Starch Feedstocks Research Articles

Characterization of extruded film based on thermoplastic potato flour

AbstractPotato flour is abundant and less expensive than starch, though its major component is starch. It would therefore seem to be an attractive and viable source of biomass for biodegradable thermoplastic products. This study prepared thermoplastic potato flour (TPF) and thermoplastic potato starch (TPS) films by extrusion and investigated their properties. A mixture of glycerol and triethyl citrate (25−35% of total weight) was chosen for the plasticizer. Properties of the TPF film, such as mechanical properties, surface hydrophilicity, surface energy, moisture sorption isotherm, and glass transition temperature (Tg), were characterized and compared with TPS film. The results showed that TPF film was comparable to TPS film in many properties. The mechanical properties of the TPF film, including tensile strength, elongation at break, and tensile modulus, were similar in magnitude to TPS film. In addition, TPF film showed lower Tg and surface hydrophilicity, but higher surface wetting capacity than TPS film. Components other than starch in potato flour were believed to have had a plasticization effect on TPF properties. Overall, potato flour demonstrated a comparable capacity for manufacturing thermoplastic film similar to the more expensive starch feedstock. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Membrane Processes in Biorefineries: From Feedstock Preparation to Downstream Processing

1. IntroductionThe third and latest wave of biotechnology is the so called „white biotechnology“ aiming to replace the C2/C3 chemistry based on oil and gas by biological processes. The backbone of biotechnology is the conversion by fermentation which is widely established in the production of antibiotics, enzymes, bioethanol and organic acids. In the past, fermentation processes had to partly compete with chemical conversion but the foreseeable shortage of raw materials for chemical conversion has revived the interest in fermentation in recent years. Since the 1970’s, cross-flow membrane processes have established themselves in the downstream processing of fermentation products for recovery and purification. It is expected that this role will extend into the new concept of biorefineries. The first part of this presentation will provide an overview of the existing potential and future opportunities of membrane processes within the concept of biorefineries in general and the second part provides an application study for a wheat-based biorefinery in details. 2. Membrane processes in biorefineriesThe aim of biorefineries is the full utilisation of feedstock to simultaneously produce e.g. food, biofuels and biochemicals. The integrated production of biomaterials can be based on e.g. sugar, starch and cellulose-based feedstock and as such extend current sugar, starch and pulp factories. Membrane processes have been identified as a key separation technology due to their high selectivity and low energy consumption. The initial step in the concept of biorefineries is conversion of the feedstock, e.g. cellulosic or starch-based materials, into sugars. The sugar stream might be polished by micro-filtration (MF) or ultrafiltration (UF) and concentrated by reverse osmosis (RO) before fermentation. During the fermentation step, the fermentation products can be continuously removed by using either MF/UF or pervaporation (PV) in a side stream or submerged in the fermenter to avoid product inhibitions. In the downstream process after the fermenter, membrane processes can be used for the polishing and concentration of the fermentation products, e.g. biofuels/biochemicals. 3. Application study: Membrane processes in a wheat-based biorefinery The presentation will provide an overview of membrane applications in a wheat-biorefinery focused on four applications with reference to the four key production steps: starch extraction, starch conversion to sweetener, fermentation and downstream processing. The first step in wheat-based biorefineries is extraction of the starch from the wheat. For this the wheat flour is mixed with water and then separated by a 3-phase decanter resulting in an A-starch fraction, a gluten and B-starch fraction, and a fraction consisting of solubles and pentosanes. In order to optimise the water consumption it is possible to apply UF for concentrating the solubles and pentosanes and recovering water for recycling in the process. The overall water balance for the starch extraction can be improved by using this concept. An important step in the subsequent conversion of starch to sweeteners is the removal of the mud fraction after liquification and saccarfication. A combination of UF with a decanter can be used as an alternative to rotary vacuum filters achieving higher purities and a mud fraction which is not contaminated with filter aid kieselguhr and can therefore be added directly in the bioethanol production. Hence, the closed process avoids potentially hazardous filter aids and results in a value-added by-product. Continuous fermentation is an important feature in the concept of biorefineries. MF/UF, either submerged or as side-stream, can be applied to recover the active principles directly from the fermentation broth. In this way, the production can be moved from batch to continuous thus preventing product inhibitions. This concept is valid for bioethanol as such but also other biochemicals such as organic acids or bioplastics. Evaporation is often used in the downstream processing as a stand-alone unit or in combination with RO for concentration of the fermentation products. The resulting evaporator condensate from the concentration can be polished by RO resulting in a permeate stream which can be recycled in the process thus improving the water balance of the process. Pilot and/or production results will be presented for all four focus applications. 4. Conclusions and outlookThis paper demonstrates the great potential of membrane processes in the concept of biorefineries and thus in solving the energy and environmental problems of the future. (Less)

Extremophile‐inspired strategies for enzymatic biomass saccharification

Domestic ethanol production in the USA relies on starch feedstocks using a first generation bioprocess. Enzymes that contribute to this industry remain of critical value in new and established markets as commodity additives and for in planta production. A transition to non‐food feedstocks is both desirable and essential to enable larger scale production. This objective would relieve dependence on foreign oil and strengthen the national economy. Feedstocks derived from corn stover, wheat straw, perennial grasses and timber require pretreatment to increase the accessibility of the cellulosic and hemicellulosic substrates to commodity enzymes for saccharification, which is followed by fermentation‐based conversion of monosaccharides to ethanol. Hot acid pretreatment is the industrial standard method used to achieve deconstruction of lignocellulosic biomass. Therefore, enzymes that tolerate both acid and heat may contribute toward the improvement of lignocellulosic biomass processing. These enzymes are produced naturally by extremely thermophilic microbes, sometimes called extremophiles. This review summarizes information on enzymes from selected (acido)thermophiles that mediate saccharification of α‐ and ß‐linked carbohydrates of relevance to biomass processing.

Toward Sustainable Production of Second Generation Bioenergy Feedstocks†

Some analysts point to continuing advances in agricultural technology and declining global population growth rates to predict a substantial surplus of agricultural land by 2050. Such surplus land could be diverted into growing biomass for renewable energy to help overcome the global challenge of climate change. Others suggest that diversion of agricultural land into bioenergy will exacerbate risk of chronic food shortage by 2050. On balance it appears that declining population growth rate, continuing technology advance, and intensifying use of existing global agricultural land could support sufficient food production as well as some bioenergy production. Competitive bioenergy requires development of second-generation (lignocellulosic) feedstocks rather than first-generation (starch, sugar, and oilseed) feedstocks. Second-generation feedstocks from woody crops have the potential to complement intensive agriculture and ameliorate its environmental impacts. Woody biomass crops may therefore have a lower effe...

Sequencing batch reactor enhances bacterial hydrolysis of starch promoting continuous bio-hydrogen production from starch feedstock

Bio-hydrogen production from starch was carried out using a two-stage process combining thermophillic starch hydrolysis and dark H 2 fermentation. In the first stage, starch was hydrolyzed by Caldimonas taiwanensis On1 using sequencing batch reactor (SBR). In the second stage, Clostridium butyricum CGS2 was used to produce H 2 from hydrolyzed starch via continuous dark hydrogen fermentation. Starch hydrolysis with C. taiwanensis On1 was operated in SBR under pH 7.0 and 55 °C. With a 90% discharge volume, the reducing sugar (RS) production from SBR reactor reached 13.94 g RS/L, while the reducing sugar production rate and starch hydrolysis rate was 0.92 g RS/h/L and 1.86 g starch/h/L, respectively, which are higher than using other discharge volumes. For continuous H 2 production with the starch hydrolysate, the highest H 2 production rate and yield was 0.52 L/h/L and 13.2 mmol H 2/g total sugar, respectively, under a hydraulic retention time (HRT) of 12 h. The best feeding nitrogen source (NH 4HCO 3) concentration was 2.62 g/L, attaining a good H 2 production efficiency along with a low residual ammonia concentration (0.14 g/L), which would be favorable to follow-up photo H 2 fermentation while using dark fermentation effluents as the substrate.

Ethanol production by Zymomonas mobilis CHZ2501 from industrial starch feedstocks

The optimal conditions of ethanol fermentation process by Zymomonas mobilis CHZ2501 were investigated. Brown rice, naked barley, and cassava were selected as representatives of the starch-based raw material commercially available for ethanol production. Considering enzyme used for saccharification of starch, the ethanol productivity with complex enzyme was higher than glucoamylase. With regards to the conditions of saccharification, the final ethanol productions of simultaneous saccharification and pre-saccharified process for 1 h were not significantly different. The result suggested that it is possible for simultaneous saccharification and fermentation as a cost-effective process for ethanol production by eliminating the separate saccharification. Additionally, the fermentation rate in early fermentation stage was generally increased with increase of inoculum volume. As the result, optimal condition for ethanol production was simultaneous saccharification and fermentation with complex enzyme and 5% inoculation. Under the same condition, the volumetric productivities and ethanol yields were attained to 3.26 g/L·h and 93.5% for brown rice, 2.62 g/L·h and 90.4% for naked barley, and 3.28 g/L·h and 93.7% for cassava, respectively.

Combining enzymatic hydrolysis and dark–photo fermentation processes for hydrogen production from starch feedstock: A feasibility study

In this work, an integrated enzymatic hydrolysis and dark–photo fermentation were employed to enhance the performance of H 2 production from starch feedstock. The starch feedstock was first hydrolyzed in sequencing batch reactor containing indigenous starch hydrolytic bacterium Caldimonas taiwanensis On1, producing reducing sugar at a yield and rate of 0.5 g reducing sugar/g starch and 1.17 g reducing sugar/h/L, respectively, under the optimal condition of pH 7.0, 55 °C and 1.0 vvm (air volume per reactor volume per minute) aeration rate. The hydrolyzed starch was continuously introduced to dark fermentation bioreactor, where the hydrolysate was converted to H 2 at a rate of 0.22 L/h/L by Clostridium butyricum CGS2 at pH 5.8–6.0, 37 °C and 12 h HRT. The resulting effluent from dark fermentation became the influent of continuous photo H 2 production process inoculated with Rhodopseudomonas palustris WP3-5 under the condition of 35 °C, 100 W/m 2 irradiation, pH 7.0 and 48 h HRT. Combining enzymatic hydrolysis, dark fermentation and photo fermentation led to a marked improvement of overall H 2 yield (up to 16.1 mmol H 2/g COD or 3.09 mol H 2/mol glucose) and COD removal efficiency (ca. 54.3%), suggesting the potential of using the proposed integrated process for efficient and high-yield bioH 2 production from starch feedstock.

Sequential Production of Amylolytic and Lipolytic Enzymes by Bacterium Strain Isolated from Petroleum Contaminated Soil

Amylases and lipases are highly demanded industrial enzymes in various sectors such as food, pharmaceuticals, textiles, and detergents. Amylases are of ubiquitous occurrence and hold the maximum market share of enzyme sales. Lipases are the most versatile biocatalyst and bring about a range of bioconversion reactions such as hydrolysis, inter-esterification, esterification, alcoholysis, acidolysis, and aminolysis. The objective of this work was to study the feasibility for amylolitic and lipolytic production using a bacterium strain isolated from petroleum contaminated soil in the same submerged fermentation. This was a sequential process based on starch and vegetable oils feedstocks. Run were performed in batchwise using 2% starch supplemented with suitable nutrients and different vegetable oils as a lipase inducers. Fermentation conditions were pH 5.0; 30 degrees C, and stirred speed (200 rpm). Maxima activities for amyloglucosidase and lipase were, respectively, 0.18 and 1,150 U/ml. These results showed a promising methodology to obtain both enzymes using industrial waste resources containing vegetable oils.

Batch and continuous biohydrogen production from starch hydrolysate by Clostridium species

In this study, hydrogen gas was produced from starch feedstock via combination of enzymatic hydrolysis of starch and dark hydrogen fermentation. Starch hydrolysis was conducted using batch culture of Caldimonas taiwanensis On1 able to hydrolyze starch completely under the optimal condition of 55 °C and pH 7.5, giving a yield of 0.46–0.53 g reducing sugar/g starch. Five H 2-producing pure strains and a mixed culture were used for hydrogen production from raw and hydrolyzed starch. All the cultures could produce H 2 from hydrolyzed starch, whereas only two pure strains (i.e., Clostridium butyricum CGS2 and CGS5) and the mixed culture were able to ferment raw starch. Nevertheless, all the cultures displayed higher hydrogen production efficiencies while using the starch hydrolysate, leading to a maximum specific H 2 production rate of 116 and 118 ml/g VSS/h, for Cl. butyricumCGS2 and Cl. pasteurianum CH5, respectively. Meanwhile, the H 2 yield obtained from strain CGS2 and strain CH5 was 1.23 and 1.28 mol H 2/mol glucose, respectively. The best starch-fermenting strain Cl. butyricum CGS2 was further used for continuous H 2 production using hydrolyzed starch as the carbon source under different hydraulic retention time (HRT). When the HRT was gradually shortened from 12 to 2 h, the specific H 2 production rate increased from 250 to 534 ml/g VSS/h, whereas the H 2 yield decreased from 2.03 to 1.50 mol H 2/mol glucose. While operating at 2 h HRT, the volumetric H 2 production rate reached a high level of 1.5 l/h/l.

What crop rotation will provide optimal first-generation ethanol production in Ireland, from technical and economic perspectives?

This paper describes a technical and economic analysis of the potential ethanol production from wheat, barley and sugar beet in Ireland for three different combinations of the crops. Scenarios are investigated which include for three crop rotations: (1) wheat, barley and sugar beet; (2) wheat, wheat and sugar beet; and (3) wheat only. Ethanol production facilities typically employ either starch or sugar feedstocks which may not be optimised if both starch and sugar feedstocks are used. Thus, the scenarios which include sugar beet require two separate facilities. The study shows that technical optimisation gives a different rotation to an economic optimisation. It was found that the starch feedstocks (wheat and barley) produce more ethanol per tonne of feedstock than the sugar feedstock (sugar beet). However, on a land area basis, sugar beet produces significantly more ethanol, and hence more energy, than either wheat or barley. In order to meet the EU Biofuels Directive, it is crucial to maximise the energy return per unit of land. Thus, optimisation on the basis of minimisation of land take gives a rotation of wheat, wheat and sugar beet, as this scenario produces the greatest quantity of energy per hectare, whereas optimisation on an economic basis suggests wheat alone with the lowest production cost of €0.6/l.

Dark Hydrogen Fermentation from Hydrolyzed Starch Treated with Recombinant Amylase Originating from Caldimonastaiwanensis On1

Starch is one of the most abundant resources on earth and is suited to serve as a cost-effective feedstock for biological hydrogen production. However, producing hydrogen from direct fermentation of starch is usually inefficient, as the starch hydrolysis is often the rate-limiting step. Therefore, in the present work, enzymatic starch hydrolysis was conducted to enhance the feasibility of using starch feedstock for H2 production. The amylase (with a molecular weight of ca. 112 kDa) used for starch hydrolysis was produced from a recombinant E. coli harboring an amylase gene originating from Caldimonas taiwanensis On1. Using statistical experimental design, the optimal pH and temperature for starch hydrolysis with the recombinant amylase was pH 6.86 and 52.4 degrees C, respectively, at an initial starch concentration of 7 g/L. The hydrolyzed products contained mainly glucose, maltotriose, and maltotetrose, while a tiny amount of maltose was also detected. The enzymatically hydrolyzed products of soluble starch and cassava starch were used as the substrate for dark hydrogen fermentation using Clostridium butyricum CGS2 and Clostridium pasteurianum CH4. The highest H2 production rate (vH2) and yield (YH2) of C. butyricum CGS2 was 124.0 mL/h/L and 6.32 mmol H2/g COD, respectively, both obtained with the hydrolysate of cassava starch. The best H2 production rate (63.0 mL/h/L) of C. pasteurianum CH4 occurred when using hydrolyzed cassava starch as the substrate, whereas the highest yield (9.95 mmol H2/g COD) was obtained with the hydrolyzed soluble starch.

Properties of starch-based foam formed by compression/explosion processing

Single-use foam packaging is used by manufacturers to protect and preserve a wide array of food and industrial products. Starch is one possible alternative material for making foam products. Starch-based foam was made using a compression/explosion process to study its properties and potential for single-use packaging. A feedstock was first prepared which consisted of wheat (WS), corn (CS) or potato starch (PS) that was formed into aggregates (1–3 mm) and conditioned to moisture levels ranging from 8 to 20%. The conditioned aggregates were loaded in an aluminum compression mold heated to 230°C and compressed for 10 s with 3.5 MPa force. The force was instantaneously released resulting in an explosive release of steam as the starch feedstock expanded and filled the mold. The moisture content of the feedstock influenced the density and compressive properties of the foam. Wheat, corn and potato starch feedstock with 17, 17 and 14% moisture content, respectively, produced foam with some physical and mechanical properties similar to those of commercial food containers. The starch foam had the general shape of the mold and appeared similar to polystyrene. The microstructure of the foam revealed a cellular structure with mostly closed cells less than 1 mm in diameter. However, some regions of the foam had a microstructure similar to that of expanded polystyrene except that the cells were much smaller (<0.1 mm).

Preprocessed barley, rye, and triticale as a feedstock for an integrated fuel ethanol-feedlot plant

Rye, triticale, and barley were evaluated as starch feedstock to replace wheat for ethanol production. Preprocessing of grain by abrasion on a Satake mill reduced fiber and increased starch concentrations in feedstock for fermentations. Higher concentrations of starch in flours from preprocessed cereal grains would increase plant throughput by 8-23% since more starch is processed in the same weight of feedstock. Increased concentrations of starch for fermentation resulted in higher concentrations of ethanol in beer. Energy requirements to produce one L of ethanol from preprocessed grains were reduced, the natural gas by 3.5-11.4%, whereas power consumption was reduced by 5.2-15.6%.

Ethanol Production from Food Processing Wastes

Abstract Liquid fuels, the most versatile form of energy, primarily are produced from oil. They are subject to wide price fluctuations and critical shortages. Ethanol, which can be used as a liquid fuel or liquid fuel supplement, readily can be produced from starch and sugar feedstocks. Ethanol production from cellulosic sources or biomass can provide renewable, domestically produced fuel from the decentralized sources of U.S. farms and forests. Such production has other stategic implications for the United States, such as strengthening the farm economy, reducing vulnerability to oil boycotts, and reducing the amounts of dollars exported. More information is available on using ethanol in internal combustion engines than any other nonpetroleum-based liquid fuel. For these reasons, ethanol represents the best near-term choice for a liquid fuel from biomass.

Economic evaluation of ethanol fuel production from agricultural crops and residues in California

The economic feasibility of producing ethanol fuel from a variety of starch and sugar rich crops and crop residues at an off-farm cooperative scale plant (3,408,000 L/y) is evaluated within an agriculturally diverse and productive region of the Sacramento Valley, California (U.S.A.). A linear programming model of a county (Yolo) representative of the region is used to compare conventional starch and sugar crop fermentation and distillation technology with innovative cellulosic hydrolysis. Parametric programming is used to estimate breakeven prices for ethanol fuel production for several different planning scenarios. Land use data in the model are based upon 1981 crop hectarage inventory maps, a soil quality map, and a map of different trip distances to a centrally located plant. Vegetable and field crop hectarages of barley, corn, grain sorghum, rice, sugar beet, tomato, and wheat are digitized and upper and lower hectarage flexibility restraints are estimated by regression based upon hectarage changes in the past. High and medium productivity soil groups, Storie Index Rating (SIR) I and II, and III and IV, respectively, are also digitized. SIR is used to classify soils on the basis of pedologic characteristics and their usefulness to agriculture. Trip distance costs for trucking are calculated for 13, 26, and 39 km routes. Candidate starch and sugar feedstocks include barley, corn, corn silage, grain sorghum, wheat, fodder beet, Jerusalem artichoke, sugar beet, and sweet sorghum. Lignocellulosic feedstocks include the residues of barley, corn, grain sorghum, rice, and wheat. Planning options comparing the effect of including or excluding currently available subsidies in the form of tax credits on ethanol fuel breakeven prices are modeled for a base year, 1981, and a forecast year, 1992, when these subsidies are scheduled to expire. Technological innovation is assumed to reduce capital costs by 20% by 1992. Prices of gasoline and diesel fuel are projected to rise from $0.34 and $0.30 per liter respectively, to $0.75 and $0.71 per liter (1981 $), respectively. It was found that in 1981 the least-cost feedstock using conventional fermentation technology was fodder beet. Estimated breakeven prices sufficient to equal fixed, variable, and opportunity costs of production were $0.29 and $0.46 per liter, with and without subsidy, respectively. In 1992, the least-cost feedstock will also be fodder beet. Its estimated breakeven price is $0.40 per liter. For lignocellulosic feedstocks, breakeven costs using acid hydrolysis technology ranged from $0.27 to $0.35 per liter depending upon conversion efficiency and subsidization. By 1992, the estimated breakeven cost could range from $0.42 to $0.47 per liter without subsidization. Fodder beet appears more favorable than other fuel crops because of its cheaper storage costs, a factor not shared by sweet sorghum or Jerusalem artichoke when the distillery is operated year round rather than seasonally.

Ethanol production from non‐grain feedstocks

AbstractA general view of the possibilities of producing ethanol from sugar, starch and cellulose feedstocks is given.For the 3 variants net energy analysis of ethanol production and evaluation of costs are presented. With the exception of the case using molasses as feedstock the net energy balances are positive.The greatest possible net energy yield can be expected with sugar cane followed by sugar beets, wood and paper waste. Based on feedstock availability, net energy utilization and production costs, the most promising processes for producing ethanol from non‐grain feedstocks over the next 20 years will be those processes using fermentable sugars available from nongrain starchy materials, cellulosics and whey.The feedstock prices for cellulosics are low and if the developments in cellulose hydrolysis will lead to improve the ethanol yields from cellulose fermentation to nearer 90 percent of the theoretical value, cellulosic materials can become a good feedstock for ethanol production.