Some standard content:
National Standard of the People's Republic of China
Determination of amylose content in rice
Rice-Determination of amylose contentGB/T 15683—1995
This standard is equivalent to the international standard ISO6647:1987 "Rice-Determination of amylose content".
Subject content and scope of application
This standard specifies the determination method and result calculation of the amylose content in rice. This standard is applicable to the determination of the amylose content in rice. 2 Reference standards
GB5491 Sampling and sub-sampling method for inspection of grains and oilseeds GB5497 Determination of moisture content in inspection of grains and oilseeds GB5513 Determination of reducing sugar and non-reducing sugar in inspection of grains and oilseeds 3 Definitions
This standard adopts the following definitions:
3.1 Amylose: The polysaccharide component in starch, whose macromolecules have a distinct chain structure. 3.2 Amylopectin: a polysaccharide in starch, whose macromolecules have a branched structure. 4 Principle
Crush the rice into fine powder to destroy the crystalline structure of starch, making it easy to disperse and gelatinize completely, and defatt the crushed sample. The defatted sample is dispersed in a sodium hydroxide solution, and an iodine reagent is added to a certain amount of the sample dispersion. The absorbance of the formed complex is measured at 620nm.
Considering the effect of amylopectin on the iodine-amylose complex in the sample, a calibration curve is prepared using a mixture of amylose and amylopectin, and the amylose content in the sample is read from the calibration curve. 5 Reagents
Unless otherwise specified, all reagents used are analytically pure, and water is distilled water or water of at least the same purity. 5.1 Methanol (GB 683): 85% (V/V).
5. 2 Ethanol (GB 679): 95% (V/V). 5.3 Sodium hydroxide (GB629): 1 mol/L aqueous solution. 5.4 Sodium hydroxide (GB629): 0.09 mol/L aqueous solution, accurately calibrated. 5.5 Acetic acid (GB 676): 1 mol/L solution. 5.6 Iodine reagent: Weigh 2.000±0.005g potassium iodide (GB1272) in a weighing bottle with a cover, add appropriate amount of water to form a saturated solution, add 0.200±0.001g iodine (GB675), after the iodine is completely dissolved, transfer the solution quantitatively to a 100mL volumetric flask, add water to the scale, and shake well. Prepare it before use every day and store it away from light.
Approved by the National Technical Supervision Kitchen on August 17, 1995 474
Implemented on January 1, 1996
GB/T 15683—1995
5.7 Potato amylose standard solution: 1mg/mL. Weigh 100±0.5mg defatted and balanced amylose in a 100mL beaker, add 1.0mL anhydrous ethanol to moisten the sample, then add 9.0mL 1mol/L sodium hydroxide solution (5.3) and disperse in a 85℃ water bath for 10min, transfer to a 100mL volumetric flask, wash the beaker several times with 70mL water, transfer the washing liquid to the volumetric flask, add water to the scale, and shake vigorously. 1mL of this standard dispersion contains 1mg amylose. The preparation of potato amylose standard is shown in Appendix A (Supplement). 5.8 Pullulan standard solution: 1 mg/mL
Weigh 100 ± 0.5 mg of waxy rice pullulan after protein removal, defatting and equilibration into a 100 mL beaker, add 1.0 mL of anhydrous ethanol to moisten the sample, then add 9.0 mL of 1 mol/L sodium hydroxide solution (5.3), disperse in a water bath at 85°C, transfer to a 100 mL volumetric flask, wash the beaker several times with 70 mL of water, transfer the washing liquid to the volumetric flask, add water to the scale, and shake vigorously. 1 mL of this standard solution contains 1 mg pullulan. The preparation of the waxy rice pullulan standard product is shown in Appendix B (Supplement). 6 Instruments
Common instruments and special equipment in the laboratory:
6.1 Laboratory mill: can grind rice and pass it through an 80 mesh sieve. 6.2 Sieve: 80 mesh.
6.3 Laboratory mill.
6.4 Laboratory rice mill.
6.5 Spectrophotometer: with 1cm colorimetric blood, capable of measuring absorbance at 620nm. 6.6 Fat extractor: Soxhlet or Gooch.
6.7 Volumetric flask: 100mL.
6.8 Stoppered colorimetric tube: 50mLc
7 Sampling
Follow the provisions of GB5491.
8 Operating steps
8.1 Sample preparation
Use a grinder to grind at least 20 rice samples (rice samples should be shelled first, then the brown rice should be crushed), all of which should pass through an 80-mesh sieve, mix well, and put into a ground-mouth wide-mouth bottle for later use.
Extract the sample with methanol in a Soxhlet extractor for 4 h (rice with accuracy above the standard should be extracted for 2 h), or extract in a Gooch extractor for 2 h (5-6 drops/s), defat, and spread the sample in a dish and let it stand for 2 d to allow the residual methanol to evaporate and the water content to reach equilibrium. 8.2 Weighing the sample
Weigh 100±0.5 mg of the sample in a 100 mL beaker. 8.3 Sample solution
Use a pipette to carefully add 1.0 mL of anhydrous ethanol (5.2) to the sample portion (8.2), flush all the sample adhering to the wall of the cup, fully wet the sample, then use a pipette to add 9.0 mL of 1 mol/L sodium hydroxide solution (5.3), let it stand at room temperature for 15~24 hours to disperse the sample, or disperse it in an 85℃ water bath for 10~15 minutes, cool it quickly, transfer it to a 100 mL volumetric flask, wash the beaker with 70 mL of water 3~4 times, transfer the washing solution to the volumetric flask, add water to the scale, and shake it vigorously. 8.4 Test blank
During the determination, make a test blank at the same time, with the same operating steps and the same amount of reagents as used in the determination, but use 2.5 mL of 0.09 mol/L sodium hydroxide solution (5.4) instead of the sample solution. 475
8.5 Calibration curve drawing
8.5.1 Preparation of standard series solutions
GB/T 15683--1995
Mix a certain volume of standard dispersion of amylose and amylopectin and 2.0mL 0.09mol/L sodium hydroxide solution according to the following table. Composition of mixed solution, mL
Amylose content in rice, %
(kb)
Amylose
Amylopectin
Note: The above data are calculated on the basis of dry rice with an average starch content of 90% and 0.09mol/L sodium hydroxide
For routine analysis, defatted rice with pre-determined amylose content can be used instead of amylose dispersion for calibration. 8.5.2 Color development
Accurately transfer 2.5 mL of the standard series solution into a 50 mL colorimetric tube. Add 25 mL of water to the colorimetric tube in advance. Add 0.5 mL of 1 mol/L acetic acid solution (5.5), mix well, then add 1.0 mL of iodine reagent (5.6), add water to the scale, plug the tube, shake well, and let it stand for 20 minutes. 8.5.3 Absorbance determination
Use a spectrophotometer (6.5) to zero the blank solution of the sample and measure the absorbance at 620 nm. 8.5.4 Draw a calibration curve
Draw a calibration curve with absorbance as the ordinate and amylose content as the abscissa. The amylose content is expressed as a percentage of the dry weight of rice.
8.6 Determination
8.6.1 Color development
Accurately transfer 2.5mL of sample solution into a 50mL colorimetric tube containing 25mL of water, and follow the steps in 8.5.1, adding acetic acid solution first.
8.6.2 Absorbance determination
Use a spectrophotometer to adjust the blank solution of the sample to zero, and measure the absorbance at 620nm. 8.7 Number of determinations
Take two portions of each sample constant solution for parallel determination. 9 Result display
The absorbance is expressed as the percentage of amylose relative to dry basis on the calibration curve. The arithmetic mean of the two determination results is the determination result, and the determination result is retained to one decimal place. 10 Result tolerance
The tolerance of two tests for amylose content above 10.0% shall not exceed 1.0%, and the tolerance of two tests for amylose content below 10.0% shall not exceed 0.5%.
A1 Instruments and equipment
A1.1 Tissue crusher.
A1.2 Sieve: 80 mesh.
A1.3 Centrifuge (4000r/min).
A1.4 Refrigerator.
A1.5 Magnetic stirrer.
GB/T 15683—1995
Appendix A
Preparation method of potato amylose standard (supplement)
A1.6232 calomel electrode or other models with equivalent performance. A1.7213 type platinum electrode or other models with the same performance. A1.80 1.000V millivoltmeter.
A2 Reagents
Except as otherwise noted, all are analytically pure, and water is distilled water. A2.1 Sodium hydroxide (GB629): 0.5mol/L solution. A2.2 Hydrochloric acid (GB622): 1, 1.5 and 2mol/L solutions. A2.3 n-Butanol (HG 3-1012).
A2.4 Isoamyl alcohol (ZBG63001).
A2.5 Potassium iodate standard solution: weigh 0.2140g potassium iodate (GB651, high-grade pure), dissolve it in water, transfer it to a 1000mL volumetric flask, and make up to volume with water, i.e. 1.00×10-4mol/L. A2.6 Potassium iodide solution: Weigh 66.40g potassium iodide (GB1272) and dilute with water to 1000mL, i.e. 0.4mol/L. A3 Preparation method
Weigh 100g fresh potatoes, wash, peel, cut into pieces, put into a tissue masher, add 200mL of water, and crush for 1min. Pass through an 80-mesh sieve, wash the sieve with water, discard the sieve, precipitate, and discard the supernatant. Take the precipitate, add 200mL of water, then add 200mL of 1mol/L sodium hydroxide solution, heat and stir in an 85℃ water bath for 20min until completely dispersed, cool, centrifuge at 4000r/min for 20min, take the supernatant and adjust it to pH 6.5 with 1.5mol/L hydrochloric acid solution, then add 80mL of 1:1 (V/V) butanol-isoamyl alcohol, heat in an 85℃ water bath for 10min, cool to room temperature, move into a refrigerator (2-4℃), let stand for 24h, remove the upper dirt layer, centrifuge at 4000r/min for 20min, discard the supernatant, and the precipitate is crude amylose. Wash the precipitate (crude amylose) with saturated n-butanol aqueous solution, centrifuge at 4000r/min for 15min, transfer the precipitate into 200mL saturated n-butanol aqueous solution, heat and dissolve in a water bath at 85℃ for 10-15min, cool to room temperature, move into a refrigerator (2-4℃), let stand for 24h, discard the upper dirt layer, centrifuge at 4000r/min for 10min, add 200mL saturated n-butanol aqueous solution to the precipitate, heat and dissolve in a water bath at 85℃, and repeat purification 3 times. Finally, wash the precipitate repeatedly with anhydrous ethanol and centrifuge it 3-4 times, disperse it in a plate for 2d, so that the residual ethanol evaporates and the water reaches equilibrium, and the amylose standard is obtained. A4 Determination of standard mass
A4.1 Determination of iodine binding capacity
A4.1.1 Determination
Weigh 0.1000g of standard into a 100mL beaker, add 1.0mL of anhydrous ethanol to moisten the sample, then add 10mL477
GB/T15683—1995
0.5mol/L sodium hydroxide solution in an 85℃ water bath to completely disperse it. After cooling, transfer it to a 100mL volumetric flask, wash the beaker with water several times, transfer the washing solution into the volumetric flask, add water to the scale, and shake well. Pipette 5.0mL (containing 5mg of amylose) dispersion into a 200mL beaker, add 85mL of water, 5.0mL of 1mol/L acetic acid solution and 5.0mL of 0.1mol/L potassium iodide solution. According to the requirements of potentiometric titration, place the beaker on an electromagnetic stirrer, insert a platinum electrode and calomel under the liquid surface, and under electromagnetic stirring, use a 2mL microburette to drop potassium iodate standard solution, 0.1mL (or 0.05mL) each time, read the millivolt after 1min, and calculate the titration endpoint using the second derivative method. A4.1.2 Calculate the iodine binding capacity of
amylose -
where: m-amylose mass, mg;
M-amylose moisture content, %,
× V × 100
m(1 M)
V-1.00×10-3mol/L potassium iodate solution titration volume, mL; 0.7610-each milliliter of 1.00×10-2mol/L potassium iodate is equivalent to the mass of iodine of 0.7610 mg. A4.2 Determination of absorption spectrum of iodine-starch complex Weigh 0.1000g of standard, transfer to a 100mL beaker, add 1.0mL of anhydrous ethanol to wet the sample, then add 9.0mL of 1.0mol/L sodium hydroxide solution, completely disperse in a water bath at 85℃, transfer to a 100mL volumetric flask after cooling, wash the beaker with water several times, transfer all of the solution to the volumetric flask, add water to the mark, and make up to volume. Take 2.0mL of the constant volume solution in a 100mL volumetric flask, transfer 3.0mL of 0.09mol/L sodium hydroxide solution, add 50mL of water to dilute, then add 1.0mL of 1mol/L acetic acid solution and 1.0mL of iodine reagent, add water to make up to 100mL, let stand for 10min, and measure the absorption spectrum at 500-800nm with a spectrophotometer. A4.3 Determination of starch content
Weigh 0.1000g of standard product and add 10mL 0.5mol/L sodium hydroxide solution, heat and disperse in a water bath at 85℃, then add 21.5mL 2mol/L hydrochloric acid solution, reflux and hydrolyze in a boiling water bath for 2h, determine reducing sugar by Fehling's solution method (see GB5513), multiply by 0.9 coefficient to get starch content, and calculate the starch content of the standard product. A4.4 Potato amylose standard product Standard potato amylose standard product must have: a. Iodine binding capacity between 19% and 20%,
b. Amax is 640~650 nm;
Starch content is above 85%.
Appendix B
Preparation of Waxy Rice Amylopectin Standard (Supplement)
B1 Preparation Method
Prepared from waxy rice known to contain at least 99% amylopectin (m/m). The soaked waxy rice is pounded in a tissue pounder until it passes through an 80-100 mesh sieve, and the protein is thoroughly extracted with a reagent (20 g/L sodium dodecyl sulfate solution, with 2 g/L sodium sulfite solution added before use) or an alkali (3 g/L sodium hydroxide solution), washed, and then extracted with methanol in a Soxhlet extractor for 4 h, defatted, and the amylopectin from which the protein and fat have been removed is dispersed in a dish and allowed to stand for 2 days to allow the residual methanol to evaporate and the water content to reach equilibrium. B2 Quality identification of standard products
Determination of absorption spectrum of iodine-starch complex
Take 5.0mL of 5.8 solution (1mg/mL amylopectin), dilute with 50mL water, then add 1.0mL 1mol/L acetic acid solution, 1mL iodine reagent, add water to 100mL, let stand for 10min, and measure the absorption spectrum of 400~~640nm with a spectrophotometer. 478
3 Quality of waxy rice amylopectin standard products
GB/T15683--1995
The waxy rice amylopectin standard product must have a max of 520~530nm, and A℃.c5%620nm is less than 17 at 20℃. Additional remarks:
This standard is proposed by the State Grain Reserves Administration. This standard is under the jurisdiction of the Ministry of Domestic Trade of the People's Republic of China. This standard is drafted by Nanjing University of Economics. The main drafters of this standard are Wang Zhaoci, Yuan Jian and Yang Xiaorong.5. Then add 80 mL of 1:1 (V/V) butanol-isoamyl alcohol, heat in a 85℃ water bath for 10 min, cool to room temperature, move to a refrigerator (2-4℃), let stand for 24 h, remove the upper dirt layer, centrifuge at 4000 r/min for 20 min, discard the supernatant, and the precipitate is crude amylose. Wash the precipitate (crude amylose) with a saturated n-butanol aqueous solution, centrifuge at 4000 r/min for 15 min, transfer the precipitate to 200 mL of saturated n-butanol aqueous solution, heat and dissolve in a 85℃ water bath for 10-15 min, cool to room temperature, move to a refrigerator (2-4℃), let stand for 24 h, discard the upper dirt layer, centrifuge at 4000 r/min for 10 min, add 200 mL of saturated n-butanol aqueous solution to the precipitate, heat and dissolve in a 85C water bath, and repeat the purification 3 times. Finally, the precipitate was repeatedly washed with anhydrous ethanol and centrifuged 3 to 4 times, and then dispersed in a plate for 2 days to allow the residual ethanol to evaporate and the water to reach equilibrium, and the amylose standard was obtained. A4 Standard Quality Determination
A4.1 Iodine Binding Amount Determination
A4.1.1 Determination
Weigh 0.1000g of standard in a 100mL beaker, add 1.0mL anhydrous ethanol to moisten the sample, then add 10mL477
GB/T15683—1995
0.5mol/L sodium hydroxide solution in an 85℃ water bath to completely disperse, cool and transfer to a 100mL volumetric flask, wash the beaker with water several times, transfer the washing liquid to the volumetric flask, add water to the scale, and shake well. Pipette 5.0mL (containing 5mg of amylose) dispersion into a 200mL beaker, add 85mL of water, 5.0mL of 1mol/L acetic acid solution and 5.0mL of 0.1mol/L potassium iodide solution. According to the requirements of potentiometric titration, place the beaker on an electromagnetic stirrer, insert a platinum electrode and calomel under the liquid surface, and under electromagnetic stirring, use a 2mL microburette to drop potassium iodate standard solution, 0.1mL (or 0.05mL) each time, read the millivolt after 1min, and calculate the titration endpoint using the second derivative method. A4.1.2 Calculate the iodine binding capacity of
amylose -
where: m-amylose mass, mg;
M-amylose moisture content, %,
× V × 100
m(1 M)
V-1.00×10-3mol/L potassium iodate solution titration volume, mL; 0.7610-each milliliter of 1.00×10-2mol/L potassium iodate is equivalent to the mass of iodine of 0.7610 mg. A4.2 Determination of absorption spectrum of iodine-starch complex Weigh 0.1000g of standard, transfer to a 100mL beaker, add 1.0mL of anhydrous ethanol to wet the sample, then add 9.0mL of 1.0mol/L sodium hydroxide solution, completely disperse in a water bath at 85℃, transfer to a 100mL volumetric flask after cooling, wash the beaker with water several times, transfer all of the solution to the volumetric flask, add water to the mark, and make up to volume. Take 2.0mL of the constant volume solution in a 100mL volumetric flask, transfer 3.0mL of 0.09mol/L sodium hydroxide solution, add 50mL of water to dilute, then add 1.0mL of 1mol/L acetic acid solution and 1.0mL of iodine reagent, add water to make up to 100mL, let stand for 10min, and measure the absorption spectrum at 500-800nm with a spectrophotometer. A4.3 Determination of starch content
Weigh 0.1000g of standard product and add 10mL 0.5mol/L sodium hydroxide solution, heat and disperse in a water bath at 85℃, then add 21.5mL 2mol/L hydrochloric acid solution, reflux and hydrolyze in a boiling water bath for 2h, determine reducing sugar by Fehling's solution method (see GB5513), multiply by 0.9 coefficient to get starch content, and calculate the starch content of the standard product. A4.4 Potato amylose standard product Standard potato amylose standard product must have: a. Iodine binding capacity between 19% and 20%,
b. Amax is 640~650 nm;
Starch content is above 85%.
Appendix B
Preparation of Waxy Rice Amylopectin Standard (Supplement)
B1 Preparation Method
Prepared from waxy rice known to contain at least 99% amylopectin (m/m). The soaked waxy rice is pounded in a tissue pounder until it passes through an 80-100 mesh sieve, and the protein is thoroughly extracted with a reagent (20 g/L sodium dodecyl sulfate solution, 2 g/L sodium sulfite solution is added before use) or an alkali (3 g/L sodium hydroxide solution), washed, and then extracted with methanol in a Soxhlet extractor for 4 h, defatted, and the amylopectin from which the protein and fat have been removed is dispersed in a dish and allowed to stand for 2 days to allow the residual methanol to evaporate and the water content to reach equilibrium. B2 Quality identification of standard products
Determination of absorption spectrum of iodine-starch complex
Take 5.0mL of 5.8 solution (1mg/mL amylopectin), dilute with 50mL water, then add 1.0mL 1mol/L acetic acid solution, 1mL iodine reagent, add water to 100mL, let stand for 10min, and measure the absorption spectrum of 400~~640nm with a spectrophotometer. 478
3 Quality of waxy rice amylopectin standard products
GB/T15683--1995
The waxy rice amylopectin standard product must have a max of 520~530nm, and A℃.c5%620nm is less than 17 at 20℃. Additional remarks:
This standard is proposed by the State Grain Reserves Administration. This standard is under the jurisdiction of the Ministry of Domestic Trade of the People's Republic of China. This standard is drafted by Nanjing University of Economics. The main drafters of this standard are Wang Zhaoci, Yuan Jian and Yang Xiaorong.5. Then add 80 mL of 1:1 (V/V) butanol-isoamyl alcohol, heat in a 85℃ water bath for 10 min, cool to room temperature, move to a refrigerator (2-4℃), let stand for 24 h, remove the upper dirt layer, centrifuge at 4000 r/min for 20 min, discard the supernatant, and the precipitate is crude amylose. Wash the precipitate (crude amylose) with a saturated n-butanol aqueous solution, centrifuge at 4000 r/min for 15 min, transfer the precipitate to 200 mL of saturated n-butanol aqueous solution, heat and dissolve in a 85℃ water bath for 10-15 min, cool to room temperature, move to a refrigerator (2-4℃), let stand for 24 h, discard the upper dirt layer, centrifuge at 4000 r/min for 10 min, add 200 mL of saturated n-butanol aqueous solution to the precipitate, heat and dissolve in a 85C water bath, and repeat the purification 3 times. Finally, the precipitate was repeatedly washed with anhydrous ethanol and centrifuged 3 to 4 times, and then dispersed in a plate for 2 days to allow the residual ethanol to evaporate and the water to reach equilibrium, and the amylose standard was obtained. A4 Standard Quality Determination
A4.1 Iodine Binding Amount Determination
A4.1.1 Determination
Weigh 0.1000g of standard in a 100mL beaker, add 1.0mL anhydrous ethanol to moisten the sample, then add 10mL477
GB/T15683—1995
0.5mol/L sodium hydroxide solution in an 85℃ water bath to completely disperse, cool and transfer to a 100mL volumetric flask, wash the beaker with water several times, transfer the washing liquid to the volumetric flask, add water to the scale, and shake well. Pipette 5.0mL (containing 5mg of amylose) dispersion into a 200mL beaker, add 85mL of water, 5.0mL of 1mol/L acetic acid solution and 5.0mL of 0.1mol/L potassium iodide solution. According to the requirements of potentiometric titration, place the beaker on an electromagnetic stirrer, insert a platinum electrode and calomel under the liquid surface, and under electromagnetic stirring, use a 2mL microburette to drop potassium iodate standard solution, 0.1mL (or 0.05mL) each time, read the millivolt after 1min, and calculate the titration endpoint using the second derivative method. A4.1.2 Calculate the iodine binding capacity of
amylose -
where: m-amylose mass, mg;
M-amylose moisture content, %,
× V × 100
m(1 M)
V-1.00×10-3mol/L potassium iodate solution titration volume, mL; 0.7610-each milliliter of 1.00×10-2mol/L potassium iodate is equivalent to the mass of iodine of 0.7610 mg. A4.2 Determination of absorption spectrum of iodine-starch complex Weigh 0.1000g of standard, transfer to a 100mL beaker, add 1.0mL of anhydrous ethanol to wet the sample, then add 9.0mL of 1.0mol/L sodium hydroxide solution, completely disperse in a water bath at 85℃, transfer to a 100mL volumetric flask after cooling, wash the beaker with water several times, transfer all of the solution to the volumetric flask, add water to the mark, and make up to volume. Take 2.0mL of the constant volume solution in a 100mL volumetric flask, transfer 3.0mL of 0.09mol/L sodium hydroxide solution, add 50mL of water to dilute, then add 1.0mL of 1mol/L acetic acid solution and 1.0mL of iodine reagent, add water to make up to 100mL, let stand for 10min, and measure the absorption spectrum at 500-800nm with a spectrophotometer. A4.3 Determination of starch content
Weigh 0.1000g of standard product and add 10mL 0.5mol/L sodium hydroxide solution, heat and disperse in a water bath at 85℃, then add 21.5mL 2mol/L hydrochloric acid solution, reflux and hydrolyze in a boiling water bath for 2h, determine reducing sugar by Fehling's solution method (see GB5513), multiply by 0.9 coefficient to get starch content, and calculate the starch content of the standard product. A4.4 Potato amylose standard product Standard potato amylose standard product must have: a. Iodine binding capacity between 19% and 20%,
b. Amax is 640~650 nm;
Starch content is above 85%.
Appendix B
Preparation of Waxy Rice Amylopectin Standard (Supplement)
B1 Preparation Method
Prepared from waxy rice known to contain at least 99% amylopectin (m/m). The soaked waxy rice is pounded in a tissue pounder until it passes through an 80-100 mesh sieve, and the protein is thoroughly extracted with a reagent (20 g/L sodium dodecyl sulfate solution, with 2 g/L sodium sulfite solution added before use) or an alkali (3 g/L sodium hydroxide solution), washed, and then extracted with methanol in a Soxhlet extractor for 4 h, defatted, and the amylopectin from which the protein and fat have been removed is dispersed in a dish and allowed to stand for 2 days to allow the residual methanol to evaporate and the water content to reach equilibrium. B2 Quality identification of standard products
Determination of absorption spectrum of iodine-starch complex
Take 5.0mL of 5.8 solution (1mg/mL amylopectin), dilute with 50mL water, then add 1.0mL 1mol/L acetic acid solution, 1mL iodine reagent, add water to 100mL, let stand for 10min, and measure the absorption spectrum of 400~~640nm with a spectrophotometer. 478
3 Quality of waxy rice amylopectin standard products
GB/T15683--1995
The waxy rice amylopectin standard product must have a max of 520~530nm, and A℃.c5%620nm is less than 17 at 20℃. Additional remarks:
This standard is proposed by the State Grain Reserves Administration. This standard is under the jurisdiction of the Ministry of Domestic Trade of the People's Republic of China. This standard is drafted by Nanjing University of Economics. The main drafters of this standard are Wang Zhaoci, Yuan Jian and Yang Xiaorong.9 coefficient, then the starch content is obtained, and the starch content of the standard is calculated. A4.4 Potato amylose standard The standard potato amylose standard must have: a. Iodine binding capacity between 19% and 20%,
b. Amax is 640~650 nm;
Starch content is above 85%.
Appendix B
Preparation of waxy rice amylopectin standard (supplement)
B1 Preparation method
Prepared from waxy rice known to contain at least 99% amylopectin (m/m). The waxy rice was pounded in a tissue pounder until it passed through an 80-100 mesh sieve, and the protein was thoroughly extracted with a reagent (20 g/L sodium dodecyl sulfate solution, 2 g/L sodium sulfite solution was added before use) or an alkali (3 g/L sodium hydroxide solution), washed, and then extracted with methanol in a Soxhlet extractor for 4 h, defatted, and the amylopectin from which the protein and fat were removed was dispersed in a dish and allowed to stand for 2 days to allow the residual methanol to evaporate and the water content to reach equilibrium. B2 Standard Quality Identification
Iodine-starch complex absorption spectrum determinationwww.bzxz.net
Take 5.0 mL of 5.8 solution (1 mg/mL amylopectin), dilute it with 50 mL of water, then add 1.0 mL of 1 mol/L acetic acid solution, 1 mL of iodine reagent, add water to 100 mL, let it stand for 10 min, and measure the absorption spectrum of 400~~640 nm with a spectrophotometer. 478
3 Quality of Waxy Rice Amylopectin Standard Product
GB/T15683--1995
Waxy Rice Amylopectin Standard Product must have a maximum of 520~530nm, and an A℃.c5% of 620nm at 20℃ is less than 17. Additional Notes:
This standard was proposed by the State Grain Reserves Administration. This standard is under the jurisdiction of the Ministry of Domestic Trade of the People's Republic of China. This standard was drafted by Nanjing University of Economics. The main drafters of this standard are Wang Zhaoci, Yuan Jian, and Yang Xiaorong. 4799 coefficient, then the starch content is obtained, and the starch content of the standard is calculated. A4.4 Potato amylose standard The standard potato amylose standard must have: a. Iodine binding capacity between 19% and 20%,
b. Amax is 640~650 nm;
Starch content is above 85%.
Appendix B
Preparation of waxy rice amylopectin standard (supplement)
B1 Preparation method
Prepared from waxy rice known to contain at least 99% amylopectin (m/m). The waxy rice was pounded in a tissue pounder until it passed through an 80-100 mesh sieve, and the protein was thoroughly extracted with a reagent (20 g/L sodium dodecyl sulfate solution, 2 g/L sodium sulfite solution was added before use) or an alkali (3 g/L sodium hydroxide solution), washed, and then extracted with methanol in a Soxhlet extractor for 4 h, defatted, and the amylopectin from which the protein and fat were removed was dispersed in a dish and allowed to stand for 2 days to allow the residual methanol to evaporate and the water content to reach equilibrium. B2 Standard Quality Identification
Iodine-starch complex absorption spectrum determination
Take 5.0 mL of 5.8 solution (1 mg/mL amylopectin), dilute it with 50 mL of water, then add 1.0 mL of 1 mol/L acetic acid solution, 1 mL of iodine reagent, add water to 100 mL, let it stand for 10 min, and measure the absorption spectrum of 400~~640 nm with a spectrophotometer. 478
3 Quality of Waxy Rice Amylopectin Standard Product
GB/T15683--1995
Waxy Rice Amylopectin Standard Product must have a maximum of 520~530nm, and an A℃.c5% of 620nm at 20℃ is less than 17. Additional Notes:
This standard was proposed by the State Grain Reserves Administration. This standard is under the jurisdiction of the Ministry of Domestic Trade of the People's Republic of China. This standard was drafted by Nanjing University of Economics. The main drafters of this standard are Wang Zhaoci, Yuan Jian, and Yang Xiaorong. 479
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