A polysaccharide-based edible straw and a method for preparing the same

Abstract

The application provides a polysaccharide-based edible straw and a preparation method thereof. A main structure of the polysaccharide-based edible straw is made of a composite hydrogel of starch and bacterial cellulose, and the polysaccharide-based edible straw comprises: a plurality of layers of bacterial cellulose layers, a starch layer interpenetrated through a three-dimensional network between each layer of the bacterial cellulose layers to play a bonding role, and an edible water-resistant layer located on a surface of the straw. The polysaccharide-based edible straw provided by the application has the characteristics of high strength, high deformation resistance, high water resistance, no micro-plastic release and the like, and is healthy and edible, biodegradable, and is a favorable competitor of traditional straws on the market.

Description

Technical Field

[0001] This invention relates to the field of edible new material development technology, specifically to an edible straw based on a polysaccharide compound of bacterial cellulose and starch obtained by biosynthesis and its preparation method. Background Technology

[0002] The widespread use of plastics in daily life has provided convenience, but the degradation process of large quantities of waste plastics, influenced by sunlight, temperature, mechanical wear, and other factors, results in the breakdown of these plastics, producing a significant amount of microplastics. Due to their small particle size, microplastics possess tissue affinity, making them more easily adsorbed onto cell surfaces, thereby disrupting membrane structures, triggering inflammatory responses, and even causing cancer. In recent years, scientists have discovered the presence of microplastics in the ocean, human blood, and even human breast milk, posing a significant threat to human health. With the development of the beverage industry, the widespread use of plastic straws also poses a serious threat to ecosystems and human health.

[0003] Polysaccharides are widely distributed in nature. Some are components of the cell walls of plants and animals, while others serve as nutrients stored in these organisms. Cellulose and starch are the two main types of polysaccharides found in nature. Bacterial cellulose, primarily synthesized and secreted by bacteria (such as *Acetobacter xylinum*), is a cellulose with a rich three-dimensional network structure and is commonly used as a beverage additive, particularly in coconut jelly. It is low in calories and rich in dietary fiber. Bacterial cellulose possesses numerous excellent properties, such as biodegradability, high Young's modulus, high strength, high crystallinity, and large specific surface area, giving it broad application potential and value in many fields. Furthermore, bacterial cellulose exhibits higher crystallinity and polymerization than plant-derived cellulose, resulting in better mechanical properties. Starch, mainly derived from the roots and stems of most plants, rapidly absorbs water, swells, and collapses within a certain temperature range, forming a viscous, homogeneous, transparent paste solution, thus becoming a natural binder. Besides their respective excellent properties and edibility, both bacterial cellulose and starch exhibit excellent biocompatibility and biodegradability, making them more environmentally friendly than traditional petroleum-based materials.

[0004] The inventors of this application have been deeply involved in the development of edible new materials. Their Chinese patent CN202111683390.3 discloses a bacterial cellulose-based edible straw and its preparation method. In this patent application, sodium alginate is used, and it acts as a three-dimensional network interpenetrating and stitching agent between bacterial cellulose fibers. Furthermore, cross-linking with an inorganic cross-linking agent is required before use. Starch is more widely available and cheaper than sodium alginate. Sodium alginate has stable viscosity and high surface tension, which allows it to maintain high adhesive properties at high temperatures. In contrast, starch typically has low strength and poor water resistance, easily softening in water, changing shape, or even losing its adhesive ability. Therefore, using starch in the straw field presents more technical challenges. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a polysaccharide-based (bacterial cellulose and starch) edible straw and its preparation method. The polysaccharide-based edible straw provided by this application has a variety of characteristics and functions, such as high strength, high resistance to deformation, no microplastic release, edibility, biodegradability, and the ability to load pigment molecules, flavor molecules, natural plant extracts and drug molecules.

[0006] Therefore, this application provides the following aspects:

[0007] <1> A polysaccharide-based edible straw, the main structure of which is made of a composite hydrogel of starch and bacterial cellulose, the polysaccharide-based edible straw comprising: multiple layers of bacterial cellulose, a starch layer that acts as a three-dimensional network between the layers of bacterial cellulose to achieve bonding, and an edible water-resistant layer located on the surface of the straw.

[0008] <2> .according to <1> The polysaccharide-based edible straw, wherein the thickness of a single layer of the multi-layered bacterial cellulose layer is 20-200 μm.

[0009] <3> .according to <1> The polysaccharide-based edible straw has an inner diameter ranging from 5mm to 12mm and a wall thickness ranging from 0.1mm to 5mm.

[0010] <4> .according to <1> The polysaccharide-based edible straw, wherein the thickness of the bacterial cellulose composite hydrogel is 0.1-3 cm.

[0011] <5> .according to <1> The polysaccharide-based edible straw, wherein the edible water-resistant layer is an edible beeswax layer.

[0012] <6> The polysaccharide-based edible straw according to claim 1, wherein the straw is a colored straw.

[0013] <7> A method for preparing according to <1> to <6> The method for making polysaccharide-based edible straws according to any one of the following steps:

[0014] A) In the process of using bacteria to synthesize bacterial cellulose, starch is introduced to synthesize a composite hydrogel in which starch is uniformly dispersed in bacterial cellulose.

[0015] B) Treat the composite hydrogel obtained in step A) in an edible soda ash aqueous solution;

[0016] C) The composite hydrogel obtained in step B) is dried at room temperature to 80°C to form a film;

[0017] D) Place the film obtained in step C) into water for thermal crosslinking to obtain a crosslinked composite film.

[0018] E) The cross-linked composite film obtained in step D) is wound into a tube to obtain a tube as the main structure;

[0019] F) Form a water-resistant layer on the surface of the rolled tube obtained in step E) to obtain a polysaccharide-based edible straw.

[0020] <8> .according to <7> The method wherein the synthetic cellulose bacteria are selected from one or more of Acetobacter xylinum, Agrobacterium, Rhizobium, and Diplococcus.

[0021] <9> .according to <7> The method, wherein step A) includes the following process:

[0022] Using 1 liter of water (solvent) as a reference, prepare a solution containing 10-100 g / L of water. -1 Glucose, 1-40 g / L -1 Yeast extract, 1-50g / L -1 A solid culture medium composed of agar, prepared using 1 liter of water (solvent) as a standard, consists of 10-100 g / L of agar. -1 Glucose, 1-40 g / L -1 Yeast extract, 0.1-10 g / L -1 Citric acid, 0.1-10 g / L -1 Na2HPO4·12H2O and 0.1-10 gL -1 A liquid culture medium composed of KH2PO4 was then added, along with solid culture medium, liquid culture medium, and 10-100 g L... -1The dried starch was sterilized in an autoclave at 110-150℃ for 5-90 minutes. After sterilization, the bacteria that produce bacterial cellulose were inoculated into a solid culture medium. After continuous fermentation at a constant temperature of 25-30℃, the sterilized starch was mixed with a liquid culture medium. Then, the liquid culture medium containing starch was added to the growing bacterial cellulose using aerosol-assisted synthesis to obtain a composite hydrogel.

[0023] <10> .according to <7> The method wherein the thermal crosslinking temperature in step D) is 90-100℃ and the crosslinking time is 5-10 min.

[0024] <11> .according to <7> The method wherein the inner diameter of the food-grade PTFE rod in step E) is 5-12 mm, and the drying temperature in the oven is 40-80℃.

[0025] <12> .according to <7> The method wherein the starch is selected from corn starch, potato starch, or sweet potato starch.

[0026] The polysaccharide-based edible straw of the present invention possesses excellent mechanical properties due to its ultra-fine physical coating and interconnection of a three-dimensional nano-network structure composed of bacterial cellulose and starch, and a multi-scale starch-bacterial cellulose composite layered structure. This three-dimensional interpenetrating network structure and layered structure with ultra-high density hydrogen bonds and physical entanglement endow the straw with superior mechanical properties. Under the same shape parameters, the straw of the present invention has a three-point bending strength exceeding 40 MPa, approximately six times that of a PLA straw; its compression cycle performance is close to 60 MPa, approximately four times that of a PLA straw. Furthermore, the polysaccharide-based edible straw has a loading capacity not found in traditional straws. Its internal ultra-fine three-dimensional nano-network can confine various molecules, enabling it to load natural pigment molecules and flavor molecules, thus giving it ideal color and aroma. It can also load natural plant extracts, which are beneficial to health, and some drug molecules, providing certain health and therapeutic effects. Attached Figure Description

[0027] Figure 1 A photograph of the polysaccharide-based edible straw prepared in Example 1 of this invention;

[0028] Figure 2 This is a microscopic photograph of the bacterial cellulose hydrogel prepared in Example 1 of the present invention after supercritical drying, observed under a field emission scanning electron microscope.

[0029] Figure 3 Microscopic images of the polysaccharide-based edible straws prepared in Example 1 of the present invention, observed under a field emission scanning electron microscope;

[0030] Figure 4A larger-scale microscopic image of the polysaccharide-based edible straw prepared in Example 1 of the present invention, observed under a field emission scanning electron microscope;

[0031] Figure 5 Microscopic photographs of the tensile cross-section of the polysaccharide-based edible straw prepared in Example 1 of the present invention, observed under a field emission scanning electron microscope.

[0032] Figure 6 The three-point bending properties of the polysaccharide-based edible straw prepared in Example 1 of this invention at room temperature are compared with those of commercially available disposable straws. This data was obtained by testing on a universal mechanical testing instrument.

[0033] Figure 7 The three-point bending mechanical properties of the polysaccharide-based edible straw prepared in Example 1 at low temperature (0°C) are compared with those of commercially available disposable straws. The data were obtained by testing on a universal mechanical testing instrument.

[0034] Figure 8 The three-point bending mechanical properties of the polysaccharide-based edible straw prepared in Example 1 at high temperature (80°C) are compared with those of commercially available disposable straws. The data were obtained by testing on a universal mechanical testing instrument.

[0035] Figure 9 The compressive mechanical properties of the polysaccharide-based edible straw prepared in Example 1 are compared with those of commercially available disposable straws. The data were obtained by testing on a universal mechanical testing instrument.

[0036] Figure 10 The changes and comparisons of the three-point bending strength of the polysaccharide-based edible straw and paper straw prepared in Example 1 after soaking in water were obtained by testing on a universal mechanical testing instrument.

[0037] Figure 11 The relative activity of human intestinal epithelial cells in the polysaccharide-based edible straw material prepared in Example 1;

[0038] Figure 12 This is a digital photograph of the colored polysaccharide-based edible straw obtained by loading edible pigment molecules in Example 1. Detailed Implementation

[0039] In view of the characteristics of bacterial cellulose and starch and the current status of plastic straws and biodegradable straws on the market, this application provides a polysaccharide-based edible straw composed of bacterial cellulose and starch and its preparation method.

[0040] This application first provides a polysaccharide-based edible straw, the main structure of which is made of a composite hydrogel of starch and bacterial cellulose. The polysaccharide-based edible straw includes: multiple layers of bacterial cellulose, starch layers that act as adhesives between the bacterial cellulose layers through a three-dimensional network, and an edible, water-resistant layer on the surface of the straw. Preferably, its main structure is prepared from a starch-bacterial cellulose hydrogel synthesized by microorganisms. The three-dimensional network interpenetration refers to the process where gelatinized starch fills the pores in the intrinsic three-dimensional network structure formed by bacterial cellulose fibers, and the starch fibers interconnect to form a network structure, resulting in a complete combination of the bacterial cellulose network structure and the starch network structure, exhibiting an overall structure without obvious pores.

[0041] Under field emission scanning electron microscopy, the structure of the polysaccharide-based edible straw according to the present invention is a layered structure with multiple scales. This layered structure consists of macroscopically multi-layered bacterial cellulose layers and microscopically multi-layered structures composed of bacterial cellulose and starch composites. The bacterial cellulose and its internal starch form a three-dimensional interpenetrating network structure, achieving a bonding effect. Simultaneously, it also possesses an ultra-fine physically entangled three-dimensional nanonetwork structure. These unique structures give the straw obtained by the present invention excellent mechanical properties. Moreover, the straw according to the present invention is made entirely from edible raw materials, and the processing does not involve inedible raw materials, making it a novel edible straw.

[0042] In this invention, the term "edible" means that something can be eaten.

[0043] In this invention, the term "multilayer" means having two or more layers.

[0044] In this invention, the terms "layered structure with multiple scales" or "hierarchical layered structure with multiple microscales" both refer to the following: In the straw of this invention, there is a macroscopic bacterial cellulose layer composed of a cellulose membrane formed by starch gelatinization and bacterial cellulose fibers bonded together, with a layer thickness of approximately 20 to 200 micrometers. Simultaneously, the bacterial cellulose layer also contains a more microscopic bacterial cellulose layer microstructure, which is formed during bacterial synthesis of the bacterial cellulose, and the size of this microstructure is only about 200 nanometers to 2 micrometers. That is, the macroscopic bacterial cellulose layer contains microstructures with a microscale size of approximately 200 nanometers to 2 micrometers.

[0045] In this invention, the term "gelatinization" means mixing starch in water and heating it until a certain temperature is reached, at which point the starch granules swell and collapse, forming a viscous, uniform, transparent paste solution.

[0046] In this application, the bacterial cellulose is biosynthesized, preferably synthesized in the presence of one or more selected from Acetobacter xylinum, Agrobacterium, Rhizobium, and Micrococcus occulta.

[0047] On the other hand, this application also provides a method for preparing a polysaccharide-based edible straw, comprising the following steps:

[0048] A) In the process of using bacteria to synthesize bacterial cellulose, starch is introduced to synthesize a composite hydrogel in which starch is uniformly dispersed in bacterial cellulose.

[0049] B) The composite hydrogel obtained in step A) is treated in an edible soda ash aqueous solution with a mass concentration of 0.1%-20%.

[0050] C) The composite hydrogel obtained in step B) is placed in an oven and dried into a film. The oven temperature can range from room temperature to 80°C, preferably 55-65°C, and most preferably about 60°C.

[0051] D) The composite film obtained in step C) is placed in water for thermal crosslinking, preferably in boiling water.

[0052] E) The cross-linked composite film obtained in step D) is wound into a tube to obtain a tube as the main structure;

[0053] F) A water-resistant layer is formed on the surface of the coil obtained in step E), wherein the surface is preferably the inner surface, and more preferably both the inner and outer surfaces.

[0054] In a specific embodiment of the present invention, the preparation method further includes: before step E), removing excess gelatinized starch from the surface of the cross-linked starch-bacterial cellulose composite film obtained in step D) and placing it between food-grade absorbent paper to remove excess surface moisture.

[0055] In a specific embodiment of the present invention, step E) involves rolling a food-grade PTFE rod into a tube and then drying it in an oven to obtain the main structure of a polysaccharide-based edible straw.

[0056] In one specific embodiment of the preparation of polysaccharide-based edible straws in this application, step A) includes the following process:

[0057] A) Prepare a solution of 10-100 g / L of water (solvent) as a base. -1 Glucose, 1-40 g / L -1 Yeast extract, 1-50g / L -1 A solid culture medium composed of agar, prepared using 1 liter of water (solvent) as a standard, consists of 10-100 g / L of agar. -1Glucose, 1-40 g / L -1 Yeast extract, 0.1-10 g / L -1 Citric acid, 0.1-10 g / L -1 Na2HPO4·12H2O and 0.1-10 g L -1 Liquid culture medium composed of KH2PO4. Then solid culture medium, liquid culture medium, and 10-100g L... -1 The dried starch was sterilized in an autoclave at 110-150℃, preferably 120℃, for 5-90 minutes. After sterilization, bacteria that produce bacterial cellulose were inoculated into a solid culture medium, and then fermented continuously at a constant temperature of 25-30℃ for, for example, 4-6 days. The sterilized starch was mixed with a liquid culture medium, and then aerosol-assisted synthesis was used to add the starch-containing liquid culture medium to the growing bacterial cellulose, and growth continued to obtain a composite hydrogel of starch and bacterial cellulose with a thickness of, for example, 3-10 mm, preferably about 5 mm.

[0058] In one specific preparation embodiment, in step B), the mass concentration of the edible soda ash aqueous solution is 0.1%-20%, for example, 10%;

[0059] In one specific preparation embodiment, the crosslinking temperature in step D) is 90-100℃ and the crosslinking time is 5-10min.

[0060] In one specific preparation embodiment, step E) includes: removing excess gelatinized starch from the surface of the cross-linked starch-bacterial cellulose composite film obtained in step D), placing it between dry food-grade absorbent paper to remove some moisture, rolling it into a tube using food-grade PTFE rods, and drying it in an oven to obtain a polysaccharide-based edible straw.

[0061] In one specific preparation embodiment, step F) includes: placing the straw obtained in step E) into molten edible beeswax, coconut oil or palm oil, and quickly removing it to cool naturally, forming an edible water-resistant layer on the surface of the straw.

[0062] In one specific preparation embodiment, the starch is selected from one or more of corn starch, potato starch, sweet potato starch, etc. More preferably, the starch is selected from amylose. Most preferably, the starch is selected from natural corn amylose.

[0063] In one specific preparation embodiment, the synthetic cellulose bacteria in step D) are selected from one or more of Acetobacter xylinum, Agrobacterium, Rhizobium, and Diplococcus.

[0064] In a specific preparation implementation, the composite hydrogel of bacterial cellulose and starch has a thickness of 0.1-3 cm, a length of 3-30 cm, and a width of 3-10 cm.

[0065] For the polysaccharide-based edible straw of this application, the inner diameter ranges from 1 to 100 mm, preferably from 2 to 30 mm, more preferably from 5 to 12 mm; the wall thickness ranges from 0.01 to 20 mm, preferably from 0.1 to 10 mm, more preferably from 0.35 to 3.5 mm.

[0066] In one particularly specific embodiment, the polysaccharide-based edible straw has an outer diameter of 1.0 cm, a length of 10 cm, and a thickness of 0.5 mm.

[0067] In summary, the preparation method of this application provides a polysaccharide-based edible straw made from a biosynthesized starch-bacterial cellulose composite hydrogel. The polysaccharide-based straw possesses a multi-layered structure at multiple microscales. It exhibits an ultra-fine, physically entangled three-dimensional nanonetwork structure, endowing it with excellent mechanical properties and a certain load-bearing capacity. The straw's three-point bending performance exceeds 40 MPa, far surpassing that of traditional plastic and paper straws on the market. The straw is made entirely from edible raw materials, and the processing does not involve the use of inedible materials, making it a novel edible straw. The polysaccharide-based straw provided by this application features high strength, high resistance to deformation, and no microplastic release. In particular, it is not only biodegradable but also safe for consumption, making it a strong competitor to traditional plastic straws and paper straws with poor user experience. In addition, the bacterial cellulose straw provided in this application has excellent loading capacity, capable of loading natural pigment molecules and fragrance molecules to give it ideal color and smell, and can also load natural plant extracts, which are beneficial to health, and load some drug molecules, which can play a certain role in health care and treatment.

[0068] Furthermore, in the preparation of polysaccharide-based edible straws, this application first prepares a composite hydrogel of starch and bacterial cellulose through biosynthesis. Then, the obtained composite hydrogel is treated with an edible soda ash solution. During this treatment, residual culture medium, microorganisms, proteins, and other components are removed by the alkaline soda ash solution, achieving a sterilization effect. Afterward, the treated composite hydrogel is washed with water to remove the internal soda ash solution, and then placed between food-grade absorbent paper to remove some moisture. It is then placed in water for thermal cross-linking treatment, ensuring thorough gelatinization of the internal starch. Excess gelatinized starch on the surface of the bacterial cellulose composite hydrogel is removed, and it is placed between dry food-grade absorbent paper to remove some moisture. It is then rolled into straws on food-grade PTFE rods of different inner diameters and dried in an oven to obtain polysaccharide-based edible straws. After drying, they can be removed from the food-grade PTFE rods. This preparation method disclosed herein avoids the cross-linking of inorganic ions used in existing technologies, thus avoiding the post-cross-linking cleaning process, simplifying the process, saving time, and preventing the residue of inorganic ions and other cross-linking agents from the source. Moreover, the preparation method disclosed herein solves the technical problem in the prior art that starch has low strength, poor water resistance, and is prone to softening in water, changing shape, or even losing its adhesive ability.

[0069] Example

[0070] To further understand the present invention, the following detailed description of the polysaccharide-based edible straw provided by the present invention is provided in conjunction with the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0071] The reagents used in the following examples are all commercially available and were used directly without any special treatment.

[0072] Example 1

[0073] A) Prepare a solution based on 1 liter of water (solvent), using 100 g L as the base. -1 Glucose, 10 g L -1 Yeast extract, 15g L -1 A solid culture medium composed of agar was prepared using 1 liter of water (solvent) as a reference, with each culture containing 100 g of agar as a base. -1 Glucose, 10 g L -1 Yeast extract, 4 g L -1 Citric acid, 8 g L -1 Na2HPO4·12H2O and 4 g L -1 Liquid culture medium composed of KH2PO4. Then solid culture medium, liquid culture medium, and 25g L... -1Dry corn amylose was sterilized in an autoclave at 110-150℃, preferably 120℃, for 20 minutes. After sterilization, Acetobacter xylinum 1.1812, which produces bacterial cellulose, was inoculated into a solid culture medium, and then fermented continuously at a constant temperature of 25-30℃ for about five days. The sterilized corn amylose was mixed with a liquid culture medium, and then aerosol-assisted synthesis was used to add the liquid culture medium containing corn amylose to the growing bacterial cellulose, and growth continued to obtain a composite hydrogel of corn amylose and bacterial cellulose with a thickness of about 5 mm.

[0074] B) The bacterial cellulose hydrogel synthesized in step A) is treated in a 10% (w / w) edible soda ash aqueous solution to remove impurities and then rinsed.

[0075] C) The starch and bacterial cellulose hydrogel obtained in step B) are placed in a 60°C oven and dried to form a composite film;

[0076] D) The starch-bacterial cellulose composite hydrogel obtained in step C) is placed in water for thermal cross-linking at a temperature of 100°C for 8 minutes.

[0077] E) Remove excess gelatinized starch from the surface of the cross-linked starch and bacterial cellulose composite film obtained in step D), place it between food-grade absorbent paper to remove some moisture, and use food-grade PTFE rods to roll it into a tube. Then, dry it in a 60°C oven to obtain a polysaccharide-based edible straw.

[0078] F) Place the straw obtained in step E) into the molten edible beeswax and quickly remove it to cool naturally, forming a water-resistant layer on the surface of the straw;

[0079] Figure 1 The image shows the polysaccharide-based edible straw prepared in this embodiment. All raw materials used are edible, and the straw can be consumed directly after use. Alternatively, if not intended for consumption, it can be discarded into the environment as it is biodegradable and will not cause environmental pollution.

[0080] Figure 2 This is a microscopic photograph of the starch-bacterial cellulose composite hydrogel prepared in this embodiment after supercritical drying. Figure 2 It is known that bacterial cellulose hydrogel has a three-dimensional entangled nanofiber network at the microscopic level, which can provide a good mechanical basis. Starch (the clump-like particles in the figure) is uniformly dispersed in the three-dimensional network of bacterial cellulose. After subsequent heat treatment and gelatinization, the bonding between different layers can be achieved. This composite structure ensures that the straw maintains its structural integrity in various beverages.

[0081] Figure 3The image shows a microscopic photograph of the polysaccharide-based edible straw prepared in Example 1, obtained by field emission scanning electron microscopy. As can be seen from the image, starch combines with cellulose fibers after heat treatment, forming a whole.

[0082] Figure 4 These are microscopic images of the polysaccharide-based edible straws prepared in this embodiment, obtained by field emission scanning electron microscopy. Figure 4 It is known that polysaccharide-based edible straws are composed of layered structures of tens of micrometers in size, and these are layered structures at multiple scales with hierarchical levels.

[0083] Figure 5 This is a larger-scale microscopic image of the tensile cross-section of the polysaccharide-based edible straw prepared in this embodiment, observed under a field emission scanning electron microscope. After heat treatment, the starch gelatinizes and connects with the surrounding bacterial cellulose fibers, achieving a double-network interpenetrating structure. As can be seen from the image, the fully gelatinized starch fills the pores in the intrinsic three-dimensional network structure formed by the bacterial cellulose fibers. The starch fibers interconnect to form a network structure, resulting in a complete integration of the bacterial cellulose network structure and the starch network structure, exhibiting a pore-free overall structure.

[0084] Figure 6 The three-point bending mechanical properties of the polysaccharide-based edible straw prepared in this embodiment at room temperature are compared with those of commercially available disposable straws. The data were obtained by testing on a universal mechanical testing instrument.

[0085] Figure 7 The three-point bending mechanical properties of the polysaccharide-based edible straw prepared in this embodiment at low temperature (0°C) are compared with those of commercially available disposable straws. The data were obtained by testing on a universal mechanical testing instrument.

[0086] Figure 8 The three-point bending mechanical properties of the polysaccharide-based edible straw prepared in this embodiment at high temperature (80°C) are compared with those of commercially available disposable straws. The data were obtained by testing on a universal mechanical testing instrument.

[0087] Figure 9 The compressive mechanical properties of the polysaccharide-based edible straw prepared in this embodiment are compared with those of commercially available disposable straws. The data were obtained by testing on a universal mechanical testing instrument.

[0088] Figure 10 The changes and comparisons of the three-point bending strength of the polysaccharide-based edible straw and paper straw prepared in this embodiment after soaking in water were obtained by testing on a universal mechanical testing instrument.

[0089] Figure 11 The relative activity of human intestinal epithelial cells in the polysaccharide-based edible straw material prepared in this embodiment.

[0090] The mechanical properties of the polysaccharide-based edible straws prepared in this embodiment were tested and compared with those of commercially available paper straws, plastic straws, and PLA straws. Figure 6 As shown in the figure, the polysaccharide-based edible straw prepared in this embodiment has a bending strength of over 40 MPa, and its mechanical properties are more than 6 times higher than those of commercially available paper straws and plastic straws, demonstrating excellent mechanical properties.

[0091] The water resistance of the polysaccharide-based edible straws prepared in this embodiment was compared with that of commercially available paper straws. Figure 10 As shown in the figure, the three-point bending performance of the polysaccharide-based edible straw prepared in this embodiment is much higher than that of paper straws when soaked in water. When the soaking time exceeds 100 minutes, the mechanical properties of the polysaccharide-based edible straw prepared in this embodiment decrease to an edible state, ensuring that the straw has excellent mechanical properties during use and that the mechanical properties decrease after use, making it easy to eat.

[0092] The toxicity of the polysaccharide-based edible straws prepared in this embodiment was tested, such as... Figure 11 As shown in the figure, the polysaccharide-based edible straw prepared in this embodiment has no effect on the activity of human intestinal epithelial cells.

[0093] Example 2

[0094] A) Prepare a solution based on 1 liter of water (solvent), using 100 g L as the base. -1 Glucose, 10 g L -1 Yeast extract, 15g L -1 A solid culture medium composed of agar was prepared using 1 liter of water (solvent) as a reference, with each culture containing 100 g of agar as a base. -1 Glucose, 10 g L -1 Yeast extract, 4 g L -1 Citric acid, 8 g L -1 Na2HPO4·12H2O and 4 g L -1 Liquid culture medium composed of KH2PO4. Then solid culture medium, liquid culture medium, and 25g L... -1 Dry corn amylose was sterilized in an autoclave at 110-150℃, preferably 120℃, for 20 minutes. After sterilization, Acetobacter xylinum 1.1812, which produces bacterial cellulose, was inoculated into a solid culture medium, and then fermented continuously at a constant temperature of 25-30℃ for about five days. The sterilized corn amylose was mixed with a liquid culture medium, and then aerosol-assisted synthesis was used to add the liquid culture medium containing corn amylose to the growing bacterial cellulose, and growth continued to obtain a composite hydrogel of corn amylose and bacterial cellulose with a thickness of about 5 mm.

[0095] B) The biosynthesized bacterial cellulose hydrogel from step A) is treated in a 10% (w / w) edible soda ash aqueous solution to remove impurities and rinse; then it is soaked in a commercial edible pigment solution for 5 hours to allow the pigment molecules to fully penetrate into the three-dimensional network of bacterial cellulose.

[0096] C) The corn amyl starch and bacterial cellulose composite hydrogel obtained in step B) is placed in a 60°C oven and dried to form a composite film;

[0097] D) The corn amylose-bacterial cellulose composite film obtained in step C) is placed in water for thermal cross-linking at a temperature of 100°C for 8 minutes.

[0098] E) Remove excess gelatinized starch from the surface of the cross-linked corn amylose and bacterial cellulose composite film obtained in step D), place it between food-grade absorbent paper to remove some moisture, and use food-grade PTFE rods to roll it into a tube. Then, dry it in a 60°C oven to obtain polysaccharide-based edible straws.

[0099] F) Place the straw obtained in step E) into the molten edible beeswax and quickly remove it to cool naturally, forming a water-resistant layer on the surface of the straw;

[0100] Figure 12 This is a digital photograph of the colored polysaccharide-based edible straws obtained in this embodiment after being loaded with edible pigment molecules. As can be seen from the five colors—red, yellow, blue, green, and orange—the three-dimensional network of bacterial cellulose can effectively retain pigment molecules, thus producing straws of various colors.

[0101] Example 3

[0102] A) Prepare a solution based on 1 liter of water (solvent), using 100 g L as the base. -1 Glucose, 10 g L -1 Yeast extract, 15g L -1 A solid culture medium composed of agar was prepared using 1 liter of water (solvent) as a reference, with each culture containing 100 g of agar as a base. -1 Glucose, 10 g L -1 Yeast extract, 4 g L -1 Citric acid, 8 g L -1 Na2HPO4·12H2O and 4 g L -1 Liquid culture medium composed of KH2PO4. Then solid culture medium, liquid culture medium, and 25g L... -1Dry potato starch was sterilized in an autoclave at 110-150℃, preferably 120℃, for 20 minutes. After sterilization, *Acetobacter xylinum* 1.1812, which produces bacterial cellulose, was inoculated into a solid culture medium, and then fermented continuously at a constant temperature of 25-30℃ for about five days. The sterilized potato starch was mixed with a liquid culture medium, and then aerosol-assisted synthesis was used to add the liquid culture medium containing potato starch to the growing bacterial cellulose, and growth continued to obtain a composite hydrogel of potato starch and bacterial cellulose with a thickness of about 5 mm.

[0103] B) The bacterial cellulose hydrogel synthesized in step A) is treated in a 10% (w / w) edible soda ash aqueous solution to remove impurities and then rinsed.

[0104] C) The starch-bacterial cellulose composite hydrogel obtained in step B) is placed in a 60°C oven and dried to form a composite film;

[0105] D) The starch-bacterial cellulose composite film obtained in step C) is placed in water for thermal cross-linking at a temperature of 100°C for 8 minutes;

[0106] E) Remove excess gelatinized starch from the surface of the cross-linked starch and bacterial cellulose composite film obtained in step D), place it between food-grade absorbent paper to remove some moisture, and use food-grade PTFE rods to roll it into a tube. Then, dry it in a 60°C oven to obtain polysaccharide-based edible straws.

[0107] F) Place the straw obtained in step E) into the molten edible beeswax and quickly remove it to cool naturally, forming a water-resistant layer on the surface of the straw.

[0108] Industrial applicability

[0109] In this invention, the bacterial cellulose used is a biomass-synthesized bacterial cellulose. Due to the ultra-fine, physically intertwined three-dimensional entangled nanonetwork structure of the bacterial cellulose and the three-dimensional interpenetrating network structure formed with starch, the straw obtained by this invention possesses extremely excellent three-point bending strength, resistance to deformation, and compressive strength. Furthermore, the straw described in this invention is made entirely from edible raw materials, and the processing does not involve the use of inedible materials, making it a novel edible straw with promising application prospects.

[0110] The above description of the disclosed embodiments is intended to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the scope of protection of the invention is not limited to the embodiments shown herein, but is broadly interpreted by the appended claims.

Claims

1. A polysaccharide-based edible straw, the main structure of which is made of a composite hydrogel of starch and bacterial cellulose, wherein the polysaccharide-based edible straw comprises: The straw consists of multiple layers of bacterial cellulose, a starch layer that acts as a binder between the layers of bacterial cellulose through a three-dimensional network, and an edible, water-resistant layer on the surface of the straw.

2. The polysaccharide-based edible straw according to claim 1, wherein, The thickness of a single layer of the multi-layered bacterial cellulose layer is 20-200 μm.

3. The polysaccharide-based edible straw according to claim 1, wherein, The structure of the sugar-based edible straw exhibits a layered structure at multiple scales, including: a macroscopic bacterial cellulose layer composed of a cellulose membrane formed by starch gelatinization and bacterial cellulose fibers bonded together, and a microstructure formed when bacteria synthesize the bacterial cellulose, wherein the size of the microstructure is 200 nanometers to 2 micrometers.

4. The polysaccharide-based edible straw according to claim 1, wherein, The thickness of the composite hydrogel is 0.1-3 cm.

5. The polysaccharide-based edible straw according to claim 1, wherein, The edible, water-resistant layer is formed from at least one layer selected from edible beeswax, coconut oil, or palm oil.

6. The polysaccharide-based edible straw according to claim 1, wherein, The straws include colored straws.

7. A method for preparing a polysaccharide-based edible straw according to any one of claims 1-6, the method comprising the following steps: A) In the process of using bacteria to synthesize bacterial cellulose, starch is introduced to synthesize a composite hydrogel in which starch is uniformly dispersed in bacterial cellulose. B) The composite hydrogel obtained in step A) is treated in an edible soda ash aqueous solution to obtain an alkali-treated composite hydrogel. C) The alkali-treated composite hydrogel obtained in step B) is dried at room temperature to 80°C to form a film; D) The film obtained in step C) is placed in hot water for thermal crosslinking to obtain a crosslinked composite film; E) The cross-linked composite film obtained in step D) is wound into a tube to obtain a tube as the main structure; F) A water-resistant layer is formed on the surface of the rolled tube obtained in step E) to obtain a polysaccharide-based edible straw.

8. The method according to claim 7, wherein, The bacteria used to synthesize bacterial cellulose are selected from one or more of Acetobacter xylinum, Agrobacterium, Rhizobium, and Diplococcus.

9. The method according to claim 7, wherein, Step A) includes the following process: Using 1 liter of water as a base, prepare a solution containing 10-100 g / L of water. -1 Glucose, 1-40 g / L -1 Yeast extract, 1-50g / L -1 Solid culture medium composed of agar, with 1 liter of water as a reference, is prepared to contain 10-100 g / L of agar. -1 Glucose, 1-40 g / L -1 Yeast extract, 0.1-10 g / L -1 Citric acid, 0.1-10 g / L -1 Na2HPO4·12H2O and 0.1-10 g L -1 A liquid culture medium composed of KH2PO4 was then added, along with solid culture medium, liquid culture medium, and 10-100 g L... -1 The dried starch was sterilized in an autoclave at 110-150℃ for 5-90 minutes. After sterilization, the bacteria that produce bacterial cellulose were inoculated into a solid culture medium. After continuous fermentation at a constant temperature of 25-30℃, the sterilized starch was mixed with a liquid culture medium. Then, the liquid culture medium containing starch was added to the growing bacterial cellulose using aerosol-assisted synthesis to obtain a composite hydrogel.

10. The method according to claim 7, wherein, The thermal crosslinking temperature in step D) is 90-100℃, and the crosslinking time is 5-10 min.

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