The rice yield detector is a core equipment used to evaluate the quality of rice processing. Its measurement indicators and methods revolve around the quality conversion efficiency of rice after husking and whitening, as follows:
1、 Core measurement indicators
Rice yield rate
Definition: The percentage of polished rice weight to the weight of the rice sample reflects the actual efficiency of rice processing into rice.
Standard reference:
The yield rate of first-class rice should not be less than 70% (GB1354-2014 "Quality Standards for Rice");
Second class products shall not be less than 67%, and third class products shall not be less than 64%.
Technical Requirements:
The detector needs to shell the rice through a rice hulling rubber roller, and the uncoating rate after one hulling is less than 0.5% for japonica rice and less than 1.5% for indica rice.
Rough whitening rate
Definition: The percentage of polished rice weight to the weight of brown rice after milling reflects the conversion ability of polished rice in the milling process.
Technical Requirements:
The rice milling processing time can be adjusted (such as 35 seconds), the processing capacity is 20-50g/time, and the repeatability range of the whole rice rate is ≤ 1.5%.
Other auxiliary indicators
Total impurities: The content of impurities (such as stones and sand particles) in rice.
Imperfect rate: The proportion of immature or damaged rice grains.
Yellow grain rice rate: The proportion of yellow grains caused by heat or mold.
Off grain brown rice rate: the proportion of partially shelled brown rice.
2、 Measurement method
Sample preparation
Sampling: Take samples from representative rice grains, with a laboratory sample size of no less than 2kg.
Sample splitting: Use a sampler to mix the sample evenly and reduce it to the required amount for testing (such as 200g).
Preprocessing: Pick out impurities and out of grain brown rice to ensure sample purity; Adjust the moisture content of rice to a suitable range (13.5% -16.5% for japonica rice).
Hulling of rice husks
Equipment adjustment:
The diameter of the rice husking rubber roller is usually 99-100mm, and the motor power is 550W;
The air volume can be adjusted, with a processing capacity of 6kg/h for japonica rice or 4kg/h for indica rice.
Operation steps:
Add clean rice to the hulling chamber and start the instrument for hulling;
Collect brown rice and remove husk debris.
Refined rice milling
Equipment adjustment:
The height of the rice milling room can be adjusted, and the sample weight is about 20g (60 seconds for japonica rice and 40 seconds for indica rice);
The bran hole diameter is 1.5mm, and the built-in vacuum fan has a power of 400W.
Operation steps:
Add brown rice to the rice milling chamber and start the instrument to whiten it;
Remove rice bran to obtain polished rice.
Screening and weighing
Screening: Place the polished rice into a 2.5mm diameter circular hole sieve, and rotate the electric filter forward and backward for 1 minute each to screen for broken rice and impurities.
Weighing:
Weigh the sieved material (intact polished rice) to the nearest 0.01g;
Weigh the mass of the screened material (broken rice and impurities).
Data calculation and recording
Calculate indicators such as rice yield, roughness, and whiteness based on formulas;
Record test conditions (such as temperature, humidity, equipment parameters) and abnormal situations.
3、 Technical requirements and operating standards
Equipment performance
Repeatability: The roughness rate repeatability is less than 1%, and the repeatability range of the whole grain rate is ≤ 1.5%;
Automation: equipped with weighing, automatic calculation, data saving, and printing functions;
Compatibility: Can be integrated with information collection and control systems, supporting manual or automatic data upload.
Operating Specifications
Balance and stability: Maintain equipment balance and avoid shaking during the testing process;
Zero calibration: reset to zero before each measurement to avoid error accumulation;
Cleaning and maintenance: Clean the grain storage tank and rice milling room after each measurement to ensure hygienic conditions.
error control
Sample uniformity: Ensure uniform mixing of samples and avoid sampling deviation;
Equipment troubleshooting: Regularly check the accuracy of the scale, the deformation of the groove, and the malfunction of the measuring device;
Visual error avoidance: Using automated equipment to reduce manual evaluation errors.