Sunflower seed protein-chitosan hydrochloride compound as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of food processing, and particularly relates to a sunflower seed protein-chitosan hydrochloride compound as well as a preparation method and application thereof. According to the preparation method, a sunflower seed protein (SSP)-chitosan hydrochloride (CHC) compound (SSP-CHC) is prepared, stir-fried sunflower seed kernels are obtained through intermediate infrared stir-frying, the stir-fried sunflower seed kernels are ground to obtain sunflower seed paste, and the sunflower seed paste and the SSP-CHC are mixed and thermally homogenized to prepare the sunflower seed sauce. In the preparation process of the sunflower seed sauce, a compound formed by protein and polysaccharide has the functional characteristics of good emulsification, coagulation, interface adsorption and the like of the protein and also has the processing characteristics of excellent water-holding capacity, thickening property and the like of the polysaccharide, directional design of sunflower seed protein and chitosan is developed, and thermal homogenization and thermal canning are adopted, so that the sunflower seed sauce is prepared. The sunflower seed sauce is rich in fragrance and stable to store. The heat effect of degrading chlorogenic acid and increasing the content of flavor substances by mid-infrared rays and the favorable barrier effect of the spatial network structure of the protein-polysaccharide compound are combined, so that the problems that the sunflower seed sauce is easy to separate oil, oxidize and discolor are effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and specifically, the invention relates to a sunflower seed protein-chitosan hydrochloride complex and a preparation method and application thereof. Background Art

[0002] Sunflower seeds are a nutritious, high-quality oil nut. 90% of the oil they contain is unsaturated fatty acids, of which linoleic acid content is as high as about 70%, higher than sesame and peanuts. Appropriate supplementation of sunflower seeds can reduce cholesterol levels and the incidence of cardiovascular diseases. Sunflower seeds are divided into oil sunflowers for oil extraction and edible sunflowers for direct consumption. The oil content of oil sunflowers is as high as 60%, and the oil content of edible sunflowers is 40-50%. Sunflower seeds also contain 20-25% protein, vitamin E, lecithin, and trace elements such as calcium, magnesium, and iron. In addition to being directly fried into snack foods such as sunflower seeds and sunflower kernels, edible sunflowers are also processed into sunflower seed powder, sunflower seed crumbs, etc. as ingredients for baked goods, candies, etc., and even processed into sunflower seed sauce.

[0003] Sunflower seed butter is made of shelled sunflower kernels as the main raw material, with sugar and salt as auxiliary materials. It is an oil-in-water colloid product made through frying, grinding, canning and other processes. Sunflower seed butter does not contain allergens, is low in calories, and is high in calcium, iron, vitamin E and B vitamins. According to measurements, the iron and vitamin E content of sunflower seed butter is 3-4 times higher than that of peanut butter. However, compared with sesame butter, sunflower seed butter is less stable and is more prone to quality deterioration such as oil separation, rancidity and darkening during storage.

[0004] Stir-frying is a key step that affects the flavor and stability of sunflower seed butter, sesame butter, peanut butter and other sauce products. In addition to stir-frying in a casserole, there are also electric stir-frying, microwave stir-frying, infrared heating stir-frying and so on. The control of stir-frying method, stir-frying temperature, stir-frying time and kernel moisture content plays a decisive role in the flavor and quality of the sauce products. While stir-frying reduces the moisture content of the kernels and enhances the flavor of the sauce products, it also destroys the cell structure of the nut kernels, causing the oil to lose the protection of the oil body membrane protein and be easily oxidized, resulting in poor antioxidant stability of the sauce products. In order to improve the antioxidant properties of the sauce products, it is often necessary to add natural antioxidants or synthetic antioxidants. The advantage of synthetic antioxidants is that they are effective, but they are very likely to bring potential food safety risks. Although natural antioxidants are not very effective, they are healthier and safer, meeting the needs of consumers. Mid-infrared (MIR) radiation heating technology causes the material's internal molecules to vibrate and generate heat through friction after the infrared rays are absorbed by the material, which increases the material's internal temperature, thereby achieving rapid dehydration. It is also used for food processing such as blanching, peeling, sterilization, enzyme inactivation, baking, polyphenol recovery, and starch modification. A large number of studies have shown that infrared treatment can increase the polyphenol content and antioxidant capacity of nuts such as pecans. However, due to the different absorption of infrared rays by various components in food materials, the heating degree of different food materials at the same infrared wavelength is inconsistent.

[0005] Grinding is an important factor affecting the flavor and stability of sesame, peanut and other paste products. Grinding is an important measure to obtain the appropriate particle size through grinding tools such as stone mills, colloid mills, food processors, and medium mills. If the particle size is too small, the colloid stability of the paste will deteriorate, and if the particle size is too large, it is easy to sink and cause the paste to be stratified. The system stability of sunflower seed paste, sesame paste and other paste products is also closely related to the compatibility of various components in the paste, such as protein, crude fiber, and carbohydrates. In order to prevent the oil from floating up during the storage of the sauce product and keep the sauce product uniform and stable, it is often necessary to add stabilizers such as β-sitosterol and monoglyceride.

[0006] Sunflower seeds (meal) contain a large amount of polyphenol compounds, among which the high content of chlorogenic acid easily interacts with protein to make the protein green. Protein greening not only reduces the digestibility of protein, but also has a negative impact on the sensory and flavor of sunflower seed protein and sunflower seed butter. Therefore, before the extraction and processing of sunflower seed protein, the following measures are needed to remove chlorogenic acid: ① Based on the solubility of chlorogenic acid, it is removed by extraction with organic solvents such as methanol; ② Based on the oxidative properties of chlorogenic acid, it is removed by reducing agents or inhibitors; ③ Through biological enzymes or physical fields such as ultrasound and microwaves to assist in organic solvent extraction and removal.

[0007] In the prior art, the patent with publication number CN 108576745A discloses a flavor-enhanced sunflower seed paste and its preparation method, the patent with publication number CN 112931846 A discloses a processing method of selenium-enriched sunflower seed kernel paste, the patent with publication number CN 117796513A discloses a Torreya grandis sunflower seed paste and its preparation method, the patent with publication number CN104413487 A discloses a sunflower seed paste production process for controlling aflatoxin, the patent with publication number CN107343641A discloses a method for making sunflower seed paste, and the patent with publication number CN103519141A discloses a sunflower seed mutton paste. On the one hand, these patents do not disclose how to solve the problems of sunflower seed paste being easy to oil, oxidize, and change color; on the other hand, these patents have complicated processing processes, use external additives, and have the risk of being contaminated and affecting food safety. Summary of the invention

[0008] In order to solve the problems of existing sunflower seed paste, such as easy oil separation, easy oxidation and easy discoloration during storage, the present invention develops a method for extracting sunflower seed protein, directionally designs a sunflower seed protein-chitosan hydrochloride complex, and prepares sunflower seed paste with added sunflower seed protein-chitosan hydrochloride complex. The obtained sunflower seed paste has high antioxidant activity and strong stability and meets the clean label standard of food production.

[0009] The present invention is achieved according to the following technical solutions: In one aspect of the present invention, the present invention discloses a method for preparing a sunflower seed protein-chitosan hydrochloride complex, the method comprising: S1. Preparation of sunflower seed protein (SSP) stock solution: SSP was slowly added into deionized water at a mass volume ratio of (0.45-0.50):100, followed by stirring at room temperature of 20-25°C and 150-200 rpm for 2-2.5 hours, and then subjected to ultrasonic treatment at a power of 100-125 kHz for 20-25 minutes to obtain an SSP stock solution; S2. Preparation of chitosan hydrochloride (CHC) stock solution: CHC is slowly added into deionized water at a mass volume ratio of (0.45-0.50):100, followed by stirring at room temperature (20-25°C) and 150-200 rpm for 2-2.5 hours, and then subjected to ultrasonic treatment at a power of 100-125 kHz for 20-25 minutes to obtain a CHC stock solution; S3. Preparation of SSP-CHC: First, the CHC stock solution was slowly added to the SSP stock solution in a mass ratio of SSP stock solution to CHC stock solution of (3 ~ 4):1, and stirred overnight at room temperature of 20 ~ 25 ℃ and 100 ~ 200 rpm; then, it was placed in a 4 ~ 8 ℃ environment for cold treatment for 20 ~ 24 hours; then, the pH value of the mixed solution was adjusted to 4.0 ~ 4.5 with 0.1 M HCl; after incubation at 75 ~ 80 ℃ for 7.5 ~ 8.0 hours, it was placed in an ice water bath for cooling for 0.5 ~ 1.0 hour, and then placed in a dialysis bag with a molecular weight cutoff of 25 kDa and dialyzed in running tap water at room temperature for 24 hours. Finally, it was freeze-dried to constant weight to obtain an SSP-CHC complex.

[0010] The basic characteristic parameters of the SSP-CHC are as follows: SSP-CHC is a cream-yellow powder, with a grafting degree of 57.0 ± 2.0%, a particle size of 360 ± 10 nm, a Zeta potential of 43 ± 2.5 mv, a PDI (Polymer Dispersity Index) of 0.40 ± 0.05, a fluorescence intensity of 115.0 ± 13.0, a surface hydrophobicity of 140.0 ± 10.0, a denaturation temperature of 153.0 ± 5.0 °C, an enthalpy of 18.0 ± 2.0 J / g, and the contents of α-helix, β-fold, β-turn and random coil in the secondary structure are 12.0 ± 0.5%, 32.5 ± 1.2%, 43.5 ± 2.1% and 11.5 ± 0.6%, respectively.

[0011] In one embodiment of the present invention, the sunflower seed protein of the present invention is prepared by the following method, which comprises: (1) Mid-infrared frying of sunflower seed kernels The moisture content of the sunflower seed kernels is adjusted to 10-12%, and the kernels are placed in a mid-infrared frying barrel, and fry for 4-5 minutes at an infrared power of 700-800W, so that the surface temperature of the kernels reaches 180-200°C, and the kernels are immediately placed in a vibrating screen for shaking and air separation to remove the inner seed coat of the sunflower seeds, thereby obtaining fried sunflower seed kernels; (2) Preparation of sunflower seed protein (SSP) The roasted sunflower kernels were crushed and defatted with n-hexane-methanol (v:v=9:1), filtered, and the retentate was collected. The retentate was placed in a ventilated place overnight to obtain sunflower seed powder; the sunflower seed powder was dispersed in a NaCl aqueous solution with a solid-liquid ratio of 1: (18 ~ 20), and ultrasonic-assisted extraction was performed at 40 ± 1 ℃ for 3.0 hours to obtain an extract; the extract was centrifuged at 10000 r / min for 20 minutes, and the supernatant was collected; ammonium sulfate powder was slowly added to the supernatant to make the ammonium sulfate saturation reach 65 ~ 75%, and the supernatant was allowed to stand at room temperature for 30 minutes, and then centrifuged at 100000 r / min for 20 minutes to collect precipitate A; the precipitate A was dispersed in a 0.01M, pH4.5 ± 0.1 phosphate buffer at a mass volume ratio of 1:10, and placed in an environment of 4 ~ 8 ℃ for 24 hours, and then centrifuged at 100000 r / min for 20 minutes. min, collect the precipitate B; desalt the precipitate B by ultrafiltration and then dry it in vacuum to constant weight to obtain SSP.

[0012] In one aspect of the present invention, the present invention discloses the use of the sunflower seed protein-chitosan hydrochloride complex prepared by the method of the present invention in the preparation of sunflower seed paste.

[0013] In one embodiment, the present invention discloses a method for preparing sunflower seed butter, the method comprising: (1) Put the roasted sunflower seed kernels into a multifunctional grinder or a stone mill and grind them for 15 to 20 minutes to obtain a sunflower seed paste with a particle size of 60 to 65 μm; (2) Add 1 to 3% (mass percentage) of sunflower seed protein-chitosan hydrochloride complex (SSP-CHC) to the sunflower seed paste, then homogenize and stir at 75 to 80° C. for 25 to 30 minutes, and hot-can the mixture to obtain sunflower seed paste.

[0014] The basic properties of the sunflower seed butter are as follows: the sunflower seed butter is orange (salmonorange in the RAL international standard color card), the average volume particle size of the butter (D 4,3 ) and area average particle size (D 3,2 ) are 30 ~ 45 μm and 8 ~ 12 μm respectively. The texture characteristic parameters of hardness, consistency, cohesion and viscosity are 300 ~ 600 g, 2000 ~ 4000 g / sec, -800 ~ -1700g and -600 ~ -1400 g.sec respectively. The centrifugal oil separation rate is 6.5 ~ 8.5%. The acid value and peroxide value are 0.90 ~1.10 and 0.85 ~ 0.92 respectively. The shelf life at room temperature is 90 ~ 120 days. Beneficial Effects

[0015] Compared with the prior art, the advantages and positive effects of the present invention are: ① The present invention utilizes the process of mid-infrared frying of sunflower seeds to achieve a degradation rate of chlorogenic acid in sunflower seed kernels of 25.0% to 30.0%, thereby increasing the abundance of volatile flavor components of sunflower seed paste by 100-130%; meanwhile, the greening problem of sunflower seed protein and sunflower seed paste is suppressed.

[0016] ② The present invention combines the colloidal stabilizer function of the sunflower seed protein-chitosan hydrochloride complex to reduce the particle size of the sunflower seed paste by 17% to 35%, increase the colloidal viscosity, and effectively inhibit the oil separation problem of the sunflower seed paste; ③ The sunflower seed protein-chitosan hydrochloride complex combined with mid-infrared frying process colloid extended the storage period of sunflower seed paste by 10 to 30 days; ④ The mid-infrared hot frying, n-hexane-methanol degreasing, and ultrasound-assisted neutral salt solution extraction processes of sunflower seed protein disclosed in the present invention effectively solve the discoloration problem caused by the interaction between chlorogenic acid and protein in the sunflower seed protein processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 , diagram of the sunflower seed mid-infrared frying equipment, including a bracket, a ceramic infrared heater, a roller, a power controller, and a transmission; Figure 2 , SSP and SSP-CHC powders prepared in Example 1, the sunflower seed protein powder (SSP) is light yellow with a rough surface; while the sunflower seed protein-chitosan hydrochloride conjugate (SSP-CHC) is white and loose and porous.

[0018] Figure 3 , Molecular characteristic diagram of SSP-CHC prepared in Example 1 (A, particle size distribution diagram; B, endogenous fluorescence spectrum diagram; C, infrared spectrum diagram; D, differential scanning calorimetry analysis diagram; E, scanning electron microscope diagram) Figure 4 , Characteristic diagrams of the sunflower seed butter prepared in Examples 2-4 (A, macroscopic diagram; B, microscopic diagram; C, particle size distribution diagram; D, shear stress-shear frequency flow curve; E, apparent viscosity-shear frequency curve; F, storage modulus / loss modulus-frequency scanning diagram) DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with specific embodiments. The features and advantages of the present invention will become clearer as the description proceeds, but these exemplary embodiments are only used to illustrate the present invention and do not constitute any limitation on the scope of the present invention.

[0020] The sunflower kernels used in the embodiments of the present invention were purchased from Junyuan Planting Industry Professional Cooperative in Changchun City, Baicheng District, Jilin Province, and the chitosan hydrochloride (with a deacetylation degree of 80.0%-90.0%) was purchased from Shanghai MacLean Biochemical Technology Co., Ltd. Example 1

[0021] 1.1 Preparation of sunflower seed protein, the preparation method comprising: Step 1: Mid-infrared roasting of sunflower seed kernels Adjust the moisture content of sunflower seed kernels to 10% and place them in a mid-infrared roasting barrel (attached Figure 1 ), frying at an infrared power of 700 for 5 minutes until the surface temperature of the sunflower seed kernels reaches 182 ± 1 °C, and immediately placing them in a vibrating screen for shaking and air separation to remove the inner seed coat of the sunflower seeds, thereby obtaining fried sunflower seed kernels; Step 2: Preparation and processing of SSP The roasted sunflower kernels were crushed and defatted with n-hexane-methanol (v:v=9:1), filtered, and the retentate was collected. The retentate was placed in a ventilated place overnight to obtain sunflower seed powder; the sunflower seed powder was dispersed in a NaCl aqueous solution with a solid-liquid ratio of 1:18, and ultrasonic-assisted extraction was performed at 40 ± 1 ℃ for 3.0 hours to obtain an extract; the extract was centrifuged at 10000 r / min for 20 minutes, and the supernatant was collected; ammonium sulfate powder was slowly added to the supernatant to make the ammonium sulfate saturation reach 65-75%, and the supernatant was allowed to stand at room temperature for 30 minutes, and then centrifuged at 100000 r / min for 20 minutes to collect precipitate A; the precipitate A was dispersed in a 0.01M phosphate buffer with a mass volume ratio of 1:10, and placed in an environment of 4-8 ℃ for 24 hours, and then centrifuged at 100000 r / min for 20 minutes. min, collect the precipitate B; after ultrafiltration and desalination, precipitate B is vacuum dried to constant weight to obtain SSP (attached Figure 2 (A), yield: 2.12±0.08%.

[0022] 1.2 The preparation steps of sunflower seed protein-chitosan hydrochloride complex (SSP-CHC) are as follows (1) Preparation of sunflower seed protein (SSP) stock solution The prepared SSP was slowly added into deionized water at a mass volume ratio of SSP to deionized water of 0.45:100, followed by stirring at room temperature and 200 rpm for 2 hours, and then subjected to ultrasonic treatment at a power of 100 kHz for 25 minutes to obtain an SSP stock solution; (2) Preparation of chitosan hydrochloride (CHC) stock solution CHC was slowly added into deionized water at a mass volume ratio of CHC to deionized water of 0.45:100, followed by stirring at room temperature and 200 rpm for 2 hours, and then subjected to ultrasonic treatment at a power of 100 kHz for 25 minutes to obtain a CHC stock solution; (3) Preparation of SSP-CHC First, the CHC stock solution was slowly added to the SSP stock solution at a mass ratio of 4:1 between the SSP stock solution and the CHC stock solution, and stirred overnight at room temperature and 200 rpm; then, the mixture was placed in a 4°C refrigerator for 24 hours; then, the pH value of the mixed solution was adjusted to 4.5 with 0.1 M HCl; after incubation at 80°C for 7.5 hours, the mixture was placed in an ice water bath for 1.0 hour, and then dialyzed in running tap water at room temperature for 24 hours in a dialysis bag with a molecular weight cutoff of 25 kDa. Finally, the mixture was freeze-dried to constant weight to obtain the SSP-CHC complex (attached Figure 2 Middle B); The grafting degree of SSP-CHC was 57.0 ± 2.0%, the Zeta potential was 43 ± 2.5 mv, the PDI was 0.40 ± 0.05, the surface hydrophobicity was 140.0 ± 10.0, the denaturation temperature was 153.0 ± 5.0 ℃, the enthalpy was 18.0 ± 2.0 J / g, and the contents of α-helix, β-sheet, β-turn and random coil in the secondary structure were 12.0 ± 0.5%, 32.5 ± 1.2%, 43.5 ± 2.1% and 11.5 ± 0.6%, respectively; the particle size distribution, intrinsic fluorescence spectrum, infrared spectrum, differential scanning calorimetry analysis and scanning electron microscopy can be found in the attached figure. Figure 3 .

[0023] Specific: The particle size distribution of SSP-CHC is shown in Figure 3 As shown in Figure A, both SSP and SSP-CHC have a bimodal distribution, but the main peak of SSP-CHC shifts to the left and the particle size becomes smaller; the particle sizes of SSP and SSP-CHC are 1300 ± 105 nm and 660 ± 32 nm, respectively. This is because the groups on CHC increase the repulsion between SSP molecules and inhibit their aggregation, thereby reducing the particle size of the SSP-CHC complex.

[0024] The endogenous fluorescence spectrum of SSP-CHC is shown in Figure 3 As shown in Figure B, the maximum emission wavelengths of SSP and SSP-CHC are approximately 340 nm and 350 nm, respectively. Compared with SSP, the fluorescence intensity of SSP-CHC is weakened and the emission wavelength is shifted to the right, which is because the grafting of CHC shields the aromatic amino acid residues such as tryptophan Trp, tyrosine Tyr and phenylalanine Phe in SSP.

[0025] The infrared spectrum of SSP-CHC is shown in Figure 3 As shown in C, when SSP is coupled with CHC molecules, the number of hydroxyl groups increases significantly, 3200-3600 cm -1The absorption band at -OH caused by the stretching vibration is more intense than that of SSP, indicating that a covalent bond is formed between SSP and CHC. Compared with SSP, the peak position of SSP-CHC is increased from 3436.16 cm -1 Offset to 3448.69 cm -1 , indicating that there is a hydrogen bond-induced interaction between SSP and CHC, which may be attributed to the better binding of protein and polysaccharide during glycosylation. -1 、1600-1500 cm -1 and 1300-1200 cm -1 The peaks at 1592.18 cm-1 correspond to amide I band (C=O stretching vibration), amide II band (NH bending and CN stretching), and amide III band (CN stretching and NH bending). The peak of amide I region in SSP-CHC has no obvious change, and the peak of amide II region has increased from 1592.18 cm-1 to 1592.18 cm-1. -1 Move to 1629.77 cm -1 The peak of amide III region is from 1235.08 cm -1 Move to 1243.43 cm -1 , the peak shifts to a higher wavelength, indicating that the inter- and intra-molecular bonds are broken and the secondary structure of the protein is aggregated.

[0026] The differential scanning calorimetry analysis of SSP-CHC is shown in Figure 3 As shown in D, the maximum peaks of SSP and SSP-CHC appear at 118.57 ℃ and 153.0 ℃, respectively, and the enthalpy values ​​of SSP and SSP-CHC are 47.8 J / g and 18.0 J / g, respectively, indicating that the introduction of CHC increases the electrostatic repulsion and steric hindrance in the complex, thereby increasing the stability and thermodynamic stability of the SSP-CHC structure. Denaturation temperature (Td) is used to describe the thermal stability of proteins.

[0027] The scanning electron microscopy image of SSP-CHC is shown in Figure 3 As shown in Figure E, SSP is an uneven spherical shape with an inwardly concave surface and is in an aggregated state, while the SSP-CHC composite is blocky and has a looser and more porous surface structure than SSP, a larger contact area, and is easy to form a more stable and continuous three-dimensional network structure. Example 2: Preparation of sunflower seed butter

[0028] The fried sunflower kernels obtained in Example 1 were put into a multifunctional grinder for 20 minutes to obtain sunflower seed paste; 1% (mass percentage) of SSP-CHC was added to the sunflower seed paste, and then homogenized and stirred at 80° C. for 25 minutes, and hot canned to obtain sunflower seed butter (1% SSP-CHC); sunflower seed butter (CK) prepared by electric-frying sunflower kernels without adding SSP-CHC and sunflower seed butter (IR) prepared by infrared-frying sunflower kernels without adding SSP-CHC 700W-180℃ ) as control; the basic properties of the sunflower seed butter are as shown in the attached Figure 4 and Table 1. Example 3: Preparation of sunflower seed butter

[0029] The roasted sunflower kernels obtained in Example 1 were put into a multifunctional grinder for 20 minutes to obtain sunflower seed paste; 2% (mass percentage) of SSP-CHC was added to the sunflower seed paste, and then homogenized and stirred at 80° C. for 25 minutes, and hot canned to obtain sunflower seed paste (2% SSP-CHC); the basic properties of the sunflower seed paste are as shown in the attached Figure 4 and Table 1. Example 4 Preparation of sunflower seed butter

[0030] The roasted sunflower kernels obtained in Example 1 were put into a multifunctional grinder for 20 minutes to obtain sunflower seed paste; 3% (mass percentage) of SSP-CHC was added to the sunflower seed paste, and then homogenized and stirred at 80° C. for 25 minutes, and hot canned to obtain sunflower seed paste (3% SSP-CHC); the basic properties of the sunflower seed paste are as shown in the attached Figure 4 As shown in Table 1: Table 1 Basic properties of sunflower seed butter prepared in different embodiments ; Span, particle size distribution width. From Table 1, we can see that 700W-180 Compared with 1% ~ 3% SSP-CHC, the centrifugal oil separation rate, acid value and peroxide value of sunflower seed butter are reduced, while the span value and shelf life are increased, indicating that the addition of SSP-CHC can be evenly dispersed in the sunflower seed butter to form a uniform gel network, which can then fix the particle components in the butter and adsorb oil droplets, thereby inhibiting the oil separation and oxidation of sunflower seed butter.

[0031] Combination Figure 4 The sunflower seed butter samples prepared in Examples 2 to 4 were analyzed as follows: Macro image of sunflower seed butter Figure 4 As shown in A, the CK sunflower seed butter that has not been infrared-fried is milky white, while the sunflower seed butter that has been infrared-fried is orange-yellow. As the amount of SSP-CHC added increases, the color of the sunflower seed butter gradually becomes lighter.

[0032] Microscopic image of sunflower seed butter Figure 4 As shown in Figure B, compared with CK sunflower seed butter that has not been infrared fried, the oil droplets of sunflower seed butter that has been infrared fried are more evenly distributed. As the amount of SSP-CHC added increases, the size of the oil droplets gradually decreases and the distribution becomes more even. It is speculated that SSP-CHC with a large surface area improves the cohesion and oil adsorption capacity of the protein network, forming a stable network structure that is conducive to combining protein, cellulose and oil in the sauce.

[0033] The particle size distribution of sunflower seed butter is shown in the figure below. Figure 4 As shown in Figure C, the particle size histogram of sunflower seed butter with 1%–3% SSP-CHC showed a trimodal distribution. (4,3) and D (3,2) The D of sunflower seed butter after infrared frying is 98.34 μm and 17.89 μm respectively. (4,3) From 61.93μm to 29.26μm, D (3,2) From 15.30μm to 7.38μm. According to Newton's viscosity law, smaller particle size can reduce the sedimentation rate of sunflower seed butter and prevent oil precipitation.

[0034] The shear stress-shear frequency flow curve of sunflower seed butter is as follows: Figure 4 As shown in D, the shear stress of all sunflower seed butters gradually increases with the increase of shear frequency, which is consistent with the law of pseudoplastic fluid. With the addition of 1%-3% SSP-CHC, the shear stress increases. The shear stress required for CK sunflower seed butter that has not been infrared fried, sunflower seed butter that has been infrared heated, and sunflower seed butter with different amounts of SSP-CHC added also gradually increases. It is speculated that this may be because infrared heat treatment and the addition of SSP-CHC enhance the molecular interaction force of sunflower seed butter, and sunflower seed butter.

[0035] The apparent viscosity-shear frequency curve of sunflower seed butter is as follows Figure 4 As shown in Figure E, the viscosity of all sunflower seed butters decreases with the increase of shear frequency, indicating that the samples are pseudoplastic fluids. With the addition of 1%-3% SSP-CHC, the apparent viscosity of sunflower seed butter increases. When the shear frequency is greater than 10 s -1 When the amount of SSP-CHC added increases, the apparent viscosity of the sunflower seed butter samples tends to be stable. With the increase of SSP-CHC addition, a denser network structure is formed, thereby increasing the apparent viscosity of the sunflower seed butter.

[0036] Storage modulus / loss modulus-frequency sweep diagram of sunflower seed butter Figure 4As shown in Figure F, G' (elastic modulus) and G" (viscous modulus) of all sunflower seed butters increase with the increase of shear frequency, and G">G', which indicates that their viscosity is higher than their elasticity. In addition, there is no intersection between G" and G', indicating that each butter has the characteristics of a macromolecular solution. With the increase of SSP-CHC addition, G' and G" of sunflower seed butter increase, indicating that the formation of SSP-CHC is conducive to the formation of a stable network structure, increasing the viscosity and consistency of sunflower seed butter, promoting strong interaction between particles in the butter, blocking oxygen, and improving the storage stability of sunflower seed butter.

[0037] In summary, the present invention utilizes the complex formed by protein and polysaccharide, which has both good emulsification, coagulation, interface adsorption and other functional properties of protein, and excellent water holding capacity, thickening and other processing characteristics of polysaccharide, and carries out the directional design of sunflower seed protein and chitosan, and prepares the sunflower seed protein-chitosan hydrochloride complex. Based on the unique stable colloid and spatial network barrier function of protein-polysaccharide complex, the present invention uses the comprehensive thermal effect of mid-infrared hot frying process to remove the endocarp of sunflower kernel, degrade chlorogenic acid and form flavor, and obtains a clean label sunflower seed sauce with high antioxidant activity, strong stability and food production compliance, which has broad application prospects and good social and economic effects.

[0038] The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the scope of protection determined by the claims submitted for the present invention.

Claims

1. A method for preparing a sunflower seed protein-chitosan hydrochloride complex, characterized in that: The method comprises: S1. Preparation of sunflower seed protein (SSP) stock solution: SSP was slowly added into deionized water at a mass volume ratio of 0.45 to 0.50:100, followed by stirring at room temperature of 20 to 25°C and 150 to 200 rpm for 2 to 2.5 hours, and then subjected to ultrasonic treatment at a power of 100 to 125 kHz for 20 to 25 minutes to obtain an SSP stock solution; S2. Preparation of chitosan hydrochloride (CHC) stock solution: CHC was slowly added into deionized water at a mass volume ratio of CHC to deionized water of 0.45-0.50:100, followed by stirring at room temperature of 20-25°C and 150-200 rpm for 2-2.5 hours, and then subjected to ultrasonic treatment at a power of 100-125 kHz for 20-25 minutes to obtain a CHC stock solution; S3. Preparation of SSP-CHC: First, the CHC stock solution is slowly added to the SSP stock solution in a mass ratio of SSP stock solution to CHC stock solution of 3 to 4:1, and stirred overnight at room temperature of 20 to 25°C and 100 to 200 rpm; then, it is placed in a 4 to 8°C environment for cold treatment for 20 to 24 hours; then, the pH value of the mixed solution is adjusted to 4.0 to 4.5 with 0.1 M HCl; after incubation at 75 to 80°C for 7.5 to 8.0 hours, it is placed in an ice water bath for cooling for 0.5 to 1.0 hour, placed in a dialysis bag with a molecular weight cutoff of 25 kDa, dialyzed in running tap water at room temperature for 24 hours, and finally freeze-dried to constant weight to obtain an SSP-CHC complex.

2. The method for preparing a sunflower seed protein-chitosan hydrochloride complex according to claim 1, characterized in that: The sunflower seed protein is prepared by the following method: (1) Mid-infrared frying of sunflower seed kernels The moisture content of the sunflower seed kernels is adjusted to 10-12%, and the kernels are placed in a mid-infrared frying barrel, and fry for 4-5 minutes at an infrared power of 700-800W, so that the surface temperature of the kernels reaches 180-200°C, and the kernels are immediately placed in a vibrating screen for shaking and air separation to remove the inner seed coat of the sunflower seeds, thereby obtaining fried sunflower seed kernels; (2) Preparation of sunflower seed protein (SSP) The roasted sunflower kernels were crushed and defatted with n-hexane-methanol v:v=9:1, filtered, and the retentate was collected. The retentate was placed in a ventilated place overnight to obtain sunflower seed powder; the sunflower seed powder was dispersed in a NaCl aqueous solution with a solid-liquid ratio of 1:18~20, and ultrasonic-assisted extraction was performed at 40±1℃ for 3.0h to obtain an extract; the extract was centrifuged at 10000 r / min for 20min, and the supernatant was collected; ammonium sulfate powder was slowly added to the supernatant to make the ammonium sulfate saturation reach 65~75%, and the mixture was allowed to stand at room temperature for 30min, and then centrifuged at 100000 r / min for 20min, and the precipitate was collected to obtain precipitate A; precipitate A was dispersed in a 0.01M phosphate buffer with a mass volume ratio of 1:10, and placed in an environment of 4~8℃ for 24h, and then centrifuged at 100000 r / min for 20min. min, collect the precipitate B; desalt the precipitate B by ultrafiltration and then dry it in vacuum to constant weight to obtain SSP.

3. The method for preparing a sunflower seed protein-chitosan hydrochloride complex according to claim 1, characterized in that: The basic characteristic parameters of the SSP-CHC are as follows: SSP-CHC is a cream-yellow powder, with a grafting degree of 57.0 ± 2.0%, a particle size of 360 ± 10 nm, a Zeta potential of 43 ± 2.5 mv, a PDI (Polymer Dispersity Index) of 0.40 ± 0.05, a fluorescence intensity of 115.0 ± 13.0, a surface hydrophobicity of 140.0 ± 10.0, a denaturation temperature of 153.0 ± 5.0 °C, an enthalpy of 18.0 ± 2.0 J / g, and the contents of α-helix, β-fold, β-turn and random coil in the secondary structure are 12.0 ± 0.5%, 32.5 ± 1.2%, 43.5 ± 2.1% and 11.5 ± 0.6%, respectively.

4. A sunflower seed protein-chitosan hydrochloride complex, characterized in that: The sunflower seed protein-chitosan hydrochloride complex is prepared by the method according to any one of claims 1-3.

5. Use of the sunflower seed protein-chitosan hydrochloride complex prepared according to any one of claims 1 to 3 in the preparation of sunflower seed paste.

6. A sunflower seed paste, characterized in that: The sunflower seed paste contains the sunflower seed protein-chitosan hydrochloride complex prepared by the method according to any one of claims 1 to 3.

7. A method for preparing sunflower seed paste, characterized in that: The method comprises: (1) Put the roasted sunflower seed kernels into a multifunctional grinder or a stone mill and grind them for 15 to 20 minutes to obtain a sunflower seed paste with a particle size of 60 to 65 μm; (2) Add 1 to 3% by weight of a sunflower seed protein-chitosan hydrochloride complex (SSP-CHC) prepared by the method described in any one of claims 1 to 3 to the sunflower seed paste, then homogenize and stir at 75 to 80° C. for 25 to 30 minutes, and hot-can to obtain sunflower seed paste.

8. The method for preparing sunflower seed paste according to claim 7, characterized in that: The basic properties of the sunflower seed butter are as follows: the sunflower seed butter is orange-yellow, and the average particle size of the butter body (D 4,3 ) and area average particle size (D 3,2 ) are 30 ~45 μm and 8 ~ 12 μm respectively. The texture characteristic parameters of hardness, consistency, cohesion and viscosity are 300 ~ 600 g, 2000 ~ 4000 g / sec, -800 ~ -1700g and -600 ~ -1400 g.sec respectively. The centrifugal oil separation rate is 6.5 ~ 8.5%. The acid value and peroxide value are 0.90 ~ 1.10 and 0.85 ~ 0.92 respectively. The shelf life at room temperature is 90 ~ 120 days.

Images