Primary Processing

Primary processing of oil-containing material involves pre-treatment processes, oil recovery processes and the extraction and valorisation of valuable compounds from waste streams. Pre-treatment processes, e.g. thermal, enzymatic, electrical and radio frequency, have an important effect on the oil recovery, quality of oil, extraction possibility and quality of valuable compounds from waste streams. Apart from these methods, dehulling, i.e. the separation of the coats from the seeds, can be regarded as a first and indispensable step. To extract and market proteins at an industrial scale, as long as water extraction remains in the domain of research and development, it will be necessary to dehull the seeds before oil extraction in order to extract the proteins and improve the valorisation of these crops. The state-of-the-art of the recovery of (residual) oil from olive, rapeseed and sunflower by-products is reported. The three crops are described with regard to structure, by-products from the oil production and the applied extraction methods. Alternatives for hexane extraction, such as water, iso-propyl alcohol, gas-assisted extraction or supercritical carbon dioxide extraction, could improve the potential of the different oil-bearing crops. The extraction of amino acids and/or protein fractions, which forms the main fraction in the press cakes is described. Also, the possibilities of the production of levulinic acid from the lignocellulosic parts of the crops are investigated.