Effect of phosphorylation of the maize starch on thermal generation of stable and short‐living radicals

Effect of hydrolysis, phosphorylation and treatment with high hydrostatic pressure on thermal generation of stable and short‐living radicals in maize starch was studied by X‐ray diffraction (XRD), electron paramagnetic resonance (EPR) spectroscopy, differential scanning calorimetry and polarized light microscopy. Phosphorus was introduced into maize starch as mono‐ and distarch phosphates. XRD indicated localization of phosphate groups in amorphous part of the granule whereas calorimetric data suggested some cross‐linking of the distarch phosphates. Stable and short‐living radicals with unpaired electron localized at carbon atom were generated in all investigated samples in the temperature range commonly used for processing food. The number of detected short‐living radicals, stabilized by a spin trap, is of two orders of magnitude greater than that of the stable radical species. Hydrolysis and phosphorylation strongly increase the number of stable radicals while pretreatment of the starch with high hydrostatic pressure diminishes their amount. The EPR spectra of stable radicals consist of two components, single line and another one with hyperfine structure, indicating interaction of unpaired electron with neighboring hydrogen atom. The EPR spectra of the spin trap adducts with short‐living radicals contain three components from species differing in their dynamic properties depending on localization in zones of various degree of crystallinity.     

Studies on Starch Phosphate. Part 2. Isolation of Glucose 3-Phosphate and Maltose Phosphate by Acid Hydrolysis of Potato Starch

Three sugar phosphates, 4-0-(α-D-6-phosphoglucosyl)-D-glucose, glucose 3-phosphate, and glucose 6-phosphate, were isolated from the α-amylase limit phosphodextrin of potato starch by a partial acid hydrolysis and an ion exchange chromatography on Dowex-1 × 8 formate resin. From the quantitative yields of glucose 3-phosphate and glucose 6-phosphate, the distribution of esterified phosphate in potato starch was estimated to be 38% on the C-3, and 61% on the C-6 of glucose residues. it was suggested from a kinetic study that approximately 1% of the phosphate in starch existed in a form more labile to acid than glucose 3-phosphate, possibly as glucose 2-phosphate.     

Characterization of the Pasting,Flow and Rheological Properties of Native and Phosphorylated Rice Starches

Phosphorylation of rice starch and its effects on the physiochemical properties of the starch were investigated. Phosphorylation was conducted using the oven heating method by heating mixtures of rice starch and monosodium dihydrogenphosphate at 120‐150°C for 0.5‐2 h, and the pasting, flow and rheological properties of the resulting starch phosphates were analyzed. Phosphorylation with substitution degrees of up to 0.12 was achieved by raising the reaction temperature to 140°C, but further increase in the temperature to 150°C caused a marked reduction in the degree of substitution. Phosphorylation resulted in significant declines in pasting temperature and setback, but increases in peak viscosity and breakdown. Suspensions of rice native starch and starch phosphates were shown to be non‐Newtonian, pseudoplastic fluids, exhibiting typical shear thinning. They also exhibited yield stress, the magnitude of which increased with the degree of phosphate substitution. Dynamic testing showed that phosphorylation resulted in a decrease in the temperature at which storage and loss moduli (G′ and G″) reached a peak during heating and a reduction in G′ during cooling. These results appeared to indicate that phosphorylation improved the shear stability of rice starch pastes and enhanced swelling of starch granules, but impeded starch retrogradation.     

Influence of the naturally occurring phosphate esters on the crystallinity of potato starch

The gelatinisation enthalpy of native potato starch, as measured by DSC, as observed to decrease ith increased natural phosphorylation of the amylopectin. The phosphate esters bound to the C-6 carbons clearly reduced the gelatinisation enthalpy, hereas the phosphate esters bound to C-3 carbons took little or no part in this reduction. Retrograded starch samples ere also studied, in order to find a corresponding relationship beteen the degree of phosphorylation and the recrystallisation enthalpy. These results ere less convincing, but the phosphate esters did tend to increase the retrogradation enthalpy independent of the phosphorylation site.     

Phosphorylation of Corn Starch in an Ionic Liquid

Corn starch was phosphorylated by reaction with sodium dihydrogenphosphate or disodium hydrogenphosphate using 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) as reaction medium. The parameters varied included the molar ratio of reactant, reaction time and temperature and were investigated regarding the degree of substitution for the phosphorylated starch. The degree of substitution of starch phosphates prepared ranged from 0.03 to 0.55. The product was characterized by Fourier‐transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques. It was found that the native crystallinity of corn starch was largely distroyed during the dissolution and functionalization process in the ionic liquid system under the reaction conditions.     

玉米粉丝耐煮配料的研究和应用

本试验采用三因素二次回归正交试验,确定了食盐、明矾、CMC－Na作为玉米粉丝耐煮成分的最佳配比。对不同取代度的淀粉磷酸酯在玉米粉丝中的作用也进行了研究,结果表明,取代度为0．690的淀粉磷酸酯效果最佳,且用量不超过4％。经实验室综合试验和在实际生产中进行试验最终确定了玉米粉丝耐煮配料组成为食盐、明矾、CMC－Na和淀粉磷酸酯,其最佳配比（按100g干淀粉）为0．50g,0.67g,0.20g和3.0g。     

Physicochemical Properties of Ginkgo Kernal Starch

Native starch was isolated from ginkgo kernels, its physicochemical properties were investigated using some physical methods. Ginkgo starch granules were mostly oval in shape with a central Maltese cross and average long axis of 11 μm. Ginkgo starch contained 29.9% amylose content and exhibited an A-type crystallinity with 27.2% crystalline degree. Ginkgo starch had significantly higher gelatinization conclusion temperature, temperature range, and enthalpy than potato and rice starches. Ginkgo starch showed lower hot viscosity and higher breakdown viscosity than potato and rice starches. Ginkgo starch possessed markedly higher swelling power and resistance to α-amylase and amyloglucosidase hydrolysis than rice starch.     

Changes in the structural and physicochemical characterization of pea starch modified by Bacillus-produced α-amylase

In this study, changes in structural and physicochemical properties of pea starch treated with Bacillus-produced α-amylase were determined. The results showed that enzymatically modified pea starch had lower amylose content and granule size but higher branching degree and relative crystallinity. After enzyme hydrolysis, the distribution of A and B1 chains slightly decreased, while the distribution of B2 and B3 chains increased lightly. Enzymatic hydrolysis preferentially occurred in the amorphous region and cannot change the crystalline structure of pea starch. Moreover, pea starch showed lower light transmittance, peak viscosity, breakdown viscosity, pasting temperature, shear viscosity, storage modulus and loss modulus, while the oil adsorption capacity and gelatinization enthalpy significantly increased with increasing α-amylase hydrolysis time. Correlation analysis indicated that α-amylase hydrolysis had different effects on different pea varieties. This research could provide ideas for exploring new applications for enzymatically modified pea starch in food industry.Industrial relevanceThis study found that Bacillus-produced α-amylase significantly changed the amylose content, granule size and viscosity of pea starch, which was helpful to further investigate the modified starch. This technology is expected to widen the applications of pea starch modified by Bacillus-produced α-amylase in food industry, for example as thickener, stabilizer and beverage, to improve the texture, stability and shelf-life of various food products.     

Effect of Inorganic Phosphates on the Adhesion of Mono‐phosphorylated Cornstarch to Fibers

The influences of inorganic phosphates, as residuals and/or impurities within starch, on the adhesion of acid‐treated cornstarch phosphates to cotton and polyester fibers were investigated for warp sizing. The phosphate impurities considered included sodium dihydrogenphosphate, sodium hydrogenphosphate, sodium pyrophosphate, and pentasodium triphosphate. The starches with a phosphate degree of substitution (DS) range of 0.004‐0.021 were phosphorylated by heating acid‐treated cornstarch at 125°C for 90 min in a solid‐state reaction with pentasodium triphosphate. The adhesion was evaluated in terms of the breaking strength and work‐to‐break of slightly sized rovings. It was found that the phosphorylation improves the adhesion to both fibers even at a low phosphorylation extent. The phosphate impurities within starch have an adverse effect and reduce the adhesion to both fibers. The adverse effect depends on the type and level of the phosphates, decreasing in the series NaH₂PO₄ > Na₂HPO₄ > Na₄P₂O₇ ≈ Na₅P₃O₁₀. The adhesion enhances as the DS increases and as the free phosphate content decreases. Furthermore, the adverse effect can be offset by the phosphate modification of starch.     

Effect of the Heat-Moisture Treatment on the Enzymatic Susceptibility of Corn Starch Granules

Normal and waxy corn starches were isolated, adjusted to different levels of moisture and heated at 100°C for 16h. The heat treated starches were hydrolysed with α-amylase and amyloglucosidase. The starch samples were studied by determining their water-binding capacity, pasting properties, X-ray diffraction and by optical and scanning electron microscopy. The results showed that the heat-moisture treatment produced an increase in the degree of crystallinity of normal and waxy corn starches at the level of 18% moisture. This result, in conjunction with a significant decrease in the enzymatic susceptibility, suggested a rearrangement of the starch molecules with strengthening of the linkages within the granules. On the other hand, the heat-moisture treatment caused a rupture with further rearrangment of linkages within the granules for normal and waxy corn starches adjusted to the 27% moisture level. This produced a certain degree of starch degradation increasing the accessible regions of the granule to amylolysis.     

加酶挤压对小麦淀粉结构和理化性质的影响

本文旨在探究加酶挤压对小麦淀粉结构和理化性质的影响。分别设置浓度梯度为0%、0.1%、0.2%、0.5%、1%、2%的α-淀粉酶-小麦淀粉混合物样品,挤压处理后,利用扫描电镜（SEM）、差示扫描量热仪（DSC）、X-射线衍射仪（XRD）、快速粘度仪（RVA）等分析淀粉结构与理化性质的变化。结果表明:各处理组的堆积密度无显著差异（P>0.05）;吸水指数与加酶量呈负相关,水合指数与加酶量呈正相关;挤压后淀粉糊化度均大幅度提高,接近完全糊化;挤压后淀粉的颗粒结构被完全破坏且加酶使得淀粉颗粒粒径更小;加酶挤压处理后相对结晶度降低,从原淀粉的17.52%降至10.29%（酶浓度2%）;挤压处理后小麦淀粉的糊化焓均显著下降（P<0.05）,挤压淀粉样品焓值最低,仅为0.24 J/g,加酶挤压淀粉的焓值高于挤压淀粉,随着加酶量的增加,淀粉的焓值上升至2.5 J/g左右;RVA曲线可明显看出处理组的粘度远低于原淀粉粘度,且加酶挤压样品粘度低于不加酶挤压粘度。本文探明了加酶挤压对淀粉结构和理化性质的作用规律,可为加酶挤压技术在淀粉基食品领域的应用提供理论指导。     

Preparation of Starch Phosphates by Extrusion

Physicochemical properties were compared on starch phosphates of cassava and corn, prepared by an extrusion process and by the conventional method, as well as their native starches. Results indicated that for preparing starch phosphates with similar degrees of substitution, the extrusion process required less reagent than the conventional method. The starch phosphates showed similar responses to heat treatment and pH changes. However, the starch phosphates made by extrusion had lower gelatinization temperatures, lower enthalpies and lower paste viscosities than those prepared by the conventional method. This result could be attributed to the high degree of damaged starch in the extruded products.     

Characterization of Acetyl Starch by Means of NMR Spectroscopy and SEC/MALLS in Comparison with Hydroxyethyl Starch

The properties of starch derivatives which may be used as plasma substitutes, are dependent upon the molecular structure. Seven acetyl starch (AS) samples were determined and compared with results from hydroxyethyl starch (HES) samples. The molar masses and their distributions were determined with the combination of size exclusion chromatography and light scattering. Slightly asymmetric distributions were determined with a polydispersity M_w/M_n = 2.4 and weight-average molar masses of M_w = 250,000–300,000 g/mol for six AS samples and M_w/M_n = 3.6 and a weight-average molar mass of 766,000 g/mol for one AS sample. The average degrees of substitution (DS) and the substitution pattern were determined by high resolution NMR spectroscopy. The AS samples investigated had a DS of 0.42 to 0.81, comparable to HES, but the regioselective substitution pattern revealed differences. While for HES the position C-2 is preferred and the position C-3 has nearly no substituent, for AS both positions, C-2 and C-3, are substituted likewise. Degradability by α-amylase was tested in the laboratory for AS as well as for HES having nearly the same degree of substitution and molar mass, but C-2/C-6 = 2 for AS and C-2/C-6 = 1.4 for HES. An exponential decrease in the molar mass was observed over time, down to a limiting molar mass M_w = 50,000 g/mol for AS and M_w = 30,000 g/mol for HES, the degradation of AS occurred more slowly.     

The Effects of Enzyme Hydrolysis on the Properties of Potato,Cassava and Amaranth Starches

X-ray diffraction method and differential scanning calorimetry were used to study the effects of enzyme hydrolysis on physico-chemical properties of potato, cassava and amaranth starches. Various hydrolysis procedures and different sources of enzymes were employed. The highest percentage of hydrolysis was obtained using the bacterial thermostable α-amylase following by the saccharification with amyloglucosidase. Enzyme treatment showed decrease in the degree of crystallinity of all hydrolyzed starch samples of A-type crystals. B-and C-types were weakened upon enzymatic hydrolysis at 60°C and completely dissappeared at 100°C. The gelatinization endotherm decreased for samples with low degree of crystallization and disappeared in samples with amorphous stage.     

Dielectric barrier discharge plasma improved the fine structure,physicochemical properties and digestibility of α-amylase enzymatic wheat starch

Plasma is growingly used in the modification of starch granules as an emerging non-thermal technology. The study was aimed to investigate the improving role that the plasma process plays in the structure, physicochemical and functional properties of enzymatic starch. Therefore, this work modified wheat starch by α-amylase (20, 40 and 60 U/mL), assisted by post-processing plasma technology for different durations (2, 6 and 10 min). When the plasma and α-amylase were applied to wheat starch, respectively, the molecular weight, amylopectin side chains, crystallinity, R_1047/1022 value, swelling power and pasting viscosity decreased significantly. In contrast, the gelatinization temperatures, enthalpy and resistant starch (RS) enhanced particularly compared with the native starch. Notably, enzymatic starch assisted by plasma post-treatment exhibited more severe surface damage and lower crystallinity, short-range order, more linear short chains, and higher RS content than single modified starch. Furthermore, the principal components analysis indicated that the physicochemical characteristics of starch were highly connected with the change of the molecular structure. Thus, the α-amylase hydrolysis combined with the plasma process exhibited a remarkable ability to modify starch with new characteristics and can be used to produce food with low digestibility.     

糯米淀粉的晶体性质和糊化特性

以不同产地、品种的糯米为原料,探讨糯米淀粉晶体性质和糊化特性的差异,并进行相关性分析,以期为糯米食品加工的原料选择提供参考。试验结果表明,糯米淀粉的结晶度为16.4%~25.3%,糊化温度为71.1~87.2℃,且结晶度和糊化温度均以珍珠糯最高,禾胜糯1次之,扬丰糯最低。其中,结晶性质主要取决于品种,受产地影响相对较小,而产地、品种的差异极大地影响糯米淀粉的糊化性质。相关性分析表明,糯米淀粉的碘蓝值、结晶度与糊化温度三者之间呈极显著正相关关系。因此,品种和产地对糯米淀粉的结晶性质和糊化特性均有较大影响。     

高取代度阳离子淀粉在精制牛皮纸生产中的应用实践

用玉米淀粉与3—氯—2—羟丙基三甲基氯化铵(CHPTMA)为原料,通过预干燥干法制得高取代度季铵型阳离子淀粉醚,经洗涤抽滤制得不含氯离子的高取代度阳离子淀粉(C-2阳离子淀粉)代替普通阳离子淀粉应用在精制牛皮纸的生产中。结果表明,它能有效提高精制牛皮纸的物理性能和使用性能,提高产品的强度等级,起到很好的增强效果。同时节约了原料并降低了生产成本,为企业带来经济效益。     

Effect of Phytate and Other Myo-inositol Phosphate Esters on α-Amylase Digestion of Starch

The effects of phytate and other myo-inositol phosphate esters (containing one or more phosphate groups) on α-amylase digestion of soluble potato starch were evaluated by an in vitro procedure. Human salivary or Bacillus subtilisα-amylase was treated with either 2 mM or 5 mM phytate, myo-inositol-2-monophosphate (l–2-MP), or phytate hydrolyzed to various degrees, and then incubated at 37°C with the starch at pH 4.15 or 6.90. Starch digestion varied with degree of phosphorylation of inositol, inositol phosphate ester concentration, pH and enzyme source. At pH 4.15, phytate (2 mM) and I-2-MP (2 mM) reduced starch digestion by salivary α-amylase to 8.5 and 78.3%, respectively, of the control.     

交联微孔淀粉的制备及其性能研究

以木薯淀粉为原材料,三氯氧磷（POCl3）为交联剂,糖化酶与α-淀粉酶为复合酶,采用一次法和两次法制备了交联微孔淀粉.测定了交联微孔淀粉的吸水率和吸油率,利用扫描电子显微镜（SEM）和X射线衍射（XRD）对交联微孔淀粉进行了性能表征.结果表明：与一次法相比,两次法制备的交联微孔淀粉吸附能力提高了很大的提升,当POC13用量为0.4μL/g时,吸水率和吸油率分别增加了9.22％和10.43％.SEM观察到交联微孔淀粉表面有较多孔洞,微孔化程度高;XRD结果发现交联微孔淀粉的结晶度降低.     

酸解对不同链/支比含量玉米淀粉特性的影响

以4种不同链/支比含量的玉米淀粉为原料,酸解处理不同时间,以酸解玉米淀粉的形貌特性、冻融稳定性、膨胀度、溶解度、晶体性质为指标衡量不同酸解时间对玉米淀粉结构性质的影响。结果表明:4种玉米淀粉酸水解程度的顺序为:蜡质玉米普通玉米淀粉G50G80。酸解后,同品种的4种玉米淀粉的析水率随着酸解天数的增加而增加;溶解度增加,膨胀度降低。酸解并未改变淀粉的晶型,随着酸解时间的延长,蜡质玉米淀粉和普通玉米的相对结晶度先增大后保持不变,G50和G80的相对结晶度随着酸解时间的增加而增大。表明酸解对低直链淀粉(蜡质玉米淀粉和普通玉米淀粉)的结构、性能影响最大。