Synergistic composition for protecting oxidation stability of walnut kernel grease and preparation method thereof

Abstract

The invention discloses a synergistic composition for protecting the oxidation stability of walnut kernel grease and a preparation method of the synergistic composition. An anti-oxidation synergist and an anti-oxidation molecular chaperone are added into walnut oil; the stability of the walnut oil is improved by utilizing adsorption and dispersion of modified ascorbate on a grease interface, synergistic regeneration of an antioxidant molecular chaperone and solvation of an antioxidant synergist in grease, the biological activity of the walnut oil is not influenced, and meanwhile, the preparation method is simple, convenient and effective.

Description

Technical Field

[0001] The present invention belongs to the technical fields of chemistry, fine chemical engineering, and biological medicine, and specifically relates to a synergistic composition for protecting the oxidative stability of walnut kernel oil and a preparation method thereof. Background Art

[0002] Walnut oil is extracted from walnuts and contains most of the nutritional, health-care, and pharmacological active ingredients of walnut kernels. As the most common problem of walnut oil, the oxidation process not only affects the flavor of the oil but also produces toxic lipid degradation by-products, such as aldehydes, ketones, acids, and other substances.

[0003] Unsaturated fatty acids in oils will slowly absorb oxygen and oxidize and deteriorate under general storage conditions, thereby affecting the product quality and wide applications in various fields. Oxidative stability can predict and evaluate the possible oxidative rancidity of oils, so as to control the flavor of oils and predict the shelf life of oils. Therefore, improving the oxidative stability of walnut oil is one of the feasible methods to extend its shelf life. Researchers have applied various technologies to improve the oxidative stability of walnut oil, including oil encapsulation, adding antioxidants, and changing the extraction process. In 2019, Yu Xuya et al. effectively slowed down the oxidation rate of walnut oil by adding TBHQ and the optimal proportion of astaxanthin oil to the walnut oil to be stored, taking advantage of the strong antioxidant property of astaxanthin oil. In 2012, Zhao Liangqi et al. prepared antioxidant-functional walnut oil soft capsules using walnut oil, flavonoids, and soy lecithin as raw materials and edible beeswax as a suspending agent. In 2021, Yu Xiuzhu et al. added an antioxidant coating and a one-way check valve to the oil packaging, making the oil in the package "only out and not in", effectively reducing the chance of the oil in the package contacting with air, and the internal antioxidant coating can continuously release antioxidants during the storage of the oil to further delay the oxidation of the oil. In 2024, Fabrice Tonfack Djikeng et al. mixed African walnut oil with palm oil, peanut oil, and more stable avocado oil to extend its shelf life. However, the above synthetic antioxidants have potential safety hazards and do not conform to the "clean label" trend. Single natural antioxidants (such as carnosic acid) are costly, have poor solubility, and may fail at high temperatures.

[0004] In the prior art, the main methods for improving the oxidative stability of walnut oil are as follows: (1) Adding antioxidants. High-efficiency antioxidants can effectively improve the oxidative stability of oils and fats for a certain period of time. However, they may pose potential hazards to human health or affect the product. For example, butylated hydroxyanisole (BHA) and dibutylhydroxytoluene (BHT) are allowed to be used within the specified dosage. However, studies have shown that long-term or excessive intake may have a carcinogenic risk. Another example is that tert-butylhydroquinone (TBHQ) can improve the antioxidant effect of walnut oil, but it may inhibit the activity of immune cells and affect the normal function of the immune system, resulting in immunosuppression. If the addition amount of propyl gallate (PG) is too much, it may change the flavor of the oil and make it have a faint bitter taste. Some antioxidants may change the color of the oil during the process of exerting their effects, making it darker or producing other changes, affecting the appearance quality of the oil; (2) Physical modification methods. By forms such as vacuum packaging and secondary packaging to isolate oxygen in the environment, the oxidative stability of walnut oil can be delayed. This method makes the production process complex and increases the production cost during production; (3) Refining treatment. By refining treatment, various impurities in walnut oil are removed, including free fatty acids, pigments, and odor substances that may promote oxidation. However, during the refining process, some beneficial nutrients may be lost, such as some vitamins and bioactive substances. In addition, the refining process involves inputs in multiple aspects such as equipment, energy, and chemical reagents, which will increase the production cost, and the equipment and process are complex and require professional operators.

[0005] There are few current research technologies on methods for improving the oxidative stability of walnut oil with low cost, naturalness, and high efficiency. Summary of the Invention

[0006] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions cannot be used to limit the scope of the present invention.

[0007] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a synergistic composition for protecting the oxidative stability of walnut kernel oil.

[0009] To solve the above technical problems, the present invention provides the following technical solution: A synergistic composition for protecting the oxidative stability of walnut kernel oil, including,

[0010] Antioxidant molecular chaperone, antioxidant synergist and solvent; wherein, the mass ratio of the antioxidant molecular chaperone, the antioxidant synergist and the solvent is 0.20 - 0.80:0.01 - 0.05:2.60 - 3.50, and the antioxidant molecular chaperone is composed of modified ascorbate and tocopherol, and the mass ratio range of the modified ascorbate to tocopherol is 5:5 - 7:3 wt%.

[0011] As a preferred embodiment of the synergistic composition of the present invention, wherein: the antioxidant synergist is one or more of ferulic acid, chlorogenic acid, carnosic acid, propyl gallate.

[0012] As a preferred embodiment of the synergistic composition of the present invention, wherein: the solvent is 1,2-pentanediol or absolute ethanol.

[0013] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of a synergistic composition in improving the oxidative stability of walnut oil, including dissolving modified ascorbate and tocopherol in a solvent by ultrasonic treatment to obtain a homogeneous phase A;

[0014] Adding an antioxidant synergist to the walnut oil as phase B;

[0015] Mixing phases A and B evenly and dissolving them by ultrasonic treatment to obtain a molecular composition that can naturally and long-lastingly protect the oxidative stability of walnut oil.

[0016] As a preferred embodiment of the application of the present invention, wherein: the walnut oil variety is one or more of Paohu walnut oil, Tie walnut oil, Gaofashan walnut oil, Dapao walnut oil, and water-extracted walnut oil.

[0017] As a preferred embodiment of the application of the present invention, wherein: calculated by mass percentage of the raw materials, the content of the antioxidant molecular chaperone is 0.20 - 0.80%, the content of the antioxidant synergist is 0.01 - 0.05%, the content of the solvent is 2.60 - 3.50%, and the content of the walnut oil is 98.00 - 100.00%.

[0018] Advantages of the present invention:

[0019] By adding an antioxidant synergist and an antioxidant molecular chaperone to walnut oil, the present invention utilizes the adsorption and dispersion of modified ascorbate at the oil-gas interface, the synergistic regeneration of the antioxidant molecular chaperone, and the solvation effect of the antioxidant synergist in the oil, thereby improving the stability of walnut oil itself, without affecting the biological activity of walnut oil itself, and at the same time the preparation method is simple and effective. Description of the Drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings. Among them:

[0021] Figure 1 It is a graph of the time required for the walnut oil in the embodiment of the present invention to accelerate aging to exceed the national standard and its peroxide value.

[0022] Figure 2 It is a graph of the time required for the walnut oil in the comparative example of the present invention to accelerate aging to exceed the national standard and its peroxide value. Detailed implementation manners

[0023] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will make a detailed description of the specific implementation manners of the present invention in combination with the embodiments of the specification.

[0024] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0025] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0026] Glossary of terms in the present invention

[0027] ① Oxidative stability of walnut oil: It refers to the ability of oil to resist auto-oxidation, which reflects the storage stability of oil.

[0028] ② Peroxide value of walnut oil: The peroxide value (POV) reflects the degree of primary oxidation products, especially in the initial stage of lipid oxidation. A large number of peroxides and hydroperoxides will be formed in the oil during the oxidation and degradation of the oil. Therefore, POV measurement can be used to describe the degree to which antioxidants inhibit these oxidation products.

[0029] ③ Antioxidant molecular chaperone: Modified ascorbate and tocopherol are a pair of redox pairs that play an antioxidant role. When ascorbyl palmitate binds to tocopherol, the latter first reacts with free radicals to produce tocopherol radicals. Tocopherol can be regenerated in the presence of ascorbyl palmitate.

[0030] ④ Shelf life: Also known as the expiration date or the packaging validity period; in addition, appropriate circulation and storage conditions such as temperature and humidity are also specified.

[0031] For the types, grades, and sources of the test samples in the embodiments of the present invention, refer to Table 1.

[0032] Table 1

[0033]

[0034]

[0035] Example 1

[0036] Dissolve 0.12 g of L-ascorbyl palmitate and 0.12 g of δ-tocopherol in 1 g of anhydrous ethanol by stirring and ultrasonic dissolution to obtain a uniform Phase A;

[0037] Meanwhile, add 0.015 g of chlorogenic acid to 30 g of pecan oil as Phase B;

[0038] Subsequently, mix Phases A and B evenly to obtain a composite system for protecting the oxidation stability of pecan oil.

[0039] Using the iron pecan oil itself without adding any samples as a control after accelerating aging for 8 h in an ultraviolet film oven at a high temperature (60 °C), an air flow rate of 20 L / h, and ultraviolet light irradiation, investigate the relative protection rate of the pecan oil after adding the protective agent.

[0040] The experimental results are shown in Table 2, Figure 1 as shown.

[0041] As can be seen from Table 2, compared with the control, the shelf life of the pecan oil after adding the protective agent is extended to 2.5 years, that is, the oxidation stability of the pecan oil is greatly increased.

[0042] Example 2

[0043] Dissolve 0.12 g of L-ascorbyl palmitate and 0.12 g of β-tocopherol in 1 g of 1,2-pentanediol by stirring and ultrasonic dissolution to obtain a uniform Phase A;

[0044] Meanwhile, add 0.015 g of ferulic acid to 30 g of pecan oil as Phase B;

[0045] Subsequently, mix Phases A and B evenly to obtain a composite system for protecting the oxidation stability of pecan oil.

[0046] Using the iron pecan oil itself without adding any samples as a control after accelerating aging in an ultraviolet film oven at a high temperature (60 °C), an air flow rate of 20 L / h, and ultraviolet light irradiation, investigate the relative protection rate of the pecan oil after adding the protective agent. The experimental results are shown in Table 2,Figure 1 as shown

[0047] As can be seen from Table 2, compared with the control, the shelf life of walnut oil is extended to 2 years after adding the protective agent, that is, the oxidation stability of walnut oil is greatly increased.

[0048] Example 3

[0049] Dissolve 0.12 g of L-ascorbyl palmitate and 0.12 g of α-tocopherol in 1 g of absolute ethanol by stirring and ultrasonic dissolution to obtain a homogeneous Phase A;

[0050] Meanwhile, add 0.015 g of carnosic acid to 30 g of hickory nut oil as Phase B;

[0051] Subsequently, mix Phase A and Phase B evenly to obtain a composite system for protecting the oxidation stability of walnut oil;

[0052] Using the walnut oil itself without adding any samples as the control after accelerated aging in an ultraviolet thin-film oven at high temperature (60 °C), air flow rate of 20 L / h, and ultraviolet light irradiation, the relative protection rate of walnut oil after adding the protective agent was investigated. The experimental results are shown in Table 2, Figure 1 as shown

[0053] As can be seen from Table 2, compared with the control, the shelf life of walnut oil is extended to 5.25 years after adding the protective agent, that is, the oxidation stability of walnut oil is greatly increased.

[0054] Example 4

[0055] Dissolve 0.12 g of L-ascorbyl palmitate and 0.12 g of α-tocopherol in 1 g of absolute ethanol by stirring and ultrasonic dissolution to obtain a homogeneous Phase A;

[0056] Meanwhile, add 0.015 g of propyl gallate to 30 g of hickory nut oil as Phase B;

[0057] Subsequently, mix Phase A and Phase B evenly to obtain a composite system for protecting the oxidation stability of walnut oil.

[0058] Using the iron walnut oil itself without adding any samples as the control after accelerated aging in an ultraviolet thin-film oven at high temperature (60 °C), air flow rate of 20 L / h, and ultraviolet light irradiation, the relative protection rate of walnut oil after adding the protective agent was investigated. The experimental results are shown in Table 2, Figure 1 as shown

[0059] As can be seen from Table 2, compared with the control, the shelf life of walnut oil is extended to 4.25 years after adding the protective agent, that is, the oxidation stability of walnut oil is greatly increased.

[0060] Shelf life conversion:

[0061] Regarding the system for improving the stability of walnut oil, the stabilities of the walnut oils in Examples 1-4 were studied respectively. Taking the pecan oil without adding any substances as a control, accelerated aging was carried out in an ultraviolet thin-film oven under high temperature (60 °C), an air flow rate of 20 L / h, and ultraviolet light irradiation. Samples were taken regularly to measure the peroxide value of the walnut oil. The results are as Figure 1 shown.

[0062] Record the time required for accelerated aging until the peroxide value exceeds the value required by the national standard for cosmetics. Taking the time required for commercially available walnut oil with a known shelf life as a control, calculate the shelf life after the fine processing of the walnut oil. The results are shown in Table 2.

[0063] Table 2 Time required for pecan oil to accelerate aging to exceed the national standard under different systems

[0064]

[0065] Example 5

[0066] Interface adsorption effect of modified ascorbate on oil:

[0067] Prepare a series of L-ascorbyl palmitate-pecan oil solutions with different concentrations, ultrasonicate them for 10 min at 60 °C to make them uniformly dispersed, and measure their surface tensions at 60 °C using the platinum plate method to obtain Table 3.

[0068] Table 3 L-ascorbyl palmitate-pecan oil (60 °C)

[0069]

[0070] As can be seen from Table 3, as the addition amount of L-ascorbyl palmitate increases, the surface tension of the oil decreases from 24.99 mM / m when the addition amount is 0.1% to 19.91 mM / m when the addition amount is 0.6%. It is thus inferred that the L-ascorbyl palmitate molecules are distributed on the surface layer in contact with air in the oil, which may affect the penetration process of oxygen into the oil.

[0071] After L-ascorbyl palmitate enters the walnut oil, its surfactant properties significantly change the surface tension of the system. The hydrophobic group (palmitic acid chain) of this molecule is preferentially adsorbed on the oil / gas interface under the action of hydrophobicity. As the concentration increases, the molecules are arranged in an orderly manner on the oil / gas interface to form a monolayer - the hydrophobic group extends into the oil phase and the hydrophilic group is exposed to the air.

[0072] The adsorption layer at the gas-liquid interface is formed by the directional adsorption of single-molecule lipophilic groups. When there is only one surfactant in the solution and adsorption equilibrium is reached at a certain temperature, the adsorption amount at the gas-liquid interface gives the relationship between the solution surface tension and the adsorption amount. The above shows that L-ascorbyl palmitate has an enrichment effect at the gas-liquid interface.

[0073] Comparative Example 1

[0074] Under the conditions of Example 3, Phase A was not prepared, and the addition amount of carnosic acid in Phase B was 0.015 g;

[0075] All other steps were the same as in Example 3.

[0076] The experimental results are shown in Table 4, Figure 2 as shown below.

[0077] As can be seen from Table 4, compared with the control, after adding the protective agent, the shelf life of walnut oil was extended to 3.75 years, that is, the oxidation stability of walnut oil was greatly increased.

[0078] Comparative Example 2

[0079] Under the conditions of Example 3, during the preparation of Phase A, α-tocopherol was not added, and only 0.24 g of L-ascorbyl palmitate was added;

[0080] All other steps were the same as in Example 3.

[0081] The experimental results are shown in Table 4, Figure 2 as shown below.

[0082] As can be seen from Table 4, compared with the control, after adding the protective agent, the shelf life of walnut oil was extended to 3.00 years, that is, the oxidation stability of walnut oil was greatly increased.

[0083] Comparative Example 3

[0084] Under the conditions of Example 3, during the preparation of Phase A, L-ascorbyl palmitate was not added, and only 0.24 g of α-tocopherol was added;

[0085] All other steps were the same as in Example 3.

[0086] The experimental results are shown in Table 4, Figure 2 as shown below.

[0087] As can be seen from Table 4, compared with the control, after adding the protective agent, the shelf life of walnut oil was extended to 1.75 years, that is, the oxidation stability of walnut oil was greatly increased.

[0088] Comparative Example 4

[0089] It should be "Under the conditions of Example 3, during the preparation of Phase A, Phase B was not prepared, and only 0.135 g of L-ascorbyl palmitate and 0.12 g of α-tocopherol were added".

[0090] The experimental results are shown in Table 4, Figure 2 as shown below.

[0091] As can be seen from Table 4, compared with the control, the shelf life of walnut oil is extended to 3.25 years after adding the protective agent, which greatly increases the oxidation stability of walnut oil.

[0092] The time required for the accelerated aging of pecan oil in different systems to exceed the national standard is shown in Table 4 below.

[0093] Table 4

[0094]

[0095] It can be seen from Table 4 that in Comparative Examples 2 and 3, the antioxidant effect of the oil system with only 0.24 g of α-tocopherol / AP added is weak; in Comparative Example 4, the synergistic AP + α-tocopherol system has a better antioxidant effect than the single systems of Comparative Examples 2 and 3, indicating that there is a synergistic effect between AP and α-tocopherol. In Comparative Example 1, the oil system with 0.24 g of carnosic acid has a good antioxidant effect itself, and is better than the AP + α-tocopherol system in Comparative Example 4, but weaker than the gallic acid + AP + α-tocopherol system in Example 4; while the system of carnosic acid + AP + α-tocopherol in Example 3 has a better antioxidant effect than that in Example 4, indicating that the system in Example 3 has the best effect of delaying oil oxidation.

[0096] It should be noted that the present invention is based on the oxidation competition mechanism of walnut kernel oil, and uses L-ascorbyl palmitate (AP), vitamin E (VE) and carnosic acid to prepare a natural antioxidant synergistic combination system through a suitable ratio. AP has both water-soluble and fat-soluble characteristics, adsorbs and disperses at the oil-water interface, and acts as an "interface antioxidant" to scavenge free radicals at the oil-water interface. Among the antioxidant molecular chaperones, VE is a fat-soluble antioxidant that protects polyunsaturated fatty acid chains and synergistically regenerates AP. Carnosic acid is a high-temperature resistant and powerful free radical scavenger (high temperature resistance > 200 °C), inhibits the oxidation of oil during high-temperature processing, and chelates metal ions (Fe2+ / Cu+), blocking the oxidation degradation pathways of AP and VE. The above three-component natural antioxidant system forms a regeneration cycle through a simple and feasible preparation process, and synergistically improves the oxidation stability and persistence of oil.

[0097] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A synergistic composition for protecting the oxidative stability of walnut kernel oil, characterized in that: include, Antioxidant molecular chaperone, antioxidant synergist and solvent; wherein the mass ratio of antioxidant molecular chaperone, antioxidant synergist and solvent is 0.20-0.80:0.01-0.05:2.60-3.50, the antioxidant molecular chaperone is composed of modified ascorbic acid ester and tocopherol, and the mass ratio of modified ascorbic acid ester: tocopherol is in the range of 5:5-7:3wt%.

2. The synergistic composition according to claim 1, characterized in that: The antioxidant synergist is one or more of ferulic acid, chlorogenic acid, carnosic acid and propyl gallate.

3. The synergistic composition according to claim 1 or 2, characterized in that: The solvent is 1,2-pentanediol or anhydrous ethanol.

4. Use of the synergistic composition described in any one of claims 1 to 3 in improving the oxidative stability of walnut oil.

5. The use according to claim 4, characterized in that: include, The antioxidant molecular chaperone is dissolved in the solvent by ultrasonication to obtain a uniform phase A; Adding antioxidant enhancer to walnut oil as phase B; The A and B phases are mixed evenly and dissolved by ultrasound to obtain a natural and long-lasting molecular composition for protecting the oxidative stability of walnut oil.

6. The use according to claim 5, characterized in that: The walnut oil variety is one or more of bubble walnut oil, iron walnut oil, high-yield pecan oil, large bubble walnut oil, and water-substituted walnut oil.

7. The use according to claim 5, characterized in that: Calculated by the mass percentage of raw materials, the content of the antioxidant molecular chaperone is 0.20-0.80%, the content of the antioxidant synergist is 0.01-0.05%, the content of the solvent is 2.60-3.50%, and the content of the walnut oil is 98.00-100.00%.

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