A dietary fiber composition containing beta-glucan from k. marxianus and its use in puffed rice cakes

Abstract

The present application relates to a kind of dietary fiber compositions containing Kluyveromyces marxianus beta-glucan and its application in puffed rice cake, belong to the field of biotechnology.The dietary fiber composition includes the following mass fraction components: Kluyveromyces marxianus beta-glucan compound 5-30 parts, grain powder 40-85 parts, dietary fiber 5-25 parts, natural sweetener 2-10 parts, oil 1-5 parts, emulsifier 0.2-2 parts, leavening agent 0.5-3 parts.The compound is prepared by wet mixing Kluyveromyces marxianus beta-glucan and citrus fiber at a mass ratio of 1:0.5-1:2, adjusting pH to 6.0-7.5, 50-70 DEG C incubation stirring and freeze-drying.The present application significantly improves the retention rate of beta-glucan in high-temperature baking puffing process through pre-compounding technology, improves the puffing degree of the product, and synergistically enhances the production of short-chain fatty acids.

Description

Technical Field

[0001] This invention belongs to the field of biotechnology and relates to a dietary fiber composition containing Kluyveromyces martensii β-glucan and its application in puffed rice cakes. Background Technology

[0002] Dietary fiber, known as the "seventh essential nutrient," plays a vital physiological role in regulating intestinal function, controlling blood sugar and lipids, and preventing obesity and colon cancer. With increasing consumer health awareness, functional snacks rich in dietary fiber have become an important development direction for the food industry. Puffed rice cakes, as a crispy and convenient snack, have a wide consumer base; however, their traditional formulas generally contain low levels of dietary fiber, making it difficult to meet consumer demand for functional foods.

[0003] β-glucan is a class of functional polysaccharides with immunomodulatory, hypoglycemic, cholesterol-lowering, and prebiotic activities. β-glucan from different sources exhibits significant differences in molecular structure and biological activity. Cereal-derived β-glucan is linked by a mixture of β-1,3 and β-1,4 glycosidic bonds, exhibiting a random coil conformation, and its immunomodulatory activity is relatively weak. In contrast, yeast-derived β-glucan is linked by a β-1,3 backbone and β-1,6 branches, forming a unique triple helix conformation, exhibiting stronger immune-activating capabilities and prebiotic effects. However, yeast β-glucan exhibits poor stability during high-temperature heat processing; its triple helix structure is easily destroyed at high temperatures, leading to a significant decrease in biological activity. This characteristic limits the application of yeast β-glucan in high-temperature processed foods such as puffed and baked goods. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a dietary fiber composition containing Kluyveromyces masculinus β-glucan and its application in puffed rice cakes.

[0005] The objective of this invention can be achieved through the following technical solutions: A dietary fiber composition containing Kluyveromyces martensii β-glucan, said dietary fiber composition comprising the following components in parts by weight: 5-30 parts of Kluyveromyces Marcius β-glucan complex, 40-85 parts of cereal flour, 5-25 parts of dietary fiber, 2-10 parts of natural sweetener, 1-5 parts of oil, 0.2-2 parts of emulsifier, and 0.5-3 parts of leavening agent; The preparation method of the Kluyveromyces Marcius β-glucan complex is as follows. Citrus fiber was added to deionized water at a material-to-liquid ratio of 1:5 to 1:15 and stirred for 20 to 60 minutes. Then, Kluyveromyces β-glucan was added at a mass ratio of 1:0.5 to 1:2 of Kluyveromyces β-glucan to citrus fiber and stirred for another 20 to 60 minutes. The pH was adjusted to 6.0 to 7.5 and stirred at 50 to 70°C for 30 to 60 minutes. The mixture was then freeze-dried to obtain the Kluyveromyces β-glucan complex.

[0006] In the technical solution of this invention, pectin and cellulose microfibers in citrus fibers form a three-dimensional network hydrogel structure in water. When the triple helix conformation of Kluyveromyces β-glucan is blended with this hydrogel at pH 6.0-7.5 and 50-70℃, the two form a tight physical cross-link through hydrogen bonds and hydrophobic interactions. This acts as a heat buffer layer and physical barrier during subsequent extrusion puffing or high-temperature baking, delaying the direct transfer of heat to β-glucan molecules and reducing the unwinding of its triple helix structure and degradation of its molecular chains. Simultaneously, Kluyveromyces β-glucan contains many hydrophobic groups and is prone to agglomeration in its dry powder state. Direct addition can lead to uneven distribution in the grain powder, with local concentrations being too high or too low. During pre-blending, the hydrophilic polysaccharides of citrus fibers coat the surface of β-glucan particles, giving them better hydrophilicity and wettability, allowing them to be uniformly dispersed throughout the food matrix during subsequent mixing, slurry preparation, and steaming. Furthermore, citrus fiber and Kluyveromyces Marcius β-glucan produce different proportions of short-chain fatty acids (SCFAs) during gut microbiota fermentation: pectin fermentation mainly produces acetic acid and propionic acid; β-glucan fermentation mainly produces propionic acid, while also producing a certain amount of butyric acid. The combined SCFAs and butyric acid yields are significantly higher than those of single fiber.

[0007] Furthermore, the grain powder is composed of rice flour, glutinous rice flour and buckwheat flour in a weight ratio of (3~4):(2~3):(2~3).

[0008] In the technical solution of this invention, the high-branched starch of glutinous rice flour forms a strong viscous gel during steaming, which coats rice flour and buckwheat flour particles, giving the dough good extensibility and tensile strength. It can also trap more water vapor generated during vaporization, forming thicker and more uniform bubble walls. The dough exhibits optimal viscoelasticity when the ratio of rice flour to glutinous rice flour is between 3:2 and 4:3; a ratio exceeding 4:3 results in an overly sticky dough that is difficult to press into sheets; a ratio below 3:2 causes the bubble walls to rupture easily, reducing puffing. When the amount of buckwheat flour added is between (3~4):(2~3):(2~3), its dietary fiber and rutin help regulate moisture migration, preventing the surface of the dough from forming a crust too quickly during the pre-drying stage and ensuring effective vaporization of internal moisture during baking. Simultaneously, the protein and starch in buckwheat flour form complex dextrin with rice flour, enhancing the crispy texture. Furthermore, buckwheat flour is rich in rutin, dietary fiber, B vitamins, and minerals; rutin has antioxidant properties, improves microcirculation, and helps lower blood sugar. It complements the immunomodulatory function of Kluyveromyces maxima β-glucan, enabling the product to shift from a single function to a multi-functional one.

[0009] Furthermore, the dietary fiber is selected from one or more of inulin, fructooligosaccharides, and resistant dextrin.

[0010] These dietary fibers work synergistically with the citrus fiber in the Kluyveromyces Marcius beta-glucan complex to exert prebiotic functions and promote the production of short-chain fatty acids in the gut.

[0011] Furthermore, the natural sweetener is selected from one or more of erythritol, steviol glycosides, mogrosides, and trehalose.

[0012] In addition to providing sweetness, trehalose also has the additional function of protecting the thermal stability of Kluyveromyces β-glucan, which can reduce its degradation during high-temperature processing.

[0013] Furthermore, the oil is selected from one or more of coconut oil, palm oil, butter, and medium-chain triglyceride oil.

[0014] Oils and fats act as lubricants during extrusion and puffing, reducing friction between materials and processing equipment, while also homogenizing the product's texture and improving its crispness and flavor.

[0015] Furthermore, the emulsifier is selected from one or more of glyceryl monostearate, soybean lecithin, and sucrose fatty acid esters.

[0016] The addition of emulsifiers helps to uniformly disperse oils in aqueous systems, allowing the components to fully blend and improving the processing adaptability of the composition and the textural stability of the product.

[0017] Furthermore, the leavening agent is selected from one or more of sodium bicarbonate, ammonium bicarbonate, and glucono-δ-lactone.

[0018] During the heating process, the leavening agent decomposes to produce carbon dioxide gas, which promotes the puffing of rice cakes, forming a loose and porous structure and increasing the degree of puffing.

[0019] Furthermore, the method for preparing the Kluyveromyces β-glucan includes the following steps: S8-1: Inoculate the strain of Kluyveromyces marxianus into YEPD liquid medium and culture it with shaking at 28-32℃ and 150-250rpm for 24-48 h. Collect the cells by centrifugation and wash them 2-3 times with deionized water. S8-2: The washed bacterial cells were suspended in 2% to 4% NaCl solution at a mass ratio of 1:5 to 1:10, the pH was adjusted to 6.0 to 7.0, and the solution was kept at 50 to 60℃ for 20 to 30 hours. The precipitate was collected by centrifugation. S8-3: Add the precipitate to 0.5-2.0M NaOH solution at a material-to-liquid ratio of 1:8 to 1:15, stir and extract at 80-95℃ for 1-3 hours, and collect the supernatant by centrifugation; S8-4: Adjust the pH of the supernatant to 5.0-6.0 with hydrochloric acid, add 0.5%-2% hydrolytic protease by volume of the supernatant, and enzymatically hydrolyze at 50-60℃ for 4-8 hours. Centrifuge to collect the precipitate. S8-5: Wash the precipitate with deionized water until neutral, add 2 to 5 times the volume of the precipitate in anhydrous ethanol, centrifuge, collect the precipitate, freeze dry, and obtain the Kluyveromyces β-glucan. The weight-average molecular weight of the Kluyveromyces β-glucan is 80-300 kDa.

[0020] In the technical solution of this invention, the aforementioned molecular weight range is achieved by controlling the alkaline extraction temperature, time, and enzymatic hydrolysis conditions. β-glucan with a molecular weight within this range retains the immunomodulatory activity of the triple helix structure while also exhibiting good water dispersibility, which facilitates the formation of a uniform pre-compound with citrus fiber in subsequent processes. While a molecular weight that is too small is easily dispersed, the triple helix structure is incomplete, resulting in weak immunomodulatory activity; conversely, a molecular weight that is too large reduces solubility, making it difficult to uniformly compound with citrus fiber. The molecular weight range of 80~300kDa achieves a balance between the two, allowing for sufficient hydrogen bond cross-linking with citrus fiber during pre-compounding and uniform distribution in the puffed rice cake.

[0021] A method for preparing a dietary fiber composition containing Kluyveromyces martensii β-glucan includes the following steps: S9-1: Weigh out the grain powder, dietary fiber, natural sweetener, and leavening agent according to the formula, put them into a three-dimensional mixer and mix for 10-30 minutes to obtain a dry mixture. S9-2: Place the oil and emulsifier in a water bath at 40~60℃ and heat and stir for 10~30 minutes to obtain an oil phase mixture; S9-3: The dry mixture and the Kluyveromyces β-glucan complex are put into a high-speed mixer. While stirring, the oil phase mixture is sprayed in. Stirring is continued for 5 to 15 minutes to obtain the total mixture. The mixture is then pulverized and passed through a 40 to 80 mesh sieve to obtain the dietary fiber composition.

[0022] The preparation method employs a stepwise mixing strategy, first dry-mixing the powdered components evenly, and then adding the oil phase mixture in the form of spray, which can effectively avoid localized oil aggregation and ensure the uniform distribution of each component.

[0023] The application of a dietary fiber composition containing Kluyveromyces martensii β-glucan in the preparation of puffed rice cakes, wherein the preparation method of the puffed rice cakes includes the following steps: S10-1: Mix the dietary fiber composition with water at a mass ratio of 100:25~100:45 to form a paste, steam and knead at 100~110℃ for 20~40 minutes, press it into a sheet with a thickness of 1.5~3mm by a pressing roller, and then cut it into a round cake with a diameter of 3~6cm. S10-2: Place the dough in a hot air drying oven at 40~60℃ and dry for 1~3 hours until the moisture content is 10%~15%, then let it stand at room temperature for 6~8 hours to mature. S10-3: Place the dried rice cake dough in a baking oven and bake at 180~240℃ for 30~90s. Spray the sugar icing liquid onto the surface of the rice cake using a sugar spraying machine. The sugar icing layer is made of white sugar and gelatin in a mass ratio of 100:1~100:5. Dry the mixture at 60~80℃ until snowflake-like sugar icing forms on the surface, thus obtaining the puffed rice cake.

[0024] The beneficial effects of this invention are: (1) This invention effectively solves the technical problem of easy degradation of yeast β-glucan during high-temperature baking and puffing by pre-combining it with Kluyveromyces Marcius β-glucan. Citrus fiber acts as a protective matrix, coating the surface of β-glucan molecules and playing a role in heat buffering and physical isolation during high-temperature processing. At the same time, the high water-holding capacity of citrus fiber can regulate the water activity of the system and reduce the thermal degradation of β-glucan. In addition, the pectin in citrus fiber and β-glucan produce complementary short-chain fatty acid profiles during intestinal fermentation, and the combination of the two can promote intestinal health more comprehensively than single fiber.

[0025] (2) The puffed rice cakes prepared by this invention have a delicate texture and no off-flavor, and there is no significant quality difference compared with traditional puffed rice cakes. At the same time, the total dietary fiber content of the product can reach 12%~18%, which is a high dietary fiber food; it can significantly increase the production of short-chain fatty acids by intestinal flora; and it also has the potential function of regulating intestinal flora and enhancing immunity. Detailed Implementation

[0026] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0027] It should be noted that, unless otherwise specified, the present invention does not specifically limit the source of the raw materials used in the following embodiments. Commercially available products or products prepared by conventional preparation methods that are well known to those skilled in the art can be used. Experimental methods that do not specify specific conditions are all conventional methods and conventional conditions well known in the art.

[0028] In the following examples, the preparation method of Kluyveromyces Marcius β-glucan is as follows: Kluyveromyces marxianus (purchased from Wuhan Gray Algae Biotechnology Co., Ltd., catalog number HZB125979) strain was inoculated into YEPD liquid medium and cultured at 30℃ and 200 rpm for 36 h with shaking. The cells were collected by centrifugation and washed three times with deionized water. The washed cells were then suspended in 3% NaCl solution at a mass ratio of 1:8, the pH was adjusted to 6.5, and the mixture was incubated at 55℃ for 24 h. The precipitate was collected by centrifugation. The precipitate was added to 1.0 M NaOH solution at a material-to-liquid ratio of 1:10 and extracted by stirring at 90℃ for 2 h. The supernatant was collected by centrifugation. The pH of the supernatant was adjusted to 5.5 with hydrochloric acid, and 1% (by volume) of hydrolytic protease was added. Enzymatic hydrolysis was carried out at 55℃ for 6 h, and the precipitate was collected by centrifugation. The precipitate was washed with deionized water until neutral, and three times its volume of anhydrous ethanol was added to precipitate the precipitate. After centrifugation, the precipitate was collected, freeze-dried, and the resulting product was Kluyveromyces marxianus β-glucan. The β-glucan was found to have a weight-average molecular weight of 150 kDa and a purity of 85.6%.

[0029] The following examples illustrate the preparation method of Kluyveromyces Marcius β-glucan complex: Citrus fiber (total dietary fiber content ≥75%, pectin content ≥25%, water holding capacity ≥10 g water / g fiber) was added to deionized water at a material-to-liquid ratio of 1:10 and stirred for 30 min. Then, the Kluyveromyces β-glucan weighed according to the formula was added and stirred for another 30 min. The pH was adjusted to 6.8 with sodium bicarbonate, and the mixture was kept at 60℃ and stirred for 45 min. Finally, it was freeze-dried to obtain the Kluyveromyces β-glucan complex.

[0030] Example 1

[0031] This embodiment provides a dietary fiber composition containing Kluyveromyces maxima β-glucan, comprising the following components in parts by weight: 10 parts of Kluyveromyces maxima β-glucan complex, 70 parts of cereal flour (rice flour: glutinous rice flour: buckwheat flour = 3.5:2.5:2.5), 10 parts of inulin, 5 parts of erythritol, 2 parts of coconut oil, 0.5 parts of glyceryl monostearate, and 1 part of sodium bicarbonate. In the Kluyveromyces β-glucan complex, the mass ratio of β-glucan to citrus fiber is 1:1.

[0032] The preparation method of the dietary fiber composition in this embodiment is as follows: S9-1: Weigh out the cereal powder, inulin, erythritol and sodium bicarbonate according to the ratio, put them into a three-dimensional mixer, mix at 20 rpm for 20 min to obtain a dry mixture. S9-2: Coconut oil and glyceryl monostearate are heated and stirred in a 50°C water bath for 20 min to obtain an oil phase mixture; S9-3: The dry mixture and the Kluyveromyces β-glucan complex were put into a high-speed mixer, and the oil phase mixture was sprayed in while stirring. The mixture was stirred for 10 min to obtain the total mixture. The mixture was then pulverized and passed through a 60-mesh sieve to obtain the dietary fiber composition. The dietary fiber composition obtained in this embodiment is a uniform powder with a natural color, no clumping, and a moisture content of 5.2%.

[0033] The obtained dietary fiber composition was used to prepare puffed rice cakes, and the specific method is as follows: S10-1: Mix the dietary fiber composition with water at a mass ratio of 100:35 to form a paste, place it in a steaming machine and steam at 105℃ for 30 minutes, press it into a sheet with a thickness of 2 mm by a pressing roller, and then cut it into a round cake with a diameter of 4 cm. S10-2: Place the dough in a hot air drying oven at 50℃ and dry for 2 hours until the moisture content is 12%, then let it stand at room temperature for 7 hours to mature. S10-3: Place the dried rice cake dough in a baking oven and bake at 200℃ for 60 seconds. Spray the sugar icing liquid onto the surface of the rice cake using a sugar spraying machine. The sugar icing layer is made of white sugar and gelatin in a mass ratio of 100:3. Dry at 70℃ until snowflake-like sugar icing forms on the surface to obtain the puffed rice cake.

[0034] Example 2

[0035] The difference between this embodiment and Embodiment 1 is only that a dietary fiber composition containing Kluyveromyces β-glucan contains the following components in parts by weight: 5 parts of Kluyveromyces β-glucan complex, 70 parts of cereal flour (rice flour: glutinous rice flour: buckwheat flour = 3.5:2.5:2.5), 10 parts of inulin, 5 parts of erythritol, 2 parts of coconut oil, 0.5 parts of glyceryl monostearate, and 1 part of sodium bicarbonate; Everything else is the same as in Example 1.

[0036] Example 3

[0037] The difference between this embodiment and Embodiment 1 is only that a dietary fiber composition containing Kluyveromyces β-glucan contains the following components in parts by weight: 30 parts of Kluyveromyces β-glucan complex, 70 parts of cereal flour (rice flour: glutinous rice flour: buckwheat flour = 3.5:2.5:2.5), 10 parts of inulin, 5 parts of erythritol, 2 parts of coconut oil, 0.5 parts of glyceryl monostearate, and 1 part of sodium bicarbonate; Everything else is the same as in Example 1.

[0038] Example 4

[0039] The only difference between this embodiment and Example 1 is that in the Kluyveromyces Marcius β-glucan complex, the mass ratio of β-glucan to citrus fiber is 1:0.5; all other aspects are the same as in Example 1.

[0040] Example 5

[0041] The only difference between this embodiment and Example 1 is that in the Kluyveromyces Marcius β-glucan complex, the mass ratio of β-glucan to citrus fiber is 1:1.5; all other aspects are the same as in Example 1.

[0042] Example 6

[0043] The only difference between this embodiment and Example 1 is that in the Kluyveromyces Marcius β-glucan complex, the mass ratio of β-glucan to citrus fiber is 1:2; all other aspects are the same as in Example 1.

[0044] Example 7

[0045] The only difference between this embodiment and Embodiment 1 is that the grain powder is composed of rice flour, glutinous rice flour and buckwheat flour in a mass ratio of 3:2:2; all other aspects are the same as in Embodiment 1.

[0046] Example 8

[0047] The only difference between this embodiment and Embodiment 1 is that the grain powder is composed of rice flour, glutinous rice flour and buckwheat flour in a mass ratio of 4:3:3; all other aspects are the same as in Embodiment 1.

[0048] Comparative Example 1 The only difference between this comparative example and Example 1 is that it does not contain the Kluyveromyces maxima β-glucan complex, and the mass fraction of inulin is adjusted to 20 parts to compensate for the total amount of dietary fiber; otherwise, it is the same as Example 1.

[0049] Comparative Example 2 The only difference between this comparative example and Example 1 is that the Kluyveromyces β-glucan and citrus fiber are not pre-combined, but are directly mixed with other components in dry powder form; otherwise, they are the same as in Example 1.

[0050] Comparative Example 3 The only difference between this comparative example and Example 1 is that it does not contain citrus fiber; all other aspects are the same as Example 1.

[0051] Comparative Example 4 The only difference between this comparative example and Example 1 is that the pH is not adjusted in the preparation method of the Kluyveromyces β-glucan complex; all other aspects are the same as in Example 1.

[0052] Comparative Example 5 The only difference between this comparative example and Example 1 is that the cereal powder does not contain buckwheat flour; otherwise, they are the same as Example 1.

[0053] Comparative Example 6 The only difference between this comparative example and Example 1 is that oat β-glucan is used instead of Max Kluyveromycin β-glucan; all other aspects are the same as in Example 1.

[0054] Comparative Example 7 The only difference between this comparative example and Example 1 is that it uses a combination of Kluyveromyces Marcius β-glucan with a weight-average molecular weight of 50 kDa and citrus fiber; all other aspects are the same as in Example 1.

[0055] Comparative Example 8 The only difference between this comparative example and Example 1 is that it uses a combination of Kluyveromyces Marcius β-glucan with a weight-average molecular weight of 500 kDa and citrus fiber; all other aspects are the same as in Example 1.

[0056] Performance testing Determination of β-glucan retention rate of Kluyveromyces martensii: The determination was carried out in accordance with GB / T 22221-2008 standard. Each sample was measured in parallel 3 times and the average value was taken.

[0057] Expansion degree determination: Take the cake blank before baking and measure its volume V0. Immerse the cake blank in a graduated cylinder filled with rapeseed and the volume of rapeseed discharged is the volume of the cake blank. Take the puffed rice cake after baking and measure its volume V1 using the rapeseed replacement method. Calculate the corresponding expansion degree V1 / V0.

[0058] Determination of total dietary fiber content: Puffed rice cakes were pulverized and passed through a 60-mesh sieve, defatted, and dried. They were then treated with heat-resistant α-amylase (pH 6.0, 100℃, 30 min), protease (pH 7.5, 60℃, 30 min), and glucosidase (pH 4.5, 60℃, 30 min), respectively. Four volumes of 95% ethanol were added, and the precipitate was collected by centrifugation, dried, and weighed. Protein and ash content were deducted. The TDF (%) was calculated as follows: (precipitate mass - protein content - ash content) / dry weight of sample × 100%.

[0059] In vitro short-chain fatty acid (SCFA) production determination: Fresh feces from three healthy adults with no history of antibiotics and no intestinal diseases were mixed in equal proportions and added to the fermentation medium containing tryptone, yeast extract, NaCl, K₂HPO₄, MgSO₄, CaCl₂, vitamin K₁, heme chloride, and cysteine, with a pH of 6.8. Puffed rice cake was pulverized and passed through an 80-mesh sieve and added as substrate to the fermentation flask at 1% (w / v). The mixture was anaerobic at 37°C for 24 h. SCFA determination: 1 mL of fermentation broth was mixed with 0.2 mL of 25% metaphosphate, centrifuged, and the supernatant was collected. The contents of acetic acid, propionic acid, and butyric acid were determined by gas chromatography, and the total amounts were calculated. The blank control group (without added substrate) was used as background subtraction.

[0060]

[0061] Based on the test data above, we can draw the following conclusions: (1) The key performance indicators such as β-glucan retention rate, puffing degree, and total SCFA in Examples 1-8 are significantly better than those in Comparative Examples 1-8. This indicates that the present invention significantly improves the thermal stability of β-glucan in high-temperature processing, the puffed and crispy taste of the product, and the intestinal prebiotic activity through wet pre-combination of Max Kluyveromyces β-glucan with citrus fiber, specific grain powder compounding, and optimized baking and puffing process.

[0062] (2) Comparing Examples 1 and 4-6, it can be seen that when the mass ratio of β-glucan to citrus fiber increases from 1:0.5 to 1:2, the β-glucan retention rate increases from 82.3% to 89.0%, the total SCFA increases from 56.8 μmol / mL to 60.3 μmol / mL, and the swelling degree increases from 3.9 to 4.4; while the increase in retention rate slows down after the ratio exceeds 1:2, proving that the preferred mass ratio of 1:1 to 1:1.5 in this invention achieves the best balance between thermal protection and prebiotic synergy.

[0063] (3) Comparing Example 1 and Example 2-3, it can be seen that when the amount of Kluyveromyces β-glucan complex added is reduced from 10 parts to 5 parts, the total amount of SCFA decreases by 5.6%; when the amount added is increased to 30 parts, the retention rate decreases by 3.1%, the expansion degree decreases by 0.4, and the total amount of SCFA only increases slightly by 1.4%. This indicates that excessive amount of complex added will lead to a decrease in retention rate and inhibit expansion due to insufficient protection of β-glucan.

[0064] (4) Comparing Example 1 and Comparative Examples 2-4, it can be seen that using simple dry mixing (Comparative Example 2) reduced the β-glucan retention rate by 15.4 percentage points and SCFA by 15.5%; removing citrus fiber (Comparative Example 3) reduced the retention rate by 24.1 percentage points and SCFA by 22.2%; and not adjusting the pH during pre-compounding (Comparative Example 4) reduced the retention rate by 9.3 percentage points and SCFA by 12.6%. This proves that the pre-compounding process, the presence of citrus fiber, and the control of pH 6.0-7.5 work synergistically and are indispensable.

[0065] (5) Comparing Example 1 and Comparative Example 5, it can be seen that when the cereal powder does not contain buckwheat flour, the degree of puffing decreases from 4.2 to 3.5, and the total amount of SCFA decreases from 58.6 to 55.4 μmol / mL. This proves that the dietary fiber and resistant starch in buckwheat flour not only help maintain the uniform distribution of moisture and promote puffing, but also have a certain prebiotic synergistic effect.

[0066] (6) Comparing Example 1 and Comparative Example 6, it can be seen that after replacing the β-glucan from Kluyveromyces martensii with oat β-glucan, the retention rate decreased slightly, but the total amount of SCFA decreased significantly by 16.6%. This indicates that the β-glucan from Kluyveromyces martensii has stronger prebiotic activity due to its unique β-1,3 / β-1,6 triple helix structure, and this effect cannot be replaced by cereal β-glucan.

[0067] (7) Comparing Example 1 and Comparative Examples 7-8, it can be seen that when the molecular weight of Kluyveromyces β-glucan is 50 kDa, although the retention rate is as high as 89.9%, the total SCFA is only 44.2 μmol / mL, indicating that the molecular weight is too small, which leads to the destruction of the triple helix structure and loss of fermentability. When the molecular weight is 500 kDa, the retention rate drops to 75.4%, the expansion degree drops to 3.5, and the SCFA is only 47.8 μmol / mL, proving that the molecular weight range of 80-300 kDa is the best window to balance thermal stability and prebiotic activity.

[0068] The dietary fiber composition of this invention utilizes the three-dimensional network structure of citrus fiber to form a thermal protective shield for β-glucan by wet pre-compounding with Kluyveromyces martensii β-glucan (specific ratio, pH 6.0-7.5, and stirring at 50-70℃), significantly improving its retention rate in high-temperature baking and puffing processes. Simultaneously, the pre-compounded complex produces synergistically enhanced short-chain fatty acids during intestinal fermentation, particularly butyric acid, with a substantial increase in yield. Combined with an optimized ratio of rice flour, glutinous rice flour, and buckwheat flour, this invention achieves multiple benefits in the field of functional puffed foods, including improved processing stability, quality, and prebiotic activity.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention are still within the scope of the present invention.

Claims

1. A dietary fiber composition containing Kluyveromyces martensii β-glucan, characterized in that, The dietary fiber composition comprises the following components in parts by weight: 5-30 parts of Kluyveromyces Marcius β-glucan complex, 40-85 parts of cereal flour, 5-25 parts of dietary fiber, 2-10 parts of natural sweetener, 1-5 parts of oil, 0.2-2 parts of emulsifier, and 0.5-3 parts of leavening agent; The preparation method of the Kluyveromyces Marcius β-glucan complex is as follows. Citrus fiber was added to deionized water at a material-to-liquid ratio of 1:5 to 1:15 and stirred for 20 to 60 minutes. Then, Kluyveromyces β-glucan was added at a mass ratio of 1:0.5 to 1:2 of Kluyveromyces β-glucan to citrus fiber and stirred for another 20 to 60 minutes. The pH was adjusted to 6.0 to 7.5 and stirred at 50 to 70°C for 30 to 60 minutes. The mixture was then freeze-dried to obtain the Kluyveromyces β-glucan complex.

2. The dietary fiber composition containing Kluyveromyces martensii β-glucan according to claim 1, characterized in that, The grain flour is composed of rice flour, glutinous rice flour and buckwheat flour in a weight ratio of (3~4):(2~3):(2~3).

3. The dietary fiber composition containing Kluyveromyces masculinus β-glucan according to claim 1, characterized in that, The dietary fiber is selected from one or more of inulin, fructooligosaccharides, and resistant dextrin.

4. The dietary fiber composition containing Kluyveromyces martensii β-glucan according to claim 1, characterized in that, The natural sweetener is selected from one or more of erythritol, steviol glycosides, mogrosides, and trehalose.

5. A dietary fiber composition containing Kluyveromyces martensii β-glucan according to claim 1, characterized in that, The oil is selected from one or more of coconut oil, palm oil, butter, and medium-chain triglyceride oil.

6. The dietary fiber composition containing Kluyveromyces martensii β-glucan according to claim 1, characterized in that, The emulsifier is selected from one or more of glyceryl monostearate, soybean lecithin, and sucrose fatty acid esters.

7. The dietary fiber composition containing Kluyveromyces martensii β-glucan according to claim 1, characterized in that, The leavening agent is selected from one or more of sodium bicarbonate, ammonium bicarbonate, and glucono-δ-lactone.

8. The dietary fiber composition containing Kluyveromyces martensii β-glucan according to claim 1, characterized in that, The method for preparing the Kluyveromyces β-glucan includes the following steps: S8-1: Inoculate the strain of Kluyveromyces marxianus into YEPD liquid medium and culture it with shaking at 28-32℃ and 150-250rpm for 24-48 h. Collect the cells by centrifugation and wash them 2-3 times with deionized water. S8-2: The washed bacterial cells were suspended in 2% to 4% NaCl solution at a mass ratio of 1:5 to 1:10, the pH was adjusted to 6.0 to 7.0, and the solution was kept at 50 to 60℃ for 20 to 30 hours. The precipitate was collected by centrifugation. S8-3: Add the precipitate to 0.5-2.0M NaOH solution at a material-to-liquid ratio of 1:8 to 1:15, stir and extract at 80-95℃ for 1-3 hours, and collect the supernatant by centrifugation; S8-4: Adjust the pH of the supernatant to 5.0-6.0 with hydrochloric acid, add 0.5%-2% hydrolytic protease by volume of the supernatant, and enzymatically hydrolyze at 50-60℃ for 4-8 hours. Centrifuge to collect the precipitate. S8-5: Wash the precipitate with deionized water until neutral, add 2 to 5 times the volume of the precipitate in anhydrous ethanol, centrifuge, collect the precipitate, freeze dry, and obtain the Kluyveromyces β-glucan. The weight-average molecular weight of the Kluyveromyces β-glucan is 80-300 kDa.

9. A method for preparing a dietary fiber composition containing Kluyveromyces martensii β-glucan as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S9-1: Weigh out the grain powder, dietary fiber, natural sweetener, and leavening agent according to the formula, put them into a three-dimensional mixer and mix for 10-30 minutes to obtain a dry mixture. S9-2: Place the oil and emulsifier in a water bath at 40~60℃ and heat and stir for 10~30 minutes to obtain an oil phase mixture; S9-3: The dry mixture and the Kluyveromyces β-glucan complex are put into a high-speed mixer. While stirring, the oil phase mixture is sprayed in. Stirring is continued for 5 to 15 minutes to obtain the total mixture. The mixture is then pulverized and passed through a 40 to 80 mesh sieve to obtain the dietary fiber composition.

10. The use of a dietary fiber composition containing Kluyveromyces martensii β-glucan as described in any one of claims 1 to 8 in the preparation of puffed rice cakes, characterized in that, The method for preparing the puffed rice cake includes the following steps: S10-1: Mix the dietary fiber composition with water at a mass ratio of 100:25~100:45 to form a paste, steam and knead at 100~110℃ for 20~40 minutes, press it into a sheet with a thickness of 1.5~3mm by a pressing roller, and then cut it into a round cake with a diameter of 3~6cm. S10-2: Place the dough in a hot air drying oven at 40~60℃ and dry for 1~3 hours until the moisture content is 10%~15%, then let it stand at room temperature for 6~8 hours to mature. S10-3: Place the dried rice cake dough in a baking oven and bake at 180~240℃ for 30~90s. Spray the sugar icing liquid onto the surface of the rice cake using a sugar spraying machine. The sugar icing layer is made of white sugar and gelatin in a mass ratio of 100:1~100:

5. Dry the mixture at 60~80℃ until snowflake-like sugar icing forms on the surface, thus obtaining the puffed rice cake.

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