Preparation method of jackfruit seed resistant starch based on ultrasonic treatment

Abstract

The invention belongs to the technical field of starch processing, and particularly relates to a preparation method of jackfruit seed resistant starch based on ultrasonic treatment. Uniformly mixing jack fruit seed starch and plasma activated water to obtain a starch solution; performing ultrasonic treatment on the starch solution, performing gelatinization, then adding gallic acid, performing uniform stirring, performing compounding through a shaking table, performing cooling, performing drying, and performing sieving so as to obtain the jackfruit seed resistant starch. The conditions of the ultrasonic treatment are as follows: the power is 300 to 600 W, the frequency is 40 Hz, and the time is 30 to 60 minutes. The compound with high resistant starch content is prepared by utilizing a synergistic modification method of two physical technologies of ultrasonic wave and plasma activated water. Meanwhile, chemical reagents are not used in the preparation method provided by the invention, and the preparation method can be used in food labeled with clean labels.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of starch processing, and particularly relates to a preparation method of jackfruit seed resistant starch based on ultrasonic treatment. BACKGROUND

[0002] Traditional heating methods mainly form non-inclusion complexes, and microwave processing, extrusion, ultrasonic treatment and other alternative methods can promote the formation of V-type inclusion complexes. Ultrasonic treatment is a technology that has been proven to induce cavitation, which can degrade starch chains by using the cavitation effect of ultrasonic waves, promote the combination of starch and polyphenols, and thus produce resistant starch; on the other hand, it is more conducive to the combination of starch and polyphenols by using the acidic characteristics of plasma-activated water, so the combination of the two may have better digestion resistance and produce more resistant starch content than the use of either alone.

[0003] However, the effects of plasma-activated water and ultrasonic treatment on the preparation and digestibility of starch-polyphenol complexes need to be further studied. Therefore, the present application explores the formation of V-type complexes by ultrasonic treatment of jackfruit seed starch and gallic acid under the condition of plasma-activated water, to provide a new idea for the preparation of starch-polyphenol complexes. SUMMARY

[0004] The present application solves the technical problems of the prior art by providing a preparation method of jackfruit seed resistant starch based on ultrasonic treatment and jackfruit seed resistant starch obtained by the preparation method.

[0005] To solve the above technical problems, the present application discloses a preparation method of jackfruit seed resistant starch based on ultrasonic treatment, which comprises the following steps: mixing jackfruit seed starch and plasma-activated water uniformly to obtain a starch solution; subjecting the starch solution to ultrasonic treatment, then gelatinizing, adding gallic acid, stirring uniformly, compounding by a shaking bed, and sieving after cooling and drying to obtain the jackfruit seed resistant starch.

[0006] The ultrasonic treatment has the following conditions: power 300-600 W, frequency 40 Hz, and time 30-60 min.

[0007] In some embodiments of the present application, the ultrasonic treatment has the following conditions: power 600 W, frequency 40 Hz, and time 30 min.

[0008] The mass-volume ratio of the jackfruit seed starch and the plasma-activated water is 1 g:10 mL.

[0009] The preparation steps of the jackfruit seed starch are as follows: the jackfruit seed is peeled by being soaked in 0.1M NaOH for 5 min, is beaten and sieved, and is left to stand and precipitate overnight. The precipitate is soaked in a 0.5 mol / L Na2S2O3·5H2O solution (1:1) for 36 h, is centrifuged (5000 r / min, 5 min, 20 DEG C) for multiple times, and the supernatant is discharged until there is no brown precipitate on the upper layer of the precipitate. Then, the precipitate is neutralized to neutral by using 1.0 mol / L hydrochloric acid, is washed by using 50% ethanol, is centrifuged (5000 r / min, 5 min, 20 DEG C), and is dried by using a blast drying oven and sieved to obtain the jackfruit seed starch.

[0010] The preparation steps of the plasma-activated water are as follows: 150 mL of distilled water is poured into a beaker, then a plasma-activated water jetting probe is inserted into the beaker to reach below the liquid surface, and the plasma-activated water is obtained by keeping the power at 750 W for 2 min.

[0011] The pasting is performed in a boiling water bath, and the time is 20 min.

[0012] The gallic acid is added in an amount of 10% of the mass of the jackfruit seed starch.

[0013] The compounding is performed at a shaking table oscillation speed of 150 r / min, a temperature of 100 DEG C, and a time of 1.5 h.

[0014] Further, the jackfruit seed resistant starch prepared by the preparation method is also within the protection scope of the present application.

[0015] Specifically, in some embodiments of the present application, the jackfruit seed resistant starch is prepared by the preparation method, and the characterization shows that the resistant starch prepared by the combination of the plasma-activated water and the ultrasonic treatment has increased particle size and increased surface roughness. The crystal type of the compound is changed from C+V type to V type, the relative crystallinity is reduced, the solubility and the swelling degree are significantly improved. The V type compound is successfully prepared by the combination of the plasma-activated water and the ultrasonic treatment and the gallic acid, and the starch digestion rate is significantly reduced.

[0016] Beneficial effects:

[0017] The present application uses the method of the combination of the ultrasonic wave and the plasma-activated water to prepare the compound with high resistant starch content. Meanwhile, no chemical reagent is used in the preparation method provided by the present application, and the compound can be used in the food with a clean label. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and / or other aspects of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the accompanying drawings in which:

[0019] Figure 1 The absorbance value of the complex degree of the resistant starch of jackfruit seeds under the plasma-activated water and ultrasonic treatment in the embodiment of the present application.

[0020] Figure 2 The SEM image of the resistant starch of jackfruit seeds under the plasma-activated water and ultrasonic treatment in the embodiment of the present application.

[0021] Figure 3 The XRD image of the modified starch and the resistant starch of jackfruit seeds under the plasma-activated water and ultrasonic treatment in the embodiment of the present application.

[0022] Figure 4 The FT-IR spectrum of the resistant starch of jackfruit seeds under the plasma-activated water and ultrasonic treatment in the embodiment of the present application.

[0023] Figure 5 The DTG and TGA curve of the resistant starch of jackfruit seeds under the plasma-activated water and ultrasonic treatment in the embodiment of the present application.

[0024] Figure 6 The in vitro digestion curve and the nutritional component content chart of the resistant starch of jackfruit seeds under the plasma-activated water and ultrasonic treatment in the embodiment of the present application. DETAILED DESCRIPTION

[0025] In the following examples, the experimental methods are described, and if no special instructions are given, they are all conventional methods; the reagents and materials, if no special instructions are given, can be obtained from commercial channels.

[0026] In the following examples, the jackfruit seeds (Malaysia No. 1) are purchased from the Internet; the α-amylase (50 U / mg) is purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.; the Aspergillus niger starch glucosidase (100,000 U / g) is purchased from Nanjing Yulei Biological Engineering Co., Ltd.; and the relevant chemical solvents used in the experiment are all of analytical purity.

[0027] Example 1: Preparation of the resistant starch of jackfruit seeds

[0028] Preparation of jackfruit seed starch: Jackfruit seeds were soaked in 0.1M NaOH for 5 min to remove the skin, pulped, sieved, and allowed to stand overnight to precipitate. The precipitate was added to 0.5 mol / L Na2S2O3·5H2O solution (1 g: 1 mL) and soaked for 36 h. The mixture was centrifuged multiple times (5000 r / min, 5 min, 20 ℃), and the supernatant was discarded until no brown precipitate remained on the upper layer. The mixture was then neutralized with 1.0 mol / L hydrochloric acid, washed with 50% ethanol, centrifuged (5000 r / min, 5 min, 20 ℃), and dried in a forced-air drying oven before sieving to obtain jackfruit seed starch.

[0029] Preparation of plasma-activated water: Pour 150 mL of distilled water into a beaker, then insert the plasma-activated water jet probe into the beaker until it is below the liquid surface, and maintain it at a power of 750 W for 2 min to obtain plasma-activated water.

[0030] Preparation of resistant starch from jackfruit seeds: Jackfruit seed starch and plasma-activated water were mixed in a 250 mL Erlenmeyer flask at a mass-to-volume ratio of 1 g:10 mL to prepare a starch solution. The solution was then subjected to ultrasonic treatment at 300 W and 40 Hz for 30 min. Two Erlenmeyer flasks were placed in a boiling water bath for gelatinization for 20 min. Gallic acid (10% of the mass of the jackfruit seed starch) was added to one of the Erlenmeyer flasks, and the mixture was stirred thoroughly. The mixture was then placed in a shaker (150 r / min, 100 ℃) for 1.5 h. After cooling to room temperature, the mixture was freeze-dried and passed through a 100-mesh sieve. The resulting samples of jackfruit seed starch and starch-gallic acid complex, treated with ultrasonic power of 300 W for 30 min, were designated as resistant starch from jackfruit seeds, denoted as P-U300-30 and P-U300-30-G, respectively.

[0031] Keeping other conditions constant, the ultrasound time was adjusted to 60 min to prepare P-U300-60 and P-U300-60-G; the ultrasound power was adjusted to 600W to prepare P-U600-30, P-U600-30-G, P-U600-60 and P-U600-60-G.

[0032] Example 2: Determination of the degree of resistant starch complexation in jackfruit seeds

[0033] To determine whether ultrasonic treatment and plasma-activated water treatment could promote the binding of gallic acid to starch, the content of gallic acid in resistant starch from jackfruit seeds was determined by reducing polyphenolic hydroxyl groups with Folin-Ciocalteu reagent. The specific steps were as follows: Each sample (0.1 g) was added to 5 mL of anhydrous ethanol and incubated in a constant temperature water bath (40℃) for 30 min. After cooling to room temperature, it was centrifuged at 3000 g for 10 min. 1 mL of the supernatant was mixed with 1 mL of Folin-Ciocalteu reagent and reacted in the dark for 5 min, followed by the addition of 1 mL of Na₂CO₃ solution (6%). The mixture was then reacted in a water bath (40 ℃) for 20 min. A starch sample without gallic acid under the same treatment conditions was used as a blank control. The absorbance of the starch-complex sample was measured at 765 nm using a visible-ultraviolet spectrophotometer (Shanghai Yidian Analytical Instrument Co., Ltd., Lambda35).

[0034] Figure 1 The absorbance value of the degree of complexation of resistant starch in jackfruit seeds under plasma-activated water synergistic ultrasonic treatment is determined by... Figure 1 It was observed that the absorbance of the composite sample increased significantly with increasing ultrasonic power, but decreased with prolonged ultrasonic treatment duration. This is mainly because ultrasonic treatment for a certain period causes the starch granules to swell and disintegrate, promoting the interaction between starch and small molecule ligands. However, when the treatment time was further increased, the absorbance of the sample decreased. This is because the outer surface of the starch chain is rich in hydroxyl groups, and gallic acid may bind to the starch chain through hydrogen bonds, hydrophobic interactions, or electrostatic interactions.

[0035] Example 3: Determination of the surface particle structure of resistant starch in jackfruit seeds (SEM)

[0036] The resistant starch sample of jackfruit seeds was evenly coated on a sample stage with conductive tape, and the sample was sputter-coated with gold. The surface morphology of the starch sample particles was observed using SEM (Thermo Fisher Scientific, Verios G4 UC).

[0037] Figure 2 SEM images of resistant starch in jackfruit seeds under plasma-activated water synergistic ultrasonic treatment (A: 5000×, B: 2500×). Figure 2It can be seen that under the combined treatment of plasma-activated water and ultrasound, most jackfruit seed starch granules are round or oval. However, some starch granules show rough small particles on their surface, causing them to aggregate. The destruction of particle integrity becomes more pronounced with increasing ultrasonic power and treatment time. This indicates that the oxidation effect of plasma-activated water treatment causes a certain degree of "erosion" of the starch granules. After adding gallic acid, the surface porosity and roughness of the complex increase, resulting in an uneven structure composed of small, lumpy particles, and the formation of larger aggregates. This phenomenon becomes more pronounced with increased ultrasonic treatment.

[0038] Example 4: Long-range crystal structure analysis (XRD) of resistant starch from jackfruit seeds

[0039] The crystal characteristics of resistant starch samples from jackfruit seeds were determined by XRD (Bruker, D8 Advance) at a scan rate of 4° / min and a 2θ range of 5–35°.

[0040] Figure 3 XRD patterns of modified starch and jackfruit seed resistant starch under plasma-activated water synergistic ultrasonic treatment are shown in Table 1. A represents the XRD pattern of modified starch, and B represents the XRD pattern of jackfruit seed resistant starch. 1022 / 995 R 1047 / 1022 And RC (%) data, where RC (%) is the relative crystallinity; R 1022 / 995 For 1022 and 995 cm -1 The ratio of peak intensity; R 1047 / 1022 1047 and 1022 cm -1 The ratio of peak intensity.

[0041] Table 1. R of resistant starch in jackfruit seeds under plasma-activated water synergistic ultrasonic treatment 1022 / 995 R 1047 / 1022 and RC (%)

[0042]

[0043] Note: Results are expressed as mean ± standard deviation (n=3); different letters in the same column indicate significant differences (p< 0.05).

[0044] Depend on Figure 3As shown in Table 1, the diffraction peaks of jackfruit seed starch and starch-gallic acid complex differed under plasma-activated water and ultrasonic treatment. After synergistic treatment with plasma-activated water and ultrasound, the crystal form of jackfruit seed starch changed from type A to type B, and its crystallinity increased. The complex sample P-U300-30-G exhibited a typical C+V crystal structure, and its crystallinity increased from 22.971% to 39.567%. The synergistic treatment with plasma-activated water and ultrasound disrupted the double helix structure of amylopectin in jackfruit seed starch, leading to the formation of V-type inclusion complexes or non-V-type complexes by non-covalent interactions with phenolic substances. When the ultrasonic treatment time was extended to 60 min, the diffraction peak at 22.60° of the complex sample P-U300-60-G disappeared, the crystal structure transitioned from C+V to V-type, and the crystallinity decreased to 33.043%. When the ultrasonic treatment power reached 600 W, the composite samples P-U600-30-G and P-U600-60-G lost their diffraction peaks at 22.60° and 27.55°, respectively, and their crystalline structure completely transformed into V-type crystals. Their crystallinity was 47.053% and 44.630%, respectively, and their RC increased with increasing ultrasonic treatment power, showing an inverse trend with treatment time.

[0045] Example 5: Short-range crystal structure analysis (FT-IR) of resistant starch from jackfruit seeds

[0046] Jackfruit seed resistant starch samples were mixed with potassium bromide at a ratio of 1 mg:100 mg to form thin films, which were then analyzed using an FT-IR spectrometer (Bruker, T27) in the wavelength range of 4000–400 cm⁻¹. -1 The resolution is 4 cm. -1 Under these conditions, structural analysis was performed on starch samples.

[0047] Figure 4 FT-IR spectra of resistant starch in jackfruit seeds after plasma-activated water synergistic ultrasonic treatment. Figure 4 It can be seen that no new absorption peaks appeared in the FT-IR spectra of all starch samples, indicating that there is a non-covalent interaction between jackfruit seed starch and gallic acid under the action of ultrasound and plasma-activated water.

[0048] Meanwhile, the wavenumber is 4000~3000 cm. -1 The narrowing of the full width at half maximum (WHM) of the band indicates that gallic acid interferes with intramolecular and intermolecular hydrogen bonds in starch. The -OH groups of gallic acid and glucose units may participate in hydrogen bond formation, driving the binding of gallic acid and jackfruit seed starch. On the other hand, at 1047, 1022, and 995 cm⁻¹... −1The absorption peak at [location] reflects the structural characteristics of the crystalline and amorphous regions of starch. Compared with jackfruit seed starch samples under the same treatment conditions, the R [value] in the starch-gallic acid complex sample [values]. 1022 / 995 The value of R decreases. 1047 / 1022 The value of shows an upward trend. In the complex formed by gallic acid and starch, R 1047 / 1022 The value was significantly higher than that of starch without added polyphenols, indicating enhanced orderliness of the crystalline regions.

[0049] Example 6: Analysis of the thermal stability of resistant starch in jackfruit seeds (TGA)

[0050] The thermal properties of resistant starch samples from jackfruit seeds were determined using a thermogravimetric analysis (TGA) instrument (PE, TL9000). 5.0 mg of sample was weighed and heated from 30 °C to 600 °C at a rate of 10 °C / min while maintaining a nitrogen flow rate of 20 mL / min. The thermogravimetric analysis curve (TGA curve) and differential thermogravimetric curve (DTG curve) were then obtained.

[0051] Figure 5 The image shows the DTG and TGA curves of resistant starch in jackfruit seeds under plasma-activated water synergistic ultrasonic treatment, where A represents DTG and B represents TGA. Figure 5 It was found that two distinct mass loss zones existed in all samples. The first stage of mass loss occurred around 120 °C, which is related to the evaporation of adsorbable moisture in the samples. The second weight loss occurred between 220 °C and 330 °C, mainly attributed to the breakage of starch molecular chains during heating. The TGA curves of the starch samples showed that the thermal degradation temperature of the starch sample without gallic acid (260 °C) was higher than that of the complex (220 °C), indicating that starch has a more complex and stable structure than phenolic acids. This result clarifies that the introduction of gallic acid reduces the thermal stability of jackfruit seed starch.

[0052] Example 7: Determination of the digestibility of resistant starch in jackfruit seeds

[0053] 25.0 mg of starch sample was mixed with 5 mL of sodium acetate buffer and equilibrated in a 37 °C water bath for 15 min. Then, the starch sample solution was mixed with 2 mL of α-amylase and 0.5 mL of amyloglucosidase and stirred continuously (180 r / min) in a 37 °C water bath. 0.5 mL of the digest was extracted at time intervals of 0, 10, 20, 30, 60, 90, 120, and 180 min. The hydrolysis products at different time intervals were mixed with an equal volume of sodium carbonate to terminate the reaction, and the mixture was then centrifuged at 5000 g for 10 min to obtain the supernatant. The reducing sugar content was determined using the DNS method. 1 mL of a diluted supernatant was thoroughly mixed with 1.5 mL of DNS and boiled for 5 min. The cooled solution was kept at a constant volume of 25 mL, and the absorbance was measured at 540 nm. The glucose content at 20 min and 120 min was labeled as G. 20 G 120 The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) are calculated as follows:

[0054] RDS (%) = (G 20 -F)×0.9 / T×100

[0055] SDS (%) = (G 120 -G20)×0.9 / T×100

[0056] RS(%)=100%-(RDS(%)+SDS(%))

[0057] In the formula, G 20 G 120 The values ​​represent the glucose content at 20 and 120 min of hydrolysis, respectively; F represents the free glucose content; and T represents the starch mass.

[0058] Figure 6 This image shows the in vitro digestion curves and nutrient composition graphs of resistant starch from jackfruit seeds after treatment with plasma-activated water and ultrasound. Figure A shows the in vitro digestion curve, and Figure B shows the nutrient composition graph. Figure 6 It can be seen that under plasma-activated water and ultrasonic treatment, the RS content of jackfruit seed starch gradually decreased with increasing ultrasonic power and treatment time. Under the same conditions, the RS content of the complex increased relatively. When the ultrasonic power was 600 W and the treatment time was 30 min, the RS and RDS contents of the complex P-U600-30-G reached their maximum and minimum values ​​of 77.258% and 18.426%, respectively.

[0059] The in vitro digestion curves showed that the digestibility of all samples initially increased rapidly and then stabilized with increasing digestion and hydrolysis time. The digestion curves of starch samples showed an upward trend with increasing ultrasonic power and duration, possibly because the synergistic treatment of plasma-activated water and ultrasound created micropores and cracks on the surface of starch granules, making them easier for amylases to contact and decompose. Simultaneously, the active substances in the plasma-activated water may have cleaved the long chains of starch molecules, generating more short-chain starch, which is more easily hydrolyzed by enzymes. Under the action of plasma-activated water and ultrasound, the V-shaped complex formed by jackfruit seed starch and gallic acid significantly reduced digestibility. This is partly due to the compact rearrangement of the double helix structure in starch granules caused by plasma-activated water and ultrasound treatment, thus reducing the starch hydrolysis rate. Furthermore, the presence of gallic acid protects starch molecules from digestive enzymes, thereby inhibiting the digestion of the polyphenol-starch complex. Moderate ultrasonic treatment (300 W, 15 min) significantly increased the formation rate of the starch-polyphenol complex, while high-intensity ultrasound (600 W, 30 min) led to complex dissociation and functional decline.

[0060] The effect of synergistic treatment of plasma-activated water and ultrasound on resistant starch from jackfruit seeds is closely related to the time and power of the ultrasound treatment. The optimal conditions for preparing resistant starch by synergistic treatment of plasma-activated water and ultrasound are an ultrasound power of 600W and a time of 30 min, under which the combined effect is the best. After synergistic treatment, the particle size of the composite increases, the surface roughness increases, and the crystal form of the composite changes from C+V type to V type crystal, while its relative crystallinity decreases.

[0061] This invention provides a method for preparing resistant starch from jackfruit seeds based on ultrasonic treatment. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing resistant starch from jackfruit seeds based on ultrasonic treatment, characterized in that, The process includes the following steps: mixing jackfruit seed starch and plasma-activated water evenly to obtain a starch solution; gelatinizing the starch solution by ultrasonic treatment, then adding gallic acid, stirring evenly, compounding by shaking, cooling, drying, and sieving to obtain the jackfruit seed resistant starch; The ultrasonic treatment is performed under the following conditions: power 300~600 W, frequency 40 Hz, and time 30~60 min.

2. The preparation method according to claim 1, characterized in that, The ultrasonic treatment was performed under the following conditions: power 600 W, frequency 40 Hz, and time 30 min.

3. The preparation method according to claim 1, characterized in that, The mass-to-volume ratio of the jackfruit seed starch to the plasma-activated water is 1 g: 10 mL.

4. The preparation method according to claim 1, characterized in that, The gelatinization is performed under the following conditions: gelatinization is carried out in a boiling water bath for 20 minutes.

5. The preparation method according to claim 1, characterized in that, The amount of gallic acid added is 10% of the mass of jackfruit seed starch.

6. The preparation method according to claim 1, characterized in that, The conditions for the composite process are: a shaking speed of 150 r / min, a temperature of 100 ℃, and a time of 1.5 h.

7. The resistant starch of jackfruit seeds prepared by the preparation method according to any one of claims 1 to 6.

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