Degreased squeezed tea oil with low benzopyrene content and preparation method of degreased squeezed tea oil

Abstract

The invention provides low-benzopyrene degreased squeezed tea oil and a preparation method thereof, and belongs to the technical field of camellia oleosa seed oil processing. The preparation method comprises the following steps: mixing and squeezing camellia oleifera seed kernels and camellia oleifera shells to obtain squeezed crude camellia oleifera oil, and winterizing the squeezed crude camellia oleifera oil to obtain low-benzopyrene degreased squeezed camellia oleifera oil; the addition amount of the camellia oleifera shells is 15-25% of the weight of the camellia oleifera seed kernels. The camellia oleifera shells which are high in water holding capacity and loose in structure are adopted to replace camellia oleifera seed shells which are low in water holding capacity and compact in structure to be mixed with camellia oleifera seed kernels to be squeezed, overheating caused by friction and sharp rising of squeezing pressure in the squeezing process are effectively prevented, and loss of active ingredients of camellia oleifera seed oil is avoided; the dissolution of active substances such as polyphenol, flavone and triterpenoids in the pressed tea oil is increased, the nutritional value of the pressed tea oil is improved, the content of benzopyrene in the camellia oleifera seed oil can be effectively reduced, and the edible quality of the pressed tea oil can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of camellia oil processing, and in particular relates to low-benzopyrene defatted pressed camellia oil and a preparation method thereof. Background Art

[0002] Camellia oleifera is a woody oil unique to my country and one of the four major woody oils in the world. Camellia oil and olive oil are known as the two major woody edible oils in the world and have been known as "treasures among oils" since ancient times. Camellia oil is of better quality than olive oil. Compared with olive oil, high-grade refined camellia oil has higher nutritional and health quality. Camellia oil can effectively improve cardiovascular and cerebrovascular diseases, reduce cholesterol and fasting blood sugar, inhibit the increase of triglycerides, and help patients with "three highs" improve their health.

[0003] Benzopyrene (BaP) is a polycyclic aromatic hydrocarbon compound composed of a benzene ring and a pyrene molecule. It is a common highly active indirect carcinogen and one of the three strongest carcinogens in the world. According to the national "Sanitary Standards for Edible Vegetable Oils", the upper limit of benzopyrene content in edible oil is 10 micrograms / kilogram. Benzopyrene is an indirect product produced in the processing of tea oil. During high-temperature drying or high-temperature pressing, tea seeds are burned due to uneven local heating, causing proteins and fatty acids to react and produce benzopyrene, which seriously affects the subsequent refining and consumption of tea oil. At present, the method of removing harmful substances such as benzopyrene from tea oil mainly relies on activated carbon adsorption removal, which easily causes the loss of active ingredients such as polyphenols and flavonoids.

[0004] In addition, simply filtered pressed tea oil also contains wax substances and saturated fats with higher melting points. These waxes and saturated fats will dissolve in the oil during the production process of camellia oil. At low temperatures, they can easily cause the oil to become turbid and crystallize, seriously affecting the sensory perception of the oil as well as its taste. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a low-benzopyrene defatted pressed tea oil and a preparation method thereof, so as to solve the problems of high benzopyrene content in pressed tea oil and poor edible quality of pressed tea oil.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing low-benzopyrene defatted pressed tea oil, comprising the following steps:

[0008] The oil-tea camellia seed kernels and oil-tea camellia shells are mixed and squeezed to obtain pressed raw tea oil, and the pressed raw tea oil is winterized to obtain low-benzopyrene defatted pressed tea oil;

[0009] The added amount of the camellia oleifera shell is 15% to 25% of the weight of the camellia oleifera seed kernel.

[0010] Preferably, the particle size of the camellia oleifera shell is 2 mm to 6 mm, and the moisture content of the camellia oleifera shell is 10% to 20%.

[0011] Preferably, the winterization comprises the following steps: cooling the squeezed raw tea oil to 40-50°C, then cooling it to 2-4°C at a cooling rate of 5°C / h-8°C / h, stirring during the cooling process, and the stirring rate is 20rpm-30rpm.

[0012] Preferably, the crystal is grown after the temperature is lowered, the temperature of the crystal is 2-4° C., the time of the crystal is 10 h-12 h, stirring is performed during the crystal growing process, and the stirring rate is 11 rpm-20 rpm.

[0013] Preferably, the method for preparing camellia oleifera seed kernels comprises the following steps: drying, roasting, shelling and crushing the camellia oleifera seeds in sequence to obtain the camellia oleifera seed kernels.

[0014] Preferably, the drying temperature is 60° C. to 80° C., the drying time is 20 h to 24 h, and the moisture content of the dried tea seeds after drying is 8% to 13%.

[0015] Preferably, the baking temperature is 100° C. to 150° C., and the baking time is 1 h to 2 h.

[0016] Preferably, the hull content in the shelled camellia seed kernels is less than 2%; and the particle size of the crushed camellia seed kernels is 4 mm to 6 mm.

[0017] Preferably, the camellia seeds and camellia shells are obtained by subjecting fresh camellia fruits to hot air shelling treatment; the temperature of the hot air is 60° C. to 80° C., and the hot air time is 6 h to 10 h.

[0018] The invention also provides low-benzopyrene defatted pressed tea oil prepared by the preparation method.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The invention adopts the camellia husk with strong water holding capacity and loose structure to replace the camellia seed husk with weak water holding capacity and tight structure to mix and squeeze with the camellia seed kernel, so as to effectively prevent overheating and a sharp increase in pressing pressure due to friction during the pressing process, thereby avoiding the loss of active ingredients of the camellia seed oil, increasing the dissolution of active substances such as polyphenols, flavonoids, triterpenoid compounds and the like in the pressed camellia oil, improving the nutritional value of the pressed camellia oil, and being able to effectively reduce the content of benzopyrene in the camellia seed oil and improve the edible quality of the pressed camellia oil.

[0021] The present invention obtains pressed raw tea oil with high oil yield and low benzopyrene content through pressing and oil preparation, and converts the pressed raw tea oil into finished edible pressed tea oil with stable quality through winterization and dewaxing technology. The adopted process conditions are mild and the operation is simple, the nutritional active ingredients of the oil are greatly retained, and the stable quality of the oil is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the preparation process of low-benzopyrene defatted pressed tea oil. DETAILED DESCRIPTION

[0023] The present invention provides a method for preparing low-benzopyrene defatted pressed tea oil, comprising the following steps:

[0024] Camellia oleifera seed kernels and camellia oleifera shells are mixed and squeezed to obtain pressed raw camellia oil, and the pressed raw camellia oil is winterized to obtain low-benzopyrene defatted pressed camellia oil; the addition amount of the camellia oleifera shells is preferably 15% to 25% of the weight of the camellia oleifera seed kernels, and more preferably 18% to 22%.

[0025] In the present invention, the particle size of the oil-tea camellia shell is preferably 2mm-6mm, more preferably 3mm-5mm; the moisture content of the oil-tea camellia shell is preferably 10%-20%, more preferably 11%-19%. The preparation method of the oil-tea camellia kernel comprises the following steps: the oil-tea camellia seeds are sequentially dried, roasted, shelled and crushed to obtain the oil-tea camellia kernel; the drying temperature is preferably 60℃-80℃, more preferably 65℃-75℃; the drying time is preferably 20h-24h, more preferably 21h-23h; the moisture content of the dried oil-tea camellia seeds after drying is preferably 8%-13%, more preferably 9%-12%; the baking temperature is preferably 100℃-150℃, more preferably 110℃-140℃; the baking time is preferably 1h-2h, more preferably 1.2-1.8h; the seed shell content in the shelled oil-tea camellia kernel is less than 2%; the particle size of the crushed oil-tea camellia kernel is preferably 4mm-6mm, more preferably 5mm. The tea seeds and tea fruit shells are obtained by shelling fresh tea fruits with hot air; the temperature of the hot air is preferably 60°C to 80°C, more preferably 65°C to 75°C; the time of the hot air is preferably 6h to 10h, more preferably 7h to 9h. The winterization comprises the following steps: cooling the squeezed raw tea oil to 40-50°C, and then further cooling it to 42-48°C; cooling it to 2-4°C at a cooling rate of 5-8°C / h, and then further cooling it to 3°C; the cooling rate is preferably 6-7°C / h; stirring is performed during the cooling process, and the stirring rate is preferably 20rpm-30rpm, and more preferably 22rpm-28rpm; crystallizing is performed after the cooling, and the crystallizing temperature is preferably 2-4°C, and more preferably 3°C; the crystallizing time is preferably 10h-12h, and more preferably 10.5h-11.5h; stirring is performed during the crystallizing process, and the stirring rate is preferably 11rpm-20rpm, and more preferably 13rpm-17rpm.

[0026] The present invention also provides low-benzopyrene defatted pressed tea oil prepared by the preparation method. The preparation process flow chart of the low-benzopyrene defatted pressed tea oil is as follows: Figure 1 shown.

[0027] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0028] Example 1

[0029] 10 tons of fresh camellia oleifera fruit were weighed, and treated with hot air at 80°C for 6 hours to separate fresh camellia oleifera seeds and camellia oleifera shells with a moisture content of 10%. The camellia oleifera shells were crushed into camellia oleifera shell particles with a particle size of 2 mm. At the same time, the fresh camellia oleifera seeds were treated with hot air at 60°C for 24 hours to obtain dry camellia oleifera seeds with a moisture content of 13%. The dry camellia oleifera seeds were baked at a baking temperature of 150°C for 1 hour to obtain flavored camellia oleifera seeds. The flavored camellia oleifera seeds were dehulled to obtain flavored camellia oleifera seed kernels (the camellia oleifera kernels contained less than 2% of the seed shells). The seed kernels are further crushed to obtain crushed flavored camellia kernels with a particle size of 4 mm. To the crushed flavored camellia kernels, 5% of the weight of camellia shell particles are added with water content of 25% by weight. The mixture is fully mixed, pressed and filtered to obtain the pressed raw camellia oil. The oil temperature of the pressed raw camellia oil is controlled at 45°C, and the temperature is cooled to 3°C at a cooling rate of 8°C / h. The cooling stirring rate is 20rpm, and the crystal growing temperature is maintained at 3°C ​​for 12 hours. The crystal growing stirring rate is 20rpm, and the finished pressed camellia oil is obtained by filtration.

[0030] Example 2

[0031] 10 tons of fresh camellia oleifera fruit are weighed, and treated with hot air at 60°C for 10 hours to separate fresh camellia oleifera seeds and camellia oleifera shells with a moisture content of 20%. The camellia oleifera shells are crushed into camellia oleifera shell particles with a particle size of 4 mm. At the same time, the fresh camellia oleifera seeds are treated with hot air at 80°C for 20 hours to obtain dry camellia oleifera seeds with a moisture content of 8%. The dry camellia oleifera seeds are baked at a baking temperature of 100°C for 2 hours to obtain flavored camellia oleifera seeds. The flavored camellia oleifera seeds are dehulled to obtain flavored camellia oleifera seed kernels (the camellia oleifera kernels contain less than 2% of the hulls). The flavored camellia oleifera seeds are The kernels are further crushed to obtain crushed flavored camellia seed kernels with a particle size of 6 mm, to which are added camellia shell particles with a moisture content of 15% by weight and 10% by weight of the crushed flavored camellia seed kernels, the mixture is fully mixed, pressed and filtered to obtain pressed raw camellia oil, the oil temperature of the pressed raw camellia oil is controlled at 45°C, and the temperature is cooled to 3°C at a cooling rate of 5°C / h, the cooling stirring rate is 30 rpm, the crystal growing temperature is maintained at 3°C ​​for 10 hours, the crystal growing stirring rate is 11 rpm, and the finished camellia seed oil is obtained by filtration.

[0032] Example 3

[0033] 10 tons of fresh camellia oleifera fruit were weighed, and treated with hot air at 70°C for 8 hours to separate fresh camellia oleifera seeds and camellia oleifera shells with a moisture content of 15%. The camellia oleifera shells were crushed into camellia oleifera shell particles with a particle size of 5 mm. At the same time, the fresh camellia oleifera seeds were treated with hot air at 70°C for 22 hours to obtain dry camellia oleifera seeds with a moisture content of 10%. The dry camellia oleifera seeds were baked at a baking temperature of 130°C for 1.5 hours to obtain flavored camellia oleifera seeds. The flavored camellia oleifera seeds were dehulled to obtain flavored camellia oleifera seed kernels (the camellia oleifera kernels contained less than 2% of the seed shells). The flavored oil The tea seed kernels are further crushed to obtain crushed flavored camellia kernels with a particle size of 5 mm, to which are added camellia shell particles with a moisture content of 8% by weight and 20% by weight of the crushed flavored camellia kernels, the mixture is fully mixed, pressed and filtered to obtain pressed raw camellia oil, the oil temperature of the pressed raw camellia oil is controlled at 45°C, and the temperature is cooled to 3°C at a cooling rate of 7°C / h, the cooling stirring rate is 25 rpm, the crystal growing temperature is maintained at 3°C ​​for 11 hours, the crystal growing stirring rate is 16 rpm, and the finished camellia seed oil is obtained by filtration.

[0034] Example 4

[0035] 10 tons of fresh camellia fruit are weighed, and treated with hot air at 65°C for 9 hours to separate fresh camellia seeds and camellia shells with a moisture content of 18%. The camellia shells are crushed into camellia shell particles with a particle size of 4 mm. At the same time, the fresh camellia seeds are treated with hot air at 65°C for 23 hours to obtain dry camellia seeds with a moisture content of 12%. The dry camellia seeds are baked at a baking temperature of 140°C for 1.5 hours to obtain flavored camellia seeds. The flavored camellia seeds are dehulled to obtain flavored camellia kernels (the camellia kernels contain less than 2% of the shells). The seed kernels are further crushed to obtain crushed flavored camellia kernels with a particle size of 4 mm. Camellia oleifera shell particles with a moisture content of 11% and 22% by weight of the crushed flavored camellia kernels are added. The mixture is fully mixed, pressed and filtered to obtain pressed raw camellia oil. The oil temperature of the pressed raw camellia oil is controlled at 45°C, and the temperature is cooled to 3°C at a cooling rate of 7°C / h. The cooling stirring rate is 25 rpm, and the crystallization temperature is maintained at 3°C ​​for 11 hours. The crystallization stirring rate is 16 rpm, and the finished camellia seed oil is obtained by filtration.

[0036] Example 5

[0037] 10 tons of fresh camellia oleifera fruit were weighed, and treated with hot air at 75°C for 7 hours to separate fresh camellia oleifera seeds and camellia oleifera shells with a moisture content of 12%. The camellia oleifera shells were crushed into camellia oleifera shell particles with a particle size of 6 mm. The fresh camellia oleifera seeds were treated with hot air at 75°C for 21 hours to obtain dry camellia oleifera seeds with a moisture content of 9%. The dry camellia oleifera seeds were baked at a baking temperature of 150°C for 2 hours to obtain flavored camellia oleifera seeds. The flavored camellia oleifera seeds were dehulled to obtain flavored camellia oleifera kernels (the camellia oleifera kernels contained less than 2% of the hulls). The flavored camellia oleifera seeds were The kernels are further crushed to obtain crushed flavored camellia seed kernels with a particle size of 6 mm, to which are added camellia shell particles with a moisture content of 9% and 18% by weight of the crushed flavored camellia seed kernels, the mixture is fully mixed, pressed and filtered to obtain pressed raw camellia oil, the oil temperature of the pressed raw camellia oil is controlled at 45°C, and the temperature is cooled to 3°C at a cooling rate of 7°C / h, the cooling stirring rate is 25 rpm, the crystal growing temperature is maintained at 3°C ​​for 11 hours, the crystal growing stirring rate is 16 rpm, and the finished camellia seed oil is obtained by filtration.

[0038] Comparative Example 1

[0039] Weigh 10 tons of fresh camellia oil fruit, treat it with hot air at 80℃ for 6 hours, separate fresh camellia oil seeds and camellia oil shells with a moisture content of 10%, crush the camellia oil shells into camellia oil shell particles with a particle size of 2 mm, and simultaneously treat the fresh camellia oil seeds with hot air at 60℃ for 24 hours to obtain dry camellia oil seeds with a moisture content of 13%, bake the dry camellia oil seeds at a baking temperature of 150℃ for 1 hour to obtain flavored camellia oil seeds, remove the seed shells from the flavored camellia oil seeds to obtain flavored camellia oil seed kernels (the camellia oil seed kernels contain less than 2% seed shells), and further crush the flavored camellia oil seed kernels to obtain crushed flavored camellia oil seed kernels with a particle size of 4 mm, add camellia oil shell particles with a moisture content of 5% by weight of 25% by weight to the crushed flavored camellia oil seed kernels, mix them thoroughly, press them to make oil, and filter them to obtain finished camellia oil.

[0040] Comparative Example 2

[0041] 10 tons of fresh camellia fruit were weighed, and treated with hot air at 80°C for 6 hours to separate fresh camellia seeds and camellia shells with a moisture content of 10%. The fresh camellia seeds were treated with hot air at 60°C for 24 hours to obtain dry camellia seeds with a moisture content of 13%. The dry camellia seeds were baked at a baking temperature of 150°C for 1 hour to obtain flavored camellia seeds. Part of the camellia shells of the flavored camellia seeds were removed (the camellia shells that accounted for 25% of the weight of the flavored camellia kernels were retained), and the flavored oil from which part of the camellia shells had been removed was removed. The tea seeds are further crushed to obtain crushed flavored tea seeds with a particle size of 4 mm. After 5% rehydration (the rehydration process is to evenly spray soft water on the flavored tea seeds), they are pressed and filtered to obtain pressed raw tea oil. The oil temperature of the pressed raw tea oil is controlled at 45°C, and the temperature is cooled to 3°C at a cooling rate of 8°C / h. The cooling stirring rate is 20rpm, and the crystal growing temperature is maintained at 3°C ​​for 12 hours. The crystal growing stirring rate is 20rpm, and the finished pressed tea oil is obtained by filtration.

[0042] Comparative Example 3

[0043] Weigh 10 tons of fresh camellia fruit, treat it with hot air at 80℃ for 6h, separate fresh camellia seeds and camellia shells with a moisture content of 10%, treat the fresh camellia seeds with hot air at 60℃ for 24h to obtain dry camellia seeds with a moisture content of 13%, bake the dry camellia seeds at a baking temperature of 150℃ for 1h to obtain flavored camellia seeds, remove the seed shells from the flavored camellia seeds to obtain flavored camellia kernels, continue to crush the flavored camellia kernels to obtain crushed flavored camellia kernels with a particle size of 4mm, add camellia shells with a moisture content of 25% by weight and 5% by weight to the crushed flavored camellia kernels, mix well, squeeze and filter to obtain pressed raw camellia oil, control the oil temperature of the pressed raw camellia oil at 45℃, cool to 3℃ at a cooling rate of 8℃ / h, cool at a cooling stirring rate of 20rpm, maintain the crystallization temperature at 3℃ for 12h, and cool at a crystallization stirring rate of 20rpm, and filter to obtain the finished pressed camellia oil.

[0044] Comparative Example 4

[0045] 10 tons of fresh camellia fruit were weighed, and treated with hot air at 80°C for 6 hours to separate fresh camellia seeds and camellia shells with a moisture content of 10%. The camellia shells were crushed into camellia shell particles with a particle size of 2 mm. At the same time, the fresh camellia seeds were treated with hot air at 60°C for 24 hours to obtain dry camellia seeds with a moisture content of 13%. The dry camellia seeds were baked at a baking temperature of 150°C for 1 hour to obtain flavored camellia seeds. The flavored camellia seeds were dehulled to obtain flavored camellia kernels (the camellia kernels contained 3% of the shells at this time). The seed kernels are further crushed to obtain crushed flavored camellia kernels with a particle size of 4 mm. To the crushed flavored camellia kernels, 5% of the weight of camellia shell particles are added with water content of 25% by weight. The mixture is fully mixed, pressed and filtered to obtain the pressed raw camellia oil. The oil temperature of the pressed raw camellia oil is controlled at 45°C, and the temperature is cooled to 3°C at a cooling rate of 8°C / h. The cooling stirring rate is 20rpm, and the crystal growing temperature is maintained at 3°C ​​for 12 hours. The crystal growing stirring rate is 20rpm, and the finished pressed camellia oil is obtained by filtration.

[0046] Comparative Example 5

[0047] Weigh 10 tons of fresh camellia fruit, treat it with hot air at 80℃ for 6 hours, separate fresh camellia seeds and camellia shells with a moisture content of 10%, treat the fresh camellia seeds with hot air at 60℃ for 24 hours to obtain dry camellia seeds with a moisture content of 13%, bake the dry camellia seeds at 150℃ for 1 hour to obtain flavored camellia seeds, remove the shells from the flavored camellia seeds to obtain flavored camellia seed kernels (the camellia seed kernels now contain less than 2% shells), continue to crush the flavored camellia seed kernels to obtain crushed flavored camellia seed kernels with a particle size of 4 mm, directly press and filter to obtain pressed tea oil.

[0048] Experimental Example 1

[0049] The analysis indicators of the finished pressed tea oils prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were compared, and the test results were as follows:

[0050] 1. Oil extraction rate calculation formula

[0051] Oil extraction rate (%) = weight extracted from dry tea seeds / weight of dry tea seeds * 100%

[0052] 2. Acid value

[0053] Detection reagents: anhydrous ethanol, ether, phenolphthalein indicator, 0.01 mol / L potassium hydroxide standard titration solution

[0054] Detection steps: Weigh 5 grams of pressed tea oil into a conical flask, add anhydrous ethanol-ether mixed solution (volume ratio 1:1), add 5 drops of phenolphthalein indicator, mix well, and titrate with 0.01 mol / L potassium hydroxide standard titration solution until the solution turns slightly red and does not fade within 30 seconds, and record the volume of 0.01 mol / L potassium hydroxide standard titration solution consumed.

[0055] Calculation formula:

[0056] Where, C is the concentration of potassium hydroxide standard titration solution, mol / L;

[0057] V is the volume of potassium hydroxide standard titration solution consumed, mL;

[0058] 56.1 is the relative molecular mass of potassium hydroxide;

[0059] m is the weight of fat, g.

[0060] 3. Peroxide value

[0061] Detection reagents: glacial acetic acid, chloroform, starch indicator, saturated potassium iodide solution, sodium thiosulfate standard titration solution

[0062] Detection steps: Weigh 5 grams of squeezed tea oil into a stoppered conical flask, add glacial acetic acid-chloroform mixed solution (volume ratio 3:2), add 0.5 mL of potassium iodide saturated solution, cover with a lid and seal, react for 1 minute, add 30 mL of distilled water, then add 1 mL of starch indicator, mix well, titrate with sodium thiosulfate standard titrant, titrate until the solution becomes colorless and does not change color within 30 seconds, and record the volume of sodium thiosulfate standard titrant consumed.

[0063] Calculation formula:

[0064] Where, C is the concentration of sodium thiosulfate standard titration solution, mol / L;

[0065] V is the volume of sodium thiosulfate standard titrant consumed, mL;

[0066] 0.1269 is the mass of iodine equivalent to 1.00 mL of sodium thiosulfate standard titration solution;

[0067] 100 is the conversion factor;

[0068] m is the weight of fat, g.

[0069] 4. Benzo(α)pyrene

[0070] (1) Detection reagents: toluene, dichloroethane, acetonitrile and n-hexane, all of chromatographic grade.

[0071] (2) Detection steps;

[0072] A. Sample preparation: Weigh 0.4g (accurate to 0.001g) of sample, add 5mL of n-hexane, vortex mix for 0.5min, and use benzo(a)pyrene molecular imprinting column to be purified, and activate the column with 5mL of dichloromethane and 5mL of n-hexane in turn. Transfer the liquid to be purified into the column, and when the liquid level drops to the column bed, rinse the column with 6mL of n-hexane, discard the effluent, elute with 6mL of dichloromethane and collect the purified liquid into a test tube. Blow dry the purified liquid with nitrogen at 40℃, accurately draw 0.4mL of acetonitrile and vortex to dissolve for 0.5min, and pass it through a microporous filter membrane for liquid chromatography determination.

[0073] B. Preparation of standard curve: dilute the benzo(a)pyrene standard intermediate solution (1.0 μg / mL) with acetonitrile to obtain 0.5 ng / mL, 1.0 ng / mL, 5.0 ng / mL, 10.0 ng / mL, and 20.0 ng / mL calibration curve solutions. Prepare them before use and inject the standard series working solutions into the liquid chromatography respectively. Measure the corresponding chromatographic peaks and obtain the standard curve regression equation with the concentration of the standard series working solutions as the horizontal coordinate and the peak area as the vertical coordinate.

[0074] C. Detection: Inject the test solution and measure it to obtain the chromatographic peak area of ​​benzo(a)pyrene. Calculate the concentration of benzo(a)pyrene in the sample solution according to the standard curve regression equation.

[0075] (3) Testing conditions:

[0076] a) Chromatographic column: C18, column length 250 mm, inner diameter 4.6 mm, particle size 5 μm, or equivalent;

[0077] b) Mobile phase: acetonitrile + water = 88 + 12;

[0078] c) Flow rate: 1.0 mL / min;

[0079] d) Fluorescence detector: excitation wavelength 384nm, emission wavelength 406nm;

[0080] e) Column temperature: 35℃;

[0081] f) Injection volume: 20 μL.

[0082] 5. Total polyphenols

[0083] (1) Detection reagents: anhydrous ethanol, Folin phenol reagent, sodium carbonate, all of analytical grade; polyphenol standard (standard sample used for determination of total polyphenols, UV ≥ 98%), purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0084] (2) Detection steps:

[0085] A. Sample preparation: Weigh 20g of pressed tea oil into a flask, add 20mL of 60% ethanol solution, stir and extract at 70℃ for 1h, centrifuge, collect the supernatant, extract the pressed tea oil again with 20mL of 60% ethanol solution at 70℃ for 1h, centrifuge, collect the supernatant again, combine the two supernatants and transfer them to a 50mL volumetric flask, make up to volume with 60% ethanol solution, and wait for testing.

[0086] B. Preparation of standard curve: Dissolve the polyphenol standard in 60% ethanol solution, and prepare 40μg / mL, 60μg / mL, 80μg / mL, 100μg / mL, and 120μg / mL standard gradient solutions. Pipette 1mL of each standard gradient solution into different 10mL volumetric flasks, add 1mL of folin phenol solution and 2mL of 7.5% sodium carbonate solution respectively, shake well, dilute to the scale with distilled water, react at room temperature for 1h, measure the absorbance at a wavelength of 760nm, and draw a standard curve with absorbance as the ordinate and the polyphenol standard gradient concentration as the abscissa.

[0087] C. Detection: Pipette 5 mL of the solution to be tested into different 25 mL volumetric flasks, add 2.5 mL of Folin solution and 5 mL of 7.5% sodium carbonate solution, shake well, dilute to the mark with distilled water, react at room temperature for 1 hour, measure the absorbance at a wavelength of 760 nm, find the corresponding concentration on the standard curve based on the absorbance and calculate the content.

[0088] 6. Total flavonoids

[0089] (1) Detection reagents: anhydrous ethanol, sodium nitrite, aluminum nitrate, sodium hydroxide, all of analytical grade; rutin standard sample (standard sample used for determination of flavonoids, HPLC ≥ 98%), purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0090] (2) Detection steps:

[0091] A. Sample preparation: Weigh 20g of pressed tea oil into a flask, add 20mL of 60% ethanol solution, stir and extract at 70℃ for 1h, centrifuge, collect the supernatant, extract the pressed tea oil again with 20mL of 60% ethanol solution at 70℃ for 1h, centrifuge, collect the supernatant again, combine the two supernatants and transfer them to a 50mL volumetric flask, make up to volume with 60% ethanol solution, and wait for testing.

[0092] B. Preparation of standard curve: dissolve the rutin standard sample with 60% ethanol solution, and prepare 8μg / mL, 16μg / mL, 32μg / mL, 48μg / mL, and 64μg / mL standard gradient solutions. Pipette 1mL of each standard gradient solution and place it in different 25mL volumetric flasks. Add 60% ethanol solution to 10mL, add 1mL5% sodium nitrite solution, shake well, let stand for 6min, then add 1mL10% aluminum nitrate solution, add 10mL4% sodium hydroxide solution after 6min, mix well, and then make up to the scale with 60% ethanol solution. Shake well, let stand for 15min, and then measure the absorbance at a wavelength of 510nm. Draw a standard curve with absorbance as the ordinate and rutin standard gradient concentration as the abscissa.

[0093] C. Detection: Pipette 5mL of the solution to be tested and place it in different 25mL volumetric flasks, add 60% ethanol solution to 10mL, add 1mL of 5% sodium nitrite solution, shake well, let it stand for 6 minutes, then add 1mL of 10% aluminum nitrate solution, add 10mL of 4% sodium hydroxide solution after 6 minutes, mix well, then make up to the scale with 60% ethanol solution, shake well, let it stand for 15 minutes, and then measure the absorbance at a wavelength of 510nm. According to the absorbance, find the corresponding concentration on the standard curve and calculate the content.

[0094] 7. Total triterpenes

[0095] (1) Detection reagents: ethanol, glacial acetic acid, perchloric acid, and vanillin were all analytical grade; ursolic acid standard sample (for determination of total triterpenes, HPLC ≥ 98%) was purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0096] (2) Detection steps:

[0097] A. Sample preparation: Weigh 5 g of the pressed tea oil to be tested into a flask, add 20 mL of anhydrous ethanol, stir and extract at 70°C for 1 h, centrifuge, collect the supernatant, add 20 mL of anhydrous ethanol to the pressed tea oil to be tested again, stir and extract at 70°C for 1 h, centrifuge, collect the supernatant again, combine the two supernatants and transfer them to a 50 mL volumetric flask, make up to volume with anhydrous ethanol, and wait for testing.

[0098] B. Preparation of standard curve: Dissolve the ursolic acid standard sample in anhydrous ethanol, and prepare 10μg / mL, 20μg / mL, 40μg / mL, 60μg / mL, and 60μg / mL standard gradient solutions. Pipette 1mL of each standard gradient solution and place it in different 10mL stoppered colorimetric tubes, then place it in a boiling water bath to evaporate the solvent, add 0.4mL 5% vanillin solution (5g vanillin dissolved in 100mL glacial acetic acid) and 1mL perchloric acid respectively, mix well, then place it in a 60℃ water bath and heat for 15min, take it out and place it in an ice water bath for 2min, add 3.6mL glacial acetic acid, mix well, place it at room temperature for 10min, and measure the absorbance at a wavelength of 545nm. Use the absorbance as the ordinate and the ursolic acid standard gradient concentration as the abscissa to draw a standard curve.

[0099] C. Detection: Pipette 0.5mL of the solution to be tested into a 10mL stoppered colorimetric tube, then place it in a boiling water bath to evaporate the solvent, add 0.4mL of 5% vanillin solution (5g of vanillin dissolved in 100mL of glacial acetic acid) and 1mL of perchloric acid, mix well, then place it in a 60℃ water bath and heat for 15min, take it out and place it in an ice water bath for 2min, add 3.6mL of glacial acetic acid, mix well, place it at room temperature for 10min, and measure the absorbance at a wavelength of 545nm. According to the absorbance, find the corresponding concentration on the standard curve and calculate the content.

[0100] Experimental results: as shown in Table 1.

[0101] Table 1 Comparison results of analysis indicators of finished pressed tea oil

[0102]

[0103]

[0104] It can be seen from Table 1 that Examples 1 to 5 can effectively extract camellia oil from camellia fruit, and the acid value, peroxide value, and benzo(α)pyrene of the oil meet the quality requirements of the first-grade camellia oil in GB / T11765-2018 "Camellia Oil", and the oil extraction rate is relatively high. It is clear and transparent when stored at 20°C for 8 months, and the quality is stable, indicating that the pressed camellia oil prepared by this preparation method is of good quality and stable quality.

[0105] It can be seen from Example 1 and Comparative Example 1 that adding a winterization process is beneficial to the stability of oil storage.

[0106] It can be seen from Example 1 and Comparative Examples 2 and 3 that using low-temperature air-dried camellia nut shells instead of camellia seed shells and camellia seed kernels for pressing can increase the content of total polyphenols, total flavonoids and total triterpenes in the pressed tea oil, reduce the production of harmful substance benzo(α)pyrene, and ensure a high oil yield.

[0107] It can be seen from Example 1 and Comparative Example 4 that when low-temperature air-dried camellia nut shells are used to replace camellia seed shells and camellia seed kernels for pressing, when the camellia seed shell content in the camellia seed kernels is high, the hard texture of the camellia seed shells will cause the temperature and pressure in the oil pressing process to be too high, producing harmful substance benzo(α)pyrene.

[0108] It can be seen from Example 1 and Comparative Example 5 that the lack of a certain proportion of tea nut shells or tea seed shells will cause the oil pressing process to be slippery and no oil can be obtained. This is because the fiber structure in the tea nut shells or tea seed shells can provide pressing pressure, thereby allowing the oil to be squeezed out.

[0109] It can be seen from the above embodiments, comparative examples and experimental examples that the present invention uses low-temperature air-dried camellia husks to replace camellia seed husks and evenly mixes them with camellia seed kernels to produce oil, and combines them with a winterization process to operate at low temperatures, which not only avoids the loss of active ingredients in camellia seed oil, but also can reduce the content of benzo(α)pyrene in camellia seed oil and improve the edible quality of camellia seed oil.

[0110] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing low-benzopyrene defatted pressed tea oil, characterized in that: The following steps are involved: The oil-tea camellia seed kernels and oil-tea camellia shells are mixed and squeezed to obtain pressed raw tea oil, and the pressed raw tea oil is winterized to obtain low-benzopyrene defatted pressed tea oil; The added amount of the camellia oleifera shell is 15% to 25% of the weight of the camellia oleifera seed kernel.

2. The preparation method according to claim 1, characterized in that: The particle size of the oil-tea camellia shell is 2 mm to 6 mm, and the water content of the oil-tea camellia shell is 10% to 20%.

3. The preparation method according to claim 1, characterized in that: The winterization comprises the following steps: cooling the squeezed raw tea oil to 40-50°C, then cooling it to 2-4°C at a cooling rate of 5°C / h-8°C / h, stirring during the cooling process at a rate of 20rpm-30rpm.

4. The preparation method according to claim 3, characterized in that: The crystal is grown after the temperature is lowered, the temperature of the crystal is 2-4° C., the time of the crystal is 10 h-12 h, and stirring is performed during the crystal growing process, and the stirring rate is 11 rpm-20 rpm.

5. The preparation method according to claim 1, characterized in that: The method for preparing camellia oil seed kernels comprises the following steps: drying, roasting, shelling and crushing the camellia oil seeds in sequence to obtain the camellia oil seed kernels.

6. The preparation method according to claim 5, characterized in that: The drying temperature is 60° C. to 80° C., the drying time is 20 h to 24 h; and the moisture content of the dried tea seeds after drying is 8% to 13%.

7. The preparation method according to claim 5, characterized in that: The baking temperature is 100° C. to 150° C., and the baking time is 1 h to 2 h.

8. The preparation method according to claim 5, characterized in that: The seed shell content in the shelled camellia seed kernels is less than 2%; and the particle size of the crushed camellia seed kernels is 4 mm to 6 mm.

9. The preparation method according to claim 5, characterized in that: The oil-tea camellia seeds and oil-tea camellia fruit shells are obtained by subjecting fresh oil-tea camellia fruit to a hot air shelling treatment; the temperature of the hot air is 60° C. to 80° C., and the hot air time is 6 hours to 10 hours.

10. Low-benzopyrene defatted pressed tea oil prepared by the preparation method according to any one of claims 1 to 9.

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