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The global production of fossil-based plastics has reached critical levels, and their substitution with bio-based polymers is an urgent requirement. Poly(3-hydroxybutyrate) (PHB) is a biopolymer that can be produced via microbial cultivation, but efficient microorganisms and low-cost substrates are required. Halomonas boliviensis LC1, a moderately halophilic bacterium, is an effective PHB producer, and hydrolysates of the residual stalks of quinoa (Chenopodium quinoa Willd.) can be considered a cheap source of sugars for microbial fermentation processes in quinoa-producing countries. In this study, H. boliviensis LC1 was adapted to a cellulosic hydrolysate of quinoa stalks obtained via acid-catalyzed hydrothermal pretreatment and enzymatic saccharification. The adapted strain was cultivated in hydrolysates and synthetic media, each of them with two different initial concentrations of glucose. Cell growth, glucose consumption, and PHB formation during cultivation were assessed. The cultivation results showed an initial lag in microbial growth and glucose consumption in the quinoa hydrolysates compared to cultivation in synthetic medium, but after 33 h, the values were comparable for all media. Cultivation in hydrolysates with an initial glucose concentration of 15 g/L resulted in a higher glucose consumption rate (0.15 g/(L h) vs. 0.14 g/(L h)) and volumetric productivity of PHB (14.02 mg/(L h) vs. 10.89 mg/(L h)) than cultivation in hydrolysates with 20 g/L as the initial glucose concentration. During most of the cultivation time, the PHB yield on initial glucose was higher for cultivation in synthetic medium than in hydrolysates. The produced PHBs were characterized using advanced analytical techniques, such as high-performance size-exclusion chromatography (HPSEC), Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). HPSEC revealed that the molecular weight of PHB produced in the cellulosic hydrolysate was lower than that of PHB produced in synthetic medium. TGA showed higher thermal stability for PHB produced in synthetic medium than for that produced in the hydrolysate. The results of the other characterization techniques displayed comparable features for both PHB samples. The presented results show the feasibility of producing PHB from quinoa stalks with H. boliviensis.

Auto-catalyzed hydrothermal pretreatment (A-HTP) and sulfuric-acid-catalyzed hydrothermal pretreatment (SA-HTP) were applied to quinoa stalks in order to reduce their recalcitrance towards enzymatic saccharification. Prior to pretreatment, quinoa stalks were extracted with either water or a 50:50 (v/v) ethanol–water mixture for removing saponins. Extraction with water or aqueous ethanol, respectively, led to removal of 52 and 75% (w/w) of the saponins contained in the raw material. Preliminary extraction of quinoa stalks allowed for a lower overall severity during pretreatment, and it led to an increase of glucan recovery in the pretreated solids (above 90%) compared with that of non-extracted quinoa stalks (73–74%). Furthermore, preliminary extraction resulted in enhanced hydrolysis of hemicelluloses and lower by-product formation during pretreatment. The enhancement of hemicelluloses hydrolysis by pre-extraction was more noticeable for SA-HTP than for A-HTP. As a result of the pretreatment, glucan susceptibility towards enzymatic hydrolysis was remarkably improved, and the overall conversion values were higher for the pre-extracted materials (up to 83%) than for the non-extracted ones (64–69%). Higher overall conversion was achieved for the aqueous ethanol-extracted quinoa stalks (72–83%) than for the water-extracted material (65–74%).

Candida maltosa was cultivated in the liquid phase of residual brewing yeast, a major brewery residue, to produce biomass and biofilm. Using response surface methodology, the effect of two variables at two different levels was investigated. The independent variables were agitation speed (at 100 and 200 rpm), and aeration (at 1 and 3 L min−1). Aeration was identified to be important for the production of both biomass and biofilm, while agitation was the only factor significantly affecting biofilm production. The maximal production of biofilm (2.33 g L−1) was achieved for agitation of 200 rpm and aeration of 1 L min−1, while the maximum for biomass (16.97 g L−1) was reached for 100 rpm agitation and 3 L min−1 air flow. A logistic model applied to predict the growth of C. maltosa in the exponential phase and the biofilm production, showed a high degree of agreement between the prediction and the actual biomass measured experimentally. The produced biofilms were further characterized using Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). FTIR allowed the identification of methyl, carbonyl ester and sulfate groups, and revealed the presence of uronic acid moieties and glycosidic bonds. Water-retention ability up to relatively high temperatures was revealed by TGA, and that makes the produced biofilm suitable for production of hydrogels. SEM also gave indications on the hydrogel-forming potential of the biofilm. This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0

The halotolerant bacterial strain BU-4, isolated from a hypersaline environment, was identified as an exopolysaccharide (EPS) producer. Pretreatment liquids of steam-exploded quinoa stalks and enzymatic hydrolysates of Curupaú sawdust were evaluated as carbon sources for EPS production with the BU-4 strain, and the produced EPS was characterized using FTIR, TGA, and SEM. Cultivation was performed at 30 °C for 48 h, and the cells were separated from the culture broth by centrifugation. EPS was isolated from the cell pellets by ethanol precipitation, and purified by trichloroacetic acid treatment, followed by centrifugation, dialysis, and freeze-drying. EPS production from quinoa stalks- and Curupaú sawdust-based substrates was 2.73 and 0.89 g L−1, respectively, while 2.34 g L−1 was produced when cultivation was performed on glucose. FTIR analysis of the EPS revealed signals typical for polysaccharides, as well as ester carbonyl groups and sulfate groups. High thermal stability, water retention capacity and gel-forming ability were inferred from SEM and TGA. The capability of the halotolerant isolate for producing EPS from pretreatment liquids and hydrolysates was demonstrated, and characterization of the EPS revealed their broad application potential. The study shows a way for producing value-added products from waste materials using a bacterium from a unique Bolivian ecosystem.

Daniel E Osorio-Macías,1,2 Pamela Vásquez,3 Cristhian Carrasco,3 Bjorn Bergenstahl,1 J Mauricio Peñarrieta2 1Department of Food Technology, Faculty of Engineering LTH, Lund University, Lund, Sweden; 2School of Chemistry, Faculty of Pure and Natural Sciences, 3Institute of Research and Development of Chemical Processes, Department of Chemical Engineering, Faculty of Engineering, Universidad Mayor de San Andrés (UMSA), La Paz, Bolivia Abstract: Wine is an important beverage with a long tradition, and its moderate consumption may be considered beneficial for human health. Although there are many studies regarding phenolic compounds in wines, there is a lack of information about antioxidants and phenolic content in South American wines. In this study, 35 South American red wines from four different countries, vintages 2004–2013, purchased at retail stores in La Paz, Bolivia, were studied. Resveratrol content, total antioxidant capacity (TAC) by the 2,2′-azino-bis(3-ethylbenzotiazoline-6-sulfonic acid) (ABTS) and ferric-reducing antioxidant power (FRAP) methods, total phenolic content (TPH), total flavonoids (TF), and main saccharides were assessed using the well-established spectrophotometric and high-performance liquid chromatography methods. The results ranged from 4 to 24 mmol/L for TAC determined by ABTS method and 14 to 43 mmol/L for TAC determined by FRAP method, 1600 to 3500 mg gallic acid equivalents/L for TPH, and 2 to 6 mmol catechin equivalents /L for TF. The resveratrol content ranged from 0.1 to 8 mg/L. Saccharides, glucose, and fructose content ranged from 0.4 to 10 g/L, 1.4 to 8.6 g/L, and 0.2 to 12 g/L, respectively. There was a high correlation among the different methods. The results showed that some wines growing at high altitude (>1500 meters above the sea level) have higher amounts of TAC and phenolic content, including resveratrol, while non-varietal wines showed the lowest values. It was also observed that the saccharose content in some wines was surprisingly high, suggesting saccharose dosing after fermentation. Keywords: ABTS, FRAP, high altitude, HPLC, PCA, Bolivia

Byproducts from quinoa are not yet well explored sources of hemicellulose or products thereof. In this work, xylan from milled quinoa stalks was retrieved to 66% recovery by akaline extraction using 0.5 M NaOH at 80 °C, followed by ethanol precipitation. The isolated polymer eluted as a single peak in size-exclusion chromatography with a molecular weight of700 kDa. Analysis by Fourier transform infrared spectroscopy and nuclear magnetic resonance (NMR) combined with acid hydrolysis to monomers showed that the polymer was built of a backbone of β(1 → 4)-linked xylose residues that were substituted by 4-O-methylglucuronic acids, arabinose, and galactose in an approximate molar ratio of 114:23:5:1. NMR analysis also indicated the presence of α(1 → 5)-linked arabinose substituents in dimeric or oligomeric forms. The main xylooligosaccharides (XOs) produced after hydrolysis of the extracted glucuronoarabinoxylan polymer by thermostable glycoside hydrolases (GHs) from families 10 and 11 were xylobiose and xylotriose, followed by peaks of putative substituted XOs. Quantification of the unsubstituted XOs using standards showed that the highest yield from the soluble glucuronoarabinoxylan fraction was 1.26 g/100 g of xylan fraction, only slightly higher than the yield (1.00 g/100 g of xylan fraction) from the insoluble fraction (p0.05). No difference in yield was found between reactions in buffer or water (p0.05). This study shows that quinoa stalks represent a novel source of glucuronoarabinoxylan, with a substituent structure that allowed for limited production of XOs by GH10 or GH11 enzymes.

BACKGROUNDQuinoa is a pseudo-cereal grown predominantly in South America. The quinoa stalks are lignocellulosic residues, which have a limited use today. The objective of the current study was to assess the potential of this material as a source of monosaccharides for fermentation purposes by means of steam pretreatment giving sugars from the hemicellulose part, and enzymatic hydrolysis of the solid fraction obtained. SO2 catalysed steam pretreatment was carried out with a holding time of 5min at temperatures between 180 and 220 degrees C. The pretreatment was carried out at two different scales, a small reactor of size 0.5L and a somewhat larger reactor of size 10L, to allow comparison of scale effects in the pretreatment. RESULTSThe highest xylose yield in the liquid phase, obtained after pretreatment at 210 degrees C, was 80%. In the smaller scale unit, longer residence times were needed. The enzymatic hydrolysis, at an enzyme loading of 15 FPU g(-1) glucan and a WIS loading of 2%, resulted in a glucose yield of 70% based on the original glucan. The overall sugar yield, including the xylan hydrolysed in the enzymatic treatment, at dilute conditions was 75%. CONCLUSIONSSO2 catalysed pretreatment of quinoa straw followed by enzymatic hydrolysis gave a relatively good sugar yield. However, the yield obtained was somewhat lower than previously reported for similar materials, such as wheat straw and sugarcane bagasse, steam pretreated with SO2. (c) 2013 Society of Chemical Industry (Less)

Paja Brava is a native South American grass with a high carbohydrate content. In the current work, the potential of using this feedstock for ethanol production using a simultaneous saccharification and fermentation (SSF) process with the xylose-fermenting yeast Pichia stipitis (Scheffersomyces stipitis) CBS6054 was investigated. The straw material was subjected to SO2 catalyzed steam pretreatment at 200°C and 5 min residence time, which resulted in a solubilization of pentose sugars (mainly xylose) of 64% with only minor amounts of degradation products. The obtained material, including the pretreatment liquid, was subsequently hydrolyzed and fermented in an SSF process at microaerobic conditions using either a batch or a fed-batch process at a total water-insoluble solids loading of 10%. Overall yields of ethanol based on all available sugars of 0.24 g/g and 0.27 g/g were obtained for batch and fed-batch mode of operation, respectively. The higher yield in the fed-batch process coincided with a higher degree of conversion of the sugars in the liquid medium, in particular of arabinose, for which the conversion was doubled (from 48% to 97%).

The price of raw material, energy demand in the pretreatment step, and enzyme usage rate are the major cost factors in the process of converting biomass to bioethanol. Unwashed furfural residues (FRs) possess great potential for application in bioethanol production. Surfactant addition is an effective method to enhance the fermentation rate. In this study, unwashed FRs were used directly as raw materials to produce bioethanol. Tea-seed cake (TSC), tea seed residues that contained protein and saponin, was added in the simultaneous saccharification and fermentation (SSF) process. The effect of TSC dosage on SSF was compared. TSC was added at the dosage of 10 g/L, which resulted in a final ethanol yield of 87.2%. However, a high concentration of TSC could induce cytotoxicity in yeast. The surface tension (approximately 33.92 mM/m) at SSF using TSC-medium was much lower than that of other fermentation systems (about 64.67 mN/m). Further contact angle testing showed that TSC-medium (21.7°) had better wetting capacity than FRs (45.6°). This study provided a proposed process strategy that SSF with the addition of TSC could be a minimum consumption of chemicals and enzymes for future cellulosic ethanol production process.

Sugarcane bagasse is a lignocellulosic residue obtained from sugarcane milling, and a potentially interesting raw material that can be used for fuel ethanol production. In the present study, bagasse was steam pretreated at temperatures between 180 and 205 ◦C, with holding times of 5–10 min using SO2 as a catalyst to determine conditions that provide a good recovery of pentoses and a suitable material for enzymatic hydrolysis. Pretreatment conducted at 190 ◦C for 5 min gave a pentose yield of 57%, with only minor amounts of degradation compounds formed. Commercial cellulolytic enzymes were used to hydrolyze the obtained fiber fractions after pretreatment at different water-insoluble solid contents (2%, 5% and 8% WIS). The overall highest sugar yield achieved from bagasse was 87% at 2% WIS. Fermentation tests were made on both the pentose-rich hemicellulose hydrolysate obtained from the pretreatment, and the enzymatic hydrolysates obtained from the fiber fractions using the xylose-fermenting strain of Saccharomyces cerevisiae TMB3400, as well as the natural xylose-utilizing yeast Pichia stipitis CBS 6054. The pretreatment hydrolysates produced at 2% WIS as well as the enzymatic hydrolysates showed a complete glucose fermentability indicating a low toxicity to the yeasts. The best xylose conversion (more than 60%) was achieved by the strain TMB3400 at 2% WIS. (Less)

A pentose-rich hydrolysate fraction obtained by extraction of steam-pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO2 (w/w) at 190 ◦C for 5min)was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, themain dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5-O-(trans-feruloyl)-L-Arabinofuranose and 5-O-(trans-coumaroyl)-L-Arabinofuranose, together with p-coumaric acid and small amounts of more common free phenolics such as p-hydroxybenzaldehyde, p-hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed-phase high-performance liquid chromatography. The findings show that SO2 steam explosion opened up new degradation pathways during lignin degradation. (Less)

Pretreatment, enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) of the South American straw material Paja Brava were investigated. Suitable process conditions for an SO(2)-catalyzed steam pretreatment of the material were determined and assessed by enzymatic digestibility of obtained fiber slurries for 72h at a water insoluble solids (WIS) content of 2%. The best pretreatment conditions obtained (200°C, 5min holding time and 2.5% SO(2)) gave an overall glucose yield following enzymatic hydrolysis of more than 90%, and a xylose yield of about 70%. Simultaneous saccharification and co-fermentation of glucose and xylose (SSCF) of the pretreated material using the xylose-fermenting strain Saccharomyces cerevisiae TMB3400 was examined at WIS contents between 5% and 10%. In agreement with previous studies on other materials, the overall ethanol yield and also the xylose conversion decreased somewhat with increasing WIS content in the SSCF. In batch SSCF, the xylose conversion obtained was almost 100% at 5% WIS content, but decreased to 69% at 10% WIS. The highest ethanol concentration obtained for a WIS content of 10% was about 40g/L, corresponding to a yield of 0.41g/g in a fed-batch SSCF. The Paja Brava material has previously been found difficult to hydrolyze in a dilute-acid process. However, the SSCF results obtained here show that similar sugar yields and fermentation performance can be expected from Paja Brava as from materials such as wheat straw, corn stover or sugarcane bagasse. (Less)