Synthesis and characterization of carboxymethyl potato starch and its application in reactive dye printing

Carboxymethyl potato starch (CMPS) was synthesized with a simple dry and multi-step method as a product of the reaction of native potato starch and monochloroacetic acid in the presence of sodium hydroxide. The influence of the molar ratio of sodium hydroxide to anhydroglucose unit, the volume of 95% (v/v) ethanol, the rotation rate of motor driven stirrer and the reaction time for degree of substitution (DS) were evaluated. The product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). FTIR spectrometry showed new bonds at 1618 and 1424cm(-1) when native starch underwent carboxymethylation. SEM pictures showed that the smooth surface of native starch particles was mostly ruptured. XRD revealed that starch crystallinity was reduced after carboxymethylation. The viscosity of the mixture paste of carboxymethyl starch and sodium alginate (SA) was measured using a rotational viscometer. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with SA. And the results indicated that the mixed paste could partially replace SA as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing.     

The effect of lintnerisation on wheat and potato starch granules

Wheat and potato starches were hydrolysed with 2·2 n hydrochloric acid at 35°C for a period of time up to 15 days. The residues (lintnerised starches) were washed and freeze dried, and studied by differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), small-angle light scattering (SALS), small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). These techniques showed that profound changes took place in the first day of hydrolysis (during which time the extent of hydrolysis was 7·7% for potato starch and 12·5% for wheat starch). In particular, the gelatinisation enthalpy (ΔH) decreased, the X-ray crystallinity increased and the SANS and SAXS peaks (indicative of a regular spacing between crystalline and amorphous regions) virtually disappeared. The reduction in ΔH is surprising and is discussed at length. It was also shown that freeze drying results in a considerable lowering of the gelatinisation temperature of potato starch (and also of ΔH) while that of wheat starch is only slightly affected.     

Modified natural halloysite/potato starch composite films

Halloysite/potato starch composites were prepared by adding modified natural halloysite nanotubes into potato starch matrices to reenforce the mechanical properties of potato starch films. The halloysite/potato starch films were characterized by X-ray diffraction, scanning electron microscope and infrared spectrometry. Meanwhile, the mechanical properties and transparency of the films were studied. The results show that the modified halloysite nanotubes can be well distributed in the starch matrix and thus the tensile strength of the films was clearly enhanced. The flexibility of the films could be improved through adding glycerol although at the cost of reducing tensile strength. But incorporation of PVA could further improve the tensile strength of the halloysite/potato starch films.     

Lipase-coupling esterification of starch with octenyl succinic anhydride

Enzymatic modification of starch was conducted by lipase-coupling esterification with octenyl succinic anhydride (OSA). Parameters affecting the esterification were systematically studied. Products were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction, differential scanning calorimetry (DSC) and viscosity analysis (VA). Optimum condition for lipase-coupling OSA starch preparation was as follows: starch pretreatment at 65 °C for 15 min, starch concentration 35%, amount of lipase and OSA, 0.6% and 3%, reaction pH, temperature and time, 8.0, 40 °C and 30 min respectively, which resulted in 0.0195 of the degree of substitution and 84.05 ± 2.07% of the reaction efficiency. FT-IR spectroscopy confirmed the formation of OSA starch. SEM and X-ray diffraction showed apparent surface change, but no crystalline change. DSC and VA results indicated the synthesized OSA starch gelatinized rapidly with high viscosity. Attractively, reaction time drastically reduced to 30 min, showing vast potential for scale production of OSA starch.     

Origin of defects in assembled supramolecular structures of sweet potato starches with different amylopectin chain-length distribution

A combined approach of fluorophore-assisted capillary electrophoresis (FACEL), high-sensitivity differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), and light (LM) and scanning electron microscopy (SEM) was applied to study the effects of changes in amylopectin chain-length distribution on the assembly structures of sweet potato starches with similar amylose levels. It was shown that unlike ordinary sweet potato starch, starch extracted from Quick Sweet cultivar of sweet potato had anomalous high level of amylopectin chains with a degree of polymerization (DP) 6–12. Joint analysis of the obtained data revealed that amylopectin chains with DP 10–24 are, apparently, the dominant material for the formation of supramolecular structures in starch granules. In contrast, amylopectin chains with DP < 10 facilitated the formation of defects within crystalline lamellae. An increase in relative content of amylopectin chains with DP < 10 is accompanied by the correlated structural alterations manifested at all levels of starch granule organization (crystalline lamellae, amylopectin clusters, semi-crystalline growth rings, and granule morphology). Thus, the short amylopectin chains with DP < 10 were considered as an origin of the defectiveness in starch supramolecular structures.     

Influence of cross-linked potato starch treated with POCl3 on DSC, rheological properties and granule size

Differential scanning calorimetry (DSC), rheological measurements and granule size analyses were performed to characterize the influence of phosphorylation substitution levels on the properties of cross-linked potato starch. Phosphorus oxychloride (POCl₃) was used to produce the cross-linked potato starch. The levels of the reagent used for the reaction ranged between 40 and 5000 ppm (dwb). Storage (G′) and loss (G″) moduli were measured for a 5% (w/w) gelatinized starch dispersion stored at 20 °C for 24 h after heating at 85 °C for 30 min. The samples from 80 to 500 ppm were recognized as ‘strong gel'systems, whereas native potato starch showed ‘weak gel'behavior. Steady shear and dynamic viscoelastic properties of gelatinized starch dispersion were compared. Furthermore, granule mean diameter was measured by laser scattering for a 1% (w/w) dispersion heated at 85 °C for 30 min. The granules in the 100 ppm sample swelled to a maximum of about 2.6 times the native starch granule mean diameter.     

Phosphorylation of potato starch and its electrorheological suspension

Highly substituted potato starch phosphate (HPSP) particles were synthesized via an esterification process of potato starch with a mixture of several different concentrations of disodium hydrogen phosphate and sodium hydrogen phosphate. These particles were characterized via thermogravimetric analysis, scanning electron microscope, and inductively coupled plasma mass spectrometer. The electrorheological (ER) fluid was prepared by dispersing these HPSP particles in nonconducting silicone oil, and their ER properties were investigated. The HPSP particle-based ER fluid exhibited typical ER responses with a nonzero yield stress under an applied electric field. We examined the yield stresses for the potato starch-based anhydrous ER system by varying the degree of phosphate substitution and found that the higher polarization induced by the external electric field strength resulted in the higher values of yield stresses and shear stresses.     

State diagram of potato starch–water mixtures treated with high hydrostatic pressure

Potato starch–water mixture was treated with high hydrostatic pressure (HHP) of up to 1.2 GPa, and effect of starch content (10–70% (w/w)) on HHP-gelatinization was investigated by differential scanning calorimetry (DSC). Depending on the treatment pressure and potato starch content, DSC thermograms showed decrease in enthalpy change of heat gelatinization reflecting the progress of HHP-gelatinization and increase in enthalpy change of re-gelatinization of retrograded starch. From the viewpoint of the enthalpy changes, physically modified state of HHP-treated potato starch–water mixtures was classified as follows: no change, partial gelatinization, complete gelatinization, partial gelatinization and retrogradation, and complete gelatinization and retrogradation. A state diagram of potato starch–water mixtures (treatment pressure vs. starch content) was presented.     

Preparation of cassava starch grafted with polystyrene by suspension polymerization

Cassava starch grafted with polystyrene (PS-g-starch) copolymer was synthesized via free-radical polymerization of styrene by using suspension polymerization technique. Potassium persulfate (PPS) was used as an initiator and water was used as a medium. The graft copolymer was characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, X-ray diffraction and scanning electron microscopy. The sub-micron spherical beads of PS were observed on the surface of starch granules. SEM micrographs showed porous patches of PS adhering on the starch granules after Soxhlet extraction. FTIR spectra also indicated the presence of PS-g-starch copolymer. XRD analysis exhibited insignificant changes in crystalline structure and degree of crystallinity. The effects of starch:styrene weight ratio, amount of PPS, reaction time and reaction temperature on the percentage of grafting – G (%), were investigated. G (%) increased with increasing starch content. Other variables showed their own individual optimal values. The optimum condition yielding 31.47% of G (%) was derived when the component ratio was 1:3 and reaction temperature and time were 50 °C and 2 h, respectively. Graft copolymerization did not change granular shape and crystallinity of starch. This study demonstrated the capability of polymerization of styrene monomer on the granular starch without emulsifier and the synthesis of graft copolymer without gelatinization of starch.     

Nitrogen Source Regulation of Growth and Photosynthesis in Beta vulgaris L

A chimeric gene containing the patatin promoter and the transit-peptide region of the small-subunit carboxylase gene was utilized to direct expression of Escherichia coli glycogen synthase (glgA) to potato (Solanum tuberosum) tuber amyloplasts. Expression of the glgA gene product in tuber amyloplasts was between 0.007 and 0.028% of total protein in independent potato lines as determined by immunoblot analysis. Tubers from four transgenic potato lines were found to have a lowered specific gravity, a 30 to 50% reduction in the percentage of starch, and a decreased amylose/amylopectin ratio. Total soluble sugar content in these selected lines was increased by approximately 80%. Analysis of the starch from these potato lines also indicated a reduced phosphorous content. A very high degree of branching of the amylopectin fraction was detected by comparison of high and low molecular weight carbohydrate chains after debranching with isoamylase and corresponding high-performance liquid chromatography analysis of the products. Brabender viscoamylograph analysis and differential scanning calorimetry of the starches obtained from these transgenic potato lines also indicate a composition and structure much different from typical potato starch. Brabender analysis yielded very low stable paste viscosity values (about 30% of control values), whereas differential scanning calorimetry values indicated reduced enthalpy and gelatinization properties. The above parameters indicate a novel potato starch based on expression of the glgA E. coli gene product in transgenic potato.     

Preparation and characterization of gelatinized granular starches from aqueous ethanol treatments

In order to modify the properties of native starch granules, the formation of gelatinized granular forms (GGS) from normal, waxy, and high amylose maize, as well as potato and tapioca starches was investigated by treating granules with aqueous ethanol at varying starch:water:ethanol ratios and then heating in a rotary evaporator to remove ethanol. The modified starches were characterized using bright field, polarized and electron microscopy. Short/long range molecular order and enthalpic transitions on heating were also studied using infrared spectroscopy, X-ray diffractometry and differential scanning calorimetry respectively. A diffuse birefringence pattern without Maltese cross was observed for most GGS samples. Treatment with aqueous ethanol resulted in starch-specific changes in the surface of granules, most noticeably swelling and disintegration in waxy maize, surface wrinkling in normal maize and tapioca, swelling and opening-up in potato starches, and swelling and bursting in high amylose maize. The ratio of ethanol to water at which original granular order was disrupted also varied with starch type. GGS had less short range molecular order than native granules as inferred by comparing 1047/1022 wave number ratio from infrared spectroscopy. Similarly, A- and B-type diffraction reflections were either reduced or completely lost with evolution of V-type patterns in GGS.     

Rheological and structural properties of starches from γ-irradiated and stored potatoes

Starch was extracted from irradiated and stored potato tubers and the properties were compared to CIPC (chlorpropham) treated tubers. The granule properties and dynamic viscoelasticity in temperature ramp and frequency sweep modes were studied while heating the samples. Starch structural characteristics were investigated by high performance anion exchange chromatography (HPAEC) and Fourier transform infrared spectroscopy (FTIR). Gamma-irradiation of potato tubers at a dosage of 0.1 kGy induced some degradation of starch molecules, resulting in earlier swelling of starch granules, and greater extents of amylose and total carbohydrate leaching. The early swelling phenomenon was also enhanced with tuber storage time. The retrogradation rate and extent for a concentrated starch gel also increased with tuber storage time whereas γ-irradiation delayed the gel retrogradation. Sprout inhibiting methods could be selected based on the specific processing and texture requirements of the end products.     

A new insight into the gelatinization process of native starches

The gelatinization characteristics of seven different food starches (regular corn, high-amylose corn, waxy corn, wheat, rice, potato, and tapioca) were investigated. Each starch sample type was heated to 35, 40, 45, etc. up to 85 °C at 5 °C intervals, and freeze-dried. The treated samples were analyzed using light microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and high-performance size exclusion chromatography (HPSEC). When heated, granules underwent structural changes prior to the visible morphological changes that took place during gelatinization. The nature of these structural changes depended on starch type. These results indicate that the starch gelatinization process is more complex than a simple granular order-to-disorder transition.     

Synthesis, analysis and reduction of 2-nitropropyl starch

Granular 2-nitropropyl potato starch was synthesized by reaction with 2-nitropropyl acetate in an aqueous suspension. Nitroalkylation occurs preferentially with the amylose fraction of potato starch, as was confirmed by leaching experiments and digestion of the modified starch with alpha-amylase. The 2-nitropropyl substituent is a mixture of the nitroalkane and nitronic acid tautomer. Some grafting occurs and to a lesser extent additional reactions (formation of carbonyls and oximes) of the nitro group take place. After catalytic hydrogenation of water soluble 2-nitropropyl starch only a small amount of the nitro functionality was reduced to the corresponding amine. Reduction of granular 2-nitropropyl starch with sodium dithionite did not go to completion and led to a complex mixture of starting material, several intermediates and side products (for example sulfamates).     

ENHANCED BIOSYNTHESIS OF POLY(3-HYDROXYBUTYRATE) FROM POTATO STARCH BY Bacillus cereus STRAIN 64-INS IN A LABORATORY-SCALE FERMENTER

To decrease the polyhydroxyalkanoate (PHA) production cost by supplying renewable carbon sources has been an important aspect in terms of commercializing this biodegradable polymer. The production of biodegradable poly(3-hydroxyalkanoates) (PHA) from raw potato starch by the Bacillus cereus 64-INS strain isolated from domestic sludge has been studied in a lab-scale fermenter. The bacterium was screened for the degradation of raw potato starch by a starch hydrolysis method and for PHA production by Nile blue A and Sudan black B staining. Shake-flask cultures of the bacterium with glucose [2% (w/v)] or raw potato starch [2% (w/v)] produced PHA of 64.35% and 34.68% of dry cell weight (DCW), respectively. PHA production was also carried out in a 5-L fermenter under control conditions that produced 2.78 g/L of PHA and PHA content of 60.53% after 21 hr of fermentation using potato starch as the sole carbon source. Gas chromatography–mass spectroscopy (GC-MS) analyses confirmed that the extracted PHA contained poly(3-hydroxybutyrate) (PHB) as its major constituent (>99.99%) irrespective of the carbon source used. The article describes, for what we believe to be the first time, PHB production being carried out without any enzymatic or chemical treatment of potato starch at higher levels by fermentation. More work is required to optimize the PHB yield with respect to starch feeding strategies.     

新型淀粉基全生物降解薄膜的研究

以玉米淀粉为主要原料,研究了蚋米SiO_2改性淀粉薄膜的最佳分散处理工艺,并通过测定样品的红外吸收光谱、X-射线衍射图和扫描电镜照片对该膜的结构进行了分析。结果表明:纳米SiO_2的最佳分散工艺为向2g纳米SiO_2的分散液中加入0.015g聚丙烯酰胺(PA)后,先用机械力研磨分散1h,然后置入淀粉-聚乙烯醇(ST-PVA)共混液中;纳米SiO_2在淀粉和聚乙烯醇分子间形成了均一致密的交联网状结构;所制备薄膜的各项性能均得到大幅度提高,其中拉伸强度可达34.82Mpa,断裂伸长率为331%,达到国标GB 4456—84所规定的标准。     

Physico-chemical and morphological characteristics of New Zealand Taewa (Maori potato) starches

The physico-chemical, morphological, thermal, pasting, textural, and retrogradation properties of the starches isolated from four traditional Taewa (Maori potato) cultivars (Karuparera, Tutaekuri, Huakaroro, Moemoe) of New Zealand were studied and compared with starch properties of a modern potato cultivar (Nadine). The relationships between the different starch characteristics were quantified using Pearson correlation and principal component analysis. Significant differences were observed among physico-chemical properties such as phosphorus content, amylose content, swelling power, solubility and light transmittance of starches from the different potato cultivars. The starch granule morphology (size and shape) for all the potato cultivars showed considerable variation when studied by scanning electron microscopy and particle size analysis. Starch granules from Nadine and Moemoe cultivars showed the presence of large and irregular or cuboid granules in fairly high number compared with the starches from the other cultivars. The transition temperatures (T_o; T_p; T_c) and the enthalpies (ΔH_gel) associated with gelatinization suggested differences in the stability of the crystalline structures among these potato starches. The Moemoe starch showed the lowest T_o, while it was higher for Tutaekuri and Karuparera starches. Pasting properties such as peak, final and breakdown viscosity and texture profile analysis (TPA) parameters of starch gels such as hardness and fracturability were found to be higher for Nadine and Huakaroro starches. The Nadine and Huakaroro starch gels also had lower tendency towards retrogradation as evidenced by their lower syneresis (%) during storage at 4 °C. Principal component analysis showed that the Tutaekuri and Nadine cultivars differed to the greatest degree in terms of the properties of their starches.     

Simple organocatalytic route for the synthesis of starch esters

Starch acetates and starch butyrates with degree of substitution (DS) in the range of 0.06–1.54 were prepared by a simple direct solvent-free organocatalytic methodology of starch acylation. The starch esters synthesized have important applications in the food and pharmaceutical industries, among others. The acylation methodology used involves a non-toxic biobased α-hydroxycarboxylic acid as catalyst, and proceeds with high efficiency in absence of solvents. The effect of reaction time on the advance of starch modification was studied as a simple way to control the level of substitution achieved, when all other reaction parameters were kept constant. Starch esters were characterized by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). FTIR spectroscopy qualitatively confirmed the esterification of starch by the appearance of bands which are associated with esters groups. Scanning electron microscopy showed that the granular structure of the polysaccharide was preserved upon acylation, although acylated granules had rougher surfaces; and wrinkles, grooves and deformed zones appeared in some granules at high DS. Thermogravimetric analysis showed a gradual reduction in the water content of acylated starches, as well as noticeable changes in their thermal properties at increasing DS. X-ray diffraction analysis showed that the acetylation treatment led to lower crystallinity at increasing DS, although characteristic corn starch A-type patterns could be identified even at the highest DS achieved (DS = 1.23). Specific bands and weight losses derived from FTIR and TGA data could be very well correlated with the substitution degree achieved in acetylated starches at DS lower/equal than 0.6. The organocatalytic methodology described for the synthesis of starch acetates and butyrates has the potential to be easily extended to the synthesis of other starch esters using a variety of anhydrides or carboxylic acids as acylating agents     

Properties of biodegradable citric acid-modified granular starch/thermoplastic pea starch composites

Pea starch-based composites reinforced with citric acid-modified pea starch (CAPS) and citric acid-modified rice starch (CARS), respectively, were prepared by screw extrusion. The effects of granular CAPS and CARS on the morphology, thermal stability, dynamic mechanical thermal analysis, the relationship between the mechanical properties and water content, as well as the water vapor permeability of the composite films were investigated. Scanning electron microscope and X-ray diffraction reveal that the reinforcing agents, the granules of CAPS and CARS, are not disrupted in the thermoplastic process, while the pea starch in the matrix is turned into a continuous TPS phase. Granular CAPS and CARS can improve the storage modulus, the glass transition temperature, the tensile strength and the water vapor barrier, but decrease thermal stability. CARS/TPS composites exhibit a better storage modulus, tensile strength, elongation at break and water vapor barrier than CAPS/TPS composites because of the smaller size of the CARS granules.     

Transport of methotrexate in L1210 cells: Mechanism for inhibition by p-chloromercuriphenylsulfonate and N-ethylmaleimide

Methotrexate transport in L1210 cells is highly sensitive to inhibition by p-chloromercuriphenylsulfonate (CMPS) and, to a lesser extent, by N-ethylmaleimide. A 50% reduction in the methotrexate influx rate occurred upon exposure of cells to 3 μM CMPS or 175 μM N-ethylmaleimide, while complete inhibition was achieved at higher levels of these agents. Dithiothreitol reversed the inhibition by CMPS, suggesting that a sulfhydryl residue is involved. This residue is apparently not located at the substrate binding site of the transport protein, since methotrexate failed to protect the system from inactivation by either CMPS or N-ethylmaleimide, and the transport protein retained the ability to bind substrate (at 4°C) after exposure to these inhibitors (at 37°C). Methotrexate efflux was also inhibited by CMPS (50% at 4 μM), indicating that both the uptake and efflux of methotrexate in L1210 cells occur via the same transport system. High concentrations of CMPS (greater than 20 μM) increased the efflux rate, apparently by damaging the cell membrane and allowing the passive diffusion of methotrexate out of the cell.