Starch-based nano-biocomposites

Preparation of starch nanoparticles loaded with quercetin using nanoprecipitation technique

Nanoparticles of starches from different botanical origin were prepared by nanoprecipitation using 0.1M hydrochloric acid as non-solvent. The morphology and the particle size were analyzed using field emission scanning electron microscopy and dynamic light scattering. The nanoparticles were spherical and their sizes vary depending on the origin and the concentration of the starch solution. Starch nanoparticles loaded with quercetin were prepared. In-vitro release studies of the quercetin from the starch nanoparticles were performed in 35% ethanol as a release medium. The starch origin affects the quercetin loading percentage, the release kinetics and the antioxidant activity of the produced nanoparticles. The starch-quercetin nanoparticles from cereal origin showed the lowest loading percentage and the lowest fraction released of quercetin in comparison with nanoparticles from tuber and legume origin. The release kinetics seem to be controlled mainly by Fickian diffusion which have been revealed fitting the release data to the Peppas-Sahlin model.

Tunable d-Limonene Permeability in Starch-Based Nanocomposite Films Reinforced by Cellulose Nanocrystals

In order to control d-limonene permeability, cellulose nanocrystals (CNC) were used to regulate starch-based film multiscale structures. The effect of sphere-like cellulose nanocrystal (CS) and rod-like cellulose nanocrystal (CR) on starch molecular interaction, short-range molecular conformation, crystalline structure, and micro-ordered aggregated region structure were systematically discussed. CNC aspect ratio and content were proved to be independent variables to control d-limonene permeability via film-structure regulation. New hydrogen bonding formation and increased hydroxypropyl starch (HPS) relative crystallinity could be the reason for the lower d-limonene permeability compared with tortuous path model approximation. More hydrogen bonding formation, higher HPS relative crystallinity and larger size of micro-ordered aggregated region in CS0.5 and CR2 could explain the lower d-limonene permeability than CS2 and CR0.5, respectively. This study provided new insight for the control of the flavor release from starch-based films, which favored its application in biodegradable food packaging and flavor encapsulation.

Application of ultrasonic irradiation as a benign method for production of glycerol plasticized-starch/ascorbic acid functionalized MWCNTs nanocomposites: Investigation of methylene blue adsorption and electrical properties

A solution mixing and ultrasonic dispersion method as a green, the fast, inexpensive and effective technique was utilized to prepare glycerol plasticized-starch (GPS)/ascorbic acid (AA)-MWCNTs nanocomposites (NCs) via the introduction of various amounts of AA-MWCNTs (3, 6 and 9wt%) as filler into GPS matrix. The GPS was synthesized by addition of glycerol (50%) as a plasticizer to starch which enhances its flexibility. Characterization of the obtained GPS/AA-MWCNTs NCs was accomplished by different techniques. The optimum filler content for the generation of fine electrical conductivity and good mechanical properties was found to be about 3wt%. The distribution of AA-MWCNTs at the low content (3wt%) in the GPS matrix was better due to the strong linkage between nanofiller and GPS in GPS/AA-MWCNTs NC. The results of adsorption studies showed that the fabricated NC can be a good adsorbent for removal of methylene blue (MB) dye from aqueous solutions.

Effect of Addition of Antioxidant Flaxseed Polypeptide on the Rheological Properties of Native Maize Starch

Effects of adding antioxidant flaxseed peptides (FP) on rheological properties of native maize starch (NMS) were investigated using temperature sweep and frequency sweep tests. The NMS concentration of 15 % (w/w) and FP concentrations of 0.2–1.0 % (w/w) were used. The FP samples were prepared by controlled hydrolysis flaxseed protein isolate with pepsin. The highest DPPH radical scavenging activity (53.25 %) was achieved at 22 % of hydrolysis. The onset gelatinization temperature (Tonset) increased from 67°C to 76°C when the 1 % FP was present in the NMS–FP mixture. The storage modulus (G′) decreased significantly in the presence and increased in concentration of FP. The variation ofG′and loss modulus (G″) of NMS–FP mixtures with angular frequency was fitted well (R2>0.97) Power law type models. The consistency coefficient (K′andK″) decreased in the presence and increased in the concentration of FP. While then′increased with the presence FP, then″decreased. The NMS–FP mixtures produced physical gels (G′>G″). NMS-FP mixtures showed non-Newtonian shear thinning behavior in steady shear flow.

New technique in starch nanoparticles synthesis

Starch nanoparticles (StNPs) were previously prepared using severe mechanical, physical and/or chemical conditions that takes too long time to produce a little yield of uncontrolled large size of StNP. The current work presents a new technique for the synthesis of StNPs based on the combination between sodium hydroxide and glycerol in aqueous medium during the synthesis process while the precipitation of the StNPs is performed under homogenization at ambient conditions. The new technique is based on three assumptions: 1) the dual impact of sodium hydroxide and glycerol on the swelling and gelatinization of starch as a pre-stage of the synthesis of (StNPs1), 2) the dual impact of glycerol and cooking of starch on the swelling and gelatinization of starch as a pre-stage of the formation of (StNPs2), and 3) the precipitation under homogenization at ambient conditions and its effect on breaking the H- bonds of the starch molecule in both StNPs1 and StNPs2. The importance of this technique arises from the ease of the process, the eco-friendly chemicals and the combination between the mechanical and chemical processes. NS (native starch), StNPs1 and StNPs2 were characterized using FTIR, XRD, TGA and TEM. TEM of StNPs1 showed a well-defined round particles uniformly distributed with size of about 62.5nm. StNPs2 showed a non-specific shape starch particles.

Effect of nanocellulose as a filler on biodegradable thermoplastic starch films from tuber, cereal and legume

Starches from different vegetal sources (tuber, cereal and legume) were plasticized with an invariant glycerol content and reinforced with cellulose nanocrystals by solution casting method. The influence of both, starch nature and filler amount, in the crystallinity and the extension of plasticization have been analyzed by X-ray diffraction. Thermoplastic starches (TPS) morphologies were obtained by scanning electron microscopy. Mechanical properties and thermal stability were analyzed by dynamomechanical and thermogravimetric analysis. Water absorption evolution was studied as well. A major extension in plasticization (high amylopectin starches) led to matrices with large starch-rich domains, a good thermal stability and resistance to water absorption but low stiffness. The incorporation of cellulose nanoparticles favoured plasticization and increased the rigidity in TPS films, as well as the thermal stability and moisture resistance. The aim of this work was to obtain bio-based thermoplastic starch films for replacing petroleum-derived ones in packaging industry, especially for short-life applications.

Catalytic Transesterification of Starch with Plant Oils: A Sustainable and Efficient Route to Fatty Acid Starch Esters

The transesterification of maize starch with olive oil or high oleic sunflower oil was studied under homogeneous conditions in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst. Most importantly, this method used two renewable resources directly, without any pretreatment or derivatization, for the synthesis of polymeric materials with desirable properties. Moreover, the solvent, oils, and catalyst could be recovered through facile work-up and reused for further modifications. The obtained fatty acid starch esters (FASEs) were highly soluble in common organic solvents and were thoroughly characterized. Degrees of substitution (DS) were calculated using ³¹ P NMR spectroscopy, and DS values of approximately 1.3 were obtained. Differential scanning calorimetry analysis revealed thermal transitions of the modified starches at approximately 80-90 °C. Films were produced from these FASEs, and their hydrophobic surfaces were characterized using contact-angle measurements. Furthermore, mechanical properties were examined using tensile strength measurements and showed approximately 40 and 80 % elongation at break for modified maize starch and modified amylose from maize, respectively.

Effect of Elongational Flow and Polarity of Organomodified Clay on Morphology and Mechanical Properties of a PLA Based Nanobiocomposite

In biodegradable polymer world nanobiocomposites represent a new group of materials filled with inert nanoparticles that shows very interesting properties and the biodegradability of the matrix. In this work we have studied the effect of the polarity of the organomodified montmorillonite and of the elongational flow on the morphology and the rheological and mechanical properties of a new nanobiocomposite with a matrix of biodegradable PLA based blend. The elastic modulus enhances in presence of the nanofiller and this increase is larger and larger with the increment of the orientation. The tensile strength does not show any significant change at the same level of orientation. Moreover, a brittle-to-ductile transition is observed in the anisotropic sample and this effect is again more evident for the nanocomposite. The raise of the interlayer distance is higher for the more polar montmorillonite, even if the two nanocomposites show about the same final interlayer distance and morphology. Some exfoliation is also observed as a result of the application of the elongational flow.