Preparation method of camellia oleosa seed oil with rich flavor and safety

Abstract

The invention discloses a preparation method of safe camellia oleosa seed oil with rich flavor, which comprises the following steps: 1) extracting freshly squeezed camellia oleosa seed oil to obtain squeezed camellia oleosa seed oil and tea seed cake meal; (2) extruding and puffing to obtain puffed tea seed meal powder; 3) pretreatment of glycerol and catechin: adding glycerol and catechin into the puffed tea seed meal powder, magnetically stirring, and fully and uniformly mixing to obtain a tea seed meal powder mixture; 4) performing ultrahigh pressure treatment: uniformly mixing the tea seed meal powder mixture with the squeezed camellia oleosa seed oil, and performing ultrahigh pressure treatment at the pressure of 800-900 MPa and the temperature of 40-50 DEG C for 2-3 minutes to obtain a meal oil mixture; 5) filtering to obtain mixed oil; and 6) adding water and centrifuging: adding water into the mixed oil, centrifuging, and taking the upper oil phase to obtain the finished product camellia oleosa seed oil which is rich in flavor and safe. According to the method, the comprehensive utilization rate of the tea seed cake meal can be effectively increased, the content of furfural and 5-hydroxymethylfurfural in the camellia oleosa seed oil can be effectively reduced, and the camellia oleosa seed oil can be endowed with very strong flavor.

Description

Technical Field

[0001] The invention relates to the technical field of edible oil processing, and in particular to a method for preparing camellia oil with strong flavor and safety. Background Art

[0002] Camellia seed oil is a woody plant edible oil with high nutritional value and certain health functions. It is very similar to olive oil in physical and chemical properties. Its composition is unsaturated fatty acids mainly composed of oleic acid and linoleic acid, with a content of more than 90%, and does not contain components such as erucic acid that are difficult to digest and absorb.

[0003] Tea seed cake is a by-product of the preparation of camellia oil, which contains cellulose, protein, sugar and other ingredients. In order to improve the comprehensive utilization of such by-products, reduce the waste of tea seed cake resources, and obtain camellia oil with a strong flavor, the tea seed cake is usually further processed by pressing. For example, patent application number CN201510147338.4 discloses a strong-flavored, healthy and safe camellia oil and a preparation method thereof, which includes the following steps: 1. Preparing tea seed kernels: taking fresh tea seeds, drying them in the sun, washing them, shelling them, selecting and removing impurities, and ripening them; 2. Primary pressing: feeding the ripened tea seed kernels into an oil press for pressing; 3. Preparing strong-flavored, healthy and safe camellia oil: crushing tea dregs into blocks, and filtering the camellia oil obtained by traditional pressing to obtain an oil cake; adding camellia oil to the tea dregs to obtain a dregs-oil mixture, wherein the dregs-oil ratio is such that the dregs-oil mixture contains 15% to 30% by weight of camellia oil; mixing the dregs-oil mixture with the oil cake to obtain a dregs-oil cake mixture, wherein the dregs-oil cake ratio is such that the dregs-oil mixture contains 50% to 80% by weight; and putting the mixture into the preheated press for pressing.

[0004] This method uses the method of secondary pressing of tea dregs, so that the aroma substances produced by the Maillard reaction in the secondary pressing process are taken out together with the camellia oil to prepare camellia oil with strong flavor. However, the pressing temperature is relatively high. During the Maillard reaction, not only volatile flavor substances such as alcohols and ketones are generated, but also furfural and 5-hydroxymethylfurfural are generated. However, furfural is a chemical substance with moderate toxicity, which can enter the human body through ingestion and cause acute poisoning. 5-Hydroxymethylfurfural is irritating to the eyes, mucous membranes, and skin, and has neurotoxicity and genotoxicity. It can be metabolized into 5-sulfinylmethylfurfural in the body, which has strong carcinogenicity and genotoxicity (Research Progress on the Production Mechanism, Content Detection and Safety Evaluation of Furfural and 5-Hydroxymethylfurfural in Food, Zhang Yuyu, 2012).

[0005] In order to reduce the harm of furfural and 5-hydroxymethylfurfural to the human body and improve the safety of edible products, there are studies in the prior art that use ultra-high pressure technology to reduce 5-hydroxymethylfurfural. For example, patent application number CN201911101683.9 discloses a method for preparing low-temperature combined ultra-high pressure sterilized milk that reduces thermal processing by-products, including: 1) low-temperature pretreatment: the raw milk is kept at 50°C for 10-20 minutes after milk purification, and homogenized at 15-20MPa; 2) canning: the pretreated raw milk is filled in a sterile food-grade PET bottle; 3) ultra-high pressure sterilization: the canned milk is placed in an ultra-high pressure device and treated at 500-600MPa for 10-15 minutes to obtain sterilized milk with reduced thermal processing by-products. This method uses low temperature combined with static ultra-high pressure treatment, which can effectively reduce and control the thermal processing by-products produced in traditional thermal processing liquid milk, including furosine, 5-hydroxymethylfurfural, carboxymethyllysine and carboxyethyllysine, and improve the quality and safety of liquid milk.

[0006] At present, in the field of edible oil production technology, there is no technology that applies ultra-high pressure technology to tea seed cake processing; and when the inventors applied ultra-high pressure technology to tea seed cake processing, it was found that with the increase of ultra-high pressure processing pressure, although the contents of furfural and 5-hydroxymethylfurfural showed a downward trend below 600Mpa, the flavor of the tea seed oil prepared at this time was poor; and when the pressure continued to increase, although the flavor could be improved, the content of furfural and 5-hydroxymethylfurfural would continue to increase significantly due to the increase in the degree of Maillard reaction, resulting in a significant decrease in the safety of the tea seed oil.

[0007] Therefore, how to provide a preparation method that can not only improve the comprehensive utilization rate of tea seed cake, but also effectively inhibit the production of furfural and 5-hydroxymethylfurfural in the Maillard reaction of camellia oil, ensure the production safety of camellia oil, and at the same time give camellia oil a rich flavor, has become a technical problem that needs to be solved urgently. Summary of the invention

[0008] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and provide a method for preparing camellia oil with a strong flavor and safety, which can effectively improve the comprehensive utilization rate of camellia cake, effectively reduce the content of furfural and 5-hydroxymethylfurfural in camellia oil, and give camellia oil a very strong flavor.

[0009] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing camellia oil with strong flavor and safety, comprising the following steps:

[0010] 1) Extraction of freshly pressed camellia oil: extracting camellia oil from camellia seeds by pressing to obtain pressed camellia oil and camellia cake;

[0011] 2) Extrusion and puffing: firstly, the tea seed cake is subjected to extrusion and puffing treatment, and then crushed to obtain puffed tea seed cake powder;

[0012] 3) Pretreatment of glycerol and catechins: adding glycerol and catechins to the expanded tea dregs powder, stirring with a magnetic stirrer, and mixing thoroughly to obtain a tea dregs powder mixture;

[0013] 4) Ultrahigh pressure treatment: the tea meal powder mixture and the pressed tea seed oil are mixed evenly and then subjected to ultrahigh pressure treatment, the pressure of the ultrahigh pressure treatment is 800-900 MPa, the temperature is 40-50° C., and the time is 2-3 min to obtain a meal oil mixture;

[0014] 5) filtering to obtain a mixed oil;

[0015] 6) Add water and centrifuge: Add water to the mixed oil, centrifuge, take the upper oil phase, and obtain a finished camellia oil with a strong flavor and safety.

[0016] Furthermore, the step 1) extracting fresh camellia seed oil comprises the following operating steps: a) removing impurities from fresh fruit; b) kneading and crushing; c) sorting seed shells; d) color sorting; e) drying; f) removing impurities; g) shelling; h) pressing oil; and i) filtering.

[0017] Furthermore, the screw speed during extrusion puffing in step 2 is 180-300 r / min, and the puffing temperature is 60-80°C.

[0018] Furthermore, in step 3), the solid-liquid ratio of the puffed tea dregs powder to glycerol is 1:(10-20), and the mass ratio of the puffed tea dregs powder to catechins is 1:(0.006-0.01).

[0019] Preferably, the solid-liquid ratio of the puffed tea seed cake powder to glycerol is 1:15, and the mass ratio of the puffed tea seed cake powder to catechins is 1:0.006.

[0020] Furthermore, in step 3), the temperature during magnetic stirring is 50-80° C., and the stirring time is 1-2 h.

[0021] Furthermore, in the step 4), the mass ratio of the tea dregs powder mixture to the pressed tea seed oil is 1:(10-20).

[0022] Preferably, in step 4), the ultra-high pressure treatment is performed at a pressure of 850 MPa, a temperature of 45° C., and a time of 2.5 min.

[0023] Furthermore, the specific operation steps of step 6) are: adding distilled water to the mixed oil at a volume ratio of 1:1, mixing thoroughly, dissolving glycerol in the distilled water, centrifuging, taking the upper oil phase, and obtaining the finished camellia oil.

[0024] Furthermore, the centrifugal speed is 8000r / min-12000r / min, and the time is 5-8min.

[0025] The beneficial effects of the method for preparing the camellia oil with strong flavor and safety of the present invention are as follows:

[0026] (1) The preparation process of the present invention is simple. After extrusion and puffing, glycerol treatment is used to further improve the cleavage of cellulose and the activity of cellulase in tea seed cake, thereby improving the degree of cellulose degradation and greatly increasing the content of reducing sugars. This can provide more reaction substrates (reducing sugars) for the Maillard reaction during subsequent ultrahigh pressure treatment, so that the Maillard reaction generates more flavor substances. In addition, the addition of glycerol can effectively bring out the flavor substances in the tea seed cake, thereby improving the flavor of tea seed oil.

[0027] (2) During the ultra-high pressure treatment process, the present invention can effectively inhibit the generation of furfural and 5-hydroxymethylfurfural in the Maillard reaction under ultra-high pressure conditions due to the presence of glycerol and catechins in the raw materials. Under the synergistic effect of glycerol and catechins, the rate of generating furfural and 5-hydroxymethylfurfural due to the Maillard reaction during the ultra-high pressure treatment is reduced, thereby greatly reducing the content of furfural and 5-hydroxymethylfurfural in the camellia oil, and also ensuring that the camellia oil has a very strong flavor, greatly reducing the pressure required for obtaining a camellia oil with a very strong flavor during ultra-high pressure treatment, and also improving the safety of the camellia oil;

[0028] (3) The acid value of the camellia oil prepared by the method of the present invention is controlled at 0.1-1.0 mgKOH / g, and the peroxide value is 0.01-0.02 g / 100 g, which meets the first-grade pressing standard of camellia oil GB / T 11765-2018. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 — is a process flow chart of the present invention;

[0030] Figure 2 — is a trend diagram showing the effect of ultra-high pressure treatment pressure on the furfural content in camellia oil;

[0031] Figure 3 — is a trend diagram showing the effect of ultra-high pressure treatment pressure on the content of 5-hydroxymethylfurfural in camellia oil;

[0032] Figure 4 — is a trend chart showing the effect of ultra-high pressure treatment pressure on the flavor of camellia oil. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and examples, but these specific implementation schemes do not limit the protection scope of the present invention in any way.

[0034] Example 1

[0035] A method for preparing camellia oil with strong flavor and safety, the process flow chart of which is as follows Figure 1 As shown, the following steps are included:

[0036] 1) Extraction of freshly pressed camellia oil: extracting camellia oil from camellia seeds by pressing to obtain pressed camellia oil and camellia cake, specifically comprising the following steps: a) removing impurities from fresh fruit: removing dirt, stones, leaves, tree trunks and other impurities to obtain clean camellia seeds; b) kneading and crushing: adopting an extrusion kneading method, controlling the kneading machine speed to 130r / min; c) seed shell sorting; d) color sorting; e) drying: transferring the color-sorted camellia seeds to a drum dryer and drying them at a temperature of 100°C for 20 minutes; f) impurity removal: the dried tea seeds are transported to a magnetic separator and a flat rotary screen via a conveyor line to remove impurities such as iron and stones; g) shelling: the tea seeds with impurities removed are transported to a shelling machine, with a roller line speed of 9.5 m / s; h) oil pressing: the tea kernels obtained by shelling are transported to a press via a conveyor line, the chamber temperature of the press is set to 70°C, and the pressing is stopped after the residual oil rate of the pressed tea cake is 5%; i) filtering to obtain pressed tea seed oil and tea seed cake; the moisture content of the tea seed cake is controlled to be 14%;

[0037] 2) Extrusion puffing: firstly put the tea seed cake into the puffing machine, control the screw speed to 240r / min, and the puffing temperature to 70°C, to obtain a loose, porous and disordered tea seed cake; then crush the puffed tea seed cake into 80 meshes to obtain puffed tea seed cake powder;

[0038] 3) Pretreatment of glycerol and catechin: adding glycerol and catechin to the puffed tea meal powder, the solid-liquid ratio (m / v) of puffed tea meal powder to glycerol is 1:15, the mass ratio of puffed tea meal powder to catechin is 1:0.006, stirring with magnetic force at 70°C for 1.5h, mixing thoroughly, and obtaining a tea meal powder mixture;

[0039] 4) Ultrahigh pressure treatment: the tea meal powder mixture and the pressed tea seed oil are mixed uniformly at a mass ratio of 1:15 and then subjected to ultrahigh pressure treatment at a pressure of 850 MPa, a temperature of 45° C., and a time of 2.5 min to obtain a meal-oil mixture;

[0040] 5) Filtration: Filter the meal-oil mixture to remove the meal and obtain a mixed oil;

[0041] 6) Add water and centrifuge: Add water to the mixed oil at a volume ratio of 1:1 to dissolve glycerol in water, centrifuge at a speed of 10000r / min for 6 minutes, obtain the upper oil phase of camellia oil, the lower water phase of water and glycerol, take the upper oil phase, and obtain the finished camellia oil with strong flavor and safety. After testing, the acid value of the finished camellia oil is 0.2mgKOH / g, and the peroxide value is 0.018g / 100g, which meets the first-level standard of camellia oil GB / T 11765-2018.

[0042] Example 2

[0043] A method for preparing camellia oil with strong flavor and safety, comprising the following steps:

[0044] 1) Extraction of freshly pressed camellia oil: extracting camellia oil from camellia seeds by pressing to obtain pressed camellia oil and camellia cake, specifically comprising the following steps: a) removing impurities from fresh fruit: removing dirt, stones, leaves, tree trunks and other impurities to obtain clean camellia seeds; b) kneading and crushing: adopting an extrusion kneading method, controlling the kneading machine speed to 130r / min; c) seed shell sorting; d) color sorting; e) drying: transferring the color-sorted camellia seeds to a drum dryer and drying them at a temperature of 100°C for 20 minutes; f) impurity removal: the dried tea seeds are transported to a magnetic separator and a flat rotary screen via a conveyor line to remove impurities such as iron and stones; g) shelling: the tea seeds with impurities removed are transported to a shelling machine, with a roller line speed of 9.5 m / s; h) oil pressing: the tea kernels obtained by shelling are transported to a press via a conveyor line, the chamber temperature of the press is set to 70°C, and the pressing is stopped after the residual oil rate of the pressed tea cake is 5%; i) filtering to obtain pressed tea seed oil and tea seed cake; the moisture content of the tea seed cake is controlled to be 16%;

[0045] 2) Extrusion puffing: firstly put the tea seed cake into the puffing machine, control the screw speed to 180r / min, and the puffing temperature to 60°C, to obtain a loose, porous and disordered tea seed cake; then crush the puffed tea seed cake into 80 meshes to obtain puffed tea seed cake powder;

[0046] 3) Pretreatment of glycerol and catechin: adding glycerol and catechin to the puffed tea meal powder, the solid-liquid ratio of the puffed tea meal powder to glycerol is 1:10, the mass ratio of the puffed tea meal powder to catechin is 1:0.008, stirring with magnetic force at a temperature of 50°C for 1h, mixing thoroughly, and obtaining a tea meal powder mixture;

[0047] 4) Ultrahigh pressure treatment: the tea meal powder mixture and the pressed tea seed oil are mixed uniformly at a mass ratio of 1:10 and then subjected to ultrahigh pressure treatment at a pressure of 800 MPa, a temperature of 40° C., and a time of 2 min to obtain a meal-oil mixture;

[0048] 5) Filtration: Filter the meal-oil mixture to remove the meal and obtain a mixed oil;

[0049] 6) Add water and centrifuge: Add water to the mixed oil at a volume ratio of 1:1 to dissolve glycerol in water, centrifuge at a speed of 8000r / min for 5 minutes, and obtain an upper oil phase of camellia oil and a lower water phase of water and glycerol. Take the upper oil phase to obtain a finished camellia oil with a strong flavor and safety. After testing, the acid value of the finished camellia oil is 0.21mgKOH / g, and the peroxide value is 0.019g / 100g, which meets the first-level pressing standard of camellia oil GB / T 11765-2018.

[0050] Example 3

[0051] A method for preparing camellia oil with strong flavor and safety, comprising the following steps:

[0052] 1) Extraction of freshly pressed camellia oil: extracting camellia oil from camellia seeds by pressing to obtain pressed camellia oil and camellia cake, specifically comprising the following steps: a) removing impurities from fresh fruit: removing dirt, stones, leaves, tree trunks and other impurities to obtain clean camellia seeds; b) kneading and crushing: adopting an extrusion kneading method, controlling the kneading machine speed to 130r / min; c) seed shell sorting; d) color sorting; e) drying: transferring the color-sorted camellia seeds to a drum dryer and drying them at a temperature of 100°C for 20 minutes; f) impurity removal: the dried tea seeds are transported to a magnetic separator and a flat rotary screen via a conveyor line to remove impurities such as iron and stones; g) shelling: the tea seeds with impurities removed are transported to a shelling machine, with a roller line speed of 9.5 m / s; h) oil pressing: the tea kernels obtained by shelling are transported to a press via a conveyor line, the chamber temperature of the press is set to 70°C, and the pressing is stopped after the residual oil rate of the pressed tea cake is 5%; i) filtering to obtain pressed tea seed oil and tea seed cake; the moisture content of the tea seed cake is controlled to be 18%;

[0053] 2) Extrusion puffing: firstly put the tea seed cake into the puffing machine, control the screw speed to 300r / min, and the puffing temperature to 80°C to obtain a loose, porous and disordered tea seed cake; then crush the puffed tea seed cake into 80 meshes to obtain puffed tea seed cake powder;

[0054] 3) Pretreatment of glycerol and catechin: adding glycerol and catechin to the puffed tea meal powder, the solid-liquid ratio of the puffed tea meal powder to glycerol is 1:20, the mass ratio of the puffed tea meal powder to catechin is 1:0.01, stirring with magnetic force at a temperature of 80°C for 2h, mixing thoroughly, and obtaining a tea meal powder mixture;

[0055] 4) Ultrahigh pressure treatment: the tea meal powder mixture and the pressed tea seed oil are mixed uniformly at a mass ratio of 1:20 and then subjected to ultrahigh pressure treatment at a pressure of 900 MPa, a temperature of 50° C., and a time of 3 min to obtain a meal-oil mixture;

[0056] 5) Filtration: Filter the meal-oil mixture to remove the meal and obtain a mixed oil;

[0057] 6) Add water and centrifuge: Add water to the mixed oil at a volume ratio of 1:1 to dissolve glycerol in water, centrifuge at a speed of 12000r / min for 8 minutes, and obtain an upper oil phase of camellia oil and a lower water phase of water and glycerol. Take the upper oil phase to obtain a finished camellia oil with a strong flavor and safety. After testing, the acid value of the finished camellia oil is 0.20mgKOH / g, and the peroxide value is 0.019g / 100g, which meets the first-level standard of camellia oil GB / T 11765-2018.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that: step 2) is not included, and glycerol and catechins are directly added to the crushed tea seed cake. The other steps are the same as those in Example 1.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 1 is that: Step 3) is not included, and the expanded tea seed meal powder is directly subjected to ultrahigh pressure treatment. The other steps are the same as those in Example 1.

[0062] Comparative Example 3

[0063] The difference between this comparative example and Example 1 is that glycerol is not added in step 3). The other steps are the same as those in Example 1.

[0064] Comparative Example 4

[0065] The difference between this comparative example and Example 1 is that catechin is not added in step 3). The other steps are the same as those in Example 1.

[0066] Comparative Example 5

[0067] The difference between this comparative example and Example 1 is that: in step 4), no ultrahigh pressure treatment is performed, and a heating treatment is performed directly. The specific operation steps are: the tea meal powder mixture and the pressed tea seed oil are mixed evenly in a ratio of 1:15, and then heated at a temperature of 40°C for 2 minutes to obtain a meal oil mixture.

[0068] The differences in the methods for preparing camellia oil between Example 1 and Comparative Examples 1-5 are shown in the following table:

[0069] Table 1 Differences in the method for preparing camellia oil between Example 1 and Comparative Examples 1-5

[0070]

[0071]

[0072] The present invention measures the content and flavor of furfural and 5-hydroxymethylfurfural in the camellia oil prepared in Examples 1-3 and Comparative Examples 1-5 and the pressed camellia oil, and the specific measurement methods are:

[0073] Determination method of 5-hydroxymethylfurfural content: refer to "The formation law and safety evaluation of 5-hydroxymethylfurfural in black garlic", weigh 1.0g of the tea seed oil sample to be tested into a 50mL volumetric flask, add 3mL 10.6% (m / v) potassium ferrocyanide solution and 3mL 21.9% (m / v) zinc acetate solution, shake vigorously and let stand for 15min. Make up to volume with methanol, mix well and filter with 0.22um organic filter membrane and then determine with high performance liquid chromatography. Liquid chromatography conditions are: chromatographic column: C18 (5um, 4.6×250mm), column temperature: 35℃, injection volume: 10uL, wavelength: 284nm, mobile phase: 85% water + 15% methanol isocratic elution, flow rate: 1.0mL / min. Standard curve of 5-hydroxymethylfurfural: y=76043x-72990, R 2 =0.9998, where the concentrations of 5-hydroxymethylfurfural standard solution are: 5ug / ml, 10ug / ml, 20ug / ml, 50ug / ml, 100ug / ml, 250ug / ml.

[0074] Determination method of furfural content: refer to "Study on the formation of DDMP, HMF and furfural in caramelization and Maillard reaction", weigh 1.0g of tea seed oil sample to be tested, and use high performance liquid chromatography for detection. The chromatographic conditions are: C18 (5um, 4.6×250mm), column temperature: 25℃, injection volume 20uL, flow rate 1.0ml / min, detection wavelength 284nm, mobile phase: A is methanol, B is water, gradient elution. Standard curve of furfural: y=32532x-76624, R 2 =0.9990, where the concentrations of furfural standard solution are: 5ug / ml, 10ug / ml, 20ug / ml, 50ug / ml, 100ug / ml, 250ug / ml.

[0075] Sensory evaluation of flavor: The sensory evaluation of the flavor of camellia oil was conducted by screening 20 trained professionals. The experimental samples were scored for sensory evaluation of different indicators and scored based on different evaluation options. The evaluation details are shown in Table 2:

[0076] Table 2 Sensory scoring standards for camellia oil flavor

[0077]

[0078] The flavor sensory score is calculated using the total score of camellia oil flavor, burnt smell and persistence. The flavor sensory score divides the flavor intensity of camellia oil into three levels, from weak to strong: not strong (0-5 points), relatively strong (6-11 points), and very strong (12-18 points).

[0079] The results of the contents and flavors of furfural and 5-hydroxymethylfurfural in the camellia oil prepared in Examples 1-3 and Comparative Examples 1-5 and the pressed camellia oil are shown in Table 3.

[0080] Table 3 Results of the contents and flavors of furfural and 5-hydroxymethylfurfural in the tea seed oils prepared in Examples 1-3 and Comparative Examples 1-5 and the pressed tea seed oils

[0081]

[0082] As can be seen from Table 3, the contents of furfural and 5-hydroxymethylfurfural in the camellia oil prepared in Examples 1-3 are not significantly different from those in the pressed camellia oil, and the corresponding contents of furfural and 5-hydroxymethylfurfural are lower than those in Comparative Examples 1-4, indicating that the preparation method of Examples 1-3 can significantly inhibit the formation of furfural and 5-hydroxymethylfurfural, greatly improving the safety of camellia oil; and the prepared camellia oil has a very strong flavor characteristic, which can greatly improve the flavor of camellia oil.

[0083] Compared with Example 1, Comparative Example 1 lacks the extrusion puffing process, and the corresponding furfural and 5-hydroxymethylfurfural contents are not significantly different from those of the camellia oil prepared in Example 1. This may be because glycerol and catechins are also added to Comparative Example 1 for treatment, and glycerol and catechins can effectively inhibit the formation of furfural and 5-hydroxymethylfurfural, so that the furfural and 5-hydroxymethylfurfural contents contained therein are also low; however, the aroma of the camellia oil in Comparative Example 1 is not as strong as that in Example 1, indicating that the extrusion puffing treatment and glycerol treatment can effectively improve the rich flavor of the camellia oil, which may be because the extrusion puffing treatment can make the structure of the camellia cake more loose and porous, increase the contact area between glycerol, catechins and the camellia cake, and at the same time improve the enzymatic activity of cellulase, increase the degree of cellulose degradation, thereby increasing the substrate for the subsequent Maillard reaction, forming more aromatic compounds, and thus improving the flavor of the camellia oil;

[0084] And because glycerol and catechin are also added in comparative example 1 for treatment, glycerol and catechin can effectively inhibit the content of furfural and 5-hydroxymethylfurfural, so that the content of furfural and 5-methylfurfural corresponding to comparative example 1 is significantly lower than that of comparative examples 2-4, and the generation of furfural and 5-hydroxymethylfurfural can be inhibited to a certain extent.

[0085] Compared with Example 1, Comparative Example 2 does not add glycerol and catechins for treatment, and the corresponding furfural and 5-hydroxymethylfurfural contents are significantly higher than those in Example 1 and Comparative Example 1, Comparative Example 3, and Comparative Example 4, but the prepared camellia oil still has a strong flavor, which may be due to the following reasons: extrusion puffing provides more Maillard reaction substrates, and ultrahigh pressure treatment effectively promotes the Maillard reaction, so that the prepared camellia oil has a strong aroma, but since Comparative Example 2 does not add glycerol and catechins, the process of degradation into furfural and 5-hydroxymethylfurfural in the Maillard reaction is not effectively inhibited, so that the furfural and 5-hydroxymethylfurfural in the prepared camellia oil are significantly higher than those in Example 1, Comparative Example 1, Comparative Example 3, and Comparative Example 4. It is shown that only on the basis of the process of extrusion puffing and ultrahigh pressure treatment, combined with glycerol and catechin pretreatment, can the camellia oil have a very strong flavor, and at the same time, the content of furfural and 5-hydroxymethylfurfural in the oil can be effectively reduced, thereby improving the safety of the camellia oil.

[0086] Compared with Example 1, Comparative Examples 3 and 4 were treated with only catechin and glycerol, respectively, and the corresponding furfural and 5-hydroxymethylfurfural contents were significantly higher than those in Example 1, and the flavor level was lower than that in Example 1, indicating that there was a synergistic effect between glycerol and catechin. Compared with adding only one of them, the synergistic addition of the two could better control the production of furfural and 5-hydroxymethylfurfural, which may be related to the fact that glycerol can cooperate with catechin to quench 3-deoxyglucosone, thereby inhibiting the production of furfural and 5-hydroxymethylfurfural. In addition, when glycerol and catechin are added at the same time, glycerol can play the role of oil seal, which can effectively protect catechin from oxidation and reduce the production of furfural and 5-hydroxymethylfurfural.

[0087] Compared with Example 1, Comparative Example 5 does not use ultra-high pressure treatment for Maillard reaction, but only uses heating treatment. The corresponding furfural and 5-hydroxymethylfurfural contents are not significantly different from those in Example 1, and the flavor is slightly richer than that of the pressed camellia seeds, but significantly lower than that of Example 1. It is impossible to provide camellia oil with a very strong flavor, indicating that only when extrusion, glycerol and catechin treatment are combined with ultra-high pressure treatment for Maillard reaction can a camellia oil with high safety and a very strong flavor be provided.

[0088] Experimental Example 1 Effects of glycerol and catechin pretreatment on cellulase and reducing sugar in puffed tea seed meal powder

[0089] This experimental example adopts the method in Example 1, and takes the mixed solution of glycerol and catechin pretreatment steps, and the stirring time is 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, respectively, and the cellulase activity and reducing sugar content in the mixed solution are determined. The results are shown in Table 4. Among them, the method for determining cellulase activity refers to the method for determining filter paper enzyme activity in GB / T 23881-2009; the method for determining reducing sugar content: refer to "Study on the Effect of Enzymatic Hydrolysis of Reducing Sugar from Sunflower Seeds on the Flavor of Rich Sunflower Seed Oil", and the sample is mixed with ultrapure water. After the sample solution is appropriately diluted, 1.0mL is sucked into a 15mL glass tube with a rubber-tipped dropper. Then slowly add 2.0mL of the prepared DNS solution. Start boiling vigorously in a water bath for 2min and then stand on a test tube rack. Then pour ultrapure water to 15mL, and detect the absorbance value at a wavelength of 540nm. According to the standard curve of reducing sugar, calculate the content of reducing sugar in the sample. Reducing sugar content % = reducing sugar content in sample / mass of camellia seed cake * 100%, where glucose standard solution (1 mg / mL) is 0, 0.2, 0.4, 0.6, 0.8, 1.0. The standard curve is: y = 0.3569x + 0.0673, R 2 =0.9985.

[0090] Table 4 Effects of glycerol and catechin pretreatment on cellulase activity and reducing sugar content

[0091]

[0092] As can be seen from Table 4, when glycerol and catechins are added to the puffed tea dregs powder, as the stirring time increases, the cellulase activity and the reducing sugar content show a trend of first increasing and then flattening. This may be because the polysaccharides in the puffed tea dregs powder are continuously degraded into reducing sugars under the action of cellulase, so that the content of reducing sugars gradually increases. After stirring for 2 hours, the polysaccharides are almost completely degraded, and no new reducing sugars are produced, so that the content of reducing sugars remains stable. In order to provide more reaction substrates for the Maillard reaction during the subsequent ultra-high pressure treatment and effectively improve the preparation efficiency, the optimal pretreatment time is preferably 1h-2h, and the most preferred is 1.5h.

[0093] Experimental Example 2 Effect of Ultrahigh Pressure Treatment Pressure on Furfural, 5-Hydroxymethylfurfural and Flavor of Maillard Reaction Degradation Products

[0094] This experimental example refers to the method of comparative example 2 (treatment without adding glycerol and catechins) to investigate the preparation of camellia oil at different pressures (400MPa, 500MPa, 600MPa, 700MPa, 800MPa, 900MPa, 1000MPa) during the ultra-high pressure treatment step, and studies the effect of the pressure of ultra-high pressure treatment on the furfural and 5-hydroxymethylfurfural content generated by Maillard reaction degradation in camellia oil and the flavor. The results are shown in Figure 2-4 shown.

[0095] This experimental example refers to the method of Example 1 (adding glycerol and catechins) to investigate the ultra-high pressure treatment step, using different pressures (700MPa, 800MPa, 900MPa, 1000MPa) to prepare camellia oil, and studies the effect of the ultra-high pressure treatment pressure on the furfural and 5-hydroxymethylfurfural content and flavor generated by Maillard reaction degradation in camellia oil. The results are as follows Figure 2-4 shown.

[0096] Depend on Figure 2-4 It can be seen that when glycerol and catechins are not added, the contents of furfural and 5-hydroxymethylfurfural decrease at 400-600MPa, and the flavor is not strong; however, when the pressure continues to increase and exceeds 600MPa, the contents of furfural and 5-hydroxymethylfurfural and the flavor all show a significant upward trend, and when the pressure is 900MPa, the flavor score is 12 points, reaching a very strong level, but at this time the corresponding furfural and 5-hydroxymethylfurfural contents also reach the maximum, which greatly reduces the safety of camellia oil.

[0097] Therefore, in order to ensure that camellia oil has a very strong flavor while keeping the content of furfural and 5-hydroxymethylfurfural at a low level, so as to improve the flavor and safety of camellia oil, the inventors found that glycerol and catechin treatment can effectively inhibit the formation of furfural and 5-hydroxymethylfurfural. Therefore, the inventors began to add glycerol and catechins when the pressure was 700MPa>600MPa, and studied the effect of continuously increasing the pressure on furfural, 5-hydroxymethylfurfural and flavor in camellia oil on the basis of adding glycerol and catechins. Figure 2-4 The results showed that compared with the method without adding glycerol and catechins, after adding glycerol and catechins, as the pressure increased, the contents of furfural and 5-hydroxymethylfurfural were not significantly different from those when the pressure was 600MPa (without adding glycerol and catechins), and the flavor of camellia oil showed a very strong aroma, indicating that the addition of glycerol and catechins can not only reduce the growth rate of furfural and 5-hydroxymethylfurfural, reduce the content of furfural and 5-hydroxymethylfurfural, but also ensure that the camellia oil has a very strong flavor.

[0098] In addition, the flavor of camellia oil after treatment with glycerol and catechins can reach a very strong level at a pressure of 850MPa, while the flavor of camellia oil without the addition of glycerol and catechins needs to reach a very strong level at 900MPa. This shows that the pressure required for camellia oil to reach a very strong aroma can be effectively reduced by adding glycerol and catechins, thereby greatly reducing the experimental conditions required for preparing camellia oil with a very strong aroma, effectively reducing the preparation cost of camellia oil.

[0099] Experimental Example 3 Effect of Ultrahigh Pressure Treatment Time on Furfural, 5-Hydroxymethylfurfural Content and Flavor in Camellia Seed Oil

[0100] In this experimental example, camellia oil was prepared by referring to the steps of Example 1, and the effects of different ultrahigh pressure treatment times (1 min, 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min) on furfural, 5-hydroxymethylfurfural and flavor of the prepared camellia oil were studied. The results are shown in Table 5 below.

[0101] Table 5 Effect of ultrahigh pressure treatment time on the content and flavor of furfural and 5-hydroxymethylfurfural in camellia oil

[0102]

[0103] As can be seen from Table 5, as the ultra-high pressure treatment time increases, the contents of furfural and 5-hydroxymethylfurfural show a slight upward trend as a whole, but there is no significant difference between the treatment groups; however, the flavor of camellia oil shows a trend of first increasing and then decreasing as the treatment time increases. It may be that when the ultra-high pressure treatment time is long, volatile substances that are unfavorable to the fragrance of camellia oil will be produced, thereby significantly reducing the richness of its flavor. Based on the above phenomena, while ensuring low furfural and 5-hydroxymethylfurfural contents, in order to make camellia oil present a very strong flavor, the ultra-high pressure treatment time is selected to be 2min-3min, and the most preferred is 2.5min.

[0104] Experimental Example 4 Effect of the solid-liquid ratio of expanded tea seed powder to glycerol on the content and flavor of furfural and 5-hydroxymethylfurfural in tea seed oil

[0105] In this experimental example, camellia oil was prepared by referring to the steps of Example 1, and the effects of different solid-liquid ratios of puffed tea meal powder and glycerol (1:1, 1:5, 1:10, 1:15, 1:20, 1:25) on furfural, 5-hydroxymethylfurfural and flavor of the prepared camellia oil were studied. The results are shown in Table 6.

[0106] Table 6 Effect of the solid-liquid ratio of expanded tea seed powder to glycerol on the content and flavor of furfural and 5-hydroxymethylfurfural in tea seed oil

[0107]

[0108] As can be seen from Table 6 above, with the increase in the proportion of glycerol added, the contents of furfural and 5-hydroxymethylfurfural in the prepared tea seed oil first decrease and then tend to be flat; the flavor first increases and then tends to be flat. When the ratio of puffed tea meal powder to glycerol is 1:15, the contents of furfural and 5-hydroxymethylfurfural are the lowest, and the flavor is the strongest. Combining the three indicators of furfural, 5-hydroxymethylfurfural and flavor, and considering the production cost, the solid-liquid ratio of puffed tea meal powder to glycerol is selected as 1:(10-20), and the most preferred is 1:15.

[0109] Experimental Example 5 Effect of the mass ratio of expanded tea seed powder to catechins on furfural, 5-hydroxymethylfurfural and flavor in camellia oil

[0110] In this experimental example, tea seed oil was prepared according to the steps of Example 1, and the effects of different mass ratios of puffed tea meal powder to catechins (1:0.002, 1:0.004, 1:0.006, 1:0.008, 1:0.01, 1:0.012) on the furfural and 5-hydroxymethylfurfural contents and flavor of the prepared tea seed oil were studied. The results are shown in Table 7.

[0111] Table 7 Effect of the mass ratio of expanded tea seed powder to catechins on the content of furfural and 5-hydroxymethylfurfural and flavor in camellia oil

[0112]

[0113] As shown in Table 7, with the increasing proportion of catechins added, the contents of furfural and 5-hydroxymethylfurfural first decreased and then stabilized; the flavor first increased and then decreased. Considering the data and cost, the preferred mass ratio of puffed tea dregs to catechins is 1:(0.006-0.01), and the optimal is 1:0.006.

[0114] Experimental Example 5 Effect of the mass ratio of tea dregs powder mixture to pressed camellia oil on furfural, 5-hydroxymethylfurfural and flavor of camellia oil

[0115] In this experimental example, camellia oil was prepared by referring to the steps of Example 1, and the effects of different mass ratios of tea meal powder mixture to pressed camellia oil (1:1, 1:5, 1:10, 1:15, 1:20, 1:25) on furfural, 5-hydroxymethylfurfural and flavor of the prepared camellia oil were studied. The results are shown in Table 8 below.

[0116] Table 8 Effect of the mass ratio of tea seed powder mixture to pressed tea seed oil on the content of furfural and 5-hydroxymethylfurfural and flavor in tea seed oil

[0117]

[0118] It can be seen from Table 8 that with the continuous increase in the mass ratio of the tea dregs powder mixture to the pressed tea seed oil, the contents of furfural and 5-hydroxymethylfurfural first decrease and then tend to be flat; the flavor first increases and then tends to be flat. Considering furfural, 5-hydroxymethylfurfural, flavor and cost, the preferred mass ratio of the tea dregs powder mixture to the pressed tea seed oil is 1: (10-20), and the most preferred is 1:15.

[0119] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing camellia oil with strong flavor and safety, characterized in that: The following steps are involved: 1) Extraction of freshly pressed camellia oil: extracting camellia oil from camellia seeds by pressing to obtain pressed camellia oil and camellia cake; 2) Extrusion and puffing: firstly, the tea seed cake is subjected to extrusion and puffing treatment, and then crushed to obtain puffed tea seed cake powder; 3) Pretreatment of glycerol and catechins: adding glycerol and catechins to the expanded tea dregs powder, stirring with a magnetic stirrer, and mixing thoroughly to obtain a tea dregs powder mixture; 4) Ultrahigh pressure treatment: the tea meal powder mixture and the pressed tea seed oil are mixed evenly and then subjected to ultrahigh pressure treatment, the pressure of the ultrahigh pressure treatment is 800-900 MPa, the temperature is 40-50° C., and the time is 2-3 min to obtain a meal oil mixture; 5) filtering to obtain a mixed oil; 6) Add water and centrifuge: Add water to the mixed oil, centrifuge, take the upper oil phase, and obtain a finished camellia oil with a strong flavor and safety.

2. The method for preparing a flavorful and safe camellia oil according to claim 1, characterized in that: The screw speed during extrusion puffing in step 2 is 180-300 r / min, and the puffing temperature is 60-80°C.

3. The method for preparing a strong-flavored and safe camellia oil according to claim 1, characterized in that: In the step 3), the solid-liquid ratio of the puffed tea dregs powder to glycerin is 1:(10-20), and the mass ratio of the puffed tea dregs powder to catechins is 1:(0.006-0.01).

4. The method for preparing a strong-flavored and safe camellia oil as claimed in claim 3, characterized in that: The solid-liquid ratio of the puffed tea dregs powder to glycerol is 1:15, and the mass ratio of the puffed tea dregs powder to catechins is 1:0.

006.

5. The method for preparing a strong-flavored and safe camellia oil according to claim 1, characterized in that: The temperature during magnetic stirring in step 3) is 50-80° C., and the stirring time is 1-2 h.

6. The method for preparing a strong-flavored and safe camellia oil according to claim 1, characterized in that: In the step 4), the mass ratio of the tea dregs powder mixture to the pressed tea seed oil is 1:(10-20).

7. The method for preparing a strong-flavored and safe camellia oil according to claim 1, characterized in that: In the step 4), the ultra-high pressure treatment is performed at a pressure of 850 MPa, a temperature of 45° C., and a time of 2.5 min.

8. The method for preparing the camellia oil with strong flavor and safety as claimed in claim 1, characterized in that: The specific operation steps of step 6) are: adding distilled water to the mixed oil at a volume ratio of 1:1, mixing thoroughly, dissolving glycerol in the distilled water, centrifuging, taking the upper oil phase, and obtaining the finished camellia oil.

9. The method for preparing a strong-flavored and safe camellia oil as claimed in claim 8, characterized in that: The centrifugal speed is 8000r / min-12000r / min, and the time is 5-8min.

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