Low-GI noodles containing nanocrystallized bamboo leaf cell walls and preparation method of low-GI noodles

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 leaf cell walls, wheat flour, water and edible salt, the mass ratio of the nano bamboo leaf cell walls to the wheat flour is 0.3%-0.6%, and the nano bamboo leaf cell walls are edible; cellulose in the nanocrystallized bamboo leaf cell walls has the crystallinity of 80%-95%; the nanocrystallized bamboo leaf 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 leaf cell walls in the water has the viscosity of 200 Pas or above when the mass concentration of the nanocrystallized bamboo leaf 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 nanoized bamboo leaf cell wall 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, the natural breakage rate and the 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 people with problems in blood sugar, such as diabetic patients, because they have a high glycemic index (GI) and can easily cause rapid postprandial blood glucose rise. Therefore, many studies have been conducted to develop low GI noodles. Adding dietary fiber to noodle formulations 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, a starch-like system, when dietary fiber is added to the noodle formulation for the purpose of low GI, in addition to its low GI effect, the three important properties mentioned above, i.e. breakage rate, cooking loss rate and mouth feel, need to be considered especially. Many dietary fibers, when added to the noodle formulation, due to their significantly different properties from flour in aqueous dispersion system, will have adverse effects on the breakage rate, cooking loss rate and mouth feel of the noodle. For example, after the addition of dietary fiber, the cooked breakage rate or natural breakage rate of the noodle can be significantly increased, or the cooking loss rate can be increased. For another example, after the addition of dietary fiber, the mouth feel of the noodle becomes no longer smooth and loses toughness.

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

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

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

[0014] nano-sized bamboo leaf cell wall, wheat flour, water and edible salt,

[0015] wherein the mass ratio of the nano-sized bamboo leaf cell wall to the wheat flour is 0.3% to 0.6%,

[0016] the nano-sized bamboo leaf cell wall is edible;

[0017] the cellulose in the nano-sized bamboo leaf cell wall has a crystallinity of 80% to 95%;

[0018] the nano-sized bamboo leaf cell wall has a one-dimensional feature, with a lateral size of less than 100 nm and a longitudinal size of more than 1 μm;

[0019] the dispersion of the nano-sized bamboo leaf cell wall in water has a viscosity of more than 200 Pa•s at a mass concentration of 0.5% of the nano-sized bamboo leaf cell wall and remains stable in a temperature range of 5 to 40℃.

[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 nano-sized bamboo leaf 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 leaf cell wall with water and edible salt, then adding wheat flour, stirring uniformly to obtain 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 has a constant temperature of 20 to 40 °C and a constant humidity of 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 °C, humidity 60% to 80%, cycle frequency 40 Hz, time length 10 to 30 min;

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

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

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

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

[0038] A) adding bamboo leaves to food-grade anhydrous ethanol, heating to 60 to 80 °C, and 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 °C for 24 to 48 h to obtain bleached bamboo leaf cell wall;

[0040] C) using post-treatment including high-pressure homogenization to crush the bleached bamboo leaf cell wall obtained in step B) to obtain the nanoized bamboo leaf cell wall.

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

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

[0043] Figure 1 A photo of the raw material of unprocessed bamboo leaf.

[0044] Figure 2 Photos showing different stages of preparation of nanofibrillated bamboo leaf cell wall.

[0045] Figure 3 A scanning electron microscope photo of the raw material of bamboo leaf.

[0046] Figure 4 A X-ray diffraction curve of the obtained nanofibrillated bamboo leaf cell wall sample.

[0047] Figure 5 An image of the nanofibrillated bamboo leaf cell wall showing a piece of one-dimensional features observed under an electron microscope.

[0048] Figure 6 A photo showing the appearance of noodles with added nanofibrillated bamboo leaf cell wall.

[0049] Figure 7 A data curve showing the relationship between viscosity and shear rate of the mixed system obtained by adding low GI noodle modifier with nanofibrillated bamboo leaf cell wall mass concentration of 0.5%, 1%, 1.5% and cellulose nanocrystals (CNC) obtained by strong acid hydrolysis into starch, respectively.

[0050] Figure 8A / Figure 8B A data curve showing the relationship between storage modulus / loss modulus and frequency of the mixed system obtained by adding low GI noodle modifier with nanofibrillated bamboo leaf cell wall mass concentration of 0.5%, 1%, 1.5% and cellulose nanocrystals obtained by strong acid hydrolysis into starch, respectively.

[0051] Figure 9 A UV spectrum of the mixed system obtained by adding low GI noodle modifier with nanofibrillated bamboo leaf cell wall concentration of 0.5% by weight into amylase and the system without addition.

[0052] Figure 10 The fluorescence spectra of the mixed system obtained by adding the low GI noodle modifier with the concentration of 0.5% by weight of the nanoized bamboo leaf cell wall into amylase and the system without addition are shown.

[0053] Figure 11 The contents of rapidly digestible starch, slowly digestible starch and resistant starch obtained by adding the low GI noodle modifier and cellulose nanocrystals obtained by strong acid hydrolysis with the mass concentrations of 0.5%, 1%, 1.5% of the nanoized bamboo leaf cell wall into starch respectively are shown.

[0054] Figure 12 The results of the cytotoxicity experiment of the low GI noodle modifier and gastric epithelial cells are shown.

[0055] Figure 13 The detection reports of the noodles of the embodiments of the present application are shown. DETAILED DESCRIPTION

[0056] In view of the technical problems in the related art, the inventors of the present application have developed a low GI noodle containing the nanoized bamboo leaf cell wall with specific morphology and performance as a low GI noodle modifier.

[0057] For the sugar control of diabetic patients, how to reasonably control the glycemic index (GI, also commonly known as glycemic index) through meals is a core problem. When trying to modify noodles by adding dietary fiber, it is ideal that the dietary fiber is kept in a natural state as much as possible, which can not only control the GI curve after meals, but also does not increase the burden on the stomach and intestines, and does not adversely affect the smooth and flexible taste of the noodles. In addition, as a noodle modifier itself, it also needs to have good storage stability and high activity in use, and is easy to use in the noodle processing process. In particular, the obtained noodles should have as low a noodle breakage rate and cooking loss rate as possible.

[0058] The inventors of the present application have found the use of a processed bamboo leaf cell wall as a dietary fiber low GI noodle modifier. The bamboo leaf cell wall is a nanoized bamboo leaf cell wall that maintains part of the natural structure, which can provide better low GI functionality on the basis of conventional dietary fiber, and does not increase the burden on the stomach and intestines, and can also provide the same or better taste. The low GI noodle modifier has good storage stability and high activity in use, and is easy to use in the noodle processing process. In particular, the noodles containing it have excellent low noodle breakage rate and cooking loss rate.

[0059] Bamboo is a kind of plant resource which is very rich in China. It is a kind of forestry economic crops. According to the purpose of utilization, it can be mainly divided into bamboo shoots, bamboo, bamboo shoots and bamboo, ecological forest bamboo and so on. On the basis of the traditional use of bamboo, new uses are developed to fully utilize and improve the economic value of bamboo. At present, the edible use of bamboo is basically limited to bamboo shoots, and the development of food use other than bamboo shoots is still basically in a blank state.

[0060] Bamboo leaf cell is one of the basic components of bamboo. Bamboo leaf cell is basically composed of cell wall and cytoplasm contained in the cell wall, wherein the cell wall mainly contains cellulose, hemicellulose and lignin, and also contains inorganic matter (ash) and other extracts. Compared with the cell wall of woody products such as wood, the content of inorganic matter silicon dioxide in the cell wall of unprocessed bamboo leaf is higher, and the content of wax in the extract is higher.

[0061] In the present application, the term "nanoized bamboo leaf cell wall" refers to a nanoized bamboo leaf cell wall which has a scale in the nanoscale range in at least one dimension, while still maintaining at least part of the natural structure of the bamboo leaf cell wall.

[0062] The term "low GI noodle modifier" refers to a kind of functional noodle additive which can significantly reduce the glycemic index (GI) of food by adjusting the physical structure, chemical composition or digestion characteristics of noodles. Its core goal is to make the postprandial blood glucose level rise smoothly.

[0063] The terms "fast digestible starch, slow digestible starch, resistant starch" generally refer to three categories of starches according to the speed of digestion and absorbability in the small intestine: fast digestible starch can be rapidly decomposed and absorbed in the small intestine, resulting in rapid increase of blood glucose (such as white bread, cooked potatoes); slow digestible starch will be completely digested but at a slower speed, providing sustained energy and stable blood glucose rise (such as whole wheat bread, oatmeal); resistant starch is not digested and absorbed by the small intestine at all, directly entering the large intestine to be fermented by intestinal flora, not rising blood glucose, having a prebiotic effect, and being able to improve intestinal health and metabolism (such as cold rice, raw bananas, legumes).

[0064] Compared with the existing cellulose dietary fiber in the related art, the nanoized bamboo leaf cell wall as a low GI noodle modifier can not only provide the same or better blood glucose control effect, but also provide low breakage rate, low cooking loss rate and maintain or even improve the taste of noodles.

[0065] The present application provides a low GI noodle, which comprises:

[0066] Nanoized bamboo leaf cell wall, wheat flour, water, edible salt,

[0067] wherein the mass ratio of the nanoized bamboo leaf cell wall to the wheat flour is 0.3 to 0.6%,

[0068] The nanoized bamboo leaf cell wall is edible.

[0069] The cellulose in the nanoized bamboo leaf cell wall has a crystallinity of 80 to 95%.

[0070] The nanoized bamboo leaf 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.

[0071] The dispersion of the nanoized bamboo leaf cell wall in water has a viscosity of more than 200 Pa-s at a mass concentration of 0.5% and remains stable in the temperature range of 5 to 40°C.

[0072] The term "noodle" has its meaning well known in the field of food. The nanoized bamboo leaf cell wall of the present invention is particularly suitable as a low GI noodle modifier because it has a controlling effect on the digestion of starch and thus reduces the postprandial blood sugar rise.

[0073] Noodles are flour products. Flour is wheat flour. Noodles are particularly in need of a low GI noodle modifier because of their high starch content and the large proportion of rapidly digestible starch. Moreover, the properties and mouthfeel of noodles are very sensitive to deterioration due to the addition of dietary fiber.

[0074] The low GI noodle of the present invention comprises four basic ingredients. Among them, wheat flour, water and edible salt are the basic ingredients of ordinary noodles. Any conventional variety of wheat flour can be used. The water is preferably purified water.

[0075] A special nanoized bamboo leaf cell wall is further added to the noodles of the present invention as a low GI noodle modifier, which provides low GI properties while reducing the breakage rate and cooking loss rate and maintaining or improving the mouthfeel.

[0076] The most important component of bamboo leaf cell wall is cellulose, and it also contains hemicellulose and lignin, etc. Accordingly, the nanoized bamboo leaf cell wall is also a kind of cellulose product. Compared with other kinds of cellulose products, one of the features of the nanoized bamboo leaf cell wall of the present application is that it includes bamboo leaf cell wall derived from natural bamboo, rather than artificially synthesized or modified product. It is a nano fragment of bamboo leaf cell wall from which most of lignin and part of hemicellulose are removed, and the microstructure characteristics of the natural bamboo leaf cell wall, such as its thickness range, arrangement of cellulose fibers, etc., can be retained, without reorganization or modification of the fibers. The second feature of the nanoized bamboo leaf cell wall of the present application is that it is edible, and can be prepared from low-cost natural bamboo source by simple and pollution-free means, so that it can be used as a noodle modifier in an economic and safe manner. The third feature of the nanoized bamboo leaf cell wall of the present application is that it has high crystallinity, which makes it have high mechanical stability, chemical stability, biodegradation stability and thermal stability, and low air moisture absorption, and has high long-term storage stability, which is conducive to storage, transportation and use as an independent low-GI modifier. The fourth feature of the nanoized bamboo leaf cell wall of the present application is that it has one-dimensional characteristics and has a high aspect ratio, so that it has good activity when used to exert its performance, is easy to interact with flour, and is conducive to gel formation at a low water content. Without being bound by any theory, this can be the reason why the noodles of the present application have low noodle breakage rate, low cooking loss rate and maintain mouthfeel. The fifth feature of the nanoized bamboo leaf cell wall of the present application is that it has high viscosity when dispersed in water at a low dosage, so that it can also improve the processability, properties and mouthfeel of noodles. The sixth feature of the nanoized bamboo leaf cell wall of the present application is that it has good thermal stability after forming a dispersion, which is conducive to practical application in noodle processing. The seventh feature of the nanoized bamboo leaf cell wall of the present application is that it has stronger ability to convert rapidly digestible starch and slowly digestible starch into resistant starch, and provides better low-GI performance.

[0077] A practical low-GI noodle modifier needs to meet multiple requirements to balance various desired properties on the premise that it fully exerts the blood glucose control mechanism, and also provides more benefits or reduces adverse effects to the prepared noodles and the noodle preparation process.

[0078] Cellulose includes natural cellulose and artificially synthesized, recombined or modified cellulose. For example, the aforementioned nanoized burdock functional dietary fiber belongs to the latter. It biologically decomposes insoluble dietary fiber in burdock and changes its spatial structure. Artificially synthesized, recombined or modified cellulose can achieve special functions. However, in the food field, consumers usually have a preference for pure natural products or products close to the natural state without deep processing, and are willing to sacrifice part of the functionality for this purpose, so recombined or modified non-natural dietary fiber often cannot meet the requirements of consumers. The nanoized bamboo leaf cell wall of the present application does not decompose, change the spatial structure, recombine or modify the fiber in the natural cell wall, can retain at least part of the microstructure of the natural bamboo leaf cell wall, is closer to the natural state of the raw material, and can still provide sufficient glycemic control functionality, meeting the needs of consumers for natural products or products close to the natural state.

[0079] The present application not only retains the natural properties of the bamboo leaf cell wall, but also nanoizes it, and does not introduce toxic / harmful substances during the process, ensuring the edibility of the nanoized bamboo leaf cell wall. The nanoized bamboo leaf cell wall of the present application can be prepared from low-value bamboo raw materials through a process that is small in environmental pollution, low in energy consumption and simple and efficient in flow, having great advantages in cost.

[0080] In addition to the low GI functionality, as a low GI noodle modifier, it should have high stability before being added to the noodle system, and is not prone to deterioration and failure due to environmental factors such as stress during transportation, moisture absorption in the air or heat during storage. The present application selects a low GI noodle modifier with high crystallinity of nanoized bamboo leaf cell wall, which has long-term shelf stability.

[0081] However, high crystallinity can also cause the problem of reduced activity when used. The present application balances this problem by using nanoized bamboo leaf cell wall with one-dimensional characteristics and high aspect ratio and transverse size below 100 nm. Compared with other morphological granular products, this morphological nanoized bamboo leaf cell wall can quickly combine with water and fully activate when added to a solvent such as water due to the high specific surface area formed by its one-dimensional characteristics of high aspect ratio, quickly exerting its blood glucose control mechanism, so its blood glucose control effect is not reduced by high crystallinity. The high aspect ratio also makes its one-dimensional fiber characteristics more obvious, and it is possible to have a curled, entangled or other morphology when used, which is beneficial to the formation of a gel state and the reduction of the burden on the gastrointestinal tract. Without relying on any theory, this morphological nanoized bamboo leaf cell wall is also beneficial to improving the breaking performance, cooking loss rate and mouthfeel of the noodle system.

[0082] The nanoized bamboo leaf cell wall selected by the present application can also maintain a relatively high viscosity at a high water content. This is beneficial to improving the processability and properties and mouthfeel of the noodle system.

[0083] The nanochitinous cell wall used in the present application can also maintain good stability in an aqueous dispersion system at room temperature, which is also a great advantage for actual noodle production, because it can make the time and temperature requirements for noodle production relaxed. For example, it can be conveniently mixed with water uniformly at a general room temperature, and then mixed with flour and the like to perform a dough-making operation.

[0084] In particular, it is worth noting that the nanochitinous cell wall used in the present application, when added to the noodle system, performs particularly well in reducing rapidly digestible starch, slowly digestible starch, and increasing resistant starch on the basis of exerting the aforementioned glycemic control mechanisms (i) to (iv), thereby further improving the glycemic control performance.

[0085] Among the above advantages, it is particularly noteworthy that the noodles of the present application, by adding the nanochitinous cell wall, not only achieve excellent low GI characteristics, but also achieve a reduction in breakage rate and a reduction in cooking loss rate, and maintain the taste of the noodles from deteriorating. The noodles of the present application can achieve a natural breakage rate close to zero and a cooked breakage rate as low as zero. The noodles of the present application also have a very low cooking loss rate. In addition, the noodles of the present application can maintain the taste. Compared with noodles with a higher breakage rate and a noticeable roughness and lack of toughness by adding the same amount of cellulose nanocrystals (CNC) obtained by strong acid hydrolysis, the breakage rate and cooking loss rate of the noodles of the present application are significantly reduced, and the taste is better.

[0086] In summary, the present application selects nanochitinous cell walls with specific sources, crystallinity, morphology, and water dispersion properties as low GI noodle improvers, achieves low GI improvement of noodles, and achieves comprehensive excellent noodle performance that meets multiple requirements.

[0087] The nanochitinous cell wall of the present application is edible. It is made of natural bamboo parenchyma cells and obtained by the preparation method described below. The preparation method does not decompose, change the spatial structure, recombine or modify the fibers of the bamboo leaf cell wall. In the preparation method, no toxic and harmful substances are introduced to ensure food safety.

[0088] The cellulose in the nanochitinous cell wall 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 when used.

[0089] The nanochitinous cell wall has a one-dimensional feature, which is obviously different from the nano-particles with granular, spherical / ellipsoidal, two-dimensional sheet-like shapes. The one-dimensional feature means that the length dimension is much larger than the other two dimensions. The aspect ratio is in the range of 10 to 400, more preferably in the range of 10 to 50, and more preferably in the range of 20 to 50. The transverse dimension is below 100 nm, and the longitudinal dimension is above 1 μm. Preferably, the transverse dimension is in the range of 5 to 60 nm. Preferably, the longitudinal dimension is in the range of 1 to 10 μm. The transverse dimension refers to the largest dimension in the direction perpendicular to the length direction of the one-dimensional feature. For example, the nanochitinous cell wall can be rod-like, in which case the transverse dimension is the diameter of the rod. For example, the nanochitinous cell wall can also be narrow strip-like, in which case the transverse dimension is the width of the strip. If the aspect ratio is too low, the nanochitinous cell wall has insufficient activity when used, and the gelation performance is poor. If the aspect ratio is too high, the preparation is difficult, and the cost is increased.

[0090] The dispersion of the nanochitinous cell wall in water has a viscosity of 200 Pa-s or more at a nanochitinous cell wall mass concentration of 0.5%, more preferably a viscosity of 2000 Pa-s or more, and more preferably a viscosity in the range of 4000 to 5000 Pa-s. The viscosity shows the stability of the system. A poor viscosity can affect the taste of the noodles. In addition, a too low viscosity can be unfavorable for the noodle processing.

[0091] The dispersion of the nanochitinous cell wall in water remains stable in the temperature range of 5 to 40°C. Remaining stable means that the stability of the dispersion system does not change significantly for more than 24 h, and preferably more than 48 h. This makes it convenient for use in noodle processing at room temperature.

[0092] In one embodiment, the total mass content of dietary fiber in the noodles is 0.5% to 1.5%. In addition to the nanochitinous cell wall as a 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 can affect the taste of the noodles.

[0093] In one embodiment, the moisture content in the noodles is 10 to 15%. The noodles with this moisture content can be stored for a longer period at room temperature, and the required cooking time is not too long.

[0094] In one embodiment, the low GI noodles comprise:

[0095] 100 parts by weight of wheat flour,

[0096] 0.4 to 0.5 parts by weight of the nanochitinous cell wall,

[0097] 1 to 5 parts by weight of edible salt.

[0098] The ratio can result in noodles with the best cooked breakage performance. The moisture content of the noodles can vary depending on whether or not a dehydration process has been performed. Dehydrating noodles is a common practice in the noodle art. Typically, fresh noodles such as hand-made noodles or commercially available fresh noodles have a total moisture content of about 30% to 35%; semi-dry noodles such as some ramen or udon noodles have a total moisture content of about 20% to 25%; and dry noodles such as dried noodles have a total moisture content of about 15% or less, such as 14.5% or less for glass noodles. Noodles that have been subjected to a dehydration process have a longer shelf life than noodles that have not been subjected to a dehydration process, and correspondingly absorb more water during the cooking process. However, the noodles of the ratio have low cooked breakage performance regardless of whether or not they have been subjected to a dehydration process.

[0099] In one embodiment, the cell source of the nanoized bamboo leaf cell wall is selected from natural bamboo, in particular, Phyllostachys pubescens. There are some difficulties in preparing the nanoized bamboo leaf cell wall using natural bamboo leaves as raw material. However, the preparation method of the present application can overcome these difficulties.

[0100] In one embodiment, the present application provides a low GI noodle improver comprising the nanoized bamboo leaf cell wall having the aforementioned features. The low GI noodle improver has the aforementioned beneficial properties. The low GI noodle improver can consist only of the nanoized bamboo leaf cell wall, for example, it can be a nanoized bamboo leaf cell wall powder, or it can contain other ingredients as long as these ingredients do not deteriorate the overall performance of the low GI noodle improver. For example, it can contain water.

[0101] In one embodiment, the low GI noodle improver is a dispersion of the nanoized bamboo leaf 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%. The dispersion can fully activate the nanoized bamboo leaf cell wall while still maintaining dispersion stability for ease of use in the noodle making process.

[0102] In one embodiment, the present application provides a method for preparing the low GI noodle improver of the present application, the method comprising preparing the nanoized bamboo leaf cell wall by the following steps:

[0103] A) adding a natural bamboo cell source to a solution of noodle grade anhydrous ethanol, warming to 60 to 80°C, and reacting for 24 to 48 h;

[0104] B) adding the mixture obtained in step A) to a solution of a mixture of noodle grade hydrogen peroxide and noodle grade glacial acetic acid, reacting at 60 to 80°C for 24 to 48 h to obtain bleached bamboo leaf cell wall;

[0105] C) pulverizing the bleached bamboo leaf cell wall obtained in step B) using post-treatment including high pressure homogenization to obtain the nanoized bamboo leaf cell wall.

[0106] Without being bound by any theory, the step A) before bleaching in the preparation method of the present application is important. It can facilitate the natural bamboo leaves to release the cell walls of the parenchyma cells, while removing some of the substances in the parenchyma cells that are soluble in ethanol and can interfere with the subsequent bleaching process in advance. By implementing step A), compared with the aforementioned Chinese patent application CN202110607105.3, the concentration of glacial acetic acid used can be reduced to about 60% to 80%, and the concentration of hydrogen peroxide can also be reduced to less than 30%, reducing the process requirements.

[0107] In particular, step A) of the preparation method of the present application can help overcome the difficulty of preparing nanoscale bamboo leaf cell walls from bamboo leaf cell sources. Compared with wood raw materials, the cell walls of bamboo raw materials contain a relatively high amount of waxes. The presence of waxes hinders the reaction of hydrogen peroxide and glacial acetic acid on the cell source on the one hand, and is easily left in the final product after bleaching and crushing, which has a potential impact on the properties of noodles. For bamboo leaf raw materials, the present application effectively dissolves the waxes by pre-treating with anhydrous ethanol, reducing its adverse effects in the bleaching step, and also facilitating the release of cellulose from natural plants. In addition, it also reduces the residual waxes in the noodle improver, reducing the adverse effects on the final noodle product.

[0108] In one embodiment, the present application provides a noodle comprising the low GI noodle improver of the present application, which can be a dispersion of the nanoscale bamboo leaf cell wall in water with a mass concentration of 0.1% to 3%, preferably 0.3% to 2.5%, more preferably 0.5% to 2%, and the mass ratio of the low GI noodle improver to flour in the starch-like system can be in the range of 1:1 to 1:5, preferably 1:2-1:4. The selected range can sufficiently control the glycemic index after noodle intake, and still maintain the noodle properties such as taste, stability, etc.

[0109] The present application provides a method for preparing the low GI noodle of the present application, comprising the following steps:

[0110] (1) First mix the nanoscale bamboo leaf cell wall with water, edible salt, and then add wheat flour, stir evenly to make a dough;

[0111] (2) The dough is proofed in a constant temperature and humidity environment, then rolled and cut into noodles.

[0112] After the nanoized bamboo leaf cell wall is prepared, the noodles can be prepared by the conventional mixing and stirring method. In the present application, the nanoized bamboo leaf cell wall is mixed with water and edible salt before the flour is added. This has the advantage that the nanoized bamboo leaf cell wall is more easily activated. Typically, the mixing is carried out in a mixer. When preparing fresh noodles, the total water content in the mixture can be about 30% to 40% for the purpose of easy dough mixing, which corresponds to about 40 to 70 parts of water for 100 parts of flour.

[0113] 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 min. Such stirring can mix the noodle raw materials sufficiently and can form a gluten network that is sufficiently expanded and uniformly distributed in the raw material mixture of the present application, which is conducive to forming noodles that are tough, resistant to cooking and have good taste.

[0114] Resting allows the water to be uniformly distributed and allows the gluten network to relax, improving the noodle processing performance. Preferably, in step (2), the constant temperature and humidity environment for resting is: constant temperature at 20 to 40°C, constant humidity at 60% to 80%, for 1 to 4 h. Under this constant temperature and humidity environment and resting time, the dough becomes easy to calender.

[0115] Preferably, the method of the present application further comprises a dehydration treatment after the noodles are formed. The dried noodles obtained after the dehydration treatment are easy to store. The dried noodles require slightly longer cooking time when cooked, but their breakage rate and taste are not substantially affected.

[0116] Preferably, the dehydration treatment comprises the following stages:

[0117] First stage: temperature 25°C, humidity 60% to 80%, cycle frequency 40 Hz, time 10 to 30 min;

[0118] Second stage: temperature 40°C, humidity 75% to 85%, cycle frequency 40 Hz, time 40 to 60 min;

[0119] Third stage: temperature 45°C, humidity 60% to 70%, cycle frequency 40 Hz, time 80 to 120 min;

[0120] Fourth stage: temperature 30°C, humidity 50% to 60%, cycle frequency 40 Hz, time 20 to 40 min.

[0121] The circulation frequency refers to the circulation working frequency of the air flow or the dehumidification system in a conventional dewatering device in the art. The advantage of the staged dewatering is that the water in the noodles can be removed gradually and uniformly, avoiding the cracking, deformation or internal stress unevenness of the noodles due to the too fast drying, so as to effectively control the broken noodle rate and maintain the original shape and taste of the noodles after rehydration.

[0122] Preferably, the nanofiber bamboo leaf cell wall in (1) is prepared by the following steps:

[0123] A) adding bamboo leaves into food-grade anhydrous ethanol, heating to 60-80℃, and reacting for 24-48 h;

[0124] B) adding the mixture obtained in step A) into a solution of mixed food-grade hydrogen peroxide and food-grade glacial acetic acid, and reacting at 60-80℃ for 24-48 h to obtain bleached bamboo leaf cell wall;

[0125] C) using post-treatment including high-pressure homogenization to crush the bleached bamboo leaf cell wall obtained in step B) to obtain the nanofiber bamboo leaf cell wall.

[0126] The preparation method can conveniently and efficiently prepare the nanofiber bamboo leaf cell wall with the required morphology.

[0127] Regarding the preparation of the nanofiber bamboo leaf cell wall, more preferably, the transverse size distribution range of the obtained nanofiber bamboo leaf cell wall is 5-60 nm, the longitudinal size distribution range is 1-10 μm, and the aspect ratio distribution range is 10-400, more preferably 10-50, more preferably 20-50. In addition, preferably, the surface charge distribution range is -60 to -10 mV. The surface charge distribution range is beneficial to improve the stability.

[0128] The preferred nanofiber bamboo leaf cell wall preparation method of the present application can also be referred to as an edible stripping method. The term "edible stripping method" refers to a safe and edible nanofiber bamboo leaf cell wall preparation method obtained by treatment with food-grade reagents and mechanical treatment, in which most of the lignin and part of the hemicellulose in the cell wall are "stripped" therefrom, as much as possible without changing the natural microstructure of the cellulose arrangement. In the present application, the food-grade reagents include food-grade anhydrous ethanol, food-grade glacial acetic acid and food-grade hydrogen peroxide.

[0129] Preferably, before step A), it can also include: soaking the commercially available Phyllostachys pubescens leaves with deionized water for multiple times to remove most of the salt on the surface.

[0130] Preferably, in step A), the mass ratio of bamboo leaf raw material to anhydrous ethanol is 1:3 to 1:15, preferably 1:5 to 1:10.

[0131] More preferably, the temperature in step A) of the present application is 75 to 80 °C, and the holding time is more preferably 36 to 48 h.

[0132] Preferably, in step B) of the present application, 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 mixture of the two is 1:5 to 1:20; the mass ratio of bamboo leaf raw material to reaction solution is 1:3 to 1:5.

[0133] In step C) of the present application, post-treatment including high-pressure homogenization is used. High-pressure homogenization crushing method relies on the process of liquid pressurization and pressure release to complete the crushing of materials through effects such as shearing, cavitation, and impact. The inventors found that when the plant cell source comes from herbaceous plants, compared with woody plant sources, it contains a relatively high content of silicon dioxide, which is a high-hardness material. If mechanical crushing such as high-speed rotating cutter head is used, the cutter head may quickly wear out, resulting in reduced processing efficiency and potentially introducing impurity particles. High-pressure homogenization can avoid these shortcomings, and is therefore particularly suitable for preparing nanoized bamboo leaf cell walls from herbaceous plants. Preferably, the mechanical pulverization of the bleached bamboo leaf cell wall dispersion includes any one or a combination of high-pressure homogenizer, cell ultrasonic crusher, and beater, and the mechanical pulverization time is 1 to 5 h. Preferably, the mass concentration of the dispersion of bamboo leaf cell walls in water is 0.5% to 2%. Preferably, the high-pressure homogenization process can be carried out for 2 to 5 hours.

[0134] The above preparation method can achieve the purpose of making the nanoized bamboo leaf cell wall extracted from bamboo leaves have the desired high crystallinity, high aspect ratio, and excellent mechanical and thermal stability, etc., to realize the use of the present application as a low GI noodle modifier.

[0135] Through the method of the present application, no toxic or harmful solvents are added in the process of extracting nanoized bamboo leaf cell walls from bamboo leaves, the environmental pollution is small, the energy consumption is low, the stripping process is simple and efficient, and the obtained nanoized bamboo leaf cell walls have food safety characteristics.

[0136] The low GI noodle modifier of the present application uses nanoized bamboo leaf cell walls with special properties, and when used in the noodle system, especially in starch-like, it also has the function of reducing rapidly digestible starch, slowly digestible starch, and increasing resistant starch.

[0137] In the present application, the process of combining the low GI noodle modifier with starch and its performance characterization can include the following steps:

[0138] Step a) : The prepared nano-bamboo leaf cell wall aqueous dispersion is added with a certain amount of deionized water or a certain amount of water is removed to adjust the mass concentration, and a nano-bamboo leaf cell wall aqueous dispersion with a mass concentration of 0.1 to 3% is prepared, preferably a concentration of 0.3 to 2.5%, more preferably 0.5 to 2%;

[0139] Step b) : The nano-bamboo leaf cell wall aqueous dispersion obtained in step a) is added to starch, and the nano-bamboo leaf cell wall aqueous dispersion and starch are compounded in a mass ratio of 1:1 to 1:5, preferably 1:2 to 1:4, and then uniformly mixed and dispersed by mechanical means, and then can be placed in a refrigerator for 30 to 60 min;

[0140] Step c) : The uniformly dispersed mixed solution obtained in step b) is taken out (for example, 5 to 10 mL or 5 to 10 grams) and placed in a glass beaker, and a viscosity measurement method is selected to test the rheological properties of the material. For example, a TA Instruments Waters HR20 rheometer can be used for measurement. A parallel plate with a diameter of 60 mm is selected, and the shear rate is measured from 0.01 to 100 s -1 The change of the solution viscosity, and the change of the solution storage modulus and loss modulus. -1 The change of the solution viscosity, and the change of the solution storage modulus and loss modulus.

[0141] The mechanical stirring in step b) above can use a magnetic stirrer, an ultrasonic stirrer, a polytetrafluoroethylene stirrer, or a cell disrupter, preferably a magnetic stirrer and a cell disrupter, and more preferably a cell disrupter; the stirring rate of the mechanical stirring is in the range of 1500 to 3000 r / min -1 The stirring time is 2 to 15 min, and the standing time in the refrigerator is preferably 10 to 15 min.

[0142] In the present application, the nano-bamboo leaf cell wall is added to starch, and a dense network structure with good stability is formed between the nano-bamboo leaf cell wall and the starch, which can exhibit one or more of the following effects:

[0143] i) The low GI noodle modifier is added to the desired starch-like system, and the structure of the prepared starch-like system is more dense;

[0144] ii) The low GI noodle modifier is added to the desired starch-like system, and the viscosity and storage modulus are significantly improved;

[0145] iii) The low GI noodle modifier is added to the starch-like system and gelatinized, and then in vitro simulated digestion experiment is carried out, and with the increase of the concentration of the nano-bamboo leaf cell wall extracted from the bamboo leaf, the content of rapidly digestible starch and slowly digestible starch decreases, and the content of resistant starch increases.

[0146] When the low GI noodle improver is added to the porcine pancreatic amylase liquid system, it can interact with the amylase to reduce the amylase activity.

[0147] In order to further understand the present application, the application of the nanoized bamboo leaf cell wall in the field of inhibiting starch digestion and the corresponding inhibition effect thereof are further described below in combination with examples. The protection scope of the present application is not limited by the following examples.

[0148] Examples

[0149] The example uses Phyllostachys pubescens leaves as a natural plant source for providing bamboo leaf cell walls, which are purchased from a bamboo original home store on Taobao. The appearance of the raw material is shown in Figure 1 .

[0150] The characterization experiment method for the target performance parameters in the example uses a method commonly used in the art.

[0151] Nanoized bamboo leaf cell wall preparation example 1

[0152] The nanoized bamboo leaf cell wall is prepared by the following steps.

[0153] First, 1000 g of Phyllostachys pubescens leaves are soaked in deionized water multiple times to remove most of the salt on the surface.

[0154] Subsequently, the desalted Phyllostachys pubescens leaves are added to food-grade anhydrous ethanol in a reaction container at 80°C for 12 h to promote the bleaching property of the cell wall of the bamboo leaves, and the ratio is 1:6.

[0155] The reacted Phyllostachys pubescens leaves are washed with deionized water and then put into 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 for bleaching. The concentration of the hydrogen peroxide aqueous solution is 20%, the concentration of the glacial acetic acid aqueous solution is 60%, and the mass ratio of the mixture is 1:10. The reaction time is 24 h, and the reaction temperature is 60°C.

[0156] After the bleaching step, the obtained mixture is allowed to stand and stratify. The upper layer is a floating pulp-like material, the lower layer is a liquid, and the bottom layer is a precipitate. The upper layer of the pulp-like material is separated and washed with water, an appropriate amount of water is added, and then it is crushed in a beater for 1 h and then broken by a high-pressure homogenizer for 120 minutes to obtain a nanoized bamboo leaf cell wall dispersion.

[0157] Figure 2The photos showing different stages of the preparation of the nano-bamboo leaf cell wall of Phyllostachys pubescens are shown from left to right as follows: bamboo leaf raw material, Phyllostachys pubescens leaves immersed in a bleaching mixed solution after reacting with food-grade anhydrous ethanol, and the nano-bamboo leaf cell wall dispersion liquid after high-pressure homogenization. It can be observed intuitively that the size of the Phyllostachys pubescens raw material gradually becomes smaller and finer as the method of the present application proceeds, and finally the nano-bamboo leaf cell wall is obtained. As can be seen from the rightmost photo, a uniformly dispersed, translucent white dispersion liquid can be obtained.

[0158] Figure 3 The scanning electron micrograph of the Phyllostachys pubescens raw material is shown. The morphology of the cell wall of the closely arranged parenchyma cells is shown.

[0159] Figure 4 The X-ray diffraction curve of the obtained nano-bamboo leaf cell wall sample is shown. The characteristic peaks show that the main component in the obtained sample is cellulose. The crystallinity of cellulose can be calculated from the X-ray diffraction curve. Multiple repeated preparation experiments show that the crystallinity of cellulose obtained according to the preparation method of Preparation Example 1 is 80% to 95%.

[0160] Figure 5 The image of a piece of one-dimensional nano-bamboo leaf cell wall observed under an electron microscope is shown. The scale is shown at the bottom of the image.

[0161] The rheological performance of the obtained dispersion liquid was tested after adjusting the concentration to 0.5% using a HAAKE MARS 60 rotary rheometer. A parallel plate with a diameter of 60 mm was selected, and the shear rate was measured from 0.01 to 100 s -1 The change of the solution viscosity, and the frequency was 1 to 100 rad s -1 The change of the solution storage modulus and loss modulus.

[0162] Multiple repeated experiments show that the aqueous dispersion liquid of the obtained nano-bamboo leaf cell wall has a viscosity of 200 Pa•s or more when the mass concentration of the nano-bamboo leaf cell wall is 0.5%, and remains stable for 24 hours or more within a temperature range of 5 to 40°C.

[0163] Preparation Example 2 of nano-bamboo leaf cell wall

[0164] The nano-bamboo leaf cell wall was prepared in a substantially same manner as in Preparation Example 1 of nano-bamboo leaf cell wall, except that: the reaction time was 24 h during the food-grade anhydrous ethanol treatment; the concentration of the hydrogen peroxide aqueous solution was 30%, the concentration of the glacial acetic acid aqueous solution was 80%, the volume ratio of the mixture of the two was 1:20, the reaction time was 48 h, and the reaction temperature was 80°C during the bleaching process; and the smashing was carried out in a beater for 2 h, and then the smashing was carried out by a high-pressure homogenizer for 90 minutes during the smashing process.

[0165] The product was subjected to the aforementioned detection characterization, and the results were consistent with those of the nanoized bamboo leaf cell wall preparation example 1.

[0166] Noodle modifier performance example 1

[0167] The product from the nanoized bamboo leaf cell wall preparation example 1 was used as a low GI noodle modifier to be added to a starch-like system for testing. Before being added, the proportion of the low GI noodle modifier content in the dispersion was adjusted. Specifically, the product from the nanoized bamboo leaf cell wall preparation example 1 was taken, the solid content was calculated by weighing after drying, and a certain amount of water was added or evaporated according to the calculation result to obtain a water dispersion of a predetermined mass concentration of the nanoized bamboo leaf cell wall. In this way, water dispersions of nanoized bamboo leaf cell wall with mass concentrations of 0.5%, 1%, and 1.5% were prepared as low GI noodle modifier samples.

[0168] The uniformly dispersed mixture obtained after gelatinization was left to stand in a freezer for 30 to 60 min. 10 g was taken and placed in a glass beaker, and a HAAKE MARS 60 rotary rheometer was used to test the rheological properties of the material. A parallel plate with a diameter of 60 mm was selected, and the shear rate was measured from 0.01 to 100 s -1 The change in solution viscosity with shear rate, and the change in solution storage modulus and loss modulus with frequency from 1 to 100 rad / s. -1 The change in solution viscosity with shear rate, and the change in solution storage modulus and loss modulus with frequency from 1 to 100 rad / s. Figure 7 Figure 8A and Figure 8B The measurement results are shown.

[0169] Figure 7 Figure 8A and Figure 8B The rheological data curves of the mixed system obtained by adding each low GI noodle modifier sample to starch at a mass ratio of 1:2 are shown, showing the relationship between viscosity and shear rate, and the relationship between storage modulus and loss modulus and frequency.

[0170] Noodle modifier performance example 2

[0171] The low GI noodle modifier samples were prepared in the same way as in the noodle modifier performance example 1.

[0172] The low GI noodle modifier sample with a nanoized bamboo leaf cell wall concentration of 0.5% and porcine pancreatic amylase were mixed at a mass ratio of 10:1, stirred at room temperature, and left to stand at room temperature for 20 min after uniform stirring to obtain a uniformly mixed solution system.

[0173] Figure 9 The ultraviolet spectrum of the mixed system measured using the ultraviolet visible near-infrared spectrophotometer SOLID 3700 is shown.​​

[0174] Figure 10 The fluorescence spectrum of the mixed system measured using an X-ray fluorescence spectrometer XRF-1800 is shown.

[0175] Figure 9 、 10 Microscopically, it is shown that the nanofiberized bamboo leaf cell wall reduces the activity of the enzyme, thereby inhibiting digestion.

[0176] The mixed solution system obtained can be taken out 1 mL of supernatant in a glass beaker, and measured by an enzyme marker to calculate the porcine pancreatic amylase activity data. Compared with the blank group, it is shown that the porcine pancreatic amylase activity is reduced.

[0177] Without being bound by any theory, the low GI noodle modifier of the present application can inhibit the activity of α-amylase and hinder starch digestion through physical and chemical interactions and steric hindrance effects, achieving a low GI effect. Specifically, the functional groups such as hydroxyl and carboxyl groups on the surface of the nanofiberized bamboo leaf cell wall can directly adsorb α-amylase molecules through electrostatic interactions and hydrogen bonds, resulting in the enzyme active center being shielded or the conformation being changed. In addition to the inhibition of amylase molecules, the three-dimensional network structure formed by the nanofiberized bamboo leaf cell wall in the starch matrix can physically block the contact between α-amylase and starch molecules, significantly reducing the enzymatic efficiency. In addition, the nanofiberized bamboo leaf cell wall can also affect the gelatinization and retrogradation properties of starch by preferentially binding to amylose, further reducing the exposure of enzymatic sites. These synergistic effects ultimately result in a significant reduction in the rate and extent of starch digestion. In particular, the nanofiberized bamboo leaf cell wall of the present application may have a better effect on inhibiting amylase than cellulose nanocrystals obtained by conventional strong acid hydrolysis due to its retention of part of the natural structure of the cell wall and its specific morphology.

[0178] Noodle modifier performance example 3

[0179] The low GI noodle modifier samples were prepared in the same way as in Noodle modifier performance example 1 and mixed with starch for gelatinization.

[0180] Figure 11 The contents of rapidly digestible starch, slowly digestible starch and resistant starch of these mixed systems measured using an ST-360 enzyme marker are shown.

[0181] Figure 11 It is shown that after adding the low GI noodle modifier, the contents of rapidly digestible starch and slowly digestible starch are reduced, and the content of resistant starch is increased, achieving a low GI effect.

[0182] The low-GI noodle improver of the present application can effectively reduce the proportion of rapidly digestible starch and slowly digestible starch in starch and increase the proportion of resistant starch after being added to starch due to the nanoscale and one-dimensional characteristics of the nano-sized bamboo leaf cell wall, which has a high specific surface area and forms a network structure, thereby further improving the low-GI effect.

[0183] Noodle improver performance example 4

[0184] A cytotoxicity experiment was performed on gastric epithelial cells using the low-GI noodle improver. The control group was normal cultured cells without the addition of the low-GI noodle improver. The results showed that the cell activities of the two groups were the same, proving that the low-GI noodle improver of the present application is non-toxic.

[0185] Figure 12 A cytotoxicity experiment was performed on gastric epithelial cells using the low-GI noodle improver. The control group was normal cultured cells without the addition of the low-GI noodle improver. The results showed that the cell activities of the two groups were the same, proving that the low-GI noodle improver of the present application is non-toxic.

[0186] It can be seen that the nano-sized bamboo leaf cell wall is non-toxic to gastric epithelial cells.

[0187] Comparative example 1

[0188] This comparative example is the same as noodle improver performance example 1, except that the nano-sized bamboo leaf cell wall is replaced by cellulose nanocrystals (CNC) with a mass concentration of 0.5%. The CNC used in the comparative example is obtained by retaining only the crystalline region of cellulose from wood through strong acid hydrolysis using a conventional method.

[0189] Figure 7 、 Figure 8A 、 Figure 8B Rheological data obtained using the nano-sized bamboo leaf cell wall and cellulose nanocrystals in noodle improver performance example 1 and comparative example 1.

[0190] Compared with the addition of cellulose nanocrystals, the addition of the nano-sized bamboo leaf cell wall of the present application results in a larger viscosity of the system, as well as larger storage modulus and loss modulus. The processability of the mixture system of the present application is better.

[0191] Comparative example 2

[0192] This comparative example is the same as noodle improver performance example 3, except that the nano-sized bamboo leaf cell wall is replaced by cellulose nanocrystals with a mass concentration of 0.5%.

[0193] Figure 11The performance of the noodle improver was assessed in Example 3 and Comparative Example 2, which used nano-sized bamboo leaf cell walls and cellulose nanocrystals at mass concentrations of 0.5%, 1%, and 1.5% 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 leaf 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.

[0194] Comparative Example 3

[0195] The preparation was carried out in the same manner as in Example 1 of the preparation of nano-sized bamboo leaf cell walls, except that the anhydrous ethanol reaction step was not performed.

[0196] The same characterization of the product showed that its hemicellulose and lignin residues were high and its one-dimensional characteristics were poor.

[0197] Noodle preparation example

[0198] Noodles were prepared using the nano-sized bamboo leaf cell walls obtained in Example 1. The specific preparation process is as follows:

[0199] (1) Mix 40 parts of the aqueous dispersion of the nano-sized bamboo leaf cell wall with an additional 10 parts of water and 3 parts of edible salt, then add 100 parts of wheat flour, stir evenly, and make dough, wherein the mass ratio of the nano-sized bamboo leaf cell wall to wheat flour is 0.4%;

[0200] (2) The dough is rested in a constant temperature and humidity environment, then rolled and cut into strips to form noodles;

[0201] (3) Dehydrate the formed noodles.

[0202] 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.

[0203] The dehydration process includes the following stages:

[0204] Phase 1: Temperature 25℃, humidity 80%, cycle frequency 40Hz, duration 30min;

[0205] Second stage: Temperature 40℃, humidity 85%, circulation frequency 40Hz, duration 60min;

[0206] Third stage: Temperature 45℃, humidity 70%, circulation frequency 40Hz, duration 120min;

[0207] The fourth stage: temperature 30℃, humidity 60%, cycle frequency 40Hz, time length 40min.

[0208] The appearance of the prepared noodles is as shown in the photo. Figure 6

[0209] The prepared noodles are tested for performance 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 Table 1. Figure 13

[0210] It can be seen that the noodles prepared by adding the nanoized bamboo leaf cell wall to the noodle raw materials not only achieve the low GI function, but also the performance still fully meets the national standards, and some parameters perform outstandingly, for example, it has extremely low acidity and natural breaking rate. Especially outstanding is that its cooked breaking rate can be as low as 0. In addition, it maintains the proper taste of noodles.

[0211] It can be seen that the nanoized bamboo leaf cell wall obtained by the present application added to starch verifies that the material has the effect of inhibiting the increase of GI through multiple mechanisms, so it will have broad application prospects in the field of low GI noodles and the like. The nanoized cell wall extracted from natural plants added to the noodle product system of the present application can not only reduce the glycemic index to obtain low GI noodles, but also improve the stability and maintain the taste of noodles. The preparation method can obtain the required nanoized bamboo leaf cell wall simply, non-toxicly, efficiently and environmentally friendly, and the anhydrous ethanol treatment improves the preparation effect.

[0212] The above specific embodiments and examples are only used to help understand the method of the present application and its core idea. It should be noted that for those skilled in the art, without departing from the principles and spirit of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.​​

Claims

1. A low GI noodle, characterized by, It comprises: Nanoized bamboo leaf cell wall, wheat flour, water and edible salt, wherein the mass ratio of the nanoized bamboo leaf cell wall to the wheat flour is 0.3% to 0.6%, the nanoized bamboo leaf cell wall is edible; the cellulose in the nanoized bamboo leaf cell wall has a crystallinity of 80% to 95%; the nanoized bamboo leaf cell wall has a one-dimensional feature, with a lateral size below 100 nm and a longitudinal size above 1 μm; the dispersion of the nanoized bamboo leaf cell wall in water has a viscosity of 200 Pa•s or above at a mass concentration of 0.5% of the nanoized bamboo leaf cell wall and remains stable within a temperature range of 5 to 40℃.

2. The low-GI noodle according to claim 1, characterized by, wherein the total mass content of dietary fiber is 0.5% to 1.5%.

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

4. The low-GI noodle according to claim 1, characterized by, The low GI noodles comprise: 100 parts by weight of wheat flour, 0.4 to 0.5 parts by weight of the nanoized bamboo leaf cell wall, 1 to 5 parts by weight of edible salt.

5. A method for preparing the low-GI noodle according to claim 1, characterized by, comprising the following steps: (1) mixing the nanoized bamboo leaf cell wall with water and edible salt, and then adding wheat flour, stirring uniformly to obtain a dough; (2) proofing the dough in a constant temperature and humidity environment, and then calendering and cutting to form noodles.

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

7. The method according to claim 5, wherein, in step (2), the constant temperature and humidity environment for proofing is: a constant temperature of 20℃ to 40℃, a constant humidity of 60% to 80%, and a time of 1 to 4 h.

8. The method of claim 5, wherein, The method further comprises a dehydration treatment after forming the noodles.

9. The method of claim 8, wherein, The dehydration treatment comprises the following stages: first stage: temperature 25℃, humidity 60% to 80%, cycle frequency 40 Hz, time length 10 to 30 min; second stage: temperature 40℃, humidity 75% to 85%, cycle frequency 40 Hz, time length 40 to 60 min; third stage: temperature 45℃, humidity 60% to 70%, cycle frequency 40 Hz, time length 80 to 120 min; fourth stage: temperature 30℃, humidity 50% to 60%, cycle frequency 40 Hz, time length 20 to 40 min.

10. The method of claim 5, wherein, The nanoized bamboo leaf cell wall in (1) is prepared by the following steps: A) adding bamboo leaves to food-grade anhydrous ethanol, heating to 60 to 80℃, and reacting for 24 to 48 h; B) adding the mixture obtained in step A) to a solution of food-grade hydrogen peroxide and food-grade glacial acetic acid mixed together, reacting at 60 to 80℃ for 24 to 48 h to obtain bleached bamboo leaf cell wall; C) using post-treatment including high-pressure homogenization to crush the bleached bamboo leaf cell wall obtained in step B) to obtain the nanoized bamboo leaf cell wall.

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