Yield * (%)

Caustic (NaOH) and acid-caustic (HCl + NaOH) treatments have both been previously proposed to prepare ligno-cellulosic yeast carriers from Brewers ´ Spent Grains (BSG) [1]. However, these treatments are time consuming (more than 24 h). Base-treated carriers are more hydrophobic if compared to acid-base treated, enhancing adhesion in one hand, but more floatable and easily washed out from the reactor in the other hand [2]. Thus, a balance between hydrophilic (cellulose) and hydrophobic (lignin) composition in carriers obtained from BSG must be idealized. The aim of this study was to idealize a fast and simple treatment on ligno-cellulosic substrate from BSG. Two types of BSG have been used in this work: dried BSG settle as pellets for animal nutrition and fresh BSG, directly from the beer industry. Both pelleted and fresh BSG were subjected to a series of proposed chemical treatments, as well as to treatments suggested in the literature [1] (Table 1 summarizes the conditions used). Carriers were assessed for cellulose content through high performance liquid chromatography (HPLC) (Varian, Metacarb 67H Column 300 x 6.5 mm). Briefly, approximately 0.5 g of each dried carrier was digested with sulfuric acid. The digested material was settled in glass flasks with water, autoclaved and filtered. Then, the solid