Quantitative characterization method for short-range order of gelatinized starch and application

Abstract

The application provides a quantitative characterization method and application of short-range order of gelatinized starch, and comprises the following steps: (1) preparation of amorphous starch; (2) preparation of gelatinized starch with different short-range orders; (3) detection of the amorphous starch and the gelatinized starch respectively, peak fitting is performed on the obtained X-ray diffraction spectrum, and a linear relationship of water content, intensity of 2theta peak, relative peak area and half-peak width is obtained. The quantitative characterization method and application of short-range order of gelatinized starch provided by the application firstly prepares amorphous starch and gelatinized starch, then analyzes the difference between the X-ray diffraction patterns of the amorphous starch and the gelatinized starch, finds the characteristic diffraction peak of the short-range order of the gelatinized starch for the first time, and uses the relative peak area ratio of the characteristic peak to represent the content of the short-range order structure in the gelatinized starch. The method has potential wide application in the fields of food, chemical industry or medicine.

Description

Technical Field

[0001] This invention belongs to the field of polymer chemistry, and in particular relates to a quantitative characterization method and application of short-range ordering of gelled starch. Background Technology

[0002] Starch is widely found in the seeds, roots, and tubers of various crops such as wheat, potatoes, and rice, and is an important raw material for both the food and non-food industries. Beyond food, starch is also widely used in biomedicine, biodegradable materials, and papermaking. Natural starch possesses a complex multi-scale structure, which can be divided into several levels from smallest to largest: glucose units, double helix structures, lamellar structures, superhelical structures, microstructures, semi-crystalline growth ring structures, and starch granules. The multi-scale structure of starch can be characterized using various techniques. On one hand, the long-range molecular order of starch represents its crystallinity, typically characterized by X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS). On the other hand, the short-range molecular order of starch reflects the local helical structure arrangement, and can be characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). The multi-scale structure of starch is a key factor influencing its functional and nutritional properties in food processing. For example, the digestibility and degree of digestibility of processed starch largely depend on the content of the ordered structure remaining after processing.

[0003] In most industrial applications, semi-crystalline starch granules are typically gelatinized or plasticized into an amorphous form. Gelated or plasticized starches lacking X-ray diffraction peaks or differential scanning calorimetry (DSC) endothermic peaks are considered to have lost their long-range ordered structure but still contain some residual short-range ordered structures. To date, there is insufficient understanding of these short-range ordered structures in gelled / plasticized starches, and even their definition remains unclear. In our previous research, we considered short-range order in gelled starches to be partially unwound double helices, independent double helices, or small clusters of double helices. The residual short-range ordered structures in gelled or plasticized starches are considered important determinants of the functional properties of gelled / plasticized starches and the performance of starch-based products. However, currently only we have developed a qualitative characterization method for the short-range ordered structure in gelled starches; quantitative characterization methods have not yet been reported. Our qualitative characterization method revealed that the degree of residual short-range molecular order in gelled starches significantly affects retrogradation, gel properties, and in vitro enzymatic digestion. However, qualitative characterization methods cannot understand the correlation between structure and function in processed starch from quantitative indicators, and therefore cannot provide good theoretical guidance for the quality or functional control of processed starch or starch products. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the deficiencies in the prior art and propose a quantitative characterization method for the short-range order of gelled starch and its application.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A quantitative characterization method for the short-range ordering of gelled starch includes the following steps:

[0007] (1) Preparation of amorphous starch: starch is added to deionized water and mixed to obtain a starch-water mixture. The starch-water mixture is allowed to stand and then heated to obtain a gelled starch paste. The gelled starch paste is freeze-dried to obtain the amorphous starch.

[0008] (2) Preparation of starches with different short-range ordered gelation: starch is added to deionized water and mixed to obtain a starch-water mixture. The starch-water mixture is allowed to stand, then heated, flattened, and freeze-dried to obtain the starches with different short-range ordered gelation.

[0009] (3) The amorphous starch and the different short-range ordered gelled starches are tested, and the obtained X-ray diffraction patterns are fitted by peak division to obtain the linear relationship between water content and the intensity, relative peak area and half peak width of the 2θ peak.

[0010] After the sample to be tested is made into a block sample with a flat surface, X-ray diffraction is performed to obtain an X-ray diffraction pattern. The intensity and half-width of the 2θ peak are substituted into the linear relationship in step (3) to obtain the relative peak area of ​​the 2θ peak, which is the content of the short-range ordered structure of the sample to be tested.

[0011] Further, the starch in step (1) may be the same as or different from the starch in step (2); the starch in step (1) is at least one of type A, B, or C starch; preferably, the starch in step (1) is at least one of wheat starch, potato starch, corn starch, yam starch, or rice starch; the starch in step (2) is at least one of type A, B, or C starch; preferably, the starch in step (2) is at least one of wheat starch, potato starch, corn starch, yam starch, or rice starch. Further, the moisture content of the starch-water mixture in step (1) is 95-99% (w / w).

[0012] Furthermore, the heating step in step (1) is at a temperature of 120-130°C and a time of 30-60 minutes.

[0013] Furthermore, the moisture content of the starch-water mixture in step (2) is 70-95% (w / w).

[0014] Furthermore, the heating step in step (2) is at a temperature of 80-100℃ and a time of 2-10 minutes.

[0015] Furthermore, the conditions for the detection step in step (2) are: working voltage of 40kV, working current of 40mA, scanning rate of 2° / min, step size of 0.06°, and scanning range of 5 to 50°.

[0016] Furthermore, in step (3), 2θ is 5 to 50°.

[0017] Furthermore, the peak fitting step in step (3) is specifically as follows: first, linear baseline correction is performed, and then a Gaussian function is selected as the fitting function; the relative peak area of ​​the 2θ peak in step (3) is equal to the area of ​​the 2θ peak / the area of ​​all diffraction peaks.

[0018] An application of a quantitative characterization method for the short-range ordering of gelled starch, wherein the quantitative characterization method is applied in the food, chemical or pharmaceutical fields.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The quantitative characterization method for short-range ordering of gelled starch described in this invention involves: firstly, preparing amorphous starch and gelled starch; then, by analyzing the differences in X-ray diffraction patterns between amorphous and gelled starch, identifying for the first time the characteristic diffraction peaks of short-range ordering in gelled starch; and using the relative peak area ratio of the characteristic peaks to describe the content of short-range ordered structures in gelled starch. This provides a methodological basis for a deeper understanding of the correlation between the short-range ordered structure and functional properties of gelled or plasticized starch in processed starchy foods and other products.

[0021] The quantitative characterization method for short-range ordering of gelled starch described in this invention is applicable to A-, B-, and C-type starches, laying a theoretical foundation for better studying the correlation between the structure and functional properties of gelled or plasticized starches. Attached Figure Description

[0022] Figure 1 The XRD pattern of the gelled starch described in Example 1 of this invention;

[0023] Figure 2 The XRD pattern of the gelled starch described in Example 2 of this invention;

[0024] Figure 3 shows the peak fitting curves of the XRD curves of gelled starch and amorphous starch described in Example 1 of the present invention: 3-A is gelled wheat starch, and 3-B is amorphous wheat starch.

[0025] Figure 4 shows the peak fitting curves of the XRD curves of gelled starch and amorphous starch described in Example 2 of the present invention: 4-A is gelled potato starch, and 4-B is amorphous potato starch.

[0026] Figure 5 shows the relationship between the peak intensity, relative peak area, and half-peak width at 33° (2θ) of the gelled starch X-ray diffraction peak in Example 1 of the present invention and the water content: 5-A is the intensity at 33° (2θ), 5-B is the relative peak area, and 5-C is the half-peak width.

[0027] Figure 6 shows the relationship between the peak intensity, relative peak area, and half-peak width at 33° (2θ) of the gelled starch X-ray diffraction peak of Example 2 of the present invention and the water content: 6-A is the intensity at 33° (2θ), 6-B is the relative peak area, and 6-C is the half-peak width. Detailed Implementation

[0028] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0029] The present invention will be described in detail below with reference to the embodiments.

[0030] Example 1

[0031] A quantitative characterization method for the short-range ordering of gelled starch and its application, comprising the following steps:

[0032] (1) Preparation of amorphous wheat starch samples

[0033] Wheat starch and water were prepared into starch-water mixtures with moisture contents of 95%, 96%, 97%, 98%, and 99% (w / w), respectively. The mixtures were heated in an autoclave at 121°C for 30 minutes and then left to stand for 2 hours to allow the starch and water to fully contact. The gelled starch paste was then transferred to a glass petri dish and freeze-dried to obtain a block sample (WS-121-XX). Amorphous starch samples were obtained by Raman spectroscopy analysis.

[0034] (2) Preparation of gelled wheat starch samples with different short-range order

[0035] Wheat starch and water were prepared into starch-water mixtures with moisture contents of 70%, 75%, 80%, 85%, 90%, and 95% (w / w). The mixtures were left to stand for 2 hours to allow the starch and water to mix thoroughly. Then, the mixtures were heated in a water bath at 80°C for 5 minutes. Immediately after heating, the samples were removed, poured into petri dishes, carefully flattened, and freeze-dried to obtain gelled samples with different short-range order properties (WS-80-XX). The short-range order properties of the gelled starch were qualitatively analyzed by Raman spectroscopy.

[0036] (3) The obtained amorphous starch and gelled starch were characterized by X-ray diffraction. The test conditions were: working voltage of 40 kV, working current of 40 mA, scanning rate of 2° / min, step size of 0.06°, and scanning range of 5–50° (2θ). The results were linearly baseline corrected, and Gaussian function was selected for peak fitting. The intensity, relative peak area, and half-peak width at 33° (2θ) were calculated. The formula for calculating the relative peak area was: relative peak area of ​​33° (2θ) peak = area of ​​33° (2θ) peak / area of ​​all diffraction peaks.

[0037] Example 2

[0038] A quantitative characterization method for the short-range ordering of gelled starch and its application, comprising the following steps:

[0039] (1) Preparation of amorphous potato starch samples

[0040] Potato starch and water were prepared into starch-water mixtures with moisture contents of 95%, 96%, 97%, 98%, and 99% (w / w), respectively. After heating at 121°C for 30 minutes in an autoclave, the gelled starch paste was transferred to a glass petri dish and freeze-dried to obtain a block sample (PS-121-XX). Amorphous starch samples were obtained by Raman spectroscopy analysis.

[0041] (2) Preparation of gelled potato starch samples with different short-range order

[0042] Potato starch and water were prepared into starch-water mixtures with moisture contents of 70%, 75%, 80%, 85%, 90%, and 95% (w / w). The mixtures were left to stand for 2 hours to allow the starch and water to fully contact each other, and then heated in a water bath at 100°C for 5 minutes. Immediately after heating, the samples were removed, poured into petri dishes, carefully flattened, and freeze-dried to obtain gelled samples with different short-range order (PS-100-XX). The short-range order of the gelled starch was qualitatively analyzed by Raman spectroscopy.

[0043] (3) The obtained amorphous starch and gelled starch were characterized by X-ray diffraction. The test conditions were: working voltage of 40 kV, working current of 40 mA, scanning rate of 2° / min, step size of 0.06°, and scanning range of 5–50° (2θ). The results were linearly baseline corrected, and Gaussian function was selected for peak fitting. The intensity, relative peak area, and half-peak width at 33° (2θ) were calculated. The formula for calculating the relative peak area was: relative peak area of ​​33° (2θ) peak = area of ​​33° (2θ) peak / area of ​​all diffraction peaks.

[0044] The test results are as follows:

[0045] 1. Samples prepared in an autoclave were analyzed using an Invia laser confocal Raman spectrometer (Renishaw, UK) (as shown in Table 1). The test results indicate that as the moisture content increases from 95% to 98%, wheat and potato starch at 480 cm⁻¹... -1 The intensity and area of ​​the Raman bands decreased to their limiting values ​​and showed no further change at 99% moisture content. Based on the method of qualitatively characterizing the short-range molecular sequence in gelled starch using Raman spectroscopy, the Raman bands at 480 cm⁻¹... -1 The limit value indicates that the short-range molecular sequence has not changed further, therefore the starch sample with 99% water content is considered to be completely gelled and amorphous, with no residual short-range molecular sequence.

[0046] Table 1. Starch samples prepared by autoclave at 480 cm⁻¹ -1 Intensity and area of ​​the Raman band at the location

[0047]

[0048] 2. Samples prepared in a water bath were analyzed using an Invia laser confocal Raman spectrometer (Renishaw, UK). The spectra at 480, 854, 934, 1080, and 1334 cm⁻¹ were analyzed. -1 The area and intensity of the five main Raman bands at the site. The area and intensity of the Raman bands of gelled wheat and potato starch decreased with increasing moisture content, indicating that the short-range order of gelled starch decreased from 70% to 95% moisture.

[0049] 3. X-ray diffractometer (D8 Advance) from Bruker, Germany was used to detect gelled starch and amorphous starch with different short-range order (e.g., ...). Figures 1-2(As shown). The results showed that typical type A crystals in wheat starch and type B crystals in potato starch were not detected, indicating that the long-range ordered structure in these two types of gelled starches was completely destroyed. After linear baseline correction of the XRD patterns of the gelled starches and fitting with a Gaussian function, five diffraction peaks at 13, 19, 20, 33, and 44° (2θ) were clearly identified (as shown). Figure 3-A Conversely, for amorphous starch samples, only four diffraction peaks were identified besides 33° (2θ) (e.g., Figure 3-B Similar results were observed with potato starch. Gelatinized potato starch exhibited five diffraction peaks at 13, 16, 20, 33, and 44° (2θ) (e.g., Figure 4-A ), while no diffraction peak was observed at 33° (2θ) for amorphous starch (e.g. Figure 4-B The above results indicate that the diffraction peak at 33° (2θ) is a characteristic peak of gelled starch.

[0050] Therefore, the 33°(2θ) diffraction peak will be used to analyze the relationship between moisture content and diffraction peak parameters. The intensity, relative peak area, and half-width at 33°(2θ) of gelled starch are shown. For wheat starch, the functions of intensity, relative peak area, and half-width at 33°(2θ) with moisture content are as follows: Figure 5-A , Figure 5-B and Figure 5-C As shown. Water content and the intensity (R) of the 33°(2θ) peak. 2 =0.93), relative peak area (R) 2 =0.98) and half-width at half maximum (R) 2 =0.65) showed a negative correlation. Similar results were observed with potato starch ( Figure 6-A , 6-B (and 6-C). Therefore, we propose that the short-range order of gelled starch can be represented by intensity, half-width at half-maximum (HWHM), and the relative peak area of ​​the 33°(2θ) diffraction peak. Furthermore, the proportion of short-range ordered structures in gelled starch is reflected by calculating the ratio of the 33°(2θ) diffraction peak area to the total area of ​​all diffraction peaks—the relative peak area of ​​the 33°(2θ) diffraction peak. According to this definition, as the moisture content increases from 70% to 95%, the proportion of short-range ordered structures in gelled wheat and potato starch decreases from 39.7% to 25.2% and from 43.3% to 27.9%, respectively (as shown in Table 2).

[0051] Table 2. Diffraction intensity, relative peak area, and full width at half maximum (FWHM) of the gelled starch samples at the X-ray diffraction peak 33° (2θ).

[0052]

[0053] Based on the analysis of the above test data and results, this invention provides a quantitative characterization method and application for the short-range ordering of gelled starch. Compared with existing qualitative analysis methods, this method represents a breakthrough from qualitative to quantitative analysis. Furthermore, by preparing amorphous starch samples, XRD characteristic peaks of short-range ordering in gelled starch were discovered for the first time, providing a methodological basis for the quantitative analysis of the short-range ordered structure in gelled starch. This invention pioneers a quantitative characterization method for the short-range ordered structure of gelled starch, providing a methodological basis for a deeper understanding of the correlation between the short-range ordered structure and functional properties of gelled or plasticized starch in processed starch foods and other products.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for quantitative characterizing the short-range order of gelled starch, characterized in that: Includes the following steps: (1) Preparation of amorphous starch: starch is added to deionized water and mixed to obtain a starch-water mixture. The starch-water mixture is allowed to stand and then heated to obtain a gelled starch paste. The gelled starch paste is freeze-dried to obtain the amorphous starch. (2) Preparation of starches with different short-range ordered gelation: starch is added to deionized water and mixed to obtain a starch-water mixture. The starch-water mixture is allowed to stand, then heated, flattened, and freeze-dried to obtain the starches with different short-range ordered gelation. (3) The amorphous starch and the gelled starch are tested, and the obtained X-ray diffraction pattern is fitted by peak division to obtain the linear relationship between water content and the intensity, relative peak area and half peak width of the 2θ peak. The moisture content of the starch-water mixture in step (1) is 95-99 w / w % %. The moisture content of the starch-water mixture in step (2) is 70-95 w / w % %. The peak fitting step in step (3) is as follows: first, linear baseline correction is performed, and then the fitting function is selected as a Gaussian function; the intensity of the 2θ peak, the relative peak area, the intensity at half-width of 33° (2θ), the relative peak area and the half-width of 33° (2θ) in step (3) are calculated as follows: the relative peak area of ​​the 33° (2θ) peak = the area of ​​the 33° (2θ) peak / the area of ​​all diffraction peaks.

2. The method for quantitative characterization of short-range ordering of gelled starch according to claim 1, characterized in that: The starch in step (1) may be the same as or different from the starch in step (2); the starch in step (1) is at least one of type A, B, or C starch.

3. The method for quantitative characterization of short-range ordering of gelled starch according to claim 2, characterized in that: The starch in step (1) is at least one of wheat starch, potato starch, corn starch, yam starch or rice starch; the starch in step (2) is at least one of type A, B or C starch.

4. The method for quantitative characterizing the short-range order of gelled starch according to claim 2, characterized in that: The starch in step (2) is at least one of wheat starch, potato starch, corn starch, yam starch or rice starch.

5. The method for quantitative characterization of short-range ordering of gelled starch according to claim 1, characterized in that: The heating step in step (1) is at a temperature of 120-130℃ and a time of 30-60 min.

6. The method for quantitative characterization of short-range ordering of gelled starch according to claim 1, characterized in that: The heating step in step (2) is at a temperature of 80-100℃ and a time of 2-10 min.

7. The method for quantitative characterization of short-range ordering of gelled starch according to claim 1, characterized in that: The conditions for the detection step in step (2) are: working voltage of 40 kV, working current of 40 mA, scanning rate of 2° / min, step size of 0.06°, and scanning range of 5~50°.

8. The method for quantitative characterization of short-range ordering of gelled starch according to claim 1, characterized in that: In step (3), 2θ is 5~50°.

9. An application of a quantitative characterization method for the short-range ordering of gelled starch, characterized in that: The quantitative characterization method described herein has applications in the food, chemical, or pharmaceutical fields.

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