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Pinto M.,University of Aveiro | Coelho E.,University of Aveiro | Nunes A.,University of Aveiro | Brandao T.,Unicer Bebidas SA | Coimbra M.A.,University of Aveiro
Carbohydrate Polymers | Year: 2015

Brewers spent yeast (BSY) is a by-product from beer industry that can be exploited as source of glucans and mannoproteins, with potential biological activities. In order to solubilize these carbohydrate-rich polymeric materials, a sequential extraction with hot water and alkaline solutions (0.1-8 M KOH) was performed. Mannoproteins were mainly (85%) extracted with 4 M KOH whereas glucans were extracted with 8 M KOH and in an amount that accounted only for 34% of total glucose. Final residue still accounted for 34% of the initial glucans and contained 98% of glucose. Cellulase and α-amylase treatments showed the presence of both α- and β-(1→4)-Glc linkages. To promote total solubilization of these insoluble glucans, the final residue was submitted to a partial acid hydrolysis. This work is the first report showing that the most abundant polysaccharides in BSY are polymers that contain structural features similar to cellulose, thus justifying their resistance to alkaline extractions, acid hydrolysis, and insolubility in water. © 2014 Elsevier Ltd.


Carreira P.M.,University of Lisbon | Marques J.M.,University of Lisbon | Carvalho M.R.,University of Lisbon | Nunes D.,University of Lisbon | da Silva M.A.,Unicer Bebidas SA
Environmental Earth Sciences | Year: 2014

This paper summarizes a new outlook on the conceptual model of Melgaço-Messegães CO2-rich cold (≈18 °C) mineral water systems, issuing in N of Portugal, based on their isotopic (2H, 3H, 13C, 14C and 18O) and geochemical features. Stable isotopes indicate the meteoric origin of these CO2-rich mineral waters. Based on the isotopic fractionation with the altitude, a recharge altitude between 513 up to 740 m a.s.l. was estimated, corroborating the tritium results. The lowest 3H content (0 TU) is found in the groundwater samples with the highest mineralization. The mineral waters circulation are mainly related to a granitic and granodioritic environment inducing two different groundwater types (Ca/Na-HCO3 and Na/Ca-HCO3), indicating different underground flow paths. Calcium dissolution is controlled by hydrolysis of rock-matrix silicate minerals (e.g. Ca-plagioclases) and not associated to anthropogenic sources. The shallow dilute groundwaters exhibit signatures of anthropogenic origins (e.g. NO3) and higher Na/Ca ratios. The stable isotopes together with the geochemistry provided no indication of mixing between the regional shallow cold dilute groundwater and mineral water systems. The heavy isotopic signatures identified in the δ13C data (δ13C = 4.7 ‰, performed on the total dissolved inorganic carbon (TDIC) of CO2-rich mineral waters) could be derived from a deep-seated (upper mantle) source or associated to methanogenesis (CH4 source). The negligible 14C content (≈2 pmC) determined in the TDIC of the mineral waters, corroborates the hypothesis of a mantle-derived carbon source to the mineral groundwater systems or dissolution of carbonate layers at depth. © 2013 Springer-Verlag Berlin Heidelberg.


Mata T.M.,University of Porto | Melo A.C.,University of Porto | Meireles S.,Unicer Bebidas SA | Mendes A.M.,University of Porto | And 3 more authors.
Chemical Engineering Transactions | Year: 2013

This work aims to analyze the possibility of growing microalgae Scenedesmus obliquus (S. obliquus) in a brewery wastewater as a potential candidate for biodiesel production. For this purpose S. obliquus was cultivated in a synthetic brewery wastewater at 12,000 Lux of light intensity, with a 12 h period of daily light and aeration. Under these conditions, results revealed an average lipid content of 27 % of dry-weight (dwt) biomass and average biomass and lipid concentrations of respectively, 0.90 and 0.24 g/L (of dwt biomass). The fatty acid methyl esters (FAME) transesterified from the lipids are mainly composed of saturated esters (56.4 %) among which, palmitate (C16:0) is the most significant with a relative percentage of 47.8 % (wt). With regard to the unsaturated esters, the percentage of 10.6 % (wt) obtained for linolenate (C18:3) is below the maximum limit imposed by the EN 14214:2003 standard for this ester in biodiesel. The average molecular mass of these lipids and FAME are respectively 845.2 and 283.1 g/mol. Copyright © 2013, AIDIC Servizi S.r.l.


Caetano N.S.,University of Porto | Caetano N.S.,Polytechnic Institute of Porto | Moura R.F.,University of Porto | Meireles S.,Unicer Bebidas SA | And 2 more authors.
Chemical Engineering Transactions | Year: 2013

This study performs a parametric study aiming at the optimization of the acid pretreatment step of brewer's spent grains (BSG) simultaneously with the enzymatic hydrolysis for conversion into simple sugars fermentable to bioethanol. For this purpose three acids and five enzymes were tested, by adding each two acids (HCl with H2SO4 or HCl with HNO 3) either in mixture (in one step) or sequentially (in two steps), to 25 g of dry BSG, together with varying quantities of the enzymes. Results show that when using Viscozyme L or the mixture of Cellulase and Hemicellulase by action of two acids in mixture, the total sugars conversion ranges between 20-27 wt%, in which the mixture of HCl and H2SO4 promotes a greater release of glucose plus maltose, while the mixture of HCl and HNO 3 promotes the release of higher amount of xylose and arabinose. Results also show that when Glucanex 100g and Ultraflo L are used simultaneously with the sequential addition of HCl and H2SO4, the highest total sugars conversion (54.5 wt%) is obtained using 2.30 mL of Ultraflo L and 1.67 g of Glucanex 100g. Furthermore, by increasing the amount of Glucanex 100g (from 1.67 to 2.48 g) to the same amount of Ultraflo L (2.30 mL) the total sugars conversion decreased from 54.5 wt% to 40.5 wt%. Moreover, a greater release of glucose was verified by increasing the amount of Ultraflo L (from 1.75 mL to 2.30 mL), while by increasing the amount of Glucanex 100g (from 1.67 to 2.48 g) the release of arabinose and maltose was enhanced. Also, when using Glucanex 100g and Ultraflo Lsimultaneously with the acids HCl and HNO 3, the best method to obtain high conversions of sugars is by the sequential addition of the acids, instead of in mixture. In this work, it resulted in the best conversion of BSG to simple sugars (72.1 wt%), corresponding to about 720 g of sugars per kg of dry BSG. Copyright © 2013, AIDIC Servizi S.r.l.


Martins C.,University of Aveiro | Brandao T.,Unicer Bebidas SA | Almeida A.,University of Aveiro | Rocha S.M.,University of Aveiro
Journal of Separation Science | Year: 2015

The aroma profile of beer is crucial for its quality and consumer acceptance, which is modu-lated by a network of variables. The main goal of this study was to optimize solid-phase microextraction experimental parameters (fiber coating, extraction temperature, and time), taking advantage of the comprehensive two-dimensional gas chromatography structured separation. As far as we know, it is the first time that this approach was used to the untargeted and comprehensive study of the beer volatile profile. Decarbonation is a critical sample preparation step, and two conditions were tested: static and under ultrasonic treatment, and the static condition was selected. Considering the conditions that promoted the highest extraction efficiency, the following parameters were selected: poly(dimethylsiloxane)/divinylbenzene fiber coating, at 40C, using 10 min of pre-equilibrium followed by 30 min of extraction. Around 700-800 compounds per sample were detected, corresponding to the beer volatile profile. An exploratory application was performed with commercial beers, using a set of 32 compounds with reported impact on beer aroma, in which different patterns can be observed through the structured chromatogram. In summary, the obtained results emphasize the potential of this methodology to allow an in-depth study of volatile molecular composition of beer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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