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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

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)

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)