Low-temperature plasma pretreatment technology

Abstract

The invention relates to the technical field of sesame processing, in particular to a low-temperature plasma pretreatment technology, and solves the problems of high extraction cost, serious pollution and the like of traditional protein extraction methods such as an alkali-solution and acid-isolation method, an enzymolysis method, a membrane filtration method and the like in the prior art, unsatisfactory protein content of extracted protein, low extraction cost and the like. Generation of bitter peptides is often caused in the extraction process, meanwhile, functional characteristics such as solubility, foaming performance and emulsifying performance of the protein are lost, and application of the sesame protein in the food industry is seriously restricted. The low-temperature plasma pretreatment technology comprises the following steps: removing residual grease in sesame residues, screening out sesame powder, stirring for three times to remove the residual grease, carrying out low-temperature plasma pretreatment, and mixing the degreased sesame powder with deionized water. Compared with a traditional alkali-solution and acid-isolation method, low-temperature plasma pretreatment is easy and convenient to operate and environmentally friendly, and the obvious advantage is shown in the aspect of improving the protein extraction rate.

Description

Technical Field

[0001] The invention relates to the technical field of sesame processing, in particular to a low-temperature plasma pretreatment technology. Background Art

[0002] As an emerging physical treatment technology, low-temperature plasma pretreatment technology has shown its unique advantages and application potential in many fields. It uses the active particles generated by low-temperature plasma to interact with the surface of the material, thereby changing the surface properties and structure of the material, creating favorable conditions for subsequent processing.

[0003] In the sesame processing industry, sesame is one of the world's major oil crops, and about 70% of sesame is used for oil extraction. The annual output of sesame residue, a byproduct of oil extraction, can reach one million tons. Its protein content is as high as 45%-55%, and its amino acid composition is balanced, which has the potential to become a source of high-quality plant protein. However, sesame residue is currently used as low-value feed or discarded, resulting in a serious waste of a large amount of high-quality protein resources. Recovering and extracting sesame protein from sesame residue is one of the ways to achieve its high-value utilization, which is of great significance to promoting the sustainable development of the sesame industry.

[0004] However, in the specific protein extraction process, the existing traditional protein extraction methods, such as alkali dissolution and acid precipitation, enzymatic hydrolysis, membrane filtration, etc., have gradually exposed a series of obvious limitations and technical problems. Specifically, these methods not only have problems such as high extraction cost and serious pollution, but also the protein content of the extracted protein is not ideal. Traditional methods often lead to the production of bitter peptides during the extraction process, and the functional properties of the protein, such as solubility, foaming properties and emulsification properties, will also be lost, which seriously restricts the application of sesame protein in the food industry. Therefore, in view of the many shortcomings in the existing technology, we urgently need an innovative physical pretreatment technology to solve these problems. Summary of the invention

[0005] The purpose of the present invention is to provide a low-temperature plasma pretreatment technology, which solves the problems that traditional protein extraction methods in the prior art, such as alkali dissolution and acid precipitation method, enzymatic hydrolysis method, membrane filtration method, etc., not only have high extraction cost and serious pollution, but also the protein content of the extracted protein is not ideal, and bitter peptides are often generated during the extraction process. At the same time, the functional properties of the protein, such as solubility, foaming performance and emulsification performance, will also be lost, which seriously restricts the application of sesame protein in the food industry.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] Low-temperature plasma pretreatment technology includes the following steps:

[0008] Step 1: Remove the residual oil in the sesame residue, sift out the sesame powder, and stir three times to remove the residual oil;

[0009] Step 2: low-temperature plasma pretreatment, defatted sesame powder is mixed with deionized water;

[0010] Step 3: Extract protein from sesame residue by centrifugation, retain the supernatant, and then freeze-dry to obtain sesame protein.

[0011] Preferably, to remove the residual oil in the sesame residue, the sesame cake is finely ground to ensure that its particle size is uniform, which is convenient for subsequent oil removal operations. The ground sesame powder needs to be sieved through a 60-mesh sieve to remove larger particles and impurities to obtain fine sesame powder. Subsequently, in order to effectively remove the residual oil in the sesame powder, we use n-hexane as an extractant, mix the sesame powder and n-hexane in a ratio of 1:5, and fully stir at room temperature. The stirring time is set to 2 hours to ensure that the oil can be fully extracted. In order to improve the oil removal effect, this extraction process is carried out 3 times, each time using fresh n-hexane, and ensuring that the stirring conditions are consistent. Through this step, the oil content in the sesame powder can be effectively reduced, creating favorable conditions for subsequent low-temperature plasma pretreatment and protein extraction.

[0012] Preferably, after low-temperature plasma pretreatment and oil removal treatment, the sesame powder needs to be mixed with deionized water to prepare a suspension suitable for low-temperature plasma treatment. The mixing ratio and specific concentration can be adjusted according to experimental requirements. Subsequently, the suspension is treated using a CTP-2000K dielectric barrier discharge low-temperature plasma device. During the treatment process, the current is set to 2A, and different voltages of 25, 35, and 45V are selected for experiments to explore the effect of voltage on the low-temperature plasma treatment effect. The treatment time is set to 2 minutes to ensure that the treatment process is both sufficient and efficient. Low-temperature plasma treatment can change the physical and chemical properties of the surface of sesame powder, which is helpful for the subsequent protein extraction process.

[0013] Preferably, for the extraction of protein from sesame residue, the suspension after low-temperature plasma pretreatment needs to be subjected to a protein extraction operation. First, the pH value of the suspension is adjusted to 11. This alkaline condition helps to destroy the interaction between sesame protein and other components, making the protein easier to extract. Under the condition of a pH value of 11, the suspension is fully stirred, and the stirring time is set to 2 hours to ensure that the protein can be fully dissolved in the suspension. Subsequently, the solid particles and the liquid part in the suspension are separated by centrifugation, and the supernatant is retained as a protein extract. Next, the pH value of the supernatant is adjusted to 4. This acidic condition can cause the protein to precipitate. Centrifugation is performed again to obtain a protein precipitate. Finally, the collected protein precipitate is redissolved to restore its pH value to 7 to maintain the stability and activity of the protein. The redissolved protein solution is freeze-dried to obtain a pure sesame protein product.

[0014] Preferably, the protein is dissolved, the pH value of the suspension is adjusted to 11, the interaction between sesame protein and other ingredients is destroyed, sufficient stirring is performed under the condition of a pH value of 11, the stirring speed and time are controlled to ensure that the protein is fully dissolved, and the stirring time is set to 2 hours to ensure sufficient dissolution of the protein and avoid protein denaturation or degradation.

[0015] Preferably, protein precipitation is performed by separating the solid particles and the liquid portion in the suspension by centrifugation, retaining the supernatant as a protein extract, adjusting the pH value of the supernatant to 4 to precipitate the protein, and slowly adjusting the pH value to observe the formation of the precipitate, and performing centrifugation again to obtain a protein precipitate.

[0016] The present invention has at least the following beneficial effects:

[0017] As an innovative physical treatment method, low-temperature plasma pretreatment technology has a significant effect on the surface structure and properties of sesame residue. Compared with the traditional alkali dissolution and acid precipitation method, low-temperature plasma pretreatment is not only easy to operate and environmentally friendly, but also shows significant advantages in improving the protein extraction rate. Specifically, after low-temperature plasma pretreatment, the protein extraction rate in sesame residue increased by 39.36%, which is a considerable increase and provides strong support for the efficient utilization of sesame protein. At the same time, the protein content in the extracted protein can reach 90%, which further ensures the purity and quality of sesame protein. More importantly, low-temperature plasma pretreatment can also regulate the functional properties of protein in a directional manner, which is difficult to match with the traditional alkali dissolution and acid precipitation method. Under a treatment voltage of 25V, the oil holding capacity of sesame residue protein has been significantly improved to 13.34. The improvement in oil holding capacity means that sesame protein can better stabilize oil in food processing and improve the taste and quality of the product. Under a treatment voltage of 35V, the solubility of sesame residue protein increased by 14%, which makes the protein easier to disperse in the solution, which is conducive to subsequent processing and application. In addition, the foaming property has also been improved by 16%, which means that sesame protein can produce more delicate and stable foam when making foam foods. At the same time, the emulsification stability has also been significantly improved to 484 minutes, which allows sesame protein to remain stable in the emulsification system for a longer time, providing a strong guarantee for the development of emulsified foods. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] Embodiment 1

[0020] It includes the following steps:

[0021] Step 1: Remove the residual oil in the sesame residue, sift out the sesame powder, and stir three times to remove the residual oil;

[0022] Step 2: low-temperature plasma pretreatment, defatted sesame powder is mixed with deionized water;

[0023] Step 3: Extract protein from sesame residue by centrifugation, retain the supernatant, and then freeze-dry to obtain sesame protein.

[0024] After low-temperature plasma pretreatment, the protein extraction rate in sesame residue increased by 39.36%, which is a considerable increase and provides strong support for the efficient use of sesame protein. At the same time, the protein content of the extracted protein can reach 90%, which further ensures the purity and quality of sesame protein.

[0025] Embodiment 2

[0026] To remove the residual oil in the sesame residue, the sesame cake is finely ground to ensure that its particle size is uniform, which is convenient for the subsequent oil removal operation. The ground sesame powder needs to be sieved through a 60-mesh sieve to remove larger particles and impurities to obtain fine sesame powder. Then, in order to effectively remove the residual oil in the sesame powder, we use n-hexane as the extraction agent, mix the sesame powder and n-hexane in a ratio of 1:5, and fully stir at room temperature. The stirring time is set to 2 hours to ensure that the oil can be fully extracted. In order to improve the oil removal effect, this extraction process is carried out 3 times, and fresh n-hexane is used each time, and the stirring conditions are ensured to be consistent. Through this step, the oil content in the sesame powder can be effectively reduced, creating favorable conditions for subsequent low-temperature plasma pretreatment and protein extraction.

[0027] The sesame cakes are finely ground to ensure uniform particle size, and then sieved through a 60-mesh sieve to remove larger particles and impurities to obtain fine sesame powder, which is convenient for subsequent oil removal operations.

[0028] Embodiment 3

[0029] Low-temperature plasma pretreatment, the sesame powder after oil removal treatment needs to be mixed with deionized water to prepare a suspension suitable for low-temperature plasma treatment. The mixing ratio and specific concentration can be adjusted according to experimental requirements. Subsequently, the suspension is treated using the CTP-2000K dielectric barrier discharge low-temperature plasma equipment. During the treatment process, the current is set to 2A, and different voltages of 25, 35, and 45V are selected for experiments to explore the effect of voltage on the low-temperature plasma treatment effect. The treatment time is set to 2 minutes to ensure that the treatment process is both sufficient and efficient. Low-temperature plasma treatment can change the physical and chemical properties of the surface of sesame powder, which is helpful for the subsequent protein extraction process.

[0030] Defatted sesame powder was mixed with deionized water to form a suspension, which was treated with a plasma device at 2A current and 25 / 35 / 45V voltage for 2 minutes to change the physical and chemical properties of the sesame powder surface, which was helpful for the subsequent protein extraction process.

[0031] Embodiment 4

[0032] The extraction of protein from sesame residue, after the suspension is pretreated by low-temperature plasma, needs to be subjected to protein extraction operation. First, the pH value of the suspension is adjusted to 11. This alkaline condition helps to destroy the interaction between sesame protein and other components, making the protein easier to extract. Under the condition of pH 11, the suspension is fully stirred, and the stirring time is set to 2 hours to ensure that the protein can be fully dissolved in the suspension. Subsequently, the solid particles and liquid parts in the suspension are separated by centrifugation, and the supernatant is retained as the protein extract. Next, the pH value of the supernatant is adjusted to 4. This acidic condition can cause the protein to precipitate. Centrifugation is performed again to obtain protein precipitate. Finally, the collected protein precipitate is redissolved to restore its pH value to 7 to maintain the stability and activity of the protein. The redissolved protein solution is freeze-dried to obtain a pure sesame protein product.

[0033] The pH of the suspension was adjusted to 11 and stirred for 2 hours to destroy the interaction between sesame protein and other ingredients, making the protein easier to extract. The supernatant was retained by centrifugation, and the pH of the supernatant was adjusted to 4. The protein was centrifuged again to obtain a protein precipitate, which effectively separated and precipitated the protein, providing a basis for subsequent re-dissolution and freeze-drying. The protein precipitate was re-dissolved to a pH of 7, and then freeze-dried to obtain a pure sesame protein product, maintaining the stability and activity of the protein.

[0034] Embodiment 5

[0035] Dissolve the protein. Adjust the pH value of the suspension to 11 to destroy the interaction between sesame protein and other ingredients. Stir fully at a pH of 11. Control the stirring speed and time to ensure that the protein is fully dissolved. Set the stirring time to 2 hours to ensure that the protein is fully dissolved and avoid protein denaturation or degradation.

[0036] Adjust the pH value of the suspension to 11, control the stirring speed and time to fully stir, ensure that the protein is fully dissolved, and avoid protein denaturation or degradation.

[0037] Embodiment 6

[0038] Protein precipitation, separate the solid particles and liquid part in the suspension by centrifugation, retain the supernatant as the protein extract, adjust the pH value of the supernatant to 4 to precipitate the protein, and slowly adjust the pH value to observe the precipitation formation, and centrifuge again to obtain protein precipitation.

[0039] The solid particles and the liquid part are separated by centrifugation, and the supernatant is retained; the pH value of the supernatant is adjusted to 4 to precipitate the protein, and the pH value is slowly adjusted to observe the precipitation formation, so as to effectively obtain the protein precipitate and provide high-quality raw materials for subsequent re-dissolution and freeze-drying processing.

[0040] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. Low-temperature plasma pretreatment technology includes the following steps: Step 1: Remove the residual oil in the sesame residue, sift out the sesame powder, and stir three times to remove the residual oil; Step 2: low-temperature plasma pretreatment, defatted sesame powder is mixed with deionized water; Step 3: Extract protein from sesame residue by centrifugation, retain the supernatant, and then freeze-dry to obtain sesame protein.

2. The low-temperature plasma pretreatment technology according to claim 1, characterized in that: To remove the residual oil in the sesame residue, the sesame cake is finely ground to ensure that its particle size is uniform, which is convenient for the subsequent oil removal operation. The ground sesame powder needs to be sieved through a 60-mesh sieve to remove larger particles and impurities to obtain fine sesame powder. Subsequently, in order to effectively remove the residual oil in the sesame powder, we use n-hexane as an extractant, mix the sesame powder and n-hexane in a ratio of 1:5, and fully stir at room temperature. The stirring time is set to 2 hours to ensure that the oil can be fully extracted. In order to improve the oil removal effect, this extraction process is carried out 3 times, each time using fresh n-hexane, and ensuring that the stirring conditions are consistent. Through this step, the oil content in the sesame powder can be effectively reduced, creating favorable conditions for subsequent low-temperature plasma pretreatment and protein extraction.

3. The low-temperature plasma pretreatment technology according to claim 1, characterized in that: The sesame powder after the low-temperature plasma pretreatment and oil removal treatment needs to be mixed with deionized water to prepare a suspension suitable for low-temperature plasma treatment. The mixing ratio and specific concentration can be adjusted according to experimental requirements. Subsequently, the suspension is treated using a CTP-2000K dielectric barrier discharge low-temperature plasma device. During the treatment process, the current is set to 2A, and different voltages of 25, 35, and 45V are selected for experiments to explore the influence of voltage on the low-temperature plasma treatment effect. The treatment time is set to 2 minutes to ensure that the treatment process is both sufficient and efficient. The low-temperature plasma treatment can change the physical and chemical properties of the surface of the sesame powder, which is helpful for the subsequent protein extraction process.

4. The low-temperature plasma pretreatment technology according to claim 1, characterized in that: The protein extraction from the sesame residue is performed on the suspension after low-temperature plasma pretreatment. The protein extraction operation is performed next. First, the pH value of the suspension is adjusted to 11. This alkaline condition helps to destroy the interaction between sesame protein and other components, making the protein easier to extract. Under the condition of a pH value of 11, the suspension is fully stirred, and the stirring time is set to 2 hours to ensure that the protein can be fully dissolved in the suspension. Subsequently, the solid particles and the liquid part in the suspension are separated by centrifugation, and the supernatant is retained as a protein extract. Next, the pH value of the supernatant is adjusted to 4. This acidic condition can cause the protein to precipitate. Centrifugation is performed again to obtain a protein precipitate. Finally, the collected protein precipitate is redissolved to restore its pH value to 7 to maintain the stability and activity of the protein. The redissolved protein solution is freeze-dried to obtain a pure sesame protein product.

5. The low-temperature plasma pretreatment technology according to claim 4, characterized in that: The protein is dissolved, and the pH value of the suspension is adjusted to 11 to destroy the interaction between sesame protein and other ingredients. The suspension is fully stirred at a pH of 11, and the stirring speed and time are controlled to ensure that the protein is fully dissolved. The stirring time is set to 2 hours to ensure that the protein is fully dissolved and avoid protein denaturation or degradation.

6. The low-temperature plasma pretreatment technology according to claim 4, characterized in that: The protein precipitation is carried out by separating the solid particles and the liquid part in the suspension by centrifugation, retaining the supernatant as a protein extract, adjusting the pH value of the supernatant to 4 to precipitate the protein, and slowly adjusting the pH value to observe the precipitation formation, and centrifuging again to obtain a protein precipitate.