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- Xiros, Charilaos, 1973, et al.
(författare)
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Biotechnological potential of brewers spent grain and its recent applications
- 2012
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Ingår i: Waste and Biomass Valorization. - : Springer Science and Business Media LLC. - 1877-2641 .- 1877-265X. ; 3:2, s. 213-232
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Forskningsöversikt (refereegranskat)abstract
- Purpose Brewers spent grain (BSG) is a by-product of the brewing process corresponding to around 85% of total by-products generated. The great number of publications over the last 5 years, on the biotechnological applications of BSG, represents the increased scientific interest on it. This critical, state of the art review aims at gathering and analysing the most recent scientific efforts on the biotechnological potential of Brewer's spent grain and on its evaluation as a feedstock for high added value products. Methods The assiduous bibliographic retrospection focused on the latest scientific reports. The consideration of all relevant scientific articles was thorough and critical. The classification of the scientific efforts was made not only according to the end-products but also according to the biotechnological approach adopted. Results BSG has been used in a wide range of biotechnological applications such as substrate for enzymes production, as a source for value-added products (antioxidants, monosaccharides, oligosaccharides, xylitol, arabitol, bioethanol, biogas or lactic acid) or for the production of functional proteins and lipids. Its applications as a carrier in various bioprocesses have also been reported. Conclusion The implementation of BSG's fractionation in industrial scale seems to be the next step in BSG's exploitation. A fractionation process which allows the exploitation of biomolecules belonging to different classes, produced from one feedstock (BSG) may be used as a pattern for the implementation of the biorefinery concept in industrial scale, as long as the methods adopted ensure the functionality of the potentially valuable components.
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- Xiros, Charilaos, 1973, et al.
(författare)
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Comparison of strategies to overcome the inhibitory effects in high-gravity fermentation of lignocellulosic hydrolysates
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 65, s. 79-90
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Tidskriftsartikel (refereegranskat)abstract
- High-gravity (HG) technology aims at generating final ethanol concentrations above 50 kg m(-3) in order to reduce the cost of the distillation step. The generation of higher amounts of inhibitors during the pretreatment step is one of the challenges that accompany the increase in initial dry matter. Detoxification of spruce hydrolysate, adaptation of the cells before fermentation, supplementation with nutrients, and washing of solids were the strategies compared in this study. They represent different approaches to cope with the inhibitory effects, and we compared their efficiencies using a thermotolerant strain of Saccharomyces cereuisiae at temperatures from 30 degrees C up to 40 degrees C. The dilute acid-pretreated spruce used as substrate in this study was not fermentable under HG conditions (200 g kg(-1) water-insoluble solids) when no improvement method was applied. In HG simultaneous saccharification and fermentation at 30 degrees C combined with a 24 h pre-hydrolysis step, the detoxification of pretreated spruce with reducing agent (Na2S2O4) gave the best result with an ethanol yield of 57% (on total sugars) of the maximum theoretical and a volumetric productivity of 1.58 g dm(-3) h(-1). In HG separate hydrolysis and fermentation, nutrients supplementation gave better final ethanol yields than detoxification of the material, reaching an ethanol yield of about 60% of the theoretical (on total sugars). The results obtained, showed an increase in severity of inhibitory effects with temperature increase. Improved cell viability was observed when detoxified material was used and also when yeast extract addition was coupled with adaptation of the cells to the hydrolysate. (C) 2014 Published by Elsevier Ltd.
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| 17. |
- Xiros, Charilaos, 1973, et al.
(författare)
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Evaluation of different strategies to overcome the inhibitory effects at high gravity processes using multivariate data analysis (MVDA)
- 2014
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Ingår i: Lignobiotech III, October 26-29, 2014, Concepcion, Chile.
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Konferensbidrag (refereegranskat)abstract
- High-gravity (HG) technology aims at generating final ethanol concentrations above 50 kg m3 in order to reduce the cost of the distillation step. The generation of higher amounts of inhibitors during the pretreatment step is one of the challenges that accom-pany the increase in initial dry matter. Detoxification of spruce hydrolysate, adaptation of the cells before fermentation, supplementation with nutrients, and washing of solids were the strategies compared in this study. They represent different approaches tocope with the inhibitory effects, and we compared their efficiencies using a thermotolerant strain of Saccharomyces cerevisiae at temperatures from 30oC up to 40oC.The dilute acid-pretreated spruce used as substrate in this study was not fermentable under HG conditions (200 g kg-1water-insoluble solids) when no improvement method was applied. In HG simultaneous saccharification and fermentationat 30oC combined with a 24 h pre-hydrolysis step, the detoxification of pretreated spruce with reducing agent (Na2S2O4) gave the best result with an ethanol yield of 57% (on total sugars) of the maximum theoretical and a volumetric productivity of1.58 g dm3 h−1. In HG separate hydrolysis and fermentation, nutrients supplementation gave better final ethanol yields than detoxification of the material, reaching an ethanol yield of about 60% of the theoretical (on total sugars). The results obtained, showed an increase in severity of inhibitory effects with temperature increase. Improved cell viability was observed when detoxified material was used and also when yeast extract addition was coupled with adaptation of the cells to the hydrolysate. The different fractions of hydrolysates after the application of different treatments were characterised and analysed using MVDA in order to evaluate the differences observed.
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