Realizing the potential of rapeseed seed processing by pressing and extrusion

In recent years, rapeseed production in both Belarus and Russia has increased many times. In Belarus, in 2024, for the first time, the gross harvest of rapeseed exceeded 1 million tons after refinement, and in Russia it amounted to 4.66 million tons. Large gross collections and export restrictions on rapeseed predetermined the need for its processing. Along with oil extraction plants, rapeseed is also processed in many farms and enterprises, including feed mills. This is due to the fact that protein components from soybeans are quite expensive. Enterprises install various pressing equipment and mechanically produce rapeseed oil (edible, feed, technical) and cake, which is mainly used for feed for farm animals and poultry. It should be noted that currently the main focus in the processing of rapeseed and other oilseeds for fodder purposes is shifting towards improving the quality, nutritional value and digestibility of the resulting cake.

In relation to ruminants, for which rapeseed cake is the main dairy product, when evaluating its quality indicators and forming feeding rations, the ratio of protein in the cake that is cleaved and not cleaved in the rumen is taken into account, followed by its transit into the intestine for further digestion. In this case, when processing rapeseed seeds, the main goal is to ensure the maximum possible digestibility of the cake and thereby improve feed conversion.

This problem is not solved by the use of cold-pressing technology according to the scheme: pre-press → final press, with the production of oil and cake, since protein digested in the rumen predominates in such cake. Another method of processing rapeseed seeds is the classic hot—pressing technology using rolling machines, roasters and presses, it is characterized by a high oil yield. However, due to the high temperature and exposure time of the mint in the roasters, with low humidity of the raw materials, the cake obtained at the outlet contains a significant amount of protein not cleaved in the rumen. As a result, such cake is not completely digested in the intestine, so it is of less benefit to the animal.

Based on the analysis of oilseed processing technologies, including rapeseed seeds, new design solutions and test results, Globalprodservice has developed a modern, highly efficient double-pressing technology with extrusion and created complete production lines with a capacity of 0.5, 0.75 and 1 t/h for input raw materials.

The double-pressing and extrusion lines include all the necessary equipment that allows the production of rapeseed oil of two types (cold and hot pressed) and extruded cake with bypass protein. Today, this is the best technological solution, especially for processing rapeseed seeds. The use of these lines makes it possible to process approximately 4,000 tons to 8,000 tons of seeds with round-the-clock operation and equipment loading 330 days a year. To ensure their loading, two to four thousand hectares of rapeseed acreage with an average yield of 20 kg/ha will be required.

The processing process using double pressing technology with extrusion includes five main
stages:
• seed preparation (pre-cleaning and heating);
• pre-pressing (pre-pressing →cold pressing of oil);
• cake extrusion;
• final pressing (hot pressing of the extrudate);
• Oil filtration.

The complex of the pressing section of the technological line for processing rapeseed seeds by double pressing with extra-
With a capacity of 1 t/h, it consists of a GL-RP-1000 oil press or two GL-RP-500 presses, a GL-E-1000 extruder and a GL-RP-1000 final pressing press. The electric drive of the presses has a frequency control for changing the rotation speed of the screw shaft. Rapeseed seeds and cake are transported by several screw conveyors. For ease of operation and maintenance, our equipment has a single-tier layout, covers an area of about 100 square meters, while the building height is only 6 m. Thanks to this layout scheme, the lines from Globalprodservice can be installed in almost any suitable room of a household or enterprise.

The rapeseed processing line operates as follows (Fig. 1). Seeds are sent from storage to a separator for additional purification and reduction of the weed content in them (up to 2-3%). Then they are sent to a horizontal type normalizer, in which they are heated at an elevated temperature. In winter, as well as to ensure the operation of the pre-press in optimal mode, we recommend heating rapeseed seeds to 30 ° C. It is impractical to heat the seeds to higher temperatures, as this leads to a slight change in the viscosity of the oil in them. Next, the heated seeds are transferred to the receiving funnel of the GL-RP-1000 pre-press hopper. On the pre-press, rapeseed oil is pressed at a mild temperature regime not exceeding 60 ° C. It flows through the gaps of the seed chamber into the pan, and then through the nozzle at the bottom of the press is discharged into a special container for collecting cold-pressed oil. A cake with an oil content of 25-30% comes out of the pre-press, which has already been mechanically destroyed and partially heated due to friction in the press (1st stage of pressing).

The cake is fed by a screw conveyor into the GL-E-1000 extruder. Due to its preliminary preparation
(crushing and heating) The extrusion process takes place with lower energy consumption. In the extruder, the cake is heated to a temperature of 115–120 ° C due to friction and pressure. It should be noted that the extruder is one of the main units of the equipment set. It is the extrusion process that largely determines the quality of rapeseed cake and the ratio of cleavable and non-cleavable protein in it, as well as its digestibility.

Depending on the purpose and type of crops being processed, the company offers several models of the GL-E-1000 extruder (five in total), differing in the power of the electric drive, the length of the barrel and the screw part of the screw, which makes it possible to stably maintain the set temperature of the product at the outlet of the extruder. Unlike heating rapeseed mint in braziers, extrusion is a very gentle process: due to short-term exposure to high temperature and pressure, there are no significant structural changes in the cake extrudate. However, for maximum oil extraction, it is sufficiently destroyed and prepared for final pressing in a GL-RP-1000 hot-pressed screw oil press (2nd stage of pressing).

At the same time, the temperature in it can reach 125 ° C. At the exit from the final pressing press, the cake has an oil content of about 9%. If necessary, it is additionally crushed, and then fed into the GL-OE-1000 cooler using a screw conveyor. The chilled product is transported either to a temporary storage location or directly to a finished product warehouse. For safe storage of the cake, its temperature after cooling should not exceed the ambient temperature by more than 10 ° C.

Hot-pressed oil can be sent both to a combined collection container with cold-pressed oil for subsequent filtration (purification from mechanical impurities), and to a separate filtration using a vertical pressure plate filter (Fig. 2). Scales are provided to account for the amount of pressed oil in the rapeseed processing line. The oil pressed using this technology and the cake obtained at the same time retain the natural antioxidants tocopherols, which help to increase the shelf life of products.

Control of the operation of pressing and extrusion equipment, as well as all technological processes in general-
som processing of rapeseed seeds is carried out through automated process control systems. The distinctive features of the double-pressing and extrusion production lines manufactured by Globalprodservice are the use of equipment at reasonable prices, which allows processing enterprises to avoid purchasing expensive foreign analogues and thereby reduce the cost of rapeseed oil and cake produced. The extruded cake produced on this production line has high nutritional qualities, is characterized by sterility and good digestibility. Not only does it have a reduced content of anti—nutrients, but most importantly, structural changes in proteins have occurred, as a result of which the amount of protein not cleaved in the rumen (bypass or protected) exceeded the level of cleavable protein.

The economic efficiency of using extruded rapeseed cake with bypass protein in cattle feeding is expressed in the following:
• an increase in dairy productivity of cows by an average of 6-8%;
• receiving (additionally) at least 1 liter of milk from each dairy cow when using
1 kg of extruded rapeseed cake in the feeding diet;
• reducing the consumption of mixed feed by 6-10% in terms of 1 liter of milk due to an increase in the proportion of bypass
protein and its absorption in the intestine.

Thus, the combination of double pressing and extrusion operations in the rapeseed processing line from Globalprodservice provides a total rapeseed oil yield comparable to that of hot-pressed oil, due to the destruction of the fatty cellular structures of the seeds and their heating. The high efficiency of oil extraction, the production of extruded oilcake with improved nutritional properties, as well as the cost-effectiveness and environmental friendliness of processing make this technology in demand in conditions of growing demand for rapeseed oil and high-protein cake. With the further development of technology and equipment improvements, double extrusion pressing lines will become more accessible not only for on-farm processing in small and medium-sized enterprises, but also for industrial
processing.

Globalprodservice is constantly working to improve the technical characteristics
of the equipment and quality indicators for oil yield and residual oil content of the cake.

Contacts: Republic of Belarus, Minsk; +375 29 1493751; sales@globalprod.by