High-quality and stable yields begin with pure, homogeneous grain. Seeds undergo a complex processing sequence: primary and secondary cleaning, removal of weed impurities, sorting by specific weight, calibration, and optical sorting. Each step reduces the risks of microbial contamination, mechanical damage, and variability in extract yield. This article will examine each stage in detail.

Primary Cleaning

Once the seed harvest is complete, the grain must undergo primary cleaning to remove large impurities and reduce the dust load to a safe level. This is done by passing the raw material through sieve separators (with large and medium screens) and aspiration channels (aspiration is the process of removing light particles using an air stream). This stage removes straw, stems, small stones, dust, and clumps of soil.

Primary cleaning reduces equipment wear, prevents self-heating, and lowers the risk of mold formation.

Secondary Cleaning

However, a single cleaning pass is insufficient. The grain requires secondary processing to achieve the required purity level before more precise sorting. Secondary cleaning stabilizes the fractional composition and increases the efficiency of subsequent operations.

Secondary cleaning uses finer screens, brush cleaners to remove adhered particles, and repeated aspiration. It removes fine mineral particles, broken kernels, weed seeds, and residual husks.

Removal of Weed Seeds

The next stage is to eliminate weed seeds and toxic impurities. This is achieved using a combination of sieves with calibrated holes and air channels to separate particles by size and aerodynamic properties. Magnetic separators are also used to remove ferromagnetic particles.

Sorting by Specific Weight

Specific weight is an indicator of a material's density relative to water.
Sorting by specific weight is necessary to separate immature, damaged, and microorganism-infected kernels. These defective grains yield an unstable extract and impart off-flavors to the finished beer.
This sorting is performed using gravity tables, which create a vibro-pneumatic fluidized bed: an air stream suspends the mass, while vibration separates particles based on density and friction. Dense, fully-developed grains move in one direction, while light impurities move in another.

Calibration

Calibration separates grains into fractions based on size (thickness, width) to create a uniform batch, ensuring synchronous water absorption and germination.
This stage uses multi-deck calibration sieves. Specific sieve "maps" are also selected according to the particular crop (barley, wheat, etc.).

Optical Sorting

Optical sorting removes grains from other crops and defective kernels that are visually different in color, shape, or texture. Even small amounts of impurities (e.g., oats in barley, discolored kernels) affect the protein balance, lipoxygenase activity, foam stability, and flavor purity. Therefore, it is crucial not to neglect this stage.
The optical sorting process involves using high-speed cameras and LED lighting to analyze each kernel based on its spectrum (RGB/NIR). Undesirable objects are ejected by compressed air micro-valves within milliseconds. Threshold values and color masks are configured according to the crop and the batch's intended use. Modern technological solutions provide high throughput with a low rate of erroneous rejections and fine-tuned sorting recipes.


Seed processing is a technologically complex, multi-stage procedure. Today, Grainrus AGRO produces elite, high-quality seeds from both imported and domestic breeding programs, leveraging modern technology and a comprehensive five-stage cleaning process.