Synthesis,characterisation and in vitro digestibility of carboxymethyl potato starch rapidly prepared with microwave-assistance

Carboxymethyl potato starch was synthesised with the aid of microwave. Optimal degree of substitution (DS) of 0.32 was obtained at 45 °C in 25 min using aqueous ethanol media with water/solvent of 0.15 at 200 W. The molar ratio of sodium hydroxide and monochloroacetic acid to anhydroglucose unit for optimal DS were 2.5 and 1.0, respectively. FT-IR spectrometry revealed the carboxymethyl starch to show new bands at ν = 1614 cm⁻¹ and ν = 1429 cm⁻¹. Wide angle X-ray diffractometry and DSC revealed a remarkable reduction in starch crystallinity after carboxymethylation, which was consistent with destroyed surface observed in SEM. The digestibility of carboxymethyl starch (CMS) was lower than that of native starch. With similar DS, there was no difference in digestibility of carboxymethyl starch prepared with and without microwave. As DS increased from 0.05 to 0.32, the amount of resistant starch in microwave-assisted carboxymethyl starch was elevated from 14.6% to 20.0%, which was much higher than that of native starch (10.8%).     

Starch Derivatives of High Degree of Functionalization. 13. Novel Amphiphilic Starch Products

Amphiphilic starch derivatives of high degree of substitution (DS) were prepared by benzylation of pea, potato and waxy maize starch followed by the introduction of hydroxypropyltrimethylammonium and carboxymethyl moieties. The conversions were carried out under heterogeneous conditions leading to products with a total DS of up to 1.8. The starch composition regarding amylose and amylopectin influences the DS value. The structure of the products was characterized by means of elemental analysis, FTIR and NMR spectroscopy, and, in case of benzyl carboxymethyl starch by means of HPLC after complete chain degradation. The tensioactive properties depend on the DS values of hydrophilic and lipophilic groups and can be adjusted by controlling the molar ratio anhydroglucose unit to reagent during the synthesis. Surface tensions as low as 48.6 mN/m were found for benzyl hydroxypropyltrimethylammonium starch and 38.6 mN/m for benzyl carboxymethyl starch. The lowest critical micelle concentration determined is 2.1 mmol/L.     

Study on the morphology,crystalline structure,and thermal properties of Fritillaria ussuriensis Maxim. starch acetates with different degrees of substitution

Fritillaria ussuriensis Maxim. starch acetates with different degrees of substitution (DSs) were prepared by reacting native starch with glacial acetic acid/acetic anhydride using sulfuric acid as catalyst. XRD of acetylated starch revealed that there was loss of crystallinity with increasing DS. The carbonyl group signal at 1750 cm⁻¹ appeared in the FTIR spectra. The intensity of this peak increased whereas the intensity of the hydroxyl groups at 3000–3600 cm⁻¹ decreased. The thermal behavior of the samples was investigated and the results showed that the acetylation decreased the gelatinization temperatures and ΔH_gel, and thermal stability of high DS acetylated starch (DS = 2.82) was much better than that of the original starch and partially substitute starch acetate (DS = 1.52). The SEM suggested that most of the starch granules were disintegrated into many visible fragments along with the increasing of DS. The starch acetate with different DS prepared in this paper has many potential uses in food and pharmaceutical applications for its lower gelatinization temperature and thermal stability properties.     

Structure Analysis of Carboxymethyl Starch by Capillary Electrophoresis and Enzymic Degradation

Carboxymethyl starches (CMS) with a degree of substitution (DS) in the range of 1.2 to 1.5 were analysed by capillary electrophoresis (CE) after hydrolysis and reductive amination in a borate buffer. The monomer composition determined was compared to data calculated by the statistical models of Spurlin and Reuben. In addi­tion, the starch derivatives were exhaustively degraded by α‐amylase and amylo­glucosidase and the amount of glucose liberated was determined. Results were discussed with regard to derivatisation conditions and properties of the carboxymethyl starches.     

Synthesis of Higher Fatty Acid Starch Esters using Vinyl Laurate and Stearate as Reactants

This paper describes the synthesis of long‐chain fatty esters of corn starch (starch laurate and starch stearate) with a broad range in degree of substitution (DS = 0.24−2.96). The fatty esters were prepared by reacting the starch with vinyl laurate or vinyl stearate in the presence of basic catalysts (Na₂HPO₄, K₂CO₃, and Na acetate) in DMSO at 110°C. The yellowish products were characterized by ¹H‐, ¹³C‐NMR and FT‐IR. The DS of the products is a function of the carbon number of the fatty acid chain, vinyl ester to starch ratio and the type of catalyst. When performing the reactions using Na₂HPO₄ as the catalyst, the DS for the starch laurate compounds is higher than for the corresponding starch stearates. For low vinyl ester to starch ratios, an increase in the vinyl ester concentration leads to higher product DS values. At higher ratios, the DS decreases, presumably due to a reduction of the polarity of the reaction medium. K₂CO₃ and Na acetate are superior catalysts with respect to activity compared to Na₂HPO₄ and products with DS values close to 3 were obtained.     

Molekulargewichtsbestimmungen von Carboxymethylstärken

Molecular Weight Determinations of Carboxymethyl Starches. At the synthesis of carbomethylated starches of different degrees of substitution (DS) by monochloracetic acid on starch in alkali solution reacting in the presence of acetone for different periods of reaction time a partial decomposition of the macromolecules takes place. It could be stated that with increasing the substitution degrees the molecular weight of the ethers decreased relatively the most rapidly in the samples of lower substitution degrees. The mean values M_n of the carboxymethylated ethers were determined by a chemical method of work which has been applied also for the determination of molecular weight of native starches. In order to determine the reducing capacities the factor f in dependence of the degree of substitution of the carboxymethyl starches has been calculated.     

羧甲基化反应对大米淀粉性质影响的研究

以大米淀粉为原料,氯乙酸为醚化剂采用异丙醇溶剂法制备了不同取代度的羧甲基淀粉(DS 0.34~0.72),并对其理化性质如冻融稳定性、透明度、凝沉性、溶解度、膨胀度、糊化特性及其结构进行了研究。红外图谱结果表明,籼米淀粉分子上引入了羧甲基基团。通过扫描电镜(SEM)分析了羧甲基化对淀粉颗粒的形貌影响,其结果表明,羧甲基化对淀粉颗粒的结构造成了破坏,其结构破坏程度与取代度有关。羧甲基淀粉由于引入了羧甲基基团,凝沉性减弱,改性后的淀粉具有较好的冻融稳定性、较高的透明度、膨胀度和溶解度,且都随着取代度的增加而增加。此外,相对于原淀粉,羧甲基大米淀粉糊化温度明显降低,粘度升高。      

Experimental Studies on the Carboxymethylation of Arrowroot Starch in Isopropanol‐Water Media

The reaction between granular arrowroot starch and sodium monochloroacetate (SMCA) in isopropanol‐water mixtures has been studied in a systematic way using experimental design strategies. The effect of six factors, i.e. the theoretical degree of substitution (DS_t), reaction time, weight fraction of water in the mixture, NaOH/SMCA ratio, temperature and weight fraction of starch on three responses, i.e. the degree of substitution (DS), the conversion of SMCA and the selectivity of SMCA towards carboxymethyl starch, has been determined in a systematic manner. Granular carboxymethyl arrowroot starch with a maximum DS of 1.4 could be prepared in a singlestep procedure. The results are compared with data obtained for potato starch. Similar trends for all responses were observed, suggesting close similarities between the chemical composition and the topochemistry of granular arrowroot‐ and potato‐starch.     

淀粉基胃漂浮控释载体的制备及其控释特性

通过在淀粉分子中引入羧甲基基团,制备了淀粉基胃漂浮控释系统载体材料。系统考察了不同羧甲基取代度对淀粉基胃漂浮控释系统载体结构和性能的影响规律。结果显示,随着取代度的提高,羧甲基淀粉的结晶程度降低,溶胀性能先增大后降低,当取代度为0.08时,其溶胀性能比原淀粉提高了10倍。在此基础上,选择维生素B1作为模型功能活性物质,羧甲基淀粉作为胃漂浮控释系统载体材料,制备了胃靶向漂浮控释系统,并考察了其对维生素B1在体外模拟胃液中的释放性能。结果表明,羧甲基淀粉胃漂浮控释系统具有良好的漂浮性能和控缓释性能。以取代度为0.08的羧甲基淀粉为载体,所制得的淀粉基胃漂浮控释系统起漂时间小于2 min,持续漂浮时间可达8 h。体外释放动力学研究显示,此羧甲基淀粉胃漂浮控释系统可使维生素B1释放时间延长至6 h,释放行为符合零级动力学。     

Feinstruktur und Hyperfeinstruktur von klinisch verwendeter Hydroxyethylstärke

Fine Structure and Hyperfine Structure of Clinically Applied Hydroxyethyl Starch. The Mark-Houwink-relationships for different samples of clinically used hydroxyethyl starches were established by multi-detection HPGPC. In combination with the degree of branching, the degrees of substitution DS and the molar substitution MS for the different molecular regions were measured by gas chromatographic methylation analysis. Within the molecular regions of non reducing anhydroglucose units, branching units and linear units we found characteristic differences. For hydroxyethyl starches which were prepared from enzymatically hydrolyzed waxy maize starch by α-Amylase, we found a significantly higher degree of branching than for samples prepared by acid hydrolysis. The clinical relevance of these results is discussed.     

A Study of Native and Chemically Modified Potato Starch. Part I: Analysis and Enzymic Availability in vitro

The availability of native and chemically modified potato starch to α-amylase was studied in vitro (distarch phosphate, acetylated distarch phosphate and hydroxypropyl distarch phosphate). Enzyme availability was also related to results obtained during analysis of starch and dietary fibre, The degree of substitution (DS) was determined by ¹HNMR spectroscopy and the substitution sites were evaluated by gasliquid chromatography and mass spectrometry. Substitution with acetyl- and hydroxypropyl groups reduced the availability of drum-dried starch derivatives to α-amylase. In contrast, the susceptibility of raw starch increased after introduction of hydroxypropyl groups. Cross-linking with phosphate only had but minor effects on enzyme availability. The recovery of starch during analysis depended on (a) degree of hydrolysis to glucose (b) whether or not the substitution groups were removed. The lowest yields were observed when analyzing substituted derivatives after boiling and enzymic hydrolysis (60-70%). Enzymically unavailable starch was not recovered as dietary fibre when using an enzymic gravimetric assay.     

Bestimmung der funktionellen Gruppe und des durchschnittlichen Substitutionsgrades von Carboxymethylstärke

Determination of the Functional Group and the Average Degree of Substitution of Carboxymethyl Starch. To characterize chemically modified starch derivatives, it is necessary to know their proportion of functional groups. In the case of carboxymethyl starch, it is the molar ratio of the  CH₂COONa group to the glucose units of the starch molecule which gives the average degree of substitution. With the present method of analysis, developed for production control, the  CH₂COONa group of the carboxymethyl starch is determined by precipitation of its copper salt and back titration of the excess copper in the filtrate with ethylenediamine tetraacetate using Murexide as the indicator.     

Experimental and Modeling Studies on the Synthesis and Properties of Higher Fatty Esters of Corn Starch

This paper describes a systematic study on the synthesis of higher fatty esters of corn starch (starch laurate and starch stearate) by using the corresponding vinyl esters. The reactions were carried out in DMSO using basic catalysts (Na₂HPO₄, K₂CO₃, and Na‐acetate). The effect of the process variables (vinyl ester to starch ratio, catalyst intake, reaction temperature and type of the catalyst) on the degree of substitution (DS) of the starch laurate and starch stearate esters was determined by performing a total of 54 experiments. The results were adequately modeled using a non‐linear multivariable regression model (R²≥0.96). The basicity of the catalyst and the reaction temperature have the highest impact on the product DS. The thermal and mechanical properties of some representative product samples were determined. High‐DS products (DS = 2.26‐2.39) are totally amorphous whereas the low‐DS ones (DS = 1.45‐1.75) are still partially crystalline. The thermal stability of the esterified products is higher than that of native starch. Mechanical tests show that the products have a tensile strength (stress at break) between 2.7–3.5 MPa, elongation at break of 3–26%, and modulus of elasticity of 46–113 MPa.     

Carboxymethyl Cocoyam Starch: Synthesis,Characterisation and Influence of Reaction Parameters

Twenty carboxymethyl starch derivatives of cocoyam starch were synthesized under different reaction conditions. The influences of sodium hydroxide concentration, sodium monochloroacetate concentration, water, type of organic solvent, reaction time and temperature were evaluated for degree of substitution (DS) and reaction efficiency (RE). The optimal ratio of moles of NaOH per mole anhydroglucose unit (AGU), n_NaOH/n_AGU was 1.62. Increases in ratio of moles of monochloroacetate (n_SMCA) to mole of AGU (n_AGU) increased the DS progressively. The ratio of water to solvent (isopropanol, IPA) in the reaction media was optimal at H₂O/IPA 0.16. Both RE and the DS increased with increase in reaction time within the studied time range (1‐4 h). Increases in temperature enhanced both reaction efficiency and DS. Among the solvents studied, an isopropanol – water medium produced the optimal result. The starch paste clarity improved remarkably after carboxymethylation. Wide angle X‐ray diffractometry revealed that starch crystallinity was reduced after carboxymethylation. ¹³C‐NMR showed peaks at δ = 180.42 ppm, 80.35 ppm, 77.77 ppm, and 71.96 ppm, which were assigned to C‐O, substituted C‐2, C‐3 and C‐6, respectively. In addition, three signals appeared at δ = 74.16 ppm, 73.42 ppm and 72.59 ppm and they were assigned to the CH₂ in the carboxylate substituents.     

Preparation and Properties of Octenyl Succinic Anhydride Modified Early Indica Rice Starch

Octenyl succinic anhydride (OSA) modified early indica rice starch was prepared in aqueous slurry systems and the major factors affecting the esterification were investigated systematically. The physicochemical properties of the products were determined by means of Fourier transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM), X‐ray diffraction and Rapid Visco Analyser (RVA). The results indicated that the suitable parameters for the preparation of OSA starch from early indica rice starch in aqueous slurry systems were as follows: concentration of starch slurry 35% (in proportion to water, w/w), reaction period 4 h, pH of reaction system 8.5, reaction temperature 35°C, amount of OSA 3% (in proportion to starch, w/w). The degree of substitution (DS) was 0 018 and the reaction efficiency (RE) was 78%. FT‐IR spectroscopy showed characteristic absorption of the ester carbonyl groups in the OSA starch at 1724 cm^‐1. SEM and X‐ray diffraction revealed that OSA groups acted by first attacking the surface and some pores formed, but OSA modification caused no change in the crystalline pattern of rice starch up to DS 0.046. RVA results indicated that the starch derivatives gelatinized at shorter time to achieve higher viscosities with increased OSA modification.     

Effect of acetylation on the properties of corn starch

Acetylated corn starches with different degrees of substitution (DS 0.85, DS 1.78, DS 2.89) were synthesized by the reaction of corn starch with acetic anhydride in the presence of acetic acid under varying reaction temperatures. The product was characterized by FTIR spectroscopy, ¹H NMR, X-ray diffraction and contact angle measurement. Acid-base titration and ¹H NMR methods were employed to determine the degree of substitution of product. FTIR spectroscopic analysis showed that the characteristic absorption intensities of esterified starch increased with increase in the degree of substitution, and the characterized peak of hydroxyl group almost disappeared in the spectrum of DS 2.89 acetylated starch. The detailed chemical microstructure of native starch and acetylated starch was confirmed by ¹H NMR, ¹³C NMR and ¹³C–¹H COSY spectra. Analysis of ¹H NMR spectra of acetylated starches was assigned accurately. Strong peaks in X-ray diffraction of acetylated starch revealed that new crystalline regions were formed. Compared with native starch, the hydrophobic performance of acetylated starch esters was increased. The contact angle of acetylated starch with DS 2.89 was 68.2°.     

Starch Derivatives of High Degree of Functionalization. 4. Homogeneous Tritylation of Starch and Subsequent Carboxymethylation

The synthesis of monomethoxytriphenylmethyl (MMtrityl) starch and the subsequent carboxymethylation of the 6‐O‐functionalized products were investigated. The trityIation both in N,N‐dimethylacetamide (DMA)/LiCl and in dimethyl sulfoxide (DMSO) occurred homogeneously. The highest degree of substitution of trityl groups (DS_TrityI) obtained after a single conversion step was 0.77 in both solvents. A complete functionalization of primary OH‐groups was achieved only with unsubstituted triphenylmethyl chloride in these reaction media. In case of monomethoxytriphenylmethyl chloride (MMTMC) as reagent an additional conversion step is necessary to synthesize products with a DS_TrityI = 1. The structure of the products was analyzed by FTIR‐ and ¹³C‐NMR spectroscopy. Subsequent carboxymethylation of the MMtrityl starch samples leads to products with a preferred functionalization of the unprotected secondary OH‐groups. After removal of the trityl moieties, the DS_CM and the distribution of carboxymethyl groups within the anhydroglucose unit was investigated by means of HPLC and ¹H‐NMR spectroscopy. The carboxymethylation was more effective at O‐2 than at O‐3. In case of ether products with DS_Trityl < 1 a partial substitution of the primary OH group took place as well.     

Octenylsuccinate Derivatives of Carboxymethyl Starch – Synthesis and Properties

Carboxymethyl starch (CMS, DS_CM 0.1) was modified with octenylsuccinic anhydride in various solvent systems. Using the dimethyl sulphoxide (DMSO)/p‐toluenesulphonic acid (p‐Ts‐OH) system, carboxymethyl starch octenylsuccinates (OS‐CMS) were obtained with degrees of substitution (DS) ranging from 0.03 to 0.53 at high reaction efficiency, and characterized with regard to their molecular structure, their rheological and surface active properties. The water‐soluble OS‐CMS derivatives showed a pseudoplastic behavior dependent on both the DS and polymer concentration (c_p). The thickening power displayed a maximum at DS 0.14 at higher c_p (2.5 and 5.0%). In spite of the only moderate surface‐tension decreasing effect of the OS‐CMS derivatives, most of them exhibited excellent emulsifying, foaming and antiredeposition effects. They represent novel polysaccharide‐based biosurfactants with a broad application potential.     

Synthesis and Optimization of the Reaction Conditions of Starch Sulfates in Aqueous Solution

Starch sulfate was prepared by chemical modification of potato starch with trisulfonated sodium amine (N(SO₃Na)₃), which was synthesized by reaction of sodium bisulfite and sodium nitrite in aqueous solution. The factors that could affect the degree of substitution (DS) of potato starch were investigated in detail, which included reaction temperature and time of preparing the sulfating agent, reaction temperature and time of synthesizing the starch sulfate, dosage of sulfating agent and potato starch, pH of sulfation reaction medium, and the ratio of liquid volume to starch mass. A starch sulfate with DS of 2.14 was obtained under optimal conditions. FTIR spectra showed the characteristic absorptions of sulfate ester bonds at 1236 cm⁻¹ and 821 cm⁻¹.     

Synthesis and Application of Starch 3, 5‐Dinitrobenzoate

A novel starch ester was prepared by the reaction of starch and 3, 5‐dinitrobenzoyl chloride (DNBZ‐Cl). The product (starch 3, 5‐dinitrobenzoate, DNBZ‐ST) was characterized by means of elemental analysis, Fourier Transform Infrared (FTIR) and ¹³C NMR spectroscopy. The influences of molar ratio of DNBZ‐Cl to anhydroglucose (AGU), reaction temperature and time, and amount of pyridine on the degree of substitution (DS) were studied. The esterification reaction is essentially complete after 2 h. Increase in the molar ratio of DNBZ‐Cl to AGU leads to an increase in DS when the former varies from 2:1 to 5:1. DS increases with the reaction temperature when the latter is varied from 70 to 100 °C. DS first increases and then decreases with amount of pyridine, the highest DS was obtained when V(pyridine)/m(starch) was 53 mL/g. The thermal stability of DNBZ‐ST increases when the DS increases, and the degradation starts at 353 °C for the sample of DS 2.14. Creatinine is a toxin accumulated in the blood of chronic renal failure (CRF) patients and a special adsorbent for creatinine is not reported in literature. DNBZ‐ST displayed specific adsorption ability for creatinine, the adsorption equilibrium is reached after 4 h. The adsorption capacity increases with the DS of adsorbent and creatinine concentration. When the creatinine concentration is higher than 300 mg/L, concentration has no apparent effect on the adsorption capacity. As the temperature of the solution is varied from 19 to 49 °C, adsorption capacity first decreases and then increases, being lowest at 37 °C. The adsorption capacity first increases and then decreases as the pH value increases, and is highest at pH 8.The highest adsorption capacity obtained was 25 mg of creatinine per gram of adsorbent at 37 °C, pH 7 and a creatinine concentration of 100 mg/L. The study on the FTIR and UV‐VIS spectra suggested that some chemical reaction took place between the DNBZ‐ST and creatinine in buffer solution.