High-quality special sesame oil and preparation method thereof

Abstract

The invention relates to the technical field of edible oil processing, and discloses high-quality special sesame oil and a preparation method thereof.The method comprises the following steps that 1, under the condition that the oxygen concentration is lower than 0.5 v%, an oil material and first edible oil are mixed and then subjected to first-stage heating and second-stage heating in sequence, and a first solid-liquid mixture is obtained; (2) carrying out first solid-liquid separation on the first solid-liquid mixture to obtain first clear oil and first oil residues; wherein the first-stage heating is carried out under negative pressure, and the second-stage heating is carried out under normal pressure; the temperature of the first-stage heating is 30-160 DEG C lower than that of the second-stage heating. The vegetable oil prepared by the method is high in nutrient substance and flavor substance content, low in benzopyrene content, low in acid value and peroxide value, less in oil smoke during cooking, short in processing time and high in aroma production efficiency and nutrient substance extraction rate; in addition, the plant oil prepared by the method does not need to be hydrated and degummed, and the phosphorus content in the plant oil is low.

Description

Technical Field

[0001] The invention relates to the technical field of edible oil processing, and in particular to high-quality special fragrant oil and a preparation method thereof. Background Art

[0002] my country is a major consumer of flavor oils and fats, with traditional flavor oils such as peanut oil, rapeseed oil, and linseed oil being the main sources. The production of aroma substances in flavor oils mainly comes from thermal reactions during oil processing, which can be manifested in the following three aspects: (1) After the raw materials are heated, the reducing sugars and amino acids in them undergo Maillard reactions to produce aroma substances such as nitrogen-containing heterocyclic compounds represented by pyrazine; (2) the natural characteristic components contained in the raw materials undergo degradation reactions under high temperature to produce volatile flavor substances; (3) the oil in the raw materials undergoes oxidation and cracking to produce small molecular flavor substances such as aldehydes, ketones, and acids. After the raw materials are heated to produce aroma, they enter the press to squeeze out the oil to obtain crude oil, which is then purified through processes such as filtration and hydration degumming to become concentrated flavor oil. In the entire process, heating is the key aroma production process, which determines the generation of aroma; purification is the key aroma retention process, which determines the degree of retention of the generated aroma substances. Therefore, studying the aroma production process and aroma retention process is crucial for the production of flavor oils.

[0003] Currently, the aroma production processes for oils and fats are mainly divided into traditional thermal aroma production and new enzyme-assisted thermal aroma production. Traditional thermal aroma production methods mainly involve drum roasting, hot air baking, microwave baking, and other methods to produce aroma. For example, CN113528227A, CN11565175A, and CN115678666A report on the use of microwave, steam, hot air, infrared, and other methods for aroma production. New aroma production methods mainly use enzyme preparations or enzymes produced by microbial fermentation to treat the oil or add flavor precursors to the oil to enhance the flavor of the oil. For example, CN106883926A, CN111378523A, and CN113897240A report on these methods.

[0004] However, because edible oil processing standards and regulations do not explicitly permit the use of enzymes, microbial fermentation, or exogenous addition of flavor precursors to produce flavored oils, in practice, flavor enhancement still primarily relies on traditional processes. However, these traditional methods still present several unresolved challenges. First, standardizing the flavor of oils is difficult, especially during the roasting process, which requires workers to closely monitor the discharge temperature. Delayed discharge and elevated temperatures can create a burnt smell. Second, traditional roasted seed oil extraction equipment is open, generating fumes that pollute the environment. Third, traditional methods are inefficient in producing flavor, with some flavor compounds dissipated into the air and some lost to the meal rather than fully incorporated into the flavored oil, resulting in significant flavor loss. Fourth, traditionally produced flavored oils are not refined, resulting in high smoke, high acidity, and high peroxide values, resulting in poor quality.

[0005] In summary, existing edible oil processing methods mostly focus on generating flavor compounds, but fail to address the issues of high acid value, high smoke content, high impurities, and low flavor production efficiency associated with flavored oils. Therefore, there is an urgent need to provide a method for producing flavored oils with high flavor production efficiency, high nutrient extraction rates, low acid value, short processing time, low phospholipid content, and reduced smoke. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems of the prior art in flavor oils, such as high acid value and peroxide value, large amount of oil smoke, many harmful substances, large loss of nutrients, low aroma production efficiency, and low nutrient extraction efficiency, and to provide a high-quality special flavor oil and a preparation method thereof. The vegetable oil prepared by the method has high content of nutrients and flavor substances, low content of harmful substances (benzopyrene), low acid value and peroxide value, less oil smoke during cooking, short processing time, high aroma production efficiency and nutrient extraction rate, and the vegetable oil prepared by the method can also have a low phosphorus content without the need for hydration degumming treatment.

[0007] In order to achieve the above object, the present invention provides a first aspect of a method for preparing a flavored vegetable oil, wherein the method comprises the following steps:

[0008] (1) mixing the oil material with the first edible oil and then sequentially performing a first stage heating and a second stage heating under a condition where the oxygen concentration is less than 0.5 v % to obtain a first solid-liquid mixture;

[0009] (2) performing a first solid-liquid separation on the first solid-liquid mixture to obtain a first clear oil and a first oil residue;

[0010] Wherein, the first stage heating is carried out under negative pressure, and the second stage heating is carried out under normal pressure;

[0011] The heating temperature in the first stage is 30-160° C. lower than the heating temperature in the second stage.

[0012] The second aspect of the present invention provides a flavored vegetable oil prepared by the method of the present invention.

[0013] Through the above technical solution, the present invention achieves the following technical effects:

[0014] (1) Compared with traditional small-scale pressing, the method of the present invention reduces the loss of nutrient polyphenols in vegetable oil, increases the extraction efficiency of polyphenols, and shortens the production and processing time. In a preferred embodiment, the content of polyphenols in vegetable oil is as high as 150 mg / kg, and the extraction efficiency of polyphenols can be increased by 5-11 times;

[0015] (2) The method of the present invention can significantly promote the conversion of peroxides into aldehydes and ketones, thereby increasing the flavor content of vegetable oils. At the same time, the method can effectively control the generation of fatty acids, reduce the acid value and peroxide value in vegetable oils, and thus reduce the amount of oil smoke during cooking with vegetable oils. In a preferred embodiment, the flavor content of the prepared vegetable oil is as high as 480 mg / kg, the acid value does not exceed 1.5 mgKOH / g, the peroxide value is less than 0.025 g / 100 g, and the cooking fume volume is reduced by 20%-40%;

[0016] (3) The method of the present invention can reduce the content of harmful substances (such as benzopyrene) in vegetable oil. At the same time, the vegetable oil prepared by the method of the present invention can also reduce the phosphorus content in the vegetable oil without undergoing hydration degumming treatment. In a preferred embodiment, the benzopyrene content in the prepared vegetable oil is less than 1.6 mg / kg and the phosphorus content is less than 2.5 mg / kg. DETAILED DESCRIPTION

[0017] The endpoints of the ranges and any values ​​disclosed herein 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 endpoints of each range, the endpoints of each range and 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 to be specifically disclosed herein.

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

[0019] (1) mixing the oil material with the first edible oil and then sequentially performing a first stage heating and a second stage heating under a condition where the oxygen concentration is less than 0.5 v % to obtain a first solid-liquid mixture;

[0020] (2) performing a first solid-liquid separation on the first solid-liquid mixture to obtain a first clear oil and a first oil residue;

[0021] Wherein, the first stage heating is carried out under negative pressure, and the second stage heating is carried out under normal pressure;

[0022] The heating temperature in the first stage is 30-160° C. lower than the heating temperature in the second stage.

[0023] According to some embodiments of the present invention, the temperature of the first stage heating is 60-110° C.; and the time of the first stage heating is 0.5-2 h.

[0024] Preferably, the temperature of the first stage heating is 100-110° C.; and the time of the first stage heating is 1-1.5 h.

[0025] According to some embodiments of the present invention, the temperature of the second stage heating is 140-220° C.; and the time of the second stage heating is 0.5-3 h.

[0026] Preferably, the temperature of the second stage heating is 145-180° C.; and the time of the second stage heating is 1-2 hours.

[0027] For purposes of this disclosure, the first and second stage heating times refer to the time the mixture of oil and edible oil is heated to the set heating temperature and maintained at that temperature, excluding the time spent heating up and cooling down. For example, if the first stage heating temperature is 100°C, "a heating time of 1 hour" means heating the mixture of oil and edible oil to 100°C and maintaining it at that temperature for 1 hour.

[0028] In the present invention, in order to prevent the oil from sinking to the bottom, resulting in uneven heating of the oil during the heating process, preferably, the first and second stage heating can be carried out in a closed reactor equipped with a stirring paddle, and the speed of the stirring paddle can be adjusted according to actual conditions.

[0029] Preferably, the stirring speed of the first and second stage heating is independently 50-300 rpm; more preferably, the stirring speed of the first stage heating is 150-300 rpm; the stirring speed of the second stage heating is 50-150 rpm.

[0030] According to some embodiments of the present invention, the first stage heating is performed under a vacuum degree ≤ 0.05 MPa.

[0031] In the present invention, the first stage heating is carried out in a sealed container, such as a sealed reactor. In order to make the oxygen concentration in the sealed container lower than the above-mentioned limited range, the oxygen concentration can be reduced by filling the sealed container with nitrogen or carbon dioxide.

[0032] In the present invention, a vacuum device can be used to reduce the pressure in the sealed container so that the sealed container is under negative pressure.

[0033] In the present invention, if the temperature of the first stage heating is lower than the above-defined range (e.g., vacuuming below 60°C), the oil will not be completely dehydrated. If the temperature of the first stage heating is higher than 110°C, flavor substances will be removed, affecting the aroma production effect. Performing the first stage heating under the above-mentioned vacuum conditions and temperature can reduce the loss of flavor substances, more efficiently remove moisture from the oil, and lower the acid value and peroxide value of the vegetable oil.

[0034] According to some embodiments of the present invention, the heating rate of the first stage heating is 60-120° C. / h.

[0035] According to some embodiments of the present invention, the heating rate of the second stage heating is 40-90° C. / h.

[0036] In the present invention, the conditions of the second stage heating meet the above-mentioned limited range, which can further control the generation of fatty acids, reduce the acid value of vegetable oil, and thus reduce the amount of oil smoke when cooking with vegetable oil.

[0037] According to some embodiments of the present invention, the oil is selected from oil seeds and / or oil cakes obtained by pressing oil seeds.

[0038] In the present invention, there is no particular limitation on oilseeds; any seed from which oil can be extracted is suitable for use in the present method. For example, the oilseeds include, but are not limited to, soybeans, peanuts, rapeseed, linseed, sunflower seeds, sesame seeds, tung oil, maple seeds, and evening primrose seeds. In a specific embodiment provided by the present invention, rapeseed, linseed, and peanut are used as the oilseeds to prepare rapeseed oil, peanut oil, and linseed oil, respectively.

[0039] In the present invention, the type of the first edible oil is not particularly limited. Edible vegetable oils obtained by squeezing or leaching oil and performing a certain degree of refining, or animal fats extracted from animals are also suitable for this method. For example, the first edible oil can be a first-grade edible oil or a second-grade edible oil (first-grade edible oil and second-grade edible oil can be purchased from COFCO Fortune Food Marketing Co., Ltd.). Preferably, the first edible oil includes but is not limited to rapeseed oil, peanut oil, soybean oil, linseed oil, sunflower seed oil, and sesame oil. In the specific embodiment provided by the present invention, first-grade rapeseed oil, first-grade linseed oil, and first-grade peanut oil are respectively used as the first edible oil.

[0040] According to some embodiments of the present invention, the mass ratio of the oil material to the first edible oil is (0.05-0.5):1.

[0041] According to some embodiments of the present invention, the first solid-liquid separation method is selected from filtration and / or centrifugation.

[0042] In the present invention, there is no particular limitation on the method of filtration or centrifugation. For example, filtration can be performed using a filter or centrifugation can be performed using a centrifuge. Preferably, the pore size of the filter is 0.2-1 mm; the rotation speed of the centrifuge is 2000-5000 rpm.

[0043] In the present invention, preferably, the method further comprises sequentially crushing and drying the oil before mixing the oil with the edible oil.

[0044] Preferably, the pulverization conditions are such that the particle size of the pulverized oil is no greater than 1.5 mm.

[0045] Preferably, the drying conditions are such that the moisture content of the oil is 3 wt% to 15 wt%.

[0046] In the present invention, in order to further increase the nutrient content of the prepared vegetable oil, the first oil residue obtained by the first solid-liquid separation can be subjected to multiple extractions. Preferably, the method further comprises mixing the first oil residue and the second edible oil in step (2), followed by a first heat treatment and a second solid-liquid separation, to obtain a second oil residue and a second clear oil.

[0047] More preferably, the method further comprises mixing the second oil residue with a third edible oil and then sequentially performing a second heat treatment and a third solid-liquid separation to obtain a third clear oil and a third oil residue.

[0048] Preferably, the mass ratio of the first oil residue to the second edible oil is 1:(1-5); the mass ratio of the second oil residue to the third edible oil is 1:(1-5).

[0049] In the present invention, the types of the second and third edible oils are the same as those of the first edible oil, and are not described in detail herein. The fats and oils used in the first, second and third edible oils can be of the same type or different types.

[0050] Preferably, the conditions of the first and second heat treatments independently include: a temperature of 140-220° C., preferably 145-180° C.; and a time of 0.5-3 h, preferably 1-2 h.

[0051] In the present invention, to prevent the oil residue from settling to the bottom and causing uneven heating of the oil residue during the heat treatment process, the first and second heat treatments are preferably performed in a closed reactor equipped with a stirring paddle, and the stirring paddle speed can be adjusted according to actual conditions. Preferably, the stirring speed of the first and second heat treatments is independently 50-300 rpm.

[0052] Preferably, the second and third solid-liquid separation methods are each independently selected from centrifugation and / or filtration.

[0053] In the present invention, the methods and conditions of the second and third solid-liquid separations are the same as those of the first solid-liquid separation, and will not be described in detail here.

[0054] In the present invention, the first clear oil, the second clear oil, and the third clear oil may be used alone as flavored vegetable oils without being mixed, or they may be mixed at will to prepare a special flavored oil. For example, the first clear oil and the second clear oil may be mixed, or the first clear oil and the third clear oil may be mixed, or the second clear oil and the third clear oil may be mixed, or the first clear oil, the second clear oil, and the third clear oil may be mixed.

[0055] Preferably, the method comprises mixing the first, second and third clear oils to obtain a special flavor oil.

[0056] Preferably, the mass ratio of the first, second and third clear oils is 1:(0.1-1):(0.1-1).

[0057] The second aspect of the present invention provides flavored vegetable oil prepared by the method of the present invention.

[0058] According to a particularly preferred embodiment of the present invention, a method for preparing flavored rapeseed oil is provided, the method comprising the following steps:

[0059] (1) cleaning and removing impurities (removing stones, dirt, and moldy materials) rapeseed in a grinder, and crushing the crushed rapeseed powder (water content of about 10 wt%) to a particle size of less than 0.5 mm;

[0060] (2) drying the rapeseed meal in an oven, wherein the moisture content of the dried rapeseed meal is 5-8 wt %;

[0061] (3) transferring the dried rapeseed meal and the first-grade rapeseed oil into a sealed container (sealed reactor), filling the sealed container with nitrogen so that the oxygen concentration is less than 0.5v%; using a vacuum pump to maintain the vacuum degree in the sealed container below 0.03MPa; heating the mixture of rapeseed meal and first-grade rapeseed oil to 80-95°C at a heating rate of 60-75°C / h, and heating at this temperature for 1.2-1.5h;

[0062] The mass ratio of the dried rapeseed meal to the first-grade rapeseed oil is 1:(3-3.5);

[0063] (4) transferring the heated mixture in step (3) into a sealed reactor equipped with a stirring paddle via a pump, and filling the sealed reactor with nitrogen so that the oxygen concentration is less than 0.5% by volume; heating the mixture to 170-180° C. at a heating rate of 70-90° C. / h under normal pressure, and heating at this temperature for 1-1.5 hours with a stirring speed of 100-150 rpm; obtaining a first solid-liquid mixture after the heating is completed; filtering the first solid-liquid mixture (the pore size of the filter is 0.1-0.2 mm) to obtain a first clear oil and a first oil residue;

[0064] (5) transferring the first oil residue and the first-grade rapeseed oil to a sealed reactor equipped with a stirring paddle, heating and solid-liquid separation according to the method of step (4) to obtain a second clear oil and a second oil residue;

[0065] The mass ratio of the first oil residue to the first-grade rapeseed oil is 1:(2-2.5);

[0066] (6) transferring the second oil residue and the first-grade rapeseed oil to a sealed reactor equipped with a stirring paddle, heating and solid-liquid separation according to the method of step (4) to obtain a third clear oil and a third oil residue;

[0067] The mass ratio of the second oil residue to the first-grade rapeseed oil is 1:(2-2.5);

[0068] (7) The first, second and third clear oils are mixed in a mass ratio of 1:(0.5-1):(0.5-1) to obtain a special flavor rapeseed oil.

[0069] The present invention also relates to the application of the above method in increasing / improving the acid value (mgKOH / g), peroxide value (g / 100g), oil smoke volume, phosphorus content (mg / kg), and benzopyrene content (mg / kg) of vegetable oil.

[0070] The present invention will be described in detail below through examples.

[0071] First-grade rapeseed oil was purchased from COFCO Fortune Food Marketing Co., Ltd., and the product model was first-grade pressed.

[0072] First-grade linseed oil was purchased from COFCO Fortune Food Marketing Co., Ltd., and the product model was first-grade pressed.

[0073] First-grade peanut oil was purchased from COFCO Fortune Food Marketing Co., Ltd., and the product model was first-grade pressed.

[0074] The crusher was purchased from IKA, and the product model is Basic S025.

[0075] Example 1

[0076] Preparation of flavored rapeseed oil using rapeseed as raw material;

[0077] (1) cleaning and removing impurities (removing stones, dirt, and moldy materials) rapeseed in a grinder, and crushing the crushed rapeseed powder (water content of about 10 wt%) to a particle size of less than 0.5 mm;

[0078] (2) drying the rapeseed powder in an oven, wherein the moisture content of the dried rapeseed powder is 8 wt %;

[0079] (3) 1 kg of dried rapeseed powder and 3 kg of first-grade rapeseed oil were transferred to a sealed container (sealed reactor), nitrogen was filled into the sealed container to make the oxygen concentration less than 0.5 v%; the vacuum degree in the sealed container was made to 0.02 MPa using a vacuum pump; the mixture of rapeseed powder and first-grade rapeseed oil was heated to 80°C at a heating rate of 60°C / h and heated at this temperature for 1.5 h;

[0080] (4) The mixture heated in step (3) is transferred into a sealed reactor equipped with a stirring paddle via a pump, and nitrogen is filled into the sealed reactor to make the oxygen concentration less than 0.5% by volume; the mixture is heated to 170°C at a heating rate of 90°C / h under normal pressure, and heated at this temperature for 1 hour with a stirring speed of 100 rpm; after the heating is completed, a first solid-liquid mixture is obtained; the first solid-liquid mixture is filtered (the pore size of the filter is 0.1 mm) to obtain a first clear oil and a first oil residue;

[0081] (5) transferring 1.5 kg of the first oil residue and 2.5 kg of first-grade rapeseed oil to a sealed reactor equipped with a stirring paddle, heating and solid-liquid separation were performed according to the method of step (4) to obtain a second clear oil and a second oil residue;

[0082] (6) transferring 1.5 kg of the second oil residue and 2.5 kg of the first-grade rapeseed oil to a sealed reactor equipped with a stirring paddle, and performing heating and solid-liquid separation according to the method of step (4) to obtain a third clear oil and a third oil residue;

[0083] (7) The first, second and third clear oils are mixed in a mass ratio of 1:1:1 to obtain a special flavor rapeseed oil.

[0084] Example 2

[0085] Flavored linseed oil is prepared from linseed as raw material;

[0086] (1) Cleaning and removing impurities (removing stones, dirt, and moldy materials) flax seeds in a grinder to obtain flax seed powder (with a water content of about 10 wt%) with a particle size of less than 1 mm;

[0087] (2) drying the flaxseed meal in an oven, wherein the moisture content of the rapeseed meal after drying is 5 wt %;

[0088] (3) 1 kg of dried flaxseed meal and 4 kg of first-grade linseed oil were transferred to a sealed container (sealed reactor), nitrogen was filled into the sealed container to make the oxygen concentration less than 0.5 v %; the vacuum degree in the sealed container was set to 0.04 MPa using a vacuum pump; the mixture of flaxseed meal and first-grade linseed oil was heated to 100°C at a heating rate of 80°C / h and heated at this temperature for 1 h;

[0089] (4) The mixture heated in step (3) is transferred into a sealed reactor equipped with a stirring paddle via a pump, and nitrogen is filled into the sealed reactor to make the oxygen concentration less than 0.5% by volume; the mixture is heated to 170°C at a heating rate of 60°C / h under normal pressure, and heated at this temperature for 1 hour with a stirring speed of 200 rpm; after the heating is completed, a first solid-liquid mixture is obtained; the first solid-liquid mixture is filtered (the pore size of the filter is 0.2 mm) to obtain a first clear oil and a first oil residue;

[0090] (5) transferring 1 kg of the first oil residue and 3.5 kg of first-grade linseed oil to a sealed reactor equipped with a stirring paddle, heating and solid-liquid separation were performed according to the method and conditions of step (4) to obtain a second clear oil and a second oil residue;

[0091] (6) 1 kg of the second oil residue and 3.5 kg of the first-grade linseed oil were transferred to a sealed reactor equipped with a stirring paddle, and heated and solid-liquid separated according to the method and conditions of step (4) to obtain a third clear oil and a third oil residue.

[0092] (7) The first, second and third clear oils are mixed in a mass ratio of 1:1:1 to obtain a special flavor linseed oil.

[0093] Example 3

[0094] Flavored peanut oil is prepared from peanut seeds;

[0095] (1) Peanut seeds that have been cleaned and free of impurities (stones, dirt, and moldy materials) are crushed in a crusher to obtain peanut powder (with a water content of about 10 wt%) with a particle size of less than 0.8 mm;

[0096] (2) drying the peanut powder in an oven, wherein the moisture content of the dried peanut powder is 5 wt %;

[0097] (3) 1 kg of dried peanut powder and 3 kg of first-grade peanut oil were transferred to a sealed container (sealed reactor), nitrogen was filled into the sealed container to make the oxygen concentration less than 0.5 v%; the vacuum degree in the sealed container was set to 0.03 MPa using a vacuum pump; the mixture of peanut powder and first-grade peanut oil was heated to 100 °C at a heating rate of 80 °C / h and heated at this temperature for 1 h;

[0098] (4) The mixture heated in step (3) is transferred into a sealed reactor equipped with a stirring paddle via a pump, and nitrogen is filled into the sealed reactor to make the oxygen concentration less than 0.5% by volume; the mixture is heated to 150° C. at a heating rate of 60° C. / h under normal pressure, and heated at this temperature for 1 h with a stirring speed of 200 rpm; after the heating is completed, a first solid-liquid mixture is obtained; the first solid-liquid mixture is filtered (the pore size of the filter is 0.1 mm) to obtain a first clear oil and a first oil residue;

[0099] (5) transferring 1.5 kg of the first oil residue and 2.5 kg of first-grade peanut oil to a sealed reactor equipped with a stirring paddle, heating and solid-liquid separation were performed according to the method and conditions of step (4) to obtain a second clear oil and a second oil residue;

[0100] (6) 1.5 kg of the second oil residue and 2.5 kg of the first-grade peanut oil were transferred to a sealed reactor equipped with a stirring paddle, and heated and solid-liquid separated according to the method and conditions of step (4) to obtain a third clear oil and a third oil residue.

[0101] (7) The first, second and third clear oils are mixed in a mass ratio of 1:1:1 to obtain a special flavor peanut oil.

[0102] Example 4

[0103] The method of Example 1 is followed, except that the heating temperature in step (3) (first stage heating temperature) is 40° C., and the other operating procedures and process parameters are the same as those of Example 1.

[0104] Example 5

[0105] The method of Example 1 is followed, except that the heating temperature in step (4) (second stage heating temperature) is 130° C., and the other operating procedures and process parameters are the same as those of Example 1.

[0106] Example 6

[0107] The method of Example 1 is followed, except that the heating rate in step (3) (the heating rate in the first stage of heating) is 20°C / h, and the other operating procedures and process parameters are the same as those of Example 1.

[0108] Example 7

[0109] The method of Example 1 is followed, except that the heating rate in step (4) (the heating rate of the second stage heating) is 10°C / h, and the other operating procedures and process parameters are the same as those of Example 1.

[0110] Comparative Example 1

[0111] Rapeseed oil is prepared using a traditional small-scale pressing process. Specifically, the preparation method includes: placing the rapeseed that has been cleaned and removed of impurities (stones, soil, and moldy materials) into a gas-fired or electrically heated drum seed frying pan with a bottom temperature of 450±50°C; after the rapeseed contacts the inner wall of the frying pan, the surface temperature gradually rises, and an infrared temperature measuring gun is used to measure the surface temperature of the rapeseed. When the temperature rises to 157.5±2°C, the frying pan is rotated in reverse to start the unloading mode; the unloaded rapeseed is directly transferred to the hopper of the oil press, and the rapeseed is pushed and transported by the screw of the oil press into the interior of the press chamber. Under the push of the screw, the rapeseed is subjected to a huge extrusion force, the rapeseed structure is broken, and the oil overflows from the rapeseed, and the overflowed oil overflows from the small channels on the wall of the pressing chamber to obtain small-scale crude oil.

[0112] The crude oil contains a small amount of solid rapeseed powder, which needs to be removed by centrifugation or filtration. After the crude oil is free of solid impurities, salt water (the concentration of the salt water is 10wt%, and the amount of the salt water is 1.5wt% of the weight of the oil) and diatomaceous earth (1wt% of the weight of the oil) are added and mixed and stirred. After uniform stirring, phospholipids and other components in the crude oil form an emulsified colloid under the action of the salt water. After plate and frame filtration, the colloid is intercepted by the diatomaceous earth, thereby achieving the purpose of separating the colloid and impurities. After the colloid and impurities are removed, the phosphorus content in the crude oil is reduced from about 400mg / kg to below 20mg / kg, thereby obtaining traditional small-pressed fragrant rapeseed oil.

[0113] Comparative Example 2

[0114] Linseed oil is prepared using a traditional small-scale pressing process. Specifically, the preparation method includes: placing cleaned linseed (removing stones, dirt, and moldy materials) into a gas-fired or electrically heated drum seed roasting pan with a bottom temperature of 450±50°C; after the linseed contacts the inner wall of the pan, the surface temperature gradually rises, and an infrared temperature measuring gun is used to measure the surface temperature of the linseed. When the temperature rises to 192.5±7.5°C, the pan is rotated in the opposite direction to start a discharge mode; the discharged linseed is directly transferred to a hopper of an oil press, and the linseed is pushed and transported by a screw of the oil press into a chamber of the press. Under the action of the screw, the linseed is subjected to a huge squeezing force, which causes the linseed structure to break, and oil to overflow from the linseed. The overflowed oil overflows from small channels on the wall of the press chamber to obtain small-scale crude oil.

[0115] The crude oil contains a small amount of solid linseed powder, which needs to be removed by centrifugation or filtration. After the crude oil is free of solid impurities, salt water (the concentration of the salt water is 10 wt%, and the amount of the salt water is 1.5 wt% of the weight of the oil) and diatomaceous earth (1 wt% of the weight of the oil) are added and mixed and stirred. After uniform stirring, phospholipids and other components in the crude oil form an emulsified colloid under the action of the salt water. After plate and frame filtration, the colloid is intercepted by the diatomaceous earth, achieving the purpose of separating the colloid and impurities. After the colloid is removed, the phosphorus content in the crude oil is reduced from about 400 mg / kg to below 20 mg / kg, thereby obtaining traditional small-pressed rich-flavor linseed oil.

[0116] Comparative Example 3

[0117] Peanut oil is produced using a traditional small-scale pressing process. Specifically, the preparation method includes placing cleaned peanut kernels (removing stones, dirt, and moldy materials) into a gas-fired or electrically heated drum-type seed roaster at a bottom temperature of 450±50°C. As the peanut kernels contact the inner wall of the wok, their surface temperature gradually rises. This temperature is measured using an infrared thermometer. When the temperature reaches 160±10°C, the wok is reversed to initiate unloading. The unloaded peanut kernels are then directly transferred to the hopper of an oil press. The screw of the oil press propels the kernels into the chamber, where they are subjected to tremendous pressure, causing the kernel structure to break and oil to escape from the kernels. The excess oil then flows through small channels in the chamber wall, producing small-scale crude oil.

[0118] The crude oil contains a small amount of solid peanut kernel powder, which needs to be removed by centrifugation or filtration. After the crude oil is free of solid impurities, salt water (the concentration of the salt water is 10wt%, and the amount of the salt water is 1.5wt% of the weight of the oil) and diatomaceous earth (1wt% of the weight of the oil) are added and mixed and stirred. After uniform stirring, phospholipids and other components in the crude oil form an emulsified colloid under the action of the salt water. After plate and frame filtration, the colloid is intercepted by the diatomaceous earth, thereby achieving the purpose of separating the colloid impurities. After the colloid impurities are removed, the phosphorus content in the crude oil is reduced from about 400mg / kg to below 20mg / kg, thereby obtaining traditional small-pressed fragrant peanut oil.

[0119] Comparative Example 4

[0120] The method of Example 1 is followed, except that the heating in step (3) is carried out under normal pressure, and the other operating procedures and process parameters are the same as those of Example 1.

[0121] Comparative Example 5

[0122] The method of Example 1 was followed, except that the heating in step (4) was carried out under negative pressure (the vacuum degree in the sealed reactor was 0.03 MPa), and the other operating procedures and process parameters were the same as those in Example 1.

[0123] Comparative Example 6

[0124] The method of Example 1 is followed, except that the heating in step (3) is carried out under normal pressure; the heating in step (4) is carried out under negative pressure (the vacuum degree in the sealed reactor is 0.03 MPa), and the other operating procedures and process parameters are the same as those in Example 1.

[0125] Comparative Example 7

[0126] The method of Example 1 is followed, except that the heating temperature in step (3) is 10°C lower than the heating temperature in step (4). Specifically, the heating temperature in step (3) is 130°C, and the heating temperature in step (4) is 140°C. Other operating procedures and process parameters are the same as those in Example 1.

[0127] Comparative Example 8

[0128] The method of Example 1 is followed, except that the first-stage rapeseed oil is first heated, and then the heated first-stage rapeseed oil is mixed with rapeseed powder for second-stage heating. Specifically, the first-stage rapeseed oil is heated to 80° C. according to the method of step (3) of Example 1, and then the heated first-stage rapeseed oil is mixed with rapeseed powder. The mixture (a mixture of rapeseed powder and first-stage rapeseed oil) is heated in the second stage according to the method of step (4) of Example 1. Other operating procedures and process parameters are the same as those of Example 1.

[0129] Test Case

[0130] The acid value, peroxide value, moisture content, oil smoke content, phosphorus content, benzopyrene, polyphenol and flavor substance content of the flavor oils prepared in the examples and comparative examples were tested respectively; and the nutrient extraction efficiency and flavor substance extraction efficiency and production processing time of the flavor oils prepared in the examples and comparative examples were calculated. The results are shown in Table 1.

[0131] The acid value of flavor oil is determined by the method of "GB 5009.229-2025 National Food Safety Standard Determination of Acid Value in Food".

[0132] The peroxide value of flavor oil is determined by the method of "GB 5009.227-2023 National Food Safety Standard Determination of Peroxide Value in Food".

[0133] The moisture content of flavor oil was determined using the method of "GB 5009.236-2016 National Food Safety Standard - Determination of Moisture and Volatile Matter in Animal and Vegetable Fats and Oils - Method 2".

[0134] The amount of flavor oil smoke was measured using an online oil smoke analyzer (OSEN-100). The specific measurement method includes: taking 20g of flavor oil and placing it in an iron pot to start heating. The iron pot and induction cooker are placed in a sealed cover; the top of the sealed cover is connected to the online oil smoke analyzer through a pipe. The online oil smoke analyzer can record the total particulate matter content in the oil smoke generated by heating (total particulate matter content includes PM10+PM5+PM2.5+PM1). The oil smoke collection time is 3 minutes, and the unit of oil smoke volume is particulate matter concentration mg / m 3 .

[0135] The phosphorus content of flavor oil is determined by the method of "GB / T 5537-2008 Inspection of grains and oils - Determination of phospholipid content".

[0136] The benzopyrene content of flavor oil was determined by the method of "GB 5009.27-2016 National Food Safety Standard Determination of Benzo(a)pyrene in Food".

[0137] The polyphenol content of flavor oil was determined by the LS / T 6119-2017 Grain and Oil Inspection-Determination of Polyphenols in Vegetable Oils-Spectrophotometric Method.

[0138] The flavor compounds (flavor compound content expressed as total volatile compounds) in the flavor oils were determined using GC-MS. The specific method involved equilibrating the headspace vial in a 60°C heating bath for 20 minutes. An activated extraction tip was inserted into the headspace vial to adsorb volatile compounds for 30 minutes, followed by insertion into the GC inlet and thermal desorption for 5 minutes. The inlet temperature was 250°C.

[0139] GC conditions: DB-Wax polar column (30 m × 0.25 mm, 0.25 μm); carrier gas: high-purity helium (purity > 99.99%); flow rate: 1.2 mL / min; splitless mode; heating program: column temperature: starting temperature 45°C, heated to 180°C at a rate of 4°C / min, held for 2 min, then heated to 230°C at a rate of 10°C / min, held for 6 min.

[0140] MS conditions were as follows: transfer line temperature 230 °C, electron energy 70 eV, electron ionization source temperature 250 °C, quadrupole temperature 150 °C, mass scan range 40–500 m / z, and full scan mode.

[0141] All indexes were measured three times. By searching the NIST14 spectral library, compounds with positive and negative matching scores greater than 800 (maximum 1000) were selected and qualitatively analyzed in combination with the retention index (RI). The relative content of flavor substances was calculated according to formula (I).

[0142] C j =C i*A j / A i (I)

[0143] In formula (I): C j is the mass concentration of flavor substances, mg / kg.

[0144] C i is the mass concentration of the internal standard, mg / mL.

[0145] A j is the peak area of ​​flavor substances.

[0146] A i is the peak area of ​​the internal standard.

[0147] Nutrient extraction efficiency (nutrients calculated as polyphenols) = nutrient extraction amount / oil mass, where nutrient extraction amount = amount of special fragrance oil * polyphenol concentration in strong fragrance oil.

[0148] Flavor substance extraction efficiency = flavor substance extraction amount / oil mass, where flavor substance extraction amount = amount of strong-flavor oil x flavor substance concentration in special-flavor oil.

[0149] Table 1

[0150]

[0151]

[0152] Table 1 (continued)

[0153]

[0154] As can be seen from the data in Table 1, by comparing Examples 1-3 with Examples 4-7, it can be seen that the vegetable oil prepared by the preferred method has a high content of nutrients and flavor substances, less harmful substances (benzopyrene), low acid value and peroxide value, less oil smoke during cooking, short processing time, high aroma production efficiency and nutrient extraction rate. In addition, the vegetable oil prepared by this method does not require hydration degumming treatment and can also make the phosphorus content in the vegetable oil very low.

[0155] Compared with the examples, the vegetable oils prepared in comparative examples 1-3 using traditional pressing processes have low extraction efficiency of nutrients and flavor substances, high content of harmful substances (benzopyrene), high acid value and peroxide value, large amount of oil smoke during cooking, and long processing time. In addition, the phosphorus content in the vegetable oils prepared in comparative examples 1-3 is still relatively high after hydration degumming treatment.

[0156] Compared with the embodiments, the first and second stage heating of Comparative Example 4 are both carried out under normal pressure, resulting in the prepared vegetable oil having high moisture content, high phosphorus content, high acid value, and large amount of oil smoke during cooking; in Comparative Example 5, the first and second stage heating are both carried out under negative pressure, resulting in the prepared vegetable oil having high phosphorus content, low flavor substance content, and low flavor substance extraction efficiency; in Comparative Example 6, the first stage heating is carried out under normal pressure, while the second stage heating is carried out under negative pressure, resulting in the prepared vegetable oil having high acid value, large amount of oil smoke during cooking, low flavor substance content, and low flavor substance extraction efficiency; in Comparative Example 7, the temperature of the first stage heating is too high, and the temperature difference between the first stage heating temperature and the second stage heating temperature does not meet the requirements, resulting in the prepared vegetable oil having high phosphorus content, low flavor substance content, and low flavor substance extraction efficiency; in Comparative Example 8, the edible oil is preheated (first stage heating) and then mixed with the oil for second stage heating, resulting in the prepared vegetable oil having high moisture content, high phosphorus content, high acid value, and large amount of oil smoke during cooking.

[0157] In summary, the vegetable oil prepared by the method of the present invention has good physical and chemical quality (low acid value, low peroxide value, low phosphorus content, low oil moisture), high nutrient extraction efficiency, more complete aroma, short processing time and less cooking fume.

[0158] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing flavored vegetable oil, characterized in that: The method comprises the following steps: (1) mixing the oil material with the first edible oil and then sequentially performing a first stage heating and a second stage heating under a condition where the oxygen concentration is less than 0.5 v % to obtain a first solid-liquid mixture; (2) performing a first solid-liquid separation on the first solid-liquid mixture to obtain a first clear oil and a first oil residue; Wherein, the first stage heating is carried out under negative pressure, and the second stage heating is carried out under normal pressure; The heating temperature in the first stage is 30-160° C. lower than the heating temperature in the second stage.

2. The method according to claim 1, wherein The heating temperature in the first stage is 60-110° C., preferably 100-110° C.; the heating time in the first stage is 0.5-2 h, preferably 1-1.5 h; And / or, the heating temperature in the second stage is 140-220° C., preferably 145-180° C.; the heating time in the second stage is 0.5-3 h, preferably 1-2 h; And / or, the first stage heating is performed under a vacuum degree ≤ 0.05 MPa.

3. The method according to claim 1 or 2, wherein: The heating rate of the first stage heating is 60-120°C / h; And / or, the heating rate of the second stage heating is 40-90° C. / h.

4. The method according to any one of claims 1 to 3, wherein: The oilseed is selected from oilseeds and / or oilseed cakes; Preferably, the oilseeds are selected from at least one of soybeans, peanuts, rapeseeds, linseeds, sunflower seeds, tung seeds, maple seeds, evening primrose seeds and sesame seeds; Preferably, the first edible oil is at least one selected from rapeseed oil, peanut oil, soybean oil, linseed oil, sunflower oil and sesame oil.

5. The method according to any one of claims 1 to 4, wherein: The mass ratio of the oil material to the first edible oil is (0.05-0.5):1; And / or, the first solid-liquid separation method is selected from filtration and / or centrifugation.

6. The method according to any one of claims 1 to 5, wherein: The method further comprises, before mixing the oil with the edible oil, sequentially crushing and drying the oil; Preferably, the crushing conditions are such that the particle size of the crushed oil material is no greater than 1.5 mm; Preferably, the drying conditions are such that the moisture content of the oil is 3 wt% to 15 wt%.

7. The method according to any one of claims 1 to 6, wherein: The method further comprises mixing the first oil residue and the second edible oil in step (2) and then sequentially performing a first heat treatment and a second solid-liquid separation to obtain a second oil residue and a second clear oil; Preferably, the method further comprises mixing the second oil residue with a third edible oil and then sequentially performing a second heat treatment and a third solid-liquid separation to obtain a third clear oil and a third oil residue.

8. The method according to claim 7, wherein: The mass ratio of the first oil residue to the second edible oil is 1:(1-5); the mass ratio of the second oil residue to the third edible oil is 1:(1-5); and / or, the second and third edible oils are each independently selected from at least one of rapeseed oil, peanut oil, soybean oil, linseed oil, sunflower oil and sesame oil; And / or, the conditions of the first and second heat treatments independently include: temperature of 140-220°C, preferably 145-180°C; time of 0.5-3h, preferably 1-2h; stirring speed of 300-600rpm; And / or, the second and third solid-liquid separation methods are each independently selected from centrifugation and / or filtration.

9. The method according to claim 8, wherein The method further comprises mixing the first, second and third clear oils to obtain a special flavor oil; Preferably, the mass ratio of the first, second and third clear oils is 1:(0.1-1):(0.1-1).

10. The flavored vegetable oil prepared by the method according to any one of claims 1 to 9.

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