Low GI noodles comprising nanocrystallized fibrous cell walls extracted from bamboo green and methods of making same

Abstract

The invention provides noodles with a low-GI characteristic and a preparation method of the noodles. The noodles with the low GI characteristic comprise nano bamboo fiber cell walls extracted from bamboo green, wheat flour, water and edible salt, the mass ratio of the nano bamboo fiber cell walls to the wheat flour is 0.3%-0.6%, and the nano bamboo fiber cell walls are edible; cellulose in cell walls of the nanocrystallized bamboo fibers has the crystallinity of 80%-95%; the nanocrystallized bamboo fiber cell wall has one-dimensional characteristics, the transverse size is less than 100 nm, and the longitudinal size is more than 1 [mu] m; the dispersion liquid of the nanocrystallized bamboo fiber cell walls in the water has the viscosity of 200 Pas or above when the mass concentration of the nanocrystallized bamboo fiber cell walls is 0.5% and keeps stable within the temperature range of 5-40 DEG C.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of food processing, and more particularly, to a low GI noodle comprising nanofiber cell wall extracted from bamboo green and a method for preparing the same. BACKGROUND

[0002] Noodle is a major form of staple food for human beings, which is basically made by mixing wheat flour with water and shaping into noodle, and is usually cooked by boiling. Other common cooking methods also include stir-frying, salad and braising after boiling, steaming, etc.

[0003] Among the many properties of noodles, the cook is particularly concerned about the breakage rate and the mouthfeel after cooking. Noodles that are easy to break are not popular. The breakage resistance of noodles can be measured by the breakage rate. The breakage rate includes cooked breakage rate and natural breakage rate. The cooked breakage rate refers to the percentage of the number of breakage after the noodles are cooked. The natural breakage rate refers to the probability of breakage of a material or object under certain conditions without external force. The definitions of cooked breakage rate and natural breakage rate can be found in the national standard GB / T 40636-2021 "Dried Noodle". The standard also defines the cooking loss rate. The cooked breakage rate, natural breakage rate and cooking loss rate should all be as low as possible. In addition, the cooked noodles should generally have a smooth, soft but tough mouthfeel.

[0004] As a high-starch food made of refined wheat flour, noodles are not suitable for consumers who have problems with blood sugar, such as diabetic patients, because they have a high glycemic index (GI) and can easily cause rapid postprandial blood sugar rise. Therefore, many studies have been conducted to develop low GI noodles. Adding dietary fiber to the noodle formula is a common research direction.

[0005] Edible cellulose is a typical representative of insoluble dietary fiber, which cannot be digested by humans and is of great importance to promoting intestinal peristalsis and defecation. Because it does not provide energy but can increase satiety, it is widely used as an additive in weight loss meals.

[0006] In addition to the basic physiological functions described above, the understanding of the effect of dietary fiber on blood glucose control is also deepening. Previously, it has been recognized that the benefits of dietary fiber on blood glucose mainly lie in delaying sugar absorption, reducing blood glucose fluctuations, improving insulin sensitivity, etc. It helps to maintain stable blood glucose by slowing down the digestive process, regulating intestinal function, etc., especially for people with diabetes or high blood sugar. It forms a viscous gel-like material after water, which wraps the carbohydrates in food, slows down their decomposition and absorption speed in the intestine. At the same time, long-term intake of sufficient dietary fiber can improve the sensitivity of cells to insulin. Studies have shown that increasing dietary fiber intake can effectively reduce the risk of type 2 diabetes. Fiber regulates the balance of intestinal flora, promotes the production of short-chain fatty acids (such as butyric acid), which can directly act on pancreatic beta cells to enhance insulin secretion function. Therefore, dietary fiber has been proposed as a food additive to assist in controlling blood glucose based on the above understanding. For example, Chinese application CN202510726682.2 discloses a noodle with blood glucose control function and a preparation method, in which dietary fiber is added to flour-based food as an auxiliary blood glucose agent.

[0007] Nanocellulose refers to cellulose materials with dimensions in the nanometer range. Compared to ordinary cellulose, nanocellulose has more unique properties, such as high specific surface area, high hydrophilicity, etc., and has the potential to achieve more unique functions. Some nanofiber dietary fibers have been developed to provide further functions. For example, Chinese application 202411037355.8 discloses a nanofiber burdock functional dietary fiber and a preparation method thereof, which is used to provide starch digestion inhibition and hypoglycemic activity. The method uses ultrasonic treatment in combination with complex enzymes to effectively decompose insoluble dietary fiber in burdock and change the spatial structure of insoluble dietary fiber in burdock, preparing nanofiber burdock functional dietary fiber with a particle size of 200-600 nm, which can inhibit the activity of amylase and glucosidase and achieve the effect of reducing blood sugar.

[0008] The current mechanisms for controlling blood glucose using dietary fiber mainly include: (i) replacing starch to provide satiety to reduce starch intake; (ii) forming a gel after absorbing water to physically wrap starch to slow down its digestion and absorption; (iii) indirectly increasing insulin sensitivity; and (iv) nanofiberization by decomposing and modifying the spatial structure of certain natural dietary fibers from plants to inhibit the activity of digestive enzymes to reduce starch digestion. However, the inventors of the present application found in their research that these mechanisms also have corresponding disadvantages. Mechanism (i) causes changes in food texture due to the need to replace a large volume of starch with dietary fiber, affecting people's appetite. Mechanism (ii) has the risk of causing increased gastric burden and indigestion because it may require the simultaneous intake of a large amount of water. Mechanism (iii) relies on long-term regulation of the endocrine system and is not obvious in reducing blood sugar for a single large intake of starch. Mechanism (iv) has special requirements for plant sources and needs to biologically decompose and artificially reconstruct or modify the cellulose from specific plant sources, which is a complex process.

[0009] In particular, for mechanism iv), the biological enzymatic method is complex, the conditions are harsh, and the cost of enzyme reagents is high, which still has difficulties in large-scale production of nanofiber, resulting in low practicality. Although in addition to the biological enzymatic method, nanofiber cellulose can also be prepared by other methods. However, in existing other nanofiber cellulose preparation technologies, strong acids, strong oxidizing agents and other chemical reagents harmful to the human body are generally used for preparation, which has the risk of environmental pollution and is difficult to obtain nanoscale dietary fiber that can be used in the food field. In view of the environmental protection problem, Chinese Patent Application CN202110607105.3 discloses an environmentally friendly preparation and drug liquid recovery method of nanocellulose. The application solves the problem of the very small number of types of nanocellulose by using an environmentally friendly preparation method, proposes to start from plant raw materials, use a 1:2 to 2:1 volume ratio mixed solution system of 17.5 mol / L glacial acetic acid and 30 wt% hydrogen peroxide as a treatment drug liquid, soak the raw materials, and then perform crushing, homogenization, microjet and grinding treatment to obtain nanocellulose, which is used in the fields of degradable plastic reinforcing agent, rheological modifier, thickening agent, etc., and further uses anhydrous copper sulfate to realize drug liquid recovery and recycling. However, the application does not disclose the morphology of the obtained nanocellulose, nor does it mention that food-grade nanocellulose can be obtained by this method or that the nanocellulose obtained by this method can be used in the food field.

[0010] For noodle systems of this kind, when dietary fiber is added to the noodle formulation for the purpose of lowering the GI, in addition to its low GI effect, the three important properties mentioned above, i.e. breakage, cooking loss and mouth feel, need to be considered in particular. Many dietary fibers, when added to noodle formulations, can adversely affect the breakage, cooking loss and mouth feel of the noodle due to their significantly different properties from flour in aqueous dispersion systems. For example, the addition of dietary fiber can result in a significant increase in cooked breakage or natural breakage, or an increase in cooking loss. For another example, the addition of dietary fiber can result in a noodle that is no longer smooth and loses its toughness in mouth feel.

[0011] Therefore, there is still a need for the development of low GI noodles. SUMMARY

[0012] It is an object of the present invention to develop a low GI noodle and a method for preparing the same.

[0013] In one aspect, the present invention provides a low GI noodle comprising:

[0014] nanofiber cell wall extracted from bamboo green, wheat flour, water and edible salt,

[0015] wherein the mass ratio of the nanofiber cell wall to the wheat flour is 0.3% to 0.6%,

[0016] the nanofiber cell wall is edible;

[0017] the cellulose in the nanofiber cell wall has a crystallinity of 80% to 95%;

[0018] the nanofiber cell wall has a one-dimensional feature with a lateral dimension of less than 100 nm and a longitudinal dimension of more than 1 μm;

[0019] the dispersion of the nanofiber cell wall in water has a viscosity of more than 200 Pa•s at a mass concentration of 0.5% of the nanofiber cell wall and remains stable in a temperature range of 5 to 40°C.

[0020] Optionally, the total mass content of the dietary fiber is 0.5% to 1.5%.

[0021] Optionally, the moisture content in the noodle is 10% to 15%.

[0022] Optionally, the low GI noodle comprises:

[0023] 100 parts by weight of wheat flour,

[0024] 0.4 to 0.5 parts by weight of the nanofiber cell wall,

[0025] 1 to 5 parts by weight of edible salt.

[0026] In another aspect, the present application provides a method for preparing the low GI noodles as described above, comprising the following steps:

[0027] (1) mixing the nanoized bamboo fiber cell wall with water and edible salt, then adding wheat flour, stirring uniformly to prepare a dough;

[0028] (2) proofing the dough in a constant temperature and humidity environment, then calendering and cutting to form noodles.

[0029] Optionally, in step (1), the stirring speed is 120 to 200 r / min for 10 to 15 min.

[0030] Optionally, in step (2), the constant temperature and humidity environment for proofing is: constant temperature at 20 to 40℃, constant humidity at 60 to 80%, for 1 to 4 h.

[0031] Optionally, the method further comprises a dehydration treatment after forming the noodles.

[0032] Optionally, the dehydration treatment comprises the following stages:

[0033] First stage: temperature 25℃, humidity 60 to 80%, cycle frequency 40 Hz, time length 10 to 30 min;

[0034] Second stage: temperature 40℃, humidity 75 to 85%, cycle frequency 40 Hz, time length 40 to 60 min;

[0035] Third stage: temperature 45℃, humidity 60 to 70%, cycle frequency 40 Hz, time length 80 to 120 min;

[0036] Fourth stage: temperature 30℃, humidity 50 to 60%, cycle frequency 40 Hz, time length 20 to 40 min.

[0037] Optionally, the nanoized bamboo fiber cell wall in (1) is prepared by the following steps:

[0038] A) adding bamboo green to food-grade anhydrous ethanol, heating to 60 to 80℃, reacting for 24 to 48 h;

[0039] B) adding the mixture obtained in step A) to a solution of food-grade hydrogen peroxide and food-grade glacial acetic acid mixed, reacting at 60 to 80℃ for 24 to 48 h to obtain bleached bamboo fiber cell wall;

[0040] C) using post-treatment including high pressure homogenization to pulverize the bleached bamboo fiber cell wall obtained in step B) to obtain the nano-sized bamboo fiber cell wall.

[0041] The low GI noodles of the present application are beneficial at least in that the unmodified and edible nano-sized bamboo fiber cell wall derived from natural bamboo green is used as a low GI noodle modifier, expanding the use of bamboo and maintaining a high degree of its natural structure; it has a high low GI effect in practice; has excellent low strand breakage rate and low cooking loss rate; and it maintains a smooth and flexible mouthfeel.

[0042] The method for preparing low GI noodles discovered by the present application is beneficial at least in that the bamboo green-based noodles of the present application can be prepared from bamboo green simply, efficiently, with low energy consumption and without pollution. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Transmission electron microscope image of the nano-sized bamboo parenchyma cell wall extracted from bamboo green according to one embodiment of the present application.

[0044] Figure 2 X-ray diffraction curve of the obtained nano-sized bamboo fiber cell wall sample is shown.

[0045] Figure 3 The rheological data curve of the mixed system obtained by adding the low GI noodle modifier with nano-sized bamboo fiber cell wall mass concentration of 0.5%, 1%, 1.5% and cellulose nanocrystals (CNC) obtained by strong acid hydrolysis to starch, respectively, is shown, showing the relationship between viscosity and shear rate.

[0046] Figure 4A / Figure 4B The data curve of the relationship between storage modulus / loss modulus and frequency of the mixed system obtained by adding the low GI noodle modifier with nano-sized bamboo fiber cell wall mass concentration of 0.5%, 1%, 1.5% and cellulose nanocrystals, respectively, to starch is shown.

[0047] Figure 5 The ultraviolet spectrum of the mixed system obtained by adding the low GI noodle modifier with nano-sized bamboo fiber cell wall concentration of 0.5% by weight to amylase and the system without addition is shown.

[0048] Figure 6 The fluorescence spectrum of the mixed system obtained by adding the low GI noodle modifier with nano-sized bamboo fiber cell wall concentration of 0.5% by weight to amylase and the system without addition is shown.

[0049] Figure 7The results show the content of rapidly digestible starch, slowly digestible starch, and resistant starch obtained by adding low-GI noodle improvers containing nano-sized bamboo fiber cell walls at concentrations of 0.5%, 1%, and 1.5% and cellulose nanocrystals obtained by strong acid hydrolysis to starch, respectively.

[0050] Figure 8 The results of cytotoxicity experiments using the low-GI noodle modifier are shown.

[0051] Figure 9 The test reports for noodles according to an embodiment of the present invention are shown. Detailed Implementation

[0052] In response to the technical problems existing in related technologies, the inventors of this invention have developed a low-GI noodle, which contains nano-sized bamboo fiber cell walls extracted from bamboo shoots with specific morphology and properties as a low-GI noodle modifier.

[0053] For diabetic patients, a core issue in blood sugar control is how to rationally manage the glycemic index (GI) through meals. When attempting to improve noodles by adding dietary fiber, ideally, the fiber should remain in its natural state, effectively controlling the GI curve after meals without burdening the digestive system or negatively impacting the smooth and chewy texture of the noodles. Furthermore, as a noodle improver, it should possess good storage stability and high activity during use, and be easy to apply during noodle processing. In particular, the resulting noodles should have the lowest possible breakage rate and cooking loss.

[0054] The inventors of this invention, through research, discovered the use of processed bamboo fiber cell walls extracted from bamboo shoots as a low-GI noodle improver. These bamboo fiber cell walls are nano-sized while retaining some of their natural structure, providing better low-GI functionality on top of conventional dietary fiber without burdening the digestive system, and offering the same or better texture. This low-GI noodle improver combines good storage stability with high activity during use and is easy to apply during noodle processing. In particular, noodles containing this improver exhibit excellent low breakage and cooking loss rates.

[0055] Bamboo is an abundant plant resource in my country and a forestry economic crop. Based on its intended use, it can be mainly divided into bamboo for shoots, bamboo for timber, bamboo for both shoots and timber, and ecological bamboo. Currently, the edible uses of bamboo are primarily limited to bamboo shoots, and the development of food uses beyond bamboo shoots is still largely unexplored.

[0056] Bamboo fiber cells, found in bamboo shoots, are one of the basic building blocks of bamboo. These cells are primarily composed of cell walls and the cytoplasm contained within them. The cell walls mainly contain cellulose, hemicellulose, and lignin, and also contain inorganic matter (ash) and other extracts. Compared to the cell walls of woody products such as timber, unprocessed bamboo fiber cell walls have a higher content of silica (inorganic matter) and a higher content of waxes in their extracts.

[0057] In this invention, the term "nanosized bamboo fiber cell wall" refers to a bamboo fiber cell wall that has been nano-treated, with at least one dimension having a scale in the nanoscale range, while retaining at least part of the natural structure of the bamboo fiber cell wall.

[0058] The term "low-GI noodle improver" refers to a class of functional noodle additives that significantly reduce the glycemic index (GI) of food by adjusting the physical structure, chemical composition, or digestible properties of noodles. Its core objective is to promote a gradual rise in postprandial blood glucose levels.

[0059] The terms "rapidly digestible starch," "slowly digestible starch," and "resistant starch" generally refer to the classification of starches into three categories based on their digestion speed and absorbability in the small intestine: rapidly digestible starch is quickly broken down and absorbed by the small intestine, leading to a rapid rise in blood sugar (such as white bread and cooked potatoes); slowly digestible starch is completely digested but at a slower rate, providing sustained energy and resulting in a stable rise in blood sugar (such as whole wheat bread and oats); and resistant starch is not digested and absorbed by the small intestine at all, but directly enters the large intestine where it is fermented by gut microbiota, does not raise blood sugar, has prebiotic effects, and can improve gut health and metabolism (such as cold rice, raw bananas, and beans).

[0060] Compared with existing cellulose-based dietary fibers in related technologies, the nano-sized bamboo fiber cell wall proposed in this invention, as a low-GI noodle improver, can not only provide the same or better blood sugar control effect, but also provide low breakage rate, low cooking loss rate, and maintain or even improve the texture of noodles.

[0061] This invention provides a low-GI noodle, comprising:

[0062] Nanoscale bamboo fiber cell walls extracted from bamboo shoots, wheat flour, water, and edible salt.

[0063] The mass ratio of nano-sized bamboo fiber cell walls to wheat flour is 0.3% to 0.6%.

[0064] The nano-sized bamboo fiber cell walls are edible;

[0065] The cellulose in the cell wall of the nano-sized bamboo fiber has a crystallinity of 80% to 95%.

[0066] The nano-sized bamboo fiber cell wall has a one-dimensional feature, with a transverse dimension of less than 100 nm and a longitudinal dimension of more than 1 μm;

[0067] The dispersion of the nano-sized bamboo fiber cell wall in water has a viscosity of over 200 Pa•s when the mass concentration of the nano-sized bamboo fiber cell wall is 0.5%, and remains stable in a temperature range of 5 to 40°C.

[0068] The term "noodles" has its well-known meaning in the food industry. The nano-sized bamboo fiber cell walls of this invention are particularly suitable as a low-GI noodle modifier because they have a controlling effect on starch digestion and thus reduce postprandial blood glucose elevation.

[0069] Noodles are a flour product. Flour is wheat flour. As a staple food with a particularly high starch content, and a large proportion of which is rapidly digestible starch, noodles especially require the addition of low-GI noodle improvers. Moreover, the texture and taste of noodles are very sensitive to changes caused by the addition of dietary fiber.

[0070] The low-GI noodles of this invention contain four basic ingredients. Wheat flour, water, and salt are the basic ingredients of ordinary noodles. Any conventional variety of wheat flour can be used. The water is preferably purified water.

[0071] The noodles of this invention also contain special nano-sized bamboo fiber cell walls as a low-GI noodle improver, which provides low-GI characteristics while reducing breakage rate and cooking loss rate and maintaining or improving texture.

[0072] The main component of bamboo fiber cell walls is cellulose, and it also contains hemicellulose and lignin. Correspondingly, nano-sized bamboo fiber cell walls are also a type of cellulose product. Compared to other types of cellulose products, one characteristic of the nano-sized bamboo fiber cell walls extracted from bamboo shoots in this invention is that they consist of bamboo fiber cell walls derived from natural bamboo shoots, rather than artificially synthesized or modified products. They are nano-fragments of bamboo fiber cell walls with most of the lignin and some hemicellulose removed, retaining some of the microstructural characteristics of natural bamboo fiber cell walls, such as their thickness range and the arrangement of cellulose fibers, without reorganization or modification of the fibers. A second characteristic of the nano-sized bamboo fiber cell walls of this invention is that they are edible and can be prepared from low-cost natural bamboo sources using simple, pollution-free methods, thus allowing for economical and safe use as a noodle improver. A third characteristic of the nano-sized bamboo fiber cell walls of this invention is their high crystallinity, which gives them high mechanical stability, chemical stability, biodegradability stability, and thermal stability, as well as low hygroscopicity in air, resulting in high long-term storage stability, which is beneficial for storage, transportation, and use as an independent low-GI improver. The fourth characteristic of the nano-sized bamboo fiber cell wall of this invention is its one-dimensional nature and high aspect ratio, which allows it to exhibit good activity and performance during use, easily interacting with flour and facilitating gel formation with low water content. This, independent of any theory, may explain the low breakage rate, low cooking loss rate, and consistent texture of the noodles produced by this invention. The fifth characteristic of the nano-sized bamboo fiber cell wall of this invention is its high viscosity when dispersed in water at low doses, further improving the processability, properties, and texture of the noodles. The sixth characteristic of the nano-sized bamboo fiber cell wall of this invention is its good thermal stability after dispersion, which is beneficial for practical applications in noodle processing. The seventh characteristic of the nano-sized bamboo fiber cell wall of this invention is its enhanced ability to convert rapidly digestible starch and slowly digestible starch into resistant starch, providing better low-GI performance.

[0073] Practical low-GI noodle modifiers need to meet a variety of requirements in order to provide more benefits or reduce adverse effects on the resulting noodles and noodle preparation process while fully leveraging the glycemic control mechanism, achieving a balance among various desired properties.

[0074] Cellulose includes natural cellulose and synthetic, recombinant, or modified cellulose. For example, the nano-sized burdock functional dietary fiber mentioned earlier belongs to the latter. It involves enzymatic decomposition of the insoluble dietary fiber in burdock, altering its spatial structure. Synthetic, recombinant, or modified fibers can achieve specific functions. However, in the food industry, consumers generally prefer purely natural products or products that are not heavily processed and are close to their natural state, even at the cost of some functionality. Therefore, recombinant or modified non-natural dietary fibers often fail to meet consumer demands. The nano-sized bamboo fiber cell wall of this invention does not decompose, alter, recombin, or modify the fibers in the natural cell wall, thus retaining at least part of the microstructure of the natural bamboo fiber cell wall, more closely resembling the natural state of the raw material, while providing sufficient sugar control functionality, meeting consumer demand for natural or near-natural products.

[0075] This invention not only preserves the natural properties of bamboo fiber cell walls but also nanoscales them without introducing toxic or harmful substances, ensuring the edibility of the nanoscaled bamboo fiber cell walls. The nanoscaled bamboo fiber cell walls of this invention can be prepared from low-value bamboo raw materials using a process that is environmentally friendly, energy-efficient, and simple, offering significant cost advantages.

[0076] In addition to its low-GI functionality, a low-GI noodle improver should possess high stability before being added to the noodle system, and should not easily deteriorate or become ineffective due to environmental factors such as stress during transportation, moisture absorption from the air, or heat during storage. This invention selects a low-GI noodle improver with highly crystalline nano-sized bamboo fiber cell walls, and its product exhibits long-term shelf stability.

[0077] However, high crystallinity can lead to a potential decrease in activity during use. This invention addresses this issue by using nano-sized bamboo fiber cell walls with one-dimensional characteristics, a high aspect ratio, and a lateral dimension below 100 nm. Compared to other granular products, this type of nano-sized bamboo fiber cell wall, when added to a solvent such as water, exhibits a high specific surface area due to its high aspect ratio, allowing it to quickly bind with water and fully activate, rapidly exerting its blood sugar control mechanism. Therefore, its blood sugar control effect is not reduced by high crystallinity. The high aspect ratio also makes its one-dimensional fiber characteristics more pronounced, potentially leading to curling or entanglement during use, which is beneficial for gel formation and reduces the burden on the digestive system. Without relying on any theory, this type of nano-sized bamboo fiber cell wall also improves the breakage performance, cooking loss rate, and texture of noodle systems.

[0078] The nano-sized bamboo fiber cell walls used in this invention can maintain high viscosity even at high water content. This is beneficial for improving the processability, properties, and texture of the noodle system.

[0079] The nano-sized bamboo fiber cell walls used in this invention can maintain good stability in aqueous dispersion systems at room temperature, which is a significant advantage for actual noodle production, as it allows for more flexible requirements on noodle production time and temperature. For example, it can be easily mixed evenly with water at normal room temperature, and then mixed with flour or other materials for dough kneading.

[0080] Of particular note is that when the nano-sized bamboo fiber cell wall selected in this invention is added to the noodle system, it not only exerts the aforementioned sugar control mechanisms (i) to (iv), but also performs particularly well in reducing rapidly digested starch, slowly digesting starch, and increasing resistant starch, thereby further improving the sugar control performance.

[0081] Of particular note among the aforementioned advantages is that the noodles of this invention, by incorporating nano-sized bamboo fiber cell walls, not only achieve excellent low-GI properties but also reduce breakage rate and cooking loss rate while maintaining the noodle's texture. The noodles of this invention achieve a near-zero natural breakage rate and a cooking breakage rate as low as zero. The noodles of this invention also have a very low cooking loss rate. Furthermore, the noodles of this invention maintain their texture. Compared to noodles with the same amount of, for example, cellulose nanocrystals (CNC) obtained through strong acid hydrolysis, which have a higher breakage rate and a noticeably rougher texture and lack of elasticity, the noodles of this invention exhibit significantly lower breakage and cooking loss rates, and a better texture.

[0082] In summary, this invention selects nano-sized bamboo fiber cell walls with specific sources, crystallinity, morphology, and water dispersibility characteristics as a low-GI noodle improver, thereby achieving low-GI improvement of noodles and realizing comprehensive and excellent noodle performance that meets multiple requirements.

[0083] The nano-sized bamboo fiber cell wall of this invention is edible. It is obtained from bamboo fiber cells of natural bamboo shoots using the preparation method described later. This preparation method does not decompose, alter, reorganize, or modify the fibers of the bamboo fiber cell wall itself. No toxic or harmful substances are introduced in this preparation method, ensuring food safety.

[0084] The cellulose in the cell walls of nano-sized bamboo fibers has a crystallinity of 80% to 95%. Preferably, the crystallinity is in the range of 90% to 95%. If the crystallinity is too low, the shelf stability may be poor. If the crystallinity is too high, it may affect its activity during use.

[0085] Nanoscaled bamboo fiber cell walls possess a one-dimensional characteristic, clearly distinguishing them from nanoparticles with granular, spherical / ellipsoidal, or two-dimensional sheet-like shapes. The one-dimensional characteristic refers to the fact that its length dimension is significantly larger than its dimensions in the other two directions. The aspect ratio is in the range of 10 to 400, more preferably 10 to 50, and even more preferably 20 to 50. Its lateral dimension is less than 100 nm, and its longitudinal dimension is greater than 1 μm. Preferably, the lateral dimension is 5 to 60 nm. Preferably, the longitudinal dimension is 1 to 10 μm. The lateral dimension refers to the largest scale in the direction perpendicular to the length direction of the one-dimensional characteristic. For example, the nanoscaled bamboo fiber cell wall can be rod-shaped, in which case the lateral dimension is the diameter of the rod. For example, the nanoscaled bamboo fiber cell wall can also be narrow strip-shaped, in which case the lateral dimension is the width of the strip. If the aspect ratio is too low, the nanoscaled bamboo fiber cell wall will have insufficient activity and poor gelation performance during use. If the aspect ratio is too high, the preparation difficulty will be greater, increasing the cost.

[0086] The dispersion of nano-sized bamboo fiber cell walls in water has a viscosity of 200 Pa•s or higher, more preferably 2000 Pa•s or higher, and even more preferably a viscosity range of 4000 to 5000 Pa•s, when the mass concentration of nano-sized bamboo fiber cell walls is 0.5%. This viscosity reflects the stability of the system. Poor viscosity may affect the texture of noodles. Furthermore, excessively low viscosity may be detrimental to noodle processing and shaping.

[0087] The dispersion of nano-sized bamboo fiber cell walls in water remains stable within a temperature range of 5 to 40°C. Stability is defined as the dispersion system exhibiting no significant change in stability for more than 24 hours, preferably more than 48 hours. This makes it suitable for noodle processing at room temperature.

[0088] In one implementation, the total mass content of dietary fiber in the noodles is 0.5% to 1.5%. Besides nano-sized bamboo fiber cell walls, which are a type of cellulose dietary fiber, other types of dietary fiber can also be added to the noodles. The total mass of dietary fiber should not be too high, otherwise it may affect the texture of the noodles.

[0089] In one embodiment, the noodles have a moisture content of 10 to 15%. Noodles with this moisture content can be stored at room temperature for a longer period of time without requiring an excessively long cooking time.

[0090] In one embodiment, the low-GI noodles comprise:

[0091] 100 parts by weight of wheat flour

[0092] 0.4 to 0.5 parts by weight of the nano-sized bamboo fiber cell wall,

[0093] 1 to 5 parts by weight of table salt.

[0094] This formula yields noodles with the best breakage rate when cooked. The moisture content of the noodles can vary depending on whether dehydration is performed. Dehydration is a common practice in the noodle industry. Typically, fresh noodles, such as handmade noodles or commercially available fresh noodles, have a total moisture content of about 30% to 35%; semi-dried noodles, such as some ramen or udon noodles, have a total moisture content of about 20% to 25%; and dried noodles typically have a total moisture content of less than 15%, such as dried noodles which should have a moisture content of less than 14.5%. Compared to undehydrated noodles, dehydrated noodles have a longer shelf life and absorb more water during cooking. However, regardless of whether dehydration is performed, noodles produced with this formula have a low breakage rate when cooked.

[0095] In one embodiment, the cells of the nano-sized bamboo fiber cell walls are selected from natural bamboo, particularly moso bamboo. There are some difficulties in preparing nano-sized bamboo fiber cell walls using natural bamboo shoots as raw materials. However, the preparation method of the present invention can overcome these difficulties.

[0096] In one embodiment, the present invention provides a low-GI noodle improver comprising nano-sized bamboo fiber cell walls having the aforementioned characteristics. This low-GI noodle improver possesses the aforementioned beneficial properties. The low-GI noodle improver may consist solely of nano-sized bamboo fiber cell walls, such as nano-sized bamboo fiber cell wall powder, or may contain other components, as long as these components do not degrade the overall performance of the low-GI noodle improver. For example, it may contain water.

[0097] In one embodiment, the low-GI noodle improver is a dispersion of the nano-sized bamboo fiber cell wall in water at a mass concentration of 0.1% to 3%, preferably 0.3% to 2.5%, more preferably 0.5% to 2%. This dispersion allows for sufficient activation of the nano-sized bamboo fiber cell wall powder while maintaining dispersion stability for use in noodle preparation processes.

[0098] In one embodiment, the present invention provides a method for preparing the low-GI noodle improver of the present invention, the method comprising preparing the nano-sized bamboo fiber cell wall by the following steps:

[0099] A) Add natural bamboo cell source to noodle-grade anhydrous ethanol, heat to 60 to 80°C, and react for 24 to 48 h;

[0100] B) Add the mixture obtained in step A) to a solution of noodle-grade hydrogen peroxide and noodle-grade glacial acetic acid, and react at 60 to 80°C for 24 to 48 h to obtain bleached bamboo fiber cell walls.

[0101] C) The bleached bamboo fiber cell wall obtained in step B) is pulverized using a post-treatment including high-pressure homogenization to obtain the nano-sized bamboo fiber cell wall.

[0102] Regardless of any theoretical basis, step A) prior to bleaching is crucial in the preparation method of this invention. It promotes the precipitation of the cell walls of the bamboo fiber cells from the natural bamboo shoots, while simultaneously removing some ethanol-soluble substances from the bamboo fiber cells that might interfere with the subsequent bleaching process. By implementing step A), compared to the aforementioned Chinese patent application CN202110607105.3, the concentration of glacial acetic acid used can be reduced to approximately 60% to 80%, and the concentration of hydrogen peroxide can be reduced to below 30%, thus simplifying the process requirements.

[0103] In particular, step A) of the preparation method of the present invention can help overcome the difficulty of preparing nano-sized bamboo fiber cell walls from bamboo fiber cells in bamboo shoots. Compared with wood raw materials, bamboo raw materials contain a relatively high amount of wax in their cell walls. The presence of wax hinders the reaction of hydrogen peroxide and glacial acetic acid with the cell source on the one hand, and easily remains in the final product after bleaching and pulverization, potentially affecting the properties of the noodles. For bamboo shoot raw materials, the present invention effectively dissolves the wax by pre-treating with anhydrous ethanol, reducing its adverse effects in the bleaching step, and also promoting the precipitation of cellulose from natural plants. In addition, it also reduces the residual wax in the noodle improver, reducing the adverse effects on the final noodle product.

[0104] In one embodiment, the present invention provides noodles comprising the low-GI noodle improver of the present invention. The low-GI noodle improver may be a dispersion of nano-sized bamboo fiber cell walls in water at a mass concentration of 0.1% to 3%, preferably 0.3% to 2.5%, more preferably 0.5% to 2%. Furthermore, in the starch-like system, the mass ratio of the low-GI noodle improver to flour may be in the range of 1:1 to 1:5, preferably 1:2 to 1:4. The selected range allows for sufficient control of the glycemic index after noodle consumption while maintaining noodle properties such as texture and stability.

[0105] This invention provides a method for preparing the low-GI noodles of this invention, comprising the following steps:

[0106] (1) First, mix the nano-sized bamboo fiber cell wall with water and edible salt, then add wheat flour, stir evenly, and make dough;

[0107] (2) The dough is rested in a constant temperature and humidity environment, then rolled and cut into strips to form noodles.

[0108] After preparing the nano-sized bamboo fiber cell walls, noodles can be made using conventional mixing and stirring methods. This invention chooses to first mix the nano-sized bamboo fiber cell walls with water and salt before adding flour. The advantage of this method is that it makes it easier for the nano-sized bamboo fiber cell walls to exert their activity. Typically, the mixing operation is carried out in a mixer. When preparing fresh noodles, to facilitate kneading, the total water content in the mixture can be approximately 30% to 40%, equivalent to approximately 40 to 70 parts water for 100 parts flour.

[0109] Preferably, in step (1), the stirring speed is 120 to 200 r / min, more preferably 140 to 160 r / min, such as about 150 r / min, for 10 to 15 minutes. Such stirring can fully mix the noodle ingredients and form a fully expanded and evenly distributed gluten network in the raw material mixture of the present invention, which is beneficial to forming noodles that are tough, resistant to overcooking, and have a good taste.

[0110] Resting the dough allows for even distribution of moisture and relaxes the gluten network, improving noodle processing performance. Preferably, in step (2), the resting environment is a constant temperature and humidity environment: a constant temperature between 20°C and 40°C, a constant humidity between 60% and 80%, and a resting time of 1 to 4 hours. Under this constant temperature and humidity environment and resting time, the dough becomes easier to roll.

[0111] Preferably, the method of the present invention further includes a dehydration process after noodle formation. The dried noodles obtained after dehydration are easy to store. The dried noodles require a slightly longer cooking time, but their breakage rate and texture are essentially unaffected.

[0112] Preferably, the dehydration process includes the following stages:

[0113] Phase 1: Temperature 25℃, humidity 60% to 80%, circulation frequency 40Hz, duration 10 to 30 minutes;

[0114] Second stage: Temperature 40℃, humidity 75% to 85%, circulation frequency 40Hz, duration 40 to 60 minutes;

[0115] Third stage: Temperature 45℃, humidity 60% to 70%, circulation frequency 40Hz, duration 80 to 120min;

[0116] Fourth stage: Temperature 30℃, humidity 50% to 60%, cycle frequency 40Hz, duration 20 to 40 minutes.

[0117] The circulation frequency refers to the operating frequency of the airflow or dehumidification system in conventional dehydration equipment in this field. The advantage of this staged dehydration is that it can gradually and evenly remove moisture from the noodles, avoiding surface cracking, deformation, or uneven internal stress caused by excessively rapid drying. This effectively controls the breakage rate of the product and maintains the original shape and texture of the noodles after rehydration.

[0118] Preferably, the nano-sized bamboo fiber cell wall in (1) is prepared by the following steps:

[0119] A) Add bamboo green to food-grade anhydrous ethanol, heat to 60 to 80°C, and react for 24 to 48 hours;

[0120] B) Add the mixture obtained in step A) to a solution of food-grade hydrogen peroxide and food-grade glacial acetic acid, and react at 60 to 80°C for 24 to 48 h to obtain bleached bamboo fiber cell walls.

[0121] C) The bleached bamboo fiber cell wall obtained in step B) is pulverized using a post-treatment including high-pressure homogenization to obtain the nano-sized bamboo fiber cell wall.

[0122] This preparation method can conveniently and efficiently produce nano-sized bamboo fiber cell walls with the desired morphology.

[0123] More preferably, the nano-sized bamboo fiber cell walls have a transverse dimension distribution ranging from 5 to 60 nm, a longitudinal dimension distribution ranging from 1 to 10 μm, and an aspect ratio distribution ranging from 10 to 400, more preferably from 10 to 50, and even more preferably from 20 to 50. Furthermore, preferably, their surface charge distribution ranges from -60 to -10 mV. This surface charge distribution range is beneficial for improving stability.

[0124] The preferred method for preparing nano-sized bamboo fiber cell walls of the present invention can also be referred to as an edible peeling method. The term "edible peeling method" refers to a method for preparing a safe and edible nano-sized bamboo fiber cell wall through treatment with food-grade reagents and mechanical processing, wherein most of the lignin and part of the hemicellulose in the cell wall are "peeled" away, preserving as much of its natural microstructure of cellulose arrangement as possible. In this invention, the food-grade reagents include food-grade anhydrous ethanol, food-grade glacial acetic acid, and food-grade hydrogen peroxide.

[0125] Preferably, before step A), the process may further include: repeatedly soaking commercially available bamboo shoots in deionized water to remove most of the surface salt.

[0126] Preferably, in step A), the mass ratio of bamboo raw material to anhydrous ethanol is 1:3 to 1:15, more preferably 1:5 to 1:10.

[0127] More preferably, the temperature in step A) of the present invention is 75 to 80°C, and the holding time is more preferably 36 to 48 h.

[0128] Preferably, in step B) of the present invention, the concentration of hydrogen peroxide solution is 10% to 30%, more preferably 15% to 25%; the concentration of glacial acetic acid solution is 60% to 80%, and the mass ratio of the two is 1:5 to 1:20; the mass ratio of bamboo raw material to reaction solution is 1:3 to 1:5.

[0129] In step C) of this invention, a post-processing method including high-pressure homogenization is used. The high-pressure homogenization crushing method relies on the pressurization and depressurization process of liquid to complete the material crushing through effects such as shearing, cavitation, and impact. The inventors have discovered that when plant cells are derived from herbaceous plants, they contain a relatively high content of silica, a high-hardness substance, compared to woody plant sources. Mechanical crushing using methods such as high-speed rotating cutters may result in rapid cutter wear, leading to reduced processing efficiency and potentially introducing impurity particles. High-pressure homogenization avoids these drawbacks and is therefore particularly suitable for preparing nano-sized bamboo fiber cell walls from herbaceous plants. Preferably, the mechanical pulverization of the bleached bamboo fiber cell wall dispersion includes any one or more combinations of a high-pressure homogenizer, a cell ultrasonic disruptor, and a pulper, with a pulverization time of 1 to 5 hours. Preferably, the mass concentration of the bamboo fiber cell wall dispersion in water is 0.5% to 2%. Preferably, the high-pressure homogenization process can be carried out for 2 to 5 hours.

[0130] The purpose of the above preparation method is to enable the nano-sized bamboo fiber cell walls extracted from bamboo to have the required high crystallinity, high aspect ratio and excellent mechanical and thermal stability, so as to realize the use of the present invention as a low-GI noodle improver.

[0131] The method of this invention extracts nano-sized bamboo fiber cell walls from bamboo shoots without adding toxic or harmful solvents, resulting in minimal environmental pollution, low energy consumption, a simple and efficient peeling process, and food safety features.

[0132] The low-GI noodle improver of the present invention uses nano-sized bamboo fiber cell walls with special properties. When used in noodle systems, especially starch-like substances, it also has the function of reducing rapidly digested starch, slowing down the digestion of starch, and increasing resistant starch.

[0133] In this invention, the process of combining low-GI noodle improvers with starch and characterizing their properties may include the following steps:

[0134] Step a): Add a certain amount of deionized water or remove a certain amount of water to the prepared nano-sized bamboo fiber cell wall aqueous dispersion to adjust the mass concentration, so as to prepare a nano-sized bamboo fiber cell wall aqueous dispersion with a mass concentration of 0.1 to 3%, preferably 0.3 to 2.5%, more preferably 0.5 to 2%;

[0135] Step b): Add the nano-sized bamboo fiber cell wall aqueous dispersion obtained in step a) to starch. The nano-sized bamboo fiber cell wall aqueous dispersion and starch are compounded in a mass ratio of 1:1 to 1:5, preferably 1:2 to 1:4. Then, the mixture is uniformly mixed and dispersed by mechanical means, and then left to stand in a freezer for 30 to 60 minutes.

[0136] Step c): Take out 5 to 10 mL or 5 to 10 g of the well-dispersed solution obtained in step b) and place it in a glass beaker. Perform rheological property testing on the material using a viscosity measurement method. For example, a Waters HR20 rheometer from TA Instruments (USA) can be used. Use a parallel plate with a diameter of 60 mm and measure the shear rate from 0.01 to 100 s⁻¹ at 8°C. -1 The change in solution viscosity and the frequency from 1 to 100 rad / s -1 Changes in the storage modulus and loss modulus of the solution.

[0137] The mechanical stirring described in step b) above can be performed using a magnetic stirrer, ultrasonic stirrer, PTFE stirrer, or cell disruptor, preferably a magnetic stirrer or cell disruptor, and more preferably a cell disruptor; the mechanical stirring rate range is 1500 to 3000 r / min. -1 Stir for 2 to 15 minutes, and let stand in the refrigerator for 10 to 15 minutes.

[0138] In this invention, nano-sized bamboo fiber cell walls are added to starch, forming a dense network structure with good stability between the nano-sized bamboo fiber cell walls and starch, which can exhibit one or more of the following effects:

[0139] i) Adding the low-GI noodle improver to the desired starch system results in a more compact starch system structure;

[0140] ii) Adding the low-GI noodle improver to the desired starch-like system significantly improves viscosity and storage modulus;

[0141] iii) After adding the low-GI noodle improver to the starch-like system and gelatinizing it, an in vitro simulated digestion experiment was conducted. As the concentration of nano-sized bamboo fiber cell walls extracted from bamboo increased, the content of rapidly digestible starch and slowly digestible starch decreased, while the content of resistant starch increased.

[0142] When low-GI noodle improvers are added to a liquid system of porcine pancreatic amylase, they can interact with amylase and reduce its activity.

[0143] To further understand the present invention, the application and corresponding inhibitory effect of nano-sized bamboo fiber cell walls in inhibiting starch digestion are further illustrated below with reference to embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0144] Example

[0145] In this embodiment, bamboo shoots were used as a natural plant source to provide the cell walls of bamboo fibers, purchased from a bamboo product store on Taobao. The raw material appeared as follows. Figure 1 As shown.

[0146] The characterization experiments of the target performance parameters in the embodiments all use methods commonly used in the art.

[0147] Example 1: Preparation of Nanoscale Bamboo Fiber Cell Wall

[0148] Nanoscale bamboo fiber cell walls were prepared using the following steps.

[0149] First, soak 1000g of bamboo leaves in deionized water multiple times to remove most of the salt from the surface.

[0150] Subsequently, the desalted bamboo shoots were added to food-grade anhydrous ethanol and reacted in a reaction vessel at 80°C for 12 hours to promote the bleachability of the bamboo shoot cell walls. The ratio of the two was 1:6.

[0151] After the bamboo leaves were washed with deionized water, they were bleached in a pre-prepared mixed solution of food-grade hydrogen peroxide aqueous solution and food-grade glacial acetic acid aqueous solution at a ratio of 1:4. The concentration of the hydrogen peroxide aqueous solution was 20%, the concentration of the glacial acetic acid aqueous solution was 60%, the mass ratio of the two solutions was 1:10, the reaction time was 24 h, and the reaction temperature was 60℃.

[0152] After the bleaching step, the mixture was allowed to stand and then separated into layers: the upper layer was a floating slurry, the lower layer was a liquid, and the bottom layer was sediment. The upper slurry was separated and washed with water, an appropriate amount of water was added, and then the mixture was pulverized in a pulper for 1 hour, followed by crushing in a high-pressure homogenizer for 120 minutes to obtain a nano-sized bamboo fiber cell wall dispersion, which is a uniformly dispersed, semi-transparent white dispersion.

[0153] Figure 2The X-ray diffraction curve of the obtained nano-sized bamboo fiber cell wall sample is shown. Its characteristic peaks indicate that the main component of the obtained sample is cellulose. The crystallinity of cellulose can be calculated from the X-ray diffraction curve. Repeated preparation experiments showed that the crystallinity of cellulose obtained according to the preparation method of Preparation Example 1 was 80% to 95%.

[0154] Images of nano-sized bamboo fiber cell walls observed under an electron microscope show that they have one-dimensional characteristics, with a lateral dimension of less than 100 nm and a longitudinal dimension of more than 1 μm.

[0155] The rheological properties of the obtained dispersion were tested using a HAAKE MARS 60 rotational rheometer after the concentration was adjusted to 0.5%. Parallel plates with a diameter of 60 mm were used, and shear rates were measured from 0.01 to 100 s⁻¹ at 8°C. -1 The change in solution viscosity and the frequency from 1 to 100 rad / s -1 Changes in the storage modulus and loss modulus of the solution.

[0156] Repeated experiments showed that the aqueous dispersion of the obtained nano-sized bamboo fiber cell wall had a viscosity of more than 200 Pa•s when the mass concentration of nano-sized bamboo fiber cell wall was 0.5%, and remained stable for more than 24 hours in a temperature range of 5 to 40℃.

[0157] Example 2 of preparation of nano-sized bamboo fiber cell walls

[0158] Nanoscale bamboo fiber cell walls were prepared in a manner essentially the same as in Example 1, except that: during the food-grade anhydrous ethanol treatment, the reaction time was 24 h; during the bleaching process, the concentration of hydrogen peroxide aqueous solution was 30%, the concentration of glacial acetic acid aqueous solution was 80%, the volume ratio of the two was 1:20, the reaction time was 48 h, and the reaction temperature was 80 °C; during the pulverization process, the cells were pulverized in a pulper for 2 h, and then crushed in a high-pressure homogenizer for 90 minutes.

[0159] The product was subjected to the aforementioned detection and characterization, and the results were consistent with those of Example 1, which was used to prepare nano-sized bamboo fiber cell walls.

[0160] Example 1 of the performance of noodle improver

[0161] The product obtained from Example 1 of the preparation of nano-sized bamboo fiber cell walls was used as a low-GI noodle improver in an experiment added to a starch-like system. Before addition, the content ratio of the low-GI noodle improver in the dispersion was adjusted. Specifically, the product from Example 1 of the preparation of nano-sized bamboo fiber cell walls was dried, weighed, and its solid content was calculated. Based on the calculation result, a certain amount of water was added or evaporated to obtain an aqueous dispersion with a predetermined mass concentration of nano-sized bamboo fiber cell walls. Aqueous dispersions of nano-sized bamboo fiber cell walls with mass concentrations of 0.5%, 1%, and 1.5% were prepared in this manner as low-GI noodle improver samples.

[0162] The uniformly dispersed mixture obtained after gelatinization was allowed to stand in a freezer for 30 to 60 minutes. 10 g of the mixture was then placed in a glass beaker, and its rheological properties were tested using a HAAKE MARS 60 rotational rheometer. A parallel plate with a diameter of 60 mm was used, and shear rates from 0.01 to 100 s⁻¹ were measured at 8°C. -1 The change in solution viscosity and the frequency from 1 to 100 rads -1 Changes in the storage modulus and loss modulus of the solution. Figure 3 , Figure 4A and Figure 4B The measurement results are shown.

[0163] Figure 3 , Figure 4A and Figure 4B The rheological data curves of the mixtures obtained by adding each low-GI noodle improver sample to starch at a mass ratio of 1:2 are shown, illustrating the relationship between viscosity and shear rate, as well as the relationship between storage modulus and loss modulus and frequency.

[0164] Example 2 of noodle improver performance

[0165] The low-GI noodle improver sample was prepared using the same method as in Example 1 of the noodle improver performance test.

[0166] A low-GI noodle improver sample with a nano-sized bamboo fiber cell wall concentration of 0.5% and porcine pancreatic amylase were mixed at a mass ratio of 10:1. The mixture was stirred at room temperature and allowed to stand at room temperature for 20 minutes after stirring until homogeneous, resulting in a homogeneous mixed solution system.

[0167] Figure 5 The ultraviolet spectrum of this mixture, measured using a SOLID 3700 ultraviolet-visible-near-infrared spectrophotometer, is shown.

[0168] Figure 6 The fluorescence spectrum of this mixture, measured using an XRF-1800 X-ray fluorescence spectrometer, is shown.

[0169] Figure 5 , 6 Microscopically, it was shown that the nano-sized bamboo fiber cell walls reduced enzyme activity, thereby inhibiting digestion.

[0170] One mL of the supernatant from the obtained mixed solution system was placed in a glass beaker and measured using an ELISA reader to calculate the porcine pancreatic amylase activity. The comparison with the control group showed a decrease in porcine pancreatic amylase activity.

[0171] Without relying on any theory, the low-GI noodle improver of this invention can inhibit the activity of α-amylase and hinder starch digestion through physicochemical interactions and steric hindrance effects, achieving a low-GI effect. Specifically, the hydroxyl and carboxyl functional groups on the surface of the nano-sized bamboo fiber cell wall in the low-GI noodle improver can directly adsorb α-amylase molecules through electrostatic interactions and hydrogen bonds, resulting in the masking of the enzyme's active site or a conformational change. In addition to inhibiting the activation of amylase molecules, the three-dimensional network structure formed by the nano-sized bamboo fiber cell wall in the starch matrix can physically block the contact between α-amylase and starch molecules, significantly reducing the enzymatic hydrolysis efficiency. Furthermore, the nano-sized fiber cell wall can also affect the gelatinization and retrogradation properties of starch by preferentially binding with amylose, further reducing the exposure of enzymatic hydrolysis sites. These synergistic effects ultimately lead to a significant reduction in the rate and extent of starch digestion. In particular, the nano-sized bamboo fiber cell wall of this invention may have a better effect on inhibiting amylase than cellulose nanocrystals obtained by conventional strong acid hydrolysis due to the retention of some natural cell wall structure and specific morphology.

[0172] Example 3 of noodle improver performance

[0173] Each low-GI noodle improver sample was prepared using the same method as in Example 1 of noodle improver performance and then gelatinized with starch.

[0174] Figure 7 The contents of rapidly digestible starch, slowly digestible starch, and resistant starch in these mixtures are shown, as measured using an ST-360 microplate reader.

[0175] Figure 7 This demonstrates that adding a low-GI noodle improver reduces the content of rapidly digestible and slowly digestible starches while increasing the content of resistant starches, thus achieving a low-GI effect.

[0176] When the low-GI noodle improver of the present invention is added to starch, due to the high specific surface area and network structure formed by the nanoscale and one-dimensional characteristics of its nano-sized bamboo fiber cell wall, it can effectively reduce the proportion of rapidly digestible starch and slowly digestible starch in starch, increase the proportion of resistant starch, and further improve the low-GI effect.

[0177] Noodle improver performance example 4

[0178] Cytotoxicity experiments were conducted using a low-GI noodle modifier on gastric epithelial cells. The control group consisted of normally cultured cells without the low-GI noodle modifier. The results showed that both groups exhibited the same cell activity, demonstrating that the low-GI noodle modifier of this invention is non-toxic.

[0179] Figure 8 The experiment showed the cytotoxicity of the low-GI noodle modifier with gastric epithelial cells.

[0180] It can be seen that the cell walls of nano-sized bamboo fibers are non-toxic to gastric epithelial cells.

[0181] Comparative Example 1

[0182] This comparative example is the same as Example 1 of the noodle improver performance, except that the nano-sized bamboo fiber cell walls were replaced with cellulose nanocrystals (CNCs) at a mass concentration of 0.5%. The CNCs used in this comparative example were obtained from wood using conventional methods through strong acid hydrolysis, retaining only the cellulose crystalline region.

[0183] Figure 3 , Figure 4A , Figure 4B Rheological data obtained from nano-sized bamboo fiber cell walls and cellulose nanocrystals in Example 1 and Comparative Example 1, which are performance examples of noodle improvers.

[0184] Compared to adding cellulose nanocrystals, the addition of the nano-sized bamboo fiber cell wall of this invention results in a system with higher viscosity, storage modulus, and loss modulus. The mixture system of this invention also exhibits better processability.

[0185] Comparative Example 2

[0186] This comparative example is the same as Example 3 of the noodle improver performance, except that the nano-sized bamboo fiber cell wall is replaced with cellulose nanocrystals with a mass concentration of 0.5%.

[0187] Figure 7 The performance of the noodle improver was demonstrated in Example 3 and Comparative Example 2 using nano-sized bamboo fiber cell walls and cellulose nanocrystals at mass concentrations of 0.5%, 1%, and 1.5%, respectively, to obtain the contents of rapidly digestible starch, slowly digestible starch, and resistant starch. Compared with the addition of cellulose nanocrystals, the addition of nano-sized bamboo fiber cell walls resulted in less rapidly digestible starch and slowly digestible starch, and more resistant starch. Furthermore, with increasing concentration, the rapidly digestible starch and slowly digestible starch further decreased, while the resistant starch further increased.

[0188] Comparative Example 3

[0189] The preparation was carried out in the same manner as in Example 1 of the preparation of nano-sized bamboo fiber cell walls, except that the anhydrous ethanol reaction step was not performed.

[0190] The same characterization of the product showed that its hemicellulose and lignin residues were high and its one-dimensional characteristics were poor.

[0191] Noodle preparation example

[0192] Noodles were prepared using the nano-sized bamboo fiber cell walls obtained in Example 1. The specific preparation process is as follows:

[0193] (1) Mix 40 parts of the aqueous dispersion of the nano-sized bamboo fiber cell wall with an amount of 1% by mass with an additional 11 parts of water and 4 parts of edible salt, then add 100 parts of wheat flour, stir evenly, and make dough, wherein the mass ratio of nano-sized bamboo leaf cell wall to wheat flour is 0.4%;

[0194] (2) The dough is rested in a constant temperature and humidity environment, then rolled and cut into strips to form noodles;

[0195] (3) Dehydrate the formed noodles.

[0196] The stirring speed is 200 r / min for 15 min. The conditions for proofing the dough are constant temperature and humidity: constant temperature between 20℃ and 40℃, constant humidity between 60% and 80%, for 1 to 4 hours.

[0197] The dehydration process includes the following stages:

[0198] Phase 1: Temperature 25℃, humidity 80%, cycle frequency 40Hz, duration 30min;

[0199] Second stage: Temperature 40℃, humidity 85%, circulation frequency 40Hz, duration 60min;

[0200] Third stage: Temperature 45℃, humidity 70%, circulation frequency 40Hz, duration 120min;

[0201] Fourth stage: Temperature 30℃, humidity 60%, cycle frequency 40Hz, duration 40min.

[0202] The prepared noodles were subjected to performance tests according to GB 5009.3-2016 "Determination of Moisture in Food", GB 5009.239-2016 "Determination of Acidity in Food", GB 5009.5-2016 "Determination of Protein in Food" and GB / T 40636-2021 "Dried Noodles". The test results are shown in... Figure 9 middle.

[0203] As can be seen, noodles made by adding nano-sized bamboo fiber cell walls to noodle ingredients achieve a low-GI function while fully meeting national standards, and exhibiting excellent performance in several parameters, such as extremely low acidity and low natural breakage rate. Particularly noteworthy is its cooked breakage rate, which can be as low as 0. Furthermore, it retains the characteristic texture of noodles.

[0204] As can be seen, the nano-sized bamboo fiber cell walls obtained in this invention, when added to starch, verify that this material has the effect of inhibiting the increase of glycemic index (GI) through multiple mechanisms. Therefore, it has broad application prospects, especially in the field of low-GI noodles. The nano-sized cell walls extracted from natural plants in this invention, when added to noodle product systems, can not only reduce the glycemic index and obtain low-GI noodles, but also improve the stability and maintain the texture of the noodles. The preparation method is simple, non-toxic, efficient, and environmentally friendly in obtaining the desired nano-sized bamboo fiber cell walls, with anhydrous ethanol treatment improving the preparation effect.

[0205] The above descriptions of specific embodiments and examples are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles and spirit, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A low-GI noodle, characterized in that, It includes: Nanoscale bamboo fiber cell walls extracted from bamboo shoots, wheat flour, water, and edible salt. The mass ratio of nano-sized bamboo fiber cell walls to wheat flour is 0.3% to 0.6%. The nano-sized bamboo fiber cell walls are edible; The cellulose in the cell wall of the nano-sized bamboo fiber has a crystallinity of 80% to 95%. The nano-sized bamboo fiber cell wall has a one-dimensional feature, with a transverse dimension of less than 100 nm and a longitudinal dimension of more than 1 μm; The dispersion of the nano-sized bamboo fiber cell wall in water has a viscosity of over 200 Pa•s when the mass concentration of the nano-sized bamboo fiber cell wall is 0.5%, and remains stable in a temperature range of 5 to 40°C.

2. The low-GI noodles according to claim 1, characterized in that, The total mass content of dietary fiber is 0.5% to 1.5%.

3. The low-GI noodles according to claim 1, characterized in that, The moisture content of the noodles is 10% to 15%.

4. The low-GI noodles according to claim 1, characterized in that, The low-GI noodles contain: 100 parts by weight of wheat flour 0.4 to 0.5 parts by weight of the nano-sized bamboo fiber cell wall, 1 to 5 parts by weight of table salt.

5. A method for preparing low-GI noodles according to claim 1, characterized in that, Includes the following steps: (1) The nano-sized bamboo fiber cell wall is mixed with water and edible salt, and then wheat flour is added and stirred evenly to make dough; (2) The dough is rested in a constant temperature and humidity environment, and then rolled and cut into strips to form noodles.

6. The method according to claim 5, characterized in that, In step (1), the stirring speed is 120 to 200 r / min and lasts for 10 to 15 min.

7. The method according to claim 5, characterized in that, In step (2), the constant temperature and humidity environment of the proofing surface is: the constant temperature is between 20°C and 40°C, the constant humidity is between 60% and 80%, and the time is 1 to 4 hours.

8. The method according to claim 5, characterized in that, The method also includes a dehydration process after the noodles are formed.

9. The method according to claim 8, characterized in that, The dehydration process includes the following stages: Phase 1: Temperature 25℃, humidity 60% to 80%, circulation frequency 40Hz, duration 10 to 30 minutes; Second stage: Temperature 40℃, humidity 75% to 85%, circulation frequency 40Hz, duration 40 to 60 minutes; Third stage: Temperature 45℃, humidity 60% to 70%, circulation frequency 40Hz, duration 80 to 120min; Fourth stage: Temperature 30℃, humidity 50% to 60%, cycle frequency 40Hz, duration 20 to 40 minutes.

10. The method according to claim 5, characterized in that, The nano-sized bamboo fiber cell wall in (1) was prepared by the following steps: A) Add bamboo green to food-grade anhydrous ethanol, heat to 60 to 80°C, and react for 24 to 48 hours; B) Add the mixture obtained in step A) to a solution of food-grade hydrogen peroxide and food-grade glacial acetic acid, and react at 60 to 80°C for 24 to 48 h to obtain bleached bamboo fiber cell walls. C) The bleached bamboo fiber cell wall obtained in step B) is pulverized using a post-treatment including high-pressure homogenization to obtain the nano-sized bamboo fiber cell wall.

Images