Starch physical modification method based on micro-nano bubble technology

Abstract

The invention discloses a method for modifying starch. According to the method, starch is physically modified by adopting a micro-nano bubble technology. The prepared modified starch is free of chemical component addition, safe and environmentally friendly, the microstructure, FTIR spectrum, crystallinity, expansibility, gelatinization temperature and other aspects are changed, the functional characteristics of the starch in food and non-food products are enhanced, and the application range of the starch is widened.

Description

Technical Field

[0001] This invention belongs to the field of food engineering, specifically, it relates to a method for physical modification of starch based on micro-nano bubble technology and a modified starch. Background Technology

[0002] Starch is an inexpensive, renewable, and biodegradable polymer available from a variety of sources, including grains, tubers, legumes, fruits, leaves, and roots. It is a primary energy source, essential in a wide range of foods, contributing to health and supporting physiological functions. However, unmodified forms of natural starch have significant limitations in practical applications, primarily due to several factors such as poor shear and thermal stability, high gelatinization temperature, pronounced retrogradation tendency, low flowability, poor slurry transparency, and significant gel turbidity. These drawbacks limit the applicability of natural starch to certain food processing and industrial applications, highlighting the necessity of starch modification. Modified starch offers numerous advantages, including improved functionality, better texture, greater stability, more versatile product applications, increased sustainability, and cost-effectiveness. Starch is typically modified through physical, chemical, and specific enzymatic methods. Among these methods, physical modification is widely favored because it can alter starch properties without the addition of chemical reagents. Using physical methods for modification avoids potential problems associated with chemical residues or environmental impacts, and the use of physically modified starch also meets the growing demand in the food and industrial sectors for clean, natural and environmentally friendly ingredients.

[0003] Micro-nano gas bubbles (MNBs) are tiny gas-dispersed particles in a solution, ranging in diameter from tens of nanometers to tens of micrometers. Compared to ordinary bubbles, MNBs, due to their small size, are more susceptible to the Brownian motion of solution molecules, exhibit strong stability, long existence time in solution, a negatively charged gas-liquid interface, and the ability to form free radicals during bubble collapse. These physicochemical properties have led to their widespread application in environmental pollution control, agriculture, materials science, and medicine. In recent years, with a deeper understanding of MNBs, their research and application in the food industry have also increased. Micro-nano gas bubble (MNB) technology represents cutting-edge green innovation in the food industry. MNBs are gas-filled microbubbles or nanoscale bubbles. Microbubbles (MBs) and nanobubbles (NBs) are classified according to their size: traditional bubbles range from 600 to 2500 μm, large bubbles from 1 to 10 mm, fine bubbles from 10 to 15 μm, and superbubbles smaller than 200 nm. When the pressure suddenly drops below a critical level, microbubbles (MNBs) form, inducing a phase transition and creating gas-filled bubble chambers. In recent years, with a deeper understanding of micro- and nanobubbles, their research and application in the food industry have gradually increased. Compared to traditional chemical and enzymatic methods, modifying starch using cavitation-assisted micro- and nanobubbles eliminates the need for adding other components to the starch raw material. The modification process is completed solely through changes in gas and pressure, avoiding potential health and environmental risks associated with adding chemical components, thus meeting current industrial demands for clean and environmentally friendly production. Compared to other physical methods, this method is simple to operate and easy to adjust. Furthermore, compared to traditional methods, this method significantly reduces the production cost and operational requirements of modified starch, naturally meeting the needs of large-scale, multi-batch production in actual manufacturing, and possesses extremely high practical application value. Summary of the Invention

[0004] Currently, there are no reports on the application of micro-nano technology in starch modification. To address the aforementioned problems in existing starch modification processes and starch products, we have developed a method for physical modification of starches from different plant sources using hydrodynamic cavitation-assisted microbubbles. The modified starch prepared not only has food safety but also exhibits superior changes compared to natural starch in terms of starch crystallinity, structure, and gelatinization, thus improving taste and quality. This demonstrates that micro-nano technology can effectively modify natural starch, greatly expanding its application in the food industry. Specifically, this invention includes the following technical solutions.

[0005] The first aspect of this invention provides a method for modifying starch, comprising the following steps: physically modifying starch using micro-nano gas bubbles (MNBs or MNBs). This MNB technology belongs to hydrodynamic cavitation-assisted microbubble technology (HCAM), and when used for modifying starch, it is called microbubble-assisted starch modification technology (MASM).

[0006] The starch mentioned above can be selected from the following group of types: potato starch, wheat starch, corn starch, rice starch, sweet potato starch, tapioca starch, and soybean starch. Preferably, the starch is selected from the following group of types: potato starch, wheat starch, corn starch, and rice starch.

[0007] Preferably, the above-mentioned micro-nano bubble technology uses nitrogen (N2), carbon dioxide (CO2) gas or air to form bubbles, and more preferably uses nitrogen (N2) to form micro-nano bubbles.

[0008] In one embodiment, during the modification treatment of starch, i.e., hydrodynamic cavitation treatment, no enzymes such as amylase or chemical reagents such as peroxides are added to the starch or the water used to disperse the starch.

[0009] Preferably, after treatment with the micro / nano bubble technology, the modified starch undergoes the following physicochemical property changes compared to the untreated starch (e.g., natural starch):

[0010] A. The Fourier transform infrared (FTIR) spectrum changes between the absorption bands of 500-1550 cm⁻¹ and 3000-3550 cm⁻¹; in the 3300-3600 cm⁻¹ range... -1 The absorbance decreases by 5% or more, preferably 10% or more, preferably 15% or more, preferably 20% or more, preferably 25% or more, and more preferably 30% or more within the specified range; R1047 / 1022cm -1 The reduction in belt ratio is more than 5%, preferably more than 10%, preferably more than 15%, preferably more than 20%, preferably more than 25%, and more preferably more than 30%.

[0011] B. The crystallinity decreases by more than 5%, preferably more than 10%, more than 15%, more than 20%, more than 25%, and more than 30% as characterized by X-ray diffraction patterns, with the degree of crystallinity change in the amorphous region being greater than that in the crystalline region;

[0012] C. When observed using a scanning electron microscope (SEM), the microstructure undergoes the following changes: the indentations on the particle surface expand, creating depressions, forming pores, surface pitting, fractures and cracks, and / or mechanical damage to the particle surface.

[0013] D. The expansion force is increased by 10% or more, preferably 20% or more, preferably 30% or more, preferably 40% or more, preferably 50% or more, more preferably 60% or more; and / or

[0014] E. The gelatinization temperature (including one or more of the starting temperature (To), peak temperature (Tp), and ending temperature (Tc)) is reduced by more than 5%, preferably more than 10%, more preferably more than 15%, more preferably more than 20%, more preferably more than 25%, and more preferably more than 30%.

[0015] In the expansion force experiment, the formula for calculating the expansion force is:

[0016] Expansion force (g / g) = Weight of residual sediment ÷ (Weight of dry starch - Weight of dissolved starch).

[0017] It should be understood that in this article, when describing numerical characteristics, the terms “about,” “approximately,” or “around” mean that the expressed number may have an error range or fluctuation range of ±10%, ±8%, ±6%, ±4%, or ±2%.

[0018] In one embodiment, the above-mentioned micro / nano bubble technology includes the following steps:

[0019] (1) Disperse starch in water at a ratio of 5-35% w / w, preferably 10-30% w / w, preferably 10-25% w / w, preferably 15-25% w / w, for example about 20% w / w, to form a starch dispersion;

[0020] (2) Using a micro-nano bubble forming device, gaseous micro-nano bubbles with a diameter of 10nm-100μm, preferably 20nm-80μm, preferably 30nm-70μm, more preferably 40nm-60μm, more preferably 50nm-50μm are introduced into the starch dispersion, and the micro-nano bubbles are kept in the starch dispersion for a time that can effectively change the starch molecular structure to reach the predetermined physicochemical index, for example, the hydrodynamic cavitation treatment lasts for 5-30min, preferably 7-20min, preferably 8-15min, for example, about 10min, to obtain the hydrodynamic cavitation treatment liquid;

[0021] (3) Centrifuge the hydrodynamic cavitation treatment fluid, discard the supernatant, and obtain modified starch sediment; or

[0022] Hydrodynamic cavitation treatment fluid was directly spray-dried to obtain hydrodynamic cavitation assisted microbubble (HCAM) modified starch, i.e., modified starch;

[0023] (4) The modified starch sediment in step (3) is dried, for example at 30-50°C, preferably 35-45°C, preferably about 40°C, to obtain hydrodynamic cavitation assisted microbubble (HCAM) modified starch, i.e., modified starch.

[0024] Optionally, the micro-nano bubble forming device in step (2) is a fluid dynamics cavitation device, i.e., a micro-nano bubble generator.

[0025] Optionally, in step (2) above, a homogenizer is used to pass the formed micro-nano bubbles into the starch dispersion at a speed of about 8000 rpm or more, preferably 9000 rpm or more, preferably 10000 rpm or more, and more preferably 11000 rpm.

[0026] A second aspect of the present invention provides a modified starch prepared by the method described above.

[0027] Preferably, the modified starch described above can be used in food manufacturing and the manufacture of industrial products such as adhesives.

[0028] The microbubble-assisted starch modification technology (MASM) developed in this invention is a practical, cost-effective, and efficient solution for starch modification. The resulting modified starch products are free of added chemicals, safe, and environmentally friendly. This modified starch exhibits superior changes compared to natural starch in terms of crystallinity, structure, and gelatinization temperature. Both the changes in crystallinity and the reduction in gelatinization temperature contribute to improving the taste and quality of edible products made from starch, while also enhancing the performance of starch in food processing. Furthermore, the altered microstructure significantly improves the rheological properties of starch, enhancing its application prospects in the food packaging and building adhesive industries. Attached Figure Description

[0029] Figure 1 The results show the SEM and RVA analyses of natural and MASM-based potato (A), wheat (B), maize (C), and rice starch (D).

[0030] Figure 2 X-ray spectra of natural and MASM-based potato (A), wheat (B), corn (C), and rice starch (D) are shown.

[0031] Figure 3 FTIR spectra of natural starch and MASM from potato (A), wheat (B), corn (C), and rice starch (D) are shown. Detailed Implementation

[0032] Natural starch has several drawbacks, such as poor shear and thermal stability, high gelatinization temperature, easy retrogradation, low fluidity, poor slurry transparency, and high gel turbidity, which limit its application in certain food processing and industrial applications. This invention utilizes hydrodynamic cavitation to generate micro-nano bubbles with different gases, achieving a safe and environmentally friendly modified starch through this physical method without the use of any chemical additives or enzymes, thus expanding the application prospects of starch.

[0033] After natural starch is treated using hydrodynamic cavitation technology, significant changes occur in its microstructure, FTIR spectrum, crystallinity, swelling power, and / or gelatinization temperature. Some physicochemical indicators show significant changes, enhancing the application value of starch. These changes are manifested in increased microstructural fragmentation / breakage / loosening observed by SEM, improved swelling power, and improved FTIR spectra in the 3300-3600 cm⁻¹ range. -1 The absorbance decreases, the crystallinity decreases, and / or the gelatinization temperature decreases within the range.

[0034] In the description of the technical solutions of this invention, the term "and / or" used in terms such as "A and / or B" or "A and / or B" is intended to include both A and B; A or B; A (alone); and B (alone). Similarly, the term "and / or" used in phrases such as "A, B, and / or C" is intended to cover each of the following embodiments: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); C (alone).

[0035] As used herein, the terms “(expansion force) increase,” “enhancement,” or “increase” can mean an increase of at least 5% relative to a reference level (such as natural starch), for example, an increase of at least about 5%, at least about 10%, at least about 15%, at least about 20%, or at least about 30%, or at least about 40%, or at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, or at least about 90%, or an increase of up to and including 100%, or any increase between 10% and 100%.

[0036] Similarly, the terms “(gelatinization temperature) decrease,” “drop,” or “reduction” can mean a reduction of at least 5% relative to a reference level (such as natural starch), for example, a reduction of at least about 5%, at least about 10%, at least about 15%, at least about 20%, or at least about 30%, or at least about 40%, or at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, or at least about 90%, or up to and including a reduction of 100%, or any reduction between 10% and 100%.

[0037] This study investigated the effects of hydrodynamic cavitation on starch crystallinity, structure, and thermal and gelatinization behavior. It also examined the starch modification effects of different gases. Using potato, wheat, corn, and rice starches as raw materials, modified starches were prepared by generating micro / nanobubbles using air, N2, and CO2. After obtaining the products, comprehensive physicochemical property testing was conducted to identify the best-performing modified starch and its preparation method. Nitrogen (N2) was found to produce the best overall results, demonstrating its significant potential in modifying various plant starches and making it highly suitable for large-scale food processing. Furthermore, the study showed that hydrodynamic cavitation can enhance the functional properties of starch in both food and non-food products, broadening its application range.

[0038] The method of this invention has a significant effect on the modification of natural starch. The use of hydrodynamic cavitation-assisted microbubble generation for the physical modification of starches from different plant sources is unprecedented. This invention is the first to employ this technology for the physical modification of starch, and the results show that the starch structure is significantly altered, and various defects are significantly improved. For starches modified using three different gas sources with assisted cavitation, it was found that using N2 and CO2 was more effective than using air; the modified starches obtained using N2 and CO2 had better performance in various indicators than those obtained using air. After modification with gas microbubble assistance, the microstructure of different plant starches was significantly altered, such as enlarged indentations on the particle surface, the formation of pits, pores, surface pitting, fractures and cracks, and various forms of mechanical damage to the particle surface. This change in microstructure will greatly improve the rheological properties of starch, enhancing its application prospects in biodegradable plastics, packaging materials, adhesives, and the food industry. Regarding crystallinity, compared with natural starch, the treated starch showed a relative decrease in crystallinity, and the amorphous regions were more affected than the crystalline regions. Furthermore, significant changes were observed in the FTIR spectra between 500-1550 cm⁻¹ and 3000-3550 cm⁻¹, indicating possible disruption or damage to the starch polymer structure. The treated starch exhibited a significantly increased swelling capacity compared to its natural counterpart, with the degree of swelling depending on the type of gas used during treatment. Treatment also significantly reduced the gelatinization initiation temperature of the starch. Both the alteration in crystallinity and the reduction in gelatinization temperature greatly contribute to improving the taste and quality of edible products made from starch, while also enhancing the performance of starch in food processing.

[0039] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0040] Example

[0041] In embodiments of the present invention, unless otherwise specified, the experimental operating temperature generally refers to room temperature (10-30°C).

[0042] This article involves the addition amount, content and concentration of various substances. Unless otherwise specified, the percentage content mentioned refers to the weight percentage.

[0043] In this article, "solution" or "liquid" generally refers to an aqueous solution, with water usually being the primary solvent / dispersant, which is easily understood by those skilled in the art.

[0044] Example 1: Starch Modification and Physicochemical Property Investigation

[0045] I. Experimental Materials

[0046] 1. Plant materials:

[0047] Samples of potato, wheat, rice, and corn starch.

[0048] 2. Reagent kit

[0049] Amylose / Amylopectin Assay Kit.

[0050] 3. Instruments

[0051] Scanning electron microscope, Vertex 70 instrument (FT-IR spectroscopy), X-ray diffractometer, rapid viscosity analyzer (RVA), differential scanning calorimetry (DSC) instrument equipped with STAR software.

[0052] II. Experimental Procedure

[0053] 1. Add the starch dispersion (20% w / w) to an 800 mL beaker;

[0054] 2. Microbubble dispersions were prepared by fluid dynamic cavitation. N2, CO2 and air at a flow rate of 16 L / min were introduced into a beaker at a speed of 11000 rpm for 10 min using a homogenizer.

[0055] 3. Centrifuge the sample at 3500 rpm for 3 min;

[0056] 4. Dry at 40℃ for 24 hours, and then use the dried sample for later use.

[0057] 5. SEM microstructure analysis

[0058] To minimize the charge effect caused by the electron beam, 0.1 g of each sample was placed on a SEM copper disk coated with gold powder and fixed with double-sided tape. The microstructure of the starch samples was analyzed using a scanning electron microscope (SEM, Leica Cambridge, UK) at 20 kV.

[0059] 6. Fourier Transform Infrared Spectroscopy (FTIR)

[0060] The spectra of starch samples were obtained using a 1% (w / w) potassium bromide disk technique, with a wavelength range of 400–4000 cm⁻¹. -1 The resolution is 2cm. -1 .

[0061] 7. X-ray diffraction analysis.

[0062] 8. Analysis of Expansion Force Experiment

[0063] Weigh 2.0 g (dry basis) of the sample into a 50 mL centrifuge tube. Quickly add 30 mL of distilled water using a rapid separatory tube, immediately cap the tube, and thoroughly mix the contents using a vortex mixer to prevent starch clumping. Place the tube in a water bath at 85 ± 0.5 °C for 30 min to cool the slurry to room temperature. Centrifuge the slurry at 2500 g for 10 min, carefully pour the supernatant into an evaporating dish, and dry at 105 °C for 5 h. Record the weight of the dried supernatant and residue. Swelling force (SP) calculation formula:

[0064] Expansion force (g / g) = Weight of residual sediment ÷ (Weight of dry starch - Weight of dissolved starch).

[0065] 9. Viscosity and Thermal Properties Analysis

[0066] The gelatinization characteristics of natural and hydrolyzed starches were determined using a rapid viscosity analyzer (RVA). Differential scanning calorimetry (DSC) instruments equipped with STAR software were used to analyze the gelatinization characteristics of natural and hydrolyzed starches, and the changes in the end-of-gelatinization temperature (Tc), enthalpy (ΔH in J / g dry starch), onset temperature (To), and peak temperature (Tp) were determined based on the DSC curves.

[0067] 10. Statistical Analysis

[0068] All experiments were performed in triplicate, and the mean and standard deviation were calculated. Statistical analysis was performed using SPSS 22 software, and Duncan's multiple range test was used to assess the significance of differences between means (P ≤ 0.05).

[0069] Results and Discussion

[0070] 1. The effect of microbubbles on starch morphology

[0071] Starch from different plant sources exhibits different morphologies, including oval, ellipsoidal, spherical, smooth, angular, and lenticular. Scanning electron microscopy analysis shows that corn, rice, and wheat starch granules appear relatively rough compared to the smoother potato starch granules. Figure 1As shown, corn starch granules are spherical, angular, and polyhedral in shape, with additional surface indentations, pinholes, and equatorial grooves or channels. Rice starch granules are pentagonal and angular, often clustering into compact spherical bundles or clusters, also known as complex granules, occupying most of the central space within the rice endosperm cells. The average size of different starch granules also varies, ranging from 0.1 to 200 μm in microscopic size. Under natural conditions, small potato starch granules are between 1 and 20 μm, while large starch granules are between 20 and 110 μm; corn starch granules range from 1 to 7 μm for small granules and 15 to 20 μm for larger granules; rice starch granules are typically between 3 and 5 μm; wheat starch contains two different types of granules: large type A granules, usually disc-shaped or lenticular, with a diameter of 10 to 35 μm, and small type B granules, roughly spherical or polygonal, with a diameter of 1 to 10 μm.

[0072] like Figure 1 As shown, the present invention employs microbubble-assisted starch modification technology (MASM) to induce significant changes in the structure of starch granules. The structural changes in starch granules from different plant sources mainly include: (1) enlargement of indentations on the granule surface; (2) appearance of depressions on the granule surface; (3) formation of pores, surface pitting, fractures, cracks, and various forms of mechanical damage on the granule surface; and (4) disruption of the connections between and within granules, leading to the disintegration of granule aggregates and breakage of polymer chains.

[0073] A comparison of the effects of different gases on starch structure during hydrodynamic cavitation revealed that nitrogen (N2) had the most significant effect, followed by carbon dioxide (CO2), while air had almost no effect. Hydrodynamic cavitation had similar effects on corn starch granules and rice starch, but its effects on potato and wheat starch differed significantly. Natural corn and rice starch contain internal pores and channels (…). Figure 1 After microbubble pretreatment, these voids and channels expand. This internal corrosion of the microbubbles further leads to the formation of more tiny pores and disintegration of starch granules, making the randomly distributed pinholes on the surface of rice and corn starch granules more noticeable. In contrast, the effects on corn and rice starch are different.

[0074] Potato starch and wheat starch are more susceptible to crack formation mechanisms, forming a "surface erosion" pattern through external corrosion.

[0075] 2. Crystallinity analysis

[0076] X-ray diffraction patterns were used to analyze the long-range crystal structure and relative crystallinity of starch samples. Figure 2X-ray diffraction patterns of modified and natural starches are shown. After microbubble-assisted starch modification (MAPSM), the relative crystallinity of natural potato starch (NPS) decreased from 38.4% to 29.3%. MAPSM using CO2 and N2 further reduced the relative crystallinity to 22.8% and 14.5%, respectively. Similar trends were observed for wheat, corn, and rice starches. After air bubbling, the relative crystallinity decreased from 34.2% (NWS), 40.1% (NCS), and 33.6% (NRS) to 31.8% (MAWSM), 32.4% (MACSM), and 29.7% (MARSM), respectively; after CO2 bubbling, the relative crystallinity decreased to 24.3% (MAWSM), 30.5% (MACSM), and 26.7% (MARSM), respectively. After N2 bubbling, the crystallinity decreased to 21.2% (MAWSM), 29.6% (MACSM), and 22.9% (MARSM), respectively. The amorphous portion of the granules was more significantly affected than the crystalline portion. Changes in starch crystallinity help improve the taste and quality of starch-based edible products, and the use of microbubble-assisted starch modification technology (MASM) will further expand the application of starch in the food and processing industries.

[0077] 3. Spectral analysis

[0078] Starch typically appears in Fourier transform infrared (FTIR) spectra from 1150 to 900 cm⁻¹. -1 Absorption bands are displayed within the range, corresponding to the bending and stretching of CO, CC, and COH bonds. At 1160 cm⁻¹... -1 1082cm -1 and 993cm -1 A distinct peak appears at 840 cm⁻¹, indicating CO stretching. -1 and 1077cm -1 The band at this location is related to the stretching of the CH2-O-CH2 group. Furthermore, at 1381 cm⁻¹... -1 The characteristic peak of CH symmetry bending appears at 2358 cm⁻¹. -1 An O=C=O stretching peak appears at 2900 to 3000 cm⁻¹. -1 CH tensile vibration peaks appear within the range of 1200-900 cm⁻¹. Previous studies have shown that... -1 The range of bands exhibits a particularly responsive change in starch structure. For example... Figure 3 As shown, the plant starch of all MASMs is in the range of 500-1550 cm⁻¹ -1 and 3000-3550cm -1Significant changes occurred in the FTIR spectra between 500-1550 cm⁻¹. These changes indicate possible disruption or damage to the starch polymer structure, and alterations in the CO tensile vibrations associated with the COC and COH bonds. -1 This region typically represents bending and stretching vibrations associated with the polysaccharide backbone; significant changes here reflect potential depolymerization or conformational changes in starch. Meanwhile, the 3000-3550 cm⁻¹ region... -1 The region primarily highlights the stretching vibration of OH groups. This spectral change may indicate starch hydrolysis or reactions involving other components, leading to changes in CO bonds. In this study, compared to natural starch, MASM-treated starch showed changes in the 3000-3550 cm⁻¹ region. -1 The absorbance decreases within this range. Potato and wheat starches undergo more structural changes than corn starch after MASM pretreatment. This spectral region is associated with complex stretching vibrations of OH bonds and is influenced by free hydrogen bonds, intramolecular hydrogen bonds, and hydrogen bonds between intermolecular hydroxyl groups. The absorption band is in the 3300-3600 cm⁻¹ range. -1 Approximately 2900cm -1 1150cm -1 and 1000-1100cm -1 The variations within this range indicate that all OH, CH, COC, and CO functional groups in starch were modified. At 1022 cm⁻¹ -1 and 1047cm -1 The IR absorption bands at these locations correspond to amorphous and crystalline structures, respectively, providing information about hydrogen bond strength and the stability of the double-helix structure in the material. R = 1047 / 1022 cm⁻¹ -1 The band ratio represents the proportion of crystalline to amorphous structures. After MASM treatment, R = 1047 / 1022 cm⁻¹ -1 The proportions decreased from 1.112 for natural potato starch (NPS), 1.281 for natural corn starch (NCS), 0.689 for natural rice starch (NRS), and 0.834 for natural wheat starch (NWS) to 1.031–1.065 (MAPSM), 1.229–1.265 (MACSM), 0.759–0.802 (MAWSM), and 0.641–0.667 (MARSM), respectively. These results are consistent with X-ray analysis and swelling force measurements, indicating that MASM significantly reduces the crystallinity of starch granules, ultimately leading to the formation of cracks and fissures, new fragments, and the disintegration of granular aggregates.

[0079] 4. Expansion force

[0080] Table 1 lists the swelling power of natural starch and MASM-treated potato, wheat, corn, and rice starches. The swelling capacity of starch granules is influenced by various factors, including amylose content, the ratio of amylose to amylopectin, the molecular structure of amylopectin, the degree and length of branching, phosphorus content, and crystallinity loss. For natural starches, the swelling power of different starches is: potato > wheat > corn > rice. MASM-treated starches show increased swelling power compared to their natural counterparts, with the degree of swelling depending on the type of gas used in the MASM process. Among all starches, the trend in swelling power is: N2 > CO2 > air. This increase in swelling power is likely due to the disruption, disorder, and reduced crystallinity of starch granules. The chemical and physical damage to starch granules may enhance water permeability and promote water binding. This is achieved through the interaction between ROS and the amylose and amylopectin components, as well as the formation of hydrogen bonds, thereby promoting further hydration. Changes in swelling power reflect alterations in starch swelling capacity and have a positive impact on starch gel strength, starch digestibility, and other indicators.

[0081] Table 1. Swelling force (g / g) and 1047 / 1022 cm⁻¹ of different natural starches and MASM-treated starches -1 ratio

[0082]

[0083] 5. Gelatinization and thermal properties

[0084] The Rapid Viscosity Analyzer (RVA) measures viscosity parameters based on temperature and time, capturing gelatinization behavior in three distinct stages. Factors influencing gelatinization properties include the proportion of amorphous starch, the length of amylopectin chains, and the leaching and swelling behavior of amylose. Figure 1Table 2 shows the gelatinization curves of natural and hydrodynamic cavitation-assisted microbubble (HCAM) modified starches. HCAM treatment significantly reduced the gelatinization onset temperature, indicating that starch granules began to swell earlier during heating. N2 and CO2 gases effectively disrupted the molecular structure of starch, including intramolecular and intermolecular hydrogen bonds. With increasing temperature, starch chains gained greater freedom, allowing water molecules to more easily penetrate the pregelatinized granules, leading to the leakage of amylose molecules from the granule interior. The ability of HCAM to disrupt intramolecular hydrogen bonds in starch chains facilitated this process, resulting in earlier gelatinization and a lower gelatinization temperature. The effect of HCAM on starch granules also led to an increase in paste viscosity, primarily due to accelerated starch granule swelling, starch chain breakage, and increased leaching of polysaccharides (mainly amylose) into the surrounding environment, resulting in increased paste rigidity. Compared to natural starch, hydrodynamically cavitation-treated starch granules exhibited pits and pores on their surface, enhancing water permeability and leading to more significant swelling and an increase in peak viscosity (PV). Furthermore, HCAM treatment reduces crystallinity, leading to amorphization of the short-range ordered structure and disrupting the helical structure within starch granules. These changes may result in increased PV, as disordered starch structures are typically more resistant to shear and heating. When starch molecules are treated with HCAM, intramolecular and intermolecular crosslinks of the polymer chains are disrupted. Water molecules then bind to the hydroxyl groups on both amylose and amylopectin molecules via hydrogen bonds, further enhancing starch swelling and increasing paste viscosity. The PV and final viscosity (FV) of starch increased after all gas modifications, in the order of effect: N2 > CO2 > air.

[0085] The effects of hydrodynamic cavitation of different gases on starch gelatinization temperature (including onset temperature (To), peak temperature (Tp), and end temperature (Tc)) and enthalpy change (ΔH) were evaluated using differential scanning calorimetry (DSC). Onset temperature (To) marks the beginning of the decomposition of the internal structure of the granules, releasing polysaccharides such as amylose into the suspension medium. Peak temperature (Tp) represents the mass of the crystallites and is related to the length of the double helix. Enthalpy change (ΔH) reflects the degree of loss of molecular order in the starch matrix. As shown in Table 2, the To, Tc, and Tp of hydrodynamic cavitation-assisted microbubble (HCAM) treated starch (MASM) were significantly lower (P < 0.05) than their natural counterparts. These changes can be attributed to the disruption of the ordered double helix structure by HCAM and the subsequent reduction in crystallinity, thus lowering the decomposition temperature. The decrease in To corresponds to the melting of the weakest crystallites by hydrodynamic cavitation. The ΔH value indicates the disruption of the double helix structure, not just the loss of crystalline order. The decrease in ΔH for MASM indicates that the double helix of the starch granules is disrupted in both amorphous and crystalline regions.

[0086] Table 2. Gelatinization characteristics (RVA determination) and thermodynamic characteristics (DSC determination) of natural starch and MASM-treated starch

[0087]

[0088]

[0089] in conclusion:

[0090] Hydrodynamic cavitation technology offers a more energy-efficient alternative to acoustic and traditional methods. Beyond its energy advantages, this technology provides a practical and cost-effective solution for industrial applications. This study investigated the effects of hydrodynamic cavitation on the crystallinity, structure, and thermal properties of starch, analyzing the influence of different gases with varying characteristics on these properties. Through this method, we obtained environmentally friendly modified starch without any added chemicals, exhibiting superior changes in crystallinity, structure, and gelatinization compared to natural starch. Both the altered crystallinity and the reduced gelatinization temperature contribute to improved taste and quality of edible products made from starch, while enhancing starch performance in food processing. Furthermore, the altered microstructure significantly improves the rheological properties of starch, enhancing its application prospects in the food packaging and building adhesive industries. Hydrodynamic cavitation technology shows considerable potential in modifying various plant starches and is well-suited for large-scale food processing. In addition, hydrodynamic cavitation can enhance the functional properties of starch in both food and non-food products, broadening its application range.

[0091] It should be noted that the above embodiments are only used to explain the inventive concept of the present invention, and are not intended to limit the scope of protection of the claims of the present invention. Any non-substantial modifications made to the present invention using this concept should fall within the protection scope of the present invention.

[0092] References:

[0093] E. Abedi, K. Pourmohammadi, M. Jahromi, M. Niakousari, L. Torri, The Effect of Ultrasonic Probe Size for Effective Ultrasound-Assisted Pregelatinized Starch, Food Bioprocess Technol. 12 (2019). https: / / doi.org / 10.1007 / s11947-019-02347-2.

[0094] E.Abedi,M.Sayadi,K.Pourmohammadi,Effect of freezing-thawing pre-treatment on enzymatic modification of corn and potato starch treated withactivatedα-amylase:Investigation of functional properties,Food Hydrocoll.(2022)107676.

[0095] A.M.Amini,S.M.A.Razavi,S.A.Mortazavi,Morphological,physicochemical,and viscoelastic properties of sonicated corn starch,Carbohydr.Polym.122(2015)282-292.

[0096] F.Zhu,Impact of ultrasound on structure,physicochemical properties,modifications,and applications of starch,Trends Food Sci.Technol.43(2015)1-17.https: / / doi.org / https: / / doi.org / 10.1016 / j.tifs.2014.12.008.

[0097] H.Wang,K.Xu,Y.Ma,Y.Liang,H.Zhang,L.Chen,Impact of ultrasonication onthe aggregation structure and physicochemical characteristics of sweet potatostarch,Ultrason.Sonochem.63(2020)104868.

Claims

1. A method for modifying starch, characterized in that, Includes the following steps: Starch was physically modified using micro-nano bubble technology.

2. The method as described in claim 1, characterized in that, The starch is selected from the following group of types: potato starch, wheat starch, corn starch, and rice starch.

3. The method as described in claim 1, characterized in that, The micro-nano bubble technology uses nitrogen (N2), carbon dioxide (CO2) gas or air to form bubbles, with nitrogen (N2) being the preferred gas.

4. The method as described in claim 1, characterized in that, No enzymes or chemical reagents are added to the starch or water during the modification process.

5. The method as described in claim 1, characterized in that, After treatment with the aforementioned micro / nano bubble technology, the modified starch undergoes the following changes in physicochemical properties compared to the untreated starch: A. The Fourier transform infrared (FTIR) spectrum changes between the absorption bands of 500-1550 cm⁻¹ and 3000-3550 cm⁻¹; in the 3300-3600 cm⁻¹ range... -1 The absorbance decreases by 5% or more, preferably 10% or more, preferably 15% or more, preferably 20% or more, preferably 25% or more, and more preferably 30% or more within the specified range; R1047 / 1022cm -1 The reduction in belt ratio is more than 5%, preferably more than 10%, preferably more than 15%, preferably more than 20%, preferably more than 25%, and more preferably more than 30%. B. The crystallinity decreases by more than 5%, preferably more than 10%, more than 15%, more than 20%, more than 25%, and more than 30% as characterized by X-ray diffraction patterns, with the degree of crystallinity change in the amorphous region being greater than that in the crystalline region; C. The microstructure undergoes the following changes: the indentation on the particle surface expands, creating depressions, forming pores, surface pitting, fractures and cracks, and / or mechanical damage to the particle surface. D. The expansion force is increased by 10% or more, preferably 20% or more, preferably 30% or more, preferably 40% or more, preferably 50% or more, more preferably 60% or more; and / or E. The gelatinization temperature is reduced by more than 5%, preferably more than 10%, more preferably more than 15%, more preferably more than 20%, more preferably more than 25%, and more preferably more than 30%. In the expansion force experiment, the formula for calculating the expansion force is: Expansion force (g / g) = Weight of residual sediment ÷ (Weight of dry starch - Weight of dissolved starch).

6. The method as described in claim 1, characterized in that, The micro / nano bubble technology includes the following steps: (1) Disperse starch in water at a ratio of 5-35% w / w, preferably 10-30% w / w, preferably 10-25% w / w, preferably 15-25% w / w to form a starch dispersion; (2) Using a micro-nano bubble forming device, gaseous micro-nano bubbles with a diameter of 10nm-100μm, preferably 20nm-80μm, preferably 30nm-70μm, more preferably 40nm-60μm, more preferably 50nm-50μm are introduced into the starch dispersion, and the micro-nano bubbles are retained in the starch dispersion for a time that effectively changes the starch molecular structure until the predetermined physicochemical index is reached, to obtain a hydrodynamic cavitation treatment liquid; (3) Centrifuge the hydrodynamic cavitation treatment fluid, discard the supernatant, and obtain modified starch sediment; or The hydrodynamic cavitation treatment fluid was directly spray-dried to obtain hydrodynamic cavitation-assisted microbubble modified starch, i.e., modified starch. (4) The modified starch sediment in step (3) is dried to obtain hydrodynamic cavitation-assisted microbubble modified starch, i.e., modified starch.

7. The method as described in claim 6, characterized in that, The micro-nano bubble forming device mentioned in step (2) is a fluid dynamics cavitation device, namely a micro-nano bubble generator.

8. The method as described in claim 6, characterized in that, In step (2), the formed micro-nano bubbles are introduced into the starch dispersion at a speed of about 8000 rpm or more, preferably 9000 rpm or more, preferably 10000 rpm or more, and more preferably 11000 rpm using a homogenizer.

9. A modified starch, characterized in that, It is prepared by the method described in any one of claims 1-8.

10. The modified starch according to claim 9, characterized in that, Used in food manufacturing and adhesive manufacturing.

Images