 ppb (<100 ppb) (<100 ppb) 3-MPCD ≤2500 ppb Not detected Not detected 260 ppb (<100 ppb) (<100 ppb )

[0040] It can be seen from Table 2-1 that MOSH and MOAH of in the high oleic acid sunflower seed oil I and high oleic acid sunflower seed oil II obtained after treatment are reduced below the standard. It can be seen from Table 2-2 that, at the strict condition control of this process, the contents of other pollutants all meet the requirements of European Union regulations on relevant pollutant limits.

Embodiment 3

[0041] S1. The grapeseed oil having mineral oil exceedance was subjected to molecular distillation, and the source of pollution was lubricating oil B with HLB 14.0. The evaporation pressure was 5 kPa, the distillation temperature was 140° C., the feeding speed was 40 drops/min, and the wiped film rotational speed was 150 rpm/min. [0042] S2. The grape seed oil (HLB 7.3) obtained after treatment in step S1 was mixed with water and a compound emulsifier (HLB 14.0) with stirring at 60° C. for 50 minutes. The volume ratio of the grapeseed oil to the water was 1:3, and the content of the compound emulsifier was 2.5 wt. % of the whole system. The compound emulsifier was a mixture of Tween 80 and Span 60 at a ratio of 9:1. [0043] S3. The emulsion obtained in step S2 was stood for 2 hours for layer separation to form an oil phase and an emulsified phase. The two phases were separated and respectively retained for further treatment. [0044] S4. The oil phase was treated with high-voltage pulsed electric field. The intensity of the high-voltage pulsed electric file was 60 kV/cm, the pulse width was 10 μs, and the number of pulses was 60. The oil phase was then subjected to ultrafiltration to obtain a grapeseed oil I. [0045] S5. The emulsified phase was subjected to low-temperature plasma treatment, and then was treated with high-voltage pulsed electric field to break emulsion. The upper oil phase was drawn for molecular distillation to obtain a grapeseed oil II. The discharge mode of the low-temperature plasma was pulse discharge, the pulse voltage peak was 50 kV, the discharge frequency was 70 HZ, the treatment time was 15 minutes, and the treatment was repeated for twice. The conditions of the high-voltage pulsed electric field treatment were as follows: the intensity of the high-voltage pulsed electric field of 40 kV/cm, the pulse width of 15 μs, and the number of pulses of 80. The conditions of the molecular distillation were as follows: the evaporation pressure of 4 kPa, the distillation temperature of 155° C., the feeding speed of 40 drops/min, and the wiped film rotational speed of 160 rpm/min.

TABLE-US-00005 TABLE 3-1 Comparison of mineral oil contents in grapeseed oil I, grapeseed oil II and initial grapeseed oil Mineral Initial grape Grapeseed Grapeseed oil Standard seed oil oil I oil II MOSH ≤10 ppm  96 ppm 4 ppm 8 ppm MOAH ≤2 pm 123 ppm Not detected (<1 ppm) 2 ppm

TABLE-US-00006 TABLE 3-2 Comparison of contents of other pollutants in grapeseed oil I, grapeseed oil II and initial grapeseed oil Other pollutants Standard Initial grapeseed oil Grapeseed oil I Grapeseed oil II Polycyclic aromatic  ≤10 ppb Not detected Not detected  2.9 ppb hydrocarbon (PAH 4) (<0.5 ppb) (<0.5 ppb) Trans-fatty acids ≤2% 0.13% 0.17% 0.28% Glycidyl ester ≤1000 ppb Not detected Not detected 175 ppb (<100 ppb) (<100 ppb) 3-MPCD ≤2500 ppb Not detected 140 ppb 270 ppb (<100 ppb)

[0046] It can be seen from Table 3-1 that MOSH and MOAH in the grapeseed oil I and grapeseed oil II obtained after treatment are reduced below the standard. It can be seen from Table 3-2 that, at the strict condition control of this process, other pollutants all meet the requirements of European Union regulations on relevant pollutant limits.

Embodiment 4

[0047] S1. Evening primrose oil having mineral oil exceedance was subjected to molecular distillation, and the source of pollution was white oil with HLB 10.5. The evaporation pressure was 3 kPa, the distillation temperature was 140° C., the feeding speed was 35 drops/min, and the wiped film rotational speed was 160 rpm/min. [0048] S2. The evening primrose oil (HLB 7.1) obtained after treatment in step S1 was mixed with water and a compound emulsifier (HLB 10.6) with stirring at 55° C. for 45 minutes. An emulsion was obtained. The volume ratio of the evening primrose oil to the water was 1:3, and the content of the compound emulsifier was 1.8 wt. % of the whole system. The compound emulsifier was a mixture of Atlas G2127 and Tegin at a ratio of 7:3. [0049] S3. The emulsion was stood for 2 hours for layer separation to form an oil phase and an emulsion phase. The two phases were separated and respectively retained for further treatment. [0050] S4. The oil phase was stirred at 55° C. for 30 minutes, and then was frozen at 0° C. for 0.5 hour. The oil phase was then treated with high-voltage pulsed electric field. The intensity of the high-voltage pulsed electric file was 50 kV/cm, the pulse width was 10 μs, and the number of pulses was 50. The oil phase was then subjected to ultrafiltration to obtain an evening primrose oil I. [0051] S5. The emulsified phase liquid was subjected to low-temperature plasma treatment, and then was treated with high-voltage pulsed electric field to break emulsion. The upper oil phase was drawn for molecular distillation to obtain an evening primrose oil II. The discharge mode of the low-temperature plasma was pulse discharge, the pulse voltage peak was 40 kV, the discharge frequency was 60 HZ, the treatment time was 20 minutes, and the treatment was repeated for twice. The conditions of the high-voltage pulsed electric field treatment were as follows: the intensity of the high-voltage pulsed electric field of 60 kV/cm, the pulse width of 10 μs, and the number of pulses of 60. The conditions of the molecular distillation were as follows: the evaporation pressure of 4 kPa, the distillation temperature of 150° C., the feeding speed of 30 drops/min, and the wiped film rotational speed of 160 rpm/min.

TABLE-US-00007 TABLE 4-1 Comparison of mineral oil contents in evening primrose oil I, evening primrose oil II and initial evening primrose oil Evening Evening Mineral Initial evening primrose primrose oil Standard primrose oil oil I oil II MOSH ≤10 ppm 177 ppm 6 ppm 9 ppm MOAH ≤2 pm 153 ppm 1 ppm 1 ppm

TABLE-US-00008 TABLE 4-2 Comparison of contents of other pollutants in evening primrose oil I, evening primrose oil II and initial evening primrose oil Initial evening Evening Evening Other pollutants Standard primrose oil primrose oil I primrose oil II Polycyclic aromatic  ≤10 ppb Not detected Not detected  3.8 ppb hydrocarbon (PAH 4) (<0.5 ppb) (<0.5 ppb) Trans-fatty acids ≤2% 0.12% 0.18% 0.49% Glycidyl ester ≤1000 ppb Not detected 125 ppb 190 ppb (<100 ppb) 3-MPCD ≤2500 ppb Not detected 150 ppb 275 ppb (<100 ppb)

[0052] It can be seen from Table 4-1 that MOSH and MOAH in the evening primrose oil I and evening primrose oil II obtained after treatment are reduced below the set standard. It can be seen from Table 4-2 that, at the strict condition control of this process, the contents of other pollutants all meet the requirements of European Union regulations on relevant pollutant limits.