A method for preparing V-type cold water soluble starch at normal pressure rapidly

Abstract

The present application belongs to the technical field of starch modification innovation, and specifically relates to a green and effective method and experimental mode for preparing V-type starch capable of being quickly formed under normal pressure by using glycerol as a dispersing system and gelatinized corn starch, which can be used in the production of various edible products such as fruit juice and rice noodles. Starch is considered to be the main carbohydrate reserve material of higher plants, and has many excellent physicochemical properties, such as biodegradability, non-toxicity and low production cost. It mainly consists of two main biopolymers: amylose (20-30%) and highly branched amylopectin (70-80%). The linear amylose of starch is induced to form a single helix structure accumulation in V-type crystals, and the inclusion compound can be used to encapsulate small hydrophobic guests. V-type granular starch, as a modified starch, retains the granular form of natural starch, but increases its cold water solubility. The low-cost V-type granular starch has many applications in the fields of food, medicine and chemical industry. The present application provides V-type cold water soluble starch prepared quickly by glycerol, the number of V-type crystals is large, the encapsulation capacity is stronger, the solubility in cold water can improve the viscosity, and the thickening effect can be achieved in food, and the starch is also a very good encapsulation material.

Description

Technical Field

[0001] This invention belongs to the field of starch modification technology, specifically involving the use of glycerol as a dispersion system to gelatinize corn starch. It describes a green and effective method for preparing V-shaped starch by gelatinization under normal pressure, which can be used in the production of various edible products such as fruit juice and rice noodles to improve their properties. Background Technology

[0002] Starch is considered the primary carbohydrate reserve material in higher plants, mainly composed of two major biopolymers: amylose (20-30%) and highly branched amylopectin (70-80%). Starch possesses many excellent physicochemical properties, such as biodegradability, non-toxicity, and low production cost. Modified starch has developed rapidly in my country, employing methods including physical modification, chemical modification, and enzymatic modification. Among these, physical modification poses no threat to human health, avoids the environmental pollution problems associated with chemical reagents, and is simple and rapid to perform, thus attracting increasing attention from researchers.

[0003] V-shaped granular starch, as a modified starch, retains the granular form of natural starch. The linear amylose in starch is induced to form a single-helix structure stacked in V-shaped crystals, forming inclusion complexes that can be used to encapsulate small hydrophobic guests. Low-cost V-shaped granular starch has many applications in the food, pharmaceutical, and chemical industries. V-shaped starch is typically prepared by heating starch in an ethanol-water solution in a sealed high-pressure reactor. In the two steps of water-ethanol heat treatment to form V-shaped starch, the temperature affects the heating of the native starch in the ethanol-water solution under high pressure. Furthermore, when using ethanol precipitation to gelatinize starch to prepare V-shaped starch carriers, the precipitation process is usually carried out at room temperature, requiring an additional annealing process, which not only affects the recovery rate of the V-shaped starch carrier but also leads to increased consumption of reagents, time, and energy, increasing the cost of the method. Therefore, it is crucial to develop V-shaped starch carriers with excellent loading performance through a convenient and green method. This study proposes research on preparing V-shaped starch carriers with excellent V-shaped crystal structures using a high-volume, green, mild solvent under ambient pressure.

[0004] Glycerin is a green, mild, and commonly used plasticizer with good biocompatibility. Studies have found that glycerol regulates molecular fluidity and hydrogen bond networks in amorphous glass matrices of starch, potentially interfering with V-type starch formation by influencing the stacking of amylose chains. Annealing at 140°C allows glycerol to complex with linear amylose to form an ordered V-shaped structure. This method requires no additional annealing, exhibits high cold water solubility, and is a simple and efficient method for preparing V-type starch.

[0005] Cold water solubility is a crucial property of V-type starch. V-type starch dissolves directly in cold water to form a highly dispersed, homogeneous paste with rapid dissolution, stable state, transparent texture, and high viscosity. It exhibits excellent thickening, water retention, shape retention, emulsifying properties, and good high-temperature resistance and freeze-thaw stability, making it widely used in the food industry. It is suitable for various convenience foods, eliminating the need for cooking and serving as a thickener and improving texture. The rapid hydration of granular cold water-soluble starch, producing the functional properties of cookable starch without heating, is also widely applied in the food industry. Therefore, this invention provides a green and rapid method for preparing V-type starch under normal pressure, reducing the processing cost of heat-modified starch, and is environmentally friendly, possessing considerable market acceptance. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing cold-water soluble V-type starch, which alters the microstructure, gelatinization properties, and crystal structure, thereby improving the cold-water solubility of V-type starch. V-type starch is prepared by atmospheric pressure treatment under glycerol conditions at 140℃. The starch granules gradually break down from the center outwards, exhibiting a ring-like shape, which disrupts the double-helix structure of the starch and rapidly generates viscosity. Simultaneously, during this process, the A-type crystallinity of the starch decreases, while the V-type crystallinity increases, and the short-range ordered structure increases. The V-type starch prepared by this method exhibits a significantly increased V-type crystallinity to 37.64%, resulting in a 436.6% improvement in encapsulation capacity. Figure 1 As shown in the figure, this invention establishes a green and efficient method for preparing V-type starch, and the starch produced has excellent encapsulation capabilities, which is expected to accelerate the commercial application of V-type starch, reduce production costs in the food, chemical, and pharmaceutical industries, and promote industry progress.

[0007] This invention provides a V-type cold water-soluble starch that can be rapidly prepared from glycerol. Figure 2 The results showed that, compared to natural corn starch, natural corn starch exhibited irregular elliptical or circular cracks, and the fluorescence intensity around the hilum of the starch granules was higher. In contrast, V-shaped starch prepared by glycerol treatment at 140℃ showed a brighter fluorescent ring, while the strong fluorescence inside the granules disappeared, indicating that this area was destroyed from the outset, making the central region of the granule the most porous. Furthermore, under a polarizing microscope, natural corn starch granules displayed a typical Maltese cross, and under the same background, the birefringence of smaller granules appeared slightly weaker than that of larger granules. However, the V-shaped starch prepared by atmospheric pressure treatment at 140℃ showed that the corn starch granules were broken into small fragments, and both their surface and internal structures were effectively destroyed, with the Maltese cross disappearing. These findings indicate that the destruction of V-shaped starch prepared by this method begins from the center of the granules, resulting in a loose structure in the central region. Figure 2 As shown.

[0008] This invention provides a V-shaped cold water-soluble starch rapidly prepared from glycerol. Unlike the uneven shape of natural corn starch granules (including spherical, irregular, and polygonal granules with smooth surfaces), the V-shaped starch treated at 140°C under normal pressure exhibits a donut-like shape, indicating significant damage to the corn starch granules. Based on this phenomenon, the larger granules show lower gelatinization resistance, possibly because they have a lower amylose content, resulting in a weaker structure and easier hydrolysis. The destruction of the starch structure begins at the center and rapidly expands to the periphery. The change in granule morphology indicates that glycerol treatment triggers a significant swelling or gelatinization process, accompanied by a series of changes such as the dissociation of the amylopectin double helix and the leaching of amylose components. At this point, the starch granules are essentially destroyed. Figure 2 and Figure 3 The images all showed no discernible particles, indicating that glycerol, as a medium for unwinding the amylose single helix and amylopectin double helix, can improve the cold water solubility of starch.

[0009] This invention provides a V-type cold water-soluble starch rapidly prepared from glycerol. Unlike natural corn starch, which exhibits a single endothermic peak, this starch gelatinizes from 58.3°C (T0) to 65.7°C (Tp), completing the gelatinization process at 68.7°C. The V-type starch obtained by this method does not have a single endothermic peak, and the temperature of 140°C promotes the dissociation of the amylopectin double helix and the transition from unwinding to coiling. Figure 4 As shown.

[0010] This invention provides a V-type cold water-soluble starch rapidly prepared from glycerol, which has a completely different crystal structure from the A-type of natural corn starch. At 140°C, the main peaks (15.1°, 17.2°, 23.2°) of the A-type starch become relatively flat, indicating that most of the well-structured A-type crystals have been destroyed. Furthermore, the main peaks (7.8°, 13.8°, 20.8°) of the V-type starch change from gentle to sharp, with a significant increase in V-type crystallinity to 37.64%. The fluidity of the amylose chains increases, and some amorphous structures are transformed into single helices under the induction of glycerol molecules, indicating V-type starch crystallization, a more perfect starch crystal form, and stronger encapsulation capabilities. Figure 5 As shown. Attached Figure Description

[0011] Figure 1 This is the iodine absorption curve. NCS represents the original corn starch, and CS-140℃ represents the corn starch sample treated at 140℃.

[0012] Figure 2A1, A2, and A3 are the original corn starch samples observed under a laser confocal microscope, a conventional optical microscope, and a polarized light microscope, respectively; B1, B2, and B3 are the corn starch samples after treatment at 140℃, observed under a laser confocal microscope, a conventional optical microscope, and a polarized light microscope, respectively.

[0013] Figure 3 A1 and A2 are the results of observation of raw corn starch under a scanning electron microscope at 1000 and 3000x magnification, respectively; B1 and B2 are the results of observation of corn starch after treatment at 140℃ under a scanning electron microscope at 1000 and 3000x magnification, respectively.

[0014] Figure 4 This is a DSC curve. NCS represents the original corn starch, and CS-140℃ represents the corn starch sample treated at 140℃.

[0015] Figure 5 These are XRD curves. NCS represents the original corn starch, CS-140℃ represents the corn starch sample treated at 140℃, and W-CS-140℃ represents the corn starch sample treated at 140℃ dissolved in cold water.

[0016] Figure 6 This is a schematic diagram of the sample after being dissolved in water. NCS represents the original corn starch, and CS-140℃ represents the corn starch sample treated at 140℃.

[0017] Figure 7 This is a schematic diagram of a rice noodle sample made by adding corn starch treated at 140℃.

[0018] Figure 8 This is a schematic diagram of a sample made by adding corn starch treated at 140℃ to fruit juice.

[0019] Figure 9 This is a schematic diagram of a corn starch sample treated at 140℃ encapsulating curcumin. Detailed Implementation

[0020] The technical solution of the present invention will now be described in detail through specific embodiments.

[0021] Example 1: Corn starch was dispersed in glycerol to prepare a 6% starch suspension (w / w). The suspension was stirred until homogeneous and then placed in an oil bath at 140°C for gelatinization at 800 rpm for 30 min. After gelatinization, the suspension was cooled to 90°C, and four volumes of 60% ethanol aqueous solution were added. The suspension was then treated at 90°C for 60 min, cooled to 25°C, and centrifuged at 3000 rpm for 5 min to remove the supernatant. Anhydrous ethanol was then added again, and the supernatant was removed by centrifugation. This step was repeated three times. Finally, the precipitate was dried at 40°C to obtain the final product. The prepared starch is V-type starch, which dissolves rapidly in water and exhibits cold water solubility. Figure 6 As shown.

[0022] Example 2: Corn starch was dispersed in glycerol to prepare a 6% starch suspension (w / w). The suspension was stirred until homogeneous and placed in an oil bath at 140°C for gelatinization at 800 rpm for 30 minutes. After gelatinization, the suspension was cooled to 90°C, and four times its volume of 60% ethanol aqueous solution was added. The suspension was treated at 90°C for 60 minutes, cooled to 25°C, and centrifuged at 3000 rpm for 5 minutes to remove the supernatant. Anhydrous ethanol was then added again, and the supernatant was removed by centrifugation. This step was repeated three times. Finally, the precipitate was dried at 40°C to obtain the finished product. The prepared starch was mixed with rice starch in a 1:10 ratio, water was added to form a slurry, and the mixture was stirred until a homogeneous slurry was formed. This slurry was then placed in a screw extruder and extruded at high temperature to produce rice noodles. The resulting rice noodles have a rapidly digestible starch content, improved digestibility, and a chewy, smooth texture. Figure 7 As shown.

[0023] Example 3: Corn starch was dispersed in glycerol to prepare a 6% starch suspension (w / w). The suspension was stirred until homogeneous and placed in an oil bath at 140°C for gelatinization at 800 rpm for 30 min. After gelatinization, the suspension was cooled to 90°C, and four times its volume of 60% ethanol aqueous solution was added. The suspension was treated at 90°C for 60 min, cooled to 25°C, and centrifuged at 3000 rpm for 5 min to remove the supernatant. Then, anhydrous ethanol was added again, and the supernatant was removed by centrifugation. This step was repeated three times. Finally, the precipitate was dried at 40°C to obtain the final product. Diluting the fruit juice pulp at a 1:4 ratio and adding 5% of the prepared V-type starch, followed by shaking, can increase the viscosity of the fruit juice. Figure 8 As shown.

[0024] Example 4: Corn starch was dispersed in glycerol to prepare a 6% starch suspension (w / w). The suspension was stirred until homogeneous and placed in an oil bath at 140°C for gelatinization at 800 rpm for 30 min. After gelatinization, the suspension was cooled to 90°C, and four volumes of 60% ethanol aqueous solution were added. The suspension was treated at 90°C for 60 min, cooled to 25°C, and centrifuged at 3000 rpm for 5 min to remove the supernatant. Anhydrous ethanol was added again, and the supernatant was removed by centrifugation. This step was repeated three times. Finally, the precipitate was dried at 40°C to obtain the final product. Curcumin was added to the prepared starch at a dosage of 1%-10%, and a certain volume of ethanol solution was added. The mixture was stirred until completely dissolved to prepare a starch slurry of a certain concentration. After centrifugation, drying, grinding, and sieving, the starch-curcumin inclusion complex was obtained. Figure 9 As shown.

Claims

1. A cold water-soluble V-type starch rapidly prepared using glycerol, characterized in that, A 6% w / w starch suspension was prepared by stirring corn starch in glycerol and then gelatinized in an oil bath at 140°C for 30 min at 800 rpm. After gelatinization, the suspension was cooled to 90°C, and four volumes of 60% ethanol aqueous solution were added. The suspension was then treated at 90°C for 60 min, cooled to 25°C, and centrifuged at 3000 rpm for 5 min to remove the supernatant. Anhydrous ethanol was added again, and the supernatant was removed by centrifugation. This step was repeated three times. Finally, the precipitate was dried at 40°C to obtain the final product. The starch is rapidly soluble in water and has cold water solubility.

2. The cold water-soluble V-type starch rapidly prepared with glycerol according to claim 1, characterized in that, Under laser confocal microscopy, the fluorescence inside the starch granules disappeared; under polarized light microscopy, the Maltese cross disappeared.

3. The cold water-soluble V-type starch rapidly prepared with glycerol according to claim 2, characterized in that, The starch granules, when observed under a scanning electron microscope, are shaped like donuts.

4. The cold water-soluble V-type starch rapidly prepared with glycerol according to claim 3, characterized in that, The amylopectin double helix of the starch dissociates, and the unwinding helix transforms into a random coiled structure, without any single endothermic peak.

5. The cold water-soluble V-type starch rapidly prepared with glycerol according to claim 4, characterized in that, The amylose chains of the starch exhibit increased mobility, and some amorphous structures are transformed into single-helix crystal structures under the induction of glycerol molecules, changing from type A crystal structure to type V crystal structure, with a V-type crystallinity of 37.64%.

6. The application of the cold water-soluble V-type starch rapidly prepared with glycerol according to any one of claims 1 to 5, characterized in that, The starch is used as a thickener.

7. The application according to claim 6, characterized in that, The starch is used to prepare rice noodles, fruit juice, or starch-curcumin inclusion complexes.

Images