GB/T 5492-1985 Grain and oilseed inspection - Color, odor and taste identification method

This standard applies to the identification of the color, smell and taste of commercial grains and oils. GB/T 5492-1985 Method for identification of color, smell and taste of grains and oils GB/T5492-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for identification of colour, odour and taste of grain and oilseeds Inspection of grain and oilseedsMethods for identification of colour, odour and tasteThis standard applies to the identification of colour, odour and taste of commercial grain and oilseeds. 1
Identification of colour
GB/T5492-85
During identification, place the sample under scattered light and visually identify whether the colour and gloss of all samples are normal. 2 Identification of odour
2.1 Take a small amount of sample, blow air on the sample, and immediately smell to determine whether the odour is normal. 2.2 Place the sample in a sealed container, keep it warm in a cup of warm water at 60-70℃ for several minutes, take it out, open the cover film to determine whether the odour is normal.
3 Identification of taste
Finished grains should be cooked as mature food and tasted to determine whether their taste is normal. 4 Result expression
Normal grains and oilseeds have inherent colour, gloss, odour and taste. The identification result is expressed as "normal" or "abnormal". Abnormal results should be explained. Appendix A
Test for fresh and old grains
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A.1 Guaiacol reaction method
A.1.1 Take 50100 grains of grain sample and place them in a test tube. Add 2ml of 1% guaiacol solution (the original solution is diluted 100 times with water) and vibrate. Then add 13 drops of 3% hydrogen peroxide solution. After vibrating, let it stand for a while. The grains and the solution will show color. At the same time, make a control test for comparison. The darker the color, the stronger the activity of the enzyme, indicating that the grain is relatively fresh. A.1.2 Take about 5g of rice and place it in a test tube, add 10ml of 1% guaiacol solution, shake it about 20 times, transfer the guaiacol solution
to another test tube, let it stand, add 3 drops of 1% hydrogen peroxide solution, and observe the color development of the guaiacol solution while it is standing. If it is new rice, after 1 to 3 minutes, the turbid guaiacol solution will start to turn dark reddish brown from the top; old rice will not show any color at all. If new and old rice are mixed, the new rice has a higher proportion, the color reaction is fast, and it is dark reddish brown; the old rice has a higher proportion: the color reaction is slow, and it is light reddish brown. A.2 Guaiacol and p-phenylenediamine combined method
Take 50 to 100 test samples and place them in a test tube, add 4ml of 1% guaiacol solution, shake it and let it stand for about 2 minutes. Then
add 3-4 drops of 3% hydrogen peroxide solution, vibrate, add 3ml of 2% p-phenylenediamine solution, vibrate, let stand and then pour out the solution in the test tube, rinse the sample with water for observation. For new grain, the enzyme activity is strong and the color is deep; for old grain, the enzyme activity is weak and the color is slow and light.
A.3 Acidity indicator method
A.3.1 Preparation of stock solution: Take 0.1g of methyl red and 0.3g of bromothymol blue and dissolve them in 150ml of ethanol, and dilute with water to 200ml as the stock solution.
A.3.2 Determine the freshness and staleness of all samples: Mix the stock solution with water at a ratio of 1:50 as the working solution. Take 5g of the sample and add 10ml of the working solution, vibrate and observe the color of the solution. The newer the rice grains, the greener they are, and the oxidized ones change from yellow to orange. A.3.3 Determine the mixing ratio of new and old rice: Mix the stock solution with water at a ratio of 1:4, titrate with alkali solution, adjust from red to yellow (residual yellow turns to green), as the working solution, take 20 to 100 test pieces, add them into 10 ml of the working solution, vibrate, and immediately rinse with water after the test pieces are colored, and determine the freshness based on the coloring. Green → yellow → orange with the oxidation. Note: ① The mixing ratio of indicators in A.3.2 and A.3.3 and the dilution ratio of the stock solution are not absolute and can be changed as appropriate based on the oxidation degree of the test piece.
The first method can be used for raw grains. Several methods are best used for rice. ③
This data is extracted from the standard measurement method compiled by the Food and Agriculture Agency of Japan in May 1949. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China. This standard was 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 Yanxia, ​​and Lv Guifen. Issued by the National Bureau of Standards on November 2, 1985
Implemented on July 1, 1986
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