WO2021150736A2

WO2021150736A2 - Dietary fiber compositions derived from soybean dregs and methods of making the same

Info

Publication number: WO2021150736A2
Application number: PCT/US2021/014388
Authority: WO
Inventors: Lijun Sun
Original assignee: Healthall Laboratory, Inc.
Priority date: 2020-01-24
Filing date: 2021-01-21
Publication date: 2021-07-29
Also published as: WO2021150736A3

Abstract

Provided are dietary fiber compositions obtained from soybean dregs and methods of producing the same. The dietary fiber compositions disclosed herein comprise a significant amount of insoluble dietary fiber, a small amount of soluble dietary fiber and very little protein, and have high visocity, high water retention capacity and high swelling capacity, and therefore have wide applications in food industry.

Description

DIETARY FIBER COMPOSITIONS DERIVED FROM SOYBEAN DREGS AND METHODS OF MAKING THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62/965,696, filed January 24, 2020, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] This disclosure relates to dietary fiber compositions derived from soybean dregs and methods of making the same. The dietary fiber compositions disclosed herein have superior properties such as high viscosity, high swelling or volume expansion ratio, and high water retention capacity and therefore, can have various applications in the food industry as dietary supplements.

BACKGROUND

[0003] Soybean dreg or soybean residue is a byproduct of soybean food industry (e.g., from making tofu and soy milk), generally white or yellowish in color, having a pulp like appearance, and mostly consisting of insoluble remains from processing the soybeans. Soybean dregs is an abundant source of various nutrients such as dietary fibers, proteins, lipids, essential amino acids, minerals and vitamins. However, due to its poor taste and mouthfeel and the presence of certain antinutritional, hard to digest components such as trypsin inhibitors, saponins, and soybean agglutinins, soybean dregs have only limited commercial uses. Conventionally, soybean dregs are used as a human food source in only some Asian countries but more often for livestock consumption or as fertilizer or compost. When not used as foodstuff or fertilizer, soybean dregs as mass waste cause environmental issues because they are highly susceptible to putrefaction. Accordingly, there is a need to develop nutritional food supplements from soybean dregs or residues to improve the efficiency of soybean consumption.

SUMMARY

[0004] In one aspect, provided herein is a dietary fiber composition obtained from soybean dregs or soybean residues. The dietary fiber composition comprises at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95% (w/w) dietary fiber. In certain embodiments, the dietary fiber composition comprises at least 65%, at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, or at least 85% (w/w) insoluble dietary fiber. In certain embodiments, the dietary fiber composition comprises about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11 %, about 12%, about 13%, about 14%, or about 15% (w/w) soluble dietary fiber. In certain embodiments, the dietary fiber composition comprises less than 5%, less than 4%, less than 3%, less than 2%, less than 1 %, or less than 0.5% (w/w) protein. In certain embodiments, the dietary fiber composition has a viscosity of at least 600 mPa.s, at least 650 mPa.s, at least 700 mPa.s, at least 750 mPa.s, at least 800 mPa.s, at least 850 mPa.s, at least 900 mPa.s, at least 950 mPa.s, at least 1000 mPa.s, at least 1100 mPa.s, at least 1200 mPa.s, at least 1300 mPa.s, at least 1400 mPa.s, at least 1500 mPa.s, at least 1600 mPa.s, at least 1700 mPa.s, at least 1800 mPa.s, at least 1900 mPa.s, at least 2000 mPa.s, at least 2100 mPa.s, at least 2200 mPa.s, at least 2300 mPa.s, at least 2400 mPa.s, at least 2500 mPa.s, at least 2600 mPa.s, at least 2700 mPa.s, at least 2800 mPa.s, at least 2900 mPa.s, or at least 3000 mPa.s. In certain embodiments, the dietary fiber composition has a water retention capacity of at least 15 fold, at least 20 fold, at least 25 fold, at least 30 fold, at least 35 fold, at least 40 fold, at least 45 fold, at least 50 fold, at least 55 fold, or at least 60 fold. In certain embodiments, the dietary fiber composition has a swelling capacity of at least 15 fold, at least 20 fold, at least 25 fold, at least 30 fold, at least 35 fold, at least 40 fold, at least 45 fold, at least 50 fold, at least 55 fold, at least 60 fold, or at least 65 fold. In certain embodiments, the dietary fiber composition comprises porous particles.

[0005] In another aspect, provided herein is a method of making a dietary fiber composition having high fiber contents, particularly high contents of insoluble dietary fiber, low protein contents, high viscosity, high water retention capacity and high swelling capacity from soybean dregs or soybean residues. The method comprises the steps of treating the fresh or dried soybean dregs or soybean residues with an alkali such as NaOH or KOH at a concentration between 0.2%-5% (w/w) at a temperature between 50 °C and 100 °C for a period between 0.5 hour and 20 hours, optionally bleaching the alkaline treated material with a bleaching agent, optionally subjecting the material to high pressure homogenization (HPH), and drying and grinding the material to a desired particle size to obtain the dietary fiber composition. In certain embodiments, the alkaline treatment is carried out at an alkali concentration between 0.3% and 1.0% (w/w). In certain embodiments, the alkaline treatment is carried out at a temperature between 70 °C and 85 °C. In certain embodiments, the alkaline treatment is carried out for a period of time between 2 hours and 6 hours.

[0006] In a related aspect, provided herein is a dietary fiber composition produced by any of the methods disclosed herein. The dietary fiber composition comprises at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95% (w/w) dietary fiber. In certain embodiments, the dietary fiber composition comprises at least 65%, at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81 %, at least 82%, at least 83%, at least 84%, or at least 85% (w/w) insoluble dietary fiber. In certain embodiments, the dietary fiber composition comprises about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11 %, about 12%, about 13%, about 14%, or about 15% (w/w) soluble dietary fiber. In certain embodiments, the dietary fiber composition comprises less than 5%, less than 4%, less than 3%, less than 2%, less than 1 %, or less than 0.5% (w/w) protein. In certain embodiments, the dietary fiber composition has a viscosity of at least 600 mPa.s, at least 650 mPa.s, at least 700 mPa.s, at least 750 mPa.s, at least 800 mPa.s, at least 850 mPa.s, at least 900 mPa.s, at least 950 mPa.s, at least 1000 mPa.s, at least 1100 mPa.s, at least 1200 mPa.s, at least 1300 mPa.s, at least 1400 mPa.s, at least 1500 mPa.s, at least 1600 mPa.s, at least 1700 mPa.s, at least 1800 mPa.s, at least 1900 mPa.s, at least 2000 mPa.s, at least 2100 mPa.s, at least 2200 mPa.s, at least 2300 mPa.s, at least 2400 mPa.s, at least 2500 mPa.s, at least 2600 mPa.s, at least 2700 mPa.s, at least 2800 mPa.s, at least 2900 mPa.s, or at least 3000 mPa.s. In certain embodiments, the dietary fiber composition has a water retention capacity of at least 15 fold, at least 20 fold, at least 25 fold, at least 30 fold, at least 35 fold, at least 40 fold, at least 45 fold, at least 50 fold, at least 55 fold, or at least 60 fold. In certain embodiments, the dietary fiber composition has a swelling capacity of at least 15 fold, at least 20 fold, at least 25 fold, at least 30 fold, at least 35 fold, at least 40 fold, at least 45 fold, at least 50 fold, at least 55 fold, or at least 60 fold. In certain embodiments, the dietary fiber composition comprises porous particles.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 shows the particle size distribution of Samples A-D in solution after high pressure homogenization in number weighted differential distribution.

[0008] Figure 2 shows the results of XRPD analysis of Samples A-D and commercial soybean fiber products MJ1 , MP1 , FIBRIM, and FI-1 Soy Fibre.

[0009] Figure 3 shows the scanning electron microscope (SEM) images of Samples A-D and commercial soybean fiber products MJ1, MP1, FIBRIM, and FI-1 Soy Fibre.

DETAILED DESCRIPTION

Dietary Fiber Compositions

[0010] This disclosure relates to high quality dietary fiber compositions derived from soybean dregs. The dietary fiber composition comprises about 80-95% dietary fiber derived from soybean dregs, including about 65-85% insoluble dietary fiber and about 5- 15% soluble dietary fiber. Soybean dregs contain about 50-60% dietary fiber, including both soluble dietary fiber and insoluble dietary fiber. The inventor(s) unexpectedly discovered that the high quality dietary fiber compositions obtained from soybean dregs by the technology disclosed herein have highly desirable properties such as high viscosity, high swelling or volume expansion ratio, and/or high water retention capacity which are not possessed by other soybean fiber products currently available on the market or described in literature.

[0011] Although alkaline treatment has been broadly used to remove protein, bean taste and color of the soybean dregs during fiber extraction from soybean dregs, the inventor(s) unexpectedly discovered that a combination of parameters of the manufacturing process such as treating soybean dregs with alkaline at a certain range of concentrations and temperatures and over a certain period of time had a significant impact on the properties of the final dietary fiber composition. The dietary fiber compositions prepared under certain alkaline conditions not only demonstrated significantly enhanced water retention and swelling properties but also remarkably high viscosity, such that the obtained dietary fiber compositions exhibit a distinct thickening effect. The unique alkaline treatment conditions disclosed herein not only removed protein and most hemicellulose and lignin, but also modified the soybean cellulose structure.

[0012] As demonstrated in the working examples, the soybean dietary fiber compositions disclosed herein have a viscosity of at least 600 mPa.s to up to 3000 mPa.s in 1 % aqueous solution, and/or have a water retention capacity of up to 15-60 times of its own weight. The disclosed soybean dietary fiber compositions have a 2-10 fold improvement with respect to viscosity, swelling and water retention capacity compared to soybean fiber products currently on the market or reported in literature.

Methods of Making the Dietary Fiber Compositions

[0013] The dietary fiber compositions disclosed herein are prepared by the technology disclosed herein from various raw materials derived from soybean such as soybean dregs or soybean residues (which are the residues from making soy milk or tofu), soybean meal (which is the residues after soybean oil extraction), and/or soybean dietary fibers after extraction of soybean proteins. The raw materials are dispersed in water at a ratio of soybean dregs:water ranging from 1 :10 to 1 :50, and then the dispersion is treated with an alkali (such as NaOH, KOH, or any other suitable alkali) at a concentration between about 0.2% and about 5% (w/w) at a temperature of between about 50 °C and about 100 °C for a period between about 0.5 hour to about 20 hours. These parameters can be optimized as needed to achieve the desired viscosity, swelling capacity and/or water retention capacity. For example, if a higher concentration of the alkali is used, a lower temperature and/or a shorter treatment time is required. Likewise, if the dispersion is treated at a higher temperature, a lower concentration of the alkali and/or a shorter treatment time is required. In certain embodiments, the alkali is added to the dispersion at a concentration of between 0.3% and about 1.0% (w/w), for example, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, or about 1 .0% (w/w). In certain embodiments, the alkaline treatment is carried out at a temperature of beween 70 °C and 85 °C, for example, about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, or about 85 °C. In certain embodiments, the alkaline treatment is carried out for between 2 hours and 6 hours, for example, about 2 hours, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about 4.5 hours, about 5 hours, about 5.5 hours, or about 6 hours.

[0014] In certain embodiments, the raw materials are fresh materials which can be milled using a colloid mill and then passed through a 40-mesh or higher filter prior to the alkaline treatment. In certain embodiments, the raw materials are dried materials which can be pulverized to 40 mesh or more prior to the alkaline treatment.

[0015] After the alkaline treatment, optionally a bleaching agent (e.g. H2O2) is added to the mixture to achieve a lighter color of the final product. Without bleaching, the obtained composition has a light yellow or yellow color. The bleaching improves the appearance of the obtained composition such that when the composition is used, for example, as a food supplement or additive, it does not affect the color of the food product. In certain embodiments, the amount of the bleaching agent is between about 0.2% and about 2% (w/w). In certain embodiments, the bleaching temperature is the same as the temperature for the alkaline treatment. In certain embodiments, the bleaching temperature is between about 50 °C and about 90 °C. In certain embodiments, the bleaching time is between about 10 minutes and about 2 hours. Similarly, these parameters may be optimized as needed. The higher concentration of the bleaching agent, the lower bleaching temperature and/or the shorter bleaching time. In certain embodiments, the bleaching step is carried out at a temperature beween 60 °C and 80 °C, for example, about 60 °C, about 61 °C, about 62 °C, about 63 °C, about 64 °C, about 65 °C, about 66 °C, about 67 °C, about 68 °C, about 69 °C, about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, or about 80 °C. In certain embodiments, the bleaching step is carried out for between 30 minutes and 60 minutes, for example, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes. In certain embodiments, the bleaching agent includes one or more of hydrogen peroxide, chlorine dioxide, sodium hypochlorite, and ozone.

[0016] Subsequently the solid fraction is separated from the above reaction mixture by pressure filtration (e.g., at a pressure of between 5 kg/cm² and 30 kg/cm²) or centrifugation (e.g., at about 2000 RCF or above), and redispersed in water at a ratio of treated soybean dregs:water ranging from 1 :20 to 1 :100. An acid is added to adjust the pH to neutral pH. Any suitable acid such as one or more of phosphoric acid, hydrochloric acid, sulfuric acid, citric acid, acetic acid, malic acid, oxalic acid, and lactic acid can be used to adjust pH.

[0017] The redispersed soybean dregs are heated to a temperature of between about 40 °C and about 90 °C and homogenized by a standard high pressure homogenizer at a pressure of between about 10 MPa to about 100 MPa. In certain embodiments, the homogenization step is carried out at a pressure of between 20 MPa and 50 MPa, for example, about 20 MPa, about 25 MPa, about 30 MPa, about 35 MPa, about 40 MPa, about 45 MPa, or about 50 MPa. In certain embodiments, the homogenization step is carried out at a temperature beween 60 °C and 80 °C, for example, about 60 °C, about 61 °C, about 62 °C, about 63 °C, about 64 °C, about 65 °C, about 66 °C, about 67 °C, about 68 °C, about 69 °C, about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, or about 80 °C. Upon alkaline treatment of the soybean dregs, the obtained soybean fiber forms a porous structure. The HPH treatment further reduces the particle size of the soybean fiber such that the porous structure becomes looser. Although HPH is not required to obtain the porous structure or the desired viscocity and water retention capacity, this step further improves the properties of the obtained dietary fiber composition. Subsequently, the solid fraction is obtained by pressure filtration (e.g., at a pressure of between 5 kg/cm² and 30 kg/cm²) or centrifugation (e.g., at about 2000 RCF or above), and further dried to a moisture content of about 15% or less. Any suitable drying method may be used, including but not limited to spray drying, hot air drying, vacuum drying, freeze drying, solvent drying, and/or microwave drying. The dried material is pulverized to about 80 mesh or more, or any desired particle size by a variety of pulverization methods and equipment.

[0018] The inventor(s) have unexpectedly found that by optimizing the three parameters: (i) the concentration of the alkaline solution; (ii) the time of alkaline treatment; and (iii) the temperature of alkaline treatment, the dietary fiber compositions obtained from soybean dregs or residues have superior properties such as a high viscosity ranging from about 600 mPa.s to up to 3000 mPa.s. Surprisingly, no additional treatment such as enzyme treatment is required to achieve the high visocity, which greatly reduces the production cost to obtain a high quality dietary fiber composition.

Applications of the Dietary Fiber Compositions

[0019] The conventional soybean dietary fiber has low viscosity in water, poor water retention capacity and/or poor swelling ability, and is easily precipitated when dispersed in water. As such, the commercially available soybean dietary fiber has limited use in liquid or pasty foods. The dietary fiber compositions disclosed herein has good swelling property, water retention capacity and high viscosity, and remains in a uniform and stable state when dispersed in water, and therefore, can be widely used in liquid or pasty food to improve product quality.

[0020] Dietary fiber is added to bakery/pasta products such as bread, cakes, noodles, biscuits and the like to increase fiber content and lower calorie. Starch and protein in these bakery/pasta products play an important role in the texture and mouthfeel. Any ingredients that strengthen the protein network structure can improve rheological properties of the dough, the quality of the bread and noodles, and any ingredients that break up the protein network structure have the opposite effect. In the past, when the soybean dietary fiber is added in a large amount, the protein content in the flour is diluted, the network structure in the dough is also reduced or disrupted, leading to poor quality and texture of the baking products. The soybean dietary fiber of this invention has a high viscosity and strong water retention capacity, and can form a continuous three- dimensional network structure with a certain viscoelasticity, as shown by the SEM images in the working examples. When added to the flour, the network structure can function like a three-dimensional structure to improve the quality and texture of the baking products.

[0021] Because the dietary fiber compositions disclosed herein have high water retention capacity, it can form certain structure in meat products to prevent syneresis to improve the texture and flavor of the meat products and the same time making meat products rich in dietary fiber.

[0022] The dietary fiber compositions disclosed herein have high viscosity in water and a good mouth feel. It melts quickly without sticky feeling when eaten. It is fine and smooth, and has the function of simulating fat taste. Thus, the dietary fiber compositions disclosed herein can be used to replace fat to make low-fat or zero-fat foods rich in dietary fiber, such as low-fat cream rich in dietary fiber, low-fat ice cream rich in dietary fiber, low- fat or zero-fat yogurt rich in dietary fiber, etc.

[0023] The following examples are intended to illustrate various embodiments of the invention. As such, the specific embodiments discussed are not to be construed as limitations on the scope of the invention. It will be apparent to one skilled in the art that various equivalents, changes, and modifications may be made without departing from the scope of invention, and it is understood that such equivalent embodiments are to be included herein. Further, all references cited in the disclosure are hereby incorporated by reference in their entirety, as if fully set forth herein.

EXAMPLES

Example 1 : Methods of analyses

[0024] Viscosity measurement: 1% (w/w) solution/suspension was prepared by dispersing a sample dietary fiber composition in purified water and kept at 90 °C for 20 minutes. The sample is then treated with a high pressure homogenizer (HPH) under the pressure of 20 MPa. The sample was cooled down to 20 °C for viscosity measurement. The viscosity of the sample was measured using a Brookfield viscometer, spindle # 62 at 12 RPM. [0025] Water retention capacity measurement: 1% (w/w) solution/suspension was prepared by dispersing a sample dietary fiber composition in purified water and kept at 90 °C for 20 minutes. The sample was then treated with a high-pressure homogenizer (HPH) under the pressure of 20 MPa. The sample was cooled down to 20 °C for water retention capacity (WRC) measurement. 100 g of the solution was placed in a filter paper funnel and filtered. After the water stopped dripping, the water-saturated sample was removed and weighed (ml ), and the water retention capacity of the sample was calculated according to the following equation:

WRC = (m1-m)/m, where ml represents the sample weight after water saturation, and m represents the initial dry sample weight.

[0026] Swelling capacity measurement: 0.3 g of a sample dietary fiber compostion was added to a 25 ml glass test tube, along with 20 ml of purified water, mixed by shaking and left at 20°C for 24 hours. The swelling capacity was represented by the fold of volume expansion (ml/g), calculated by the following equation:

SWC (ml/g) = (V1-V)/m, where V1 represents the sample volume after water saturation, and V represents the initial sample volume, and m represents the initial dry sample weight.

Example 2: Preparation of dietary fiber compositions under various conditions

[0027] This example demonstrates that the alkaline treatment is an important step of the disclosed process. The combination of the alkali concentration, alkaline treatment temperature and time has an impact on the viscosity of the obtained dietary fiber compositions.

[0028] When the alkali concentration is low (e.g., less than 0.2% (w/w)), the reaction between the alkali and the dietary fiber is weak, resulting in only a small change in the structure of the composition, and therefore the viscosity and water retention capacity are both low. Under the low alkali conditions, the protein in the raw materials of soybean dregs or soybean residues cannot be effectively removed. Compositions obtained by low concentration alkaline treamtnet had a relatively high protein content and a relatively low fiber content. On the other hand, when the alkali concentration and temperature are too high, the fiber structure is easily disrupted, resulting in excessive decomposition of the fiber, making it difficult to prepare dietary fiber with higher viscosity. Although the combination of high alkali concentration and low treatment temperature may result in dietary fiber compositions having high viscosity, the production efficiency is low and the production cost is high due to the extra cost of waste treatment.

[0029] The process disclosed herein were in general carried out at an alkali concentration of between 0.3% and 1 .0% (w/w) at a temperature between 70 °C and 85°C for between 2 hours and 6 hours.

[0030] Table 1 shows that various samples obtained at various concentrations of NaOH at various temperatures for various periods of time had different viscosity, water retention capacity and protent contents.

[0031] Table 2 shows the viscosity and water retention capacity of various samples obtained when the concentration of NaOH was fixed at 0.5% (w/w) but the temperature and treatment time were varied.

[0032] As shown in Table 2, when the amount of NaOH was fixed at 0.5%, to a certain extent, the higher the treatment temperature and/or the longer the treatment time, the greater the viscosity. However, the viscosity decreased after reaching the maximum value. In particular, when the treatment temperature reached 85 °C, the viscosity reached a maximum of 2850 mPa.s in 3 hours, and then decreased to 2025 mPa.s after 4 hours of treatment. The viscosity reached 2455 mPa.s. for a treatment at 80 °C for 4 hours but when the temperature was lower than 80 °C, it took longer to increase the viscosity gradually. At a lower temperature of 70 °C or 75 °C, the samples were treated for at least 4 hours to reach a viscosity of 1500 mPa.s.

[0033] Table 3 shows the impact of various alkaline concentration, treatment temperature and treatment time on viscosity and/or water retention capacity of various samples.

[0034] As shown in Tables 1-3, the dietary fiber compositions disclosed herein have good water retention capacity. The viscosity does not appear to have a correlation with the water retention capacity. However, the water retention capacity is greatly affected by the treatment temperature and time. To a certain extent, the water retention capacity improved with an increase in treatment temperature and then decreased when the treatment temperature was further increased. Treatment at 70 °C for about 4 hours appeared to achieve the best water retention capacity, up to 55 times to the original dry weight of the samples. The treatment at 50-60 °C achieved a water retention capacity of 28-36 fold, the treatment at 75 °C achieved a water retention capacity of 40-50 fold, and the treatment at 80-85 °C achieved a water retention capacity of 32-48 fold, respectively. Nevertheless, the water retention capacity significantly reduced when the treatment temperature exceeded 90 °C. Although not wishing to be bound by any theory, when the temperature is low, the proportion of insoluble dietary fiber converting to soluble dietary fiber is low, such that more hydrophilic groups are retained. Therefore, even when the viscosity is low, there is still good water retention capacity. When the treatment temperature is higher than 85 °C, although compositions with higher viscosity can be obtained, more hydrophilic groups in the dietary fiber may be converted into a soluble component and removed, resulting in a high viscosity but a reduced water retention capacity.

Example 3: Characterization of Dietary Fiber Composition Samples

[0035] This example demonstrates the characterization of various samples. Samples A-D were prepared under conditions detailed in Table 4. The properties of these samples were compared with commercially available samples MJ1 (a soybean insoluble fiber product purchased from China Pingdingshan Jinjing Biotechnology Co., Ltd.) and MP1 (a soybean insoluble fiber product purchased from Shandong Yuxin Biotehcnology Co., Ltd.). In general, the disclosed dietary fiber compositions have a significantly higher viscosity, comparable or improved water retention capacity and swelling capacity, and significantly lower protein contents compared to the commercial soybean fiber products.

[0036] Samples A-D were obtained by a process disclosed in general in the foregoing paragraphs. Specifically, dry powder of soybean dregs was added to water at a mass ratio of soybean dregs:water = 1:15, and NaOH was added to a concentration of 0.5% (w/w) and incubated at the specified temperature for the specified period of time for each sample. Subsequently, H2O2 was added for bleaching at the same temperature of prior alkaline treatment for a period of time specified in Table 4. The solid fraction was separated by pressure filtration and redispersed in water at a mass ratio of solid fraction:water = 1:15. Hydrochloric acid was added to adjust pH to neutral pH. Sample A was not subjected to homogenization and Samples B-D were subjected to homogenization as specified in Table 4.

[0037] The solid fraction was obtained by pressure filtration, dried by vacuum drying (Samples A and D) or spray drying (Samples B and C) to a moisture content of less than 10% and pulverized to a particle size of 80 mesh or more. Composition and residual analyses were performed on Samples B and D and results are shown in Table 5 below.

[0038] As shown in Table 5, the dietary fiber compositions disclosed herein have a high dietary fiber content (close to 90%), with the majority fraction being insoluble dietary fiber (76-78%), a small amount of soluble dietary fiber (9-12%), and a very low amount of protein residual (0.9-12%). These data demonstrate tthe high quality of the soybean dietary fiber compositions characterized by high purity, high total fiber content and low protein residual.

[0039] Particle size and particle shape analyses were performed on Samples A-D dry samples using a Malvern Morphologi G3S image analyzer. The analyses include the circular equivalent diameter (Table 6), aspect ratio describing the elongation of the particle represented by weight/length (Table 7), and circularity represented by ratio of circumference of a circle to the projected area (Table 8).

[0040] In Tables 6-8, n means weighted by particle number, and v means weighted by volume. D[n, 0.1], D[n, 0.5] and D[n, 0.9] indicate the size at which 10%, 50% or 90% of particles within the distribution are smaller than the listed value based on number weighing. For an example, D[n, 0.9]: 65 pm, means that 90% of the particles are smaller than 65 pm on the number basis. The same notion also applies to volume based weighing and shape analyses. As shown in Tables 6-8, Samples A-D have very similar particle size and shape although the viscosity, water retention capacity and swelling capacity are different.

[0041] Further, particle size analyses in solution after high pressure homogenization were performed on Samples A-D using a Paricle Sizing Systems Accusizer (Model 780 AD, range 1 - 1000 pm range) under the Extinction mode. 1% (w/w) solution/suspension was prepared by dispersing each sample in purified water with stirring at 80-85 °C for 20 minutes. Then the sample was subjected to a high pressure homogenizer (HPH) under the pressure of 20 MPa before being analyzed. The results are shown in Table 9 and Figure 1 .

[0042] As shown in Table 9, there are significant differences in particle sizes of the samples. Samples A and D with a higher viscosity have smaller diameters (mean diameter 1.47 pm and 1.55 pm, respectively, whereas Samples B and C with a lower viscosity have larger diameters (mean diameter 2.96 pm and 3.00 pm, respectively. These particle size analyses were repeated several times and with slightly different sample preparation protocols (e.g. with different HPH instruments and pressures, at different temperatures, or further sonicating the samples before applying to the Accusizer etc.). However, the differences were invariably observed, that is, Samples A and D with a higher viscosity have a smaller particle size than Samples B and C with a lower viscosity.

[0043] The particle size differences of the samples in solution after high pressure homogenization are even more pronounced by particle size distribution. As shown in Figure 1 , Samples A and D with a higher viscosity show a similar particle size distribution toward the lower end of the plot, whereas Samples B and C with a lower viscosity show a particle size distribution centering around 3 pm.

[0044] Comparative structural analyses by X-ray powder diffraction (XRPD) were performed on Samples A-D in comparison with several commercial products, MJ1 , MP1 , FIBRIM 1020 (purchased from Dupont/Danisco), and FI-1 Soy Fibre (purchased from Unique Soy, Fibred, Maryland) to determine the internal structural differences of various soybean insoluble fiber products.

[0045] The structures of several soy dietary fiber powder samples were investigated using an X-ray diffractometer (Rigaku Ultima IV, Japan) with Cu K a radiation at 40 kV and 44 mA, the 2 Q scan range is 10-45/50° with increments of 0.05° at a scanning rate of 1 degree per minute. The Crystallinity index (Cl) of each sample was calculated by a peak height method: 100

where 1002 (2 Q ~ 22.1 °) and IAM ((2 Q ~ 18.3°) represent the intensity (a. u.) of the crystalline and the amorphous contribution. Although it is debatable if Cl quantitatively reflects the crystal/amorphous ratio of the fiber structure, it can be used as a parameter for comparative structural analyses to determine the differences among different fiber samples.

[0046] As shown in Figure 2, Samples A and D with a higher viscosity has substantially higher Cl number than Samples B and C with a lower viscosity. These observations suggest that variations in alkaline treatment surprisingly caused internal structural changes, resulting in products having very high viscosity.

[0047] Flowever, Cl may not be used as the only indicator of viscosity for soybean fiber products made by different methods. The commercial soybean fiber products MJ1 , MP1 , FIBRIM 1020, and FI-1 Soy Fibre were also analyzed by XRPD (Figure 2). MP1 and FIBRIM showed mostly amorphous structure and indeed very low viscosity in 1% solution after HPH treatment, while the viscosity, XRPD profile and Cl of MJ1 were similar to those of Samples B and C. Flowever, FI-1 Soy Fibre, which displayed little viscosity in 1 % solution after HPFH treatment, had a distinct XRPD profile and a very high Cl value.

[0048] The XRPD analyses (Figure 2 and Table 10) reveal that the dietary fiber compositions disclosed herein have a distinct X-ray powder diffraction profile compared with other commercially available soybean fiber products, indicating their distinct internal structure. The Cl correlates with the viscosity of the compositions when prepared using the methods disclosed herein but Cl does not appear to correlate with the viscosity of commercial products. In certain embodiments, the dietary fiber compositions obtained by the methods disclosed herein have a Cl between 0.21 and 0.65.

[0049] The viscosity of FIBRIM and FI-1 Soy Fibre was not measured but estimated to be less than 50 mPa.s. These samples obviously had very low viscosity in water after HPH and both samples formed precipitation and a separated layer readily formed in water suspension.

[0050] Structural analyses by scanning electron microscope (SEM) were performed on Samples A-D to further determine the internal structure of these samples. 1 % (w/w) solution/suspension was prepared by dispersing each sample, including the commercial products MJ1 , MP1 , FIBRIM, and FI-1 Soy Fibre which were used as controls, in purified water with stirring at 80-85 °C for 20 minutes. Then the samples were subjected to a high pressure homogenizer (HPH) under the pressure of 20 MPa. To capture the structural features in the hydrated state, the samples were flash frozen in liquid nitrogen, and lyophilized to dry, sputter coated with platinum and imaged on a JOEL JSM-7001 Scanning electron microscope. For each sample, a number of particles were imaged, images most representative of the observed structural features of a given sample are shown in Figure 3.

[0051] As shown in Figure 3, all samples prepared according to the methods disclosed herein formed porous structural network in solution after HPH. Therefore, the dietary fiber compositions disclosed herein are particularly useful in the food industry when preparing certain food to further improve mouthfeel and other sensory features. These structural features may contribute to the superior water retention capacity and swelling capacity, as well as modest to high viscosity that leads to good thickening/gelling function. Although Samples B and C formed porous structural network, this structural network appear to be more disorganized at a large scale. By contrast, the structural network in Samples A and D appear to be more extensive and better organized, where the fiber network is parallel to each other and interconnected by many strands of thin fiber. These structural features may contribute to the variation in viscosity.

[0052] For comparison, commercial products MJ1 , MP1 , FIBRIM, and FI-1 Soy Fibre were also analyzed by SEM after HPH treatment. As shown in Figure 3, only MJ1 showed a porous but somewhat disorganized network structure that is similar to that of Samples B and C, whereas all other three smaples, MP1 , FIBRIM, and FI-1 Soy-Fibre displayed totally disorganized flake structures. In FI-1 Soy-Fibre, the fiber bundles are the predominant structural features.

Claims

1. A dietary fiber composition comprises at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95% (w/w) dietary fiber, wherein the dietary fiber composition is obtained from soybean dregs or soybean residues.

2. The dietary fiber composition of claim 1 , comprising at least 65%, at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71 %, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, or at least 85% (w/w) insoluble dietary fiber.

3. The dietary fiber composition of claim 1 or claim 2, comprising about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11 %, about 12%, about 13%, about 14%, or about 15% (w/w) soluble dietary fiber.

4. The dietary fiber composition of any one of claims 1 -3, comprising less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or less than 0.5% (w/w) protein.

5. The dietary fiber composition of any one of claims 1-4, wherein the dietary fiber composition has a viscosity of at least 600 mPa.s, at least 650 mPa.s, at least 700 mPa.s, at least 750 mPa.s, at least 800 mPa.s, at least 850 mPa.s, at least 900 mPa.s, at least 950 mPa.s, at least 1000 mPa.s, at least 1100 mPa.s, at least 1200 mPa.s, at least 1300 mPa.s, at least 1400 mPa.s, at least 1500 mPa.s, at least 1600 mPa.s, at least 1700 mPa.s, at least 1800 mPa.s, at least 1900 mPa.s, at least 2000 mPa.s, at least 2100 mPa.s, at least 2200 mPa.s, at least 2300 mPa.s, at least 2400 mPa.s, at least 2500 mPa.s, at least 2600 mPa.s, at least 2700 mPa.s, at least 2800 mPa.s, at least 2900 mPa.s, or at least 3000 mPa.s.

6. The dietary fiber composition of any one of claims 1-5, wherein the dietary fiber composition has a water retention capacity of at least 15 fold, at least 20 fold, at least 25 fold, at least 30 fold, at least 35 fold, at least 40 fold, at least 45 fold, at least 50 fold, at least 55 fold, or at least 60 fold.

7. The dietary fiber composition of any one of claims 1-6, wherein the dietary fiber composition has a swelling capacity of at least 15 fold, at least 20 fold, at least 25 fold, at least 30 fold, at least 35 fold, at least 40 fold, at least 45 fold, at least 50 fold, at least 55 fold, or at least 60 fold.

8. The dietary fiber composition of any one of claims 1-7, comprising particles that form a porous structure upon contact with water.

9. A method of making a dietary fiber composition from soybean dregs or soybean residues, comprising: treating the fresh or dried soybean dregs or soybean residues with an alkali; and drying and grinding the material to a desired particle size to obtain the dietary fiber composition.

10. The method of claim 9, wherein the alkali is NaOH or KOH.

11 . The method of claim 9 or claim 10, wherein the soybean dregs or soybean residues are treated with an alkali at a concentration between 0.2%-5% (w/w).

12. The method of any one of claims 9-11 , wherein the soybean dregs or soybean residues are treated with an alkali at a concentration between 0.3%-1.0% (w/w).

13. The method of any one of claims 9-12, wherein the soybean dregs or soybean residues are treated with an alkali at a temperature between 50 °C and 100 °C.

14. The method of any one of claims 9-13, wherein the soybean dregs or soybean residues are treated with an alkali at a temperature between 70 °C and 85 °C.

15. The method of any one of claims 9-14, wherein the soybean dregs or soybean residues are treated with an alkali for a period between 0.5 hour and 20 hours.

16. The method of any one of claims 9-15, wherein the soybean dregs or soybean residues are treated with an alkali for a period between 2 hours and 6 hours.

17. The method of any one of claims 9-16, further comprising bleaching the alkaline treated material with a bleaching agent.

18. The method of any one of claims 9-17, further comprising subjecting the material to high pressure homogenization (HPH) before drying and grinding.

19. A dietary fiber composition produced by any of the methods of claims 9-18.

20. The dietary fiber composition of claim 19, comprising at least 80% insoluble dietary fiber and having a viscosity of at least 700 mPa.s.