Method for improving oxidation resistance of edible oil

Abstract

The invention discloses a method for improving oxidation resistance of edible oil, and belongs to the technical field of edible oil processing. The preparation method comprises the following steps: mixing phospholipid, cholesterol, a natural plant source antioxidant and an organic solvent according to a weight part ratio of (5-10): (1-3): (1-2): (500-1000), dispersing to form a mixture, and carrying out rotary evaporation on the mixture to obtain a liposome film; mixing and hydrating the liposome film and water according to the weight part ratio of 1: (100-200) to obtain liposome dispersion liquid; carrying out freeze-drying treatment on the liposome dispersion liquid to obtain a liposome antioxidant; the liposome antioxidant and the edible oil are mixed and stirred according to the weight part ratio of (0.001-0.003): 1 to finish the antioxidant treatment of the edible oil. The natural plant source antioxidant is prepared into the lipidosome, the lipidosome antioxidant with good stability and high antioxidant activity is obtained, the oxidation resistance of the lipidosome antioxidant in the edible oil is further improved, and the oxidation stability of the edible oil can be effectively improved by adding the lipidosome antioxidant into the edible oil.

Description

Technical Field

[0001] This invention belongs to the field of edible oil processing technology, and specifically relates to a method for improving the antioxidant properties of edible oil. Background Technology

[0002] Edible oil, as an indispensable nutrient and cooking ingredient in daily life, directly affects people's dietary health and quality of life. Currently, edible oils on the market can be divided into plant-based and animal-based oils based on their raw material source, with plant-based oils dominating due to their abundant resources and balanced nutrition. Common plant-based oils include sesame oil, olive oil, soybean oil, peanut oil, rapeseed oil, corn oil, and sunflower oil. Different types of plant-based oils exhibit significant differences in fatty acid composition and nutritional components. With the rapid development of the food industry and the increasing health awareness of consumers, their nutritional characteristics and processing techniques have received widespread attention. At the same time, the oxidative deterioration of edible oils during production, storage, transportation, and use has become a key factor restricting their quality stability and shelf life. Oxidative deterioration of edible oil is a complex chemical process, caused by numerous factors, mainly including internal and external factors. Internal factors primarily concern the fatty acid composition of the edible oil; the higher the content of unsaturated fatty acids, the worse the oxidative stability of the edible oil. Because unsaturated fatty acid molecules contain double bonds, the presence of these double bonds makes the molecular structure unstable and susceptible to attack by free radicals, triggering oxidation reactions. For example, edible oils rich in unsaturated fatty acids, such as sesame oil, olive oil, and flaxseed oil, have relatively low oxidative stability and are more prone to oxidative deterioration. External factors mainly include light, temperature, oxygen, metal ions, and moisture. Light, especially ultraviolet light, can accelerate the oxidative decomposition of unsaturated fatty acids in edible oils; increased temperature significantly accelerates the rate of oxidation reactions, and the rate of oxidative deterioration of edible oils increases dramatically under high-temperature conditions, so temperature control is necessary during the storage and processing of edible oils; oxygen is a necessary condition for the oxidation reaction of edible oils, and the higher the oxygen concentration, the easier the oxidation reaction occurs, so edible oil packaging needs to be well-sealed to reduce contact with air; metal ions (such as iron and copper) have a catalytic effect and can accelerate the oxidation reaction, so the production equipment and storage containers for edible oils should avoid using metal materials that are prone to rusting; excessive moisture content promotes hydrolysis and oxidation reactions in edible oils and may also breed microorganisms, accelerating the deterioration of edible oils, so moisture content needs to be strictly controlled during the production process of edible oils. When cooking oil oxidizes and deteriorates, it not only affects its sensory quality (such as developing a rancid smell or darkening its color), but also reduces its nutritional value and may even produce harmful substances that endanger human health. From a nutritional perspective, during the oxidation process, unsaturated fatty acids are destroyed, the content of essential fatty acids decreases, and natural antioxidants such as vitamin E are depleted, leading to a significant decline in the nutritional value of the cooking oil.From a health perspective, the small molecule compounds such as aldehydes, ketones, and acids produced by the oxidation and decomposition of edible oils are toxic. Long-term consumption of spoiled edible oils can lead to the accumulation of these harmful substances in the body, damaging organs such as the liver and kidneys. It can also trigger inflammatory responses and oxidative stress, increasing the risk of cardiovascular disease, cancer, and other chronic diseases. Furthermore, oxidized and spoiled edible oils may produce peroxides, which are highly oxidizing and can damage cell membranes, affecting normal cellular functions and accelerating aging. For food processing companies, the oxidation and spoilage of edible oils can lead to unstable product quality, shortened shelf life, increased production costs, and even product quality disputes. Therefore, taking effective antioxidant measures to improve the oxidative stability of edible oils, extend their shelf life, and ensure their quality and safety is of significant economic and social importance. The content of natural antioxidants (such as vitamin E, phytosterols, and polyphenols) in edible oils also affects their oxidative stability; the higher the content of natural antioxidants, the stronger the oil's own antioxidant capacity and the slower the rate of oxidation and spoilage. However, due to the processing methods, these natural antioxidants are often present in low concentrations in edible oils, making it difficult for them to exert a good antioxidant effect.

[0003] To address the problem of oxidative deterioration in edible oils, extensive research has been conducted both domestically and internationally, resulting in the development of various antioxidant technologies, primarily categorized into physical and chemical antioxidants. Physical antioxidants mainly slow down oxidative deterioration by controlling storage conditions (such as light protection, low temperature, airtight sealing, and vacuum packaging), using antioxidant packaging materials (such as barrier-resistant plastic and glass packaging), and adding inert gases (such as nitrogen and carbon dioxide). These methods reduce the contact between edible oils and oxidizing factors like oxygen, light, and temperature. Physical antioxidants offer advantages such as safety and lack of pollution, but they require specific storage and transportation conditions, have limited antioxidant effects, and are insufficient for large-scale production and long-term storage. Chemical antioxidants are currently the most widely used edible oil antioxidant technology, primarily inhibiting oxidation by adding chemically synthesized antioxidants. Commonly used chemically synthesized antioxidants include butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), and propyl gallate. These chemically synthesized antioxidants have advantages such as good antioxidant effect, low cost, and small addition amount, and can effectively delay the oxidative deterioration of edible oils and extend their shelf life. However, with the continuous improvement of consumers' health awareness, the safety issues of chemically synthesized antioxidants have gradually attracted attention, and they do not meet the demand for natural and healthy foods. Therefore, many countries and regions have imposed strict restrictions on the use of chemically synthesized antioxidants.

[0004] Against this backdrop, natural plant-derived antioxidants have become a research hotspot in the field of edible oil antioxidants due to their wide availability, high safety, and good antioxidant effects. Natural plant-derived antioxidants refer to substances with antioxidant activity extracted from plants, mainly including polyphenols (such as tea polyphenols, grape seed extract, olive leaf extract, etc.), flavonoids (such as rutin, quercetin, etc.), vitamins (such as vitamin E, vitamin C, etc.), and phytosterols. These natural plant-derived antioxidants not only have good antioxidant effects, effectively scavenging free radicals and inhibiting the oxidation reaction of edible oils, but also have certain health benefits, meeting consumers' demand for natural and healthy foods. Therefore, how to utilize natural plant-derived antioxidants to improve the antioxidant properties of edible oils has significant market value for improving the quality, safety, and extending the shelf life of edible oils. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for improving the antioxidant properties of edible oils. This method involves preparing natural plant-derived antioxidants into liposomes, obtaining liposomal antioxidants with good stability and high antioxidant activity, thereby enhancing their antioxidant properties in edible oils. Adding these liposomal antioxidants to edible oils effectively improves the oxidative stability of the oils, thus solving the technical problems mentioned in the background art. Specifically, the technical solution of this invention includes the following: A method for improving the antioxidant properties of edible oils, the method comprising the following steps: Phospholipids, cholesterol, natural plant-derived antioxidants, and organic solvents are mixed and dispersed in a weight ratio of 5~10:1~3:1~2:500~1000 to form a mixture, and the mixture is then subjected to rotary evaporation to obtain a liposome film. A liposome dispersion is obtained by hydrating a liposome membrane and water at a weight ratio of 1:100~200. Liposome antioxidants were obtained by freeze-drying liposome dispersions. The antioxidant liposomes and edible oils were mixed and stirred at a weight ratio of 0.001 to 0.003:1 to complete the antioxidant treatment of the edible oils.

[0006] Furthermore, the phospholipids include soybean lecithin or egg yolk lecithin.

[0007] Furthermore, the natural plant-derived antioxidants include green tea extract, grape seed extract, or rosemary extract.

[0008] Furthermore, the preparation method of the tea extract includes the following steps: Green tea leaves and a 70% ethanol solution were mixed at a ratio of 1g:15mL and then heated to 70℃ for 2 hours to extract the first filtrate and filter residue. The filter residue and a 70% ethanol solution were mixed at a material-to-liquid ratio of 1g:10mL and then heated to 70℃ for 1 hour to obtain the second filtrate. The tea extract was obtained by purifying the first and second filtrates.

[0009] Furthermore, the preparation method of the grape seed extract includes the following steps: Grape seeds and an 80% ethanol solution were mixed at a ratio of 1g:20mL and then heated to 80℃ for 4 hours to extract the first filtrate and the residue. The filter residue and an 80% ethanol solution were mixed at a material-to-liquid ratio of 1g:10mL and then heated to 80℃ for 1 hour to obtain the second filtrate. The first and second filtrates were combined and purified to obtain the grape seed extract.

[0010] Furthermore, the preparation method of the rosemary extract includes the following steps: Rosemary and a 60% ethanol solution were mixed at a ratio of 1g:10mL and then heated to 60℃ for 3 hours to extract the first filtrate and the residue. The filter residue and a 60% ethanol solution were mixed at a material-to-liquid ratio of 1g:10mL and then heated to 60℃ for 2 hours to obtain the second filtrate. The first and second filtrates were combined and purified to obtain the rosemary extract.

[0011] Furthermore, the organic solvent includes chloroform or methanol.

[0012] Furthermore, the conditions for mixing and dispersing include an ultrasonic power of 200W~300W and a dispersion time of 15min~20min.

[0013] Furthermore, the conditions for rotary evaporation include a rotary evaporation temperature of 40℃~45℃, a vacuum degree of 0.08MPa, and a rotary evaporation speed of 60r / min.

[0014] Furthermore, the mixing and hydration process includes stirring at 100r / min to 150r / min at 40℃ to 45℃ for 60min to 70min, followed by dispersion treatment in 300W ultrasonic power for 2min to 3min.

[0015] Furthermore, the freeze-drying process includes freezing at -40°C for 5 hours, freezing at -30°C for 20 hours, and finally drying at 25°C for 10 hours.

[0016] Furthermore, the edible oil includes sunflower seed oil, but may also be rapeseed oil or flaxseed oil.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes active ingredients with antioxidant functions extracted from plants as natural plant-derived antioxidants to exert their antioxidant effects. Subsequently, liposomes composed of phospholipids and cholesterol are used. Oil-soluble antioxidants can be encapsulated in the water-carrying tail of the phospholipid bilayer through the interaction of hydrophobic regions, while water-soluble antioxidants are encapsulated in the aqueous phase by forming hydrogen bonds with the hydrophilic phosphate groups of the phospholipid head. The amphiphilic nature of liposome antioxidants allows them to encapsulate both oil-soluble and water-soluble antioxidants, providing a wide encapsulation range. Furthermore, the amphiphilic nature of liposome antioxidants ensures good dispersibility in the lipid phase environment of edible oils, preventing the formation of particles due to polarity mismatch and thus maintaining the clarity and transparency of the edible oil. By encapsulating edible oils with liposomes, the antioxidant duration is extended, which not only helps to extend the shelf life of edible oils but also avoids the use of chemically synthesized antioxidants, making it green and safe, and meeting consumers' demand for natural and healthy foods. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available or can be prepared by known methods.

[0020] Preparation Example 1 The preparation method of tea extract is as follows: After rinsing the green tea leaves, dry them at 50℃ to constant weight. Then, pulverize them using a grinder and pass them through a 40-mesh sieve. Next, weigh 100g of green tea leaves and mix them with 1.5L of 70% ethanol solution. Stir well and then heat to 70℃ for reflux extraction for 2 hours. After extraction, filter to separate the first filtrate and the residue. Then, add 70% ethanol solution to the residue at a material-to-liquid ratio of 1g:10mL, mix well, and heat to 70℃ for reflux extraction for 1 hour. After extraction, filter to separate the second filtrate. Combine the first and second filtrates and purify them using macroporous resin. The loading concentration is controlled at 0.8mg / mL, the loading flow rate is 1.5 BV / h, and the elution is performed using 70% ethanol solution at a flow rate of 1.5 BV / h. Collect the eluent and remove the ethanol by vacuum concentration to obtain the tea extract.

[0021] Preparation Example 2 The preparation method of grape seed extract is as follows: After washing the grape seeds, they were dried at 50℃ to constant weight, then pulverized using a grinder and passed through a 40-mesh sieve. 100g of grape seeds were weighed and mixed thoroughly with 2L of 80% ethanol solution. The mixture was then heated to 80℃ and refluxed for 4 hours. After extraction, the first filtrate and residue were separated by filtration. Next, at a material-to-liquid ratio of 1g:10mL, 80% ethanol solution was added to the residue and mixed thoroughly. The mixture was then heated to 80℃ and refluxed for 1 hour. After extraction, the second filtrate was separated by filtration. The first and second filtrates were combined and purified using a macroporous resin at a loading concentration of 1mg / mL and a loading flow rate of 2BV / h. An 80% ethanol solution was used as the eluting agent at a flow rate of 2BV / h. The eluent was collected and concentrated under reduced pressure to remove the ethanol, yielding the grape seed extract.

[0022] Preparation Example 3 The preparation method of rosemary extract is as follows: After washing the rosemary, dry it at 50℃ to constant weight, then pulverize it using a grinder and pass it through a 40-mesh sieve. Next, weigh 100g of rosemary and mix it with 1L of 60% ethanol solution. Heat to 60℃ and reflux for 3 hours. After extraction, filter to obtain the first filtrate and residue. Then, add 60% ethanol solution to the residue at a material-to-liquid ratio of 1g:10mL, mix well, and heat to 60℃ and reflux for 2 hours. After extraction, filter to obtain the second filtrate. Combine the first and second filtrates and purify them using a macroporous resin. The loading concentration is controlled at 0.5mg / mL, the loading flow rate is 1 BV / h, and the elution is performed using 60% ethanol solution at a flow rate of 1 BV / h. Collect the eluent and concentrate under reduced pressure to remove ethanol, obtaining the rosemary extract.

[0023] Example 1

[0024] A method for improving the antioxidant properties of edible oils includes the following steps: Five parts by weight of soybean lecithin and one part by weight of cholesterol were dissolved in 500 parts by weight of chloroform. One part by weight of the tea extract obtained in Preparation Example 1 was then added. The mixture was placed in an ultrasonic disperser, and the ultrasonic power was adjusted to 200 W for 15 min. After uniform ultrasonic dispersion, the mixture was transferred to a rotary evaporator. The rotation speed was controlled at 60 r / min, the rotation temperature at 40 °C, and the vacuum degree at 0.08 MPa. Chloroform was removed by rotary evaporation until a uniform liposome film was formed. Deionized water was added to the liposome film at a weight ratio of 1:100. The film was then hydrated at 40 °C and a rotation speed of 100 r / min for 60 min. Finally, it was ultrasonically treated with an ultrasonic power of 300 W for 2 min. The liposome dispersion was obtained; the particle size of the liposomes in the dispersion was determined by dynamic light scattering method, and the result showed that the particle size was 200.5 nm; the liposome dispersion was placed in a freeze dryer, first frozen at -40℃ for 5 h, then frozen at -30℃ for 20 h, and finally dried at 25℃ for 10 h to obtain liposome antioxidants. The liposome antioxidants were added to sunflower seed oil at a ratio of 0.1% of the mass of sunflower seed oil, and stirred at 100 r / min for 15 min at 28℃ to complete the antioxidant treatment of edible oil.

[0025] Example 2

[0026] A method for improving the antioxidant properties of edible oils includes the following steps: Eight parts by weight of soybean lecithin and two parts by weight of cholesterol were dissolved in 800 parts by weight of chloroform. One part by weight of grape seed extract obtained in Preparation Example 2 was then added. The mixture was placed in an ultrasonic disperser, and the ultrasonic power was adjusted to 300 W for 15 min. After uniform ultrasonic dispersion, the mixture was transferred to a rotary evaporator. The rotation speed was controlled at 60 r / min, the rotation temperature at 40 °C, and the vacuum degree at 0.08 MPa. Chloroform was removed by rotary evaporation until a uniform liposome film was formed. Deionized water was added to the liposome film at a weight ratio of 1:100. The film was then hydrated at 40 °C and a rotation speed of 100 r / min for 70 min. Finally, it was ultrasonically treated with an ultrasonic power of 300 W for 2 min. The liposome dispersion was obtained; the particle size of the liposomes in the dispersion was determined by dynamic light scattering, and the result showed that the particle size was 211.2 nm; the liposome dispersion was placed in a freeze dryer, first frozen at -40℃ for 5 h, then frozen at -30℃ for 20 h, and finally dried at 25℃ for 10 h to obtain liposome antioxidants. The liposome antioxidants were added to sunflower seed oil at a ratio of 0.2% of the mass of sunflower seed oil, and stirred at 100 r / min for 15 min at 28℃ to complete the antioxidant treatment of the edible oil.

[0027] Example 3

[0028] A method for improving the antioxidant properties of edible oils includes the following steps: Ten parts by weight of egg yolk lecithin and three parts by weight of cholesterol were dissolved in 1000 parts by weight of methanol. Two parts by weight of rosemary extract obtained in Preparation Example 3 were then added. The mixture was placed in an ultrasonic disperser, and the ultrasonic power was adjusted to 300 W for 20 min. After uniform ultrasonic dispersion, the mixture was transferred to a rotary evaporator. The rotation speed was controlled at 60 r / min, the rotation temperature at 45 °C, and the vacuum degree at 0.08 MPa. Methanol was removed by rotary evaporation until a uniform liposome film was formed. Deionized water was added to the liposome film at a weight ratio of 1:100. The film was then hydrated at 45 °C and a rotation speed of 150 r / min for 70 min. Finally, it was ultrasonically treated with an ultrasonic power of 300 W for 3 min. The liposome dispersion was obtained; the particle size of the liposomes in the dispersion was determined by dynamic light scattering, and the result showed that the particle size was 192.6 nm; the liposome dispersion was placed in a freeze dryer, first frozen at -40℃ for 5 h, then frozen at -30℃ for 20 h, and finally dried at 25℃ for 10 h to obtain liposome antioxidants. The liposome antioxidants were added to sunflower seed oil at a ratio of 0.3% of the mass of sunflower seed oil, and stirred at 100 r / min for 15 min at 28℃ to complete the antioxidant treatment of the edible oil.

[0029] Antioxidant stability test: Edible oils that underwent antioxidant treatment in Examples 1-3 were placed in a constant temperature chamber at 50±1℃. Samples were taken every two days to measure the peroxide value. The peroxide value was determined according to the colorimetric method in GB / T 5009.37-2003. Edible oils without added liposome antioxidants were used as a control group. The lower the peroxide value, the better the oxidative stability of the edible oil. The test results are shown in Table 1 below. Table 1 Peroxide Value Source of materials Day 2 peroxide value (meq / kg) Day 4 peroxide value (meq / kg) Day 6 peroxide value (meq / kg) Peroxide value on day 8 (meq / kg) Example 1 6.8 7.2 9.4 10.3 Example 2 6.5 6.8 8.1 8.6 Example 3 6.1 6.2 6.2 6.5 Sunflower seed oil (without added liposome antioxidants) 9.2 18.6 37.4 50.7 The test results above show that the peroxide values ​​of the edible oils treated with antioxidants in Examples 1-3 were significantly lower than those in the control group after 8 days of storage, indicating that the method of the present invention can effectively improve the oxidative stability of edible oils and extend their shelf life.

[0030] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for improving the antioxidant properties of edible oils, characterized in that, The method includes the following steps: Phospholipids, cholesterol, natural plant-derived antioxidants, and organic solvents are mixed and dispersed in a weight ratio of 5~10:1~3:1~2:500~1000 to form a mixture, and the mixture is then subjected to rotary evaporation to obtain a liposome film. A liposome dispersion is obtained by hydrating a liposome membrane and water at a weight ratio of 1:100~200. Liposome antioxidants were obtained by freeze-drying liposome dispersions. The antioxidant liposomes and edible oils were mixed and stirred at a weight ratio of 0.001 to 0.003:1 to complete the antioxidant treatment of the edible oils.

2. The method for improving the antioxidant properties of edible oil according to claim 1, characterized in that, The phospholipids include soybean lecithin or egg yolk lecithin.

3. The method for improving the antioxidant properties of edible oil according to claim 1, characterized in that, The natural plant-derived antioxidants include tea extract, grape seed extract, or rosemary extract.

4. The method for improving the antioxidant properties of edible oil according to claim 1, characterized in that, The organic solvent includes chloroform or methanol.

5. The method for improving the antioxidant properties of edible oil according to claim 1, characterized in that, The conditions for mixing and dispersing include an ultrasonic power of 200W~300W and a dispersion time of 15min~20min.

6. The method for improving the antioxidant properties of edible oil according to claim 1, characterized in that, The conditions for rotary evaporation include a rotary evaporation temperature of 40℃~45℃, a vacuum degree of 0.08MPa, and a rotary evaporation speed of 60r / min.

7. The method for improving the antioxidant properties of edible oil according to claim 1, characterized in that, The mixing and hydration process includes stirring at 100r / min to 150r / min in 40℃ to 45℃ for 60min to 70min, followed by dispersion treatment in 300W ultrasonic power for 2min to 3min.

8. The method for improving the antioxidant properties of edible oil according to claim 1, characterized in that, The freeze-drying process includes freezing at -40°C for 5 hours, freezing at -30°C for 20 hours, and finally drying at 25°C for 10 hours.

9. The method for improving the antioxidant properties of edible oil according to claim 1, characterized in that, The edible oils include sunflower seed oil.