Study on the morphology, crystalline structure and thermal properties of yam starch acetates with different degrees of substitution

This study was carried out to understand and establish the changes in physicochemical properties of starch extracted from Chinese yam (Dioscorea opposita Thunb.) after acetylation. Yam starch acetates with different degrees of substitution (DS) were prepared by the reaction of yam starch with glacial acetic acid/acetic anhydride using sulfuric acid as the catalyst. Their formation was confirmed by the presence of the carbonyl signal around 1750 cm-1 in the Fourier transform infrared (FT-IR) spectra. The thermal behavior of the native starch and starch acetate were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the starch acetates are more thermally stable than the native starch. The starch esters showed 50% weight loss at tem- peratures from 328℃ to 372 ℃ , while the native starch underwent 50% weight loss at 325℃ . The glass transition temperature (Tg) of the starch decreased from 273℃ to 226℃. The X-ray diffraction (XRD) patterns could be classified as typical of the C-type for yam starch. X-ray diffraction also showed the loss of the ordered C-type starch crystalline structure and the degree of crystallinity of starch de- creased from 36.10% to 10.96% with the increasing DS. The scanning electron microscopy (SEM) sug- gested that the most of the starch granules disintegrated with many visible fragments with the in- creasing DS.     

Comparative Study on the Structural and Physicochemical Properties of Flour and Starch from Dioscorea opposita Thunb

The objective of this work was to investigate and compare the structural and physicochemical properties of Dioscorea opposita Thunb. flour(DF), starch(DS) and purified starch(PDS). DS and PDS showed higher total starch and amylose content as compared to DF. Starch granules of DF were oval shape with rough surface while DS and PDS were relatively smooth by SEM. According to XRD measurements, FT-IR spectroscopy and 13 C CP/MAS NMR spectroscopy, all samples displayed C-type crystalline pattern, and PDS displayed the highest relative crystallinity and short-range order structure. However, DF contained the greatest content of the amorphous-phase. DF displayed the absorption peaks at 1730 and 1560 cm~(-1) related to the characteristic groups of lipid and protein using FT-IR spectroscopy. Furthermore, DF exhibited significantly higher pasting temperature while DS displayed the great peak and breakdown viscosity, as well as PDS had the highest setback and final viscosity, presumably due to the chemical composition and structural differences. DF exhibited the highest gelatinization temperature whereas PDS displayed the greatest gelatinization enthalpy. The pasting and gelatinization properties of flour and starch might be related to the relative crystallinity, short-range order structure or the interactions between starch and its associated compounds. The results allow the improvement in the manufacture of Dioscorea opposita Thunb. flour and starch with desirable pasting and gelatinization properties.     

The Effects of the Modified Starches on the Melting Flow and Biodegradation of the Starch/Glycerol Blend

Summary: The purpose of this study was to improve the melting flow of starch/glycerol(GA) blends by modified starches. A variety of modified starches, which was treated by hydrolysis and acid hydrolysis, with and without ultrasonic treatment were used. The MFI (melt flow index) of blends increased from 0.5g/10min to 300g/10min when the addition of acid hydrolysis starch (0.3M CA-starch) was 70wt%. Their crystalline behaviors were analyzed by XRD results. The ultrasonic treatment has been proved to have the effect of hydrolysis without acids and synergistic effect on recrystalline. The SEM micrographs of the blend with the ultrasonic treatment starch gave the cleaving surface with comparison to the other blends. The weight loss of the blends with acid hydrolysis starches reached to 60∼80% after one week biodegradation as the ultrasonic treatment was used.     

Gelatinization properties of native starches and their Näegeli dextrins

Cassava, potato, sweet potato, and Peruvian carrot starches were hydrolyzed with 15% v/v sulfuric acid solution for up to 30 days. Näegeli dextrins obtained from 1, 3, 6, 12, and 30 days were evaluated using differential scanning calorimeter (DSC) and scanning electron microscopy (SEM). Two phases of hydrolysis were found. The first phase was attributed to faster degradation of amorphous areas of granules, whereas the second phase corresponded to slower degradation of crystalline regions. Peruvian carrot starch was the most susceptible to acid, whereas potato and sweet potato starches were the most resistant. From DSC, it was observed a progressive reduction in peak height and a broadening of peaks with increasing hydrolysis time. The peaks shifted to higher temperatures. Onset temperature decreased on first day of hydrolysis for cassava and Peruvian carrot starches, and on third day for potato and sweet potato. Enthalpy decreased during first stage of hydrolysis in cassava and Peruvian carrot starches, and during second phase, it reduced in all starches. SEM showed that the granule surfaces were degraded by erosion on the first day of treatment, followed by degradation of amorphous areas. On third day, potato and sweet potato starches still displayed some granules almost intact, whereas cassava and Peruvian carrot starch granules were totally degraded, confirming their high susceptibility to acid attack. On sixth day of hydrolysis, starch granules had faceted structures, characteristic of crystalline material. The effect that acid hydrolysis had on thermal properties of starches depended on both hydrolysis stage and starch source.     

Crystalline starch based nanoparticles

Starch is an abundant, natural, renewable, and biodegradable polymer produced by many plants as a source of stored energy. Because of the multiscale structure of starch granules consisting of alternating crystalline and amorphous concentric layers, the controlled acid hydrolysis treatment of starch disrupts this organization and releases crystalline platelet-like particles with nanoscale dimensions. This paper intends to provide a comprehensive overview of their preparation, characterization, properties, and applications.     

半夏淀粉的理化特性

研究了不同产地的4种半夏淀粉的理化特性,包括直链淀粉含量、膨胀度、溶解性、持水性、淀粉粒大小和形貌、结晶类型、热特性和糊化特性等。结果表明,这些半夏淀粉中直链淀粉含量为18.60%～23.91%;膨胀度21.53%～23.09%;溶解度11.5%～32.3%;持水性100.3%～119.0%。淀粉粒单粒球形,卵形或圆半球形,直径2～20μm,复粒由2～3个分粒组成,其结晶类型均为C型,结晶度15.0%～37.9%。用差示扫描量热仪测得的转变温度TO、TP和TC分别为71.58～77.75℃、83.03～83.84℃和89.41～90.99℃,热焓为4.316～5.809 J/g。用快速粘度分析仪测定了4种半夏淀粉的糊化特征值:峰值粘度、热糊粘度、冷糊粘度、稀懈值和回复值分别为149.5～226.2、97.7～127.2、141.8～194.3、50.4～99.0和44.2～67.2 RVU。糊化温度77.8～79.9℃,峰值时间8.3～8.7 min。     

Waxy Maize Starch Nanocrystals as Filler in Natural Rubber

Starch nanocrystals obtained from acid hydrolysis of waxy maize starch granules consist in crystalline nanoplatelets about 6–8 nm thick with a length of 20–40 nm and a width of 15–30 nm. New nanocomposite materials, i.e. natural rubber (NR) filled with waxy maize starch nanocrystals were processed by casting. Dynamic mechanical analysis has shown that starch nanocrystals were a good reinforcing agent for NR at temperatures higher than the glass transition temperature of NR. Tensile tests have shown that until a weight fraction of 20 wt%, this new filler presented the advantage to reinforce natural rubber without decreasing significantly the strain at break of the material. These properties may be due to both the morphological nature of starch nanocrystals, and the formation of a percolating starch nanocrystals network within the NR matrix, resulting from hydrogen bonding forces between starch aggregates.     

Study on the morphology, crystalline structure and thermal properties of yellow ginger starch acetates with different degrees of substitution

Yellow ginger starch acetates with different degrees of substitution (DS) were prepared by reacting native starch with glacial acetic acid/acetic anhydride using sulfuric acid as catalyst. X-ray diffraction (XRD) of acetylated starch revealed that the crystal structure of native starch was disappeared and new crystalline regions were formed. Their formation was confirmed by the presence of the carbonyl signal around 1750 cm⁻¹, as well as the reduced hydroxyl groups, in the Fourier transform infrared spectroscopy (FT-IR). The scanning electron microscopy (SEM) suggested most of the starch granules disintegrated with many visible fragments along with the increasing DS. The thermal behavior of the native starch and starch acetate were investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA), it was observed that the thermal stability of acetylated starch depends on the degree of substitution. Thermal stability of high DS acetylated starch is much better than that of the original starch when DS reached to 2.67.     

Structure of starches extracted from near isogenic wheat lines

Differential scanning calorimetry (DSC), acidic hydrolysis and different physico-chemical approaches were used to study thermodynamic and structural characteristics of starches from near-isogenic wheat lines to establish the effect of different combinations of active granule-bound starch synthase isoforms, taking part in amylose biosynthesis, on the structure and thermodynamic properties of starches. Obtained results suggest that the effect of different GBSS I combinations is realized through altered amylose localization within starch granules, reflecting in changes of melting temperature of crystalline lamellae (T _m) and rates of acidic hydrolysis. It has also been demonstrated that changes in T _m values for native wheat starches are determined by amylose content in amylopectin clusters.     

Keto/enol tautomerism in phenylpyruvic acids: structure of the o-nitrophenylpyruvic acid

The synthesis of a tautomeric keto/enol mixture of o-nitrophenylpyruvic acid followed the acid hydrolysis of the azlactone of o-nitrobenzaldehyde was carried out. The structures of the two tautomeric forms were assigned by NMR spectroscopy. X-ray diffraction of a single crystal revealed that the crystalline form corresponds to the keto tautomer. Quantum mechanics calculations in the gas phase confirmed the experimental findings in solution.     

Effects of Variety and Growing Location on Physicochemical Properties of Starch from Sweet Potato Root Tuber

Three sweet potato varieties with purple-, yellow-, and white-fleshed root tubers were planted in four growing locations. Starches were isolated from their root tubers, their physicochemical properties (size, iodine absorption, amylose content, crystalline structure, ordered degree, lamellar thickness, swelling power, water solubility, and pasting, thermal and digestion properties) were determined to investigate the effects of variety and growing location on starch properties in sweet potato. The results showed that granule size (D[4,3]) ranged from 12.1 to 18.2 μm, the iodine absorption parameters varied from 0.260 to 0.361 for OD620, from 0.243 to 0.326 for OD680 and from 1.128 to 1.252 for OD620/550, and amylose content varied from 16.4% to 21.2% among starches from three varieties and four growing locations. Starches exhibited C-type X-ray diffraction patterns, and had ordered degrees from 0.634 to 0.726 and lamellar thicknesses from 9.72 to 10.21 nm. Starches had significantly different swelling powers, water solubilities, pasting viscosities, and thermal properties. Native starches had rapidly digestible starch (RDS) from 2.2% to 10.9% and resistant starch (RS) from 58.2% to 89.1%, and gelatinized starches had RDS from 70.5% to 81.4% and RS from 10.8% to 23.3%. Two-way ANOVA analysis showed that starch physicochemical properties were affected significantly by variety, growing location, and their interaction in sweet potato.     

Preparation of poly (styrene‐co‐allyl sulfonic acid) as a novel catalyst for the alcoholysis of dioscin

This work describes the preparation of a novel solid acid, poly (styrene‐co‐allyl sulfonic acid) (St‐SAA), and its activity test for extracting diosgenin from Dioscorea Zingiberensis C.H. Wright (DZW). The solid acid was synthesized by the radical polymerization of styrene and sodium allyl sulfonate in water/ethanol solution, followed by the acidification. The prepared solid acid was characterized by infrared spectrum (FTIR), thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), element analysis, and scanning electron microscope. The solid acid catalyst was used to extract diosgenin from DZW. It was found that the alcoholysis activity of the solid acid was higher than the hydrolysis activity of sulfuric acid with the same mass under the same conditions. Besides, the solid acid can be separated from the reaction mixture for the recycling extraction of diosgenin, and the solid acid has no loss of mass and no decrease of alcoholysis activity after repeated cycles.     

The effect of pretreatments on surfactin production from potato process effluent by Bacillus subtilis

Pretreatments of low-solids potato process effluent were tested for their potential to increase surfactin yield. Pretreatments included heat, removal of starch particulates, and acid hydrolysis. Elimination of contaminating vegetative cells was necessary for surfactin production. After autoclaving, 0.40 g/L of surfactin was produced from the effluent in 72 h, vs 0.24 g/L in the purified potato starch control. However, surfactin yields per carbon consumed were 76% lower from process effluent. Removal of starch particulates had little effect on the culture. Acid hydrolysis decreased growth and surfactant production, except 0.5 wt% acid, which increased the yield by 25% over untreated effluent.     

Enhancement of palmarumycin C12 and C13 production in liquid culture of the endophytic fungus Berkleasmium sp. Dzf12 by oligosaccharides from its host plant Dioscorea zingiberensis

Three crude oligosaccharides were respectively prepared by acid hydrolysis of three polysaccharides, which were water-extracted polysaccharide (WEP), sodium hydroxide-extracted polysaccharide (SEP) and acid-extracted polysaccharide (AEP) from the rhizomes of Dioscorea zingiberensis. Among the three oligosaccharides, the crude oligosaccharide prepared by acid hydrolysis of WEP was found to be the most efficient elicitor to enhance the production of palmarumycins C(12) and C(13) in liquid culture of endophytic fungus Berkleasmium sp. Dzf12. When OW was applied to the medium at 300 mg/L on day 3 of culture, the maximal yields of palmarumycin C(12) (87.96 mg/L) and palmarumycin C(13) (422.28 mg/L) were achieved on day 15 of culture, which were 9.83 and 3.24-fold in comparison with those (8.95 and 130.43 mg/L) of control, respectively. The results indicate that addition of the oligosaccharides from the host plant D. zingiberensis should be an effective strategy for enhancing production of palmarumycins C(12) and C(13) in liquid culture of endophytic fungus Berkleasmium sp. Dzf12.     

Studies of the separation and characterisation of mixtures of starch and cellulose derivatives by use of chromatography and mass spectrometry

In this work a method was developed for characterisation of commercially available polymers consisting of mixtures of substituted cellulose and starch. Selective hydrolysis with specific enzymes was used to achieve separation of the two polymers in the mixture. Enzymes hydrolysing (1→4)-α-D and (1→6)-α-D-glycosidic bonds were used for the starch part and enzymes hydrolysing (1→4)-β-D-glycosidic bonds for the cellulose part. The hydrolysed fraction was separated from the unhydrolysed fraction and characterised by use of size-exclusion chromatography (SEC), to confirm that enzyme hydrolysis of the different polymers had occurred. High-performance anion-exchange chromatography (HPAEC) was performed to determine the amount of unmodified glucose units (UGU) in the fractions. Electrospray ionisation mass spectrometry (ESIMS) was used for determination of the substituents. All products were converted to monomers by acid hydrolysis to simplify mass spectral identification of the substituents. The monomers were further subjected to acetylation with acetic acid anhydride to facilitate identification of the substituents. By combining the results from the different analytical techniques a picture of the samples was obtained.     

微粉（和微晶）纤维素的微细结构

探讨了微粉化过程对各种纤维素材料超分子结构的影响，结果表明，稀盐酸水解制得的微粉（和微晶）纤维素，在结晶状态（如聚合度，结晶度，晶粒尺寸等）及晶粒聚集体的形态结构上，均随纤维素晶型的不同而变，并与硫酸水解和机微粉化不同，Ｘ－射线衍射分析显示，微粉化产物仍保持其纤维素材料原来的晶型和两相（晶区与非晶区）共存的微细结构。     

Impacts of Hydrothermal Treatments on the Morphology,Structural Characteristics,and In Vitro Digestibility of Water Caltrop Starch

The influence of hydrothermal treatments on the structural properties and digestibility of water caltrop starch was investigated. Scanning electron microscopy (SEM) showed some small dents on the surface of starch granules for samples treated with heat moisture treatment (HMT), but not for samples treated with annealing (ANN) which generally showed smoother surfaces. The gelatinization temperature of starch was generally increased by hydrothermal treatments, accompanied by a trend of decreasing breakdown viscosity. These results implied the improvement of thermal and shearing stability, particularly for HMT in comparison to ANN. After being cooked, the native and ANN-modified water caltrop starch granules were essentially burst or destroyed. On the other hand, the margin of starch granules modified by HMT and dual hydrothermal treatments remained clear with some channels inside the starch granules. X-ray diffraction revealed that the crystalline pattern of water caltrop starch changed from the C_A-type to the A-type and the relative crystallinity reduced with increasing moisture levels of HMT. Results of ANN-modified water caltrop starch were mostly similar to those of the native one. Moreover, water caltrop starch modified with HMT20 and dual modification contained a pronouncedly higher resistant starch content. These results suggested that HMT, ANN, and dual modification effectively modified the functional properties of water caltrop starch.     

A new steroidal saponin from Dioscorea zingiberensis Wright

Two compounds were obtained from the rhizome of Dioscorea zingiberensis Wright. One of them was elucidated as dioscin, the other one was a new compound and characterized as Spirost-5-en-3-yl beta-D-glucopyranosyl (1 --> 3)-beta-D-glucopyranosyl (1 --> 4)-[alpha-L-rhamnopyranosyl (1 --> 2)]-beta-D-glucopyranoside, structure was determined on the basis 2D NMR spectroscopic technique and the result of acid hydrolysis.     

机械活化木薯淀粉氧化产物的结构表征

采用搅拌球磨机对木薯淀粉进行机械活化,以活化60min的木薯淀粉为原料,CuSO4为催化剂,H2O2为氧化剂干法制备氧化淀粉。利用红外光谱、扫描电子显微镜、X-射线衍射等手段对产物的结构进行表征分析,并与原淀粉的氧化产物进行比较。结果表明,机械活化对木薯淀粉的氧化反应有显著的影响。原木薯淀粉的氧化反应主要发生在淀粉颗粒的表面及无定形区,部分发生在结晶区,产物是无定形及结晶状态的结构;活化淀粉的氧化反应在淀粉团粒表面及内部均匀进行,产物是无定形的聚集状态结构。并就机械活化对淀粉氧化的强化机理进行了探讨。     

草酸淀粉酯制备及其性能研究

本文以草酸和玉米淀粉为原料,通过改变原料的摩尔比反应制备了不同取代度(0.1到0.9)的草酸淀粉酯,采用滴定法测定产物的取代度,利用红外光谱和核磁共振表征产物(取代度为0.41)的化学结构,产物中含有羰基的结果表明成功制备了草酸淀粉酯.详细考察了草酸淀粉酯的物理化学性质,利用粘度测定、热重分析、广角X衍射(WXRD)以及湿度吸收等研究不同取代度的草酸淀粉酯的分子量、热稳定性,结晶形态以及吸水性能.结果说明,与玉米淀粉相比,草酸淀粉酯的吸水率随着取代度的提高而增加,其分子量、热稳定性以及结晶性能则呈下降趋势.