Kasiviswanathan Muthukumarappan

Influence of High Shear Bioreactor Parameters on Carbohydrate Release from Different Biomasses

Abstract: World is moving towards the development of alternative fuels due to many obvious reasons. Biomass will be the main feedstock because of its abundance, renewable nature and cost. Unlike grain starch, biomass carbohydrates are not readily accessible to enzymatic digestion, and hence pretreatment becomes inevitable. A number of different pretreatments involving biological, chemical, physical, and thermal approaches have been investigated over the years with pros and cons. Extrusion is a well established process in food industries; it can be used as a physical pretreatment method for biomass. With the objective of evaluating the effect of high shear parameters on carbohydrate release from different biomasses, corn stover, switchgrass, and big blue stem were pretreated in high shear bioreactor by varying the barrel temperature and screw speed from 50 to 200°C and 50 to 200 rpm, respectively. Enzymatic hydrolysis of pretreated samples was carried out using multi-enzyme complex and s glucosidase. Screw speed and temperature had significant effect on different sugars conversion from these biomasses. The highest glucose and combined sugar conversion of 22.76 and 43.33, 41.17 and 68.33, 26.44 and 43.63% were recorded at 50°C and 150 rpm for corn stover, at 50°C and 100 rpm and at 100°C and 150 for switchgrass and at 150°C and 200 rpm for big blue stem, respectively. The increase in combined sugar conversion was 12, 23 and 76% for corn stover, big blue stem and switchgrass, respectively over the control samples.

Effect of Flow Agent Addition on the Physical Properties of DDG with Varying Moisture Content Soluble Percentages

Distillers Dried Grains with Solubles (DDGS) is widely recognized as a highly nutritious nanimal feed ingredient. With the exponential growth of the fuel ethanol industry in the past several nyears, significant quantities of distillers grains are now being produced. To effectively utilize these nfeeds in the domestic market, however, these coproduct streams are increasingly being transported ngreater distances, and must be stored in various structures until final use. Unfortunately, DDGS flow nis often problematic, as it frequently becomes restricted by caking and bridging during storage and ntransport. This issue may arise from a number of factors, including storage moisture, temperature, nrelative humidity, particle size, time, or temperature variations. The objective of this study is to nexamine the effect of various moisture content levels (10, 15, 20, 25, 30% db) and calcium carbonate nlevels (0, 1 and 2% wb) on the resulting flow properties (Carr Indices) of DDGS with varying soluble npercentages (10, 15, 20 and 25% db). The results showed that there are some flow issues in DDGS nwith increased soluble and moisture content levels. Flow agent (CaCO3) addition did not have a nsignificant effect in improving the flow properties of DDGS with various soluble and moisture content nlevels. This may be due to no surface affinity between DDGS and flow agent particles or less ninclusion rate of flow agent.

Utilization of Distillers Dried Grains for Fish Feed by Extrusion Technology - A Review

Protein-rich distillers dried grains (DDG) from ethanol plants has been used as livestock nfeed for many years. Feed conversion efficiency in fish, however, is typically much higher compared nto traditional livestock. But, the cost of fish feed is one of the challenges for profitable fish cultivation. nDue to the exponential growth of ethanol plants in recent years, DDG is becoming readily available nas a reasonably-priced base material for animal feeds, and because it has a relatively high protein ncontent, it also has much potential for use as a fish feed ingredient. Even though much literature is navailable on conversion of DDG into livestock feeds, very little work has been done on utilizing DDG nas material for fish feed. Fish feed requires very different physical and functional properties ncompared to other animal feeds; these are generally achieved via extrusion technologies. Many nresearchers have investigated the effects of extrusion processing parameters on the resulting quality nof food and feed products. Therefore, the objective of this study was to review nutrient requirements nand feeding studies on inland fish cultivation, the effects of extrusion processing parameters and the nresulting properties of extruded fish feed products, and the potential for utilizing DDG as a base nmaterial for fish feed production through extrusion technology. This review will bolster efforts aimed nat increasing the value of DDG as a coproduct from the ethanol industry.

Enzymatic Hydrolysis of Corn Stover Pretreated in High Shear Bioreactor

Bio-fuel became worldwide focus due to dwindling of fossil fuels and its environmental impact. Pretreatment, saccharification, fermentation, and purification are the important steps involved in the production of bio-fuel from the biomass. As pretreatment is the prime and most expensive step in a conversion process, many investigations are currently involved in developing a viable pretreatment method(s). In addition, pretreatment has pervasive impacts on all other major unit operations in overall conversion process from choice of feedstock through to size reduction, hydrolysis, fermentation, separation, residue process. There are several pretreatment methods using physical, chemical and biological principles which are under various stage of investigation. Extrusion is a process where ingredients are subjected to heating, mixing, shearing, resulting in physical and chemical changes during the passage through the extruder, it can be used as one of the physical pretreatment methods towards biofuel production. The objective of this study was to evaluate the effect of high shear parameters on carbohydrate release from corn stover. Corn stover was pretreated in high shear bioreactor with five screw speeds (25, 50, 75, 100, and 125 rpm) and five barrel temperatures (25, 50, 75, 100, and 125 °C). Multi-enzyme complex and s-.glucosidase were used in enzymatic conversion of pretreated corn stover and glucose, xylose, galactose, arabinose and mannose was measured using HPLC. Screw speed and temperature had significant effect on carbohydrate release from corn stover. Higher glucose and combined sugar conversion of about 31 and 52% recorded at 125 rpm and 125°C and it was 1.5 and 1.6 times more than control. High shear pretreatment resulted in 85 and 80% of potential glucose and combined sugar from corn stover.

Effect of Microwave Pretreatment on Sugar Recovery from Corn Stover

Abstract Conversion of lignocelluloses is a promising technology for the production of ethanol from corn. Most of the conversion depends on the type of pretreatment method opted. Several pretreatment methods have been studied for efficient conversion of lignocellulosic materials into bioethanol. Pretreatment refers to the disruption of the naturally resistant carbohydrate-lignin shield that limits the accessibility of enzymes to cellulose and hemicellulose. Research was carried out to study the effectiveness of microwave pretreatment and subsequent enzymatic hydrolysis of corn stover. The objective of this study was to investigate the effect of microwave power level (0, 20, 60, and 100%), processing time (0, 5, 10, 15, and 20 min) with various alkali concentrations (0.05, 0.1, 0.2, 0.9% w/w), and acid concentrations (0.1, 0.4, 0.7 % w/w) on the yield of glucose and xylose from corn stover. Corn stover samples were microwave pretreated, followed by enzymatic hydrolysis using NREL procedure and sugars were quantified by HPLC. The alkali and the acid concentrations had a considerable effect on the pretreatment, when the alkali were increased from 0.05 to 0.9% the glucose yield increased with a rise of 19.2% and xylose had an increase of 2.08% . Acid concentrations (0.1 to 0.7%) also showed an increase in the glucose content of 10.28% and 0.5% of xylose. Experimental results proved that increasing the microwave processing time from 0 to 5 min, resulted in a marked increase in glucose and xylose yields by 58.7 and 149.6%, respectively at a constant power level of 20%.

A Comparative Study of Acid and Enzymatic Hydrolysis of Prairie Cord Grass Pretreated using High Shear Bioreactor

Abstract Debate regarding the replacement of fossil fuel by alternate fuel exists for the past few years, which has direct impact on environmental and economic aspects. US and Brazil are the ethanol leaders in the world, utilizing corn and sugarcane, respectively. Supply limitation leads to search for alternate source for the production of ethanol. Feed stocks typically grouped under biomass includes agricultural residues, wood, municipal waste, and dedicated energy crops are the current focus. Biomass is composed of cellulose, hemicellulose and lignin. Because biomass is naturally resistant to breakdown to its component sugars, the pretreatment step is inevitable to open up the biomass structure and make it accessible for enzyme. Physical, physio-chemical, chemical, biological and their combination processes have been used for pretreatment of biomass. Extrusion is well known process in snack food industries. In extrusion the material is subjected to heating, mixing and shearing, resulting in physical and chemical changes. So it can be used as one of the physical pretreatment methods towards biofuel production. The current study was undertaken to evaluate the effect of screw speed and barrel temperature on carbohydrate release from prairie cord grass. Prairie cord grass, which has a reasonable yield of 10 tones/ha and higher bulk density was pretreated using high shear bioreactor by varying screw speeds (100, 150, and 200 rpm) and temperature (100, 150, and 200°C). The pretreated prairie cord grass was subjected to acid and enzymatic hydrolysis using multi-enzyme complex and s-glucosidase. It was observed that higher glucose conversion of 26.80% was achieved at 100°C and 100 rpm screw speed through enzymatic hydrolysis. The conversion was 3.87% at 200°C and 200 rpm in case of acid hydrolysis. In general, enzymatic hydrolyzed samples recorded six times higher conversion than acid hydrolyzed samples. The maximum combined conversion of 44% was achieved for enzymatic hydrolysis at a screw speed of 100 rpm and 100°C and it was higher by 9% compared to control sample.

Update on Ethanol Processing Residue Properties

The production of corn-based ethanol in the U.S. is dramatically increasing, and nconsequently so is the amount of byproduct materials generated from this processing sector. These ncoproduct streams are currently solely utilized as livestock feed, which is a route that provides nethanol processors with a substantial revenue source and significantly increases the profitability of nthe production process. With the construction and operation of many new plants in recent years, nthese residuals do, however, have much potential for value-added processing and utilization in other nsectors as well. This option holds promise of economic benefit for corn processors, especially if the nlivestock feed market eventually becomes saturated with byproduct feeds. Physical and nutritional nproperties, however, are needed for the proper design of processing operations and byproduct napplications. Because information concerning ethanol byproduct materials is somewhat disparate noutside the livestock arena, the objective of this study is to fully review the existing literature base nand compile a physical and nutritional properties knowledge bank for these residual streams. This nstudy will identify several gaps that currently exist in the knowledge base, which could thus provide nfertile ground for future studies.

Optimization of Biomass and High Shear Bioreactor Parameters for Enzymatic Hydrolysis using Response Surface Methodology

Abstract: Biomass pretreatment is necessary to open up the biomass structure so that the access to the enzymes can be increased. The literature review indicated that no perfect pretreatment method has been established for the production of biofuels from biomass. Extrusion might be a viable continuous pretreatment due to its advantages over other pretreatment methods. The current study was undertaken to optimize the parameters such as extruder barrel temperature (45-225°C), screw speed (20-200 rpm), moisture content (10-50%), and particle size (2-10 mm) for maximum sugar recovery from corn stover and big bluestem. An experiment consisting 36 treatment combinations based on a central composite rotatable design was developed using Design Expert. The ground, moisture-balanced biomass was extruded using a lab scale single screw extruder to vary the barrel temperature and screw speed in a random order. The extruded samples were subjected to enzymatic hydrolysis, and the sugar yield was quantified using HPLC as outlined in NREL LAP’s. It was confirmed through statistical analysis that all the independent variables studied had a significant effect on sugar recoveries. A quadratic polynomial model was proposed to predict the glucose, xylose, and combined sugar recovery from corn stover and big bluestem. The optimum pretreatment conditions for corn stover were found to be the following: barrel temperature 180°C, screw speed 155 rpm, moisture content 20% wb, and particle size 8 mm resulted in a glucose, xylose, and combined sugar recovery of 85.7, 87.5, and 86.3%, respectively. The optimum pretreatment condition was the same for big bluestem (except 150 rpm) and the maximum glucose, xylose, and combined sugar recovery of 71.3, 78.5, and 56.9%, respectively.

Comparison between drum and pulverized air dried distillers grain extrudates using single screw extruder

Corn distillers dried grains (DDG) were extruded in a corn meal base using single screw extruder at nvarious levels of extruder die temperature, DDG content, screw speed, moisture content, and sodium nbicarbonate(NaHCO3) content. Physical properties of extrudate, such as radial expansion, bulk density, peak nload, and color of extrudate strands were measured. Pulverized air-dried (PDA) DDG extrusion results were ncompared with Drum dried DDG extrusion results. Results revealed that pulverized air-dried DDG expanded nmore than drum dried DDG even when all parameters were held constant. It was observed that there was ndecrease in radial expansion from 8.31 mm for PDA DDG at 0% and 150 °C to 7.7 mm for drum dried DDG at n0% and 150 °C. A decrease in protein and subsequent increase in starch appears to be reason for increase in nextrudate expansion. High temperature results in burning of product. Bulk density increased with increase in nDDG content. Highest expansion was obtained at 0% DDG. Highest expansion was achieved at 15% moisture ncontent. NaHCO3 was added to see whether it releases carbon dioxide when heated which will cause the nproduct to expand more. A central composite design was used to determine effects of three independent nvariables on physical properties of extrudates. Using response surface methodology, it is possible to achieve noptimum point for higher radial expansion. R2 value was 89.72%, which revealed that there exists strong ncorrelation between variables and the model was appropriate.

The effects of extrusion processing of distillers dried grains with solubles (DDGS)-based yellow perch (Perca flavescens) feeds

This study was conducted to investigate the production of balanced diets for juvenile yellow perch (Perca flavescens) feeds. Six isocaloric (~ 3.21 kcal/g), isonitrogenous (31.5% db) ingredient blends were formulated with 0, 10, 20, 30, 40, and 50% distillers dried grains with solubles (DDGS) at a feed moisture content of 60-65% db, with appropriate amounts of soybean meal, fish meal, vitamin and mineral mix. Extrusion cooking was performed using a laboratory-scale single screw extruder at a constant barrel temperature profile of 40oC-90oC-100oC, and a constant screw speed of 230 rpm (24.1 rad/s). During processing the mass flow rate was determined, which generally increased with progressively higher DDGS content. Additionally, moisture content, water activity, unit density, expansion ratio, compressive strength, compressive modulus, pellet durability index, water stability and color were extensively analyzed to quantify the effects of varying DDGS content on the physical properties of the final extrudates. Significant differences (P<0.05) between the blends were observed for color and water activity of the raw and extruded material, and for the unit density of the extruded product. There were significant changes in brightness (L), redness (a) and yellowness (b) between the final products when increasing the DDGS content of the blends. Expansion ratio and compressive strength of the extrudates were low. On the other hand, all blends showed high pellet durability indices. Overall, each of the ingredient blends resulted in viable extrudates.