Rice Testing

1. Inspection items
Appearance quality: including the shape, size, color and transparency of rice grains. Long-grain rice and round-grain rice have their own characteristics. Normal rice has a bright and uniform color, no obvious yellow grains or chalky grains, and high transparency. These appearance characteristics can initially reflect the freshness and quality grade of rice. For example, high-quality Northeast rice is crystal clear.

Nutritional ingredients: Test the content of protein, fat, carbohydrates, vitamins and minerals. Protein content affects the taste and nutritional value of rice. Vitamin B group and other nutrients are essential for human metabolism. Different varieties of rice have different nutrition. Understanding the nutritional ingredients is convenient for consumers to purchase according to their needs.

Processing accuracy: Measures the degree of rice processing such as shelling and milling. For example, brown rice retains more outer tissues, rich in nutrition but rough in taste; polished rice has a delicate taste but some nutrients are lost. The degree of skin retention and the rate of skin retention in the back groove are tested to determine whether the processing accuracy meets the standard.

Safety indicators: Focus on testing the content of heavy metals, such as lead, cadmium, and mercury. Long-term intake of excessive heavy metals is harmful to health. There are also pesticide residues. During the growth of rice, drugs may be used to prevent and control pests and diseases. Excessive residues endanger food safety and must be strictly controlled.

2. Testing methods
Appearance inspection: Observe the shape and color of rice grains with the naked eye or with the help of a magnifying glass, and compare them with standard samples; use a colorimeter to quantify the color difference of rice, and accurately judge the freshness and quality consistency.

Nutritional component analysis: Use chemical analysis methods, such as the Kjeldahl nitrogen method to measure protein, digest the rice sample, and determine the nitrogen content to infer protein; use high-performance liquid chromatography to measure vitamin content and accurately quantify each nutrient.

Processing accuracy determination: Combine sensory evaluation with instrument measurement to observe the condition of the rice grain epidermis and endosperm sensorily; instrument measurement uses a rice mill to grind rice for a certain period of time, and compare the weight changes before and after to infer the processing accuracy.

Safety index detection: Atomic absorption spectroscopy is used for heavy metals to atomize the sample to absorb characteristic light, and the content is measured according to the absorbance; gas chromatography-mass spectrometry is used for pesticide residues to separate and identify residual pesticide components in complex mixtures.

3. Testing standards
There is GB/T 1354 "Rice" national standard in China, which regulates the quality requirements and inspection methods of various types of rice; the industry also has standards for special products such as organic rice and selenium-rich rice. Internationally, the Codex Alimentarius Commission standard guarantees the quality standards of international rice trade, so that global rice has "quality" to follow.

4. Significance of testing
For consumers, testing ensures that safe, nutritious and good-tasting rice is purchased to protect the health of the family's table. For producers, planting and processing are optimized according to testing to enhance product competitiveness. From the perspective of market supervision, strict testing purifies the market, prevents the influx of inferior rice, and ensures the steady development of the grain industry.