2024-03-28T16:10:06Zhttps://riubu.ubu.es/oai/requestoai:riubu.ubu.es:10259/66582022-05-20T13:21:59Zcom_10259_4244com_10259_5086com_10259_2604col_10259_4569
Alonso Riaño, Patricia
Melgosa Gómez, Rodrigo
Trigueros Andrés, Ester
Beltrán Calvo, Sagrario
Sanz Díez, Mª Teresa
2022-05-16T09:15:00Z
2022-05-16T09:15:00Z
2022
http://hdl.handle.net/10259/6658
Póster presentado en: EIFS2022, the 2nd Iberian Meeting on Supercritical Fluids (2º Encontro Ibérico de Fluidos Supercríticos / 2º Encuentro Ibérico de Fluidos Supercríticos), to be held on 28.February - 2.March 2022 in Coimbra, Portugal.
Brewer ́s spent grain (BSG) is the solid by-product generated in breweries after the
mashing and wort filtration process. It comprises about 85 % of the total by-products,
generating approximately 20 kg per 100 L [1]. BSG presents a valuable chemical
composition with a high content of protein and carbohydrates, 5 % of lipids and an
important source of phenolic compounds. Among the different techniques proposed to
valorize BSG, supercritical CO2 (sc-CO2) has become a promising technology to process
biomass. The main aim of this work was to assess the effect of sc-CO2, after BSG oil
extraction, on the subsequent enzymatic hydrolysis to hydrolyze the polysaccharide
fraction into monomeric sugars by comparing the sugar yields of sc-CO2 and non-scCO2
treated BSG.
After sc-CO2 treatment at 40 MPa and 80 oC, the raffinate obtained was subjected to
enzymatic hydrolysis by cellulase at different enzyme dose. At the sc-CO2 extraction the
carbohydrate fraction remained in the raffinate phase after extraction. Glucose yield
increased with enzyme concentration for non-treated and sc-CO2 treated BSG. Higher
yields of glucose were obtained for sc-CO2 treated compared to non-treated sc-CO2 for all
the enzymes concentrations. The percentage increase in glucose yield for sc-CO2 treated
and non-treated BSG was 8, 14 and 18 % for the three cellulase concentrations essayed
in this work, 0.25, 0.5 and 1 %, respectively. The hydrolysis kinetics for xylose and
arabinose have been also determined for non-treated and sc-CO2 treated BSG at 1 % of
cellulase dose. Although not big differences were observed in the final sugar yield in the
hydrolysates, the initial hydrolysis rate were significant higher for the sc-CO2 treated BSG
than for the untreated samples. The higher enzymatic hydrolysis rate and yield obtained in the raffinate-BSG after sc-
CO2 treatment compared with non-treated BSG could be attributed partially to the removal
of the lipid fraction. As it has been described in literature [2], fats and oils could influence
the susceptibility of carbohydrates to enzymes. This improvement was also due to surface
morphology modification. The structural and chemical changes of untreated and sc-CO2
treated BSG was assessed by scanning electron microscopy and X-ray powder diffraction
(XRD). Although the XRD pattern after sc-CO2 treatment indicated that the pre-treatment
was not strong enough to modify the BSG crystallinity, the raffinate exhibited an irregular
porosity and lamellar structure. sc-CO2 broke partially some structural barriers allowing
a better enzyme access.
Furthermore, some phenolic compounds were determined in the enzymatic hydrolysates
at the end of the hydrolysis by using 1 % of cellulase (Table 1). It was observed that for
p-coumaric acid and ferulic acid, a concentration 31 and 24 % higher, respectively, was
obtained in the BSG hydrolysates after sc-CO2 treatment, while for vanillin similar
concentration was obtained in both hydrolysates. The concentration of p-coumaric acid
and vanillin after cellulase hydrolysis was lower than the values previously reported for
the same BSG by alkaline, xylanase (1%) and subcritical water hydrolysis [3], [4].
Nevertheless, for ferulic acid, only a higher value was reached for alkaline hydrolysis.
JCyL and ERDF for financial support of project BU050P20
Agencia Estatal de Investigación for financial support of project PID2019-104950RB-I00 / AEI / 10.13039/501100011033
JCyL and ESF for E. Trigueros (ORDEN EDU/574/2018) and P. Alonso-Riaño predoctoral (EDU/556/2019) contracts
R. Melgosa is supported by a Beatriz Galindo Research Fellowship [BG20/00182]
application/pdf
eng
Ingeniería química
Chemical engineering
Modification of brewer’s spent grain after sc-CO2 extraction: improvement of sugar and phenolic compounds release
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