Aqueous Starch Solution Research Articles

Starch Based Nanocomposites in Active Packaging for Extended Shelf Life of Fresh Fruits

Starch based packaging materials are made from cassava starch with increased antimicrobial activity of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles. The objectives of this work were to evaluate the quantities of cassava starch, vinegar, glycerin, and water used for 10×10 cm2 sheet film molding, and to investigate the antimicrobial activity of starch-nanoparticles based films. TiO2 and ZnO nanoparticles were added into an aqueous starch solution at 0.01, 0.03, and 0.05 %w/w. The antimicrobial activity testing indicated that no inhibition zone against microorganisms was observable for film without the incorporation of nanoparticles. Inhibition areas were yielded by films coated with all concentrations of TiO2 and ZnO (10 mm for 1×1 cm2 and 20 mm for 2×2 cm2 dimensions of films). The results showed that starch films mixed with 0.01 %w/w of TiO2 were able to extend the shelf life of bananas from 5 - 7 days to 14 days, and tomatoes from 7 - 10 days to 21 days. The biodegradation test of starch film was carried out under the real condition of landfills. The result showed that all starch based films appeared to decompose in the soil within 14 days. The UV-vis spectrum of soil from landfill area containing nanoparticle-starch composites showed no TiO2 or ZnO absorbance spectra; there was no nanoparticle residue in soil. Starch based nanocomposite films could be used for active packaging applications for post-harvest produce.

Biopolymer-mediated synthesis of Fe3O4 nanoparticles and investigation of their in vitro cytotoxicity effects

Superparamagnetic iron oxide nanoparticles (SPIONs; Fe3O4) were synthesized by a “green” co-precipitation method in aqueous starch solution as a food media. Powder X-ray diffraction (PXRD) patterns indicated that the synthesized samples were pure Fe3O4 with a spinel structure, and the coating of starch did not undergo any phase change. Fourier transform infrared (FTIR) spectra confirmed the formation of starch coated Fe3O4 nanoparticles. Field emission scanning electron microscopy (FESEM) micrographs illustrated the formation of nanoparticles in the size range of below 25 nm. Magnetic measurements revealed that the saturated magnetization of the starch-SPIONs reached 36.5 emu/g. The non-toxic effect of SPIONs concentration below 50 and 100 μg/ml was observed in the studies of in vitro cytotoxicity on normal and cancerous cell lines, respectively. The dose dependent toxicity made it a suitable candidate for various medical applications.

Starch mediated production of silver nanoparticles (Ag-NPs) and their antimicrobial activity against selected pathogens

Nanotechnology has drawn significant attention due to their unique and exceptional applications in recent years. Current scenario protract chemical methods of silver nanoparticle (Ag-NPs) production have noteworthy interest due to their huge demand. The demands of silver nanoparticle keep on increasing day by day. Silver nanoparticles are attracting much interest because of their potent antimicrobial activity. In the present study, silver nanoparticles were produced in aqueous solutions of starch in DMSO and Milli-Q water at high temperature (80°C) under continuous stirring condition. Starch acted as both reducing and stabilizing agents simultaneously for the production of silver nanoparticles. Silver nitrate (AgNO3) of 2mM aqueous solution was used as the metal ion precursor for the fabrication of Ag-NPs under the reaction condition over the period of time. The Plasmon resonance kinetics and their activation energy of nanoparticles were determined by UV – visible spectroscopy. The UV-Vis spectrum revealed the formation of silver nanoparticles by exhibiting the typical surface plasmon absorption maxima at 420 nm. The Milli-Q water solution of starch exhibited better reductive activity than the DMSO solution of starch. The produced silver nanoparticles were subjected to performed antimicrobial activity against selected microbial pathogens. The Milli-Q water solution of starch refereed silver nanoparticles were demonstrated superior antimicrobial activity against Candida albicans than other tested pathogens. The produced silver nanoparticles further to be characterized by SEM, TEM, XRD, AFM etc., to pinpoint the size, morphology and actual constituents responsible for the antibacterial activity. This research opens a new avenue of nanotechnological niche in the field of nanobiotechnology.

Effect of fast electrons on the aggregative stability of aqueous starch solutions

Electron-beam irradiation in air significantly affects the optical absorption and turbidity of aqueous suspensions and hydrogels of starch due to a change in their aggregative stability. The predominant effect of irradiation consists in an increase in the transparency of solutions and the sedimentation of starch. A maximum susceptibility of the starch dispersions and hydrogels to irradiation has been observed at doses below 3 kGy. The effect weakened with the use of a multienergy electron beam because of the appearance of an excess negative charge in micelles, which prevents their coagulation.

Solar-Energy Driven Simultaneous Saccharification and Fermentation of Starch to Bioethanol for Fuel-Cell Applications.

A solar reactor was designed to perform the conversion of starch to ethanol in a single step. An aqueous starch solution (5 wt %) was fed into the reactor bed charged with Baker's yeast (Saccharomyces cerevisiae) and amylase, resulting in approximately 2.5 wt % ethanol collected daily (ca. 25 mL day(-1) ). A significant amount of ethanol (38 g) was collected over 63 days, corresponding to 84 % of the theoretical yield. The production of ethanol without additional energy input highlights the significance of this new process. The ethanol produced was also demonstrated as a potential fuel for direct ethanol fuel cells. Additionally, the secondary metabolite glycerol was fully reduced to a value-added product 1,3-propanediol, which is the first example of a fungal strain (Baker's yeast) converting glycerol in situ to 1,3-propanediol.

Effects of sucrose and vegetable oil on properties of native cassava ( Manihot esculenta Crantz) starch-based edible films

Biopolymer films and coatings from polysaccharides, proteins and lipids, formulated either with one or more components have the potential to control mass transfer and thus extend food shelf life. Due to the increase in the price of starches from traditional sources (such as corn), native or modified cassava starch has been recently considered as an economic alternative for the food industry. In this study, the effects of sucrose and vegetable oil as natural, cheaper and available plasticizer and moisture barrier material, on optical, mechanical and water barrier properties of cassava starch-based films were analyzed. Visual appearance and the polarized light microscopy data revealed that oil made the film opaque, and larger oil droplets were formed as sucrose content increased. The modification of the starch network, when sucrose was used at higher concentrations (15-20%), in combination with oil, weakened mechanical and water barrier properties. The behaviour of sucrose added to aqueous starch solution, in combination with oil, favored a development of larger droplets observed by polar microscopy, and which made the film matrix discontinuous and irregular. The heterogeneity of the film structure made the composite films fragile and facilitated water vapor diffusion. However, the film formulations containing low sucrose concentration (≤ 10 %) and an oil content of 10%, significantly reduced water vapor permeability, in comparison to film without oil. The formulations of composite film with low content of sucrose (≤ 10 %) showed smaller lipidic droplets and a structure more homogeneous by polar microscopy. Film thickness increased with total solid content in film matrix, and this effect was significantly pronounced as higher sucrose content (15-20%) was present with added vegetable oil. In addition to the linking with total solid content, this study revealed that, the thickness of films depends on reordering of molecular chains to form a more compact matrix in composite starch films, and this results in further increase film thickness. The composite films, thicker than the film control, were less cohesive due to less affinity between matrix components, and this resulted in anti-plastifiant behaviour of sucrose. Thus, sucrose used at higher levels, in combination with oil, induced negative effects on mechanical and water barrier properties of polysaccharide film. This study revealed the impact of the nature of molecular interactions on the structural characteristics and functional properties of composite matrix. Keywords : cassava, biofilm, starch, sucrose, lipid

Dielectric relaxations in starch-water solutions

We demonstrate the effect of water-soluble starch on an electrochemical impedance spectrum with the aim of sensing starch concentration in an aqueous solution. The characteristic form of the relative dielectric dispersion curves with respective loss factors was shown to relate to the severity of the starch concentration at a frequency range from 200Hz up to 500kHz. It was also remarkable to recognize that even in a lower frequency regime, for instance from 0.1Hz up to 200Hz, the spectral peaks in the dispersion curves of the dielectric loss factors were observable with separate consecutive relaxation times. According to the results of this study, this clearly demonstrates the reliability of these features when estimating the concentration of starch in aqueous starch solutions.

Effects of sucrose and vegetable oil on properties of native cassava (Manihot esculenta Crantz) starch-based edible films

Biopolymer films and coatings from polysaccharides, proteins and lipids, formulated either with one or more components have the potential to control mass transfer and thus extend food shelf life. Due to the increase in the price of starches from traditional sources (such as corn), native or modified cassava starch has been recently considered as an economic alternative for the food industry. In this study, the effects of sucrose and vegetable oil as natural, cheaper and available plasticizer and moisture barrier material, on optical, mechanical and water barrier properties of cassava starch-based films were analyzed. Visual appearance and the polarized light microscopy data revealed that oil made the film opaque, and larger oil droplets were formed as sucrose content increased. The modification of the starch network, when sucrose was used at higher concentrations (15-20%), in combination with oil, weakened mechanical and water barrier properties. The behaviour of sucrose added to aqueous starch solution, in combination with oil, favored a development of larger droplets observed by polar microscopy, and which made the film matrix discontinuous and irregular. The heterogeneity of the film structure made the composite films fragile and facilitated water vapor diffusion. However, the film formulations containing low sucrose concentration (≤ 10 %) and an oil content of 10%, significantly reduced water vapor permeability, in comparison to film without oil. The formulations of composite film with low content of sucrose (≤ 10 %) showed smaller lipidic droplets and a structure more homogeneous by polar microscopy. Film thickness increased with total solid content in film matrix, and this effect was significantly pronounced as higher sucrose content (15-20%) was present with added vegetable oil. In addition to the linking with total solid content, this study revealed that, the thickness of films depends on reordering of molecular chains to form a more compact matrix in composite starch films, and this results in further increase film thickness. The composite films, thicker than the film control, were less cohesive due to less affinity between matrix components, and this resulted in anti-plastifiant behaviour of sucrose. Thus, sucrose used at higher levels, in combination with oil, induced negative effects on mechanical and water barrier properties of polysaccharide film. This study revealed the impact of the nature of molecular interactions on the structural characteristics and functional properties of composite matrix.

Bicomponent Solutions of Food Polysaccharide and Edible Films on Their Basis

The study of the rheological properties of aqueous solutions of corn starch (CS) blends with sodium alginate (SA) and agar-agar (AA) as well as the physical and mechanical properties of bicomponent films on their basis has been carried out. The data show that adding of both polymers to starch solution causes an increase in viscosity which is higher in the case of SA. Activation energy for viscosity flow of solutions of CS blended with SA has minimum value at CS:SA ratio = 98:2. The above mentioned dependence is not typical for AA, as flow activation energy in this case raises steadily with the growth of AA content in the solution, like viscosity of the CS:AA. The extreme behavior of polymer blends with low content of one of the polymers is described in terms of mutual solubility or thermodynamic compatibility. There is a tendency that mechanical properties and water solubility increase with the increasing of SA and AA polymers in corn starch matrix. Obtained data evidence the benefits of bicomponent films production instead of starch-based films.

Studies About the Solvent‐Dependent Substitution Pattern of Starch Acetates

Starch acetates bearing the ester moiety predominantly at position 2 of the anhydroglucose unit (AGU) could be synthesized by converting starch with acetic anhydride and imidazole in dimethyl sulfoxide (DMSO). Degraded starch (weight average molar mass, < 16 460 g mol−1) is additionally acetylated at position 6 exceeding a total degree of substitution (DS) of 0.5. Increasing the concentration of starch up to 50 wt% leads to higher partial DS at position 6 under comparable reaction conditions. Using molten imidazole as solvent, an initial regioselective 6‐O‐acylation is achieved. At higher DS values (>0.3), a random distribution of the substituents appears. The substitution pattern can be revealed precisely by means of 13C and 1H NMR spectroscopy after perpropionylation. Hydrolytic stability of a selected 2‐O‐acetyl starch in aqueous solution is evaluated by time‐dependent capillary viscosimetry.

Ozone oxidation of cassava starch in aqueous solution at different pH

Ozone is a more powerful oxidant than common oxidising agents, such as sodium hypochlorite and hydrogen peroxide. It is considered as a safer starch modification method for both consumers and the environment. However, few studies have investigated the changes in starch properties associated with ozone treatment, particularly when applied in aqueous solution. This work aimed to evaluate the carbonyl and carboxyl contents, the X-ray diffraction patterns, the spectrum profiles of Fourier transform infrared spectroscopy, the pasting properties and the surface morphology of ozone-oxidised cassava starch during 60min under different pH (3.5, 6.5 and 9.5) at 25°C. The pH 6.5 and 9.5 seemed to favour the cross-linking between the depolymerised starch molecules during ozonation. The pH 3.5 was more effective in reducing the peak viscosity, breakdown, setback and final viscosity of cassava starch during ozonation in aqueous solution. No differences in the granule surface morphology were observed in the ozone-treated cassava starches compared to native starch.

Acid monolayer functionalized iron oxide nanoparticles as catalysts for carbohydrate hydrolysis

Superparamagnetic iron oxide nanoparticles were functionalized with a quasi-monolayer of 11-sulfoundecanoic acid and 10-phosphono-1-decanesulfonic acid ligands to create separable solid acid catalysts. The ligands are bound through carboxylate or phosphonate bonds to the magnetite core. The ligand-core bonding surface is separated by a hydrocarbon linker from an outer surface with exposed sulfonic acid groups. The more tightly packed monolayer of the phosphonate ligand corresponded to a higher sulfonic acid loading by weight, a reduced agglomeration of particles, a greater tendency to remain suspended in solution in the presence of an external magnetic field, and a higher catalytic activity per sulfonic acid group. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), and dynamic light scattering (DLS). In sucrose catalysis reactions, the phosphonic–sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic–sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. The activity of the acid-functionalized nanoparticles was compared to the traditional solid acid catalyst Amberlyst-15 for the hydrolysis of starch in aqueous solution. Catalytic activity for starch hydrolysis was in the order PSNPs > CSNPs > Amberlyst-15. Monolayer acid functionalization of iron oxides presents a novel strategy for the development of recyclable solid acid catalysts.

Neuronal toxicity of biopolymer-template synthesized ZnO nanoparticles

Objective(s): A simple and green method was developed for preparing zinc oxide nanoparticles (ZnO-NPs) in aqueous starch solutions. Starch was used as a stabilizer to control of the mobility of zinc cations and then control growth of ZnO-NPs prepared via a sol-gel method. Because of the special structure of the starch, it permits termination of the particle growth. Materials and Methods: The dried gel was calcined at different temperatures of 400, 500, 600, and 700 °C. The prepared ZnO-NPs were characterized by different techniques such as X-ray diffraction analysis (XRD), transmittance electron microscopy (TEM), and UV-Vis absorption. Results: The XRD results displayed hexagonal (wurtzite) crystalline structure for prepared ZnO nanoparticles with mean sizes below than 50 nm. In vitro cytotoxicity studies on neuro2A cells showed a dose dependent toxicity with non-toxic effect of concentration below 6 µg/mL. Conclusion: The results showed that starch is an eco-friendly material that can be used as a stabilizing agent in the sol-gel technique for preparing of ZnO-NPs in a large scale.

Waterborne polyurethane based starch containing materials: Preparation, properties and study of degradability

Abstract New starch-containing aqueous anionic polyurethane dispersions (APU/St) were prepared by the introduction of an aqueous starch solution into an anionic oligourethane solution and by the combination of the chain extension and dispersion stages. A fundamental difference between the APU/St dispersions and mechanical mixtures of anionic polyurethane dispersions and starch (APU + St), which manifests itself in a high aggregate stability and ability to form solid films, has been proved. APU/St based films display higher tensile strength in comparison with St and are characterized by increased values of elongation at break, degree of hydrophilicity, and significantly enhanced ability to undergo an acid/alkaline hydrolysis compared with the APU matrix. The adhesion of microorganisms Bacillus subtilis to the APU/St surface, which is the first step and determining factor of biodegradation, exceeds those of the APU matrix. The introduction of St into the APU structure resulted in the formation of amorphous polymer–polymer microdomains, i.e. an integrated system formed due to the presence of both the covalent and the hydrogen bonds between its ingredients. This predetermines the degradation of the APU/St systems as a whole, unlike the mixed APU + St films.

The effect of laser repetition rate on the LASiS synthesis of biocompatible silver nanoparticles in aqueous starch solution

Laser ablation-based nanoparticle synthesis in solution is rapidly becoming popular, particularly for potential biomedical and life science applications. This method promises one pot synthesis and concomitant bio-functionalization, is devoid of toxic chemicals, does not require complicated apparatus, can be combined with natural stabilizers, is directly biocompatible, and has high particle size uniformity. Size control and reduction is generally determined by the laser settings; that the size and size distribution scales with laser fluence is well described. Conversely, the effect of the laser repetition rate on the final nanoparticle product in laser ablation is less well-documented, especially in the presence of stabilizers. Here, the influence of the laser repetition rate during laser ablation synthesis of silver nanoparticles in the presence of starch as a stabilizer was investigated. The increment of the repetition rate does not negatively influence the ablation efficiency, but rather shows increased productivity, causes a red-shift in the plasmon resonance peak of the silver–starch nanoparticles, an increase in mean particle size and size distribution, and a distinct lack of agglomerate formation. Optimal results were achieved at 10 Hz repetition rate, with a mean particle size of ~10 nm and a bandwidth of ~6 nm ‘full width at half maximum’ (FWHM). Stability measurements showed no significant changes in mean particle size or agglomeration or even flocculation. However, zeta potential measurements showed that optimal double layer charge is achieved at 30 Hz. Consequently, Ag–NP synthesis via the laser ablation synthesis in solution (LASiS) method in starch solution seems to be a trade-off between small size and narrow size distributions and inherent and long-term stability.

Influence of Physical Treatments on the Potato Starch Granules Micro- and Ultrastructure

In this research, potato starch was subjected to physical treatments in order to analyse the changes at the micro- and ultrastructural levels and finally to identify the optimal conditions for disintegrating the starch granules. For the analysis, 10% aqueous solutions of potato starch were treated with a) microwaves; b) heat and c) heat combined with ultrasounds. For each treatment type, the duration was 5 minutes, excepting the microwave treatment, where the time was 1 and 5 minutes; heat power varied from 180W to 900W at the tests with microwave, temperature varied between 65C and 100oC in the thermal experiments and at the thermal analysis combined with ultrasounds temperature had values between 35oC and 85oC. The effect of these treatments was analysed using microscopic techniques (optical and scanning electron microscopy) in order to describe the morphological and micro- and ultrastructural modifications of the starch granules. Results indicated that the morphological and microstructural differences mostly depend on the chosen treatment and on the working conditions. The microwaves treatment was shown to be more effective on disintegrating the starch granule than the thermal action combined with ultrasounds or the thermal treatment alone. Starch granule was cracked at the heat power of 180W even after 1 minute of treatment; after 5 minutes, the gel-like structure was clearly formed for all the granules. Ultrasounds also modified the granule structure by cracking. High temperature (minimal 85oC) was essential for the propagation of ultrasounds or for the thermal treatment in order to assure the efficacy of the physical treatments on the granule. o

Ozonation of corn and potato starch in aqueous solution: effects on the thermal, pasting and structural properties

SummaryStarch–water suspensions were exposed to ozone gas for 1 h at 5 °C. The concentration of dissolved ozone gas in the suspension was kept at 4.2 mg ozone/L−1 water. Polarised light and scanning electron microscope (SEM) were used to examine the birefringence and surface characteristics of the samples, respectively. A differential scanning calorimeter (DSC) was used to measure the gelatinisation properties, while a rapid visco analyser (RVA) was used to examine pasting properties. The structure of corn and potato starch showed very little change after treatment with ozonated water. The DSC gelatinisation temperatures (i.e. onset, peak and conclusion) of starch samples increased as a result of ozonation. However, a decrease in gelatinisation enthalpies was observed for ozonated starch samples. A dramatic decrease in the RVA viscosities of ozonated starch samples was observed after ozonation, which are explained by the partial cleavage of the glycosidic linkages in the starch granules during ozonation.

Preparation of aqueous dispersions of coenzyme Q10 nanoparticles with amylomaize starch and its dextrin

An aqueous dispersion of CoQ10 nanoparticles could be prepared by using amylomaize starch or its dextrin (average DP 311). CoQ10 (100 mg dry solids) was dispersed in aqueous starch or dextrin solution (500 mg/5 mL) at 60–80 °C for 3 days, and then the solids were isolated by centrifuging in the dispersion (25,000×g, 30 min). The isolated particles consisted of CoQ10 and starch at an approximate weight ratio of 2:1. The presence of V-amylose complex with CoQ10 was confirmed under differential scanning calorimetery (DSC), but most of the CoQ10 in the particles existed as crystalline aggregates. The isolated particles, initially ranged in micrometer, could be re-dispersed in water at nano-sizes by treating with a mild ultrasonication. The aqueous dispersions of CoQ10 nanoparticles (100 mg/100 g) exhibited zeta potentials of −33.9 and −51.1 mV, respectively for starch and dextrin dispersions, and remained homogeneous for more than 3 weeks without forming precipitates during an ambient storage.

Application of the Multisolute Osmotic Virial Equation to Solutions Containing Electrolytes

The prediction of multisolute solution behavior of solutions containing electrolytes is important in many areas of research, including cryopreservation. In this study, the use of a novel form of the osmotic virial equation for multisolute solutions containing an electrolyte is investigated and compared to a rigorous electrolyte solution theory, the Pitzer-Debye-Huckel equation. For aqueous solutions containing a small molecule (either dimethyl sulfoxide or glycerol) and sodium chloride, the multisolute osmotic virial equation, which utilizes only two parameters to capture the electrolyte solution behavior, is shown to be as accurate as the Pitzer-Debye-Huckel equation, which utilizes six empirical parameters and multiple functions to capture the electrolyte solution behavior. In addition, an approach based on the multisolute osmotic virial equation to investigate the effect of electrolyte concentration on macromolecule solution behavior is presented and applied to aqueous solutions of hydroxyethyl starch and sodium chloride. The multisolute osmotic virial equation is shown to be an accurate, straightforward predictive solution theory for important multisolute solutions containing electrolytes.

Formation mechanism of novel two-dimensional single crystalline dendritic copper plates in an aqueous environment

This paper reports on the creation of a unique form of single crystalline two-dimensional (2-D) copper microdendritic plates and proposes a new crystal growth mechanism in an aqueous environment. The crystals are formed via reduction of CuSO4 with starch in aqueous solution. The 2-D crystals are typically ∼300nm thick and ∼50μm wide, and consist of rhombic petals of (111) planar orientation. The plates are found to nucleate at the centre in polyhedral shapes and grow outwards along zigzag growth paths along the 〈112¯〉 directions. Formation of such a crystal morphology is attributed to three different growth controlling criteria. The formation of polyhedral crystalline nuclei is controlled by the Gibbs–Wulff theorem, driven by the need to minimize the total surface energy for nucleation; growth of the crystal to form a 2-D rosette morphology is controlled by the planar expansion kinetics of low surface energy crystallographic planes; the zigzag dendritic growth pattern is dictated by the Cu2+ concentration gradient at the crystal growth fronts in the solution.