Solid State NMR and X‐ray Studies on Amylose Complexes with Small Organic Molecules

Crystalline complexes of amylose with lauric acid, n‐butanol, n‐pentanol, dimethyl sulfoxide and thymol were examined by ¹³C CP/MAS NMR and X‐ray diffraction methods. The complexes displayed the single helix V‐amylose structure and were heat stable at least up to 90 °C. In addition, the X‐ray diffraction pattern of the amylose‐n‐butanol complex was similar to that of the amylose‐n‐pentanol complex which is interpreted to mean that the guest agents are not present in crystallographic register. It is suggested that the guests are in a matrix, of crystal surfaces, dislocations and chain folds, such that only the amylose chains contribute to the observed crystalline diffraction patterns. After humidification, the NMR spectra showed partial transformation to the double helix B‐polymorph for all complexes except that formed with lauric acid. The transformation is dependent on the alkyl chain length of guest agents. Once the double helix polymorph was formed, it was permanent unless the sample was redissolved.     

The Impact of Thermal Events on Amylose‐Fatty Acid Complexes

The molecular behavior of amylose‐lipid complexes was studied using differential scanning calorimetry. rapid viscoanalysis and texture analysis methods. Three amyloses were fractionated, one each from regular, 50% amylose and 70% amylose corn starches. High performance size exclusion chromatography, coupled with multiple angle laser light scattering, was used to determine amylose molecular weight profiles; fractions differed statistically (P>0.05) in their z‐average molecular weights (M_z). Each amylose fraction was complexed with five different fatty acids. After 12 days of storage, amylose‐lipid complexes had recrystallization percentages ranging from 42.7 to 98.2%. Cohesiveness (r = ‐0.84) and adhesiveness (r = ‐0.75) decreased with increasing M_z of amyloses (P>0.05). An inverse relationship was obtained between fatty acid chain length and percent recrystallization (r = ‐0.84, P>0.05). Percent recrystallization decreased when fatty acid chain length increased from C16:0 to C18:0. All complex samples, when adjusted to an equal total starch basis, had decreased viscosities when pasted compared to their native starch or amylose counterparts. Shear thinning of complexes increased with increasing molecular weight (M_z) of amyloses (r = 0.71, P>0.05). Lower recrystallization rates and decreased viscosity properties could be accomplished complexing by amylose and fatty acids.     

Physicochemical properties of thermal alkaline treated pigeonpea (Cajanus cajan L.) flour

Thermal alkaline treatment, normally used for corn, was applied to pigeonpea grains. Starch granules were isolated using wet milling and alkaline treatments. Effects of the calcium hydroxide [Ca(OH)₂] concentration in the range of 0–1% (w/v) on granule structure, crystalline structure, chemical composition, and physicochemical, thermal, and pasting properties of isolated starch granules were determined. Compared to native samples, thermal alkaline treated samples had higher protein, lipid, calcium, and phosphorus contents, but lower starch and amylose contents. Thermal alkaline treatment increased starch granular size and gelatinization temperatures, but decreased relative crystallinity, gelatinization enthalpy, swelling power, solubility, amylose leaching, and the pasting viscosity. Amylose-lipid complexes were not found in thermal alkaline treated flours. As the Ca(OH)₂ concentration increased, the amylose content, relative crystallinity, gelatinization temperature, and enthalpy also increased, but the swelling power, solubility, amylose leaching, and paste viscosity decreased. A higher Ca(OH)₂ concentration produced more stable starch granules that resisted re-gelatinization.     

Crystalline Amylose-Fatty Acid Complexes: Morphology and Crystal Thickness

The influence of amylose (DP 30, 40, 80 and 900) and fatty acid (C8, C12 and C16) chain lengths on morphology and crystal thickness of crystalline amylose-fatty acid complexes was studied by transmission electron microscopy (TEM) and by size exclusion chromatography (SEC) of hydrolysis residues obtained after Bacillus subtilis amylase attack. Lamellar arrangements formed by alternation of crystalline and amorphous areas were observed, with dimensions strongly dependent on amylose DP. Crystal thickness increased essentially with amylose chain length up to DP80, i.e. from 1.6nm for the DP30-C16 complex to 4.5nm for the DP80-C16 complex. Assuming six glucosyl residues per helical turn and a step of 0.8 nm for the Vh-type amylose, the measured sizes corresponded to amylose segments with DPs in the range between 12 and 33. A slight increase of crystal thickness was also observed with increasing fatty acid chain length.     

Effect of Amylose Content on Gelatinization,Retrogradation and Pasting Properties of Flours from Different Cultivars of Thai Rice

Presently, rice cultivars are categorized according to amylose content into three groups: low, medium and high amylose content cultivars. The correlation of amylose content with gelatinization properties, retrogradation, and pasting properties of eleven cultivars of Thai rice were investigated. Rice flour was prepared from milled rice by the wet grinding process. Onset (T_o), peak (T_p) and conclusion (T_c) temperatures of gelatinization, (determined by DSC) were found to be highly positively correlated with amylose levels. This correlation could be used for prediction of amylose content of rice flour. Low amylose starch could also be characterized by low degree of retrogradation (%R). The data obtained from RVA‐viscograms (peak viscosity, breakdown, setback, and pasting temperature) can be used only for characterization of the group of low amylose starches (waxy rice). It was demonstrated that low amylose rice starch provided the highest peak viscosity and breakdown and the lowest setback and pasting temperature among the groups investigated.     

Molecular encapsulation of linoleic and linolenic acids by amylose using hydrothermal and high-pressure treatments

The health benefits of polyunsaturated fatty acids are well known, however their fragility is a drawback as it leads to their degradation. The objective of this study was to develop innovative assemblies, using the capacity of starch to encapsulate small molecules, for the protection of polyunsaturated fatty acids like linoleic acid and linolenic acid. These assemblies were produced by hydrothermal treatment, and by high-pressure treatment (20 min at 500 MPa at a temperature of 40 °C). They were then analyzed and characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), nuclear magnetic resonance (¹³C CP/MAS NMR) and a heating cell in XRD. The results showed that amylose–ligand complexes were formed during both treatments and two crystalline types V_6I and V_6II were obtained. The techniques used show excellent complementarities in the determination of important structural features such as crystalline type, helical conformation and nature of the inclusion.     

直链淀粉与不同风味分子包合物的制备及其结构表征

为研究直链淀粉与风味分子的制备及所得包合物的结构规律,选择(C6～C9)脂肪族醇和α-萘酚5组风味分子与直链淀粉采用热熔法制取包合物。在100℃将直链淀粉糊化后于密闭容器中加入风味分子,恒温后缓慢冷却离心冷冻干燥制得产物,且包合物收率在45%～50%。通过扫描电子显微镜分析(SEM)、X射线衍射法(XRD)、核磁共振(NMR)确认了包合物的形成;差示扫描量热分析(DSC)、热重分析(TGA)测定表明直链淀粉与正庚醇的包合物结构最稳定,此结果在各种表征结果中存在一致性。实验证实了热熔法可制得稳定的直链淀粉风味分子包合物;包合物包埋率随着脂肪醇链长的增加呈降低趋势。     

Complexes of Starch with Dioic Acids

Attempts are presented for the preparation of complexes of starch with a series of dioic acids (oxalic, malonic, succinic, glutaric and adipic). The complexes are isolated and characterized by potentiometric titration, powder X-ray diffraction, characteristics of gelation and differential scanning calorimetry. These complexes contain dioic acids on the level of 1⁻³g per 1g of starch. Oxalic acid forms a surface complex with crosslinking involving both its carboxylic groups. Malonic acid forms surface complex with involvement of only one of its carboxylic groups and all three succinic, glutaric and adipic acids form inclusion complexes.     

茶多酚/直链淀粉复合物的制备及表征

以马铃薯淀粉为原料制备得到直链淀粉,加入一定比例的茶多酚制备茶多酚/直链淀粉复合物。通过单因素实验,研究反应时间、茶多酚添加量和反应温度对茶多酚包埋效果和复合物相对结晶度的影响。通过X-射线衍射图谱分析得到最佳结晶度的复合条件,并对最优复合物进行扫描电子显微镜(SEM)、X-射线衍射(XRD)、红外光谱(IR)的分析和测试。结果表明,最优结晶结构的制备条件为:反应时间为1 h、淀粉/茶多酚配比为10:1、反应温度为50 ℃,在该工艺下,制得的B型复合物的结晶度最高,为61.51%;XRD测试复合物为典型的B型结晶结构;SEM图片显示复合物颗粒破碎,形状不规则;IR光谱中,由于直链淀粉-正辛醇复合物中淀粉和正辛醇发生叠加,其特征吸收峰的峰强度比茶多酚/直链淀粉复合物与B型微晶淀粉特征吸收峰的峰强度大。     

Formation and stability of amylose ligand complexes formed by high pressure treatment

Starch can be gelatinized during high pressure processing in the presence of water, but to a greater or lesser extent. Starch gelatinization is often accompanied by the formation of amylose complexes, in particular when a thermal treatment is used. Four different starches were considered in this study: potato, broad bean (Vicia faba), pea and tapioca. A comparison between high pressure-induced starch gelatinization (HPG) and conventional thermal gelatinization (TG) was made. In the case of broad bean starch, selected complexing molecules were considered for both thermal and high pressure treatments. Cross polarization/magic angle spinning (CP/MAS) ¹³C NMR, X-ray diffraction and thermal analysis were used to monitor physico-chemical changes in the structure and microstructure of starch preparations. Decanoic acid and carvacrol were selected as complexing agents to track the formation of amylose ligand complexes. It was observed that B-type starch (potato) was more resistant to pressure than the A-type starches (tapioca, broad bean and pea) considered in this study. The results showed that amylose ligand complexes were formed during high pressure treatment (20 min at 500 MPa at temperatures of 20 °C and 40 °C). Decanoic acid induced the complexing of amylose in the V_6I type whatever the treatment used. On the other hand, the complexation of carvacrol appeared to depend on the temperature used during the high pressure treatment. It is assumed that carvacrol forms amorphous complexes with amylose during high pressure treatment. The amylose complexes were characterized by ¹³C CP/MAS NMR confirming the results obtained by X-ray analysis.Industrial relevanceDevelopment of innovative assembly of amylose + molecules of interest (i.e. antioxidant) using a mild processing (40 °C) instead of 90 °C. At 90 °C, some molecules are damaged or oxidized.The use of high pressure permits the production of larger amount of compounds than using conventional thermal treatment. The main reason is that there is no need to solubilise the molecule of interest.     

Digestibility of Amylose-Lipid Complexes in-vitro and in-vivo

Amylose from potatoes was complexed with lysolecithin and oleic acid. The degradation of complexed amylose by hog pancreatic α-amylase in-vitro was studied, as well as the in-vivo absorption in the rat. The presence of a bacterial thermostable α-amylase in the gelatinization step increased the result of a starch analysis using glucoamylase. Complexed amylose displayed a substantially reduced susceptibility to α-amylase in-vitro. However, when adding a large excess of enzyme, the complex was completely hydrolyzed after 3 h. Amylose-lysolecithin complex disappeared from the gastrointestinal tract within 120 min. The complexed amylose was hydrolyzed and adsorbed to the same extent as free amylose in-vivo but somewhat slower.     

淀粉-脂质复合物在热加工过程中的结构变化及其对体外消化性影响

为研究压热处理和回生对硬脂酸与脱支的高直链玉米淀粉之间所形成复合物(HA7-SA)的结构和体外酶消化率的影响,通过X射线衍射、激光共聚焦显微-拉曼光谱、差示扫描量热仪等方法比较处理前后HA7-SA的长程-短程分子有序性和复合物的相转变温度,并采用体外消化实验测定HA7-SA的体外酶消化率.结果发现,压热处理显著降低了H...     

Solvent Extraction of Fatty Acids from Amylose Inclusion Complexes

The extractability of palmitic and other common fatty acids from inclusion complexes with potato amylose was studied using a wide range of common lipid solvents. At ambient temperature negligible yields were obtained with light petroleum or diethyl ether, and yields were low with most other solvents except those containing methanol or water. At 100°C, methanol, ethanol and propanol and all alcohol-water mixtures gave good yields. Complexes of amylose with 1-O-palmitoyllysophosphatidylcholine also gave good yields when extracted with propanol-water (3:1) at 100°C. Since more rigorous conditions are required for extraction of lipids from native cereal starch granules, it seems that the barrier to lipid extraction is the structure of the granule rather than the resistance to lipid extraction of any possible inclusion complexes in the granules.     

The effects of acid and oxidative modification on the expansion properties of rice flours with varying levels of amylose

This study evaluates the effects of acid and oxidative modifications on the development of the expansive properties of rice flours with varying levels of amylose. Rice grains of the cultivars Embrapa-7 Taim (high amylose), BRS Firmeza (medium amylose) and Motti (low amylose) were used. The rice flours were modified with lactic acid and oxidised with hydrogen peroxide at concentrations of 4 g H₂O₂/100 g flour and 8 g H₂O₂/100 g flour in 5 h, 21 h and 27 h reactions. The rice flours were evaluated for chemical composition, pasting properties, carbonyl and carboxyl contents and expansion properties. The effects of modification with lactic acid and oxidation with hydrogen peroxide were more intense in the flour with the lowest amylose content. The modification of rice flour with lactic acid promoted a reduction in amylose content and in pasting viscosity; the exception to this finding was the peak viscosity of Motti rice flour. The acid and oxidative modifications not changed the specific volume of biscuits made with Taim (1.33 mL/g) and Firmeza (1.88 mL/g) rice flours, however for the Motti rice flour promoted the development of baking expansion. The specific volume increased of 6.53 mL/g in biscuits with native Motti rice flour to 15.80 mL/g in biscuits made with Motti rice flour oxidised with 8 g/100 g of hydrogen peroxide for 27 h.     

Characterization of Potato Starch and Its Monoglyceride Complexes

Native potato starch granules and those complexed below the gelatinization temperature with 1-(C₈ to C₁₈)-monoglycerides were compared for solubility, swelling power (SP), viscosity, heat stability and water binding capacity (WBC). X-ray diffraction analysis proved that complexes were true clathrates (inclusion) compounds. Clathrate stability was a function of monoglyceride chain length. The presence of clathrates in granules decreased solubility by up to 90% and SP up to 10-times, while WBC dropped from 0.39 to as low as 0.25 g water/g starch. Endotherm characteristics were given for gelatinization, most perfect crystallite, and clathrate fusions. Enthalpies per mole glucose units of 15.4 kcal/mole for native starch and 27.5 for clathrate were obtained irrespective of monoglyceride chain length.     

Expression of granule‐bound starch synthase in developing rice grain

The expression of granule‐bound starch synthase (GBSS) in rice (Oryza sativa) genotype Tainung 67 (200 g kg^?1 grain amylose content) and its two NaN₃‐induced mutants SA419 and SA418 were examined. G/T polymorphism analysis indicated that SA418 (300 g kg^?1 grain amylose content) carried Wx^a allele. The insertion of 23 base pairs sequence was found only in SA419 (80 g kg^?1 grain amylose content), suggesting that it was a waxy mutant. Microsatellite polymorphisms (CT)_n were also detected on the Wx gene encoding GBSS in the tested genotypes. The activities of several key enzymes involving starch biosynthesis in developing grains of field‐grown rice plants were also compared during grain filling period. Significant genotypic differences were only found in the expression of GBSS. The content of amylose in SA418 grain was higher than Tainung 67 and SA419 grains throughout the entire grain filling period, possibly due to its superiority to synthesize amylose through GBSS. The lowest amylose content of SA 419 grain was attributable to its extremely low activity of GBSS in comparison with the two other genotypes. The mutation effects on the expression of GBSS were confirmed by two‐dimensional electrophoresis and mass spectrometry. Copyright © 2007 Society of Chemical Industry     

Effects of fatty acid chain length on properties of potato starch–fatty acid complexes under partially gelatinization

A series of starch–fatty acid samples were prepared using potato starch and four fatty acids differing in their chain length, including lauric (C12), myristic (C14), palmitic (C16), and stearic (C18) acids. The results indicated that the fatty-acid chain length played a significant role in altering the properties of potato starch–fatty acid complexes. The complexing index of potato starch–fatty acid complexes decreased from 0.38 to 0.18 with increasing carbon-chain length. V-type crystalline polymorphs were formed between starch and four fatty acids, with shorter chain fatty acids preserving more crystalline structure. X-ray diffraction studies revealed that the degree of crystallinity exhibited by the starch samples was dependent on the fatty-acid chain length. In the Fourier transformed infrared spectrum of the samples, the new spikes at 2917, 2850, 1018, and 720 cm^?1 were assumed to be related to the presence of fatty long chains. The formation of amylose–fatty acid complex inhibited granule swelling of potato starch, w\ith longer chain fatty acids showing greater inhibition. Scanning electron microscopy microscopic examination indicated that amylose–fatty acid interactions taken place during starch gelatinization retarded the destruction of the granules.     

脂肪酸链长对高直链玉米淀粉—脂质复合物结构及理化性质的影响

目的：探究淀粉—脂质复合物的形成机理。方法：采用12~18个碳链的脂肪酸与脱支/非脱支高直链玉米淀粉复合,利用差示扫描量热仪、X-射线衍射仪、傅里叶红外光谱仪等分析复合物的热特性、结晶结构及有序结构等,探究脂肪酸链长及脱支/非脱支高直链玉米淀粉对淀粉—脂肪酸复合物结构及性质的影响。结果：脱支处理的淀粉与脂肪酸的复合率随碳链的增长而降低,其中月桂酸复合率最高(15.00%);未脱支处理的淀粉与脂肪酸的复合率随碳链的增长先升高后下降,其中软脂酸复合率(13.73%)最高。复合物的热特性、结晶结构、分子有序度等与其复合程度有关,淀粉和脂肪酸复合后,糊化峰值温度升高,热稳定性升高,经复合后,淀粉由B型结晶结构转变为V型。结论：脂肪酸链长及淀粉脱支对淀粉—脂质复合物结构及理化性质具有较大影响。     

Studying different dimensions of amylose–long chain fatty acid complexes: Molecular, nano and micro level characteristics

Recently amylose inclusion complexes, or V-amylose, have drawn much attention as a possible vehicle for the nanoencapsulation of unsaturated fatty acids. This study aimed to study three different structural strata of V-amylose, the molecular attributes using XRD, DSC and ¹³C CP/MAS NMR and the nanostructures using SAXS. Using these methods it was noted that decreased degree of fatty acid unsaturation induces the formation of more organized and well defined structures. Specifically, calculations based on SAXS data show that regardless of the crystallization temperature saturated SA yields the highest values for parameters like average crystalline lamellar thickness (φ = 0.26) and characteristic particle dimension (R_g = 9.6). SEM shows this trend extends even into the microscopic level. Overall, this study shows that in the case of long chain fatty acids, increased fatty acid unsaturation impairs the structure of amylose inclusion complexes.     

Changes in Some Properties of Starch Granules of Maize Having Amylose-extender Gene by Amylase Attack

Properties of residual starch by glucoamylase attack were investigated in starch granules of maize (Zea mays L.) of amylose-extender (ae) type (commercial “High Amylose-7”; HA-7). As increasing extent of hydrolysis, the amylose and amylopectin fractions decreased and low-molecular-weight materials were accumulated. Decrease in absorption intensity and sift to a range of shorter wavelength in γmax. of absorption spectra of iodine-starch complexes were observed. The minified fractions had a peak of about 22 average glucose-units and were nearly linear chains. It was suggested that the minified materials consisted of portion resisted to amylases in starch granules according to hydrolysis curves by glucoamylase. The fractions concerned to crystalline area of ae starch were suggested from X-ray diffraction patterns.