Rapeseed oil capable of improving spicy taste after cooking as well as preparation method and application of rapeseed oil

Abstract

The invention relates to the field of food / non-staple food processing, and discloses rapeseed oil capable of improving spicy taste after cooking as well as a preparation method and application of the rapeseed oil. The method comprises the following steps: (1) shelling rapeseeds to obtain rapeseed kernels and rapeseed shells; (2) mixing the rapeseed kernels and the rapeseed hulls, and performing squeezing treatment to obtain rapeseed oil; in the step (2), based on the total dry basis weight of the rapeseed kernels and the rapeseed hulls, the use amount of the rapeseed kernels accounts for 80-95 wt%, and the use amount of the rapeseed hulls accounts for 5-20 wt%. The rapeseed oil is prepared from the rapeseed kernels and the rapeseed shells in a specific proportion, and the content of isothiocyanate in the rapeseed oil can be increased to 30 mg / kg, so that the pungency degree and the numb degree of the sense organ during cooking of Sichuan dishes are enhanced; the linseed oil prepared by the method disclosed by the invention is high in oil yield and suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the field of food / side food processing, and in particular to rapeseed oil and a preparation method and application thereof. Background Art

[0002] The weight of rapeseed hulls is about 12-20% of the whole seed, and the crude fiber content in rapeseed hulls is about 30-40% of the weight of the whole seed. Compared with rapeseed kernels, the hulls are rich in tannins, phytic acid, pigments, etc. The traditional oil-making process uses shell pressing, and the crude rapeseed oil obtained is very dark in color. The substances in the shells migrate into the oil, which reduces the quality of the oil and increases the difficulty of refining.

[0003] After rapeseed is shelled and processed into oil, most of the phytic acid, tannins, pigments, crude fiber and other substances can be removed, and the protein content is increased. Because glucosinolates are mainly found in rapeseed kernels, the content of Maillard reaction substrates is higher during the seed frying process after shelling, and the prepared rapeseed oil has a richer flavor, lighter oil color, and lower content of substances such as phospholipids and free fatty acids, saving resource waste in the refining process. However, when the shelling rate is too high, the chamber pressure during the pressing process is also low, resulting in reduced elasticity of the oil itself, reduced effective oil production time, and lower oil production rate. Therefore, after the rapeseed shell and kernel are separated, a portion of rapeseed oil should be added to increase the chamber pressure and improve the oil production rate.

[0004] CN106833871A discloses a production process of fragrant rapeseed oil, which includes: after the rapeseed absorbs water uniformly, microwave frying is used to separate the kernel and shell of the rapeseed; the rapeseed kernel is squeezed by an oil press to obtain the first squeezed crude oil and rapeseed kernel cake; the rapeseed kernel cake is crushed, and then mixed with the rapeseed shell to obtain a mixture, and then microwave frying is used; the mixture is squeezed by an oil press to obtain a secondary squeezed crude oil; the first squeezed crude oil and the secondary squeezed crude oil are mixed to obtain fragrant rapeseed oil. Although the method uses rapeseed shells to squeeze oil, the rapeseed shells and rapeseed kernel cakes are mixed for secondary squeezing in the method, which has the problems of low oil yield, dark color of the obtained rapeseed oil, and increased difficulty in refining.

[0005] At present, the research on rapeseed shelling mainly focuses on the shelling equipment, and there is little research on the properties of oil after shelling, especially the cooking application of oil.

[0006] Therefore, it is urgent to find a method for preparing rapeseed oil that can increase the content of isothiocyanate in rapeseed oil, thereby improving product quality and enhancing the sensory spiciness and numbness when cooking Sichuan cuisine. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems that the content of isothiocyanate in rapeseed oil in the prior art is low, resulting in weak sensory spiciness and numbness when cooking Sichuan cuisine; and excessive rapeseed shelling leads to low oil yield. A rapeseed oil and a preparation method and application thereof are provided. The method can increase the content of isothiocyanate in rapeseed oil while obtaining a high oil yield, thereby enhancing the sensory spiciness and numbness when cooking Sichuan cuisine.

[0008] In order to achieve the above object, the present invention provides a method for preparing rapeseed oil in a first aspect, wherein the method comprises the following steps:

[0009] (1) shelling rapeseed to obtain rapeseed kernels and rapeseed hulls;

[0010] (2) mixing the rapeseed kernels and rapeseed hulls, and pressing the mixture to obtain rapeseed oil;

[0011] In step (2), based on the total dry weight of the rapeseed kernels and rapeseed hulls, the rapeseed kernels are used in an amount of 80wt%-95wt%, and the rapeseed hulls are used in an amount of 5wt%-20wt%.

[0012] The second aspect of the present invention provides the application of the above preparation method in increasing the content of isothiocyanate in rapeseed oil and the oil yield.

[0013] A third aspect of the present invention provides rapeseed oil, wherein the rapeseed oil is prepared by the above-mentioned preparation method.

[0014] Through the above technical solution, the present invention achieves the following beneficial technical effects:

[0015] (1) The rapeseed oil prepared by the present invention using rapeseed kernels and rapeseed husks in a specific ratio can increase the content of isothiocyanate in the rapeseed oil to 30 mg / kg, thereby enhancing the sensory spiciness and numbing degree when cooking Sichuan cuisine.

[0016] (2) The linseed oil prepared by the method of the present invention has a high oil yield and is suitable for large-scale production. DETAILED DESCRIPTION

[0017] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0018] A first aspect of the present invention provides a method for preparing rapeseed oil, wherein the method comprises the following steps:

[0019] (1) shelling rapeseed to obtain rapeseed kernels and rapeseed hulls;

[0020] (2) mixing the rapeseed kernels and rapeseed hulls, and pressing the mixture to obtain rapeseed oil;

[0021] In step (2), based on the total dry weight of the rapeseed kernels and rapeseed hulls, the rapeseed kernels are used in an amount of 80wt%-95wt%, and the rapeseed hulls are used in an amount of 5wt%-20wt%.

[0022] In the present invention, by using rapeseed oil prepared from rapeseed kernels and rapeseed shells in a specific ratio, the content of isothiocyanate in the rapeseed oil can be increased to 30 mg / kg, thereby enhancing the sensory spiciness and numbness when cooking Sichuan cuisine; on the other hand, the oil yield of linseed oil can be increased.

[0023] In the present invention, there is no particular limitation on the machine for shelling, and any machine that can achieve shelling can be used. For example, a shelling separator can be used for shelling, and the shelling separator is purchased from Lushan County Huayu Wantong Engineering Technology Co., Ltd., and the instrument model is QMJ-300D.

[0024] Furthermore, based on the total dry weight of the rapeseed kernels and rapeseed hulls, in step (2), the rapeseed kernels are used in an amount of 85wt%-90wt%, and the rapeseed hulls are used in an amount of 10wt%-15wt%.

[0025] According to some embodiments of the present invention, the method further comprises drying the rapeseed before shelling, wherein the drying process makes the moisture content of the dried rapeseed be 4wt%-10wt%, preferably 5wt%-7wt%.

[0026] In the present invention, when the drying process makes the moisture content of the dried rapeseed meet the above range, the interaction force between the rapeseed husk and the rapeseed kernel can be reduced, which is more conducive to the complete separation of the rapeseed kernel and the rapeseed husk; when the moisture content of the rapeseed is greater than 10wt%, the toughness of the rapeseed husk is relatively large, resulting in increased difficulty in separating the rapeseed kernel and the rapeseed husk; when the moisture content of the rapeseed is less than 4wt%, it is easy to cause excessive shelling of the rapeseed, increase the powder content, and increase the difficulty in separating the rapeseed kernel and the rapeseed husk.

[0027] In the present invention, the moisture content of dried rapeseed refers to GB 5009.236-2016 "Determination of Water Content and Volatile Matter in Animal and Plant Oils and Fats".

[0028] According to some embodiments of the present invention, the conditions for the drying treatment include: a drying temperature of 50-70° C., and a drying time of 30-60 min per 1 kg of rapeseed.

[0029] Furthermore, the drying conditions include: a drying temperature of 55-65° C. and a drying time of 35-55 min per 1 kg of rapeseed.

[0030] According to some embodiments of the present invention, the method further comprises frying the mixed rapeseed kernels and rapeseed hulls before the pressing process, and the frying conditions include: a temperature of 150-180° C. and a time of 20-40 min.

[0031] Furthermore, the method further comprises frying the mixed rapeseed kernels and rapeseed husks before the pressing process, wherein the frying conditions include: a temperature of 160-170°C ， The time is 25-35 minutes.

[0032] In the present invention, there is no particular limitation on the machine for frying, and any machine that can achieve frying is acceptable. For example, a seed frying machine can be used for squeezing, and the seed frying machine is purchased from NPL Company of South Korea, and the instrument model is NPL-304G.

[0033] According to some embodiments of the present invention, there is no particular limitation on the machine for the pressing process, and any machine that can achieve physical pressing can be used. For example, a screw oil press can be used for the pressing process, and the screw oil press is purchased from Komet, Germany, and the instrument model is CA59G.

[0034] The second aspect of the present invention provides the use of the above preparation method in increasing the isothiocyanate content and oil yield in rapeseed oil (the oil yield of rapeseed oil prepared by pressing rapeseed).

[0035] In the present invention, the isothiocyanate is obtained by degradation reaction of glucosinolate in rapeseed kernel.

[0036] In the present invention, the oil yield is determined by weighing the ratio of the mass of oil after pressing to the mass of raw materials before pressing. The weighing instrument model is an AR323cN electronic balance of German GERSTEL company. The calculation formula is: oil yield = mass of crude oil after pressing / mass of raw materials for frying.

[0037] The third aspect of the present invention provides a rapeseed oil, wherein the rapeseed oil is prepared by the above-mentioned preparation method;

[0038] Preferably, the rapeseed oil comprises isothiocyanates.

[0039] More preferably, based on the total weight of the rapeseed oil, the content of the isothiocyanate is 30-200 mg / kg.

[0040] According to some embodiments of the present invention, the isothiocyanate contains at least one of 3-butenyl isothiocyanate, allyl isothiocyanate and 4-isothiocyanate-1-butene.

[0041] In the present invention, isothiocyanate is obtained by degradation reaction of glucosinolate in rapeseed kernel, and the content of isothiocyanate is determined by gas chromatography-mass spectrometry (GC-MS), and the gas chromatography-mass spectrometry (GC-MS) instrument is purchased from Agilent, USA, and the instrument model is 7890B-5977B. The specific determination method is as follows:

[0042] Add 5g of rapeseed oil sample to a 20mL headspace bottle, add 1μL of 2-methyl-3-heptanone (mass concentration of 41mg / mL) as an internal standard, mix and seal. The sample was placed in a constant temperature water bath for 30min, the water bath temperature was set to 60℃, and then inserted into a solid phase microextraction fiber head (CAR / DVB / PDMS) for headspace adsorption for 40min. After the adsorption was completed, the extraction head was inserted into the gas chromatography injection port and desorbed at 250℃ for 5min.

[0043] Gas chromatography conditions: DB.WAX column (30m×0.25mm, 0.25μm); heating program: initial temperature 40°C, maintain the temperature for 3min, first increase the temperature to 200°C at 5°C / min, then increase the temperature to 230°C at 15°C / min, and maintain the temperature for 3min, the carrier gas is helium, the constant flow rate is 1.6mL / min, the injection port temperature is 250°C, and there is no split.

[0044] Mass spectrometry conditions: electron ionization source; electron energy 70 eV, transfer line temperature 280 °C, ion source temperature maintained at 230 °C, quadrupole temperature 150 °C, mass scan range 40-250 m / z, solute delay 3 mill.

[0045] Qualitative method of compounds: Based on the peak area of ​​the compounds, the internal standard method was used for quantitative analysis, and the relative content of isothiocyanate in rapeseed oil was calculated according to formula (I).

[0046]

[0047] In formula (I): C x is the mass concentration of isothiocyanate, mg / kg.

[0048] C i is the mass concentration of the internal standard, mg / mL.

[0049] A x is the peak area of ​​isothiocyanate.

[0050] A i is the peak area of ​​the internal standard.

[0051] According to a particularly preferred embodiment of the present invention, a method for preparing rapeseed oil is provided, the method comprising the following steps:

[0052] (1) drying 1 kg of rapeseed SC at 57-63° C. for 40-50 min to obtain dried rapeseed SC, and pouring the dried rapeseed SC into a shelling separator for shelling to obtain rapeseed kernels and rapeseed hulls, wherein the moisture content of the dried rapeseed SC is 5.5-6.5 wt %;

[0053] (2) pouring the rapeseed kernels and rapeseed husks into a seed roasting machine and roasting them at 163-167° C. for 27-32 minutes, and pouring the roasted rapeseed kernels and rapeseed husks into a screw oil press for pressing to obtain rapeseed oil. In step (2), based on the total dry weight of the rapeseed kernels and rapeseed husks, the amount of rapeseed kernels accounts for 86-88wt%, and the amount of rapeseed husks accounts for 12-14wt%.

[0054] The present invention will be described in detail below through examples.

[0055] Rapeseed AH (glucosinolate content 38.62 μmol / g, produced in Anhui).

[0056] Rapeseed HB (glucosinolate content 26.29 μmol / g, origin Hubei).

[0057] Rapeseed SC (glucosinolate content 87.35 μmol / g, origin Sichuan).

[0058] The shelling separator was purchased from Lushan County Huayu Wantong Engineering Technology Co., Ltd., and the instrument model is QMJ-300D.

[0059] The moisture content of dried rapeseed is determined according to GB 5009.236-2016 "Determination of moisture and volatile matter in animal and vegetable oils and fats".

[0060] The seed roasting machine was purchased from NPL Company of South Korea, and the instrument model is NPL-304G.

[0061] The screw oil press was purchased from Komet, Germany, and the instrument model is CA59G.

[0062] The test method for the content of isothiocyanate is as follows:

[0063] The gas chromatography-mass spectrometry (GC-MS) method was used for determination. The gas chromatography-mass spectrometry (GC-MS) instrument was purchased from Agilent, USA, and the instrument model was 7890B-5977B. The specific determination method includes:

[0064] Add 5g of rapeseed oil sample to a 20mL headspace bottle, add 1μL of 2-methyl-3-heptanone (mass concentration of 41mg / mL) as an internal standard, mix and seal. The sample was placed in a constant temperature water bath for 30min, the water bath temperature was set to 60℃, and then inserted into a solid phase microextraction fiber head (CAR / DVB / PDMS) for headspace adsorption for 40min. After the adsorption was completed, the extraction head was inserted into the gas chromatography injection port and desorbed at 250℃ for 5min.

[0065] Gas chromatography conditions: DB.WAX column (30m×0.25mm, 0.25μm); heating program: initial temperature 40°C, maintain the temperature for 3min, first increase the temperature to 200°C at 5°C / min, then increase the temperature to 230°C at 15°C / min, and maintain the temperature for 3min, the carrier gas is helium, the constant flow rate is 1.6mL / min, the injection port temperature is 250°C, and there is no split.

[0066] Mass spectrometry conditions: electron ionization source; electron energy 70 eV, transfer line temperature 280 °C, ion source temperature maintained at 230 °C, quadrupole temperature 150 °C, mass scan range 40-250 m / z, solute delay 3 mill.

[0067] Qualitative method of compounds: Based on the peak area of ​​the compounds, the internal standard method was used for quantitative analysis, and the relative content of isothiocyanate in rapeseed oil was calculated according to formula (I).

[0068]

[0069] In formula (I): C x is the mass concentration of isothiocyanate, mg / kg.

[0070] C i is the mass concentration of the internal standard, mg / mL.

[0071] A x is the peak area of ​​isothiocyanate.

[0072] A i is the peak area of ​​the internal standard.

[0073] Example 1

[0074] This example is used to illustrate the preparation of rapeseed oil using the method described in the present invention.

[0075] (1) drying 1 kg of rapeseed SC at 60° C. for 45 min to obtain dried rapeseed SC, and pouring the dried rapeseed SC into a shelling separator for shelling to obtain rapeseed kernels and rapeseed hulls, wherein the moisture content of the dried rapeseed SC is 6 wt %;

[0076] (2) pouring the rapeseed kernels and rapeseed husks into a seed roaster and roasting them at 165° C. for 30 minutes, and pouring the roasted rapeseed kernels and rapeseed husks into a screw oil press for pressing to obtain rapeseed oil A1. In step (2), based on the total dry weight of the rapeseed kernels and rapeseed husks, the amount of rapeseed kernels used accounts for 87wt%, and the amount of rapeseed husks used accounts for 13wt%.

[0077] Example 2

[0078] This example is used to illustrate the preparation of rapeseed oil using the method described in the present invention.

[0079] (1) drying 1 kg of rapeseed SC at 55° C. for 35 min to obtain dried rapeseed SC, and pouring the dried rapeseed SC into a shelling separator for shelling to obtain rapeseed kernels and rapeseed hulls, wherein the moisture content of the dried rapeseed SC is 7 wt %;

[0080] (2) pouring the rapeseed kernels and rapeseed husks into a seed roasting machine and roasting them at 160° C. for 25 minutes, and pouring the roasted rapeseed kernels and rapeseed husks into a screw oil press for pressing to obtain rapeseed oil A2. In step (2), based on the total dry weight of the rapeseed kernels and rapeseed husks, the amount of rapeseed kernels accounts for 85wt%, and the amount of rapeseed husks accounts for 15wt%.

[0081] Example 3

[0082] This example is used to illustrate the preparation of rapeseed oil using the method described in the present invention.

[0083] (1) drying 1 kg of rapeseed SC at 65° C. for 55 min to obtain dried rapeseed SC, and pouring the dried rapeseed SC into a shelling separator for shelling to obtain rapeseed kernels and rapeseed hulls, wherein the moisture content of the dried rapeseed SC is 5 wt %;

[0084] (2) pouring the rapeseed kernels and rapeseed husks into a seed roaster and roasting them at 170° C. for 35 minutes, and pouring the roasted rapeseed kernels and rapeseed husks into a screw oil press for pressing to obtain rapeseed oil A3. In step (2), based on the total dry weight of the rapeseed kernels and rapeseed husks, the amount of rapeseed kernels accounts for 90wt%, and the amount of rapeseed husks accounts for 10wt%.

[0085] Example 4

[0086] This example is used to illustrate the preparation of rapeseed oil using the method described in the present invention.

[0087] (1) drying 1 kg of rapeseed SC at 50° C. for 30 min to obtain dried rapeseed SC, and pouring the dried rapeseed SC into a shelling separator for shelling to obtain rapeseed kernels and rapeseed hulls, wherein the moisture content of the dried rapeseed SC is 9 wt %;

[0088] (2) pouring the rapeseed kernels and rapeseed husks into a seed roasting machine and roasting them at 150° C. for 20 minutes, and pouring the roasted rapeseed kernels and rapeseed husks into a screw oil press for pressing to obtain rapeseed oil A4. In step (2), based on the total dry weight of the rapeseed kernels and rapeseed husks, the amount of rapeseed kernels accounts for 80wt%, and the amount of rapeseed husks accounts for 20wt%.

[0089] Example 5

[0090] This example is used to illustrate the preparation of rapeseed oil using the method described in the present invention.

[0091] (1) drying 1 kg of rapeseed SC at 60° C. for 30 min to obtain dried rapeseed SC, and pouring the dried rapeseed SC into a shelling separator for shelling to obtain rapeseed kernels and rapeseed hulls, wherein the moisture content of the dried rapeseed SC is 8 wt %;

[0092] (2) pouring the rapeseed kernels and rapeseed husks into a seed roasting machine and roasting them at 160° C. for 35 minutes, and pouring the roasted rapeseed kernels and rapeseed husks into a screw oil press for pressing to obtain rapeseed oil A5. In step (2), based on the total dry weight of the rapeseed kernels and rapeseed husks, the amount of rapeseed kernels used accounts for 95wt%, and the amount of rapeseed husks used accounts for 5wt%.

[0093] Example 6

[0094] Rapeseed oil was prepared according to the method of Example 1, except that in step (1), the oilseed SC was replaced by rapeseed AH to obtain rapeseed oil A6.

[0095] Example 7

[0096] Rapeseed oil was prepared according to the method of Example 1, except that in step (1), the oilseed SC was replaced by rapeseed HB to obtain rapeseed oil A7.

[0097] Comparative Example 1

[0098] Rapeseed oil was prepared according to the method of Example 2, except that in step (2), the amount of rapeseed kernels accounted for 97 wt % and the amount of rapeseed hulls accounted for 3 wt %, to obtain rapeseed oil D1.

[0099] Comparative Example 2

[0100] Rapeseed oil was prepared according to the method of Example 2, except that in step (1), no shelling treatment was performed (the rapeseed hull content of rapeseed was about 25 wt%), to obtain rapeseed oil D2.

[0101] Comparative Example 3

[0102] The oil was pressed according to the method of Example 1 in CN106833871A to obtain rapeseed oil D3.

[0103] Test Example 1

[0104] The isothiocyanate content, oil yield, color of rapeseed oil in the above examples and comparative examples, and the evaluation of sensory spiciness and numbing degree of rapeseed oil when cooking Sichuan cuisine were measured respectively. The results are shown in Table 1.

[0105] The content of glucosinolate degradation products was determined by gas chromatography-mass spectrometry (GC-MS). The gas chromatography-mass spectrometry (GC-MS) instrument was purchased from Agilent, USA, and the instrument model was 7890B-5977B. The specific determination method includes:

[0106] Add 5g of rapeseed oil sample to a 20mL headspace bottle, add 1μL of 2-methyl-3-heptanone (mass concentration of 41mg / mL) as an internal standard, mix and seal. The sample was placed in a constant temperature water bath for 30min, the water bath temperature was set to 60℃, and then inserted into a solid phase microextraction fiber head (CAR / DVB / PDMS) for headspace adsorption for 40min. After the adsorption was completed, the extraction head was inserted into the gas chromatography injection port and desorbed at 250℃ for 5min.

[0107] Gas chromatography conditions: DB.WAX column (30m×0.25mm, 0.25μm); heating program: initial temperature 40°C, maintain the temperature for 3min, first increase the temperature to 200°C at 5°C / min, then increase the temperature to 230°C at 15°C / min, and maintain the temperature for 3min, the carrier gas is helium, the constant flow rate is 1.6mL / min, the injection port temperature is 250°C, and there is no split.

[0108] Mass spectrometry conditions: electron ionization source; electron energy 70 eV, transfer line temperature 280 °C, ion source temperature maintained at 230 °C, quadrupole temperature 150 °C, mass scan range 40-250 m / z, solute delay 3 mill.

[0109] Qualitative method of compounds: Based on the peak area of ​​the compounds, the internal standard method was used for quantitative analysis, and the relative content of isothiocyanate in rapeseed oil was calculated according to formula (I).

[0110]

[0111] In formula (I): C xis the mass concentration of isothiocyanate, mg / kg.

[0112] C i is the mass concentration of the internal standard, mg / mL.

[0113] A x is the peak area of ​​isothiocyanate.

[0114] A i is the peak area of ​​the internal standard.

[0115] The oil yield is determined by weighing the ratio of the mass of oil after pressing to the mass of raw materials before pressing. The weighing instrument is an AR323cN electronic balance from the German GERSTEL company. The calculation formula is: Oil yield = mass of crude oil after pressing / mass of raw materials for frying.

[0116] Sensory evaluation of color: The rapeseed oil prepared in the above embodiment and comparative example was subjected to sensory evaluation of color according to the following method: an evaluation group consisting of 12 sensory personnel with rich experience in sensory evaluation scored the color of the rapeseed oil and took the average value, the sensory color score: 1 point: off-white; 2 points: light yellow; 3 points: golden yellow; 4 points: dark yellow; 5 points: brown; the sensory color score was between 3-3.7 points, the color of the rapeseed oil was golden yellow, the color was good, above 3.7 points the color was darker, below 3 points the color was lighter; the specific evaluation results are shown in Table 1.

[0117] Test Example 2

[0118] The content of glucosinolate degradation products in rapeseed oil in the above examples and comparative examples and the evaluation of sensory spiciness and numbing degree of rapeseed oil when cooking Sichuan cuisine were respectively measured. The specific evaluation results are shown in Table 2.

[0119] Sensory evaluation of spiciness: The evaluation group consisted of 12 sensory personnel with rich experience in sensory evaluation. They evaluated the cooked oil after filtering the dishes and scored them and took the average value. The sensory score for spiciness is: 1 point: not spicy; 2 points: slightly spicy; 3 points: spicy; 4 points: very spicy; 5 points: extra spicy. The higher the sensory score for spiciness, the greater the increase in sensory spiciness when cooking Sichuan cuisine. For example, when the sensory evaluation score for spiciness is 3.5, the increase in sensory spiciness when cooking Sichuan cuisine is greater than when the sensory evaluation score for spiciness is less than 3.5. The greater the difference, the greater the increase.

[0120] Sensory evaluation of numbness: The evaluation group consists of 12 sensory personnel with rich experience in sensory evaluation. They evaluate the cooked oil after filtering the dishes and take the average score. The sensory score of numbness is: 1 point: not numb; 2 points: slightly numb; 3 points: numb; 4 points: very numb; 5 points: extremely numb. The higher the sensory score of numbness, the stronger the increase in sensory numbness when cooking Sichuan cuisine. For example, when the sensory evaluation score of numbness is 3.5, the increase in sensory numbness when cooking Sichuan cuisine is stronger than when the sensory evaluation score of numbness is less than 3.5. The larger the difference, the stronger the increase.

[0121] The specific preparation method of the cooked oil after filtering the dishes is as follows:

[0122] Cooking experiment 1: Dice the tofu and soak it in boiling water with 10g of salt for about 10 minutes. Chop the beef into minced meat, cut the garlic sprouts into about 3cm sections, mince the garlic, and weigh the remaining seasonings. Add 40g of oil to the pot, heat at 1000W for 40s, turn to 1500W and stir-fry the minced meat (about 20-30s), then add 2g of salt and cooking wine and stir-fry until crispy and fragrant (stir-fry for about 70s after adding cooking wine). Add 100g of oil, heat at 2100W for 30s, then turn to 1500W, pour in Pixian bean paste, chili powder, minced garlic, and fermented black beans and stir-fry until fragrant (about 30s). Pour in fresh soup, soy sauce, tofu, and minced meat, and cook at 2100W for 90s. Add water starch, garlic sprouts, and pepper powder, and simmer at 2100W for 30s. Filter the dishes and collect the cooked oil for later use.

[0123] Cooking experiment 2: Cut the pepper into sections and set aside. Soak 30g of pepper in hot water for about 3 minutes. Soak bean sprouts in hot water for about 3 minutes. Heat the pan at 2100W for 10 seconds, pour in 200g of oil, heat at 2100W for 1min30s, add garlic and ginger slices and stir-fry for about 15s, pour in scallion segments, bean paste, pepper powder, and 30g of dried pepper segments soaked in hot water and continue to stir-fry for 30s. Add 200g of hot water, put bean sprouts to the bottom of the pot, and cook at 2100W for 3min. Add fish fillets and heat at 2100W for 60s. Pour all the ingredients in the pot into a bowl, heat 100g of oil in another pot, heat at 2100W for 1min, add 20g of pepper and 20g of green peppercorns and fry at 2000W for 30s, stirring constantly. Finally, pour it on the fish. Filter the dish and collect the cooked oil for later use.

[0124] Table 1

[0125]

[0126] Table 2

[0127]

[0128] It can be seen from the results in Table 1-2 that the preparation method of Examples 1-5 of the present invention improves the oil yield and can also increase the content of isothiocyanate in rapeseed oil, thereby enhancing the sensory spiciness and numbness when cooking Sichuan cuisine.

[0129] Comparing Examples 6-7 with Example 1, it can be seen that although the oil yield is high, the isothiocyanate content is low. Since the glucosinolate content of rapeseed AH and rapeseed HB is low, the increase in sensory spiciness and numbness when cooking Sichuan cuisine is weak.

[0130] By comparing Comparative Example 1 with Example 1, it can be seen that in Comparative Example 1, the proportion of rapeseed kernels is 97wt%, and the proportion of rapeseed hulls is 3wt%. The proportion of rapeseed hulls is too low, resulting in a low content of isothiocyanates in rapeseed oil, a low oil yield, and a weak increase in sensory spiciness and numbness when cooking Sichuan cuisine.

[0131] By comparing Comparative Example 2 with Example 1, it can be seen that in Comparative Example 1, no shelling treatment is performed, and the proportion of rapeseed shells is too high, resulting in a lower content of isothiocyanates in the rapeseed oil, a lower oil yield, a darker color, and a weaker increase in sensory spiciness and numbness when cooking Sichuan cuisine.

[0132] Comparison of Comparative Example 3 with Example 1 shows that the rapeseed hull and rapeseed kernel cake are mixed and pressed twice, resulting in a lower oil yield and a darker color, and a weaker increase in sensory spiciness and numbness when cooking Sichuan cuisine.

[0133] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing rapeseed oil, characterized in that: The method comprises the following steps: (1) shelling rapeseed to obtain rapeseed kernels and rapeseed hulls; (2) mixing the rapeseed kernels and rapeseed hulls, and pressing the mixture to obtain rapeseed oil; In step (2), based on the total dry weight of the rapeseed kernels and rapeseed hulls, the rapeseed kernels are used in an amount of 80wt%-95wt%, and the rapeseed hulls are used in an amount of 5wt%-20wt%.

2. The preparation method according to claim 1, wherein In step (2), based on the total dry weight of the rapeseed kernels and rapeseed hulls, the rapeseed kernels are used in an amount of 85wt%-90wt%, and the rapeseed hulls are used in an amount of 10wt%-15wt%.

3. The preparation method according to claim 1 or 2, wherein The method further comprises drying the rapeseed before shelling, wherein the drying process makes the moisture content of the dried rapeseed be 4-10wt%, preferably 5-7wt%.

4. The preparation method according to claim 3, wherein: The drying conditions include: a drying temperature of 50-70° C. and a drying time of 30-60 min per 1 kg of rapeseed.

5. The preparation method according to claim 4, wherein The drying conditions include: a drying temperature of 55-65° C. and a drying time of 35-55 min per 1 kg of rapeseed.

6. The preparation method according to any one of claims 1 to 5, wherein: The method further comprises frying the mixed rapeseed kernels and rapeseed hulls before the pressing process, wherein the frying conditions include: a temperature of 150-180° C. and a time of 20-40 minutes.

7. The preparation method according to any one of claims 1 to 6, wherein: The method further comprises frying the mixed rapeseed kernels and rapeseed hulls before the pressing process, wherein the frying conditions include: a temperature of 160-170° C. and a time of 25-35 minutes.

8. Use of the preparation method according to any one of claims 1 to 7 in increasing the content of isothiocyanate and the oil yield in rapeseed oil.

9. A rapeseed oil, characterized in that The rapeseed oil is prepared by the preparation method according to any one of claims 1 to 7; Preferably, the rapeseed oil comprises isothiocyanate; More preferably, based on the total weight of the rapeseed oil, the content of the isothiocyanate is 30-200 mg / kg.

10. The rapeseed oil according to claim 9, wherein The isothiocyanate contains at least one of 3-butenyl isothiocyanate, allyl isothiocyanate and 4-isothiocyanate-1-butene.

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