The increasing global energy requirement is shifting the scientific attention from fossil to bio-based resources to produce energy and chemicals. Lignocellulose is the most abundant natural and renewable resource on Earth. A considerable amount of such material is generated as waste through agricultural practices mainly from various agro-industries. Agriculture food processing wastes (AFWs) are potential feedstock for biorefinery processes being economic and eco-friendly. Coffee silverskin (CSS) is anAFWsproduced during the coffee beans roasting process. These vegetable residues are recalcitrant to enzymatic and microbial attacks, limiting their use for biorefinery applications. Pretreatment delignification methods are required to facilitate the enzymatic hydrolysis of AFWs aimed at the recovery of monomeric fermentable sugars from these residues. The aim of this study was to develop a pretreatment process by using ultrasound and mild alkaline solutions for the effective separation of lignin and cellulose to improve the sugar yield from CSS. The effects of sonication time, biomass loading, sodium hydroxide concentration and residence time in autoclave, were studied using Response Surface Methodology (RSM). A maximum reducing sugar yield of 0.6 gsugar/gtotal sugar in pretreated biomass was obtained with 5min sonication, 11% w/v biomass loading, 5% w/v NaOH and 75 min autoclave. Analysis of liquid after pretreatment revealed that fermentation inhibitors like furfural, HMF, ferulic and p-coumaric acid were absent or present in non-toxic concentrations for various Clostridium sp. Moreover, a phenolic content of 25.3 mgGAE/graw CSS was found. Changes of biomass structural properties after pretreatment were highlighted by SEM and XRD analysis.

Pretreatment of coffee silverskin with ultrasound and mild alkaline solutions for enhancement of sugar yield

Alessandra Procentese;
2018

Abstract

The increasing global energy requirement is shifting the scientific attention from fossil to bio-based resources to produce energy and chemicals. Lignocellulose is the most abundant natural and renewable resource on Earth. A considerable amount of such material is generated as waste through agricultural practices mainly from various agro-industries. Agriculture food processing wastes (AFWs) are potential feedstock for biorefinery processes being economic and eco-friendly. Coffee silverskin (CSS) is anAFWsproduced during the coffee beans roasting process. These vegetable residues are recalcitrant to enzymatic and microbial attacks, limiting their use for biorefinery applications. Pretreatment delignification methods are required to facilitate the enzymatic hydrolysis of AFWs aimed at the recovery of monomeric fermentable sugars from these residues. The aim of this study was to develop a pretreatment process by using ultrasound and mild alkaline solutions for the effective separation of lignin and cellulose to improve the sugar yield from CSS. The effects of sonication time, biomass loading, sodium hydroxide concentration and residence time in autoclave, were studied using Response Surface Methodology (RSM). A maximum reducing sugar yield of 0.6 gsugar/gtotal sugar in pretreated biomass was obtained with 5min sonication, 11% w/v biomass loading, 5% w/v NaOH and 75 min autoclave. Analysis of liquid after pretreatment revealed that fermentation inhibitors like furfural, HMF, ferulic and p-coumaric acid were absent or present in non-toxic concentrations for various Clostridium sp. Moreover, a phenolic content of 25.3 mgGAE/graw CSS was found. Changes of biomass structural properties after pretreatment were highlighted by SEM and XRD analysis.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4771487
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