Alcohols In Yields Research Articles

Carbon-Supported KCoMoS2 for Alcohol Synthesis from Synthesis Gas

KCoMoS2 was supported on various carbon support materials to study the support effect on synthesis gas conversion. Next to two activated carbons with high micropore volume, a traditional alumina (γ-Al2O3) support and its carbon coated form (CCA) were studied for comparison. Coating alumina with carbon increases the selectivity to alcohols, but the AC-supported catalysts show even higher alcohol selectivities and yields, especially at higher temperatures where the conversions over the AC-supported catalysts increase more than those over the γ-Al2O3-based catalysts. Increasing acidity leads to decreased CO conversion yield of alcohols. The two activated-carbon-supported catalysts give the highest yield of ethanol at the highest conversion studied, which seems to be due to increased KCoMoS2 stacking and possibly to the presence of micropores and low amount of mesopores.

Biotechnological Approaches to Lowering the Ethanol Yield during Wine Fermentation.

One of the most prominent consequences of global climate warming for the wine industry is a clear increase of the sugar content in grapes, and thus the alcohol level in wines. Among the several approaches to address this important issue, this review focuses on biotechnological solutions, mostly relying on the selection and improvement of wine yeast strains for reduced ethanol yields. Other possibilities are also presented. Researchers are resorting to both S. cerevisiae and alternative wine yeast species for the lowering of alcohol yields. In addition to the use of selected strains under more or less standard fermentation conditions, aerobic fermentation is increasingly being explored for this purpose. Genetic improvement is also playing a role in the development of biotechnological tools to counter the increase in the wine alcohol levels. The use of recombinant wine yeasts is restricted to research, but its contribution to the advancement of the field is still relevant. Furthermore, genetic improvement by non-GMO approaches is providing some interesting results, and will probably result in the development of commercial yeast strains with a lower alcohol yield in the near future. The optimization of fermentation processes using natural isolates is, anyway, the most probable source of advancement in the short term for the production of wines with lower alcohol contents.

Electrocatalytic Hydrogenation of unsaturated Aldehydes – Influence of External Electric Potential and Promotor Species on Carbonyl Group Activation

The production of chemicals and fuels via transformation of biomass-derived feedstock requires the hydrodeoxygenation of oxygenated intermediates (e.g. carboxylic acids, aldehydes or phenolic compounds).[1] Usually, this step is done by thermal hydrogenation at elevated temperatures and high pressures, in which the reacting hydrogen is still supplied from reforming of non-sustainable fossil resources. These drawbacks make the hydrogenation of oxygen-containing intermediates the most energy- and capital-intensive step during the biomass upgrading process.[2] Electrocatalytic hydrogenation, in contrary, is a promising, sustainable technology for the ambient reduction of organic molecules. The required hydrogen is produced in situ from reduction of hydronium ions or electrolysis of water that is driven by renewable resources.[3] Especially, the selective hydrogenation of α,β-unsaturated aldehydes towards their corresponding unsaturated alcohols has proven difficult in the past, even under thermal conditions (ΔpH2, ΔT).[4] When using common hydrogenation catalysts that are based on noble metals, e.g. Pd, Rh, Ru, hydrogenation of the double bond towards saturated aldehydes is by far more likely than conversion of the carbonyl moiety.[5] Therefore, researchers have put lots of efforts in developing new catalysts that are capable of selectively converting α,β-unsaturated aldehydes towards unsaturated alcohols under thermal conditions. The addition of promotors specifically activating the CO-bond, e.g. metal oxide species, oxophilic metals, is one approach that has proven beneficial in tuning the reaction selectivity.[6] Another approach towards selective hydrogenation of the carbonyl group is the repulsion of the double bond away from the catalyst surface either electrostatically via changing the charge density on the catalyst surface or sterically via particle size effects.[7] The present study investigates the electrocatalytic hydrogenation of trans-pent-2-en-1-al and trans-cinnamaldehyde on transition metal catalysts supported on carbon nanotubes in aqueous phase (Scheme 1). The influence of different noble metals as well as promotor species on the reaction selectivity, especially concerning the formation of α,β-unsaturated alcohols, is analyzed. Furthermore, the impact of an external electric potential on product distribution and reaction kinetics is evaluated. The effect of different metals, promotors as well as the presence of an external electric potential on the kinetic data shall be related to adsorption measurements of organic species on the catalyst surface both via cyclic voltammetry (CV) and UV/VIS-spectroscopy.In a recent study, we have shown that adding phenol to an aqueous electrolyte gradually blocks sites for H adsorption and hence, diminishes the Hupd peaks in CV curves recorded on Pt.[8] Now, we are seeking to correlate these findings with adsorption isotherms measured via UV/VIS absorption spectroscopy in order to answer the question whether different moieties, e.g. double bond, carbonyl group, lead to changes in the adsorption and activation of organic molecules on the electrode surface that can explain the differences in reaction kinetics and product distribution. Furthermore, we want to shed light on the influence of increasing the negative charge density on the electrode during ECH on electrostatic repulsion of electron-rich moieties away from the catalyst surface. First results on the hydrogenation of trans-pent-2-en-1-al showed that in case of ECH the yield of alcohol was increased by two orders of magnitude compared to thermal hydrogenation.[1] Y. Song, O. Y. Gutiérrez, J. Herranz, J. A. Lercher, Applied Catalysis B: Environmental 2016, 182, 236-246.[2] Y. Song, U. Sanyal, D. Pangotra, J. D. Holladay, D. M. Camaioni, O. Y. Gutiérrez, J. A. Lercher, Journal of Catalysis 2018, 359, 68-75.[3] U. Sanyal, J. Lopez-Ruiz, A. B. Padmaperuma, J. D. Holladay, O. Y. Gutiérrez, Organic Process Research & Development 2018, 22, 1590-1598.[4] a) P. Gallezot, D. Richard, Catalysis Reviews 1998, 40, 81-126; b) P. Claus, Topics in Catalysis 1998, 5, 51-62.[5] a) X. Lan, T. Wang, ACS Catalysis 2020, 10, 2764-2790; b) C. Louis, L. Delannoy, in Advances in Catalysis, Vol. 64 (Ed.: C. Song), Academic Press, 2019, pp. 1-88.[6] a) M. Tamura, K. Tokonami, Y. Nakagawa, K. Tomishige, ACS Catalysis 2016, 6, 3600-3609; b) Y. Dai, X. Gao, X. Chu, C. Jiang, Y. Yao, Z. Guo, C. Zhou, C. Wang, H. Wang, Y. Yang, Journal of Catalysis 2018, 364, 192-203; c) N. Mahata, F. Gonçalves, M. F. R. Pereira, J. L. Figueiredo, Applied Catalysis A: General 2008, 339, 159-168.[7] E. Bailón-García, F. J. Maldonado-Hódar, A. F. Pérez-Cadenas, F. Carrasco-Marín, Catalysts 2013, 3.[8] N. Singh, U. Sanyal, J. L. Fulton, O. Y. Gutiérrez, J. A. Lercher, C. T. Campbell, ACS Catalysis 2019. Figure 1

UV‐induced oxygenation of toluene enhanced by Co (acac)2/9‐mesityl‐10‐methylacridinium ion/N‐hydroxyphthalimide tandem

AbstractThe effect of near‐UV irradiation on the oxygenation of toluene dissolved in MeCN was studied in a stainless‐steel reactor upon O2 bubbling at 80°C and 100°C and 10 atm using Co (acac)2 and 9‐mesityl‐2,7,10‐trimethylacridinium perchlorate (Me2Acr+–Mes ClO4−) as the catalyst and photocatalyst, respectively. In the absence of the process mediator N‐hydroxyphthalimide (NHPI), the rate of PhCH3 oxidation was extremely low, leading to trace amounts of the products formed. The presence of NHPI and the irradiation with UV light enhanced the substrate oxygenation and benzyl alcohol, benzaldehyde, and benzoic acid yield substantially by three to four times. The relative content of the last product was lowest at the beginning of the process as well as in light‐excited oxygenation. In this report, we highlight the mechanism of catalyst, photocatalyst, and mediator combined effect on product yield and composition.

Characterization of major volatile compounds in whey spirits produced by different distillation stages of fermented lactose-supplemented whey

This research aimed to advance the understanding of acceptable sensory qualities of potable whey-based spirit from nonsupplemented, mid-supplemented, and high-supplemented whey samples by analyzing major volatile compounds during different stages of distillation (head, heart, and tail). The results demonstrated that commercial Saccharomyces cerevisiae strain in lactase-hydrolyzed whey showed rapid and complete sugar hydrolysis and efficient ethanol production in 24, 30, and 36 h on average, producing up to 29.5, 42.1, and 56.4 g/L of ethanol, respectively. The variations in titratable acidity, specific gravity, pH value, residual protein, sugar content, and alcohol yield were investigated during the fermentation. The total amount of volatile compound concentrations significantly decreased from the head (2,087-2,549 mg/L) to the tail whey spirits (890-1,407 mg/L). In the whey spirit, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-1-propanol, 1-propanol, acetaldehyde, and ethyl acetate were the most prevalent dominant compounds, accounting for the largest proportion of total volatile compounds. The volatile compounds detected were far below the acceptable legal limit. The results suggest that high sensory qualities of potable whey-based spirits can be produced by fermentation of lactose-supplemented whey with S. cerevisiae cells.

Optimization of Fermentation Conditions for Production of Hungarian Sour Cherry Spirit Using Response Surface Methodology

Pálinka is a traditional fruit spirit and a kind of gastronomic heritage in Hungary. In Pálinka production, fermentation is one of the most important processes affecting the quality and yield of spirits. Based on single-factor and three-factor influence level tests by following the Plackett–Burman design, the fermentation process from sour cherry juice concentrate and Saccharomyces cerevisiae by using Response Surface Methodology (RSM) coupled with the central composite rotatable design was investigated to optimize fermentation conditions through three variables in a defined range of temperature (15–25 °C), pH (2.75–3.75), and total soluble solid (18–30 °Brix). After eight fermentation days, production yields of alcohol and volatile compounds were a maximum of 9.02% v/v and 337.37 mg/L at an optimized temperature of 24.71 °C, pH of 3.25, and total soluble solid of 22.49 °Brix. The GC-FID analysis results showed 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, and ethyl acetate were considered the major aroma compound in the cherry spirits. These results provided important information in serving the basic to develop standard fruit spirits production from sour cherry.

Design of efficient ZnO/ZrO2 modified CuCoAl catalysts for boosting higher alcohol synthesis in syngas conversion

Selective synthesis of higher alcohols from syngas conversion is highly desirable, but still very challenging. Here, focusing on the commonly used CuCoAl (CCA) catalyst, we attempted to reconcile the capability of the non-dissociation of CO species and the activation of H2 through adding ZnO modified ZrO2 composite into the catalyst for the promotion of higher alcohols synthesis. Under the guidance of such concept, a series of CCA|ZnO/ZrO2 (m: n) modified catalysts (m: n, represent the mass ratio of ZnO to ZrO2) were prepared by mortar-mixing CuCoAl and ZnO/ZrO2 components (2/1 wt ratio). It was found that the CCA|ZnO/ZrO2 (4:1) catalyst showed a highest total alcohols (ROH) selectivity of 42.6 wt% with excellent C2+OH/ROH fraction of 83.7% among the investigated catalysts. The surface [H*]/[C*] ratio of CCA|ZnO/ZrO2 catalysts, as revealed by (CO+H2)-TPD-MS results, increased with the rise of ZnO/ZrO2 ratio. Moreover, the CCA|ZnO/ZrO2 (4:1) catalyst with moderate [H*]/[C*] ratio could acquire the highest ROH selectivity and best space time yield of total alcohols (STYROH) due to that the balance of relative amount of CO*, CHx* and H* species provided the more probability of CnHx*-CO* coupling reaction for higher alcohols synthesis, rather than the hydrogenation reaction of CHx* or CnHx* species and water gas shift reaction.

Effect of ammonium acetate on alcohol fermentation in cassava-alcohol fermentation process

The cassava-alcohol fermentation process employing cassava requires nitrogen source to maximize yields by a commercial strain of S. cerevisiae TG1348. In this study, a factorial experimental design was used to assess a suitable nitrogen source for growth and fermentative performance of S. cerevisiae in cassava-ethanol fermentation. The alcohol fermentation time was about 39 h for urea and ammonium acetate, which was 48 h for ammonium chloride and ammonium sulphate. The fermentation time was reduced by 19 % when using urea and ammonium acetate as nitrogen source. Ammonium acetate leaded to the highest alcohol yield, which was 4% higher than for ammonium sulphate. In addition, byproduct formation differed obviously between the nitrogen sources. The glycerol yields were similar for urea, ammonium sulphate and ammonium chloride but were 24 % lower for ammonium acetate. However, glycerol yield for ammonium carbonate was higher than for other nitrogen sources. Clearly, in batch cultures the ammonium acetate not only increased ethanol generation, but also decreased glycerol generation. In order to understand why ammonium acetate promotes alcohol fermentation, acetic acid was added to different nitrogen sources. The weight loss effect of ammonium sulphate adding acetic acid and ammonium acetate as nitrogen source was the same. The fermentation time was shortened by adding acetic acid. And pH was increased by addition of acetic acid when ammonium sulfate and urea were used as nitrogen sources. The results showed that the acetate root plays an important role in ammonium acetate. The results of this study could facilitate the development of new strategies to control fermentation performance.

Effect of baking technique for rice wine production and the characteristics of baked rice wine.

Driven by the requirement to reduce the emission of wastewater in the brewing process, it is necessary to improve and innovate the fermentation technology of Chinese rice wine. In this study, the baking technique used to brew rice wine was explored. Rice wine was brewed based on baked glutinous rice undergoing different high-temperature stages, designated as baked rice wine (BRW1, BRW2 and BRW3). X-ray diffraction and Fourier transform infrared analysis revealed that baking treatment under 110 °C 0.5 h + 170 °C 30 min relatively changed the crystal properties and short-range molecular order of starch. Compared with the traditional rice wine (RW) from steamed rice, the alcohol content in BRWs was nearly twice that of RW, especially in BRW3. The contents of protein, ascorbic acid and total phenols in BRWs were significantly higher than that in RW. Besides, BRWs presented more abundance in the contents of volatile compounds, free amino acids and certain organic acids, including volatile esters and alcohols and 17 amino acids, which would give rice wine a pleasant aroma and a more comprehensive taste. Furthermore, analysis of the antioxidant capacity indicated a functional difference between RW and BRWs. It was feasible to produce rice wine using baked rice. The baking method allowed for several advantages, including the improvement of alcohol yield, fermentation efficiency, new typicality and stronger antioxidant capacity. This work is expected to provide a foundation for related research. © 2021 Society of Chemical Industry.

Simultaneously deleting ADH2 and THI3 genes of Saccharomyces cerevisiae for reducing the yield of acetaldehyde and fusel alcohols.

The reduced yields of acetaldehyde and fusel alcohols through fermentation by Saccharomyces cerevisiae is of significance for the improvement of the flavor and health of alcoholic beverages. In this study, the ADH2 (encode alcohol dehydrogenase) and THI3 (encode decarboxylase) genes of the industrial diploid strain S. cerevisiae XF1 were deleted. Results showed that single-gene-deletion mutants by separate gene deletion of ADH2 or THI3 led to a reduced production of the acetaldehyde or fusel alcohols, respectively. In the meantime, the double-gene-deletion mutant S. cerevisiae XF1-AT was constructed by deleting the ADH2 and THI3 simultaneously. An equivalent level of the ethanol production by the S. cerevisiae XF1-AT could be achieved but with the yields of acetaldehyde, isoamyl alcohol and iso-butanol reduced by 42.09%, 15.65% and 20.16%, respectively. In addition, there was no interaction between the ADH2 deletion and THI3 deletion in reducing the production of acetaldehyde and fusel alcohols. The engineered S. cerevisiae XF1-AT provided a new strategy to alcoholic beverages brewing industry for reducing the production of acetaldehyde as well as the fusel alcohols.

Optimization and Kinetic Modeling of Honey Fermentation for Laboratory and Pilot-Scale Mead Production

Honey is usually employed for the elaboration of mead, an alcoholic beverage obtained through fermentation with yeast. However, its production in many places is incipient and still has such drawbacks as long process times, undesired fermentation, and sensory quality problems. In this research, a three-level factorial design was used to evaluate the effect of the initial honey monosaccharide concentration (glucose and fructose) and yeast assimilable nitrogen content on the alcoholic fermentation yield at a laboratory scale. Fermentation tests were conducted at 25 °C for 20 days using Saccharomyces cerevisiae subsp. bayanus and bee-pollen as a nutrient source. Residual sugars, assimilable nitrogen, glycerol, ethanol, and ethanol/sugar yield were calculated. Optimization by Response Surface Methodology showed that maximal predicted yield (46.1%) was obtained when sugar concentration and yeast assimilable nitrogen levels were 22% and 123 mg/L, respectively. Once the best conditions were determined, pilot-scale fermentations were performed, and then, logistic and Gompertz models were adjusted. The results were consistent with the results found on the laboratory scale, which suggest fermentable sugars and yeast assimilable nitrogen content can vary between 21 to 25% and 120 to 150 mg/L, respectively, to obtain a physical, chemical, and sensory acceptable beverage. Supplemental data for this article is available online at at.

Efficient Synthesis of Sugar Alcohols over a Synergistic and Sustainable Catalyst

Main observation and conclusionA series of catalysts were prepared for sugar alcohols production to overcome the deficiencies of the previous reported catalysts, such as low yield of sugar alcohols, single function, instability, and controversial role of active sites. The role of each metal and their synergistic‐cooperation was discussed in detail with a combination of conditional experiments and characterizations. The results indicated that bifunctional Ni6.66Fe1Al1.55 catalyst has unique structure with superparamagnetism and excellent activity. The (111) and (200) planes of metallic Ni are the hydrogenation active phases and preferentially exposed on Ni‐Al‐Ox spinel. The desired arabitol or mannitol was obtained by tuning the ratio of Brønsted and Lewis acid sites. The recycling tests indicated that the unique structure of the prepared Ni‐based catalyst can suppress leaching and poisoning, which has high textural stability and activity.

Improving the Utilization of Isomaltose and Panose by Lager Yeast Saccharomyces pastorianus

Approximately 25% of all carbohydrates in industrial worts are poorly, if at all, fermented by brewing yeast. This includes dextrins, β-glucans, arabinose, xylose, disaccharides such as isomaltose, nigerose, kojibiose, and trisaccharides such as panose and isopanose. As the efficient utilization of carbohydrates during the wort’s fermentation impacts the alcohol yield and the organoleptic traits of the product, developing brewing strains with enhanced abilities to ferment subsets of these sugars is highly desirable. In this study, we developed Saccharomyces pastorianus laboratory yeast strains with a superior capacity to grow on isomaltose and panose. First, we designed a plasmid toolbox for the stable integration of genes into lager strains. Next, we used the toolbox to elevate the levels of the α-glucoside transporter Agt1 and the major isomaltase Ima1. This was achieved by integrating synthetic AGT1 and IMA1 genes under the control of strong constitutive promoters into defined genomic sites. As a result, strains carrying both genes showed a superior capacity to grow on panose and isomaltose, indicating that Ima1 and Agt1 act in synergy to consume these sugars. Our study suggests that non-GMO strategies aiming to develop strains with improved isomaltose and panose utilization could include identifying strains that overexpress AGT1 and IMA1.

Effect of iron on ZrO2-based catalysts for direct synthesis of isobutanol from syngas

Direct conversion of syngas (H2/CO) to isobutanol is a promising route for clean coal combustion. However, there are still many challenges in the catalyst system of isobutanol synthesis, such as low CO conversion and alcohol yield. In this paper, we introduce Fe component with strong chain increasing ability into CuZrO2-based catalyst to modify it, which significantly improved the CO conversion and total alcohol space–time yield (STY). The results of the characterization showed that the introduction of Fe increased the specific surface area of the catalyst, promoted the dispersion of components, and enhanced the interaction between Cu and ZrO2. The KFe0.013CuZrO2 catalyst surface possessed the most amount of weakly adsorbed CO and basic sites, which were conductive for C2 intermediate formation and aldol-condensation reaction respectively. Thus, it exhibited a CO conversion of 48.6%, a selectivity of 21.8(wt)% and a space time yield (STY) of 202 g·Lcat−1·h−1 total alcohols.

USING BIOPREPARATIONS TO OPTIMIZE POTATO NUTRITION IN THE SOUTHERN STEPPE OF UKRAINE

Potatoes in Ukraine belong to the main food crops, it is used for food throughout the year for the high nutritional quality of tubers. However, despite the significant demand for potatoes, its yield remains low and there is a need to improve the technological methods of the crop growing, which contribute to both increasing the production of tubers and improving the main indicators of their quality. The article presents the results of research conducted in 2017-2019 years on improving the nutrition of potato varieties by drip irrigation on southern Chernozem. It was determined the positive influence of mineral fertilizers and foliar nutrition on the background of application of modern biopreparations in the main periods of vegetation of plants on the level of yield of tubers and their quality. It was found that the yield of tubers under the influence of nutrition in the potato variety Minerva grew in the range of 3.0 up to 13.2 t/ha, and in the Riviera variety the yield of tuber grew from 3.2 up to 12.6 t/ha, or respectively by 18.0-79.0% and 16.4-64.6% depending on the variant. In addition to the increase in the yield level, the main properties of tubers were improved by optimizing nutrition - they increased the content of dry substance, vitamin C and starch, the conditional yield of starch per unit area increased, and, if the tubers were processed, the yield of alcohol and bioethanol increased.

Технологічні аспекти виробництва спиртових дистилятів з нетрадиційної цукровмісної сировини

An actual problem of the alcohol industry development is the expansion of the raw material base through the use of new, cheaper types of carbohydrate sources. Recently, glucose-fructose syrup has been of increasing interest to producers of ethanol. Among the producers of craft drinks, in particular rum-based drinks, cane molasses is in increasing demand. The article presents the technological aspects of the fermentation process of nonconventional sugar-containing raw materials on the example of glucose-fructose syrup and cane molasses in ethanol by different yeast strains. It is determined that glucose-fructose syrup and cane molasses are raw materials depleted of nitrogen, phosphorus and growth substances necessary for the yeast activity. To improve the technological properties of raw materials in the molasses, nitrogen, phosphorus nutrition and corn extract as a growth substance shall be added to a mash. Glucose-fructose syrup is of pH 3.68 and of acidity 0.12, which negatively affects the fermentation. It is established that in order to create optimal living conditions for yeast, it is necessary to add substances to the glucose-fructose syrup that will contribute to the safety of development and prevent the pH 3.5. It was determined that the alcohol yield from 1 ton of glucose-fructose syrup is 31.0 dal, from 1 ton of cane molasses is 24.0 dal on the yeast 46ED and 22 dal on the TegaYeast without the use of growth substances and vitamins necessary for the reproduction of yeast biomass. Under conditions of improving the technological properties of the mash from the glucose-fructose syrup and cane molasses by adding biologically active substances promoting the synthesis of yeast biomass, the ethanol content in the fermented mashes increases up to 11.9 12% vol.

In Situ Hybridizing Cu3(BTC)2 and Titania to Attain a High‐Performance Copper Catalyst: Dual‐Functional Role of Metal‐Support Interaction on the Activity and Selectivity

AbstractProduction of value‐added chemicals sourced from biomass platform molecules has tremendous significance for sustainable chemical engineering. Herein, we reported a successful fabrication of a highly dispersed copper nanoparticles catalyst, CuO#TiO2, via a facile route of in situ homogeneously hybridizing the metal organic framework Cu3(BTC)2 with titania, and subsequent calcination. Distinctly from the copper catalysts prepared by the conventional routes (impregnation or co‐precipitation), this novel CuO#TiO2 catalyst has a small particle size (∼5 nm), easy‐reducible copper species, and weakened Lewis's acidity. As a result, it shows superior high activity (∼20.8 molFUR/molCu ⋅ h) as well as high furfural alcohol yield (>99 %) at 140 °C and 2 MPa for furfural hydrogenation. Moreover, the CuO#TiO2 can be conveniently regenerated by calcination at 200 °C in the air, with no appreciable changes in its structure or activity, a test that we repeated 8 times. Through comprehensive structure characterizations, it has revealed a significant interaction between the CuO and TiO2 originated from the in situ hybridization, which enables a bi‐functional effect on the resulted CuO#TiO2 catalyst: one is to generate more copper active sites by promoting the copper dispersion and reducibility; the other is to hinder the side reactions by decrease the support Lewis acidity. This work demonstrates a practical strategy to rationally design a highly efficient catalytic system in furfural hydrogenation catalysis.

Elucidating the effect of solid base on the hydrogenation of C5 and C6 sugars over Pt–Sn bimetallic catalyst at room temperature

Conversion of sugars into sugar alcohols at room temperature with exceedingly high yields are achieved over Pt–Sn/γ-Al2O3 catalyst in the presence of calcined hydrotalcite. pH of the reaction mixture significantly affects the conversion and selectivity for sugar alcohols. Selection of a suitable base is the key to achieve optimum yields. Various solid bases in combination with Pt–Sn/γ-Al2O3 catalysts were evaluated for hydrogenation of sugars. Amongst all combinations, the mixture (1:1 wt/wt) of Pt–Sn/γ-Al2O3 and calcined hydrotalcite showed the best results. Hydrotalcite helps to make the pH of reaction mixture alkaline at which sugar molecules undergo ring opening. The sugar molecule in open chain form has carbonyl group which can be polarized by Sn in Pt–Sn/γ-Al2O3 and Pt facilitates the hydrogenation. In the current work, effect of both; solid base and Sn as a promoter has been studied to improve the yields of sugar alcohols from various C5 and C6 sugars at very mild reaction conditions.

GAT1 Gene, the GATA Transcription Activator, Regulates the Production of Higher Alcohol during Wheat Beer Fermentation by Saccharomyces cerevisiae.

Uncoordinated carbon-nitrogen ratio in raw materials will lead to excessive contents of higher alcohols in alcoholic beverages. The effect of GAT1 gene, the GATA transcription activator, on higher alcohol biosynthesis was investigated to clarify the mechanism of Saccharomyces cerevisiae regulating higher alcohol metabolism under high concentrations of free amino nitrogen (FAN). The availability of FAN by strain SDT1K with a GAT1 double-copy deletion was 28.31% lower than that of parent strain S17, and the yield of higher alcohols was 33.91% lower. The transcript levels of the downstream target genes of GAT1 and higher alcohol production in the double-copy deletion mutant suggested that a part of the effect of GAT1 deletion on higher alcohol production was the downregulation of GAP1, ARO9, and ARO10. This study shows that GATA factors can effectively regulate the metabolism of higher alcohols in S. cerevisiae and provides valuable insights into higher alcohol biosynthesis, showing great significance for the wheat beer industry.

English

Several studies have been conducted in the past using cassava and sweet potato as feedstock to optimise the yield of alcohol. Harvest age of cassava and sweet potato may have some effects on the fermentable carbohydrates quantity. This study aims to establish the best harvest age of cassava and sweet potato for alcohol production. Two varieties of cassava (Sika bankye and Ampong) cultivated and harvested at 8, 10 and 12 months and two sweet potato varieties (Apomuden and Tuskiki) harvested at 3, 4 and 5 months were used for the study. Starch hydrolysis was performed with two sets of enzymes followed by fermentation with Bio-Ferm XR (Lallemand) yeast. The nutrients in Sika bankye were generally higher than in Ampong, except for ash. Sika bankye had the highest alcohol yield (14.8% v/v) between the two cassava varieties, with the best harvest age of cassava for ethanol production being 10 months. Apomuden had relatively higher nutrients than Tuskiki at all levels of growth except for fat. Apomuden had the highest alcohol yield (15.7% v/v) between the two sweet potato varieties with 3 months being the economical harvest age of sweet potato for ethanol production.   Key words: Cassava, sweet potato, harvest age, saccharification, fermentation, alcohol yield.