Highly digestion-resistant highland barley starch-beta-glucan complex and processing method thereof

Abstract

This invention belongs to the field of food processing technology, specifically relating to a barley starch-β-glucan complex with high digestibility and its processing method. The method includes the following steps: feeding barley starch and β-glucan solution sequentially into a twin-screw extruder to obtain a mixture; co-extruding the mixture in the twin-screw extruder under conditions of a moisture content of 50%~60% by mass and an extrusion temperature of 70℃~110℃ to obtain the complex; drying, pulverizing, and sieving the complex to obtain the barley starch-β-glucan complex. The beneficial effects of this invention are: the barley starch-β-glucan complex obtained by this processing method has good thermal stability, a dense gel network structure, good water solubility, and good digestibility (resistant starch content can reach over 23%). This invention is simple to operate, the process parameters are easy to control, the production cost is low, and the process is simple and efficient, providing core technical support for the development of slow-digesting barley starch-based functional foods.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a barley starch-β-glucan complex with high digestibility and its processing method. Background Technology

[0002] Highland barley is a specialty grain of the Qinghai-Tibet Plateau region in my country, rich in starch and β-glucan. β-glucan, a natural non-starch polysaccharide, possesses various physiological functions, including lowering blood sugar and blood lipids. Studies have shown that starch and β-glucan, through physical encapsulation, hydrogen bonding, and gel networks, can synergistically delay the release and absorption of glucose, which is of great significance for developing functional foods with a low glycemic index (GI).

[0003] Currently, researchers generally employ physical, chemical, or enzymatic modification techniques to improve the digestibility of starch-based foods. For example, studies have explored methods such as wet heat treatment and pressurization to modify starch. However, traditional modification techniques often suffer from long processing times, high energy consumption, and degradation of active ingredients, and are difficult to scale up for continuous production. Later, extrusion technology was applied to starch modification, utilizing its high temperature, high pressure, and high shear force thermomechanical effects to alter the functional properties of starch. For instance, Chinese patent CN118985828A discloses a slow-digestible whole barley noodle, which first modifies barley starch using screw extrusion at 125°C, then mixes it with a β-glucan solution to form noodles. However, this process is a two-step method and does not reveal the synergistic regulatory effect of extrusion moisture and temperature. Chinese patent CN109123412A discloses a high-β-glucan whole barley flour extruded rice, with a moisture content of only 24-28%, classifying it as a low-to-medium moisture extrusion method, and focusing on improving texture rather than specifically regulating digestive resistance. Chinese patent CN111393540A only relates to the extraction and purification of β-glucan, and does not involve extrusion processing.

[0004] Existing research primarily focuses on the modification effects of extrusion processes on single starches or polysaccharides. However, systematic research and clear technical solutions are lacking regarding how different extrusion temperatures and moisture levels synergistically regulate the molecular complexation behavior, multi-scale structural evolution, and intrinsic relationship with final digestibility during high-moisture extrusion. Traditional processing methods often struggle to precisely control the structure formation of the complex, leading to unstable improvements in digestibility. Therefore, developing a processing method that can effectively regulate the structure of the barley starch-β-glucan complex and enhance its digestibility has significant application value. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a barley starch-β-glucan complex with strong thermal stability, dense gel network structure, high water solubility and high digestibility, and a processing method thereof.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A processing method for a barley starch-β-glucan complex with high digestibility is provided, comprising the following steps: The highland barley starch and β-glucan solution were fed into a twin-screw extruder in sequence to obtain a mixture. The mixture is co-extruded in a twin-screw extruder at a moisture content of 50% to 60% by mass and an extrusion temperature of 70°C to 110°C to obtain a composite. The complex was dried, pulverized, and sieved to obtain the barley starch-β-glucan complex.

[0007] The beneficial effects of this invention are as follows: The processing method of this invention, through precise control of the extrusion temperature, promotes the transformation of the barley starch crystal structure from type A to type V, forming a single helix structure with up to 4.09% and a tight hydrogen bond network, significantly improving the thermal stability, gel network density, and digestibility of the complex. Simultaneously, by controlling the extrusion moisture content, the competition between starch chain degradation and ordered recombination is intervened, promoting amylose rearrangement and V-shaped crystal formation, increasing the resistant starch content to over 23%. During this process, β-glucan and moisture work synergistically, using hydrogen bonds at the molecular level to inhibit excessive starch chain breakage and induce single helix structure enrichment, and enhancing the density of the gel network at the macroscopic level, forming a physical barrier. Furthermore, the one-step co-extrusion process of this invention is simpler, more efficient, and continuous than the existing two-step method, and avoids excessive degradation caused by high temperature (125℃), thus achieving the green preparation of a barley starch-β-glucan complex with strong thermal stability, a dense gel network, high water solubility, and excellent slow digestibility.

[0008] Furthermore, in the above-mentioned processing method for the high digestibility barley starch-β-glucan complex, the moisture content of the mixture is 55% by mass, and the extrusion temperature is 90°C.

[0009] As described above, this optimized parameter achieves a synergistic effect of moderate starch depolymerization and ordered rearrangement. Scanning electron microscopy (SEM) results show that the complex prepared under these conditions forms a dense and continuous gel network structure. This highly dense network structure provides a more effective physical encapsulation barrier for starch granules, thereby significantly hindering the penetration and action of digestive enzymes. Experimental results show that this optimized scheme achieves a resistant starch content of over 23.25%, with excellent thermal stability and water solubility. The discovery of this nonlinear optimal parameter overturns the traditional understanding that higher temperatures and higher moisture content lead to faster digestion, embodying the core of this invention.

[0010] Furthermore, in the above-mentioned processing method for the high digestibility barley starch-β-glucan complex, the twin-screw extruder is provided with eight barrels in sequence along the material conveying direction, wherein the temperatures of the first to third barrels are 40°C, 50°C, and 60°C, respectively; the temperatures of the fourth to sixth barrels are the extrusion temperatures; and the temperatures of the seventh to eighth barrels are 60°C and 50°C, respectively.

[0011] As described above, gradient preheating gradually activates barley starch without causing violent boiling; a sufficiently long isothermal reaction zone ensures the full transformation of the crystal structure from type A to type V and the enrichment of the single helical structure; gradient cooling ensures the orderly shaping of the formed gel network and hydrogen bonds, preventing structural breakage due to excessive temperature difference during discharge, thereby obtaining a complex with strong thermal stability and dense structure.

[0012] Furthermore, in the above-mentioned processing method for the barley starch-β-glucan complex with high digestibility, the β-glucan solution is added at the port of the third barrel, and the barley starch is added at the port of the first barrel.

[0013] As described above, barley starch is first preheated independently in the first and second barrels, where the granules begin to absorb water and swell, and the crystal structure loosens. It is then mixed with the β-glucan solution in the third barrel. This process prevents β-glucan from entering the high-temperature zone too early, which could lead to degradation or excessive water absorption. Simultaneously, it ensures that the starch, in a semi-activated state, fully bonds with the hydroxyl groups of β-glucan, thereby maximizing the synergistic effect of both.

[0014] Furthermore, in the above-mentioned processing method for the barley starch-β-glucan complex with high digestibility, the solute mass concentration of the β-glucan solution is 2%; and the average molecular weight of the β-glucan is 47068 Da.

[0015] As described above, this specific molecular weight of β-glucan is rich in hydroxyl groups, which can form the most stable hydrogen bond network with starch, inhibit excessive shearing and induce the formation of a single helix structure.

[0016] Furthermore, in the above-mentioned processing method for the highly digestible barley starch-β-glucan complex, the β-glucan solution is prepared by the following steps: whole barley flour and water are mixed at a material-to-liquid ratio of 1:10 g / mL and incubated at 80°C for 2 hours; after cooling, the slurry is centrifuged at 4000 rpm for 30 minutes, the supernatant is collected, concentrated under reduced pressure, and ethanol is added for precipitation; the precipitate is recovered by centrifugation at 4000 rpm for 20 minutes, washed with ethanol, and dried under vacuum to obtain β-glucan, which is then redissolved in water to prepare a β-glucan solution with a mass concentration of 2%.

[0017] As described above, the extraction method employs a water extraction and alcohol precipitation process, which does not introduce exogenous enzyme preparations or organic solvent residues. The operation is mild and cost-effective. The extracted β-glucan retains its natural molecular weight distribution (average molecular weight approximately 47068 Da) and abundant hydroxyl structures, enabling it to form a stable hydrogen bond network with barley starch during extrusion. This method is simpler and more suitable for industrial production.

[0018] Furthermore, in the above-mentioned processing method for the barley starch-β-glucan complex with high digestibility, the dry basis purity of the barley starch is 93%.

[0019] As described above, high-purity starch ensures uniform depolymerization of starch molecular chains during extrusion, avoiding interference from impurities in the orderly rearrangement of the complex.

[0020] Furthermore, in the above-mentioned processing method for the barley starch-β-glucan complex with high digestibility, the feeding rate of the twin-screw extruder is 7.5 g / min, and the screw speed is 180 rpm.

[0021] As described above, the parameter combination ensures sufficient residence time for the material within the barrel (to complete depolymerization and rearrangement) while providing appropriate shear force. Too low a feed rate leads to decreased production efficiency, while too high a rate results in insufficient residence time; excessively high screw speeds cause excessive shear degradation, while too slow speeds lead to uneven mixing. This optimal value ensures the material receives the most suitable mechanical energy input under optimal temperature and moisture conditions, synergistically achieving appropriate depolymerization.

[0022] Another technical solution of the present invention is: to provide a high-digestibility barley starch-β-glucan complex prepared by a processing method of the above-mentioned high-digestibility barley starch-β-glucan complex.

[0023] The obtained highland barley starch-β-glucan complex possesses unique structural characteristics and properties: its crystal structure transforms from type A to type V, the content of single helix structure can reach over 4.09%, and the content of resistant starch can reach over 23%. These structural characteristics endow the complex with excellent thermal stability, high water solubility, and slow digestibility, making it suitable as a base material for low glycemic index (GI) functional foods, significantly different from simple mixing or low-moisture extrusion products in existing technologies. Attached Figure Description

[0024] Figure 1 This is a comparative schematic diagram showing the thermal stability of embodiments and comparative examples of the present invention. Figure 2 The images shown are scanning electron microscope (SEM) images of samples obtained from specific embodiments and comparative examples of this invention.

[0025] Figure 3This is a schematic diagram comparing the gel properties of samples obtained from specific embodiments and comparative examples of the present invention. Figure 4 This is a schematic diagram comparing the water solubility of samples obtained from specific embodiments and comparative examples of the present invention; Figure 5 This is a schematic diagram comparing the anti-digestion properties of samples obtained from specific embodiments and comparative examples of the present invention. Detailed Implementation To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0026] Existing technologies often focus on starch modification, using physical, chemical, or enzymatic methods to increase resistant starch content or improve digestibility. However, they generally overlook the synergistic regulatory role of two key parameters during extrusion processing (extrusion temperature and extrusion moisture) on the molecular interactions between starch and β-glucan. In particular, they fail to recognize the existence of an optimal processing parameter within which thermomechanical action can achieve a synergistic effect of "moderate depolymerization and ordered rearrangement," thereby enhancing functional properties. Traditional views often hold that higher extrusion temperatures and higher moisture content lead to more thorough starch degradation and faster digestion. However, this invention, through in-depth research, reveals for the first time that extrusion temperature and extrusion moisture have non-linear regulatory characteristics on the structural evolution and digestibility of starch-β-glucan complexes, exhibiting an optimal temperature range (approximately 90°C) and an optimal moisture range (approximately 55%). Under these conditions, a barley starch-β-glucan complex with strong thermal stability, a dense gel network structure, high water solubility, and slow digestibility can be prepared.

[0027] This invention reveals that extrusion temperature, by regulating the degree of depolymerization and conformational rearrangement of starch molecular chains, dominates the formation of the multi-scale structure of the complex. When the extrusion temperature is too low (e.g., 70°C), the thermomechanical action is insufficient to fully disrupt the crystalline structure of starch granules, limiting the intermolecular interactions between starch and β-glucan. This results in insufficient structural reorganization of the complex, failing to form a dense gel network, and leading to unsatisfactory thermal stability and water solubility. When the extrusion temperature is too high (e.g., 110°C), excessive thermomechanical action causes excessive breakage and degradation of starch molecular chains, dissociating the single-helix structure and weakening the density of the gel network, thus reducing thermal stability. Only at a suitable extrusion temperature (e.g., 90°C) can moderate heat and shear force induce controlled depolymerization of starch molecular chains, simultaneously inducing the partially molten double-helix structure to reconstruct a thermodynamically more stable single-helix structure, forming the tightest hydrogen bond network, thereby enabling the complex to achieve a dense gel network structure and excellent thermal stability.

[0028] Furthermore, this invention also discovered that the moisture content plays a crucial role in the formation of the starch-β-glucan complex. Moisture is not only a plasticizer for starch gelatinization but also an important medium for regulating the flowability of polysaccharide chains and intermolecular interactions. When the moisture content is too low (e.g., 50%), the material is insufficiently plasticized, starch granules fail to fully disintegrate, and the exposed hydrophilic groups are limited, resulting in insufficient water solubility of the complex. When the moisture content is too high (e.g., 60%), excessive moisture buffers shear forces, weakens the strength of hydrogen bond interactions, and leads to a decrease in the stability of the ordered structure. Only at a suitable moisture content (e.g., 55%) is the material viscosity moderate, shear and heat transfer efficiency highest, starch molecular chains undergo moderate breakage, exposing more hydrophilic groups and significantly improving the water solubility of the complex. Simultaneously, moderate degradation provides sufficient short-chain fragments for molecular rearrangement, inducing the formation of high-content V-shaped crystal structures and single-helix structures, allowing ordered rearrangement to dominate in the competition, ultimately endowing the complex with excellent slow-digestion properties.

[0029] The β-glucan introduced in this invention exhibits a synergistic regulatory effect with extrusion temperature and moisture content. At the molecular level, β-glucan forms a hydrogen bond network with starch molecules through its abundant hydroxyl groups. On the one hand, this buffers local shear stress and inhibits excessive chain breakage. On the other hand, β-glucan competes with amylose for hydrogen bond formation, inhibiting the stacking of amylopectin double helixes, while simultaneously inducing and stabilizing single-helix conformations, thereby promoting V-shaped crystal formation and further enhancing the thermal stability of the complex. At the macroscopic level, β-glucan enhances the density of the gel network, constructing a physical barrier against enzymatic hydrolysis. Simultaneously, its steric hindrance effect hinders enzyme-substrate recognition at the molecular level, synergistically improving the slow digestibility of the complex. Furthermore, β-glucan itself has good hydrophilicity, and its introduction further promotes the high water solubility of the complex. This multi-scale synergistic effect from the molecular to the macroscopic level enables the successful preparation of a barley starch-β-glucan complex with strong thermal stability, a dense gel network structure, high water solubility, and excellent slow digestibility under optimal temperature and moisture conditions.

[0030] Therefore, this invention utilizes high-moisture extrusion technology with precise control of extrusion temperature and moisture to screen out the optimal processing conditions for barley starch-β-glucan complexes that exhibit strong thermal stability, dense gel network structure, high water solubility, and slow digestibility.

[0031] The following are some preferred embodiments and comparative examples to help those skilled in the art better understand the technical content of the present invention and the technical contributions made by the present invention compared with the prior art: Preparation of raw materials for this invention: The extraction of barley starch was carried out as follows: After selection and impurity removal, barley grains were milled in a rice milling machine (milling rate: 20%), and then soaked in a 0.5% anhydrous sodium sulfite solution at a material-to-liquid ratio of 5:1 v / w. The soaking was carried out at 4℃ for 60 h, with stirring every 12 h during the soaking period. After soaking, the soaking solution was discarded, and the softened barley grains were repeatedly rinsed with distilled water until no soaking solution remained on the surface. The washed grains were added to a pulping machine with an appropriate amount of distilled water for pulping and crushing. The pulp was then passed through an 80-mesh nylon filter cloth to remove coarse residue. The filtrate was collected and allowed to stand at 25℃ for 3 h to allow the starch to settle naturally. The suspended liquid was centrifuged at 3000 r / min for 20 min, the supernatant was discarded, and the pale yellow protein layer and colored impurities on the surface of the starch layer were carefully scraped off, leaving only the pure white starch precipitate at the bottom. Distilled water was added to the precipitate for washing again, followed by centrifugation at 3000 r / min for 20 min. This washing process was repeated three times. The precipitate was then washed with anhydrous ethanol three times to further dehydrate and remove water-soluble impurities. The purified wet starch was transferred to a petri dish and allowed to air dry at room temperature for 24 h. The dried starch was then sieved through a 100-mesh standard sieve, sealed, and stored in a desiccator at room temperature for later use.

[0032] The extraction of β-glucan from highland barley was as follows: Highland barley grains were crushed and passed through a 60-mesh sieve to obtain whole highland barley flour. The whole highland barley flour was mixed with distilled water at a material-to-liquid ratio of 1:10 (w / v, g / mL), and placed in a constant temperature water bath. The mixture was incubated at 80℃ for 2 hours, with low-speed stirring to ensure thorough extraction. After extraction, the mixture was cooled to room temperature, and the mixture was centrifuged at 4000 r / min for 30 min, collecting the supernatant. The collected supernatant was transferred to a rotary evaporator, and the concentration temperature was set to 55℃, vacuum degree to -0.08 MPa, and rotation speed to 80 r / min. The mixture was concentrated under reduced pressure to 1 / 5 of its original volume to obtain a concentrated β-glucan solution. Four times the volume of anhydrous ethanol was slowly added to the concentrated solution while stirring, and the mixture was allowed to stand for 12 hours to allow the β-glucan to fully extract. The dextran was fully precipitated. The alcohol precipitation system was centrifuged at 4000 r / min for 20 min, and the polysaccharide precipitate was collected. The precipitate was washed twice with anhydrous ethanol to remove monosaccharides and small molecule impurities. The precipitate was placed in a vacuum drying oven and dried at 50℃ to constant weight to obtain barley β-glucan. Dextran should be stored in a sealed container at 4°C for later use.

[0033] Example 1 A processing method for a barley starch-β-glucan complex with high digestibility includes the following steps: Step 1: The barley starch raw material is metered and added to the first barrel port using a volumetric twin-screw feeder. The twin-screw extruder has eight barrels arranged sequentially along the material conveying direction; Step 2: Accurately weigh the dry powder of highland barley β-glucan, add distilled water to prepare a 2% (w / v) β-glucan aqueous solution, stir for 30 min until the β-glucan is completely dissolved, let it stand at room temperature of 25℃ for 15 min to remove the air bubbles in the solution, and obtain the β-glucan solution for later use.

[0034] The β-glucan has an average molecular weight of 47068 Da, a neutral sugar content of 85.42 g / 100 g, and a protein content of 1.09 g / 100 g. Its monosaccharide composition is mainly glucose (with small amounts of arabinose and xylose), with a molar ratio of 9.8:0.1:0.1.

[0035] The liquid (β-glucan solution) is delivered to the third barrel port via a digital peristaltic pump.

[0036] Step 3: Set the feed rate of the modular twin-screw extruder to 7.5 g / min and the screw speed to 180 r / min.

[0037] The temperatures of the eight barrels were set as follows: 40℃, 50℃, 60℃, 70℃, 70℃, 70℃, 60℃, and 50℃. By adjusting the solid-liquid feed rate, a final sample with a moisture content of 50% was obtained. After the extrusion system had been running stably for 5 minutes, the starch extrudate was collected from the collection port. The freshly prepared extrudate was placed at 25℃ for 15 minutes.

[0038] Step 4: Place the extrudate obtained in Step 3 in an oven and dry at 40°C for 24 hours until the moisture content is ≤10%. Grind the powder using a Rongshida mill and pass it through a 120-mesh sieve to obtain barley starch-β-glucan complex powder. Pack the powder into sealed bags and store in a dry environment.

[0039] Example 2 The rest is the same as in Example 1, except that in step 3, the extrusion temperature of the fourth to sixth barrels is set to 90°C.

[0040] Example 3 The rest is the same as in Example 1, except that in step 3, the extrusion temperature of the fourth to sixth barrels is set to 110°C.

[0041] Example 4 The rest is the same as in Example 1, except that in step 3, the moisture content of the final sample in the extruder is set to 55%, and the extrusion temperature of the fourth to sixth barrels is 90°C.

[0042] Example 5 The rest is the same as in Example 1, except that in step 3, the moisture content of the final sample from the extruder is set to 60%, and the extrusion temperature of the fourth to sixth barrels is 90°C.

[0043] Comparative Example 1 The rest is the same as in Example 1, except that step 2 is omitted, β-glucan solution is not used, and barley starch is simply extruded.

[0044] Comparative Example 2 The rest is the same as in Example 2, except that step 2 is omitted, β-glucan solution is not used, and barley starch is simply extruded.

[0045] Comparative Example 3 The rest is the same as in Example 3, except that step 2 is omitted, β-glucan solution is not used, and barley starch is simply extruded.

[0046] Comparative Example 4 The rest is the same as in Example 4, except that step 2 is omitted, β-glucan solution is not used, and barley starch is simply extruded.

[0047] Comparative Example 5 The rest is the same as in Example 5, except that step 2 is omitted, β-glucan solution is not used, and barley starch is simply extruded.

[0048] Comparative Example 6 The rest is the same as in Example 1, except that steps 1-3 are omitted, and raw barley starch is ground (extracted starch without any treatment) and sieved.

[0049] 1. Testing Method Methods for determining thermal stability: Samples from Examples 1-5 and Comparative Examples 1-6 were mixed with distilled water at a ratio of 1:3 (w / w), sealed in an aluminum box, and left at room temperature for 24 hours to allow for moisture equilibration before measurement. An empty, sealed aluminum box was used as a blank control. The measurement conditions were set to increase the temperature from 30°C to 100°C at a rate of 10°C / min. The initial temperature was recorded. T 0), Peak temperature ( T p ), termination temperature ( T c ) and enthalpy change of melting (Δ H ).

[0050] Scanning electron microscopy (SEM) measurement methods: The morphological characteristics of the samples in Examples 1-5 and Comparative Examples 1-6 were examined using a scanning electron microscope (Zeiss Sigma 360, Germany). In short, approximately 10 mg of sample was attached to a conductive adhesive, sputtered with gold, and images were acquired at 1000x and 4000x magnification.

[0051] Methods for determining gel properties: After gelatinization, 6% of the sample solutions from Examples 1-5 and Comparative Examples 1-6 were placed on a dynamic rheometer (MCR301, Anton Paar, Austria). Measurements were performed at 25°C. Dynamic viscoelasticity was determined in strain-controlled mode with a strain of 1% and an angular frequency range of 0.1 to 10 rad / s. Steady-state shear viscosity was measured from 0.1 to 10 s⁻¹. - ¹The shear rate is measured by scanning.

[0052] Methods for determining hydration characteristics: Weigh 0.5 g of the samples from Examples 1-5 and Comparative Examples 1-6 (dry basis, denoted as W0) and place them into a pre-weighed centrifuge tube (W1). Add 15 mL of purified water and incubate the mixture in a 90°C water bath for 30 min. After incubation, centrifuge the tube at 4000 rpm for 30 min. Carefully transfer the supernatant to a pre-weighed aluminum pan (W2) and dry it in a 105°C oven to constant weight (W3). Weigh the centrifuge tube containing the precipitate again (W4). Then calculate the water absorption rate, water solubility index, and swelling force using the following formulas: Methods for determining resistance to digestion: 70 mg of each sample from Examples 1-5 and Comparative Examples 1-6 was dispersed in 2 mL of distilled water and continuously stirred at 200 rpm in a 37°C water bath. Then, 1 mL of pepsin solution (1 mg / mL in 0.02 M hydrochloric acid) was added. After incubation for 30 min, a mixture containing 1 mL of pancreatic enzyme solution and 5 mL of 0.2 M acetate buffer (pH 6.0) was added. The pancreatic enzyme solution was prepared by dissolving 20 mg of pancreatic enzyme and 86 µL of amylase in 10 mL of the same acetate buffer. Aliquots were collected at specified time intervals (0, 5, 10, 15, 20, 30, 45, 60, 90, 120, 150, 180, 210, 240, and 300 min), and glucose concentration was measured using the GOPOD assay. To further analyze the digestion characteristics of the samples at different extrusion temperatures, a logarithmic slope (LOS) plot combined with parallel and continuous digestion kinetics (CPS) models was used. Initially, the starch digestion curve was fitted using a LOS plot derived from the following formula: in C t , C 0 and C ∞ They are in t The proportions of starch hydrolyzed at min, 0 min, and the end of the reaction. k It is the starch digestion rate coefficient.

[0053] LOS plots identify the number of starch components with different digestion rate constants. When multiple starch components are present in the digestive tract, the CPS method is used to distinguish their respective digestion curves. The CPS kinetic model is expressed by the following equation: in C 1∞ and C 2∞ This represents the maximum digestible amount of the two starches. k 1 and k 2 represents their respective digestion rate constants. t 2start This is the time when slow digestion begins. These parameters ( k 1. k 2. t 2start , C 1∞ , C 2∞ The value was obtained through nonlinear least squares (NLLS) fitting in Microsoft Excel. Resistant starch content (RS) = 1 - ( C 0+C 1∞ + C 2∞ ). 2. Data Analysis Each experiment was repeated three times, and results are expressed as mean ± standard deviation. SPSS Statistics 22.0 and Excel software were used to analyze the experimental data. Duncan's test was used to compare the significance of different data points, with a detection limit of 0.05. P <0.05 indicates a significant difference.

[0054] like Figure 1 Δ in Example 4 T p - T o The temperature was 3.9 °C, while the ΔC of Examples 1-3 and Comparative Examples 1-6 was... T p - T o The temperatures were 5.8 °C, 7.6 °C, 10.2 °C and 10.2 °C, 6.6 °C, 4.0 °C, 6.9 °C, 7.3 °C, 4.3 °C, respectively. like Figure 4 The water solubility index of Example 4 was 21.2 g / 100 g, while the water solubility indices of Examples 1-3 and Comparative Examples 1-6 were 23.5 g / 100 g, 20.1 g / 100 g, 21.4 g / 100 g and 22.9 g / 100 g, 16.4 g / 100 g, 20.5 g / 100 g, 17.3 g / 100 g, 11.1 g / 100 g, and 6.6 g / 100 g, respectively. like Figure 5 The resistant starch content in Example 4 was 23.25%, while the resistant starch contents in Examples 1-3 and Comparative Examples 1-6 were 10.57%, 17.01%, 6.67% and 8.59%, 16.36%, 5.70%, 20.00%, 17.90%, 17.19%, respectively. from Figures 1 to 5 It can be seen that the barley starch-β-glucan complex prepared in Example 4 (90℃, 55% moisture) exhibits significantly better thermal stability, gel network structure, water solubility, and anti-digestion properties than other examples and comparative examples. The results from each example and comparative example demonstrate the synergistic effect and interaction between the various processes in this invention; omitting any one of them would prevent the preparation of barley starch-β-glucan powder with strong thermal stability, a dense gel network structure, high water solubility, and excellent slow digestion properties.

[0055] The method described in this invention achieves good thermal stability, a dense gel network structure, good water solubility, and resistance to digestion of the barley starch-β-glucan complex (resistant starch content can reach over 23%). Rheological test results show that Example 4 (90℃ / 55% moisture) has the lowest overall loss modulus, while Examples 1-3 and Comparative Examples 1-6 all have significantly higher loss moduli.

[0056] 3. Results Analysis: The measurement results are as follows Figure 1-5 As shown. The results indicate that the barley starch-β-glucan complex prepared in Example 4 (90℃, 55% moisture) exhibits significantly better overall performance than other examples and comparative examples in terms of thermal stability, gel network regularity and density (scanning electron microscopy shows a continuous and uniform gel network), gel properties (the system exhibits a gel state dominated by elasticity, with the lowest loss modulus), water solubility (water solubility index reaches 21.2), and digestibility (resistant starch content reaches 23%).

[0057] In comparison, the performance of Example 2 (90°C, 50% moisture) and Example 5 (90°C, 60% moisture) was inferior to that of Example 4, proving that 55% moisture is the optimal value; The performance of Example 1 (70°C) and Example 3 (110°C) was also significantly lower than that of Example 2 (90°C), proving that 90°C is the optimal temperature.

[0058] The performance of Comparative Examples 1-5 (without β-glucan) was significantly lower than that of the corresponding Examples, demonstrating the key synergistic effect of β-glucan; Comparative Example 6 (untreated) showed poor performance in all aspects.

[0059] In summary, the processing method for the highly digestible barley starch-β-glucan complex provided by this invention fully leverages the synergistic advantages between barley starch and β-glucan. By precisely controlling the extrusion temperature (especially 90℃) and extrusion moisture (especially 55%), the method achieves directional design of the complex's multi-scale structure. This processing method significantly improves the complex's thermal stability, gel network density, water solubility, and slow digestibility, promoting the high-value utilization of barley and providing core technical support for the development of functional foods with low glycemic index (GI).

[0060] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A processing method for a barley starch-β-glucan complex with high digestibility, characterized in that, Includes the following steps: The highland barley starch and β-glucan solution were fed into a twin-screw extruder in sequence to obtain a mixture. The mixture is co-extruded in a twin-screw extruder at a moisture content of 50% to 60% by mass and an extrusion temperature of 70°C to 110°C to obtain a composite. The complex was dried, pulverized, and sieved to obtain the barley starch-β-glucan complex.

2. The processing method of the high-digestibility barley starch-β-glucan complex according to claim 1, characterized in that, The mixture has a moisture content of 55% by mass, and the extrusion temperature is 90°C.

3. The processing method of the high-digestibility barley starch-β-glucan complex according to claim 1, characterized in that, The twin-screw extruder has eight barrels arranged sequentially along the material conveying direction. The temperatures of the first to third barrels are 40°C, 50°C, and 60°C, respectively. The temperatures of the fourth to sixth barrels are the extrusion temperatures, and the temperatures of the seventh and eighth barrels are 60°C and 50°C, respectively.

4. The processing method of the high-digestibility barley starch-β-glucan complex according to claim 3, characterized in that, The β-glucan solution is added at the port of the third barrel, and the barley starch is added at the port of the first barrel.

5. The processing method of the high-digestibility barley starch-β-glucan complex according to claim 1, characterized in that, The solute concentration of the β-glucan solution is 2%; the average molecular weight of the β-glucan is 47068 Da.

6. The processing method of the high-digestibility barley starch-β-glucan complex according to claim 5, characterized in that, The β-glucan solution was prepared by the following steps: whole barley flour and water were mixed at a material-to-liquid ratio of 1:10 g / mL and incubated at 80°C for 2 hours; after cooling, the slurry was centrifuged at 4000 rpm for 30 minutes, the supernatant was collected, concentrated under reduced pressure, and ethanol was added for precipitation; the precipitate was recovered by centrifugation at 4000 rpm for 20 minutes, washed with ethanol, and dried under vacuum to obtain β-glucan, which was then redissolved in water to prepare a 2% β-glucan solution.

7. The processing method of the high-digestibility barley starch-β-glucan complex according to claim 1, characterized in that, The dry basis purity of the barley starch is 93%.

8. The processing method of the high-digestibility barley starch-β-glucan complex according to claim 1, characterized in that, The twin-screw extruder has a feed rate of 7.5 g / min and a screw speed of 180 rpm.

9. A barley starch-β-glucan complex with high digestibility prepared by the processing method according to any one of claims 1-8.

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