Preparation and application of distiller's arabinoxylan-high-tannin protein complex

Abstract

The present disclosure belongs to the technical field of functional ingredient extraction, and provides preparation and application of a distiller's grains arabinoxylan-sorghum prolamin complex. The preparation method comprises the following steps: drying and crushing distiller's grains, removing oil and starch, obtaining a suspension in an alkaline environment through infrared irradiation, stirring, shearing and centrifuging the suspension to obtain a supernatant, adjusting the supernatant to be acidic, centrifuging the supernatant again, alcohol precipitation, drying to obtain an extract, and coupling reaction at a proper temperature and humidity. The present disclosure also discloses the complex prepared by the above method, an emulsifier comprising the complex, and application of the emulsifier in the fields of food and cosmetics. The present disclosure adds infrared-assisted extraction, enhances dissolution and extraction of polysaccharides and sorghum prolamin, shortens extraction time and improves extraction rate; and further enhances emulsification through a dry heating method. The prepared complex has good water solubility, fast dissolution speed and strong emulsifying capacity, and can be used as a natural emulsifier in various scenarios.

Description

Technical Field

[0001] This disclosure relates to the field of functional component extraction technology, and in particular to the preparation and application of distillers' grains arabinoxylan-sorghum prolysin complex. Background Technology

[0002] Baijiu (Chinese liquor) lees are the main solid residue produced during grain fermentation and distillation in baijiu production, accounting for approximately 80-85% of the total brewing byproducts. Currently, they are mainly used as low-value nutrients in animal feed, biogas production, and organic fertilizer production. Baijiu lees contain a large amount of unutilized cellulose, protein, organic acids, vitamins, and other nutrients, resulting in resource waste. With increasing environmental awareness and technological advancements, people are constantly seeking high-value utilization of grain processing byproducts such as lees. Arabicaxylan, a major soluble dietary fiber in grain bran, possesses excellent emulsifying properties and good rheological characteristics, showing broad application prospects in the food and cosmetics industries. Furthermore, sorghum prolysin in baijiu lees is also a functionally valuable component, capable of film formation and encapsulation. Baijiu brewing involves multiple processing steps, including cooking, fermentation, and distillation. During the production of baijiu (Chinese liquor), high temperature, acidic conditions, and extensive microbial enzymatic hydrolysis can promote the formation of arabinoxylan-sorghum prolysin complexes through non-covalent interactions (such as hydrogen bonds and hydrophobic interactions) and covalent linkages (Maillard reactions).

[0003] Currently, alkaline extraction is commonly used to extract arabinoxylan from grains. This method disrupts the chemical bonds between arabinoxylan and other cell wall components (such as lignin and cellulose), breaking the complex structure of the cell wall and releasing the insoluble, covalently cross-linked arabinoxylan, which then dissolves in an alkaline solvent, achieving efficient extraction. Simultaneously, some sorghum prolysins are also extracted from baijiu (Chinese liquor) lees in the form of complexes. These complexes exhibit good emulsifying stability, primarily due to steric hindrance and electrostatic repulsion between oil droplets. Specifically, the polysaccharide chains provide steric stability through electrostatic repulsion, while the protein components adsorb onto the surface of the hydrophobic oil droplets. This property makes them suitable for stabilizing dairy beverages and salad dressings in the food industry, and for improving the homogeneity and shelf life of lotions and creams in the cosmetics field, significantly reducing the risk of product separation, and possessing the potential to replace synthetic emulsifiers. However, the extraction rate and emulsifying stability of naturally formed polysaccharide-protein complexes extracted from baijiu lees still need improvement. Summary of the Invention

[0004] This disclosure provides the preparation and application of a distillers' grains arabinoxylan-sorghum prolysin complex, in order to at least solve the above-mentioned technical problems existing in the prior art.

[0005] According to a first aspect of this disclosure, a method for preparing a distillers' grains arabinoxylan-sorghum prolysin complex is provided, comprising the following steps:

[0006] S1: Dry and crush the lees to obtain the raw material;

[0007] S2: The raw materials are subjected to degreasing and destarching treatment;

[0008] S3: The material after starch removal in step S2 is subjected to infrared irradiation for 30-60 min at a pH of 10.5-12 and a temperature of 50-70℃ to obtain a suspension.

[0009] S4: Heat the suspension to 80-90°C in a water bath, stir, mechanically shear and centrifuge, and take the first supernatant; adjust the pH of the first supernatant to 3.5-4.0, let it stand, centrifuge and collect the second supernatant; precipitate the second supernatant with alcohol and dry it to obtain the extract;

[0010] S5: The extract is subjected to a coupling reaction at 55~70℃ and 60~70% humidity to obtain the arabinoxylan-sorghum prolysin complex.

[0011] Specifically, the addition of infrared-assisted extraction during the extraction process enhances the dissolution and extraction of arabinoxylan and sorghum prolysin, shortening the extraction time and increasing the extraction rate. This is because radiation with an emission wavelength range of 0.78–1000 μm can excite atoms and molecules in the grain raw material. Atomic vibrations lead to increased temperature, resulting in evaporation of liquid cell contents and tissue disruption, making it easier for polysaccharides and proteins to be released into the external medium (solvent) during extraction. In the final step of extraction, dry heating further enhances emulsification. This is because after mixing the polysaccharides and proteins, heating under controlled conditions allows them to chemically bond through the Maillard reaction, forming a complex and strengthening the bond between them.

[0012] In one embodiment, the lees are selected from at least one of baijiu lees, beer lees, huangjiu lees, and wine lees.

[0013] In a preferred embodiment, the lees are selected from baijiu (Chinese liquor) lees.

[0014] Specifically, the main raw material for distillers' grains is sorghum, which is a natural enrichment source of xylan and prolysins. These are widely available and inexpensive. The complex matrix of distillers' grains (such as rice husks and residual metabolites) can be effectively separated through a wet process involving heating, shearing, acid-base regulation, and centrifugation. Combining this with technologies such as infrared irradiation and dry heating can further enhance the extraction efficiency and binding strength of arabinoxylan and sorghum prolysins.

[0015] The fermentation process of baijiu plays a crucial positive role in the natural formation and subsequent extraction and utilization of arabinoxylan-sorghum prolysin in the lees. Specifically: 1. Baijiu fermentation (especially strong-aroma and sauce-aroma types) relies on complex microbial communities (such as Bacillus, yeast, and mold). These microorganisms chemically modify arabinoxylan and prolactin in sorghum raw materials through metabolic activities, creating conditions for their combination: Xylanase secreted by microorganisms degrades long-chain arabinoxylan in sorghum cell walls into oligosaccharide fragments, exposing more active groups such as hydroxyl and acetyl groups. These groups are the core sites for subsequent hydrogen bonds and hydrophobic bonds with prolactin. Compared with unfermented raw grains, the binding activity of arabinoxylan is significantly improved after fermentation. Proteases produced by microbial metabolism (such as alkaline proteases) perform limited hydrolysis on sorghum prolactin (mainly α-prolactin), breaking some of the tight β-sheet structure and exposing more hydrophobic sites and amino groups. These sites can form stronger non-covalent bonds with the hydroxyl groups of arabinoxylan, and even induce some covalent bonds at high temperatures in the later stages of fermentation. 2. The multi-stage environmental changes (temperature, humidity, pH, oxygen) during the fermentation of baijiu will promote the interaction between arabinoxylan and prolactin from a physical perspective, forming a more stable complex: (1) The temperature gradient during fermentation, from low-temperature saccharification (20~30℃) to medium-temperature alcohol production (30~40℃) to high-temperature aging (50~65℃), will promote the molecular thermal motion of arabinoxylan and prolactin. At low temperatures, the two will initially combine through weak interactions, and at high temperatures, the molecular kinetic energy will increase, prompting the active groups to come into full contact and form a tighter complex structure; (2) The initial pH of sorghum raw material is about 6.5. ~7.0, the organic acids produced by microbial metabolism during fermentation will cause the pH of the system to drop to 4.0~5.0, while the isoelectric point (pI) of alcohol-soluble protein is about 6.0~6.5. When the pH of the system is lower than pI, alcohol-soluble protein is positively charged and can further bind with negatively charged arabinoxylan through electrostatic attraction, thus strengthening the stability of the complex; (3) During fermentation, sorghum grains absorb water and swell, and microbial mycelia intertwine to form a dense fermentation substrate. This structure will restrict the free diffusion of arabinoxylan and alcohol-soluble protein, forcing the two to interact more easily in a local high-concentration environment, thus reducing component loss.3. Baijiu fermentation not only promotes the formation of arabinoxylan-glucan but also provides a natural pretreatment of the lees matrix, facilitating subsequent infrared extraction and dry heating: microorganisms consume starch and some fat in sorghum, reducing the interference of starch gelatinization and fat emulsification on the separation of arabinoxylan-glucan during subsequent extraction; cellulase and pectinase secreted by microorganisms partially degrade the supporting structures such as cellulose and pectin in the sorghum cell walls, increasing the cell wall pores. During subsequent infrared irradiation, infrared energy can more easily penetrate the matrix and directly act on arabinoxylan and glucan, accelerating the dissociation and release of the complex; during dry heating, heat is also transferred more evenly, avoiding local overheating and denaturation caused by the density of the raw grain matrix.

[0016] In one embodiment, the drying temperature in step S1 is 50~60°C.

[0017] In one embodiment, the degreasing in step S2 includes the following steps: mixing the raw material and an organic solvent, filtering under vacuum, and drying at 45-50°C for 6-10 hours.

[0018] Specifically, the mass-to-volume ratio of the raw material and the organic solvent is 0.1~0.167 g / mL.

[0019] Specifically, the organic solvent is selected from at least one of n-hexane, petroleum ether, and ethyl acetate.

[0020] Specifically, the mixing speed is 450~550 r / min, and the time is 1~1.5 h.

[0021] In one embodiment, the destarch removal in step S2 includes the following steps: adding the degreased material to boiling water, enzymatically hydrolyzing it with α-amylase in a water bath at 80~90℃ for 25~40 min to obtain a suspension; centrifuging the suspension, collecting the precipitate, and washing it.

[0022] Specifically, the α-amylase accounts for 0.3 to 0.75% of the volume of the boiling water.

[0023] Specifically, the enzyme activity of the α-amylase is 18000~25000 u / mL.

[0024] Specifically, the centrifugation speed is 4500~6000 r / min, and the time is 10~20 min.

[0025] Specifically, the washing is performed using water, and the washing is performed 3 to 4 times.

[0026] In one embodiment, step S3 involves adding the destarched material to water, adjusting the pH of the solution to 10.5-12 with an alkaline solution, and heating it to 50-70°C.

[0027] Specifically, the material-to-liquid ratio is 75~150 g / L. That is, 75~150 g of the destarched material is added to each liter of water.

[0028] Specifically, the mass concentration of the alkaline solution is 35-55%, and the alkaline solution is selected from any one of sodium hydroxide, calcium hydroxide, and potassium hydroxide.

[0029] Specifically, the role of the alkaline solution is to create an alkaline environment, decompose lignin, and break the hydrogen and ester bonds between arabinoxylan and other components of the plant cell wall (such as cellulose and lignin), allowing arabinoxylan to dissolve in the liquid. Extraction then proceeds through acid neutralization and alcohol precipitation. Heating to 50-70°C increases the solubility of arabinoxylan in the solution, making it easier to extract and increasing the extraction rate.

[0030] In one embodiment, the electrical power during infrared irradiation in step S3 is 300~400 W, and the wavelength is 3~10 μm.

[0031] In one embodiment, step S4 involves stirring at 500-700 r / min for 20-40 min; mechanically shearing at 10000-12000 r / min for 40-60 min; centrifuging at 4500-6000 r / min for 10-20 min, and then taking the first supernatant.

[0032] In one embodiment, in step S4, the pH of the first supernatant is adjusted to 3.5-4.0 with 10-12 mol / L hydrochloric acid, allowed to stand for 8-15 min, and then centrifuged at 4500-6000 r / min for 25-40 min before collecting the second supernatant.

[0033] In one embodiment, during alcohol precipitation in step S4, an alcohol reagent is added, mixed, allowed to stand, and then vacuum filtered to obtain a precipitate; the precipitate is added to the alcohol reagent and stirred for 5-10 minutes, repeated twice; the final precipitate is dried to obtain the extract.

[0034] Specifically, in step S4, when performing alcohol precipitation, the volume of the added alcohol reagent is 2 to 4 times the volume of the second supernatant; the mixing speed is 200 to 300 r / min, the time is 10 to 15 min, and the standing time is 10 to 12 h.

[0035] Specifically, the alcohol reagent includes either anhydrous ethanol or isopropanol.

[0036] Specifically, the drying temperature is 45~55℃ and the time is 6~10 h.

[0037] In one embodiment, the coupling reaction in step S5 takes 12 to 24 hours.

[0038] In one embodiment, step S5 involves freeze-drying the arabinoxylan-sorghum prolysin complex after the coupling reaction.

[0039] According to a second aspect of this disclosure, a distillers' grains arabinoxylan-sorghum prolysin complex prepared according to the above-described preparation method is provided, wherein arabinoxylan and sorghum prolysin are linked by electrostatic interaction and covalent bonds.

[0040] Specifically, the aforementioned complex contains a small amount of ash (mainly salts produced during the extraction process) and water (mainly in the form of bound water in the complex, not completely dried).

[0041] According to a third aspect of this disclosure, an emulsifier is provided comprising the above-described distillers' grains arabinoxylan-sorghum prolysin complex.

[0042] According to the fourth aspect of this disclosure, the emulsifier is used in the food and cosmetic fields.

[0043] Specifically, when used in the food industry, the emulsifier includes, but is not limited to, beverages, dairy products, and baked goods. When used in the cosmetics industry, the emulsifier can be used as a stabilizer for emulsion products.

[0044] According to one possible implementation of this disclosure, at least the following beneficial effects are achieved:

[0045] This disclosure uses distiller's grains as raw material to transform them into high-value-added functional materials, thereby enhancing the economic value of distiller's grains. Moreover, as a free / low-cost byproduct, distiller's grains can reduce the cost of compound preparation compared to extracting directly from sorghum raw materials, thus significantly improving the product's market competitiveness.

[0046] This disclosure employs a combined infrared irradiation and dry heating process to extract a polysaccharide-protein complex from distiller's grains that exhibits good water solubility, rapid dissolution, and strong emulsifying ability. Infrared irradiation accelerates component dissolution through molecular vibration, improving extraction efficiency compared to traditional alkaline extraction methods. Dry heating strengthens the chemical bond between the two components, resulting in a significantly stronger bond compared to natural mixing. The complex of this disclosure is chemically bonded, rather than physically mixed, exhibiting significantly improved structural stability compared to traditional physical mixtures (which are prone to stratification and weak bonding), providing a robust molecular basis for subsequent applications.

[0047] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0048] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:

[0049] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0050] Figure 1 The particle size distribution diagrams of the oil-in-water emulsions prepared from the arabinoxylan-sorghum prolysin complexes of Examples 1, 4, Comparative Examples 1 and 2 of this disclosure are shown.

[0051] Figure 2 The particle size distribution of the oil-in-water emulsions prepared from the arabinoxylan-sorghum prolysin complexes of Example 1 and Comparative Examples 1-3 of this disclosure at different temperatures is shown.

[0052] Figure 3 The diagram shows the changes in appearance of the oil-in-water emulsions prepared from the arabinoxylan-sorghum prolysin complex of Example 1 and Comparative Examples 1-3 after being treated and stored at different temperatures for 21 days.

[0053] Figure 4 The average particle size distribution of the oil-in-water emulsions prepared by the arabinoxylan-sorghum prolysin complex of Example 1 and Comparative Examples 1-3 of this disclosure under different pH conditions is shown.

[0054] Figure 5 The amino acid composition test results of the arabinoxylan-sorghum prolysin complex of Example 1 and Comparative Example 1 of this disclosure are shown in the figure.

[0055] Figure 6 Scanning electron micrographs of the arabinoxylan-sorghum prolysin complexes prepared in Examples 1-4 and Comparative Examples 1-3 of this disclosure are shown; the scale bar is 1 μm. Detailed Implementation

[0056] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0057] Example 1

[0058] This embodiment prepared a distillers' grains arabinoxylan-sorghum prolyl complex, as detailed below:

[0059] (1) The lees of the liquor were obtained by a liquor company in Pingdingshan, Henan Province, through the brewing process of light-aroma Daqu liquor. The specific steps include: a. High-quality Northeast red sorghum (japonica sorghum) is used as the main raw material. After cleaning and crushing, the raw material is moistened with high-temperature water at a temperature of ≥95℃. The amount of moistening water is 70~75% of the weight of sorghum. The soaking time is 24h, so that the moisture content of the raw material finally reaches 48~52%. After moistening, the raw material is steamed and gelatinized for 30min, steamed at 45℃ for 60min, and steamed again at 45℃ for 45min. At this time, the gelatinization rate of the sorghum raw material reaches 90%. b. "Three-color koji" made by mixing barley, wheat and peas in a specific mass ratio (clean stubble koji: post-fire koji: red heart koji is 3:4:3) is used as the saccharification and fermentation agent. After cooling the steamed sorghum raw material to the inlet temperature (9-11℃), add the above-mentioned Daqu (a type of starter culture) at 20% of the sorghum weight, and simultaneously mix in 5% (by weight of sorghum) of rice husks as a filler, and stir thoroughly. The mixed material is then placed in a ceramic vat (washed three times with hot water at ≥95℃ and drained before use) and fermented using a pure grain solid-state fermentation method in a closed environment. The main fermentation cycle is 25-30 days, with the core fermentation temperature controlled at 25-30℃. The fermentation temperature curve exhibits a characteristic of "slow rise at the beginning, stable in the middle, and slow decline at the end." c. The fermented mash is distilled in a solid state to obtain the first batch of liquor. After distillation, the mash is removed from the still, spread out to a suitable temperature, and then Daqu powder (2-3% of the sorghum weight) is added before being placed back into the vat for a second round of fermentation. The mash after the second round of fermentation is distilled in a second solid state to obtain the second batch of liquor. The final solid residue produced after this distillation is used as the baijiu lees in this embodiment. The lees contain less than 10% starch, have an acidity (calculated as acetic acid) of 1.5 to 3.0 mmol / 10g, and a water content of 60 to 68%.

[0060] (2) The baijiu lees obtained in step (1) are dried in an oven at 50°C, then crushed by a high-speed pulverizer and passed through a 200-mesh sieve to obtain the raw material.

[0061] (3) Add 300 g of the raw material obtained in step (2) and 2 L of n-hexane to a 5 L beaker, stir at 500 r / min for 1 h, filter under vacuum, and place in an oven at 45 °C for 8 h to dry.

[0062] (4) Add the degreased material to 2 L of boiling distilled water, and then enzymatically hydrolyze it for 30 min with 15 mL of heat-resistant α-amylase (enzyme activity of 20000 u / mL) at 85℃ in a water bath to remove starch and obtain a suspension. Centrifuge the suspension at 5000 r / min for 15 min and collect the precipitate; wash the precipitate three times with distilled water.

[0063] (5) Add the destarched material to 3 L of distilled water, adjust the pH of the solution to 11.5 with 50% sodium hydroxide, heat to 65℃, and irradiate at a distance of 1 cm from the black ceramic infrared emitter for 60 min to obtain a suspension; wherein the electric power of the infrared irradiation is 400 W and the wavelength is 3~10 μm.

[0064] (6) Heat the suspension from step (5) to 85°C in a water bath and stir at 600 r / min for 20 min; then use a high-speed homogenizer to mechanically shear at 11000 r / min for 1 h. After cooling, centrifuge at 5000 r / min for 15 min and collect the supernatant. Adjust the pH of the supernatant to 4.0 with 11 mol / L hydrochloric acid, let it stand for 10 min, and then centrifuge at 5000 r / min for 30 min and collect the supernatant again.

[0065] (7) Add 2 volumes of anhydrous ethanol to the supernatant obtained in step (6), stir with a stirrer at 200 r / min for 10 min, and let stand for 12 h. Vacuum filter to obtain the precipitate, add 600 mL of anhydrous ethanol to the precipitate and stir for 8 min, repeat twice. Dry the final precipitate in a vacuum drying oven at 45℃ for 8 h to obtain the extract.

[0066] (8) The extract from step (7) was reacted at 65°C and 65% humidity for 18 h, and then cooled to room temperature in a desiccator to stop the coupling reaction. After freeze-drying, the arabinoxylan-sorghum prolysin complex was obtained.

[0067] The content of arabinoxylan was determined by high performance liquid chromatography (HPLC): 10 mg of sample was weighed into a pressurized tube, 4 mL of 4 mol / L trifluoroacetic acid was added, the tube was sealed after purging with nitrogen, and hydrolyzed in an oven at 110 °C for 6 h. After cooling, 500 μL of methanol was added, and the mixture was rotary evaporated to remove excess trifluoroacetic acid. 5 mL of distilled water was added to dissolve the monosaccharides. 200 μL of the hydrolysate was taken, and 200 μL each of 0.5 mol / L PMP methanol solution and 0.3 mol / L NaOH solution were added and mixed using a vortex mixer. After heating in a water bath at 70 °C for 1 h, 200 μL of 0.3 mol / L HCl solution was added. 1 mL of chloroform was added for extraction, and this process was repeated 2-3 times to remove excess PMP. The resulting aqueous phase was filtered through a 0.22 μm filter membrane, injected into a vial using a syringe, and analyzed for monosaccharide composition using HPLC. Chromatographic conditions: T3 column, mobile phase A was acetonitrile, mobile phase B was 0.1 mol / L ammonium acetate solution, detection wavelength was 250 nm, flow rate was 1 mL / min, injection volume was 10 μL, and column temperature was 30℃. Elution ratio was 19% for phase A and 81% for phase B. A standard curve was prepared using xylose, arabinose, rhamnose, glucuronic acid, galacturonic acid, glucose, and galactose as standards. The arabinoxylan content was the sum of xylose and arabinose.

[0068] The content of sorghum prolamin was determined according to the Kjeldahl method in the national standard GB 5009.5-2025 "National Food Safety Standard - Determination of Protein in Food". Specifically, 1.000 g of sample was weighed and transferred to a dry 250 mL digestion tube. 0.4 g of copper sulfate, 6 g of potassium sulfate, and 20 mL of sulfuric acid were added. After gentle shaking, a small funnel was placed at the mouth of the tube, and the digestion tube was placed in a digestion furnace and heated until the reaction was complete, at which point the liquid was a clear blue color. After cooling, 50 mL of distilled water was added, and the entire process of adding liquid, distilling, titrating, and recording titration data was performed automatically using an automatic Kjeldahl nitrogen analyzer. The protein conversion factor F = 6.25.

[0069] Complex extraction rate (%) = (mass of extracted arabinoxylan - mass of sorghum prolysin complex) (g) / mass of dried baijiu lees (g) × 100%.

[0070] The three indicators were tested using the above method. The following examples and comparative examples were also tested using the same method, and will not be repeated hereafter. The final arabinoxylan-sorghum prolysin complex contained 68.14% arabinoxylan by mass and 15.89% sorghum prolysin by mass, with an extraction rate of 11.63%.

[0071] Example 2

[0072] This embodiment prepared a distillers' grains arabinoxylan-sorghum prolysin complex, which was prepared according to the method of Example 1, except that the infrared irradiation treatment time was 45 min.

[0073] The test results showed that the final arabinoxylan-sorghum prolysin complex contained 63.49% arabinoxylan and 14.50% sorghum prolysin, with an extraction rate of 9.82%.

[0074] Example 3

[0075] This embodiment prepared a distillers' grains arabinoxylan-sorghum prolysin complex, which was prepared according to the method of Example 1, except that the infrared irradiation treatment time was 30 min.

[0076] The test results showed that the final arabinoxylan-sorghum prolysin complex contained 60.41% arabinoxylan and 13.73% sorghum prolysin, with an extraction rate of 8.92%.

[0077] Example 4

[0078] This embodiment prepared a distillers' grains arabinoxylan-sorghum prolyl complex, as detailed below:

[0079] (1) The lees of the liquor (the same source and preparation method as in Example 1, which will not be repeated here) were dried in an oven at 50°C, then crushed by a high-speed pulverizer and passed through a 200-mesh sieve to obtain the raw material.

[0080] (2) Add 300 g of the raw material obtained in step (1) and 3 L of n-hexane to a 5 L beaker, stir at 500 r / min for 1 h, filter under vacuum, and place in an oven at 45 °C for 8 h to dry.

[0081] (3) Add the degreased material to 2 L of boiling distilled water, and then enzymatically hydrolyze it for 25 min at 85℃ with 10 mL of heat-resistant α-amylase (enzyme activity of 20000 u / mL) to remove starch and obtain a suspension. Centrifuge the suspension at 5000 r / min for 15 min and collect the precipitate; wash the precipitate three times with distilled water.

[0082] (4) Add the destarched material to 3 L of distilled water, adjust the pH of the solution to 10.5 with 50% sodium hydroxide, heat to 50℃, and irradiate at a distance of 1 cm from the black ceramic infrared emitter for 45 min to obtain a suspension; wherein the electric power of the infrared irradiation is 300 W and the wavelength is 3~10 μm.

[0083] (5) Heat the suspension from step (4) to 85°C in a water bath and stir at 600 r / min for 30 min; then use a high-speed homogenizer to mechanically shear at 11000 r / min for 1 h. After cooling, centrifuge at 5000 r / min for 15 min and collect the supernatant. Adjust the pH of the supernatant to 4.0 with 11 mol / L hydrochloric acid, let it stand for 10 min, and then centrifuge at 5000 r / min for 30 min and collect the supernatant again.

[0084] (6) Add 2 volumes of anhydrous ethanol to the supernatant obtained in step (5), stir with a stirrer at 200 r / min for 10 min, and let stand for 12 h. Vacuum filter to obtain the precipitate, add 600 mL of anhydrous ethanol to the precipitate and stir for 8 min, repeat twice. Dry the final precipitate in a vacuum drying oven at 45℃ for 8 h to obtain the extract.

[0085] (7) The extract from step (6) was reacted at 60°C and 60% humidity for 12 h, and then cooled to room temperature in a desiccator to stop the coupling reaction. After freeze-drying, the arabinoxylan-sorghum prolysin complex was obtained.

[0086] The test results showed that the final arabinoxylan-sorghum prolysin complex contained 57.64% arabinoxylan and 13.91% sorghum prolysin, with an extraction rate of 9.23%.

[0087] Comparative Example 1

[0088] This comparative example prepared an arabinoxylan-sorghum prolysin complex. The difference from Example 1 is that the infrared irradiation treatment step was omitted in this comparative example, and extraction was carried out by the usual alkaline extraction method. The rest is the same as in Example 1.

[0089] The test results showed that the final arabinoxylan-sorghum prolysin complex contained 56.53% arabinoxylan and 4.62% sorghum prolysin, with an extraction rate of 6.48%.

[0090] Comparative Example 2

[0091] This comparative example prepared an arabinoxylan-sorghum prolysin complex. The difference from Example 1 is that this comparative example omitted the dry heating coupling treatment step (i.e., step (7)). After vacuum drying, it is the final arabinoxylan-sorghum prolysin complex. The rest is the same as Example 1.

[0092] The test results showed that the final arabinoxylan-sorghum prolysin complex contained 61.68% arabinoxylan and 5.50% sorghum prolysin, with an extraction rate of 5.89%.

[0093] Comparative Example 3

[0094] This comparative example prepared an arabinoxylan-sorghum prolysin complex. The difference between this comparative example and Example 1 is that the raw material used in this comparative example is sorghum bran, while the rest is the same as in Example 1.

[0095] The test results showed that the final arabinoxylan-sorghum prolysin complex contained 51.69% arabinoxylan and 2.15% sorghum prolysin, with an extraction rate of 5.23%.

[0096] The test results of arabinoxylan content, sorghum prolysin content and complex extraction rate in the above embodiments and comparative examples are shown in Table 1 for intuitive comparison.

[0097] Table 1

[0098]

[0099] Test case

[0100] 1. The emulsification stability of the arabinoxylan-sorghum prolysin complexes prepared in Examples 1-4 and Comparative Examples 1-3 under different high-temperature conditions was tested, as follows:

[0101] A 3 wt% complex solution was prepared by dissolving arabinoxylan-sorghum prolysin complex in distilled water and stirring overnight. To inhibit microbial growth, sodium benzoate (0.1 wt%) and citric acid (0.3 wt%) were added to the solution. The complex solution was mixed with soybean oil at a ratio of 9:1 (w / w) to prepare an oil-in-water emulsion, which was then sheared at 15,000 rpm for 3 min using a high-speed homogenizer. Homogenization was performed three times at 400 bar using a high-pressure homogenizer. For thermal stability testing, the emulsion was heated in water baths at 70°C, 80°C, 90°C, and 100°C for 30 min. The particle size was then measured using a laser particle size analyzer, and the appearance of the emulsion was observed after 21 days of storage at room temperature to test the emulsification and thermal stability of the oil-in-water emulsion after different high-temperature treatments. An emulsion prepared without the complex was used as a blank control group. The results are as follows: Figure 1 , Figure 2 and Figure 3 As shown.

[0102] Figure 1The particle size distribution diagrams for the oil-in-water emulsions show that the peak values ​​of Examples 1 and 4 are concentrated in the 1.0–10.0 μm range, with high volume density peaks and narrow distribution ranges. This indicates that in the emulsions prepared in Examples 1 and 4, most oil droplets are concentrated in the small-particle-size range (i.e., small-particle-size oil droplets are not only numerous but also have a high volume proportion). This means that there are almost no large-particle-size oil droplets in the emulsions, resulting in extremely strong dispersion uniformity and excellent emulsification stability. Although the peak values ​​of Comparative Examples 1 and 2 are also in the 1.0–10.0 μm range, their volume density peaks are lower than those of Examples 1 and 4, and their distribution ranges are slightly wider. This indicates that in the emulsions of Comparative Examples 1 and 2, the volume proportion of small-particle-size oil droplets is lower, while the volume proportion of large-particle-size oil droplets is relatively higher, resulting in weaker emulsification uniformity and stability compared to Examples 1 and 4. The peak value of the blank comparison shifted significantly to the right, and the volume density distribution range was extremely wide (covering 1.0~100.0 μm or even wider), indicating that the volume ratio of large-diameter oil droplets in the blank emulsion was extremely high, and they were prone to rapid stratification due to gravity. This directly verified the key role of the complex in inhibiting oil droplet aggregation and maintaining emulsion stability.

[0103] Figure 2 The diagram shows the particle size distribution of the oil-in-water emulsions prepared in Example 1 and Comparative Examples 1-3 at different temperatures. It can be seen that the emulsion in Example 1 has the smallest average particle size when unheated, indicating that its complex can efficiently refine and uniformly disperse oil droplets at room temperature, with a significantly better initial emulsification effect than the comparative examples. The emulsions in Comparative Examples 1-3 generally have larger average particle sizes when unheated, with Comparative Example 3 having the largest average particle size. This indicates the crucial role of the baijiu lees raw material and the infrared irradiation + dry heating process in the initial emulsification effect: the pre-fermented complex precursor (arabinoxylan-sorghum prolysin) in the baijiu lees is more likely to form a stable emulsion, while sorghum bran, without fermentation modification, has a low complex binding degree and weak initial emulsification ability.

[0104] As the temperature increased from 70°C to 100°C, the average particle size of the emulsion in Example 1 increased only slightly, and there was no significant aggregation after high-temperature treatment at 100°C. This is because infrared irradiation enhanced the dissolution efficiency of arabinoxylan and sorghum prolysin in the complex. Dry heating formed a more stable covalently bonded structure through Maillard reaction. This strongly bonded complex is not easily dissociated at high temperatures and can continuously inhibit oil droplet aggregation and maintain emulsion stability through steric hindrance (polysaccharide chains) and electrostatic repulsion (protein dotted groups). The emulsion of Comparative Example 1 showed a rapid increase in average particle size above 70℃. Due to the lack of infrared irradiation, the complex was not fully dissolved, resulting in low protein content. At high temperatures, the weakly bound complex was prone to dissociation, and the oil droplets agglomerated after losing their stabilizing barrier. The emulsion of Comparative Example 2 showed a similar increase in average particle size at high temperatures to Comparative Example 1. Due to the lack of covalent bonding reinforcement, the complex was mainly physically mixed. At high temperatures, hydrogen bonds / hydrophobic interactions were easily destroyed, leading to a sharp drop in emulsion stability. The emulsion of Comparative Example 3 had the largest average particle size at 100℃ and may have stratified. This was because the sorghum bran did not contain a complex precursor formed during the fermentation process, resulting in low purity of the extracted complex, which almost lost its emulsion stabilizing ability at high temperatures.

[0105] In summary, infrared irradiation and dry heating are the core guarantees of thermal stability. Infrared irradiation increases the dissolution of the complex, while dry heating strengthens the binding strength. Both are indispensable. The high temperature and microbial enzymatic pretreatment in the brewing of baijiu cause arabinoxylan and sorghum prolysin in the lees to form weak binding precursors in advance, making it easier to form stable complexes during subsequent extraction.

[0106] Figure 3The graphs show the changes in appearance of the oil-in-water emulsions prepared in Examples 1 and Comparative Examples 1-3 after treatment and storage at different temperatures for 21 days. It can be seen that in Example 1, the emulsion remained a uniform white milky substance after all temperature treatments, without stratification or oil phase precipitation. This indicates that the complex in Example 1 can stably maintain the dispersion state of the oil-in-water emulsion under high-temperature treatment and long-term storage, demonstrating the strong emulsification and thermal stability of the complex prepared by the infrared irradiation + dry heating process. In Comparative Example 1, the emulsion appeared uniform without heating, but after treatment at 70°C and above, slight stratification (upper oil phase, lower water phase) gradually appeared, and the stratification became more pronounced at higher temperatures. This indicates that Comparative Example 1 lacked the infrared irradiation process, resulting in insufficient dissolution of the complex, low protein content, and easy dissociation of the complex at high temperatures, losing its stabilizing effect on oil droplets, thus leading to stratification. Even without heating, Comparative Example 2 showed significant emulsion stratification, which worsened after high-temperature treatment. This indicates that Comparative Example 2 lacked a dry heating process, and the complex was primarily physically mixed. At room temperature, it lost its emulsifying ability due to the disruption of hydrogen bonds / hydrophobic interactions, directly demonstrating that dry heating to enhance bonding is crucial for the stability of the complex. Comparative Example 3 showed severe emulsion stratification after all temperature treatments (a large oil phase on top and a clear aqueous phase at the bottom). This indicates that Comparative Example 3 used sorghum bran instead of baijiu lees, lacked baijiu fermentation pretreatment (microbial enzymatic hydrolysis, high-temperature modification), and had extremely low binding of the complex precursor (arabinoxylan-sorghum prolysin). The extracted complex had poor purity and was completely unable to stabilize the emulsion, proving that baijiu lees are the core compatibility advantage of this disclosure.

[0107] 2. The emulsification stability of the arabinoxylan-sorghum prolysin complexes prepared in Example 1 and Comparative Examples 1-3 under different pH conditions was tested, as follows:

[0108] Oil-in-water emulsions were prepared according to the method in Example 1. The pH of the oil-in-water emulsions was adjusted to 3, 6, 9, and 12 respectively using sodium hydroxide solution or hydrochloric acid. The particle size was then measured using a laser particle size analyzer. The results are as follows: Figure 4 As shown. Figure 4The results show that in Example 1, the average particle size of the emulsion was below 2 μm at pH 3, 6, 9, and 12, and the average particle size changed gradually at different pH values. This is because the complex in Example 1, through infrared irradiation and dry heating, formed a structurally stable covalent bond. The polysaccharide chains of arabinoxylan provided steric hindrance, and the charged groups of sorghum prolysin maintained oil droplet dispersion through electrostatic repulsion at different pH values, thus maintaining emulsion stability over a wide pH range and making it suitable for applications in acidic, neutral, and weakly alkaline environments. The average particle size of the emulsion in Comparative Example 1 was significantly larger than that of the emulsion in Example 1 at different pH values. This is because Comparative Example 1 did not have an infrared irradiation step, and the content of the effective components in the complex was lower than that in the emulsion of Example 1. Insufficient effective components reduced the adsorption of the complex at the oil droplet interface, weakening steric hindrance and electrostatic repulsion. Therefore, the average particle size of the emulsion in Comparative Example 1 was larger than that in Example 1, but a certain amount of the complex was still present. The emulsion of Comparative Example 2 showed a significantly larger average particle size than that of Example 1 at all pH levels. This is because Comparative Example 2 lacked a dry heating process, and the complex was mainly physically mixed without covalent reinforcement. Under acidic or alkaline conditions, hydrogen bonds and hydrophobic interactions were easily disrupted, leading to complex dissociation and a sharp decrease in emulsification stability. The emulsion of Comparative Example 3 showed a significantly larger average particle size than that of Example 1 at all pH levels. This indicates that the sorghum bran in Comparative Example 3 was not pretreated with fermentation. The arabinoxylan has a long-chain, highly crystalline structure, and the prolysin exhibits a tight β-sheet conformation, resulting in extremely low natural binding between the two. Even with infrared and dry heating processes, it was difficult to form a large amount of stable covalent complex, leading to a much lower content of effective emulsifying components compared to the distiller's grains group.

[0109] In summary, the emulsion prepared by the arabinoxylan-sorghum prolysin complex disclosed herein has excellent thermal stability and is adaptable to multiple pH environments, which can meet the application needs of multiple scenarios in the food and cosmetic fields. In the food field, it can be used for: (1) High-temperature processed foods: Used in milk beverages and plant protein beverages, after pasteurization (72~85℃) or ultra-high temperature sterilization (135~150℃), it can still maintain a uniform emulsion and avoid stratification and precipitation; (2) Acidic foods: Added to fruit-flavored yogurt (pH 3.5~4.5) and citric acid beverages (pH 3~4), it can stabilize the water-oil system, prevent the precipitation of flavor substances, and extend the shelf life; (3) Baked foods: Used as fillings for cakes and breads, it does not destroy the emulsion structure under high baking temperature, and the finished product has a delicate taste and is not prone to oiliness; (4) Seasoning sauces: Used to make salad dressing (neutral to slightly acidic) and spicy hot pot base (weakly alkaline), adaptable to the pH environment of different flavored sauces, and does not stratify after standing, with better spreadability. In the cosmetics field, it can be used in: (1) High-temperature stable skin care products: used in lotions and creams (neutral to weakly acidic), maintaining a uniform texture and preventing water-oil separation in the high-temperature environment of summer storage or transportation; (2) Acidic skin care products: added to fruit acid exfoliating lotion (pH 3~4) and vitamin C essence lotion (pH 3.5~5) to stabilize active ingredients and oil system and prevent product deterioration; (3) Alkaline cleansing products: used in makeup remover oil and facial cleanser (pH 8~10), maintaining emulsification in alkaline environment, easy to rinse and without residue during cleansing; (4) Sunscreen products: used in sunscreen lotion (pH 5.5~7), not destroying the emulsification structure after high temperature exposure to sunlight, ensuring uniform distribution of sunscreen ingredients and improving the stability of sunscreen effect.

[0110] The disclosed complex emulsion exhibits superior thermal stability and pH adaptability, overcoming the limitations imposed by traditional natural emulsifiers in various applications. In the food industry, it can adapt to high-temperature processing and diverse flavor systems without the need for additional stabilizers. In the cosmetics industry, it is compatible with various formulation pH levels and, as a naturally derived ingredient, aligns with market demands for health and safety.

[0111] 3. The amino acid composition of the arabinoxylan-sorghum prolysin complexes prepared in Example 1 and Comparative Example 1 was tested. The method was carried out in accordance with the national standard GB 5009.124-2016 "Determination of Amino Acids in Food", as follows:

[0112] Weigh 1 g of sample into a hydrolysis tube, add 15 mL of 6 mol / L hydrochloric acid solution, and then add 3 drops of phenol. Freeze the hydrolysis tube for 3 min, evacuate it, then purge it with nitrogen, seal it, and place it in a 110℃ hydrolysis furnace for 22 h. After cooling to room temperature, transfer the hydrolysate to a 50 mL volumetric flask and dilute to volume with distilled water. Accurately pipette 1 mL of the filtrate into a 15 mL test tube, dry it under reduced pressure, add 1 mL of pH 2.2 citrate buffer solution, shake well, filter through a 0.22 μm filter membrane, transfer to the instrument's sample vial, and analyze using an automated amino acid analyzer. The results are as follows: Figure 5 As shown. Figure 5 The results show that, in the basic amino acid category, the Arg and Lys contents of Example 1 are significantly higher than those of Comparative Example 1, and the His content also has a certain advantage. Basic amino acids are positively charged and can be adsorbed onto the oil droplet interface via electrostatic interactions during emulsification, making them one of the core contributors to the interfacial activity of the complex. The high basic amino acid content of Example 1 directly supports its superior emulsification stability. In the acidic amino acid category, the Asp and Glu contents of Example 1 are much higher than those of Comparative Example 1. Acidic amino acids are negatively charged and work synergistically with basic amino acids to form an electrostatic repulsion layer at the oil droplet interface, inhibiting oil droplet aggregation. The high acidic amino acid content of Example 1 further enhances the dispersion stability of the emulsion. Among aliphatic and aromatic amino acids, Example 1 shows higher levels of aliphatic amino acids such as Ala, Leu, Val, and Ile, with Met and Phe also being advantageous. The hydrophobic side chains of aliphatic amino acids can insert into the oil phase, while the benzene ring structure of aromatic amino acids enhances interfacial adsorption capacity. Together, they improve the anchoring effect of the complex at the oil-water interface, making it more difficult for oil droplets to aggregate. Among polar flexible and neutral polar amino acids, Example 1 shows higher levels of Gly, Ser, and Thr. The polar groups of these amino acids can form hydrogen bonds with the aqueous phase, enhancing the hydrophilicity of the complex. At the same time, the flexible structure makes the complex easier to spread at the interface, further optimizing the emulsification effect.

[0113] In summary, the infrared irradiation treatment used in Example 1 can effectively promote the extraction of sorghum prolysin.

[0114] 4. The microstructure of the arabinoxylan-sorghum prolysin complexes prepared in Examples 1-4 and Comparative Examples 1-3 was observed using a scanning electron microscope at 10,000x magnification. The results are as follows: Figure 6 As shown. Figure 6The results show that the arabinoxylan-sorghum prolysin complexes prepared in Examples 1-4 have smoother surfaces, more ordered structural arrangements, and significantly fewer rough prolysin particles. This indicates that the dry heating coupling method used in the examples can effectively promote the binding of arabinoxylan and sorghum prolysin, thereby forming a more stable composite structure.

[0115] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0116] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0117] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for preparing a distillers' grains arabinoxylan-sorghum prolysin complex, characterized in that, Includes the following steps: S1: Dry and crush the lees of baijiu (Chinese liquor) to obtain the raw material; S2: The raw materials are subjected to degreasing and destarching treatment; S3: The material after destarching in step S2 is subjected to infrared irradiation for 30-60 min at a pH of 10.5-12 and a temperature of 50-70℃ to obtain a suspension. S4: Heat the suspension to 80-90°C in a water bath, stir, mechanically shear and centrifuge, and take the first supernatant; adjust the pH of the first supernatant to 3.5-4.0, let it stand, centrifuge and collect the second supernatant; precipitate the second supernatant with alcohol and dry it to obtain the extract; S5: The extract is subjected to a coupling reaction at 55~70℃ and 60~70% humidity to obtain the arabinoxylan-sorghum prolysin complex.

2. The preparation method according to claim 1, characterized in that, In step S1, the drying temperature is 50~60℃.

3. The preparation method according to claim 1, characterized in that, In step S2, the degreasing includes the following steps: mixing the raw material and an organic solvent, vacuum filtering, and drying at 45-50°C for 6-10 h; the mass-to-volume ratio of the raw material and the organic solvent is 0.1-0.167 g / mL; the organic solvent is selected from at least one of n-hexane, petroleum ether, and ethyl acetate; The destarch removal process includes the following steps: adding the degreased material to boiling water, and enzymatically hydrolyzing it with α-amylase in a water bath at 80-90°C for 25-40 minutes to obtain a suspension; centrifuging the suspension, collecting the precipitate, and washing it; The α-amylase accounts for 0.3-0.75% of the volume of the boiling water; the centrifugation speed is 4500-6000 r / min, and the time is 10-20 min.

4. The preparation method according to claim 1, characterized in that, In step S3, the destarched material is added to water, the pH of the solution is adjusted to 10.5-12 with an alkaline solution, and the solution is heated to 50-70°C; the mass concentration of the alkaline solution is 35-55%, and the alkaline solution is selected from any one of sodium hydroxide, calcium hydroxide, and potassium hydroxide; The electric power during infrared irradiation is 300~400 W, and the wavelength is 3~10 μm.

5. The preparation method according to claim 1, characterized in that, In step S4, the mixture is stirred at 500-700 r / min for 20-40 min; mechanically sheared at 10000-12000 r / min for 40-60 min; and centrifuged at 4500-6000 r / min for 10-20 min, and the first supernatant is collected. In step S4, the pH of the first supernatant is adjusted to 3.5-4.0 with 10-12 mol / L hydrochloric acid, allowed to stand for 8-15 min, and then centrifuged at 4500-6000 r / min for 25-40 min before collecting the second supernatant.

6. The preparation method according to claim 5, characterized in that, In step S4, during alcohol precipitation, an alcohol reagent is added, mixed, allowed to stand, and then vacuum filtered to obtain a precipitate. The precipitate is then added to the alcohol reagent and stirred for 5-10 minutes, repeated twice. The final precipitate is dried to obtain the extract. When performing alcohol precipitation, the volume of the alcohol reagent added is 2 to 4 times the volume of the second supernatant; the mixing speed is 200 to 300 r / min, the time is 10 to 15 min; and the standing time is 10 to 12 h. The alcohol reagents include either anhydrous ethanol or isopropanol.

7. The preparation method according to claim 1, characterized in that, The coupling reaction in step S5 takes 12 to 24 hours.

8. The arabinoxylan-sorghum prolysin complex prepared by the method according to any one of claims 1 to 7, characterized in that, In the aforementioned arabinoxylan-sorghum prolysin complex, arabinoxylan and sorghum prolysin are linked by electrostatic interactions and covalent bonds.

9. An emulsifier, characterized in that, The emulsifier includes the arabinoxylan-sorghum prolysin complex of claim 8.

10. The application of the emulsifier according to claim 9 in the food and cosmetic fields.

Images