Brewery’s spent grain

Comparison of Two Posthydrolysis Processes of Brewery s Spent Grain Autohydrolysis Liquor to Produce a Pentose-Containing Culture Medium+... 

Brewery s spent grain (BSG) is the residue of malt and grain remaining in the mash kettle after the liquefaction and saccharification of starch to produce the wort. Since the manufacture of just 1 L of beer leads to about 0.04 kg of dry BSG, this material is largely available throughout the year. BSG is only used in low added-value applications such as feed, and therefore upgrading solutions are needed. 

Optimization of Brewery s Spent Grain Dilute-Acid Hydrolysis for the Production of Pentose-Rich Culture Media... 

Index Entries Brewery s spent grain dilute-acid hydrolysis pentose-rich media Debaryomyces hansenii. 

Lignocellulosic agroindustrial byproducts are renewable, widespread, and generally an inexpensive source of biomass. Brewery s spent grain (BSG) is a disposal residue generated throughout the year in large amounts, for... 

Yeast Biomass Production in Brewery s Spent Grains Hemicellulosic Hydrolyzate... 

Keywords Debaryomyces hansenii Biomass Single-cell protein Hemicellulosic hydrolyzate Brewery s spent grains Agro-industrial residues upgrading Yeast extract... 

In this work, we comparatively assessed the potential of brewery s spent grains (BSG) hemicellulosic hydrol3 zate for YE and SCP production using D. hansenii, K. marxianus, and P. stipitis. 

Brewery s spent grains macromolecular composition varies much, as it is not a defined product from a single raw material rather, it is a by-product fix)m a mixture of several raw materials that can be processed in the brewery under quite variable conditions. The average composition of the used BSG is presented in Table 1. 

Table 1 Average macromolecular composition of brewery s spent grains on a dry weight basis (%).

Table 2 Composition of brewery s spent grains hydiolyzate.

Table 3 Kinetic and stoichiometric parameters, of P. stipitis, K. marxianus, and D. hansenii growth in supplemented brewery s spent grains hydrolyzate.

Table 5 Amino acid composition (% of total protein) of D. hansenii biomass grown on brewery s spent grains hydrolyzate as compared to the FAO standard. ...

Table 6 Fatty acid composition of D. hansenii biomass grown on brewery s spent grains hydrolyzate.

In this publication the rese ch performed within the framework of the PhD-research concerning the characterisation of complex xylo-oligosaccharides from xylan rich by-products (2) is reviewed. The separation and structural features of differently substituted xylo-oligosaccharides obtained from hydrothermally treated wheat bran, brewery s spent grain, com cobs and Eucalyptus wood is described. 

Table I Sugar content and composition of the hydrolysates obtained after hydrothermal treatment (160 C 60 min 8-10 g/g) of wheat bran, brewery s spent grain, corn cobs and Eucalyptus wood (5,9).

As for wheat bran, during the hydrothermal treatment of brewery s spent grain and com cob arabinose is released from the xylans present. However, in the hydrolysates of brewery s spent grain still quite some XOS and xylan-fragments containing arabinose are present (Ara/Xyl-ratio=0.3). 

In the hydrolysates of com cobs non-substituted and O-acetylated xylan-fragments are accumulated. In both the hydrolysates of brewery s spent grain and com cobs monomeric xylose and arabinose are present as well. 

Structural characteristics of xylo-oligosaccharides present in brewery s spent grain and Eucalyptus wood hydrolysates... 

Figure 3 MALDI-TOF mass spectrum of endoxylcmase I-digested brewery s spent grain pool B. Oligosaccharides are analysed as sodium-adducts (P = pentose Ac = 0-acetyl).

In the MALDI-TOF mass spectra of the original hydrolysate of brewery s spent grain used for fractionation the masses corresponding with C>-acetylated XOS were hardly present. Most likely, if O-acetylated XOS (DP < 20) were present in the hydrolysate their concentration was too low to detect by MALDI-TOF MS. Additionally, O-acetylated xylan-fragment having a DP higher than 20 are difficult to detect by MALDI-TOF MS. 

Purification of the hydrothermally treated brewery s spent grain also resulted in a pool containing charged xylan-material (9). Most likely, the recovered xylan-fragments were still partly substituted with (4-0-methyl-)glucuronic acid residues. However, the charged pool represented less than 1 % of the material obtained after hydrothermal treatment of brewery s spent grain and was not studied in more detail. 

HPAEC, RP-HPLC, RP-HPLC-MS, MS, RP-HPLC-NMR and NMR spectroscopy showed to be very useful for the separation and characterisation of the detailed structures of the substituted XOS. Furthermore, the use of these methods resulted in the recognition of some structural features, which have not been reported before to our knowledge. 0-acetyl substituents were found to occur not only in hardwood xylans as shown in literature, but also in xylan-fragments obtained from cereals (brewery s spent grain). Additionally, 2-0- or 3-0-acetyl substituted terminal xylosyl residues were analysed by NMR to occur in XOS present in the Eucalyptus wood hydrolysates. The complete structural characterisation of several O-acetylated XOS obtained from Eucalyptus wood hydrolysates was established by using (RP-HPLC-)NMR. 

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