CN104062309A - Method for measuring relative crystallinity of starch - Google Patents

Abstract

The invention relates to a method for measuring the relative crystallinity of starch. This method obtains the XRD spectrum of the starch sample to be analyzed; the XRD spectrum is processed with Photoshop software, and the regions of crystalline peaks and non-crystalline peaks are marked with Photoshop software, selected and filled with different grayscale colors, and the images are saved. Open the image to be processed with Image-Pro Plus software, complete the calculation of the area of the crystalline peak and the non-crystalline peak area, and then calculate the relative crystallinity accordingly. The invention has the advantages of simple operation, more accuracy and better controllability, and can reduce the error to the limit.

Description

A method for measuring the relative crystallinity of starch

technical field

The invention belongs to the technical fields of biological science and food science, and in particular relates to a method for measuring the relative crystallinity of starch.

Background technique

Starch crystallinity is an important parameter to characterize the crystallization properties of starch granules, and also an important parameter to characterize the properties of starch material products. Its size directly affects the application performance of starch products and the physical and mechanical properties of starch materials. In recent years, the rapid, simple and reliable determination of the crystallinity of starch and starch derivatives has attracted much attention from researchers at home and abroad. According to literature reports, X-ray diffraction (XRD) is one of the most commonly used methods for measuring the crystallinity of starch granules. Methods such as Herman method, Wakelin method and Zhang Benshan method can all measure the crystallinity of starch granules, but they all have their own characteristics. shortcoming. The demarcation of the crystalline region and the amorphous region in the Herman method is entirely based on experience, and the measurement is purely empirical, and it is very arbitrary. The two "standard samples" in the Wakelin method are not standard. The biggest disadvantage is that the measured crystallinity tends to be higher than the real crystallinity. However, in the data processing of this method, the diffraction intensity is subtracted. Many Scattering factors that affect the experiment disappear by themselves or do not need to be corrected. The Zhang Benshan method ignores the difference in the diffraction effect of X-rays on the crystalline region and the amorphous region and the influence of other scattering factors on the diffraction pattern, which leads to errors in the results.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention provides a method for measuring the relative crystallinity of starch. The method of analyzing starch XRD spectrum and calculating the relative crystallinity of starch by combining Photoshop and Image Pro-Plus software is very scientific and reasonable. and accuracy, which basically overcomes the shortcomings and deficiencies of the above determination methods.

A method for measuring the relative crystallinity of starch according to the present invention comprises the following steps:

(1) Obtain the XRD spectrum of the starch sample to be analyzed; process the XRD spectrum with Photoshop software, mark the areas of the crystalline peak and the non-crystalline peak and fill them with different grayscale colors respectively, and save the image;

(2) Open the image preserved in step (1) with Image-Pro Plus software, calculate crystallization peak and non-crystallization peak region area, then calculate relative crystallinity accordingly; Relative crystallinity=[crystallization peak area/(crystallization Peak area + non-crystalline peak area)] × 100%.

Wherein, in the step (1), the specific operation of Photoshop software processing XRD spectrogram is: draw a straight line at 4°-30° of the wave spectrum close to the base of the wave peak, and then draw a straight line at the bottom of the main crystalline peak and the baseline of the non-crystalline peak with the pen tool Add anchor points, use the conversion point tool to connect the smoothed curves of each anchor point, and then use the brush tool to stroke the path; finally use the magic wand tool to transform the crystalline peak above the smooth curve and the area of the non-crystalline peak between the curve and the straight line Select and fill with different grayscale colors, and save the image.

The specific method of calculating the area in step (2) is: click the count/size icon, in the count/size window, click select colors to select the crystallization peak area, the software will automatically identify the color of the area, and return to the count/size window after clicking close, In the menu, select Measure-selectmeasurements to select the area (Area), and click count after returning. At this time, the software has completed the calculation of the area of the crystallization peak area. Click view-statistics to get the area data. Similarly, the area of the non-crystalline peak region can be calculated.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The whole process is easy to operate, and ordinary scientific researchers can complete the operation with a little practice, which saves a lot of time compared with the previous general curve drawing method.

(2) The drawing of the curve uses the pen tool in Photoshop, which is more professional, more accurate and more manipulable than other tools.

(3) The color area selected by the magic wand tool is very specific, down to the pixel level, and there will be no loss of a certain area.

(4) The pipette tool of Image-Pro Plus software is used for color identification, which can ensure that the area of each area colored in advance can be accurately counted, and the error is reduced to the limit.

Description of drawings

Fig. 1 is wheat starch XRD spectrum;

Figure 2 is the spectrum of adding a straight line between 4°-30° with Photoshop software;

Figure 3 is the spectrum after adding anchor points;

Fig. 4 is the wave spectrum connecting each anchor point with a smooth curve;

Figure 5 is the spectrum of the stroke path with the brush tool;

Figure 6 is a spectrum filled with crystalline peak regions and non-crystalline peak regions with different grayscale colors;

Fig. 7 is to complete the crystallization peak area calculation;

Figure 8 is the statistical result of the crystallization peak area area;

Fig. 9 is to complete the calculation of the area of the amorphous peak area;

Figure 10 is the statistical result of the area of the amorphous peak area;

Fig. 11 is the operation process for calculating the relative crystallinity of starch.

Detailed ways

The specific operation process of the method is shown in Fig. 11 by using the wheat starch XRD spectrum as the material below:

1. XRD spectrum of wheat starch granules

The separated wheat starch was absorbed in a closed container filled with a saturated sodium chloride solution for one week, and then analyzed by a polycrystalline X-ray diffractometer (XRD). The spectrum is shown in Figure 1.

2. Use Photoshop CS4 software to draw a straight line close to the base of the wave peak at 4°-30° of the wave spectrum (Figure 2), and then use the pen tool in Photoshop to add anchor points at the bottom of each main crystalline peak and the baseline of the non-crystalline peak ( Figure 3), and then use the conversion point tool to connect each anchor point with a smooth curve (Figure 4), and use the brush tool to fill the path with a black line (Figure 5). Use the magic wand tool in the Photoshop menu to fill the area above the smooth curve and between the curve and the line with different gray-scale colors (Figure 6).

3. Open the processed spectrum with Image-Pro Plus software, select Measure-count/size in turn, in the count/size window, click select colors to select the color of the crystal peak area, the software will automatically identify the color area, click close Return to the count/size window, select Measure-select measurements in the menu to select the area (Area), and click count after returning. At this time, the software has completed the calculation of the area of the crystallization peak area (Figure 7), and click view-statistics to get the area data (Fig. 8), similarly the area of the blue area can be calculated (Fig. 9, Fig. 10).

4. Calculation of relative crystallinity of starch, relative crystallinity=[A1/(A1+A2)]×100%=[24482/(24482+45366)]×100%=35.05%.

Claims (3)

1. A method for measuring the relative crystallinity of starch, characterized in that it may further comprise the steps: (1) Obtain the XRD spectrum of the starch sample to be analyzed; process the XRD spectrum with Photoshop software, mark the areas of the crystalline peak and the non-crystalline peak and fill them with different grayscale colors respectively, and save the image; (2) Open the image preserved in step (1) with Image-Pro Plus software, calculate crystallization peak and non-crystallization peak region area, then calculate relative crystallinity accordingly; Relative crystallinity=[crystallization peak area/(crystallization Peak area + non-crystalline peak area)] × 100%. 2. method according to claim 1, it is characterized in that in the step (1), the concrete operation of Photoshop software processing XRD spectrogram is: 4 °-30 ° of wave spectrum draws a straight line close to the crest base, then with pen tool Add anchor points at the bottom of the main crystalline peak and the baseline of the non-crystalline peak, use the conversion point tool to connect the smoothed curves of each anchor point, and then use the brush tool to stroke the path; finally use the magic wand tool to smooth the crystal above the curve The peak and the area of the non-crystalline peak between the curve and the straight line were selected and filled with different gray-scale colors, and the image was saved. 3. The method according to claim 1, wherein the specific operation of calculating the area of the crystalline peak and the non-crystalline peak area in step (2) is: click on the count/size icon, and in the count/size window, click select Select the crystallization peak area in colors, the software will automatically recognize the color of the area, click close to return to the count/size window, select Measure-select measurements in the menu to select Area, and click count after returning, and the software has completed the area of the crystallization peak area For calculation, click view-statistics to get the area data; similarly, the area of the non-crystalline peak area can be calculated.