Processing method for delaying starch retrogradation and application

Abstract

The invention discloses a processing method for delaying starch retrogradation and application. The invention belongs to the technical field of food processing. The invention aims to solve the technical problems of food safety, non-environmental protection and high cost of the existing method for delaying starch retrogradation. The method comprises the following steps: uniformly mixing starch, maltitol and fatty acid in proportion to obtain mixed powder, and then extruding, drying and crushing the mixed powder through a double-screw extruder. The maltitol-palmitic acid-corn starch is subjected to extrusion treatment, so that amylopectin is degraded, and recrystallization of amylose is inhibited. In the extrusion process, close combination of starch molecules and maltitol is promoted, interaction between amylose molecules is hindered, and retrogradation of corn starch is inhibited. Meanwhile, palmitic acid and amylose interact to form a stable amylose-lipid compound, winding and stacking of amylose double helixes are hindered, and starch retrogradation is effectively delayed.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a processing method for delaying starch retrogradation and application. Background Art

[0002] As the main source of carbohydrates, starch plays a vital role in human diet and is also an indispensable raw material in food industry production. Natural starch contains a large number of hydroxyl groups, which can form a large number of hydrogen bonds within and between natural starch molecules, resulting in poor water retention and easy retrogradation of natural starch. During storage, starchy foods are prone to increase in hardness and decrease in viscoelasticity, which deteriorates their quality and shortens their shelf life, severely limiting the application of starch in the food industry.

[0003] The gelatinization of starch refers to the process in which starch granules absorb water and swell to form a paste-like solution after being heated. In this process, the structure of starch granules is destroyed, changing from an ordered crystalline state to a disordered state. After cooling, the destroyed starch molecular chains tend to be parallel again, and the amylose and amylopectin recombine into an ordered structure. This process is called starch retrogradation. Starch retrogradation is divided into short-term retrogradation and long-term retrogradation. Short-term retrogradation is due to the rapid gelation of amylose, which re-establishes the three-dimensional network structure between molecules, causing the starch to undergo irreversible crystallization. Long-term retrogradation is that the high branching structure of amylopectin is easily inhibited during the recrystallization process, so the recrystallization rate is slow, and its external chain length and distribution will also affect the crystallization rate.

[0004] At present, the methods for delaying starch retrogradation mainly include physical method, chemical method and bio-enzyme method. However, chemical method is unacceptable to consumers due to its safety issues, and it will produce a lot of wastewater and pollute the environment. Bio-enzyme method also has problems such as high cost and small processing volume. Therefore, it is very important to find an efficient and safe physical method to delay starch retrogradation. Summary of the invention

[0005] The purpose of the present invention is to solve the food safety problem, environmental pollution and high cost of the current method for delaying starch retrogradation, and to provide a processing method and application for delaying starch retrogradation.

[0006] The technical solution of the present invention is as follows:

[0007] One of the objects of the present invention is to provide a processing method for delaying starch retrogradation, which is carried out according to the following steps:

[0008] Starch, maltitol and fatty acid are mixed in proportion to obtain mixed powder, which is then extruded, dried and crushed by a twin-screw extruder.

[0009] Further defined, starch includes corn starch, bean starch, sweet potato starch, potato starch, wheat starch and rice starch.

[0010] Further defined, fatty acids include palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid.

[0011] It is further defined that the maltitol content in the mixed powder is 1-10wt%, and the fatty acid content is 0.1-1wt%.

[0012] It is further defined that the maltitol content in the mixed powder is 5wt% and the fatty acid content is 0.5wt%.

[0013] It is further defined that the temperature zone settings of the twin-screw extruder are: zone one temperature 30-80°C, zone two temperature 50-100°C, zone three temperature 80-130°C, zone four temperature 80-130°C, zone five temperature 90-150°C, zone six temperature 90-150°C, zone seven temperature 100-180°C, zone eight temperature 100-180°C.

[0014] It is further defined that the screw speed is 100-200 rpm, the feed rate is 30-50 rpm, and the moisture content is 30-50%.

[0015] It is further defined that the drying temperature is 30-50°C and the drying time is 10-20h.

[0016] The second object of the present invention is to provide a resistant starch prepared by the above method.

[0017] The third object of the present invention is to provide an application of the resistant-retrogradation starch prepared by the above method in the food field.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention uses starch as a substrate and adopts a twin-screw extrusion device to extrude maltitol-palmitic acid-corn starch. Extrusion causes the degradation of amylopectin and inhibits the recrystallization of amylose. During the extrusion process, the close combination of starch molecules and maltitol is promoted, the interaction between amylose molecules is hindered, and the retrogradation of corn starch is inhibited. At the same time, palmitic acid interacts with amylose to form a stable amylose-lipid complex, which hinders the entanglement and accumulation of amylose double helix and effectively delays starch retrogradation. The present invention utilizes extrusion treatment and maltitol and palmitic acid synergistic treatment to regulate starch retrogradation, improve the anti-retrogradation ability of starch, and extend the shelf life of starch foods. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a comparison chart of the retrogradation values ​​of the starches obtained in Example 1-3 and Comparative Example 1-3 after gelatinization;

[0021] Figure 2 This is a comparison chart of the retrogradation enthalpy values ​​of the starch obtained in Example 1-3 and Comparative Example 1-3 after storage for 7 days and 14 days;

[0022] Figure 3 The following are comparison graphs of the starch X-ray diffraction patterns obtained in Examples 1-3 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0025] The terms "comprising," "including," "having," "containing," or any other variations thereof, as used in the following examples, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus comprising the listed elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0026] Embodiment 1:

[0027] The corn starch is mixed with maltitol and palmitic acid to form a maltitol-palmitic acid-corn starch mixed powder, wherein the amount of maltitol added is 5wt% and the amount of palmitic acid added is 0.5wt%; after mixing, the materials are homogenized and balanced for 12 hours; the maltitol-palmitic acid-corn starch mixed powder is extruded in a twin-screw extruder, and the mixed powder is modified by the multi-stage variable temperature and shear pressure of the extruder, and the extruded material is stably output by adjusting the material speed and moisture content, wherein the temperature zone of the twin-screw extruder is set to: the temperature of the first zone is 40°C, the temperature of the second zone is 40°C, and the temperature of the second zone is 40°C. The temperature of the first zone is 60℃, the temperature of the third zone is 80℃, the temperature of the fourth zone is 90℃, the temperature of the fifth zone is 110℃, the temperature of the sixth zone is 110℃, the temperature of the seventh zone is 120℃, the temperature of the eighth zone is 120℃, the screw speed is 150r / min, the feeding speed is 40r / min, the moisture content is 30%, and the twin-screw extrudate of corn starch is obtained; the obtained twin-screw extrudate of corn starch is cooled to room temperature, dried in a hot air drying oven, the drying temperature is 40℃, and the drying time is 12h; the dried extrudate is crushed and sieved with a mesh number of 100; finally, the anti-retrogradation starch is obtained. This method significantly inhibits the retrogradation of corn starch and can be applied to corn staple food products.

[0028] Embodiment 2:

[0029] The corn starch is mixed with maltitol and palmitic acid to form a maltitol-palmitic acid-corn starch mixed powder, wherein the amount of maltitol added is 1wt% and the amount of palmitic acid added is 0.5wt%; after mixing, the materials are homogenized and balanced for 12 hours; the maltitol-palmitic acid-corn starch mixed powder is extruded in a twin-screw extruder, and the mixed powder is modified by the multi-stage variable temperature and shear pressure of the extruder, and the extruded material is stably output by adjusting the material speed and moisture content, wherein the temperature zone of the twin-screw extruder is set to: the temperature of the first zone is 40°C, the temperature of the second zone is 40°C, and the temperature of the second zone is 40°C. The temperature of the first zone is 60℃, the temperature of the third zone is 80℃, the temperature of the fourth zone is 80℃, the temperature of the fifth zone is 90℃, the temperature of the sixth zone is 100℃, the temperature of the seventh zone is 110℃, the temperature of the eighth zone is 120℃, the screw speed is 160r / min, the feeding speed is 45r / min, the moisture content is 35%, and the twin-screw extrudate of corn starch is obtained; the obtained twin-screw extrudate of corn starch is cooled to room temperature, dried in a hot air drying oven, the drying temperature is 40℃, and the drying time is 12h; the dried extrudate is crushed and sieved with a mesh number of 100; finally, the anti-retrogradation starch is obtained. This method significantly inhibits the retrogradation of corn starch and can be applied to corn staple food products.

[0030] Embodiment 3:

[0031] The corn starch is mixed with maltitol and palmitic acid to form a maltitol-palmitic acid-corn starch mixed powder, wherein the amount of maltitol added is 10wt% and the amount of palmitic acid added is 0.5wt%; after mixing, the materials are homogenized and balanced for 12 hours; the maltitol-palmitic acid-corn starch mixed powder is extruded in a twin-screw extruder, and the mixed powder is modified by the multi-stage variable temperature and shear pressure of the extruder, and the extruded material is stably output by adjusting the material speed and moisture content, wherein the temperature zone of the twin-screw extruder is set to: the temperature of the first zone is 40°C, the temperature of the second zone is 40°C, and the temperature of the second zone is 40°C. The temperature of the first zone is 60℃, the temperature of the third zone is 90℃, the temperature of the fourth zone is 90℃, the temperature of the fifth zone is 100℃, the temperature of the sixth zone is 110℃, the temperature of the seventh zone is 110℃, the temperature of the eighth zone is 120℃, the screw speed is 140r / min, the feeding speed is 30r / min, the moisture content is 25%, and the twin-screw extrudate of corn starch is obtained; the obtained twin-screw extrudate of corn starch is cooled to room temperature, dried in a hot air drying oven, the drying temperature is 40℃, and the drying time is 12h; the dried extrudate is crushed and sieved with a mesh number of 100; finally, the anti-retrogradation starch is obtained. This method significantly inhibits the retrogradation of corn starch and can be applied to corn staple food products.

[0032] Comparison sample 1:

[0033] A twin-screw extruder is used to process corn starch, and the corn starch is modified by multi-stage variable temperature and shear pressure of the extruder. The extruded material is stably output by adjusting the material speed and moisture content, wherein the temperature zones of the twin-screw extruder are set as follows: zone 1 temperature 40°C, zone 2 temperature 60°C, zone 3 temperature 80°C, zone 4 temperature 90°C, zone 5 temperature 110°C, zone 6 temperature 120°C, zone 7 temperature 120°C, zone 8 temperature 120°C, screw speed 160r / min, feed speed 40r / min, moisture content 30%, and twin-screw extrudate of corn starch is obtained; the obtained corn starch twin-screw extrudate is cooled to room temperature, and dried in a hot air drying oven at a drying temperature of 40°C and a drying time of 12h; the dried extrudate is crushed and sieved with a mesh number of 100 meshes; and finally, anti-retrogradation starch is obtained.

[0034] Comparison sample 2:

[0035] The corn starch and maltitol are uniformly mixed to form a maltitol-corn starch mixed powder, wherein the amount of maltitol added is 1wt%; after mixing, the materials are homogenized and balanced for 12h; the maltitol-corn starch mixed powder is extruded in a twin-screw extruder, and the mixed powder is modified by the multi-stage variable temperature and shear pressure of the extruder, and the extruded material is stably output by adjusting the material speed and moisture content, wherein the temperature zones of the twin-screw extruder are set as follows: the temperature of zone 1 is 40°C, the temperature of zone 2 is 60°C, and the temperature of zone 3 is 80°C. ℃, zone four temperature is 90℃, zone five temperature is 100℃, zone six temperature is 110℃, zone seven temperature is 110℃, zone eight temperature is 120℃, screw speed is 165r / min, feeding speed is 40r / min, moisture content is 35%, and corn starch twin-screw extrudate is obtained; the obtained corn starch twin-screw extrudate is cooled to room temperature, dried in a hot air drying oven, the drying temperature is 40℃, and the drying time is 12h; the dried extrudate is crushed and sieved with a mesh number of 100 mesh; finally, the anti-retrogradation starch is obtained.

[0036] Comparison sample 3:

[0037] Corn starch and palmitic acid are mixed evenly to form a palmitic acid-corn starch mixed powder, wherein the amount of palmitic acid added is 0.5wt%; after mixing, the materials are homogenized and balanced for 12 hours; the palmitic acid-corn starch mixed powder is extruded in a twin-screw extruder, and the mixed powder is modified by the multi-stage variable temperature and shear pressure of the extruder, and the extruded material is stably output by adjusting the material speed and moisture content, wherein the temperature zones of the twin-screw extruder are set to: zone 1 temperature 45°C, zone 2 temperature 60°C, zone 3 temperature 80°C , the temperature of zone 4 is 90°C, the temperature of zone 5 is 90°C, the temperature of zone 6 is 100°C, the temperature of zone 7 is 110°C, the temperature of zone 8 is 120°C, the screw speed is 160r / min, the feeding speed is 40r / min, the moisture content is 30%, and a twin-screw extrudate of corn starch is obtained; the obtained twin-screw extrudate of corn starch is cooled to room temperature, and dried in a hot air drying oven at a drying temperature of 40°C and a drying time of 12h; the dried extrudate is crushed and sieved with a mesh number of 100 mesh; finally, the anti-retrogradation starch is obtained.

[0038] (I) Regeneration value test: Accurately weigh 3g of sample and put it into the RVA (Rapid Viscosity Analyzer) special aluminum box, add 25mL of distilled water, and measure it in the Rapid Viscosity Analyzer according to the method specified by the American Cereal Chemistry Association. The procedure is as follows: keep at 50℃ for 1min, increase the temperature to 95℃ within 3.75min at 12℃ / min, keep at 95℃ for 2.5min, then reduce to 50℃ within 3.75min, and continue to keep warm for 2min. The stirring rate is 960r / min in the first 10s, and then the stirring rate is 160r / min for measurement.

[0039] The results are as follows Figure 1 As shown by Figure 1 It can be seen that the maltitol-palmitic acid-corn starch used in the present invention has a retrogradation value of 143cP, 196cP and 197cP after extrusion treatment, which is significantly lower than that of comparative samples 1-3, indicating that the samples prepared by this method have good anti-retrogradation ability and can significantly delay the short-term retrogradation of starch. When maltitol and palmitic acid are not added (comparative sample 1), the retrogradation value is significantly increased compared with Examples 1-3. When only maltitol is added to the system, its retrogradation value is reduced compared with comparative sample 1, indicating that maltitol hinders the interaction between straight-chain starch molecules and inhibits the retrogradation of corn starch. When only palmitic acid is added to the system, its retrogradation value is significantly reduced compared with comparative sample 1, indicating that palmitic acid forms a starch-lipid complex with starch and inhibits starch retrogradation. Examples 1-3 have lower retrogradation values. Compared with comparative samples 2 and 3, the retrogradation value of Example 1 is reduced by 80.38% and 56.27%. It shows that during the extrusion process, the synergistic effect of maltitol and palmitic acid can better regulate the short-term retrogradation of starch.

[0040] (ii) Retrogradation enthalpy test: The gelatinized samples were cooled to room temperature, stored in a refrigerator at 4°C for 7 and 14 days, and then freeze-dried and sieved to determine the retrogradation enthalpy. The determination method is as follows: Accurately weigh (3.0±0.02) mg of sample, mix with distilled water at a mass ratio of 1:3, seal and cover, place at 4°C for equilibration for 24 hours, and measure the enthalpy change using a differential scanning calorimeter, with an empty crucible as a reference. In a nitrogen atmosphere (flow rate of 40 mL / min), heat from 20°C to 100°C at a rate of 10°C / min. Calculate the enthalpy value from the DSC curve using Nstzsch analysis software. (The larger the retrogradation enthalpy value, the higher the degree of retrogradation of the sample and the weaker the anti-regradation ability).

[0041] The results are as follows Figure 2 As shown by Figure 2 It can be seen that the ΔHr of the maltitol-palmitic acid-corn starch used in the present invention after extrusion treatment 7 0.798 J / g, 1.579 J / g and 1.261 J / g, ΔHr 14 The results are as follows: 1.016 J / g, 1.901 J / g and 1.514 J / g, which are significantly lower than those of Comparative Samples 1-3, indicating that the present method can significantly delay the long-term retrogradation of starch. 7 3.206 J / g, ΔHr 14 The regeneration enthalpy of Example 1 was reduced by 75.11% and 81.24% compared with that of Example 1. When only maltitol was added to the system (Comparative Sample 2), its ΔHr 7 2.468 J / g, ΔHr 14 is 4.021 J / g. Compared with comparative sample 1, its enthalpy of retrogradation is reduced by 23.02% and 25.74%, indicating that maltitol wraps the starch molecular chain through non-covalent bonds such as hydrogen bonds, interferes with the rearrangement of starch molecules and inhibits the long-term retrogradation of corn starch. When only palmitic acid is added to the system (comparative sample 3), its ΔHr 7 1.774 J / g, ΔHr 14 The retrogradation enthalpy of Examples 1-3 was significantly reduced compared with Comparative Samples 2 and 3 at 7 and 14 days of retrogradation, indicating that the synergistic effect of maltitol and palmitic acid can better regulate the long-term retrogradation of starch during extrusion.

[0042] (III) X-ray diffraction: The RVA gelatinized sample was freeze-dried and then crushed. The treated sample was scanned with CuK-α radiation at 40KV and 40MA, with a range of 5-40°, a scanning rate of 2° / min, and a scanning step of 0.02°.

[0043] X-ray diffraction curves such as Figure 3 As shown, different crystal structures have different diffraction characteristic peaks. The samples of maltitol-palmitic acid-corn starch used in the present invention after extrusion treatment have obvious diffraction peaks at 8°, 13°, 17° and 20°, showing a typical B+V type. Comparative sample 1 and comparative sample 2 both have diffraction peaks at 17° and 20°, indicating that the addition of maltitol during the extrusion process will not affect the crystal form of starch. Comparative sample 3 has diffraction peaks at 13° and 20°, while the diffraction peak at 17° disappears. At this time, the crystal type of starch is a V-type crystal structure. The change in relative crystallinity (RC) can reflect the orderly arrangement of starch chains and is an important indicator for measuring the degree of starch retrogradation. The relative crystallinity of comparative sample 2 is lower than that of comparative sample 1, which may be because maltitol wraps the starch molecular chain through non-covalent bonds such as hydrogen bonds, interfering with the rearrangement of starch molecules. The relative crystallinity of comparative sample 3 is also lower than that of comparative sample 1. This result is attributed to the formation of a V-type complex between amylose and palmitic acid, which reduces the recrystallization between amylose molecules. Compared with the control sample, the relative crystallinity of the three groups of examples is lower, indicating that palmitic acid and maltitol have a synergistic effect on inhibiting starch recrystallization during the extrusion process.

[0044] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for delaying starch retrogradation, characterized in that: The method: Starch, maltitol and fatty acid are mixed in proportion to obtain mixed powder, which is then extruded, dried and crushed by a twin-screw extruder.

2. The method according to claim 1, characterized in that Starches include corn starch, bean starch, sweet potato starch, potato starch, wheat starch and rice starch.

3. The method according to claim 1, characterized in that Fatty acids include palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid.

4. The method according to claim 1, characterized in that: The content of maltitol in the mixed powder is 1-10wt%, and the content of fatty acid is 0.1-1wt%.

5. The method according to claim 4, characterized in that The content of maltitol in the mixed powder is 5wt%, and the content of fatty acid is 0.5wt%.

6. The method according to claim 1, characterized in that Twin-screw extruder temperature zone settings: zone 1 temperature 30-80℃, zone 2 temperature 50-100℃, zone 3 temperature 80-130℃, zone 4 temperature 80-130℃, zone 5 temperature 90-150℃, zone 6 temperature 90-150℃, zone 7 temperature 100-180℃, zone 8 temperature 100-180℃.

7. The method according to claim 1, characterized in that The screw speed is 100-200rpm, the feed rate is 30-50rpm, and the moisture content is 30-50%.

8. The method according to claim 1, characterized in that The drying temperature is 30-50℃ and the drying time is 10-20h.

9. Retrogradation-resistant starch obtained by the method according to any one of claims 1 to 8.

10. Use of the resistant-retrogradation starch according to claim 9 in the food field.

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