A method for optimizing extraction process of quercus mongolica nut starch

Abstract

The application discloses a kind of optimization methods of Mongolian oak acorn starch extraction process, belong to the optimization method field of acorn starch extraction process.The application uses acorn starch as raw material, the influence of NaOH mass fraction, solid-liquid ratio, ultrasonic time and ultrasonic power four factors on acorn starch extraction effect is investigated by single factor experiment, and using response surface Box-Behnken analysis method is carried out to the extraction process optimization, and the best extraction condition is determined.According to actual situation adjustment parameter is: sodium hydroxide mass fraction 0.33%, solid-liquid ratio 1:12 g / mL, ultrasonic time 36 min, ultrasonic power 310 W.Under the condition, the average yield of acorn starch is 77.41%, and is similar to theoretical value.The yield of acorn starch prepared under the preparation condition of the application is 77.41%, compared with traditional alkali method, and is increased by 25.98%.The microporous starch prepared from acorn starch under the application has good adsorption performance, and can be widely applied in food, chemical and other fields as adsorbent material.

Description

Technical Field

[0001] This invention belongs to the field of optimization methods for acorn starch extraction processes; specifically, it uses single-factor experiments and response surface methodology, with starch yield as the response value, to optimize the process of extracting Mongolian oak acorn starch using ultrasonic-assisted soaking alkali extraction. Background Technology

[0002] Mongolian oak (Quercus mongolica) is widely distributed and covers a large area, forming a major component of secondary deciduous broad-leaved forests in Inner Mongolia, Heilongjiang, Liaoning, and Jilin provinces. In Heilongjiang province alone, Mongolian oak covers 2.46 million hectares. Mongolian oak acorn resources are abundant, with an annual production exceeding 2 million tons. The nutritional indicators of acorns are similar to those of corn, indicating high nutritional value. Its starch content is as high as 55-70%, slightly lower than rice, making it a high-quality wild starch resource. Mongolian oak acorn starch is a raw material for producing vermicelli, jelly, alcohol, maltose, modified starch, resistant starch, biodegradable biomaterials, and drug carriers. However, the utilization rate of Mongolian oak acorns in China is very low, and acorn starch processing is scattered and fragmented, lacking scale, and mostly producing crude starch. Therefore, there is a shortage of refined Mongolian oak acorn starch. Summary of the Invention

[0003] This invention employs an ultrasound-assisted dilute alkali method to extract starch from Mongolian oak acorns, and uses protease to remove residual protein from the starch. Through single-factor experiments and response surface methodology, the optimal process is explored. This invention develops an efficient and time-saving method for preparing acorn starch, providing experimental evidence and theoretical guidance for the industrialization and application of acorn starch.

[0004] Single-factor experiments and response surface methodology were employed, with starch yield as the response value, to optimize the extraction process of Mongolian oak acorn starch using ultrasound-assisted soaking and alkali extraction. Then, using the extracted acorn starch as raw material, microporous starch was prepared via a gel-freeze method, and its particle structure and properties were determined. The results showed that the highest acorn starch yield was achieved under the following conditions: NaOH mass fraction of 0.33%, material-to-liquid ratio of 1:12 g / mL, ultrasonic time of 36 min, and ultrasonic power of 310 W.

[0005] To solve the above-mentioned technical problems, this invention provides an optimized method for the extraction process of starch from Mongolian oak acorns, which is achieved through the following steps:

[0006] After the acorns were crushed and defatted, they were divided into several portions. The mass fraction of NaOH, the material-to-liquid ratio, the ultrasonic power and the ultrasonic temperature were selected for single-factor determination. The acorns were subjected to ultrasonic alkaline extraction with NaOH solution under different conditions. After protein removal, washing, drying, grinding and sieving, the starch yield was determined.

[0007] The starch samples treated with the above methods were subjected to Placketet-Burman experiments to analyze the significance of the effect of each single factor on starch yield.

[0008] Based on the results of single-factor experiments, and according to the Box-Behnken central composite experiment, a four-factor, three-level experiment was designed with NaOH mass fraction, material-liquid ratio, ultrasonic power and ultrasonic temperature as independent variables and acorn starch yield as the response value. The variance analysis of the response surface quadratic model was obtained to optimize the acorn starch process.

[0009] The interaction between the four factors with starch yield as the response value was analyzed using Design Expert-12 software. The response surface plot of the effect of the interaction between the two factors on the acorn starch yield was obtained. The slope of the response surface reflects the degree of influence of the interaction between the factors on the response value. The larger the slope, the more significant the influence on the response value.

[0010] The optimal conditions for acorn starch extraction were obtained from the response surface 3D image and results, thus completing the optimization.

[0011] Further, the acorns are crushed and passed through an 80-mesh sieve. The resulting acorn powder is mixed with petroleum ether at a mass ratio of 1:10 and stirred for 24 hours for the first degreasing, followed by filtration. Then, the mixture is stirred at a mass ratio of 1:5 for 24 hours for the second degreasing, followed by filtration. Finally, the mixture is dried at 45°C for 1-2 hours to complete the degreasing process.

[0012] To further specify, defatted acorn powder was added to NaOH solution and starch was extracted under ultrasound.

[0013] To further specify, protein removal was performed as follows: the lower precipitate was washed with distilled water, the solution pH was adjusted to 10, alkaline protease (200 U / g) was added, and the solution was enzymatically hydrolyzed in a water bath at 46°C for 145 min, then removed and cooled.

[0014] Further specifying, the washing is performed as follows: centrifuge at 3000 r / min for 15 min, add water to the precipitate at a mass ratio of 1:5, let stand for 4-5 h to separate into layers, discard the supernatant, and repeat three times.

[0015] Further specified, the product must be dried at 45°C for at least 12 hours and then passed through an 80-mesh sieve.

[0016] Further specified, the mass fraction of NaOH solution in the single-factor experiment was selected as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.6%; the material-to-liquid ratio was selected as 1:4, 1:6, 1:8, 1:10, 1:12, 1:14, and 1:16 (unit: g / mL); the ultrasonic power was selected as 200W, 250W, 300W, 350W, 400W, and 450W; and the ultrasonic time was selected as 20min, 25min, 30min, 35min, 40min, and 45min.

[0017] Further defining the parameters, the quadratic multinomial regression equations obtained by fitting A-NaOH mass fraction (%), B-solid-to-material ratio (g / ml), C-ultrasonic time (min), D-ultrasonic power (w), and R-starch yield (%) using Design-Expert software are as follows:

[0018] Y1=0.636742A+0.61875B+0.544092C+0.816017D+0.17245AB+0.042825AC+0.0554AD+0.3638BC+0.14165BD+0.3617CD-1.21972A 2 -1.45408B 2 -1.40757C 2 -1.34268D 2 +77.0277.

[0019] Further, the extraction process was optimized using response surface methodology (Box-Behnken) to determine the optimal extraction conditions: NaOH mass fraction 0.329%, solid-liquid ratio 1:12.57 g / mL, ultrasonic time 36.81 min, and ultrasonic power 314.01 W.

[0020] Further, the parameters were adjusted according to the actual situation as follows: NaOH mass fraction of 0.33%, material-to-liquid ratio of 1:12 g / ml, ultrasonic time of 36 min, and ultrasonic power of 310 W.

[0021] This invention uses Mongolian oak acorn starch as raw material. Single-factor experiments were conducted to investigate the effects of four factors—NaOH mass fraction, solid-liquid ratio, ultrasonic time, and ultrasonic power—on the extraction efficiency of acorn starch. The extraction process was optimized using Box-Behnken response surface methodology, and the optimal extraction conditions were determined as follows: NaOH mass fraction 0.329%, solid-liquid ratio 1:12.57 g / mL, ultrasonic time 36.81 min, and ultrasonic power 314.01 W. The theoretical yield was 77.43%. Based on actual conditions, the parameters were adjusted to: sodium hydroxide mass fraction 0.33%, solid-liquid ratio 1:12 g / mL, ultrasonic time 36 min, and ultrasonic power 310 W. Under these conditions, the average yield of acorn starch was 77.41%, close to the theoretical value. The acorn starch yield obtained under the conditions of this invention is 77.41%, which is 25.98% higher than that of the traditional alkaline method. The microporous starch prepared using the acorn starch under these conditions exhibits excellent adsorption properties and can be widely used as an adsorbent material in the food, chemical, and other fields.

[0022] To further understand the features and technical content of this invention, please refer to the following detailed description and accompanying drawings. However, the accompanying drawings are for reference and illustration only and are not intended to limit the invention. Attached Figure Description

[0023] Figure 1 The effect of sodium hydroxide mass fraction on acorn starch yield;

[0024] Figure 2 The effect of the material-to-liquid ratio on the yield of acorn starch;

[0025] Figure 3 The effect of ultrasonic power on acorn starch yield;

[0026] Figure 4 The effect of ultrasonic time on acorn starch yield;

[0027] Figure 5a This is a response surface plot showing the effect of the interaction between the material-liquid ratio and the mass fraction of NaOH on the yield of acorn starch.

[0028] Figure 5b This is a response surface plot showing the effect of the interaction between ultrasonic time and NaOH mass fraction on the yield of acorn starch.

[0029] Figure 5c This is a response surface plot showing the effect of the interaction between ultrasonic power and NaOH mass fraction on the yield of acorn starch.

[0030] Figure 5d This is a response surface plot showing the effect of the interaction between ultrasonic time and the material-liquid ratio on the yield of acorn starch.

[0031] Figure 5e This is a response surface plot showing the effect of the interaction between ultrasonic power and the liquid-to-material ratio on the yield of acorn starch.

[0032] Figure 5f This is a response surface plot showing the effect of the interaction between ultrasonic power and ultrasonic time on the yield of acorn starch. Detailed Implementation

[0033] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] Example 1: The optimized method for extracting starch from Mongolian oak seeds in this embodiment was achieved through the following steps:

[0035] After the acorns were crushed and defatted, they were divided into several portions. The mass fraction of NaOH, the material-to-liquid ratio, the ultrasonic power and the ultrasonic temperature were selected for single-factor determination. The acorns were subjected to ultrasonic alkaline extraction with NaOH solution under different conditions. After protein removal, washing, drying, grinding and sieving, the starch yield was determined.

[0036] The starch samples treated with the above methods were subjected to Placketet-Burman experiments to analyze the significance of the effect of each single factor on starch yield.

[0037] Based on the results of single-factor experiments, and according to the Box-Behnken central composite experiment, a four-factor, three-level experiment was designed with NaOH mass fraction, material-liquid ratio, ultrasonic power and ultrasonic temperature as independent variables and acorn starch yield as the response value. The variance analysis of the response surface quadratic model was obtained to optimize the acorn starch process.

[0038] The interaction between the four factors with starch yield as the response value was analyzed using Design Expert-12 software. The response surface plot of the effect of the interaction between the two factors on the acorn starch yield was obtained. The slope of the response surface reflects the degree of influence of the interaction between the factors on the response value. The larger the slope, the more significant the influence on the response value.

[0039] The optimal conditions for acorn starch extraction were obtained from the response surface 3D image and results, thus completing the optimization.

[0040] In this embodiment, Mongolian oak acorns were sourced from Dezi Agricultural and Horticultural Flagship Store; pressed corn oil from Shandong Luhua Group Co., Ltd.; alkaline protease from Taian Xindeli Bioengineering Co., Ltd.; cellulase from Shaanxi Rankang Biotechnology Co., Ltd.; DNS colorimetric solution from Fuzhou Feijing Biotechnology Co., Ltd.; petroleum ether from Tianjin Fuyu Fine Chemical Co., Ltd.; and sodium hydroxide, hydrochloric acid, glucose, sodium carbonate, and iodine-potassium iodide were all of analytical grade.

[0041] KQ-500DE CNC Ultrasonic Cleaner: Kunshan Ultrasonic Instrument Co., Ltd.; 101-2AB Electric Heating Blower Drying Oven: Tianjin Test Instrument Co., Ltd.; T6 UV-Vis Spectrophotometer: Beijing Purkinje General Instrument Co., Ltd.; H2050R Benchtop High-Speed ​​Refrigerated Centrifuge: Hunan Xiangyi Laboratory Instrument Development Co., Ltd.; HH-6 Digital Display Constant Temperature Water Bath: Bangxi Instrument Technology (Shanghai) Co., Ltd.; S-3400N Tungsten Filament Scanning Electron Microscope: Shenzhen Century Vision Electronic Equipment Co., Ltd.; D8 ADVANCE X-ray Analyzer: Bruker AXS GmbH, Germany; DSC250 Differential Scanning Calorimeter: TA Instruments, Worth Instruments, USA; Nanoparticle Size and Zeta Potential Analyzer: Malvern Instruments Ltd.

[0042] Preparation of defatted acorn powder:

[0043] Take 100g of acorn powder, crush it using a pulverizer, and pass it through an 80-mesh sieve. Mix the resulting acorn powder with petroleum ether at a ratio of 1:10 and stir for 24 hours to degrease for the first time, then filter. Then stir at a ratio of 1:5 for 24 hours to degrease for the second time, filter, and dry at 45℃ for 1-2 hours to obtain a degreased sample.

[0044] Preparation of acorn starch:

[0045] (1) Alkali washing: 10g of defatted acorn powder was added to NaOH solution, with a material-to-liquid ratio of 1:12. Starch extraction was carried out under the conditions of ultrasonic time of 35min, ultrasonic temperature of 30℃, and ultrasonic power of 300W.

[0046] (2) Protein removal: Wash the lower precipitate with distilled water, adjust the pH of the solution to 10, add alkaline protease (200U / g), place in a 46℃ water bath, enzymatically hydrolyze for 145min, and then remove and cool.

[0047] (3) Washing: Centrifuge at 3000r / min for 15min, add water to the precipitate at a ratio of 1:5, let stand for 4-5h to separate into layers, discard the supernatant, repeat three times, and the resulting precipitate is wet starch.

[0048] (4) Drying: The obtained wet starch was dried at 45℃ for more than 12 hours, ground, and passed through an 80-mesh sieve to obtain refined acorn starch. A glucose standard curve was plotted, yielding the linear regression equation: y = 1.1463x - 0.0156, R02 =0.9991.

[0049] The effect of preparation conditions on the yield of acorn starch was investigated by sequentially using different concentrations of NaOH solution (0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%), with a fixed material-to-liquid ratio of 1:12, ultrasonic time of 35 min, ultrasonic temperature of 30℃, and ultrasonic power of 300 W; and using different material-to-liquid ratios (1:4, 1:6, 1:8, 1:10, 1:12, 1:14, 1:16), with a fixed NaOH mass fraction of 0.3%, ultrasonic time of 35 min, and ultrasonic temperature of 30℃. Ultrasonic power 300W; using different ultrasonic powers (200W, 250W, 300W, 350W, 400W, 450W), with a fixed material-to-liquid ratio of 1:12, NaOH concentration of 0.3%, ultrasonic time of 35min, and ultrasonic temperature of 30℃; using different ultrasonic times (20min, 25min, 30min, 35min, 40min, 45min), with a fixed material-to-liquid ratio of 1:12, NaOH concentration of 0.3%, ultrasonic power of 300W, and ultrasonic temperature of 30℃.

[0050] Based on the results of the single-factor experiments, and according to the Box-Behnken central composite experimental design principle, a four-factor, three-level experiment was designed with NaOH mass fraction, solid-liquid ratio, ultrasonic power, and ultrasonic temperature as independent variables and acorn starch yield as the response value to further optimize the acorn starch extraction conditions. The experimental factors and factor levels are shown in Table 1.

[0051] Table 1. Factors and Levels in the Experimental Design of Response Surface Methodology

[0052]

[0053] The process flow for preparing microporous starch is as follows: acorn starch → citric acid and distilled water → gelatinization → refrigeration → freezing → washing with anhydrous ethanol → drying → acorn microporous starch, prepared using existing technology.

[0054] Performance study of the prepared microporous starch

[0055] For microstructure observation, the powder sample was fixed on a metal sample platform with conductive double-sided adhesive, then palladium was sprayed in a vacuum using an ion sputtering instrument, and finally observed using a tungsten filament scanning electron microscope.

[0056] The sample was thoroughly ground and passed through an 80-mesh sieve. X-ray diffraction was used to analyze the phase composition of the sample, with a Cu target as the radiation source, a wavelength of 1.54186 angstroms, a scanning angle of 10° to 82°, a scanning step size of 0.0134°, and a scanning rate of 8° / min.

[0057] The thermodynamic state of the samples was analyzed using differential scanning calorimetry (DSC) within a test range of 20℃ to 90℃, with a heating rate of 2℃ / min. After the samples were passed through a 100-mesh sieve, 2.5 mg of oven-dried sample was taken, 7.5 mg of water was added, and the samples were compressed into tablets and equilibrated at 4℃ for 1 h. Finally, an empty aluminum box was used as a reference.

[0058] The potential and particle size of acorn starch and microporous starch were measured using a nanoparticle size analyzer and a ZETA potential analyzer.

[0059] Take m1 (g) of acorn microporous starch and place it in a 1.5 mL centrifuge tube. Add an appropriate amount of distilled water, shake well, and let stand for 30 min. Centrifuge at 4000 r / min for 10 min and weigh the precipitate m2 (g). The precipitate is the water-absorbing acorn microporous starch. Calculate the water absorption rate according to the following formula. Use acorn starch as a control group.

[0060] Water absorption rate % = (m2 - m1) / m1 × 100%

[0061] Take m1 (g) of acorn microporous starch and place it in a 1.5 mL centrifuge tube. Add an appropriate amount of edible oil, shake well, let stand for 30 min, centrifuge at 4000 r / min for 10 min, and weigh the precipitate m2 (g). The precipitate is the oil-absorbing acorn microporous starch. Calculate the water absorption rate according to the following formula. At the same time, use untreated acorn starch as a control group.

[0062] Oil absorption rate % = (m2-m1) / m1 × 100%

[0063] Each group was tested in triplicate. The results were processed and tabulated using Origin 2022 software, and the response surface methodology was designed and analyzed using Designexpert 12 software.

[0064] The effect of NaOH mass fraction on the extraction efficiency of acorn starch, by Figure 1 It can be seen that as the mass fraction of NaOH increases, the yield of acorn starch shows a trend of first gradually increasing and then gradually decreasing. When the mass fraction of NaOH is 0.3%, the yield of acorn starch reaches its peak, and as the mass fraction of NaOH continues to increase, the yield of acorn starch gradually decreases.

[0065] Soaking in NaOH solution promotes the separation or loosening of acorn starch from surrounding proteins and other components, thereby facilitating the dissolution of acorn starch. However, when the mass fraction of NaOH exceeds 0.3%, further increasing alkalinity leads to gelatinization of some acorn starch, resulting in starch loss. Simultaneously, the viscosity of the extraction system changes, which is detrimental to the dissolution of starch molecules. Therefore, a NaOH mass fraction of 0.3% was chosen.

[0066] The effect of the material-to-liquid ratio on the extraction efficiency of acorn starch was determined by... Figure 2 It can be seen that, under the premise of keeping the NaOH mass fraction at 0.3% and the ultrasonic time and power constant, the yield of acorn starch shows a trend of first gradually increasing and then gradually decreasing with the increase of the solid-liquid ratio; the peak value is reached at a solid-liquid ratio of 1:12 (g / mL), and the starch extraction is basically completed. However, when the solid-liquid ratio is higher than 1:12 (g / mL), the yield of acorn starch decreases accordingly. This is because a further increase in the volume of alkaline solution may reduce the energy density of ultrasound per unit volume of solution, which is not conducive to the extraction of acorn starch. Therefore, a solid-liquid ratio of 1:12 (g / mL) is selected.

[0067] The effect of ultrasonic power on acorn starch extraction efficiency is shown in the following results. Figure 3 As shown, with increasing ultrasonic power, the yield of acorn starch exhibits a trend of first increasing and then decreasing, reaching its peak at an ultrasonic power of 300W. Increasing the ultrasonic power from 200W to 300W increases the mechanical vibration effect, leading to greater rupture of the acorn cell walls and thus increasing the contact area between the solid matrix and the solvent. Simultaneously, the interaction between proteins and starch is disrupted, promoting starch separation. Therefore, the yield of acorn starch continuously increases. However, the yield of acorn starch begins to decrease when the ultrasonic power exceeds 300W. This is because the high power generates strong mechanical vibration and cavitation effects, causing acorn starch degradation. Furthermore, the increased ultrasonic power intensifies molecular motion within the solution, resulting in rapid temperature rise and partial starch gelatinization. All these factors contribute to the decreased yield of acorn starch. Therefore, an ultrasonic power of 300W is selected.

[0068] The effect of ultrasonic time on acorn starch yield was determined by... Figure 4 It can be seen that the yield of acorn starch increases significantly with the extension of ultrasonic time, reaching a peak at 35 minutes. With further extension of ultrasonic time, the yield of acorn starch decreases. The yield increases before 35 minutes because the cavitation, mechanical, and thermal effects of ultrasonic treatment promote the separation of acorn starch and protein, thus continuously increasing the yield. However, after 35 minutes, the excessive ultrasonic time intensifies the cavitation and thermal effects, leading to starch degradation or gelatinization, ultimately resulting in a decrease in the yield of acorn starch. Therefore, an ultrasonic time of 35 minutes is selected.

[0069] Based on the results of the single-factor experiment, the process was optimized with NaOH mass fraction (A), material-liquid ratio (B), ultrasonic time (C) and ultrasonic power (D) as independent variables and acorn starch yield (R) as the response value. The optimization experiment scheme and results are shown in Tables 2 and 3.

[0070] Table 2. Response Surface Experimental Design and Results

[0071]

[0072]

[0073] Table 3. Analysis of variance (R) of the quadratic response surface model.

[0074]

[0075]

[0076] Note: ** indicates extremely significant difference (P < 0.01); * indicates significant difference (P < 0.05)

[0077] The quadratic multinomial regression equations obtained by fitting the data using Design-Expert software are as follows: A - NaOH mass fraction (%), B - material-to-liquid ratio (g / ml), C - ultrasonic time (min), D - ultrasonic power (w), and R - starch yield (%).

[0078] Y1=0.636742A+0.61875B+0.544092C+0.816017D+0.17245AB+0.042825AC+0.0554AD+0.3638BC+0.14165BD+0.3617CD-1.21972A 2 -1.45408B 2 -1.40757C 2 -1.34268D 2 +77.0277

[0079] As shown in Table 3, the F of the overall model 失拟 =28.07, the regression mean of the model is P<0.0001, indicating that the model is highly significant, with A, B, C, and D all showing highly significant levels. The lack-of-fit term P=0.9527>0.05 is not significant, and the model R... 2 Adj =0.9312>0.9, R 2 =0.9656 > 0.95, proving that the model fits the experiment well. Furthermore, the coefficient of variation (CV) of the response value is 0.4909%, less than 5%, indicating good reproducibility of the model. Based on the F-values ​​of each variable, the order of influence of the four variables on the yield of acorn starch can be determined as follows: ultrasonic power (D) > NaOH mass fraction (A) > material-to-liquid ratio (B) > ultrasonic time (C).

[0080] The interaction between the four factors with starch yield as the response value was analyzed using Design Expert-12 software. The response surface curve results are shown in Figure 5.

[0081] The slope of the response surface reflects the degree of influence of the interactions between various factors on the response value; the steeper the slope, the more significant the impact on the response value. As shown in Figure 5, the slope of the response surface is steeper when the interaction occurs between the independent variables NaOH mass fraction (A) and the material-to-liquid ratio (B), the material-to-liquid ratio (B) and the ultrasonic time (C), and the ultrasonic time (C) and the ultrasonic power (D). The response surfaces obtained when the interaction occurs between the independent variables NaOH mass fraction (A) and the ultrasonic time (C), NaOH mass fraction (A) and the ultrasonic power (D), and the material-to-liquid ratio (B) and the ultrasonic power (D) are gentler than the first three. Therefore, the interaction between AB, BC, and CD has a more significant impact on starch yield than the interaction between AC, AD, and BD.

[0082] The optimal conditions for acorn starch extraction, derived from the 3D response surface methodology (RSM) images and results, are: NaOH mass fraction of 0.329%, solid-liquid ratio of 1:12.566 g / ml, ultrasonic time of 36.813 min, and ultrasonic power of 314.014 W. Under these conditions, the acorn starch yield is 77.433%. Based on practical considerations, the optimal conditions from the RSM analysis were revised to: NaOH mass fraction of 0.33%, solid-liquid ratio of 1:12 g / ml, ultrasonic time of 36 min, and ultrasonic power of 310 W. Three parallel experiments were conducted under these conditions, yielding an average acorn starch yield of 77.41%. The actual value is close to the theoretical value, indicating that the regression model is reasonable and the optimized extraction process is feasible.

Claims

1. An optimized method for extracting starch from Mongolian oak seeds, characterized in that, The method is implemented through the following steps: After crushing the acorns, the powder was passed through an 80-mesh sieve. The resulting acorn powder was mixed with petroleum ether at a mass ratio of 1:10 and stirred for 24 hours for the first degreasing, followed by filtration. Then, the mixture was stirred at a mass ratio of 1:5 for 24 hours for the second degreasing, followed by filtration. The powder was dried at 45℃ for 1-2 hours to complete the degreasing process. The powder was then divided into several portions. The mass fraction of NaOH, the material-to-liquid ratio, the ultrasonic power, and the ultrasonic temperature were selected for single-factor determination. The powder was subjected to ultrasonic alkaline extraction with NaOH solution under different conditions. After protein removal, washing, drying, grinding, and sieving, the starch yield was determined. The starch samples treated with the above methods were subjected to Placketet-Burman experiments to analyze the significance of the effect of each single factor on starch yield. Based on the results of single-factor experiments, and according to the Box-Behnken central composite experiment, a four-factor, three-level experiment was designed with NaOH mass fraction, material-liquid ratio, ultrasonic power and ultrasonic temperature as independent variables and acorn starch yield as the response value. The variance analysis of the response surface quadratic model was obtained to optimize the acorn starch process. The interaction between the four factors with starch yield as the response value was analyzed using Design Expert-12 software. The response surface plot of the effect of the interaction between the two factors on the acorn starch yield was obtained. The slope of the response surface reflects the degree of influence of the interaction between the factors on the response value. The larger the slope, the more significant the influence on the response value. The optimal conditions for acorn starch extraction were obtained from the response surface 3D image and results, thus completing the optimization. Protein removal was performed as follows: the lower precipitate was washed with distilled water, the solution pH was adjusted to 10, alkaline protease (200 U / g) was added, and the solution was enzymatically hydrolyzed in a water bath at 46°C for 145 min, then removed and cooled. The NaOH mass fraction was 0.33%, the material-to-liquid ratio was 1:12 g / ml, the ultrasonic time was 36 min, and the ultrasonic power was 310 W. The quadratic multinomial regression equations obtained by fitting the data using Design-Expert software are as follows: A - NaOH mass fraction (%), B - material-to-liquid ratio (g / ml), C - ultrasonic time (min), D - ultrasonic power (w), and R - starch yield (%). Y1=0.636742A+0.61875B+0.544092C+0.816017D+0.17245AB+0.042825AC+0.0554AD+0.3638BC+0.14165BD+0.3617CD-1.21972A 2 -1.45408B 2 -1.40757C 2 -1.34268D 2 +77.0277。 2. The method according to claim 1, characterized in that, Defatted acorn powder was added to NaOH solution and starch was extracted under ultrasound.

3. The method according to claim 1, characterized in that, Washing was performed as follows: centrifuge at 3000 r / min for 15 min, add water to the precipitate at a mass ratio of 1:5, let stand for 4 h-5 h to separate into layers, discard the supernatant, and repeat three times.

4. The method according to claim 1, characterized in that, Dry at 45°C for at least 12 hours and pass through an 80-mesh sieve.

5. The method according to claim 1, characterized in that, The mass fractions of NaOH solution used in the single-factor experiments were 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.6%; the material-to-liquid ratios were 1:4, 1:6, 1:8, 1:10, 1:12, 1:14, and 1:16 (unit: g / mL); the ultrasonic power was 200W, 250W, 300W, 350W, 400W, and 450W; and the ultrasonic time was 20 min, 25 min, 30 min, 35 min, 40 min, and 45 min.

Images