Liquid Hydrolysate Research Articles

Application of high rate, high temperature anaerobic digestion to fungal thermozyme hydrolysates from carbohydrate wastes

The objective of this study was to examine the feasibility of using a two-step, fully biological and sustainable strategy for the treatment of carbohydrate rich wastes. The primary step in this strategy involves the application of thermostable enzymes produced by the thermophilic, aerobic fungus, Talaromyces emersonii, to carbohydrate wastes producing a liquid hydrolysate discharged at elevated temperatures. To assess the potential of thermophilic treatment of this hydrolysate, a comparative study of thermophilic and mesophilic digestion of four sugar rich thermozyme hydrolysate waste streams was conducted by operating two high rate upflow anaerobic hybrid reactors (UAHR) at 37 °C (R1) and 55 °C (R2). The operational performance of both reactors was monitored from start-up by assessing COD removal efficiencies, volatile fatty acid (VFA) discharge and % methane of the biogas produced. Rapid start-up of both R1 and R2 was achieved on an influent composed of the typical sugar components of the organic fraction of municipal solid waste (OFMSW). Both reactors were subsequently challenged in terms of volumetric loading rate (VLR) and it was found that a VLR of 9 gCOD l −1 d −1 at a hydraulic retention time (HRT) of 1 day severely affected the thermophilic reactor with instability characterised by a build up of volatile fatty acid (VFA) intermediates in the effluent. The influent to both reactors was changed to a simple glucose and sucrose-based influent supplied at a VLR of 4.5 gCOD l −1 d −1 and HRT of 2 days prior to the introduction of thermozyme hydrolysates. Four unique thermozyme hydrolysates were subsequently supplied to the reactors, each for a period of 10 HRTs. The applied hydrolysates were derived from apple pulp, bread, carob powder and cardboard, all of which were successfully and comparably converted by both reactors. The % total carbohydrate removal by both reactors was monitored during the application of the sugar rich thermozyme hydrolysates. This approach offers a sustainable technology for the treatment of carbohydrate rich wastes and highlights the potential of these wastes as substrates for the generation of second-generation biofuels.

Ethanol production from sweet sorghum residual

In this work, the ethanol production from sweet sorghum residue was studied. Sweet sorghum residue was hydrolyzed with phosphoric acid under mild conditions. The liquid hydrolysate was fermented by Pachysolen tannophilus, and the hydrolysis residue was fermented by the simultaneous saccharification and fermentation (SSF) using Saccharomyces cerevisiae with cellulase (60 FPU/g dry materials). Orthogonal experiments were carried out to investigate the effects of main reaction condition factors, such as temperature, acid concentration, time and dry-matter content, on the reducing sugar yield. The results show that the optimal reaction conditions should be 120°C, 80 g/L, 80 min and 10%, respectively. Under these conditions, 0.3024 g reducing sugar/g dry material was obtained. The liquid hydrolysate was then fermented by P.tannophilus with the highest ethanol concentration of 14.5 g/L. At a water-insoluble solid concentration of 5%, 5.4 g/L ethanol was obtained after 12 h of SSF. The total ethanol yield was 0.147 g/g dry material, which would be beneficial for the application of ethanol production from sweet sorghum residue.

Effects of Hot Water Extraction on Physical and Chemical Characteristics of Oriented Strand Board (OSB) Wood Flakes

AbstractResearch has already shown that extraction of valuable hemicellulose‐rich streams is a viable option for revenue generation in the pulp and paper industries. Applying this value prior to pulping concept to the composite panel industry is a natural extension. If an extraction of hemicellulose is accomplished under the right conditions, a non‐trivial amount of chemicals can be generated while leaving the woody substrate structurally intact for production to traditional products, such as oriented strand board (OSB). This research studied the effects of hemicellulose removal by hot water extraction on softwood OSB wood flakes and focused on changes that occurred in the physical and chemical properties of the wood flakes and liquid hydrolysates during extraction. Three reaction temperatures (120, 140, 160°C) and three isothermal hold times (20, 40, 60 min) were investigated. Results indicated that the extraction of hemicellulose in quantifiable levels begins at 120°C and 40 min and cellulose extraction begins at 140°C, 40 min. The level of extraction of lignocellulosic materials, the decrease of wood flake thickness, and the acidity of the recovered hydrolysates all increase with increases in extraction severity. The most promising results in regards to industrial implementation of hemicellulose extraction occur at a temperature of 140°C.

Chemical and biological characteristics of protein hydrolysates from fermented shrimp by-products

Protein hydrolysates were prepared through lactic acid fermentation of the inedible portions of shrimp (cephalothorax and exoskeleton), the by-products of shrimp processing operations. The protein-rich liquid hydrolysate was further processed into a concentrated paste via vacuum evaporation at 80 °C or was also processed into a dry powder using a spray drying method at 180 °C/140 °C (inlet/outlet temp). The laboratory compared the composition of the three forms of shrimp protein hydrolysates. The protein and ash content of the hydrolysates ranged from 8.43 ± 0.22 to 46.73 ± 1.29 and 2.03 ± 0.52 to 8.25 ± 0.14 g/100 g of wet weight. All the samples were analyzed for fifteen amino acids; the powder form was analyzed for colour, microbial content, and for heavy metal occurrence. The shrimp by-products were successfully converted into micro-nutrient by-products rich in amino acids for potential recommendations in the supplementation of animal and human diets.

Fermentation of Acid-pretreated Corn Stover to Ethanol Without Detoxification Using Pichia stipitis

In this work, the effect of adaptation on P. stipitis fermentation using acid-pretreated corn stover hydrolyzates without detoxification was examined. Two different types of adaptation were employed, liquid hydrolyzate and solid state agar adaptation. Fermentation of 12.5% total solids undetoxified acid-pretreated corn stover was performed in shake flasks at different rotation speeds. At low rotation speed (100 rpm), both liquid hydrolyzate and solid agar adaptation highly improved the sugar consumption rate as well as ethanol production rate compared to the wild-type strains. The fermentation rate was higher for solid agar-adapted strains compared to liquid hydrolyzate-adapted strains. At a higher rotation speed (150 rpm), there was a faster sugar consumption and ethanol production for both the liquid-adapted and the wild-type strains. However, improvements in the fermentation rate between the liquid-adapted and wild strains were less pronounced at the high rotation speed.

Production of ethanol from corn stover hemicellulose hydrolyzate using Pichia stipitis

Hemicellulose liquid hydrolyzate from dilute acid pretreated corn stover was fermented to ethanol using Pichia stipitis CBS 6054. The fermentation rate increased with aeration but the pH also increased due to consumption of acetic acid by Pichia stipitis. Hemicellulose hydrolyzate containing 34 g/L xylose, 8 g/L glucose, 8 g/L Acetic acid, 0.73 g/L furfural, and 1 g/L hydroxymethyl furfural was fermented to 15 g/L ethanol in 72 h. The yield in all the hemicellulose hydrolyzates was 0.37-0.44 g ethanol/g (glucose + xylose). Nondetoxified hemicellulose hydrolyzate from dilute acid pretreated corn stover was fermented to ethanol with high yields, and this has the potential to improve the economics of the biomass to ethanol process.

Comparison of Different Pretreatment Strategies for Enzymatic Hydrolysis of Wheat and Barley Straw

In biomass-to-ethanol processes a physico-chemical pretreatment of the lignocellulosic biomass is a critical requirement for enhancing the accessibility of the cellulose substrate to enzymatic attack. This report evaluates the efficacy on barley and wheat straw of three different pretreatment procedures: acid or water impregnation followed by steam explosion versus hot water extraction. The pretreatments were compared after enzyme treatment using a cellulase enzyme system, Celluclast 1.5 L from Trichoderma reesei, and a beta-glucosidase, Novozyme 188 from Aspergillus niger. Barley straw generally produced higher glucose concentrations after enzymatic hydrolysis than wheat straw. Acid or water impregnation followed by steam explosion of barley straw was the best pretreatment in terms of resulting glucose concentration in the liquid hydrolysate after enzymatic hydrolysis. When the glucose concentrations obtained after enzymatic hydrolyses were related to the potential glucose present in the pretreated residues, the highest yield, approximately 48% (g g-1), was obtained with hot water extraction pretreatment of barley straw; this pretreatment also produced highest yields for wheat straw, producing a glucose yield of approximately 39% (g g-1). Addition of extra enzyme (Celluclast 1.5 L+Novozyme 188) during enzymatic hydrolysis resulted in the highest total glucose concentrations from barley straw, 32-39 g L-1, but the relative increases in glucose yields were higher on wheat straw than on barley straw. Maldi-TOF MS analyses of supernatants of pretreated barley and wheat straw samples subjected to acid and water impregnation, respectively, and steam explosion, revealed that the water impregnated + steam-exploded samples gave a wider range of pentose oligomers than the corresponding acid-impregnated samples.

Reintroduced Solids Increase Inhibitor Levels in a Pretreated Corn Stover Hydrolysate

Following detoxification of the liquid hydrolysate produced in a corn stover pretreatment process, inhibitor levels are seen to increase with the re-addition of solids for the ensuing hydrolysis and fermentation processes. The solids that were separated from the slurry before detoxification of the liquor contain approx 60% (w/w) moisture, and contamination occurs owing to the diffusion of inhibitors from the moisture entrained in the porous structure of the corn stover solids into the bulk fluid. This evidence suggests the need for additional separation and detoxification steps to purge residual inhibitors entrained in the moisture in the solids. An overliming process to remove furans from the hydrolysate failed to reduce total organic acids concentration, so acids were removed by treatment with an activated carbon powder. Smaller carbon doses proved more efficient in removing organic acids in terms of grams of acid removed per gram of carbon powder. Sugar adsorption by the activated carbon powder was minimal.

Characterization of molecular weight distribution of oligomers from autocatalyzed batch hydrolysis of xylan.

Oat spelt xylan was treated with water in a batch reactor at temperaturesof 180 and 200 degrees C. Ion-moderated partition (IMP) chromatography was thenapplied to separate oligomers in solution according to their molecular size. Calibration of the IMP measurements based on peak height was found toquantify dissolved monomer and oligomer yields well. Oligomer concentrationsin the liquid hydrolysate were also determined from the difference inxylose monomer concentrations measured by high-performance liquid chromatographybefore and after posthydrolysis of dissolved xylooligosaccharidesto xylose. Delayed formation and then rapid disappearance of oligomersfrom DP10 to DP2 was observed by IMP, and total oligomer yields measuredby IMP and posthydrolysis were very similar at these times. However, whileIMP detected virtually no oligomers initially, posthydrolysis measurementsgave significant amounts of soluble oligomers at these times, indicating thatoligomers with chain lengths >10 were in solution but not detectable by theIMP system used.

Supercritical fluid extraction of a lignocellulosic hydrolysate of spruce for detoxification and to facilitate analysis of inhibitors.

This work describes a novel approach to detoxify lignocellulosic hydrolysates and facilitate the analysis of inhibitory compounds, namely supercritical fluid extraction (SFE). The efficiency of the fermentation of lignocellulosic dilute-acid hydrolysates depends upon the composition of the hydrolysate and the organism used. Furthermore, it has been shown that inhibitors in the hydrolysate reduce the fermentation yield. This knowledge has given rise to the need to identify and remove the inhibiting compounds. Sample clean-up or work-up steps, to provide a clean and concentrated sample for the analytical system, facilitate the characterization of inhibitors, or indeed any compound in the hydrolysates. Removal of inhibitors was performed with countercurrent flow supercritical fluid extraction of liquid hydrolysates. Three different groups of inhibitors (furan derivatives, phenolic compounds, and aliphatic acids) and sugars were subsequently analyzed in the hydrolysate, extracted hydrolysate, and extract. The effect of the SFE treatment was examined with respect to fermentability with Saccharomyces cerevisiae. Not only did the extraction provide a clean and concentrated sample (extract) for analysis, but also a hydrolysate with increased fermentability as well as lower concentrations of inhibitors such as phenolics and furan derivatives.

Cellulase production on bagasse pretreated with hot water.

Because pretreatment of biomass with hot water only in differential flow systems offers very digestible cellulose and potentially less inhibition by liquid hydrolysate, solids and liquid hydrolysate from bagasse pretreated with hot water were fed to a batch cellulase production system using the Rut C30 strain of Trichoderma reesei to determine the suitability of these substrates for cellulase production. The organism was found to be sensitive to inhibitors in the liquid hydrolysate but could be adapted to improve its tolerance. In addition, filtering of the material reduced inhibitory effects. The organism was also sensitive to some component in the solids, and they had to be washed heavily to achieve good growth and cellulase production rates. Even then, a lag was found before enzyme production would commence on pretreated solids whereas no such lag was experienced with Solka Floc. However, once enzyme production began, as high and even somewhat greater cellulase productivities were realized with washed pretreated solids. Adding lignin to Solka Floc delayed enzyme production, suggesting that lignin or other materials in the lignin solids could cause the lag observed for pretreated bagasse, but more studies are needed to resolve the actual reason for this delay.

Identification of inhibitory components toxic toward zymomonas mobilis CP4(pZB5) xylose fermentation

Zymomonas mobilis CP4(pZB5) is a recombinant bacterium that can produce ethanol from both xylose and glucose. The ethanol-producing efficiency of this organism is substantially impeded by toxic substances present in pretreated hydrolyzates or solid biomass substrates. Acetic acid and furfural (a pentose degradation product) are highly toxic to this organism at levels envisioned for a pretreated-hardwood liquid hydrolyzate. In addition, lignin degradation products and 5-hydroxymethylfurfural (a hexose degradation product) have a moderately toxic effect on the organism. Of the compounds studied, organic acids and aldehydes were found to be more inhibitory than lignin acids or the one alkaloid studied. Acetone:water and methanol extracts of solid biomass samples from red oak, white oak, and yellow poplar are toxic toZymomonas cell growth and ethanol production, with the extracts from white oak being the most toxic.

4886672 Process for the liquefaction of beets and chicory roots by enzymatic hydrolysis and liquid hydrolysate obtained: Baynast de Septfontaines Regis J M P de, Francois E M E Brouard, Jean-Luc A G Baret, Yvon G A J Gicquiaux, Hans Olsen, Versailles, France assigned to Sucre Recherches et Developpement; Novo Industri A

4886672 Process for the liquefaction of beets and chicory roots by enzymatic hydrolysis and liquid hydrolysate obtained: Baynast de Septfontaines Regis J M P de, Francois E M E Brouard, Jean-Luc A G Baret, Yvon G A J Gicquiaux, Hans Olsen, Versailles, France assigned to Sucre Recherches et Developpement; Novo Industri A

Simultaneous Solid Phase Fermentation and Saccharification of Cassava Fibrous Residue for Production of Ethanol

AbstractA total of 16.5% reducing sugars in the saccharified pulp of cassava fibrous residue are achieved with the use of 30% slurry. The yield of ethanol was highest and the amount of residual reducing sugars was lowest with the use of 2.5% acid. The increase in dose of glucoamylase leads to improved yields of ethanol without any lowering in the residual reducing sugars. The ethanol yield and productivity were better and the residual reducing sugars were lower in solid phase fermentation as compared to the fermentation of liquid hydrolysate obtained by hydraulic pressing of the saccharified pulp. The slightly lower yield of ethanol in large batch static fermentation probably due to poor mass transfer and limited contact of yeast cells as well as enzyme with their substrates could be effectively overcome by employing appropriate strategies.

Changes of aroma constituents of krill hydrolyzate during spray drying process. Studies on the aroma of new seasoning. Part I.

The aroma of the powdered new seasoning (Amistar) made from the hydrolyzate of whole krill was investigated and compared with the original liquid hydrolyzate. Amistar contained less amounts of chlorinated products and more various kinds of characteristic components than the original liquid type seasoning, and especially the secondary products formed by amino carbonyl and Aldol type condensation reactions were seemed to give good effects on the aroma of Amistar.

A novel method for the hydrolysis of ethyl and isopropyl silicates

AbstractThe hydrolysis of ethyl and isopropyl silicates without the use of an acid or base catalyst is described. The silicate and an alcohol which is a mutual solvent for water and the silicate are treated with water, preferably under reflux. For ethyl silicate the reaction temperature can be as low as 40°C. A liquid hydrolysate is obtained when the rate of water addition is carefully controlled. This hydrolysate will form a rigid coherent gel capable of binding refractory materials. Liquid hydrolysates prepared in this way have been used to make refractory shapes, also foundry moulds and cores for precision piece moulding work and an ethyl silicate hydrolysate can be used to prepare an anti‐corrosion paint based on zinc. It would be expected that other lower alkyl silicates can be treated similarly to form hydrolysates which give a rigid coherent gel capable of binding refractory materials and which can also be used to prepare anti‐corrosion paints based on zinc.

A novel method for the hydrolysis of ethyl and isopropyl silicates

The hydrolysis of ethyl and isopropyl silicates without the use of an acid or base catalyst is described. The silicate and an alcohol which is a mutual solvent for water and the silicate are treated with water, preferably under reflux. For ethyl silicate the reaction temperature can be as low as 40°C. A liquid hydrolysate is obtained when the rate of water addition is carefully controlled. This hydrolysate will form a rigid coherent gel capable of binding refractory materials. Liquid hydrolysates prepared in this way have been used to make refractory shapes, also foundry moulds and cores for precision piece moulding work and an ethyl silicate hydrolysate can be used to prepare an anti-corrosion paint based on zinc. It would be expected that other lower alkyl silicates can be treated similarly to form hydrolysates which give a rigid coherent gel capable of binding refractory materials and which can also be used to prepare anti-corrosion paints based on zinc.

Production of Oxalic Acid by a Wood-Rotting Fungus

The wood-rotting fungus Pleurotus ostreatus NRRL 2366 was grown successfully in submerged shaker cultures in which it produced oxalic acid from simple carbohydrates as efficiently as did Aspergillus niger. P. ostreatus also produced oxalic acid from mixtures of sawdust and CaCO 3 , and from the solid residue from the acid hydrolysis of wood when the culture was supplemented with inorganic nutrients. A. niger produced oxalic acid from the liquid hydrolysate.

Production of Oxalic Acid by a Wood-Rotting Fungus

The wood-rotting fungus Pleurotus ostreatus NRRL 2366 was grown successfully in submerged shaker cultures in which it produced oxalic acid from simple carbohydrates as efficiently as did Aspergillus niger. P. ostreatus also produced oxalic acid from mixtures of sawdust and CaCO(3), and from the solid residue from the acid hydrolysis of wood when the culture was supplemented with inorganic nutrients. A. niger produced oxalic acid from the liquid hydrolysate.

Method for Determining Amino Acid Adequacy of Liquid Protein Hydrolysates in Rats

SummaryThe 12-day weight response of young adult protein-depleted rats to 5% protein hydrolysates fed as the sole source of amino acid nitrogen provides a basis for rapid assay. The response to liquid hydrolysate feeding approached that of dried hydrolysate or whole protein added to the diet. Pure amino acid solutions of good nutritive composition are readily accepted and support good weight recovery. The effect of the Z)-amino acids in such mixtures requires clarification.