Method for improving oxidation stability of vegetable fat

Abstract

The invention provides a method for improving oxidation stability of vegetable fat, which specifically comprises the following steps: S1, adding polyphenol, carotenoid and gallic acid into the vegetable fat, and emulsifying to obtain a mixed oil solution; s2, adding a stabilizer and a crystallization inhibitor into the mixed oil solution, standing and filtering to obtain a transparent oil solution; s3, adding a ferric sulfate solution and a copper sulfate solution into the transparent oil solution to obtain the vegetable fat with high oxidation stability. The polyphenols, the carotenoid and the gallic acid are added to achieve a synergistic effect, so that the oxidation stability of the grease is improved; phospholipids in the grease are complexed with metal ions, so that the oxidation resistance of the grease is improved; in addition, polyphenol, carotenoid, gallic acid and metal ions form a complex, the oxidation resistance of grease is enhanced, and the application range in the fields of food and the like is widened.

Description

Technical Field

[0001] The invention belongs to the technical field of oil modification, and in particular relates to a method for improving the oxidation stability of vegetable oils. Background Art

[0002] Oils and fats are essential for people's daily diet. They can provide energy and essential fatty acids for the human body and participate in human growth and metabolism. However, since oils and fats are rich in unsaturated fatty acids, they are often affected by light, heat, oxygen, moisture and enzymes during oil processing and storage, producing a "rancid" taste, that is, oxidative rancidity, which not only causes flavor changes and a decrease in nutritional value, but also produces harmful substances. Antioxidants are organic substances added to oils and fats to slow down their self-oxidation process and extend the shelf life of food. For a long time, the food industry has been using synthetic antioxidants such as BHA, BHT and TBHQ to preserve freshness and prevent oxidation. However, due to their many side effects, they are restricted in many countries. Finding and developing natural antioxidants has become a hot topic in this field. Natural antioxidants mainly come from plant polyphenols. The ortho-phenolic hydroxyl groups in the phenolic hydroxyl structure of plant polyphenols (catechol or pyrogallol) can be easily oxidized into quinone structures, consuming oxygen in the environment. At the same time, they have a strong ability to capture free radicals such as active oxygen, which makes polyphenols have strong antioxidant properties and the ability to scavenge free radicals. In the prior art, oil-soluble polyphenols are often used in the form of oil suspensions. As the storage time increases, the polyphenols are prone to crystallization and precipitation, resulting in uneven distribution. The upper layer will become a clear oil phase, and the lower layer is the polyphenol crystallization precipitation. Problems such as crystal spots or precipitation appear in the food have an adverse effect on food quality. Carotenoids is a general term for an important class of natural pigments, which are commonly found in yellow, orange-red or red pigments of animals, higher plants, fungi and algae. Carotenoids are the main source of vitamin A in the body, and also have antioxidant, immunomodulatory, anti-cancer and anti-aging effects. Gallic acid, with the chemical name 3,4,5-trihydroxybenzoic acid, is a polyphenolic organic compound that is widely found in plants such as Rheum palmatum, Eucalyptus globulus, and Cornus officinalis. Gallic acid has multiple biological activities such as anti-inflammatory, anti-mutagenic, antioxidant, and anti-free radical, and is widely used in food, biology, medicine, and chemical industries. Usually, plants and plant seeds contain more trace elements, such as iron, calcium, magnesium, zinc, manganese, etc., which usually exist in the form of complex salts. In the process of oil production and refining, through air separation, degumming, alkali refining, water washing, decolorization and other steps, common metal ions in refined oils, such as iron and copper ions, are not detected. The presence of free metal ions in oils, especially iron and copper ions, will cause rapid oxidation of oils. According to reports, when there is 0.1ppm of iron or copper ions, the oxidation induction time of oils is greatly shortened. Therefore, it is very necessary to seek a substance that reacts with metal ions to inhibit oil oxidation and improve oil stability. Summary of the invention

[0003] Technical problems to be solved: In view of the above technical problems, the purpose of the present invention is to provide a method for improving the oxidative stability of vegetable oils and fats, which specifically includes the following steps: S1. Add polyphenols, carotenoids and gallic acid to vegetable oils and fats, emulsify, and obtain a mixed oil solution; S2. Add stabilizers and crystallization inhibitors to the mixed oil solution to obtain a transparent oil solution; S3. Add ferrous sulfate solution and copper sulfate solution to the transparent oil solution to obtain high oxidative stability vegetable oils and fats. The addition of polyphenols and carotenoids in the present invention can improve the oxidative stability of oils and fats; the phospholipids in the oils and fats are complexed with metal ions to enhance the antioxidant properties of the oils and fats; in addition, polyphenols, carotenoids, gallic acid and metal ions form complexes to exert synergistic effects, enhance the antioxidant properties of oils and fats, and expand the scope of application in food and other fields.

[0004] Technical solution: A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Adding polyphenols, carotenoids and gallic acid to vegetable oils and fats, emulsifying, and obtaining a mixed oil solution; S2. Add a stabilizer and a crystallization inhibitor to the mixed oil solution, stir evenly, let stand, and filter to obtain a transparent oil solution; S3. Add ferric sulfate solution and copper sulfate solution to the transparent oil solution, react at 120-150°C for 8-10 hours, and stir evenly to obtain vegetable oil with high oxidation stability. Furthermore, in step S1, the vegetable oils include tomato seed oil, passion fruit seed oil, melon oil and garlic fruit oil; and the polyphenols include vanillic acid, quercetin, curcumin and oil-soluble tea polyphenols. Furthermore, in step S1, the mass volume ratio of polyphenols to vegetable oils is 1:(100-200); the mass ratio of polyphenols to carotenoids and gallic acid is 1:(0.8-1.2):(0.05-0.1). Furthermore, the emulsification condition in step S1 is stirring at a temperature of 70-120° C. for 20-40 min. Furthermore, in step S2, the stabilizer is glycerol or sorbitol; and the crystallization inhibitor is Tween, phospholipid or sucrose fatty acid ester. Furthermore, the mass ratio of the polyphenol, the stabilizer and the crystallization inhibitor is 1:(0.5-2.5):(0.02-2). Furthermore, in step S2, the stirring speed is 300-600 r / min, and the stirring time is 30-60 min. Furthermore, the iron ion content in the ferric sulfate solution in step S3 is 0.0005-0.001 ppm; the copper ion content in the copper sulfate solution is 0.0002-0.0008 ppm. Furthermore, the method described above can obtain vegetable oil with high oxidation stability. Furthermore, the high oxidative stability vegetable oil is used in blood sugar and lipid lowering products. Beneficial effects: 1. In the present invention, polyphenols are added to vegetable oils and fats to effectively delay the oxidation of vegetable oils and fats; the addition of carotenoids can also play an antioxidant role in oils and fats, and polyphenols and carotenoids also have the effect of lowering blood sugar and lipids; gallic acid acts as a synergist of polyphenols and carotenoids, exerting a synergistic effect and improving the oxidative stability of oils and fats; 2. The present invention adds a stabilizer and a crystallization inhibitor to the system to prepare a uniform transparent oil solution, thereby avoiding the phenomenon of crystallization or precipitation of polyphenols as the storage time increases. The addition of the stabilizer and the crystallization inhibitor can improve the uniformity of the food system, thereby improving the food quality; 3. The present invention adds beneficial metal ions such as iron ions and copper ions to vegetable oils and fats. Under high temperature conditions, less oxygen is dissolved in the oils and fats, and the metal ions can react with the oxygen therein, resulting in a reduction in the oxygen content that reacts with the oils and fats, thereby reducing the peroxide value of the oils and fats. At the same time, the complexation of phospholipids in the oils and fats with metal ions makes the phospholipids have antioxidant properties. As a synergist, it can enhance the effect of antioxidants such as tocopherol, thereby further improving the oxidative stability of the oils and fats. In addition, the addition of beneficial metal ions can also supplement the trace elements necessary for the human body and maintain human metabolism. 4. The polyphenols, carotenoids and gallic acid added in the present invention can all react with metal ions to form stable multi-component complexes, forming a metal network system, which is beneficial to improving the stability and bioavailability of metal ions and avoiding the rapid oxidation of oils and fats. Multiple substances play a synergistic role, improve the stability and antioxidant properties of oils and fats, and extend the shelf life of food. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 The peroxide value of the high oxidative stability vegetable oils prepared in Example 6 and Comparative Examples 1-4; Figure 2 The acid value of the high oxidative stability vegetable oils prepared in Example 6 and Comparative Examples 1-4; Figure 3 The vegetable oils prepared in Example 6 and Comparative Examples 1-4 intervened in the body weight of obese mice induced by a high-fat diet; Figure 4 The vegetable oils prepared in Example 6 and Comparative Examples 1-4 intervened in the blood sugar of obese mice induced by a high-fat diet. DETAILED DESCRIPTION The present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are explanations of the present invention and the present invention is not limited to the following embodiments: Example 1 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of vanillic acid, 0.8 kg of carotenoids and 0.05 kg of gallic acid to 100 L of tomato seed oil, and stir at 70 ° C for 40 min to obtain a mixed oil solution; S2. Glycerol and Tween were added to the mixed oil solution, the mass ratio of vanillic acid, stabilizer and crystallization inhibitor was 1:0.5:0.02, stirred at 300 r / min for 60 min, allowed to stand, and filtered to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0005 ppm) and copper sulfate solution (copper ion content is 0.0002 ppm) to the transparent oil solution, react at 120° C. for 10 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 2 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of vanillic acid, 0.8 kg of carotenoids and 0.05 kg of gallic acid to 110 L of tomato seed oil, and stir at 70 ° C for 38 min to obtain a mixed oil solution; S2. Glycerol and Tween were added to the mixed oil solution, the mass ratio of vanillic acid, stabilizer and crystallization inhibitor was 1:0.8:0.04, stirred at 300 r / min for 60 min, allowed to stand, and filtered to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0005 ppm) and copper sulfate solution (copper ion content is 0.0002 ppm) to the transparent oil solution, react at 120°C for 9.5 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 3 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of vanillic acid, 0.9 kg of carotenoids and 0.06 kg of gallic acid to 120 L of tomato seed oil, and stir at 80 ° C for 35 min to obtain a mixed oil solution; S2. Add glycerol and phospholipids to the mixed oil solution, vanillic acid, stabilizer and crystallization inhibitor in a mass ratio of 1:0.8:0.06, stir at 400r / min for 50min, let stand, and filter to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0006 ppm) and copper sulfate solution (copper ion content is 0.0003 ppm) to the transparent oil solution, react at 130°C for 9 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 4 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. 1 kg quercetin, 0.8 kg carotenoids and 0.06 kg gallic acid were added to 130 L passion fruit seed oil and stirred at 80 ° C for 32 min to obtain a mixed oil solution; S2. Add glycerol and phospholipids to the mixed oil solution, the mass ratio of quercetin, stabilizer and crystallization inhibitor is 1:1.0:0.08, stir at 400r / min for 50min, let stand, filter, and obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0006 ppm) and copper sulfate solution (copper ion content is 0.0003 ppm) to the transparent oil solution, react at 130°C for 9 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 5 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of quercetin, 0.9 kg of carotenoids and 0.07 kg of gallic acid to 140 L of passion fruit seed oil, and stir at 90 ° C for 30 min to obtain a mixed oil solution; S2. Glycerol and sucrose fatty acid esters were added to the mixed oil solution, the mass ratio of quercetin, stabilizer and crystallization inhibitor was 1:1.2:1.0, stirred at 400r / min for 45min, allowed to stand, filtered, and a transparent oil solution was obtained; S3. Add ferric sulfate solution (iron ion content is 0.0007 ppm) and copper sulfate solution (copper ion content is 0.0004 ppm) to the transparent oil solution, react at 140°C for 8.5 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 6 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of curcumin, 1.0 kg of carotenoids and 0.07 kg of gallic acid to 150 L of melon oil and stir at 90 ° C for 28 min to obtain a mixed oil solution; S2. Glycerol and Tween were added to the mixed oil solution, the mass ratio of curcumin, stabilizer and crystallization inhibitor was 1:1.5:1.4, stirred at 500r / min for 40min, allowed to stand, and filtered to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0007 ppm) and copper sulfate solution (copper ion content is 0.0004 ppm) to the transparent oil solution, react at 140°C for 8.5 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 7 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of curcumin, 1.0 kg of carotenoids and 0.08 kg of gallic acid to 160 L of melon oil, and stir at 100 ° C for 26 min to obtain a mixed oil solution; S2. Sorbitol and Tween were added to the mixed oil solution, the mass ratio of curcumin, stabilizer and crystallization inhibitor was 1:1.6:1.6, stirred at 500r / min for 40min, allowed to stand, and filtered to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0008 ppm) and copper sulfate solution (copper ion content is 0.0006 ppm) to the transparent oil solution, react at 140°C for 8.4 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 8 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of curcumin, 1.1 kg of carotenoids and 0.08 kg of gallic acid to 170 L of melon oil, and stir at 100 ° C for 24 min to obtain a mixed oil solution; S2. Sorbitol and sucrose fatty acid esters were added to the mixed oil solution, the mass ratio of curcumin, stabilizer and crystallization inhibitor was 1:2.0:1.6, stirred at 600r / min for 35min, allowed to stand, filtered, and a transparent oil solution was obtained; S3. Add ferric sulfate solution (iron ion content is 0.0008 ppm) and copper sulfate solution (copper ion content is 0.0007 ppm) to the transparent oil solution, react at 150° C. for 8 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 9 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of polyphenols, 1.1 kg of carotenoids and 0.09 kg of gallic acid to 180 L of garlic fruit oil, and stir at 110 ° C for 22 minutes to obtain a mixed oil solution; S2. Sorbitol and Tween were added to the mixed oil solution, the mass ratio of polyphenols, stabilizer and crystallization inhibitor was 1:2.2:1.8, stirred at 600r / min for 30min, allowed to stand, and filtered to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.001 ppm) and copper sulfate solution (copper ion content is 0.0008 ppm) to the transparent oil solution, react at 150°C for 8 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Example 10 A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of oil-soluble tea polyphenols, 1.2 kg of carotenoids and 0.1 kg of gallic acid to 200 L of garlic fruit oil, and stir at 120 ° C for 20 min to obtain a mixed oil solution; S2. Add sorbitol and phospholipids to the mixed oil solution, the mass ratio of oil-soluble tea polyphenols, stabilizer and crystallization inhibitor is 1:2.5:2.0, stir at 600r / min for 30min, let stand, filter, and obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.001 ppm) and copper sulfate solution (copper ion content is 0.0008 ppm) to the transparent oil solution, react at 150°C for 8 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Comparative Example 1 The difference between this comparative example and Example 6 is that no polyphenols are added, as follows: A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1.0 kg of carotenoids and 0.07 kg of gallic acid to 150 L of melon oil, and stir at 90 ° C for 28 min to obtain a mixed oil solution; S2. Glycerol and Tween were added to the mixed oil solution, the mass ratio of curcumin, stabilizer and crystallization inhibitor was 1:1.5:1.4, stirred at 500r / min for 40min, allowed to stand, and filtered to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0007 ppm) and copper sulfate solution (copper ion content is 0.0004 ppm) to the transparent oil solution, react at 140°C for 8.5 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Comparative Example 2 The difference between this comparative example and Example 6 is that no carotenoids are added, as follows: A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of curcumin, 1.0 kg of carotenoids and 0.07 kg of gallic acid to 150 L of melon oil and stir at 90 ° C for 28 min to obtain a mixed oil solution; S2. Glycerol and Tween were added to the mixed oil solution, the mass ratio of curcumin, stabilizer and crystallization inhibitor was 1:1.5:1.4, stirred at 500r / min for 40min, allowed to stand, and filtered to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0007 ppm) and copper sulfate solution (copper ion content is 0.0004 ppm) to the transparent oil solution, react at 140°C for 8.5 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Comparative Example 3 The difference between this comparative example and Example 6 is that gallic acid is not added, as follows: A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of curcumin and 1.0 kg of carotenoids to 150 L of melon oil and stir at 90 ° C for 28 min to obtain a mixed oil solution; S2. Glycerol and Tween were added to the mixed oil solution, the mass ratio of curcumin, stabilizer and crystallization inhibitor was 1:1.5:1.4, stirred at 500r / min for 40min, allowed to stand, and filtered to obtain a transparent oil solution; S3. Add ferric sulfate solution (iron ion content is 0.0007 ppm) and copper sulfate solution (copper ion content is 0.0004 ppm) to the transparent oil solution, react at 140°C for 8.5 hours, stir evenly, and obtain vegetable oil with high oxidation stability. Comparative Example 4 The difference between this comparative example and Example 6 is that no metal ions are added, as follows: A method for improving the oxidative stability of vegetable oils and fats, comprising the following steps: S1. Add 1 kg of curcumin, 1.0 kg of carotenoids and 0.07 kg of gallic acid to 150 L of melon oil and stir at 90 ° C for 28 min to obtain a mixed oil solution; S2. Add glycerol and Tween to the mixed oil solution, with the mass ratio of curcumin, stabilizer and crystallization inhibitor being 1:1.5:1.4, stir at 500 r / min for 40 min, let stand, and filter to obtain a vegetable oil with high oxidative stability. Performance Test: (1) Oxidative stability 1. Schhal oven accelerated oxidation method to evaluate the oxidative stability of vegetable oils The Schhal oven method was used to place the high oxidative stability vegetable oils prepared in Example 6 and Comparative Examples 1-4 in a constant temperature oven at 55° C. for intensive preservation. The oil samples were shaken every 24 hours to mix the insoluble matter with the oil samples, and the positions of the oil samples in the oven were constantly exchanged. Unmodified vegetable oils were used as blank samples for comparison. The peroxide value (POV) of the oil samples was regularly measured with reference to GB / T 5009.37-2003 "Analysis Method for Hygienic Standards of Edible Vegetable Oils", and calculated according to the following formula: POV=(V1-V2)×C×0.1269×100 / M×78.8 In the formula, POV is the peroxide value of the sample, meq / kg; V1 is the volume of Na2S2O3 standard titration solution consumed by the sample, mL; V2 is the volume of Na2S2O3 standard titration solution consumed by the reagent blank, mL; C is the concentration of Na2S2O3 standard titration solution, mol / L; M is the sample mass, g; 0.1269 is the mass of iodine equivalent to 1mL Na2S2O3 standard titration solution (c(Na2S2O3)=1.000mol / L), g; 78.8 is the conversion factor. Depend on Figure 1 It can be seen that the peroxide value of the oil in the blank group gradually increases with time, indicating that the oil is constantly oxidized; the peroxide value of the oil prepared in Example 6 continues to decrease with time, indicating that the modified substance added to the plant oil in the present invention has a significant antioxidant effect on the plant oil; the peroxide value change trend of the oil prepared in Comparative Example 1 without adding polyphenols and Comparative Example 2 without adding carotenoids is similar, and from the third day, the peroxide value is higher than that in Example 6, which shows that the addition of polyphenols or carotenoids has a certain inhibitory effect on the oxidation of plant oils; Comparative Example 3 does not add gallic acid, and gallic acid can be used as a synergist, so the peroxide value of the prepared oil is significantly higher than that in Example 6; Comparative Example 4 does not add metal ions, polyphenols, carotenoids and gallic acid cannot form a stable multi-component complex with metal ions, and metal ions cannot react with oxygen, reducing the oxygen content in the oil, thereby accelerating the oxidation rate of the oil. 2. Rancimat method for evaluating the oxidative stability of vegetable oils The Rancimat method was used to evaluate the oxidative stability of vegetable oils. 3 g of the high oxidative stability vegetable oils prepared in each embodiment and comparative example were weighed, and the oxidative stability was measured according to GB / T 21121-2007 “Determination of the oxidative stability of animal and vegetable oils” using a 743 Rancimat oil oxidative stability tester. The test temperature was 120° C. and the air flow rate was 10 h / L. Table 1 Oxidation induction time of high oxidation stability vegetable oils prepared in each embodiment and comparative example sample Oxidation induction time (h) sample Oxidation induction time (h) Example 1 6.26 Example 8 6.22 Example 2 6.32 Example 9 6.45 Example 3 6.21 Example 10 6.48 Example 4 6.35 Comparative Example 1 4.72 Example 5 6.24 Comparative Example 2 4.68 Example 6 6.17 Comparative Example 3 4.05 Example 7 6.27 Comparative Example 4 3.55 As can be seen from Table 1, the oxidation induction time of the high oxidative stability vegetable oils prepared in the examples is significantly prolonged compared with the oxidation induction time of the vegetable oils prepared in the comparative examples. It can be seen that the addition of polyphenols, carotenoids, gallic acid and metal ions in the present invention can all play a certain role in delaying the oxidation of vegetable oils and improve the oxidative stability of vegetable oils and fats. (2) Acid value Refer to the first method in GB 5009.229-2016 "National Food Safety Standard Determination of Acid Value in Food", indicator titration method. Depend on Figure 2 It can be seen that the acid value of the high oxidative stability vegetable oils and fats in the oven accelerated oxidation process gradually increases with the extension of storage time, but the increase rate is different. The vegetable oil prepared in Example 6 has the slowest increase rate, which shows that the preparation method of the present invention has the best effect on inhibiting the rancidity of oils and fats; the acid value change trends of the oils and fats prepared in Comparative Example 1 without adding polyphenols and Comparative Example 2 without adding carotenoids are similar; Comparative Example 3 does not add gallic acid, and the rancidity of the oils and fats is significantly accelerated; Comparative Example 4 does not add metal ions, and the effect of inhibiting rancidity is poor. (3) Lipid-lowering effect Five-week-old C57BL / 6J male mice were selected and raised in an SPF mouse house (room temperature 25±2°C, relative humidity 45%-65%, 12h day and night light and dark alternation). After 7 days of adaptive feeding, the mice were weighed (experimental initial weight), and randomly divided into 6 groups, 12 mice in each group, 4 mice / cage for feeding, and high-fat diet (60% kcal, D12492; Research Diets). The blank group was gavaged with normal saline; the rest were gavaged with Example 6 and Comparative Examples 1-4 plant oils (100 mg / kg mouse body weight). After gavage for 12 weeks, the mice were weighed on an empty stomach (experimental end weight), and weight gain = experimental end weight - experimental initial weight. Depend on Figure 3 It can be seen that Example 6 shows an inhibitory effect on weight gain caused by a high-fat diet, which shows that the preparation method of the present invention has a significant alleviating effect on obesity; the weight gain trends of the oils prepared in Comparative Example 2 without adding carotenoids and Comparative Example 3 without adding gallic acid are similar; Comparative Example 1 without adding polyphenols and Comparative Example 4 without adding metal ions, the effect of inhibiting weight gain is poor. (4) Hypoglycemic effect Five-week-old C57BL / 6J male mice were selected and raised in an SPF mouse house (room temperature 25±2°C, relative humidity 45%-65%, 12h day and night light and dark alternation). After 7 days of adaptive feeding, they were weighed (initial weight of the experiment) and randomly divided into 6 groups, 12 mice in each group, 4 mice / cage for feeding, and high-fat diet (60% kcal, D12492; Research Diets). The blank group was gavaged with normal saline; the rest were gavaged with Example 6 and Comparative Examples 1-4 plant oils (100 mg / kg mouse body weight). After gavage for 12 weeks until the end of the experiment, after fasting for 6 hours, the mice were taken out of the cage, gently placed on the experimental table, and the mouse eyeballs were removed with sterilized tweezers to collect blood. After collecting the mouse blood, it was left to stand at room temperature for 30 minutes, centrifuged at 3000×g for 15 minutes, and then packaged and stored for use. The blood glucose content was determined according to the instructions of the ELISA kit. Depend on Figure 4 It can be seen that a high-fat diet can increase the fasting blood sugar level of mice, but the intervention of Example 6 shows a controlling effect on blood sugar, which shows that the preparation method of the present invention has a significant inhibitory effect on the increase in blood sugar caused by obesity; the blood sugar trends of the oils prepared in Comparative Example 1 without adding polyphenols and Comparative Example 2 without adding carotenoids are similar; Comparative Example 3 without adding gallic acid and Comparative Example 4 without adding metal ions, the effect of inhibiting blood sugar growth is poor. The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for improving the oxidative stability of vegetable oils and fats, characterized in that: The following steps are involved: S1. Adding polyphenols, carotenoids and gallic acid to vegetable oils and fats, emulsifying, and obtaining a mixed oil solution; S2. Add a stabilizer and a crystallization inhibitor to the mixed oil solution, stir evenly, let stand, and filter to obtain a transparent oil solution; S3. Add ferric sulfate solution and copper sulfate solution to the transparent oil solution, react at 120-150°C for 8-10 hours, and stir evenly to obtain vegetable oil with high oxidation stability.

2. A method for improving the oxidative stability of vegetable oils according to claim 1, characterized in that: The vegetable oils in step S1 include tomato seed oil, passion fruit seed oil, melon oil and garlic fruit oil; the polyphenols include vanillic acid, quercetin, curcumin and oil-soluble tea polyphenols.

3. A method for improving the oxidative stability of vegetable oils according to claim 1, characterized in that: In step S1, the mass volume ratio of polyphenols to vegetable oils is 1:(100-200); the mass volume ratio of polyphenols to carotenoids and gallic acid is 1:(0.8-1.2):(0.05-0.1).

4. A method for improving the oxidative stability of vegetable oils according to claim 1, characterized in that: The emulsification condition in step S1 is stirring at a temperature of 70-120° C. for 20-40 minutes.

5. The method for improving the oxidative stability of vegetable oils according to claim 1, characterized in that: In step S2, the stabilizer is glycerol or sorbitol; and the crystallization inhibitor is Tween, phospholipid or sucrose fatty acid ester.

6. A method for improving the oxidative stability of vegetable oils according to claim 1, characterized in that: The mass ratio of the polyphenol, the stabilizer and the crystallization inhibitor is 1:(0.5-2.5):(0.02-2).

7. The method for improving the oxidative stability of vegetable oils according to claim 1, characterized in that: In step S2, the stirring speed is 300-600 r / min, and the stirring time is 30-60 min.

8. The method for improving the oxidative stability of vegetable oils according to claim 1, characterized in that: The iron ion content in the ferric sulfate solution in step S3 is 0.0005-0.001 ppm; the copper ion content in the copper sulfate solution is 0.0002-0.0008 ppm.

9. The vegetable oil with high oxidation stability obtained by the method according to any one of claims 1 to 8.

10. Use of the high oxidative stability vegetable oil according to claim 9 in blood sugar and lipid lowering products.

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