Single and multi-step carboxymethylation of water yam (Dioscorea alata) starch: synthesis and characterization

Water yam (Dioscorea alata) starch was carboxymethylated by single and multi-step processes for nine times successively. Optimal degree of substitution (DS) of 0.98 and reaction efficiency (RE) of 70.5% were obtained in the single-step carboxymethylation at 40 degrees C, 3 h in isopropanol-water reaction mixture ratio 1:0.16. The ratio of sodium hydroxide and sodium monochloroacetate moles to anhydroglucose unit moles for the optimal DS and RE were 1.62 and 1.39, respectively. The DS increased progressively as the steps of carboxymethylation increased from 2 to 9 and an optimal DS of 2.24 was obtained. Initial increases in carboxymethylation step increased the RE progressively up to 82.1% after the seventh carboxymethylation step but declined with further increases in the carboxymethylation step. The wide angle X-ray diffractometry and the DSC revealed remarkable changes after carboxymethylation because starch crystallinity reduced significantly. Thermogram of native starch showed a characteristic three-step decomposition with 13.16%, 61.54% and 24.79% weight losses progressively while carboxymethyl derivative showed four decomposition stages with 9.86%, 36.57%, 3.04% and 23.07% weight losses progressively. Studies revealed that carboxymethylation improved thermal stability of the native starch. IR spectrometry revealed that carboxymethyl starch showed new bands at nu=1600, 1426 and 1324 cm(-1). The broad band (13)C NMR spectra of the ultrasonically degraded carboxymethyl starch showed a peak at delta=180 ppm which was assigned to carbonyl carbon.     

Preparation and Application of Carboxymethyl Yam (Dioscorea esculenta) Starch

Yam (Dioscorea esculenta) starch was modified by carboxymethylation. The effect of reaction parameters, amount of sodium hydroxide (NaOH), amount of sodium monochloroacetate (SMCA), and reaction time on the degree of substitution (DS) of carboxymethyl yam starch (CMS), was studied using the Box–Behnken experimental design. Physicochemical and potency to be a tablet disintegrant of CMS were evaluated. CMS with DS in the range of 0.08–0.19 were obtained. The results from regression analysis indicated that the most important factor in controlling DS was the amount of NaOH followed by SMCA content and reaction time. However, high concentration of NaOH and SMCA lowered the DS. The optimal conditions to achieve the highest DS (0.19) were found to be at molar ratios of NaOH and SMCA to anhydroglucose unit of 1.80 and 2.35, respectively, and with the reaction time of 4.8 h. The swelling power and viscosity of CMS increased with an increase in the degree of modification. CMS showed satisfying tablet disintegrant properties. The tablets containing 1.0–4.0 % CMS disintegrated faster than 5 min. Hence carboxymethyl yam starch can be used as an excellent tablet disintegrant in low concentration.     

Effect of carboxymethylation conditions on the water-binding capacity of chitosan-based superabsorbents

A superabsorbent polymer (SAP) from chitosan was provided via carboxymethylation of chitosan, followed by cross-linking with glutaraldehyde and freeze-drying. This work was focused on an investigation of the effects of monochloroacetic acid (MCAA), sodium hydroxide, and reaction time on preparation of carboxymethyl chitosan (CMCS). The CMCS products were characterized using FTIR spectroscopy, and their degrees of substitution (DS) were measured using conductimetry and FTIR analysis. The highest DS value was obtained when the carboxymethylation reaction was carried out using 1.75 g MCAA and 1.75 g NaOH per g of chitosan in 4 h. The water solubilities of the CMCS products at various pHs were also evaluated, and the results indicated a significant impact of the reaction parameters on the solubility of CMCS. The CMCSs with the highest DS value resulted in SAPs having the highest water-binding capacity (WBC). The WBC of the best SAP measured after 10 min exposure in distilled water, 0.9% NaCl solution, synthetic urine, and artificial blood was 104, 33, 30, and 57 g/g, respectively. The WBC of this SAP at pH 2-9 passed a maximum at pH 6.     

Carboxymethyl Chinese yam starch: synthesis, characterization, and influence of reaction parameters

Carboxymethyl starch (CMS) was obtained as a product of the reaction of starch and monochloroacetic acid (MCA) in the presence of sodium hydroxide. The influence of the molar ratio of NaOH/AGU, the molar ratio of MCA/AGU, the reaction time, reaction temperature, and the water content on the degree of substitution (DS) was studied. The optimal molar ratio of NaOH/AGU and MCA/AGU is 2.4 and 1.0, respectively. Increase of the ratio of NaOH/AGU or MCA/AGU leads to an increase in DS, but only to certain extent. The highest values of the DS were obtained when the carboxymethylation was performed at 60 °C for 2.5 h. The water content in the reaction media ethanol was optimal at 20% (v/v). The scanning electron micrographs (SEMs) revealed that the carboxymethylation affected the structural arrangement of the starch and caused granular disintegration. The particle size distribution (PSD) also displayed that the average particle diameter increased greatly after modification from 37.37 μm to 72.88 μm. Wide angle X-ray diffractometry (XRD) revealed that starch crystallinity was obviously reduced after carboxymethylation. The new bands at 1600 cm⁻¹ and 1426 cm⁻¹ in FT-IR indicated that the starch granules were substituted.     

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.     

Microwave assisted alkali-catalyzed transesterification of Pongamia pinnata seed oil for biodiesel production

In this study, microwave assisted transesterification of Pongamia pinnata seed oil was carried out for the production of biodiesel. The experiments were carried out using methanol and two alkali catalysts i.e., sodium hydroxide (NaOH) and potassium hydroxide (KOH). The experiments were carried out at 6:1 alcohol/oil molar ratio and 60 °C reaction temperature. The effect of catalyst concentration and reaction time on the yield and quality of biodiesel was studied. The result of the study suggested that 0.5% sodium hydroxide and 1.0% potassium hydroxide catalyst concentration were optimum for biodiesel production from P. pinnata oil under microwave heating. There was a significant reduction in reaction time for microwave induced transesterification as compared to conventional heating.     

Pine wood carboxymethylation under microwave radiation

The use of microwave radiation was proposed for the intensification of the pine wood carboxymethylation process performed without prior separation into individual components. To obtain the carboxymethylated pine wood in the form of potassium salt, the pine wood was treated with potassium hydroxide and monochloroacetic acid in 2-propanol media. The composition and properties of the resulting products were studied. Carboxymethylated cellulose was extracted from the carboxymethylated pine wood. It was found that the increase of the microwave radiation power (from 210 to 700 W) and of the duration of the first and second carboxymethylation stages (20–30 sec) increases the content of carboxymethyl groups (18.3–25.6%). The solubility of the potassium salts of the carboxymethylated pine wood (10–18%) was abnormally low as compared with that of the sodium salts at similar content of carboxymethyl groups. The viscosity of the aqueous solutions of the carboxymethylated pine wood and the carboxymethyl cellulose extracted from it was studied. It is shown that the samples obtained using the microwave radiation power of 210 W are characterized by abnormal flow curves.     

一步法制备羧甲基茯苓多糖的工艺研究

本实验对在有机溶剂中一步法半合成羧甲基茯苓多糖的合成条件进行了研究。结果表明,乙醇是作为羧甲基化反应的合适介质。反应温度提高能加快反应速度;反应时间延长能提高取代度。茯苓多糖葡萄糖当量与氢氧化钠和一氯乙酸的摩尔比调配适当,能减少副产物羟乙酸钠的产生。     

Microspheres of chitosan/carboxymethyl cashew gum (CH/CMCG): Effect of chitosan molar mass and CMCG degree of substitution on the swelling and BSA release

Chitosan/carboxymethyl cashew gum microspheres (CH/CMCG) were prepared with carboxymethyl cashew gum with two different degrees of substitution (DS) and loaded with bovine serum albumin (BSA). In water, for microspheres formed using low molar mass chitosan (LCH) sample swelling was observed for both CMCG samples and CMCG sample with higher DS showed greater swelling. Using high molar mass chitosan (HCH) sample swelling was observed only for microsphere with high DS of CMCG (DS = 0.44). At pH 7.4, the HCH sample led to a lower degree of swelling. The diffusion coefficients D_v were higher for the higher DS of CMCG in both media and the HCH sample had a lower D_v than LCH one. Faster BSA release rates were observed for beads prepared with the higher DS, whereas those prepared with DS = 0.16 took twice the time to reach similar release profiles. All microsphere systems investigated had a non-Fickian BSA release mechanism.     

A heteropolysaccharide from aqueous extract of an edible mushroom, Pleurotus ostreatus cultivar: structural and biological studies

A water soluble polysaccharide isolated from the hot aqueous extract of Pleurotusostreatus cultivar was found to contain d-glucose and d-galactose in a molar ratio of nearly 7:1. Structural investigation was carried out using acid hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and NMR studies (¹H, ¹³C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above mentioned experiments the structure of the repeating unit of the polysaccharide was established as:This heteroglycan stimulates macrophages, splenocytes, and thymocytes.     

HPLC–MS analysis of iodotyrosines produced by sample hydrolysis: A simple method for monitoring iodinated casein in feed premixes

A new and simple HPLC–MS method was developed for monitoring iodinated casein in feed premixes. In this method, feed premixes were hydrolyzed, and the iodotyrosines thus released were analyzed. Sample pretreatment included precipitation of transition metals ions with Na₂S, hydrolysis with sodium hydroxide, and cleaning up with an Oasis SAX cartridge. Gradient elution was carried out on a C₁₈ column with water (containing 0.1% formic acid) and acetonitrile. Ion detection was performed using ESI positive SIM at m/z 262, 308, 388, and 434. Iodinated casein levels were monitored by qualitative analysis of the iodotyrosines released upon sample hydrolysis and by quantifying the 3,5-diiodotyrosine released. The validation data demonstrated that the method was selective and sensitive (≤0.2 mg g^?1) for iodinated casein and had acceptable accuracy (recoveries: 81.3–106.7%) and precision (RSD: 1.7–16.0%).     

Synthesis and anticoagulant activity of the quaternary ammonium chitosan sulfates

Quaternary ammonium chitosan sulfates with diverse degrees of substitution (DS) ascribed to sulfate groups between 0.52 and 1.55 were synthesized by reacting quaternary ammonium chitosan with an uncommon sulfating agent (N(SO₃Na)₃) that was prepared from sodium bisulfite (NaHSO₃) through reaction with sodium nitrite (NaNO₂) in the aqueous system homogeneous. The structures of the derivatives were characterized by FTIR, ¹H NMR and ¹³C NMR. The factors affecting DS of quaternary ammonium chitosan sulfates which included the molar ratio of NaNO₂ to quaternary ammonium chitosan, sulfated temperature, sulfated time and pH of sulfated reaction solution were investigated in detail. Its anticoagulation activity in vitro was determined by an activated partial thromboplastin time (APTT) assay, a thrombin time (TT) assay and a prothrombin time (PT) assay. Results of anticoagulation assays showed quaternary ammonium chitosan sulfates significantly prolonged APTT and TT, but not PT, and demonstrated that the introduction of sulfate groups into the quaternary ammonium chitosan structure improved its anticoagulant activity obviously. The study showed its anticoagulant properties strongly depended on its DS, concentration and molecular weight.     

N-(carboxymethylidene)chitosans and N-(carboxymethyl)chitosans: Novel chelating polyampholytes obtained from chitosan glyoxylate

Glyoxylic acid, added to aqueous suspensions of chitosan, causes immediate dissolution of chitosan and gel formation within 3–4 h if the pH is 4.5–5.5. Solutions at lower pH values gel after 2 min of warming at 60–80°. Chitosan glyoxylate solutions brought to alkaline pH with sodium hydroxide do not precipitate chitosan. Evidence is given that a Schiff base, namely N-(carboxymethylidene)chitosan, is formed. N-(Carboxymethylidene)chitosans are reduced by sodium cyanoborohydride at room temperature to give N-(carboxymethyl)chitosans, obtained as white, free-flowing powders, soluble in water at all pH values. A series of N-(carboxymethyl)chitosans having various degrees of acetylation and N-carboxymethylation was obtained, and characterized by viscometry, elemental analysis, and i.r. spectrometry. For the fully substituted N-(carboxymethyl)chitosans, the pK′ is 2.3, the pK″ is 6.6, and the isoelectric point is 4.1. The addition of N-(carboxymethyl)chitosan to solutions (0.2–0.5mm) of transition-metal ions produces immediate insolubilization of N-(carboxymethyl)chitosan-metal ion chelates.     

Synthesis and characterization of carboxymethylated cyclosophoraose, and its inclusion complexation behavior

Carboxymethylated cyclosophoraoses (CM-Cys) were synthesized by chemical modification of a family of neutral cyclosophoraoses isolated from Rhizobium leguminosarum biovar trifolii. Structural analyses of the CM-Cys were carried out using NMR and FTIR spectroscopies, and the molecular weight distributions were confirmed with MALDI-TOF mass spectrometry. Based on structural characterization, native cyclosophoraoses were successfully substituted with carboxymethyl groups at the OH-4 and OH-6 of the glucose residues with degrees of substitution (DS) ranging from 0.012 to 0.290. CM-Cys was also used as a host for the inclusion complexation with hydrobenzoin (HB) and N-acetyltryptophan (N-AcTrp) as guest molecules. NMR spectroscopic analyses of the complexes showed that the CM-Cys induced chemical shifts of some protons of the guest molecules upon the complexation. Phase solubility studies of the guest molecules by CM-Cys were performed using HPLC, and the results were compared with those of native cyclosophoraoses. The solubility of HB and N-AcTrp was enhanced by the CM-Cys about 5.1- and 299-fold, respectively.     

Formulation of Bacillus amyloliquefaciens B190 for Control of Lily Grey Mould (Botrytis elliptica)

Calcium hydroxide (0.1%) significantly increased the growth of Bacillus amyloliquefaciens B190, inhibited completely the germination of Botrytis elliptica, and decreased the disease severity caused by B. elliptica on lily. Spraying B. amyloliquefaciens B190 mixed with either 0.025% calcium hydroxide, 0.05% sodium carbonate or 0.025% ammonium nitrate decreased the grey mould disease on lily leaves. B. amyloliquefaciens B190 mixed with 0.025% calcium hydroxide and 0.05% sodium carbonate, or mixed with 0.025% calcium hydroxide and 0.025% ammonium nitrate controlled lily grey mould completely. When the concentration of tested adjuvants was below 0.1% (v/v), adhesive adjuvant, i.e. carboxymethyl cellulose and spreader, i.e. Tween 80 were equally effective to assist B. amyloliquefaciens B190 to control lily grey mould. Calcium hydroxide (0.025%) and 0.05% sodium carbonate mixed with 0.1% Tween 80 significantly controlled lily grey mould. B. amyloliquefaciens B190 mixed with 0.025% calcium hydroxide and 0.05% sodium carbonate, and these two chemicals plus or without 0.1% Tween 80 and 0.05% mineral oil (i.e. emulsion and wettable powder, respectively) was consistently able to control grey mould on lily as well as 100 p.p.m. flusilazole in greenhouse and field trials, respectively.     

Physico-chemical characterization of a new heteropolysaccharide produced by a native isolate of heterofermentative <Emphasis Type="Italic">Lactobacillus</Emphasis> sp. CFR-2182

A heterofermentative Lactobacillus sp. CFR-2182 was isolated from dahi samples and it was found to produce 8.0 and 20.5 g/L heteropolysaccharide (HePS) in EPS medium (a simplified synthetic medium) and modified MRS broth, respectively, after 72 h at 30°C. The total carbohydrate, reducing sugar and moisture contents of the purified HePS were 74, 10.6 and 2 g, respectively, per 100 g on dry weight basis. The HePS produced in EPS medium had glucose and mannose in 17:1 ratio. The HePS was non-gelling and non-film forming type. It was completely soluble in water and 1 N sodium hydroxide solution. Gel permeation chromatography and HPLC analysis indicated considerable heterogeneity of the HePS, having three fractions with molecular weights ranging from 3.3 × 10⁴ to 1.32 × 10⁶ Da. The enzymatic hydrolysis of the HePS with pullulanase and α-amylase [with α(1→4) linkage] indicated the presence of α(1→6) and traces of α(1→4) linkages, respectively. NMR analysis of the EPS revealed unique chemical shifts.     

Date stones of Phoenix dactylifera and jujube shells of Ziziphus lotus as potential biosorbents for anionic dye removal

This study investigated the biosorption of Congo Red (CR) from aqueous solution by Date stones (DS) of Phoenix dactylifera and jujube shells (JS) of Ziziphus lotus. Batch operations were carried out in the liquid phase to observe the effect of various experimental parameters such as contact time, pH, temperature, and initial dye concentration on removal of CR. The characteristics of the DS and JS were also examined by Fourier transform infrared analysis. The biosorption data of CR on DS and JS samples were well fitted with the Langmuir isotherm and pseudo-second kinetics model with a maximum biosorption amount of 45.08 mg g^?1 for DS and 59.55 mg g^?1 for JS at pH = 4, temperature of 50°C, and an initial concentration of 100–800 mg L^?1 after 90 minutes of contact time. The outcomes indicated that DS and JS can be used as a good low-cost alternative for the treatment of effluents containing CR in water.     

Some chemical properties of carboxymethyl derivatives of amino acids

Tritium-labeled carboxymethyl derivatives of various functional groups in proteins show ready exchange of the tritium label when exposed to standard protein hydrolysis conditions (6 n HCl, 21 h, 110 °C). While N_?-[³H]carboxymethyl lysine does not show any tritium exchange, the two N-[³H]carboxymethyl histidine derivatives lose their tritium with a half time of about 15 h, and S-[³H]carboxymethyl cysteine loses its tritium with a half time of about 1.5 h. The tritium exchange of S-[³H]carboxymethyl methionine was so fast that the derivative could not be prepared with any of the tritium label intact. The rate of exchange for this compound was consequently determined by following the disappearance of the methylene NMR signal when S-carboxymethyl methionine was dissolved in D₂O. The half time for the exchange was about 12 min. Mechanisms involving either a sulfonium ion or enolization of the protonated conjugate carboxylic acid appear to give a satisfactory explanation of the relative stability of the different derivatives. The practical use of the differential rate of hydrogen exchange as a means of establishing rapidly and with small quantities of material the site of carboxymethylation in unknown proteins is suggested.     

Comparative multifunctional properties of partially carboxymethylated cotton gauze treated by the exhaustion or pad-dry-cure methods

A commercial cotton gauze was modified by partial carboxymethylation using both exhaustion and pad-dry-cure methods, and varying the reaction time and concentration of monochloroacetic acid and sodium hydroxide to obtain the relative degree of carboxymethylation differently. For each experiment, relative value of the degree of substitution (DS_rel) of the modified cotton was evaluated and compared with whole blood clotting time, absorption and retention of chitosan and silver nitrate solutions, antibacterial activity, and physical properties of whiteness, bursting strength and water absorption. Carboxymethylated cotton gauze with a higher DS_rel value showed a better absorption of chitosan and silver nitrate solutions and retained these two solutions for a much longer time than those of unmodified cotton gauze or carboxymethylated cotton gauze at a lower DS_rel. Carboxymethylated cotton gauzes obtained from exhaustion method showed significant antibacterial activity and higher bursting strength and less affected whiteness index than those treated by pad-dry-cure method.     

Production of omega-3 polyunsaturated fatty acids through hydrolysis of fish oil by Candida rugosa lipase immobilized and stabilized on different supports

This paper describes the fish oil hydrolysis performed to obtain Omega-3 fatty acids using Candida rugosa lipase (CRL) immobilized and stabilized on different supports. The enzyme was successfully immobilized, presenting higher thermal stability than the free enzyme. Besides, the cationic derivatives were more stable than the others derivatives and free enzyme in methanol, propanol and cyclohexane. Reactions of fish oil hydrolysis were carried out in organic aqueous medium using 10?U of biocatalyst per gram of oil, at 37?°C. After 96?h, the CRL immobilized on cyanogen bromide agarose rendered the lower fish oil hydrolysis, producing 218?μM of Omega-3, which was 1.1-fold more than the hydrolysis catalyzed by free enzyme, while the ionic derivatives rendered the highest fish oil hydrolysis producing 582 and 577?μM of Omega-3 using the carboxymethyl and sulfopropyl derivatives, respectively. The carboxymethyl and the sulfopropyl derivatives resulted in a 2.9-fold increase in the hydrolysis of fish oil, making these derivatives attractive for industrial applications.