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Hidden factors: What are the factors that affect grain quality?
In agriculture, the quality of grain is affected by the grain used. For example, in alcohol production, the chemical composition of grains, such as starch content, is crucial; while in food and feed manufacturing, the properties of proteins, oils and sugars are important considerations. In the milling industry, the overall soundness of the grain is the most important quality indicator. For grain farmers, high germination rates and seed dormancy time are the dominant characteristics, while for consumers, characteristics such as color and flavor are the most important factors.
The overall assessment of grain quality is influenced by several factors, including: farming practices, harvest timing and type, postharvest handling, storage management and transportation practices.
The characteristics of grain quality can be summarized into ten main factors: (i) Uniform moisture content (ii) High kernel weight (iii) Absence of foreign matter (iv) Proportion of kernels without color changes, breakage and damage (v) Low breakage (vi) High milling quality (vii) High protein and oil content (viii) High viability (ix) Absence of aflatoxins (x) Absence of presence of insects and molds.
External and internal factors affecting grain quality
Grain quality is evaluated based on two main types of factors: external factors and internal factors. External factors include: age, broken grains, immature grains, foreign matter, infected grains, and moisture content. Internal factors include: color, composition, bulk density, odor, aroma, size and shape. Color is an important basis for characterizing grains and is often used in the wheat trade.
The composition of grains plays an important role in evaluating and marketing grains. The main components include: carbohydrates, proteins, lipids, minerals, fiber, phytic acid and tannins.
Bulk density is defined as the ratio of the mass of a grain sample to its specific volume, including the spaces between the grains. Size and shape are important factors in grain quality and grade because they vary greatly between different grains and between different varieties of the same species. These characteristics are key factors in the grading of rice.
Grains and Grains Specifications
Grading and specification systems for cereals ensure that specific batches of cereals meet the standards of food regulatory agencies, such as the FDA in the United States and the FSA in the United Kingdom. In many countries, the grading of cereals relies on four main attributes: (i) litre (test) weight (ii) moisture content (iii) percentage of foreign matter or broken kernels (iv) proportion of damaged kernels.
Test Weight
Test (liter) weight, also known as volumetric weight, is one of the simplest and most traditional standards for assessing grain quality and measuring grain bulk density. It is an indicator of general grain quality, with higher test weights generally associated with higher quality and lower test weights corresponding to lower quality. Test weight is affected by many factors, including moisture content, frost damage, maturity, planting and harvesting conditions, drying conditions, kernel damage and variety.
Moisture content
Moisture content is another important factor in determining grain quality: the amount of moisture is expressed as a percentage. It does not directly affect grain quality, but if the moisture content exceeds the recommended value for storage, the grain will rot, which will indirectly affect the quality.
Foreign Matter
The presence of foreign matter, which refers to foreign matter other than grain, such as sand, rocks, microplastics, metal and glass, is an important factor in grain grading and sorting. If foreign matter exceeds a set percentage, the batch of grain will be rated as low grade and may even receive a price discount or be rejected.
Damaged kernels
It is inevitable that damaged grains will affect the value of the grain. Simply put, visible damage will affect the transaction price. Each grain grading standard has an upper limit for damaged kernels. For example, for wheat, damaged kernels must not exceed 0.4% of the total weight.
Non-grain standard attributes
In the U.S. grain standards, important non-grain standards include: (i) break susceptibility (ii) milling quality (iii) seed viability (iv) nutritional value (v) mold count and carcinogen content (vi) insect infestation and damage.
The mass of a meter
Rice is one of the world's major cereal grains, and as different cultures have evolved, the definition of its quality has often depended on cooking habits and regional usage requirements. As the quality of rice is improved, many countries are trying to define the quality of rice by setting clear standards. The quality of rice can generally be assessed by four main criteria: milling quality, cooking and eating quality, nutritional quality, and cleanliness, soundness, and purity.
In addition to the physical properties of rice, the nutritional content of rice is also an important indicator of quality. The variables of these components depend on many factors, including plant variety, environmental conditions, fertilization method, degree of grinding and storage conditions.
As we pay more attention to the factors that influence grain quality, how will these subtle differences translate into real changes in agricultural production?
