阅读说明：本技术 快速检测稻谷黄变的方法 (Method for rapidly detecting rice yellowing ) 是由 周中凯 肖悦 刘敏 戴真 于 2019-09-05 设计创作，主要内容包括：本发明属于食品检测领域,具体涉及一种快速检测稻谷黄变的方法,包括下述步骤：1)将黄变米和普通大米分别用浓硫酸水溶液浸泡处理,干燥后,用高速多功能粉碎机将样品研磨成粉末,以备实验使用。2)通过广角X-射线衍射和小角X-射线散射进行检测；3)利用origin9.0软件进行做图分析,利用jade6.0进行样品得广角X-射线衍射结晶度计算分析。该方法是一种准确、操作简便的检测黄变与正常稻谷中结构差异的方法,即可以检测黄变米,也可以检测正常大米以及储藏了一段时间以后的大米内部结构的结晶性质,为黄变大米提供进一步的研究基础。(The invention belongs to the field of food detection, and particularly relates to a method for rapidly detecting rice yellowing, which comprises the following steps: 1) respectively soaking the yellow rice and the common rice with concentrated sulfuric acid aqueous solution, drying, and grinding the sample into powder by using a high-speed multifunctional grinder for experimental use. 2) Detecting by wide angle X-ray diffraction and small angle X-ray scattering; 3) performing mapping analysis by using origin9.0 software, and performing wide-angle X-ray diffraction crystallinity calculation analysis on the sample by using jade 6.0. The method is accurate and simple to operate, can detect the structural difference between the yellow rice and the normal rice, can detect the yellow rice, and can also detect the crystallization properties of the internal structures of the normal rice and the rice after being stored for a period of time, thereby providing a further research basis for the yellow rice.)

1. A method for rapidly detecting the yellowing of rice is characterized by comprising the following steps:

1) respectively soaking yellow rice and common rice in concentrated sulfuric acid aqueous solution for 72h, and requiring the solution to submerge the sample; after the sample was soaked, the acid on the surface was washed with distilled water and then dried in a fume hood for 3 hours; after drying, grinding the sample into powder by using a high-speed multifunctional grinder for experimental use;

2) detecting by wide angle X-ray diffraction and small angle X-ray scattering;

3) performing mapping analysis by using origin9.0 software, and performing wide-angle X-ray diffraction crystallinity calculation analysis on the sample by using jade 6.0.

2. The method for rapidly detecting yellowing of rice as claimed in claim 1, wherein the concentration of the concentrated sulfuric acid aqueous solution in step 1) is 0.1mol/L to 1.0 mol/L.

3. The method for rapidly detecting yellowing of rice as claimed in claim 1, wherein the detection conditions of wide-angle X-ray diffraction in step 2) are as follows: wide-angle X-ray diffraction measurements Using an X-ray diffractometer, k value 1.54040, operating at 30kv acceleration potential and 20m current with copper target; the scanning range is 2 theta value of 5-35 deg., the scanning speed is 2 deg. 2 theta/min, and the sample amount is 1.5-2 g.

4. The method for rapidly detecting yellowing of rice as claimed in claim 1, wherein the small-angle X-ray scattering measurement conditions in step 2) are as follows: CuK alpha radiation with the wavelength of 0.1542nm at 50mA and 40kV is used as an X-ray source; preparing 60% starch slurry and balancing at 26 deg.C for 24 hr for reuse; each sample was filled into a pasty cell and measured by an incident X-ray monochromatic beam for 10 minutes.

Technical Field

The invention belongs to the field of food detection, and particularly relates to a method for rapidly detecting rice yellowing.

Background

The paddy is widely planted in the world, more than 60 percent of population takes the paddy as staple food, and the paddy is also the first large grain crop in China and is the most main consumer variety in the grain; when the rice is stored in a high-temperature and high-humidity environment, rice grains are easy to be changed into yellow, light yellow or gray orange locally or wholly, namely, the rice is yellowed after being picked (Postharvestyellowing), and the yellowing (PHY) of the rice is a worldwide problem and can cause the quality and the function of the rice to be reduced, so that the economic value of the rice is reduced. After the rice is yellow, the rice can not be eaten, but sometimes the fact that whether the rice is yellow can not be easily judged only from the appearance, and at the present stage, an effective means and a method for detecting whether the rice is yellow are not provided.

Disclosure of Invention

The invention aims to provide a method for rapidly detecting the yellowing of rice.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for rapidly detecting the yellowing of rice comprises the following steps:

1) respectively soaking yellow rice and common rice in concentrated sulfuric acid aqueous solution for 72h, and requiring the solution to submerge the sample; after the sample was soaked, the acid on the surface was washed with distilled water and then dried in a fume hood for 3 hours; after drying, the samples were ground to a powder using a high speed multifunction grinder for experimental use.

2) Detecting by wide angle X-ray diffraction and small angle X-ray scattering;

3) performing mapping analysis by using origin9.0 software, and performing wide-angle X-ray diffraction crystallinity calculation analysis on the sample by using jade 6.0.

The concentration of the concentrated sulfuric acid aqueous solution in the step 1) is 0.1-1.0 mol/L.

The detection conditions of the wide-angle X-ray diffraction in the step 2) are as follows: wide-angle X-ray diffraction measurements Using an X-ray diffractometer, k value 1.54040, operating at 30kv acceleration potential and 20m current with copper target; the scanning range is 2 theta value of 5-35 deg., the scanning speed is 2 deg. 2 theta/min, and the sample amount is 1.5-2 g.

The small-angle X-ray scattering measurement conditions in the step 2) are as follows: CuK alpha radiation with the wavelength of 0.1542nm at 50mA and 40kV is used as an X-ray source; preparing 60% starch slurry and balancing at 26 deg.C for 24 hr for reuse; each sample was filled into a pasty cell and measured by an incident X-ray monochromatic beam for 10 minutes.

Compared with the prior art, the invention has the beneficial effects that:

at present, researches on the yellowing aspect of rice mainly focus on the reasons causing yellowing and how to prevent yellowing, and the difference of the yellowing rice and normal rice in the aspect of results is not reported. The application uses sulfuric acid to carry out the preliminary treatment to the corn, and the sulfuric acid solution can provide two protons, and has sulfate radical and material reaction, and volatility is relatively weak in addition, so the reaction system is relatively stable, gets into the material inside rather than the reaction is relatively abundant. After the normal rice and the yellow rice are treated by the sulfuric acid, the structural difference between the normal rice and the yellow rice is enlarged, and whether the sample is yellow or not can be judged. The present study used a detection method combining wide angle X-ray diffraction with small angle X-ray scattering to detect sulfated compound treated rice to demonstrate the crystallization characteristics of yellowed rice. The method is accurate and simple to operate, can detect the structural difference between the yellow rice and the normal rice, can detect the yellow rice, and can also detect the crystallization properties of the internal structures of the normal rice and the rice after being stored for a period of time, thereby providing a further research basis for the yellow rice.

Drawings

FIG. 1 is a wide angle X-ray diffraction contrast plot of yellow rice versus normal rice using origin9.0 software;

FIG. 2 is a small angle X-ray scatter plot made using origin 9.0.

Detailed Description

In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and preferred embodiments.

The sample raw material method comprises the following steps:

weighing 30g of non-glutinous rice, yellow rice of long-shaped rice and common rice in a culture dish, weighing each sample for three times, then respectively adding the samples into concentrated sulfuric acid solutions of 0.1mol/L, 0.5mol/L and 1.0mol/L, and soaking for 72 hours, wherein the solution is required to be over the samples. After the sample was soaked for 72h, the acid on its surface was washed with distilled water and then dried in a fume hood for 3 hours. After drying, the sample is ground into powder by a high-speed multifunctional grinder, and in order to avoid the influence of high temperature of the grinder, the grinding is stopped every 10 seconds and is continued after the temperature of the outer wall of the instrument is reduced to normal temperature. The ground sample (not sieved) was placed in a self-sealing bag and stored in a desiccator.

The crystallinity and crystal type were measured using an X-ray diffractometer (D8, ADVANCES), with a k value of 1.54040, operating at an acceleration potential of 30kv and a current of 20m with a copper target. The scanning range is 2 theta value of 5-35 DEG, and the scanning speed is 2 DEG 2 theta/min. 1.5g of the sample was accurately weighed, placed in a measuring pan, pressed flat with weighing paper, and then measured. The crystal forms of different samples can be visually displayed by X-ray diffraction, the crystallinity of each sample can be obtained by processing the samples by jade6.0 software, and the crystallinity is an important index for representing the structural characteristics of different samples.

SAXS is equipped with PW 3830X-ray generator. CuK alpha radiation having a wavelength of 0.1542nm at 50mA and 40kV was used as X-ray source. Starch slurry (about 60%) was prepared and used after 24 hours of equilibration at 26 ℃. Each sample was filled into a pasty cell and measured by an incident X-ray monochromatic beam for 10 minutes. Data were recorded using an image plate and collected by a Perkin Elmer storage phosphor system using IP reader software. All SAXS data were calibrated against normalized background scatter of the main beam intensity and background intensity and blur intensity were removed using SAXS quant 3.0 software for further analysis.

Starch granules exhibit a distinct characteristic scattering peak at 0.6-0.7nm, which is characteristic of semicrystalline lamellar structures. It can be seen that according to the Woolf-Bragg formula d is 2 Π/q, the characteristic peak is from 0.6nm to 0.7nm, and the corresponding layer structure has a thickness of from 9 to 10 nm.

Example one: the crystallinity of normal rice and yellow rice of both japonica and indica varieties was measured using an X-ray diffractometer (D8, ADVANCES).

Example two: the crystallinity of normal rice and yellow rice of both japonica and indica varieties was measured using an X-ray diffractometer (D8, ADVANCES) (samples were treated with a 0.1mol/L sulfuric acid solution).

Example three: the crystallinity of normal rice and yellow rice of both japonica and indica varieties was measured using an X-ray diffractometer (D8, ADVANCES) (samples were treated with a 0.5mol/L sulfuric acid solution).

Example four: the crystallinity of normal rice and yellow rice of both japonica and indica varieties was measured using an X-ray diffractometer (D8, ADVANCES) (samples were treated with 1.0mol/L sulfuric acid solution).

Example five: the crystallinity of normal rice and yellow rice of japonica rice and long-shaped rice is measured by using a SAXS small-angle scatterometer.

Example six: the crystallinity of normal rice and yellow rice of both japonica rice and indica rice varieties was measured using a SAXS small angle scatterometer (samples were treated with 1.0mol/L sulfuric acid solution).

Example seven: the crystallinity of normal rice and yellow rice of both japonica rice and indica rice varieties was measured using a SAXS small angle scatterometer (samples were treated with 1.0mol/L sulfuric acid solution).

Example eight: the crystallinity of normal rice and yellow rice of both japonica rice and indica rice varieties was measured using a SAXS small angle scatterometer (samples were treated with 1.0mol/L sulfuric acid solution).

Table 1 shows the crystallinity of the yellow rice and the normal rice calculated using the jade6.0 software;

TABLE 1

The difference in wide angle X-ray diffraction between normal rice and PHY is shown in fig. 1. The three concentrations of sulfuric acid solution treatment did not change the crystal pattern of regular rice and PHY and all samples showed "type a" crystals, i.e., diffraction angles 2 θ had a single diffraction peak at 15 °, 20 ° and 23 ° and a contiguous double diffraction peak at 17 ° and 18 °. It was observed that the PHY crystallinity was higher than that of the corresponding ordinary rice after the treatment with the 0.1mol/L sulfuric acid solution, and these results were consistent with the original normal and PHY crystallization characteristics of rice. For samples treated by 0.5mol/L and 1.0mol/L sulfuric acid solutions, the crystallinity of all PHY rice is obviously lower than that of common rice, and whether the samples are yellowing samples can be judged by calculating the crystallinity of the samples.

Wherein, in the figure 1(a), a rice sample is treated by 0.1mol/L concentrated sulfuric acid solution; (b) treating a rice sample by using 0.5mol/L concentrated sulfuric acid solution; (c) treating a rice sample by using 1.0mol/L concentrated sulfuric acid solution; (d) samples not treated with a sulfuric acid solution.

FIG. 2(a1) shows normal and yellow polished round-grained rice; (b1) non-glutinous rice normal rice and yellow rice; (a2) normal rice and yellow rice of polished round-grained rice treated by 0.1mol/L concentrated sulfuric acid solution; (a3) non-glutinous rice normal rice and yellow rice treated by 0.1mol/L concentrated sulfuric acid solution; (a4) normal rice and yellow rice of polished round-grained rice treated by 0.5mol/L concentrated sulfuric acid solution; (b2) normal rice and yellow rice of polished round-grained rice treated by 0.5mol/L concentrated sulfuric acid solution; (b3) normal rice and yellow rice of polished round-grained rice treated by 1.0mol/L concentrated sulfuric acid solution; (b4) normal rice and yellow rice of polished round-grained rice treated by 1.0mol/L concentrated sulfuric acid solution.

The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.