Mild disclosure and fractionation of barley

1. Mild disclosure and fractionation of barley PhD. Student: Laura van Donkelaar Phone: +31 317 485096 Thesis advisor: Prof. dr. ir. R.M. Boom E-mail: laura.vandonkelaar@wur.nl Supervisor: Dr. ir. A. J. van der goot URL: www.wageningenur.nl/fpe Research group: Food Process Engineering Research school: VLAG Supported by: ISPT Period: Nov 2011- Nov 2015 • Introduction • Many food processes are based on traditional methods. Though proven, they might not always be the most efficient way to produce the foods. Beer brewing is a prone example of a traditional process, Barley, together with some other materials is processed into beer. At the end of the process, components which have a negative impact on the final product quality (certain proteins and polyphenols) are removed by filtration. Due to the high water content in beer, this filtration step requires the processing of a large volume. • An alternative way is to separate undesired components from the raw material before processing. Then, it would be possible to use only the desired components (in particular starch) as a starting material for the brewing process. Dry fractionation is a mean to do this in a way that requires little energy and water compared to other fractionation methods. • Aim • The aim of this project is to investigate the potential to selectively remove the components from barley which negatively affect the end product quality by using mild fractionation. The techniques for this should be economic, sustainable and practical. • Research • Mild processes are defined as processes which do not affect the native properties of the barley components and use less energy than conventional processes. The reason for developing these processes is to make optimal use of the raw material barley, therewith increasing the process efficiency. • Dry fractionation is one of the methods to fractionate barley into its constituents. It consists of two steps. The first step is the mechanical disclosure of the barley kernel, which can be achieved by milling. The milling should lead to components being separated from each other. The second step will lead to the actual fractionation and could be achieved by methods such as sieving or air classification. • Figure 1 shows two examples on how the barley could be disrupted during milling. For illustration, the barley is simplified as a starch in a protein matrix, surrounded by a cell wall. • Figure 1. Possible breaking patterns of barley when milling. Yellow: Starch. Brown: Matrix surrounding starch (protein). Black: Cell walls (β-glucan). • In example A, the starch is released from the matrix and cell wall material, and can therefore be separated with mild methods. In example B, the breakage happens trough the matrix and starch kernels, which allows no separation by methods like sieving or air classification. • In order to optimize the disclosure and separation process, it is thus essential to investigate the mechanical properties of the barley. • These properties can change for different starting conditions of the raw material, like its temperature and moisture content. This controls whether the constituents of the barley are in e.g. the rubbery (elastic) or the glassy (brittle) state. • So the state of the material defines it mechanical properties, which in turn influence the milling behaviour and thus the separation behaviour of the milled flour. In this study, the optimal conditions for the separation of barley constituents are investigated. In addition, the consequences for the brewing process will be studied. • Acknowledgement • This study is supported by ISPT, the institute for sustainable process technology. B A