Determination of protein and starch content in rice seeds.

:
rice is one of the important food crops, and its quality is a problem worthy of people's attention. A high-yielding rice variety is often not popular with the public because of poor taste or lack of nutrition. Therefore, while ensuring high yield, the quality of rice should be improved. This experiment will determine the quality of rice several important
bio
and biological indicators, for rice breeding to provide a theoretical basis.
I. Rice
protein
content determination - Kaomas Lianglan G-250 method
I, principle
Kaomas Liang G-250 is a dye, in the free state is red, at 465nm wavelength has the maximum light absorption. It binds to protein stability, binds to proteins and turns cyan, has maximum absorption at 595nm, within a certain protein concentration range (0 to 1000 μg/ml), protein-pigment bindings at 595nm wavelengths of light absorption is directly related to protein content, so it can be used for quantitative determination of proteins.
the method is rapid, and the binding reaction between the protein and the Coomas Lianglan G-250 can be balanced in 2 minutes. The binding remains stable at room temperature for 1 hour, the reaction is very sensitive, the protein content of microgram level can be measured, is a new development of a more ideal protein quantification method.
II, experimental materials, instruments and
reagents1. Instrument:
721 hydrometer
centrifuge
50ml capacity bottle 10ml scale
tet tube
research tube pipe pipe
2. Reagents:
(1) bovine
serum
albumin (1000 μg/ml): 100.00 mg bovine serum albumin, dissolved in 100 ml distilled water, with a standard protein solution.
(2) Coomas Lianglan G-250 solution: said to take 100 ml Ofimas Lianglan G-250, dissolved in 50 ml 90% ethanol, add 85% (W/V) phosphoric acid 100 ml, and finally with distilled water to 1000 ml,
filtration
, can be placed at room temperature for 1 month.
(3) 0.1mol/LnaOH: 4g hydroxide, dissolved with distilled water, and fixed to 1000ml.
3. Materials: Rice powder
, experimental method
1. Production of standard curves:
6 10 ml scale test tubes, numbered, according to the table data preparation of bovine serum albumin standard solution. Accurately absorb the above-mentioned tube solution 0.1 ml, corresponding to put in the other 6 10 ml scale test tube, add 5 ml Kaomas Lianglan G-250 solution, gai plug, the test tube solution to reverse mixing, after 2 minutes, with 10mm light diameter color cup at 595nm wavelength. The standard curve is made with the light density value as the ordinate and the protein concentration value as the horizontal coordinate. 2. Protein extraction in samples:
(1) accurately weighing 0.5 grams of rice flour, put in the research, add 2 ml 0.1mol/L NaOH, grind into a homogenous slurry, transfer to 10 ml centrifuge tube Medium, with 6 ml 0.1mol / L NaOH three times washing research, lotion into a 10 ml centrifuge tube, stirring with a stick, placed for 30 minutes, the placement process intermittently stirred several times. 3500rpm centrifugation 15 minutes, the liquid into a 50 ml capacity bottle, with distilled water to the scale, shake well, alkali soluble protein.
(2) the above precipitation is repeatedly extracted with 70% ethanol, the operating steps are the same, the alcohol-soluble protein.
3. Determination:
0.1 ml of absorbent extract, put in 10 ml plug-scale test tube, add 5 ml of Coomas Lianglan G-250 reagent, mix well, place for 2 minutes, with 10mm light The diameter color cup is colored at a wavelength of 595nm (the color blank is mixed with 5 ml of Coomas Lianglan G-250 reagent instead of the extract with 0.1 ml distilled water), and the OD value is recorded. The corresponding protein concentration (C) was then found on the standard curve based on the OD595nm measured.
4, the result calculation:
5, note:
(1) Because this method is very sensitive, therefore, the utensils used must be cleaned, sampling must be accurate, otherwise it will cause a large error.
(2) when the distilled water to be slowly added along the pipe wall, so as not to produce a large number of bubbles, resulting in inaccurate positioning, the experiment will also appear errors.
(3) grain seed protein is mainly gluten and alcohol-soluble protein, therefore, rice powder protein content should be alkali-soluble gluten and alcohol-soluble protein content.
II. The spinlight method determines the total starch of rice
I, principle
starch because it contains asymmetric carbon atoms, so it has a spinlight. Under
heating
conditions, starch can be dispersed in a solution of thin hydrochloric acid, with phosphorus tungsten acid precipitation protein and other spin-light substances, the solution will be fixed to a certain volume. The rotor polarization angle of the starch solution was determined by using the rotary photometric instrument. Depending on the contrasting luspance of different crop starches, .