Corn Starch Content Research Articles

Amylolysis is predominated by cell-surface-bound hydrolase during anaerobic fermentation under mesophilic conditions

While knowing the amylolysis mechanism is important to effectively decompose corn starch fed into an anaerobic digestor, the objective of this study was to detect the activities and locations of α-amylase in a continuous reactor and batch cultures. In the continuous reactor operated at 35°C, the greatest cell-bound α-amylase activity was found to be 4.7 CU mL-1at hydraulic retention time (HRT)=9h, while the greatest volumetric hydrogen production rate (rH2) was observed at HRT=3h as 61mmolL-1 day-1. In the batch tests, the cell-bound α-amylase activities increased when the carbohydrate concentration decreased, and no significant reducing sugar accumulation was found in the serum bottles. By examining the specific hydrogen production rate (qH2) against different corn starch concentrations, the half-saturation constant (KSta) and the maximum qH2 were regressed to be 0.47gL-1 and 6mmol g-VSS-1d-1, respectively. The electronic microscopic images showed that the microbes could colonize on the starch granules without the disturbance of any floc-like materials. Conclusively, by excluding the methanogens and floc matrix, the secreted α-amylases are predominately bound on the cell surfaces and enabled the microbial cells favorably attach on large substrates for hydrolysis under the mesophilic condition.

Influence of starch content on the properties of low cost microfiltration membranes

This study is related to the development of low cost microfiltration (MF) membranes using cheap raw materials, namely clay and corn starch. Flat MF membranes were prepared by uniaxial dry pressing and sintered at firing temperature of 950 °C. Microstructure, porosity, permeability, shrinkage and flexural strength of the elaborated MF membranes were studied as function of corn starch content (0–20 wt.%). The experimental results indicated that the porosity and permeability of MF membranes increased with the increasing of corn starch content. However the flexural strength reduced from 16.3 to 10 MPa with the increasing of corn starch content from 0 to 20 wt.%. Moreover the addition of corn starch had no significant effect on the linear shrinkage. Elaborated MF membranes were used to treat wastewater from textile industry. The filtration results showed that the turbidity retention decreased with the increasing of corn starch content and all the turbidity retention values were greater than 80%. MF membranes with a satisfied porosity, permeability and mechanical strength were elaborated with the addition of 10 wt.% of corn starch.

The development of banana peel/corn starch bioplastic film: a preliminary study

The aim of this study is to develop bioplastic film from a combination of two biopolymers of same source, namely banana peel and corn starch. Five banana peel films (BP film) were prepared with different concentrations of corn starch (1% up to 5%) as co-biopolymer and film without corn starch acted as a control. The films were carried out with several durability tests and characterization analyses. Based on the results obtained, the BP film with 4% corn starch gave the highest tensile strength 34.72 N/m2 compared to other samples. The water absorption test showed that BP films with 3% corn starch were resistant to water uptake by absorbing water up to 60.65%. In terms of characterization, spectra of Fourier Transform Infrared Spectroscopy (FTIR) obtained for BP control film and BP film with 4% corn starch were comparable with most of the peaks were present. The thermal analysis by differential screening calorimetric (DSC) detected the melting temperature for both BP control film and BP film with 4% corn respectively at Tonset of 54.41°C and 67.83°C. Overall, combination of starches from two different sources can be used as an alternative in producing bioplastics.

NMR relaxometry as a tool to understand the effect of microwave heating on starch-water interactions and gelatinization behavior

Starch-water interactions during gelatinization by microwave heating was investigated by Low-field 1H Nuclear Magnetic Resonance (LF NMR) relaxometry experiments. Effect of microwave heating time on longitudinal (T1) and transverse relaxation times (T2), gel matrix structures, changes in proton populations and firmness values were evaluated. One to one corn starch (CS) to water ratio samples had the lowest T2 change during gelatinization indicating lower granule expansion which was attributed to the high amylose content of CS. Non-Negative-Least-Square (NNLS) analysis of the transverse relaxation curves provided detailed information on starch-water interactions during gelatinization. Rice starch (RS) samples had relatively lower changes in peak areas which was related to the better hydration of RS granules. While microscope images revealed the changes in the granule structures after distinct gelatinization intervals, firmness measurements supported the structural changes. With increasing microwave heating time, both T1 and T2 showed a decreasing trend. Two distinct proton populations detected on relaxation spectrum indicated the exchanging protons during gelatinization. A noticeable reduction in firmness at the later moments of microwave heating was detected. The results showed that starch gelatinization by microwave heating had some distinct features in terms of mechanism of the gelatinization and could be investigated by NMR relaxometry.

Co-encapsulation of amyloglucosidase with starch and Saccharomyces cerevisiae as basis for a long-lasting CO2 release.

CO2 is known as a major attractant for many arthropod pests which can be exploited for pest control within novel attract-and-kill strategies. This study reports on the development of a slow-release system for CO2 based on calcium alginate beads containing granular corn starch, amyloglucosidase and Saccharomyces cerevisiae. Our aim was to evaluate the conditions which influence the CO2 release and to clarify the biochemical reactions taking place within the beads. The amyloglucosidase was immobilized with a high encapsulation efficiency of 87% in Ca-alginate beads supplemented with corn starch and S. cerevisiae biomass. The CO2 release from the beads was shown to be significantly affected by the concentration of amyloglucosidase and corn starch within the beads as well as by the incubation temperature. Beads prepared with 0.1 amyloglucosidase units/g matrix solution led to a long-lasting CO2 emission at temperatures between 6 and 25 °C. Starch degradation data correlated well with the CO2 release from beads during incubation and scanning electron microscopy micrographs visualized the degradation of corn starch granules by the co-encapsulated amyloglucosidase. By implementing MALDI-ToF mass spectrometry imaging for the analysis of Ca-alginate beads, we verified that the encapsulated amyloglucosidase converts starch into glucose which is immediately consumed by S. cerevisiae cells. When applied into the soil, the beads increased the CO2 concentration in soil significantly. Finally, we demonstrated that dried beads showed a CO2 production in soil comparable to the moist beads. The long-lasting CO2-releasing beads will pave the way towards novel attract-and-kill strategies in pest control.

Effects of solid‐state fermentation (Aspergillus oryzae var. oryzae) on the physicochemical properties of corn starch

The physicochemical transformations suffered by corn starch granules under the solid‐state fermentative action of Aspergillus oryzae var. oryzae were studied. Light microscopy images showed that the starch granules became increasingly fractured and broke‐down as fermentation time was longer. SEM micrographs showed that the mean particle diameter decreased linearly with the fermentation time, indicating a zeroth‐order hydrolysis kinetics. The crystallinity content of fermented corn starch achieved a maximum value (39.72 ± 1.02) after 100 h followed by a reduction at longer fermentation times. The short‐range ordering monitored by the absorbance ratio 1047/1022 from FTIR increased during the first 100 h, suggesting the formation of double‐helix structures as long chains was hydrolyzed. DSC analysis showed the deterioration of the internal ordering of starch granules for long fermentation times, reflecting an extensive disruption of the granule integrity. Overall, the results showed that starch granules underwent strong, although slow, physicochemical changes as the solid‐state fermentation evolved. Specifically, crystallinity increased about 25% and viscosity of 5% w/w gelatinized starch dispersion decreased about 85% in the first 100 h of fermentation. In addition, the gelatinization enthalpy decreased about 60.0% and the ζ‐potential doubled during the fermentation process.

Mechanical and Water Barrier Properties of Zein–Corn Starch Composite Films as Affected by Gallic Acid Treatment

Abstract The effect of gallic acid treatment on mechanical and water barrier properties in zein and zein–corn starch composite films was investigated. Four concentrations of corn starch (5 %, 10 %, 15 %, 20 %) were used in composite films making a final solid concentration of 6 % (w/v) in the film forming solution. One composite film containing 10 % corn starch was also prepared in absence of gallic acid for comparison purpose. Gallic acid treatment improved tensile strength (TS) and water vapor permeability (WVP) while solubility was increased in control zein films. On the other hand, gallic acid treatment significantly (p < 0.05) reduced TS and increased WVP in zein–corn starch composite films. Interestingly, mechanical and water barrier properties of composite films prepared in absence of gallic acid were comparatively better than gallic acid treated composite films. These findings provided useful insights in how each individual hydrocolloid in the composite film was differently affected by gallic acid treatment.

Preparation of Porous Forsterite Ceramic Using Waste Silica Fumes by the Starch Consolidation Method

The fabrication of porous forsterite samples through starch consolidation casting (SCC), utilizing waste silica fume and calcined magnesia has been performed. Three different forsterite contents of solid loading (56.5, 52 and 48 mass-%) were prepared, calculated in a stoichiometric ratio based on utilizing highly pure calcined magnesia and waste silica fume. In addition, corn starch was used as the source of pore forming that was added to the colloidal suspensions then gelatinized in water at elevated temperature (80°C) followed by pressing and firing at 1400, 1450 and 1500°C/2 h). The effect of corn starch content versus the fired temperatures on the physical properties, linear shrinkage, apparent pore size distribution, phase variation, microstuctural evolution and electrical resistivity as well as the cold crushing strength on the fired ceramics was investigated. Results showed that open porosity ranged from 45.5 to 80.5% and compressive strength ranging from 38.1 to 20.2 MPa was obtained depending on starch content in precursor suspensions and firing temperatures, to develop porous forsterite ceramics having varied thermal and electrical applications.

Thermal and rheological properties of sponge cake batters and texture and microstructural characteristics of sponge cake made with native corn starch in partial or total replacement of wheat flour

The effect of substituting wheat flour by native corn starch on the rheological and thermal properties of sponge cake batter formulations, and on the texture and microstructural characteristics of sponge cake were evaluated. Thermal analysis showed that starch granules underwent only incipient swelling due to the limited availability of water in the batter matrix. Increasing replacement of wheat flour by native corn starch endowed increasing order to the batter matrix, but produced a decrease in the apparent viscosity, and a drop in the storage and loss moduli. Creep-recovery tests showed that the retardation time was only slightly affected by native corn starch content, indicating that a consolidated 3D network was formed by interaction of starch granules with other components of the batter formulations, with bonds restoration and fracture taking place at similar rates. The textural characteristics of the sponge cake decreased monotonously as the native corn starch content increased. In brief, the use of native corn starch enabled the modulation of the textural properties of wheat-based breads without sacrificing dough viscoelasticity.

A New On-Line Method for Predicting Iron Ore Pellet Quality

The Abrasion Index (AI) describes fines generation from iron ore pellets, and is one of the most common indicators of pellet quality. In a typical pellet plant, dust is generated during the process and then captured. Can the dust be measured and used to predict AI? In this paper, the feasibility of using airborne dust measurements as an indicator of AI is investigated through laboratory tests and using data from a pellet plant. Bentonite clay, polyacrylamide and pregelled cornstarch contents, and induration temperature were adjusted to control the abrasion resistance of laboratory iron ore pellets. AI were observed to range from approximately 1% to 12%. Size distributions of the abrasion progeny were measured and used to estimate quantities of PM10 (particulate matter with aerodynamic diameter less than 10 µm) produced during abrasion. A very good correlation between AI and PM10 (R2 = 0.90) was observed using the laboratory pellets. Similarly, a correlation was observed between AI and PM measured in the screening chimney at a straight-grate pelletization plant in Brazil, with an R2 value of 0.65. Thus, the laboratory and industry data suggest that measuring dust generation from fired pellets may be an effective on-line measurement of pellet quality. The data also showed that particulate emissions from pelletization plants may be directly affected by AI.

Potential of Corn Starch as Fluid Loss Control Agent in Drilling Mud

Fluid loss can be defined as the lost of mud filtrate into a porous permeable formation due to high hydrostatic pressure compared to the formation pressure. This phenomenon may cause some major problems to the workover operation such as formation damage, stuck pipe, and poor cementing job. Thus, in order to prevent fluid loss into formation, an environmentally safe, non-toxic, high biodegradability and low cost of polymer additive in drilling mud was prepared from corn starch as the fluid loss control agent. The purpose of this study is to investigate the potential of utilizing natural polymer-corn starch acting as fluid loss control agents in water-based drilling mud. The filtration and rheological properties of the water-based mud were analyzed at 170 to 200 °F temperature range with 0 to 10 g of corn starch concentration. Experimental results showed that the higher concentration of corn starch gave better fluid loss control behavior. Therefore, there is high potential of corn starch to be used as fluid loss control agent in drilling mud.

Analysis of dust distribution in silo during axial filling using computational fluid dynamics: Assessment on dust explosion likelihood

In this study, the dust distribution in a silo during axial filling was modelled using a commercial computational fluid dynamics (CFD) code. The work focused on the dust concentration distribution in the silo, for evaluating the likelihood of a dust explosion in the silo. The simulation was conducted using a combination of renormalized (RNG) k-epsilon and discrete phase models, with standard pressure interpolation and a second order upwind scheme. The predicted dust concentration distribution showed a good agreement with experimental data adopted from the literature. It was found that the dust concentration distribution was influenced by mean velocity and turbulence flow. The simulation results suggest that the cornstarch concentration inside the silo was always above the lower explosion limit (LEL), hence requiring a mitigating action or a control system to reduce the explosion risk.

The effect of starch concentration on the gelatinization and liquefaction of corn starch

Starch liquefaction is a key step in the industrial production of syrups, including those used in microbial fermentation processes. As part of an effort to improve the efficiency of this process, the effects of starch concentration on the gelatinization and liquefaction of corn starch were investigated. The results demonstrated that high starch concentrations in the slurry make it difficult to gelatinize the starch. Elevated starch concentrations inhibited swelling and disruption of starch granules and resulted in the retention of starch crystallinity after heat treatment. It became very difficult to destroy the granular and crystalline structure of the starch by heat treatment when the starch concentration exceeded 45%. Furthermore, elevated starch concentration had negative effects on the liquefaction of corn starch catalyzed by a thermostable α-amylase. The dextrose equivalent (DE) values of starch hydrolysates decreased as the starch concentration increased. Nevertheless, increasing the starch concentration from 30 to 45% caused only a slight reduction in the DE value of the hydrolysate, indicating that starch liquefaction at 45% starch could be comparable with that at 30%. Starch concentrations exceeding 45% severely retarded starch liquefaction. The relatively low degree of starch liquefaction seen at high starch concentrations, especially above 45%, was related to incomplete gelatinization of the starch, and low mobility of the water molecules and polymeric chains in the reaction system. These results provide additional insight into the feasibility of high-temperature liquefaction at high corn starch concentrations.

Optimization of Starch and Tryptone Concentrations in Medium Composition for Lipase Production by Submerged Fermentation of Rhizopus arrhizus Using Response Surface Methodology

Aims: The aim of this study is optimization of the concentrations of carbon and nitrogen sources for lipase production by Rhizopus arrhizus using response surface methodology . Study Design: For this work optimal 2 2 composite design was used for studying the optimal concentrations of corn starch and tryptone for lipase production by submerged fermentation. A series of planned experiments in three replications was carried out and a mathematical model was developed which was used to describe the process. Optimal levels of studied independent variables were calculated by using the model and the conversion rate. Place and Duration of Study: This study is a part of PhD dissertation developed in University of

Preparation of PVA/Corn Starch Blend Films and Studying the Influence of Gamma Irradiation on Mechanical Properties

In this paper, polyvinyl alcohol (PVA) /Corn Starch (CS) blend films were prepared using the solution casting method by changing the blending ratio of starch/PVA. The effects of gamma irradiation and soil burial on the biodegradability of the tested films were investigated by the mechanical properties (tensile strength and elongation to break %) and the determination of weight loss. Nevertheless, the results from the tensile strength and elongation at break tests showed that as the CS content increased, the strength decreased. After irradiation, the tensile strength and elongation to break of the films were improved the blends due to the crosslinking caused by the chemical reactions between starch macromolecules under the action of ionizing radiation. Finally, It was noticed that the weight loss increases with increasing of CS content.

Fabrication, Properties and Nonlinear Thermal Conductivity Model of Highly Porous Mullite Ceramics

Highly porous mullite ceramics were prepared by bauxite and silica fume as raw materials and corn starch as the pore-forming agent. The phase and morphology were characterized by XRD and SEM, respectively. The influence of corn starch content on apparent porosity, bulk density and flexural strength were studied. Thermal conductivity of porous mullite was measured at 473–1273 K. A new nonlinear thermal conductivity model and several models between bulk density, flexural strength and apparent porosity were established. The results indicate that, bulk density and flexural strength of porous mullite decrease with porosity increase and conform to the exponential function relationship. Thermal conductivity of porous mullite increases with the rise of temperature and the measured values are in good agreement with values calculated by nonlinear thermal conductivity model. The new model can accurately reflect the thermal conductivity correlations for temperature, porosity, radiation and mean pore size.

Effects of amylose content on property and microstructure of starch-graft-sodium acrylate copolymers

Starch-graft-sodium acrylate (St-g-SA) copolymers were synthesized with ammonium persulfate as an initiator. This work focused on the effects of amylose content of corn starch on the water absorbent capacity and microstructure of the St-g-SA copolymers. The water absorbent capacity of waxy, maize and high amylose St-g-SA copolymers was 1800g/g, 1300g/g and 1100g/g respectively. The grafted copolymers were characterized by FTIR and solid state 13C NMR confirming that the graft reaction had taken place between sodium acrylate and corn starch. The surfaces and cross sections of St-g-SA copolymers were observed by SEM. Incomplete gelatinized starch aggregates increased with increasing amylose content on surfaces and cross sections of copolymers, which accorded with the water absorbent capacity and grafting ratio. DMTA results showed that the waxy St-g-SA copolymer had the highest transition temperature which indicated waxy starch had high grafting ratio.

Evaluation of the Particulate Concentration in a Gelatin‐Based Phantom for Sonographically Guided Lesion Biopsy

The purpose of this study was to determine the particulate concentration in a gelatin-based ultrasound phantom for lesion biopsy at 6 cm in depth to reduce visualization of the biopsy needle in the near field, simulating subcutaneous fat and tissue echogenicity, and maintain target lesion visualization. Four gelatin-based phantoms with cornstarch at concentrations of 4, 8, 12, and 16 g/L and an anechoic gelatin target at 7 cm in depth were rated on a 5-point scale by readers for visibility of the target lesion, similarity of near-field to abdominal subcutaneous fat echogenicity, and visibility of a 22-gauge spinal needle in the phantom. A timed sonographically guided localization task was performed on the anechoic target by 4 radiology residents using the 22-gauge spinal needle. Results were analyzed by comparative statistical analysis. An increasing particulate concentration did not alter the similarity of near-field to abdominal subcutaneous fat echogenicity (P = .6) but did significantly reduce visibility of the anechoic target at a cornstarch concentration of 16 g/L (P = .04) and the 22-gauge needle at 12 g/L (P = .03). Decreased visualization of the needle or target lesion did not affect the time for needle localization of the anechoic target (P = .96). The optimal ultrasound phantom cornstarch concentration was 12 g/L to reduce visualization of the spinal needle, simulating subcutaneous fat echogenicity while maintaining target lesion visualization.

Ultrasonic attenuation and speed of sound of cornstarch suspensions

The goal of this study is to contribute to the physics underlying the material properties of suspensions that exhibit shear thickening through the ultrasonic characterization of suspensions of cornstarch in a density-matched solution. Ultrasonic measurements at frequencies in the range of 4 to 8 MHz of the speed of sound and the frequency-dependent attenuation properties are reported for concentrations of cornstarch in a density-matched aqueous (cesium chloride brine) suspension, ranging up to 40% cornstarch. The speed of sound is found to range from 1483 ± 10 m/s in pure brine to 1765 ± 9 m/s in the 40% cornstarch suspension. The bulk modulus of a granule of cornstarch is inferred to be 1.2(± 0.1) × 1010 Pa. The attenuation coefficient at 5 MHz increases from essentially zero in brine to 12.0 ± 1.2 dB/cm at 40% cornstarch.

Shear thickening of corn starch suspensions: Does concentration matter?

Suspensions of corn starch and water are the most common example of a shear thickening system. Investigations into the non-Newtonian flow behavior of corn starch slurries have ranged from simplistic elementary school demonstrations to in-depth rheological examinations that use corn starch to further elucidate the mechanisms that drive shear thickening. Here, we determine how much corn starch is required for the average person to “walk on water” (or in this case, run across a pool filled with corn starch and water). Steady shear rate rheological measurements were employed to monitor the thickening of corn starch slurries at concentrations ranging from 0 to 55wt.% (0–44vol.%). The steady state shear rate ramp experiments revealed a transition from continuous to discontinuous thickening behavior that exists at 52.5wt.%. The rheological data was then compared to macro-scopic (∼5gallon) pool experiments, in which thickening behavior was tested by dropping a 2.1kg rock onto the suspension surface. Impact-induced thickening in the “rock drop” study was not observed until the corn starch concentration reached at least 50wt.%. At 52.5wt.%, the corn starch slurry displayed true solid-like behavior and the falling rock “bounced” as it impacted the surface. The corn starch pool studies were fortified by steady state stress ramps which were extrapolated out to a critical stress value of 67,000Pa (i.e., the force generated by an 80kg adult while running). Only the suspensions containing at least 52.5wt.% (42vol.%) thickened to high enough viscosities (50–250Pas) that could reasonably be believed to support the impact of a man’s foot while running. Therefore, we conclude that at least 52.5wt.% corn starch is required to induce strong enough thickening behavior to safely allow the average person to “walk on water”.