The aim of this study was to investigate the compressibility of sunflower kernels and its material flow during the mechanical extraction of oil-rich, low-fibre oil seeds. This work was carried out with shelled sunflower kernels. On an industrial scale, the pressing of these products is mainly characterised by significant slowing down of the flow rate and unsatisfactory flow of the oil out of the cage.
The aim of this work is to obtain a good de-oiling on the whole cage but also to have a fat content lower than 10% in the meal. For this purpose, a hypothetical method was set up in order to study the impact of different parameters on the quality of the pressing. These include the speed of rotation, the temperature, the spacers between the bars of the cage and the water content of the kernels. All these parameters influence the behaviour of the press and the quality of the cake.
For the study of the flow of materials inside the press, the almonds are coloured red and between each test, the cage was opened in order to take several samples which were analysed by NMR spectrometry method in order to determine the fat content along the shaft of the press.
This prospective work has made it possible to identify the parameters that have the greatest impact on pressing quality and to carry out optimisation tests in order to produce pressing scales with a fat content of less than 10%, preserving proteins by limiting heating while allowing the press to operate at its nominal rate.
The next step envisaged will be to carry out a "scale up" on a larger press by extrapolating the parameters identified during this project.
Contact: David Matéos, Head of 1st transformation department, ITERG.