Pretreatment and pressing process of rapeseed oil
In recent years, the development of rapeseed oil technology has improved, there are rapeseed peeling, cold pressing, and extrusion putting etc. Its products are green rapeseed oil, edible rapeseed meal and so on.
● rapeseed peeling
Rapeseed contains 35-40% oil and about 25% protein, contains about 12-19% seed skin, 30% to 34% crude fiber in the skin, 90% sinensis, pigment, and plant in whole seeds. anti-nutritional substances such as acid and tannin are also mainly present in the seed skin. The rapeseed without peeling to directly produce oil will deepen the color of the oil and increase the difficulty of refining, it will also affect the quality, appearance and palatability of the rapeseed cake, and affect the utilization value of the rapeseed cake protein. Rapeseed peeling can effectively remove the anti-nutritional factors contained in it, increase the protein content of rapeseed cake to about 45%, and the quality of cakes is greatly improved, making the rapeseed cakes comparable to soybean cakes as high quality forage protein resources.
The rapeseed peeling process includes drying of rapeseed, rupture and peeling of rapeseed by impact or other external force, and separation of the skin kernel by screening and air selection.
The peeling rate of rapeseed should be controlled according to the effect of powderiness and separation of skin kernels. The suitable peeling moisture for controlling rapeseed is 7-8%, the peeling rate is 80-85%, and the powder degree is controlled at 2-3%. In the best separation state, the separation effect of <2% in the kernel and ≤2% in the skin can be achieved.
● rapeseed oil cold pressing
The quality of peeled cold pressed rapeseed oil is similar to that of ordinary rapeseed oil hydration degumming and neutralized oil, and can be eaten without refining.
Rapeseed oil cold pressing process:
Rapeseed→ cleaning→ conditioning drying→ peeling and separating→ cold pressing→refining→ cold pressed raflaking and leaching compared to conventional pre-press leaching and simplifies the refining process. Therefore, compared with pre-press leaching, saving 30-40% investment.
● rapeseed peeling extrusion and puffing to produce oil process
Rapeseed→ cleaning→conditioning drying→ peeling separation→ flaking→ conditioning→ extruding→ leaching
After the rapeseed material is cleaned, dried, cooled, peeled and separated, the rapeseed kernel with a skin ratio of about 2% is obtained. The rapeseed kernel is subjected to flaking, and then subjected to conditioning treatment, so that the material reaches a suitable moisture temperature, and then fed into an extrusion extruder. About 39% of the oil in the rapeseed kernel is extracted by the extrusion extruder, and the remaining materials form a porous structure of granular expanded pellets, and the residual oil ratio of the expanded pellets is 27-28% (dry basis). In the case of oil leaching, the expanded pellets have a porous structure, the solvent is easy to penetrate into the material, and the mixed oil is also easy to spread outward.