Separate small potato from other potato at the time of selection in the processing line
How to separate small potato from other potato in the selection process
The separation of small potato is done through a size-calibration process that distinguishes tubers by diameter or weight. After harvesting and washing, the potatoes are started on conveyor belts that distribute them evenly to rollers or perforated plate sizing systems. At this stage, passing through openings of increasing diameter allows smaller fruits to be separated from medium or large ones, allocating them to different containers or processing lines.
Adjustable roller grading machines are among the most popular solutions: the progressive distance between rollers determines the dimensional threshold of separation. Potatoes of lower caliber fall by gravity into the collection lanes below, while the others continue on the belt to the next stage. In more advanced systems, rollers are combined with optical sensors and dynamic weighing systems to detect shape and surface evenness as well, reducing errors and rejects.
The precision of separation depends on three factors: the regularity of the flow on the belt, the calibration of the distance between the rollers, and the correct feed speed. Each potato variety requires a specific setting, especially when working on irregular sizes or crops from different fields. Constant control of line settings keeps calibration consistent throughout the processing shift, reducing variability in the final product.
What parameters define small potatoes and how they are measured online
There is no one definition of “small potato”: the size threshold varies depending on the market and intended use. In general, producers adopt parameters based on tuber cross-sectional diameter and, in some cases, weight. Size is measured in millimeters by mechanical or optical systems, while commercial classification distinguishes tubers by caliber. The following table summarizes the most common reference values.
| Category | Average diameter (mm) | Average weight (g) | Typical Destination |
|---|---|---|---|
| Small potatoes | 35 – 45 | 40 – 70 | “Baby” packaging or industrial processing |
| Averages | 46 – 65 | 80 – 120 | Fresh Market |
| Great | 66 – 85+ | 130 – 180+ | Processing (frying, food industry) |
Separation by diameter is the most reliable solution to achieve smooth calibration. In the most modern sorting systems, 3-D cameras or linear vision sensors measure the size of the tuber in motion, generating a volumetric profile that allows the equivalent gauge to be calculated with millimeter precision. This method, derived from optical grading technologies used for fruit, is also becoming standard in the potato industry because it combines speed and accuracy.
The most delicate parameter remains the management of so-called “intermediates,” those tubers that fall between two size categories. In these cases, the most effective solution is to provide a double calibration phase: a mechanical one for pre-selection and an optical one for final verification. This strategy reduces overlap between classes, increasing the consistency of the packaged product.
How the selection flow is structured to properly separate small potatoes
The operational flow for potato separation follows a precise sequence starting with harvesting and ending with packaging. After receiving the raw product, the potato is subjected to an immersion or spray wash to remove soil and debris. They then go to the pre-selection stage, where larger impurities and foreign bodies are removed. The cleaned product then enters the singulation section, which arranges the tubers on a single feed plane, a necessary condition for dimensional calibration.
Rollers, rotating drums or vibrating belts are used in this phase to ensure uniform flow distribution. The real separation of small potatoes then takes place in the grading machines, where the product passes through modules with apertures or sensors that discriminate diameters. Potatoes that do not exceed the set threshold are automatically diverted to special containers or secondary lines.
Each processing line can be configured with multiple outputs, each corresponding to a gauge category. In the latest generation models, the entire process is digitally controlled, with the ability to vary size thresholds by variety and batch. This flexibility makes it possible to switch, in a matter of minutes, from a process geared toward fresh consumption to one intended for industrial processing, optimizing yield and setup time.
An integrated suction system or final collection belt conveys the different product streams to packaging or storage. Proper separation of smaller potato is not only for aesthetic uniformity, but also affects storage quality, as smaller tubers have different drying times and are likely to deteriorate faster when mixed with larger caliber tubers.
What machinery and technologies to use to separate small potatoes
The choice of the most suitable machinery depends on the processing volume, the level of automation and the destination of the final product. Popular solutions for small potato separation include mechanical rollers systems, drum grading machines, and optical grading machines. Each meets different requirements for precision, range and control.
Sorting roller systems remain the basis of many sorting lines. These are metal or plastic rollers arranged in parallel, with the distance between them gradually increasing. Smaller potatos fall through the spaces while larger caliber ones continue to the next exit. This simple and inexpensive method provides effective separation for uniform lots, but requires frequent cleaning and maintenance to avoid accumulation of soil or debris that can alter precision.
Rotary drum grading machines represent an evolution for plants with high productivity. The perforated drum rotates steadily and uses holes of increasing diameter to grade tubers. It is a robust technology, suitable even for variable field conditions, and offers good stability over time. However, it does not allow the same versatility as optical systems, which are now becoming the standard for those seeking more refined results.
Optical sorters, derived from technologies used for fruits and vegetables, combine linear vision sensors and spectral analysis systems that can recognize the shape, size and surface area of each tuber. In this way it is possible to distinguish not only small potato, but also deformed or damaged ones. Grading is done in real time: software analyzes the profile of each potato and, based on the parameters set, activates an air-jet ejection system that directs it to the correct lanes.
Optical solutions easily integrate with Rollvy calibration or dynamic weighing systems, offering total control over the line. The combination of precision mechanics and digital intelligence enables levels of consistency that are difficult to achieve with traditional systems. In a production environment where yield and quality must coexist, the ability to automatically adjust separation parameters according to variety and batch size is a real competitive advantage.
| Technology | Principle of operation | Benefits | Limits |
|---|---|---|---|
| Grading machines rollers | Mechanical separation by variable distance | Reliability, simplicity, low consumption | Lower precision, mechanical wear and tear |
| Rotary drum | Progressive holes on rotating cylinder | High productivity, robustness | Limited adjustments, large footprint |
| Optical sorter | Automatic visual and spectral detection | High precision, flexibility, data traceability | Higher initial cost, training required |
Common mistakes in small potato separation
The first error encountered is failure to calibrate the separation system. Each variety of potato has a different roundness index and density, factors that influence its behavior on the rollers or in the drum. Keeping generic settings leads to uneven results and too high a percentage of “intermediates.” Regular verification of outlet diameters and adjustment to batch characteristics allow high gauge consistency to be maintained.
Another frequent mistake is poor maintenance of the washing and cleaning system. Soil residues, moisture and organic deposits can change the smoothness of tubers and distort separation. Adoption of automatic cleaning cycles and periodic replacement of rubber or steel components significantly improve process stability.
Finally, the absence of control over nutrition flow compromises the quality of selection. Uneven flow rates generate overlaps between potato, reducing the precision of sensors or the effectiveness of mechanical filtering. On the other hand, dosing and singulation systems, which are often underestimated, are essential to maintain flow regularity and take full advantage of line performance.
Small potato separation as a lever of production efficiency
Separating small potato correctly is not just a matter of aesthetics or commercial standard, but a key step in optimizing the supply chain. Small potatoes can be enhanced through dedicated lines intended for “baby” packaging, snacks or industrial processing. Distinguishing caliber classes with precision also means reducing waste, optimizing logistics and standardizing storage times.
With a view to traceability, each calibrated batch can be monitored and managed according to objective parameters: size, weight and shape. This approach enables intelligent feeding to packaging or processing departments, increasing the predictability of production. It is a concrete example of how technology, consistently applied, transforms a seemingly simple process into a strategic lever for quality and business profitability.
Separating small potato from other potato thus becomes a true precision practice. Not an ancillary operation, but a key step in ensuring that each tuber finds its ideal destination, and that the farmer’s labor translates into value, not variability.