Inhomogeneity in the lauter tun: a chromatographic view

The purpose of lautering in beer brewing is to separate the wort, which contains soluble malt components from the solids, the brewer’s spent grains. Lautering is a critical point in wort production and its primary objective is the efficient recovery of extract. Lautering is a special type of cake filtration; the particle sedimentation behavior of the mash results in an inhomogeneous filter cake whose structure has an impact on its chemical composition. Components of interest within the filter cake are polysaccharides, such as starch byproducts, β-glucan, and arabinoxylan, as well as proteins, lipids, polyphenols, and metal ions. The distribution of these components within the inhomogeneous filter cake is presented in this review. Lautering is a combination of separation and extraction. During extraction, the solubility of each filter cake component is different. Therefore, in this paper, lautering is considered from a new angle—a chromatographic viewpoint. The initial concentration of the components in malt is compared to their degree of retention in the filter cake and extraction into the wort. Differences in the analyses of brewer’s spent grains due to different sampling points within the filter cake are addressed in this review. This new information is important for the use of spent grains in biotechnological processes and enables a more accurate comparison of components from different brewer’s spent grain analyses.