GB/T 5494-1985 Inspection method for impurities and imperfect grains in grain and oilseeds
Some standard content:
National Standard of the People's Republic of China
Inspection of grain and oilseeds GB/T5494-85
Methods for determination of foreign matter and unsound kernels This standard applies to the inspection of foreign matter and unsound kernels in commercial grain and oilseeds. Impurity inspection
1.1 Instruments and appliances
1.1.1 Balance: sensitivity 0.01g, 0.1g; 1.1.2 Grain screening;
1.1.3 Electric screener;
1.1.4 Sample divider and sample dividing plate;
1.1.5 Analysis plate, tweezers, etc.
1.2 Samples
The samples for testing impurities are divided into large samples and small samples: large samples are used to test large sample impurities, including large impurities and the screened materials of the absolute sieve layer; small samples are a small amount of samples separated from the samples that have been tested for large sample impurities, to test the impurities similar to the size of grains. The amount of samples used for testing impurities is shown in the following table: Specimen dosage table for testing impurities
Names of grains and oilseeds
Small grains: such as chestnuts, sesame seeds, rapeseed, etc.
Medium grains: such as rice, wheat, sorghum, adzuki beans, cotton seeds, etc.Large grains: such as soybeans, corn, peas, sunflower seeds, small-grain broad beans, etc.Extra-large grains: such as peanuts, kernels, sesame seeds, tung seeds, tea seeds, Xanthoceras sorbifolia, large-grain broad beans, etc.
Others: sweet potato slices, rice with shelled barnyard millet and rice grains1.3 Screening
1 Large Sample weight (g)
5001000
Small sample weight (g)
1.3.1 Electric screener method: Set the sieve layer as specified in the quality standard (large-hole sieve on top, small-hole sieve on bottom, set the sieve bottom), weigh the sample as specified and put it on the sieve, cover the sieve cover, put it on the electric screener, connect the power supply, turn on the switch, the sieve will automatically sieve left and right for 1 minute each (110-120 revolutions per minute), stand still for a while after sieving, and pour the sieve and undersieve into the analysis plate respectively. The particles stuck in the middle of the sieve hole belong to the sieve. 1.3.2 Hand sieve method: Set the sieve layer according to the above method, pour the sample, and cover the sieve cover. Then put the sieve on a glass plate or a smooth table, and use both hands to sieve in clockwise and counterclockwise directions at a speed of 110-120 times per minute for 1 minute each. The range of sieving movement is controlled within the range of 8-10cm expansion of the sieve diameter. The operation after sieving is the same as above. 1.4 Large sample impurity test
1.4.1 Operation method: From the average sample, weigh the sample (W) according to the provisions of 1.2, and screen it twice according to the screening method (four times for extra-large grains and oilseeds), then wipe out the large impurities on the sieve and weigh them together (W1). (Large impurities of wheat are removed on the 4.5mm sieve).
1.4.2 Result calculation
The large sample impurity content is calculated according to formula (1):
Large sample impurity (%)=
W—large sample weight, g.
The allowable difference between the two test results shall not exceed 0.3%. The average is the test result. The test result is taken to the first decimal place.
1.5 Small sample impurity test
1.5.1 Operation method: From the sample that has been tested for large sample impurities, weigh the sample (W2) according to the amount specified in 1.2, pour it into the analysis plate, remove the impurities according to the quality standard, and weigh it (W3). 1.5.2 Result calculation
The small sample impurity content is calculated according to formula (2):
Small sample impurity (%) = (100-M) ×
Where: W3——small sample impurity weight, g; W2——small sample weight, g;
M large sample impurity percentage, %.
The allowable difference between the two test results shall not exceed 0.3%. The average is the test result. The test result is rounded to the first decimal place.
1.6 Mineral test
1.6.1 Operation method: For mineral indicators specified in the quality standard (excluding rice), wipe out the minerals from the impurities in the small sample and weigh them (W4).
1.6.2 Result calculation
Mineral content is calculated according to formula (3):
Mineral (%)=(100-M)×
Mineral weight, g:bzxz.net
W4-
W2——small sample weight, g;
M large sample impurity percentage, %.
The allowable difference between the two test results shall not exceed 0.1%. The average is the test result. The test result is rounded to the second decimal place.
1.7 Calculation of total impurities
The total impurities of general grains and oilseeds are calculated according to formula (4): Total impurities (%) = M + N.
Where: M—percentage of impurities in a large sample, %;...4
N—percentage of impurities in a small sample, %.
The calculation result is rounded to the first decimal place.
1.8 Inspection of rice impurities
1.8.1 Inspection of powdered sugar
1.8.1.1 Operation method: Take a sample of about 200g (W) from the average sample and put it into a 1.0mm diameter round hole sieve twice. Screen according to the screening method specified in 1.3, pour out the sample, and tap the sieve to make the bran powder fall to the bottom of the sieve. After all the samples are screened, brush off the bran powder left on the sieve layer and weigh them together (W1). 1.8.1.2 Calculation of results
The bran powder content is calculated according to formula (5):
Bran powder (%)=
W—sample weight, g.
X10.....)
The allowable difference between the two test results shall not exceed 0.04%. The average is the test result. The test result is rounded to the second decimal place.
1.8.2 Mineral test
1.8.2.1 Operation method: Extract minerals from the sample tested for bran powder and weigh them (W2). 1.8.2.2 Calculation of results
Mineral content is calculated according to formula (6):
Minerals (%)
W—sample weight, g.
X10.....)
The allowable difference between the two test results shall not exceed 0.04%. The average is the test result. The test result is rounded to the second decimal place.
1.8.2 Mineral test
1.8.2.1 Operation method: Extract minerals from the sample tested for bran powder and weigh them (W2). 1.8.2.2 Calculation of results
Mineral content is calculated according to formula (6):
Minerals (%)
W—sample weight, g.
The allowable difference between the two test results is not more than 0.005%. The average is the test result. The test result is rounded to the second decimal place.
1.8.3 Test for other impurities
1.8.3.1 Operation method: From the sample that has been tested for bran powder and minerals, separate the rice grains, barnyard grains and other impurities and weigh them together (W3).
1.8.3.2 Result calculation
The content of other impurities is calculated according to formula (7):
Other impurities (%) =:
Where: W3—weight of rice grains, barnyard grains and other impurities, g; W—weight of sample, g.
The allowable difference between the two test results is not more than 0.04%. The average is the test result. The test result is rounded to the second decimal place.
1.8.4 Inspection of hulled barnyard grains and rice grains
Take 500g of the sample from the average sample, wipe out the hulled barnyard grains and rice grains, and calculate the content respectively. The number of grains multiplied by 2 is the test result, expressed as "grains/kg". The allowable difference between the two test results is no more than 3 grains/kg for hulled barnyard grains and no more than 2 grains/kg for rice grains. The average is the test result. If the average is less than 1 grain, it is calculated as 1 grain. 1.8.5 Calculation of total amount of rice impurities
The total amount of rice impurities is calculated according to formula (8):
Total amount of rice impurities (%) = A+B+C
- bran powder percentage;
Where: A
B——mineral percentage;
C——other impurity percentage.
The calculation result is rounded to the second decimal place.
2 Imperfect grain inspection
2.1 Operation method: While inspecting the impurities in the small sample, remove the imperfect grains according to the quality standard and weigh them (W1). 2.2 Result calculation
The imperfect grain content is calculated according to formula (9):
Imperfect grain (%)=(100-M)×
Where: W1——imperfect grain weight, g; w——sample weight, g;
M—large sample impurity percentage, %.
The allowable difference between the two test results: large grains and extra-large grains shall not exceed 1.0%; small and medium grains shall not exceed 0.5%. The average is the test result, and the test result is rounded to the first decimal place. 3 Calculation of pure grain (quality) rate
3.1 Calculation of pure grain (quality) rate of net grain
The pure grain (quality) rate of net grain is calculated according to formula (10): W-W1-2
Pure grain (quality) (%)=
W1——weight of imperfect grain, g; weight of sample, g.
3.2 Calculation of the pure grain (quality) rate of raw grain
The pure grain (quality) rate of raw grain is calculated according to formula (11): W
W-(W2+W1-2)
Pure grain (quality) (%)=
W1--weight of imperfect grain, g; W2--weight of impurities, g;
W--weight of sample, g.
The calculation result is rounded to the first decimal place.
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. X100
The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia and Lv Guifen. ..(11)
Published by the National Bureau of Standards on November 2, 1985
Implemented on July 1, 1986
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