GB 5514-1985 Inspection of grains and oilseeds - Determination of starch

This standard is applicable to the determination of starch content in commercial grains and oilseeds. GB 5514-1985 Grain and oilseed inspection method for determination of starch GB5514-1985 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Inspection of grain and oilseedsMethods for determination of starch
Inspection of grain and oilseedsMethods for determination of starch This standard is applicable to the determination of starch content in commercial grain and oilseeds. 1 Instruments and appliances
1.1 Gooch crucible: 25ml,
1.2 Filter flask: 500ml,
1.3 Vacuum pump or water pump,bzxz.net
1.4 Burette: 25ml,
Conical flask: 100ml, 250ml.500mls
Pipette: 20ml,
1.7 Volumetric flask: 100ml, 250ml, 500ml,1.8
Reflux condenser,
1.9 Electric furnace,
Flask: 150ml,
Funnel, 6cm,
Mortar, thermometer, microscope, etc.
2 Reagents
UDC (633.1+633.85)
.001.4
GB5514—85
2.10.5% amylase solution or malt juice: Soak barley grains in water for 12 hours, spread them in a porcelain plate with a thickness of about 1 cm, and let them germinate for several days. When the sprouts are about 1 cm long, take 50g of the sprouted grains, grind them, add 400ml of water, soak them at room temperature for 3h, filter and set aside (add a few drops of chloroform or toluene when storing to prevent it from growing)
2.2 Iodine solution: weigh 3.6g of potassium iodide, dissolve it in 20ml of water, add 1.3g of iodine, add water to 100ml after dissolution, 2.30.1N potassium permanganate standard solution,
2.41N sodium hydroxide solution: take 4g of sodium hydroxide and dissolve it in water to 100ml, 2.5 Ferrous sulfate solution: take 50g of ferrous sulfate, add 200ml of water and dissolve it, then slowly add 100ml of sulfuric acid, add water to 1000ml after cooling, 2.63N hydrochloric acid: take 25ml of hydrochloric acid and add water to 100ml, 2.76N hydrochloric acid: take 10 0ml, add water to 200ml, 2.820% sodium hydroxide solution,
2.9 Methyl red indicator: 0.1% methyl red ethanol solution, 2.10 Fehling's solution:
2.10.1 Alkaline copper tartrate solution A: Take 34.69g of copper sulfate crystals, add appropriate amount of water to dissolve, add 0.5ml of sulfuric acid, then add water to 500ml, filter with refined asbestos
2.10.2 Alkaline copper tartrate solution B: Take 173g of potassium sodium tartrate and 50g of sodium hydroxide, add appropriate amount of water to dissolve, dilute to 500ml, filter with refined asbestos, and store in a glass bottle with a rubber stopper. National Bureau of Standards 1985-11-02 Issued
1986-07-01 Implementation
GB 5514--85
2.11 Refined asbestos: Soak the asbestos in 3N hydrochloric acid for 2-3 days, then wash with water. Then add 10% sodium hydroxide solution and soak for 2-3 days, pour off the solution, soak in hot alkaline copper tartrate solution for several hours, then wash with water. Then soak in 3N hydrochloric acid for several hours, then wash with water until it is no longer acidic, so that it becomes fine soft fibers, soak in water and store in a glass bottle for filling Gushi. 3 Operation method
Weigh 2-5g of the sample and place it in a funnel with folded filter paper. First, wash away the fat with 50ml of ether for 5 times, then wash away the soluble sugars with 85% ethanol, transfer the residue into a 250ml beaker, wash the residue on the filter paper into the beaker with about 50ml of water several times, heat it in a boiling water bath for 15min to gelatinize the starch, cool it to 60℃, add 20ml of amylase solution (or malt juice), maintain 55-60℃ for hydrolysis for 1h, and stir frequently. Then take 1 drop and add 1 drop of iodine solution. If it turns blue, heat it again for gelatinization, and add 20ml of amylase solution (or malt juice) to hydrolyze until the iodine solution is no longer blue. Heat it to boiling, cool it and transfer it to a 250ml volumetric flask, add water to the scale, and mix it. Filter, discard the initial filtrate, take 50ml and inject it into a 100ml volumetric flask, add 5ml of 6N hydrochloric acid, heat in a 68~70℃ water bath for 15min, add 2 drops of methyl red indicator solution after cooling, neutralize with 20% sodium hydroxide solution, add water to the scale, mix well, and use it to determine reducing sugar. At the same time, take 50ml of water and the same amount of amylase solution (or malt juice) for reagent blank test. 4 Calculation of results
Starch dry basis content is calculated according to the following formula: 5000×0.9(A'-B)
Starch (dry basis %) =
WV(100-M)
Where: A—weight of reducing sugar (in glucose) measured after conversion, mg, B—reagent blank equivalent to the weight of reducing sugar (in glucose), mgsV—volume of reducing sugar measured after dilution to 100ml after conversion, ml, W_—sample weight, gs
M—sample moisture percentage, %
0.9—factor for reducing sugar (in glucose) converted to starch. The allowable difference between the two test results shall not exceed 1% of the average value, and the average value shall be taken as the test result. The test result shall be taken to the first decimal place.
Note, ① Homemade amylase: Take germinated wheat grains, dry them at 25-35℃, and grind them into powder. Add 200ml of 20% ethanol to every 100g of powder, soak for 24h, squeeze and filter with fine cloth, and add double the amount of ethanol for precipitation. After the precipitate is filtered through a Buchner funnel, it is placed in a mortar and ground with ethanol, filtered again, and the precipitate is washed with ethanol and ether, and finally dried in a sulfuric acid dryer for use. ② When the sample contains very little fat, it is not necessary to wash with ether. ③ Before using amylase, a small amount of starch paste solution with a known content can be used, and a certain amount of amylase solution can be added, heated in a water bath at 55-60℃ for 1h, and observed with iodine solution to see whether the blue color decreases or disappears after hydrolysis, so as to determine the activity of the enzyme and the amount required for hydrolysis. The general amylase activity is 1.:25, 1:50 and 1:100.
Additional remarks:
This standard is proposed by the Ministry of Commerce of the People's Republic of China. This standard is drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanlin and Lv Guifen. 269
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