Sunflower oil cake is a high protein and fat feed source for livestock. It is a by-product obtained from the extraction of oil from sunflower seeds. It can be obtained by mechanical pressing resulting in a „cake“ (see Figure 1) containing 15-20 % oil or by solvent, which increases the quantity of oil. In organic farming, oil may only be extracted by mechanical pressing.
The quality of the oil depends on plant characteristics and on the processing.
The quality of the product can be increased by first dehulling the seeds. This improves the pressing capacity as well as the oil and meal quality. Mechanical extraction is used by producers of speciality oils and smallholder farmers in both developed and developing countries.
Oil presses are used for the mechanical extraction of oil from oilseed crops. The procedure to obtain oil cake is as follows:
• The seeds are delivered to the press where they are crushed and squeezed.
• Under pressure, the oil leaks through the press holes and gathers into the oil repository underneath the press.
• The oil is filtered to remove any solids, which are then cleaned of unwanted substances.
• Together with the oil, an oil-rich press cake is produced.
• After the oil cake has been removed from the press, it is cooled down. It can be stored for up to 3 months.
• This procedure is a current processing technique that produces a good quality oil cake (see Table 1).
In terms of feeding, sunflower oil cake plays an important role in monogastric diets due to its high methionine content, similar to soy cake. It has a high fiber content; the well-structured raw fibre has a positive dietary effect on pigs. Its use in the finishing phase has to be limited because of the relatively high proportion of polyphenolic acids (PUFA), which can lead to an undesirable soft fat consistency in the carcass if the dosage is too high.