Change in Digestibility of Gamma-Irradiated Starch by Low Temperature Cooking

Combination effect of irradiation and low temperature cooking on starch digestibility has been investigated as a basic research for application of radiosterilization on starch fermentation. The digestion of corn starch by glucoamylase after cooking at low temperature was enhanced by γ-irradiation and the required cooking temperature was decreased from 75-80°C to 65°C by 25 kGy. Gelatinization of starches except tapioca starch was enhanced by irradiation and it corresponds to the digestibility. The digestibility of potato starch which has a high viscosity was especially enhanced at low temperature cooking because the viscosity was markedly decreased by irradiation. These results show that the irradiation of starches is useful not only for the sterilization of fermentation broth but also for the enhancement of digestion.     

Distinctive Sorghum Starch Granule Morphologies Appear to Improve Raw Starch Digestibility

Various factors, including starch granule channels, have been suggested to contribute to the control of sorghum starch digestibility for animal feed. Isolated starch from two normal sorghum lines (P721N, IS6986) and one high protein digestibility (HPD) mutant line (111) that differed in starch granule morphology were selected to study the influence of these factors on starch digestibility. Scanning electron micrographs were taken of raw and digested starches. Microscopy results confirmed that in all three sorghum lines channels in starch granules are the main route of enzyme penetration and the central cavity area is the starting point of enzyme digestion. Channel density was more pronounced in the HPD sorghum mutant line than in normal lines, which may have been responsible for its relatively high digestibility. Micrographs of IS6986 showed unique starch granule morphology with a collapsed ”doughnut‐shaped” structure in a portion of the granules. These unusual granules were rapidly digested and, unlike normal spherical granules, totally disappeared after 30 min of digestion. Amylases appeared to have fast access to the collapsed‐appearing starch granules. Digestion profiles, following incubation with pepsin and α‐amylase, showed that IS6986 and the HPD mutant (111) had the highest initial rate of starch digestion, followed by P721N. These findings provide insight as to how new sorghum cultivars might be developed with high starch digestibility for animal feed use.     

Non-Starch Polysaccharides and in Vitro Starch Digestibility of Raw and Cooked Chick Peas

The effects of domestic and industrial cooking methods on the non-starch polysaccharides (NSP) content and in vitro starch digestibility of chick pea (variety “blanco lechoso”) have been studied. Total and soluble NSP increased, as did the slowly digestible starch (SDS), whereas the resistant starch (RS) fraction decreased after cooking, showing higher content in domestic than industrially cooked chick peas. The in vitro starch digestible rate index (SDRI) was similar in the cooked chick peas, as was the rapidly available glucose (RAG). Due to the low values of RAG, chick peas would give a slow post-prandial glycaemic response. Domestic cooked chick peas consumption would increase the intakes of RS in human diet, whereas the industrially cooked chick peas with lower content of RS would result in less flatulence problems.     

Digestibility of Sweet Potato Raw Starches by Glucoamylase

Three crude glucoamylase preparations from Rhizopus sp., Chalara paradoxa and Aspergillus sp. K-27 were used to determine the digestibility of raw starches from eight sweet potato varieties. Granule sizes and amylose contents were also measured. The average granule sizes ranged between 10.5 and 14.2 μm. The amylose contents varied between 18.2 and 21.8%. The hydrolysis rates for the raw starches by any of the three glucoamylases were similar. However, starch of the variety Hi-starch had a slightly lower hydrolysis rate than other starches when Rhizopus sp, enzyme was used.     

Starch Structure and Digestibility of Rice High in Resistant Starch

Starch digestibility and starch structure of a high‐resistant starch (RS) rice (RS111) was compared to that of a wild rice type (R7954). RS111 exhibited high RS content and incomplete starch hydrolysis in both cooked rice and retrograded rice flour. High RS rice RS111 had a higher λ_max of absorbance and blue value of iodine‐binding starch complex and contained a higher percentage of intermediate chains of amylopectin than R/954. X‐ray diffraction pattern of RS isolated from cooked high RS rice displayed a mixture of B‐ and V‐type that was more resistant to starch hydrolysis by alpha‐amylase. Resistant starch in RS111 is composed mainly of linear amylose and some low‐molecular‐weight amylopectin.     

淀粉消化性分析研究进展

淀粉的消化性与淀粉的营养价值密切相关,因此淀粉的体外和体内消化性越来越多的受到人们的关注。本文综述了近年来国内外有关淀粉消化性的研究进展,主要介绍了影响淀粉消化性能的内在因素和外在因素,以及淀粉消化性能的分析测定方法。     

杂粮淀粉在仔猪体内的消化率研究

以60 日龄生长猪为动物模型,考察4 种不同杂粮原料中淀粉(总淀粉、直链和支链淀粉、抗性和非抗性淀粉)的含量及其在生长猪回肠末端和粪中的表观消化率。结果表明：以干物质为基础,各种杂粮淀粉的含量因杂粮种属不同而差异较大。芋头淀粉和木薯淀粉的回肠末端消化率均显著高于(P ＜ 0.05)土豆和山药淀粉;所有淀粉在粪便中的表观消化率均达99% 以上。芋头淀粉和木薯淀粉因回肠末端消化率高而具有较高的葡萄糖供给效率,土豆淀粉和山药淀粉因后肠微生物的发酵而利用率升高。     

机械活化木薯淀粉及其乙酰化淀粉的消化性能研究

采用In-Vitro 消化模型和美国谷物化学协会(AACC)的76-13 标准方法,以消化速度和抗酶解淀粉含量为评价指标,研究机械活化淀粉及其乙酰化变性处理产品的消化性能和抗酶解性能。结果表明,机械活化对木薯淀粉颗粒的消化性能有显著的强化作用,活化时间越长,消化速率越大,抗酶解淀粉的含量越低。主要原因是机械活化使木薯淀粉紧密的颗粒表面及晶体结构受到破坏,结晶度下降,提高了淀粉颗粒对酶的敏感性,增加反应活性。活化淀粉经乙酰化变性可加快其颗粒的消化性能,降低其糊的消化性能,破坏和阻止抗酶解淀粉的形成,并随取代度提高,淀粉颗粒和糊的消化速度呈下降趋势,抗酶解淀粉含量降低。     

Raw Starch Digestion by Bacillus polymyxa beta-Amylase

Unlike plant ß-amylases, Bacillus polymyxa ß-amylase digests raw starch at a significant rate. The action of this bacterial ß-amylase on raw starch is stimulated greatly by the presence of the debranching enzyme pullulanase.     

Starch Digestibility as Affected by Polyphenols and Phytic Acid

The rate of wheat starch digestibility in the presence or absence of polyphenols (catechin or tannic acid) and/or phytic acid at concentrations found in legumes was determined in an in vitro dialysis system. Addition of tannic acid and phytic acid reduced the starch digestibility 13 and 60% respectively, at 5 hr. Combined tannic and phytic acid reduced the digestibility at a level (63%) which did not differ significantly from that with only phytic acid. Catechin had no significant effect on rate of starch digestibility.     

燕麦全麦粉中淀粉消化性的研究

研究了燕麦β-葡聚糖以及蛋白质对燕麦全麦粉中淀粉消化特性的影响,并对这一影响可能存在的机理进行了探索。燕麦通过磨粉,过筛后,按照颗粒大小分级成了不同的燕麦粉样品。检测表明,不同颗粒大小级别的燕麦粉具有不同质量分数的β-葡聚糖和蛋白质,不同的糊化特性,燕麦的消化速度则随着颗粒的增大而减小。蛋白酶预处理燕麦全粉提高了淀粉的水解速率,但外加β-葡聚糖到消化液中并没有对淀粉原有的消化特性产生显著影响。共聚焦显微镜结果显示,燕麦粉中蛋白质、β-葡聚糖和淀粉可能共同形成了一种聚合结构。因此,燕麦粉固有的β-葡聚糖可能与其他成分,如蛋白质交联而形成一定的空间结构,降低了消化酶与淀粉的接触度,从而延缓了燕麦粉中淀粉的消化。     

Gamma-Irradiation Affects Some Physical Properties of Dry Bean (Phaseolus vulgaris) Starch

Gamma-irradiated great northern (GN) bean starch (2.5–20 kGy) showed apparent increased susceptibility to central fissures. Bean damage during scanning electron microscopy was observed using ≥400OX magnification on GN bean starch samples. Approximate molecular weights estimated by gel filtration chromatography Sepharose Cl-2B of control GN bean starch were: amylopectin >2×10⁶ and amylose 2×10⁵. Amylose-like fraction of irradiated bean starch (20 kGy) revealed two peaks ～6.9×10⁴ and 1.5×10⁵ daltons. Differential scanning calorimetry showed an increase in gelatinization enthalpy and a small increase in gelatinization peak temperature at 20 kGy suggesting a reorganization of the crystalline and amorphous phases of the starch granule.     

淀粉体外消化模型的构建及在交联淀粉消化研究中的应用

在体外对淀粉的消化条件进行仿生模拟,对淀粉的消化产物检测条件进行优化,构建了淀粉体外消化模型。以环氧氯丙烷为交联剂,制备土豆交联淀粉,以构建的体外消化模型,对不同交联度淀粉的消化速度进行研究。结果显示,以恒温振荡培养箱保持37℃恒温,以pH6.9缓冲液维持恒定的pH,以20 r/min的转速振荡模拟肠的蠕动,以透析袋模拟肠,对淀粉的消化可很好的仿生模拟。采用硫酸-苯酚法,消化产物检测的最佳条件为∶波长485 nm,显色温度100℃,显色时间30 min,糖浓度在(0~80)μg/mL范围内线性关系良好,其回归方程为y=0.004 4x-0.005,R2=0.998 8,且样品溶液在2 h内显色稳定。土豆交联淀粉和交联前相比,消化性降低了13.7%~34.5%,且与交联度呈负相关,即交联度越高(沉降积越小),消化性就越低。     

阴米淀粉的颗粒性质及消化性研究

采用电镜扫描、色度仪、X 射线衍射技术对阴米淀粉的颗粒结构、色度、晶体结构进行分析。结果显示,阴米淀粉颗粒结构呈胶体状,晶体结构分散。通过测定淀粉的体外消化率,证明阴米淀粉的消化率比原米淀粉有所提高,快速消化淀粉含量也比原米淀粉有所增加。根据由Goni 等发表于《Nutrition Research》的文章“Astarch hydrolysis procedure to estimate glycemic index”建立的方程式GI=39.71+0.549HI 计算得到淀粉的血糖指数(GI)和水解指数(HI),结果显示血糖指数和水解指数与抗性淀粉含量呈负相关。     

环糊精酶改性对淀粉结构及消化性的影响

淀粉是人类主食的主要组分和能量供应的主要来源,提升淀粉的营养品质对人体健康具有重要价值。酶法改性具有高效、专一性强和符合清洁标签等优势,是提升淀粉品质的重要手段。作者主要研究了环糊精葡萄糖基转移酶（Cyclodextrin glucosyltransferase,CGTase）和环糊精水解酶（Cyclodextrinase,CDase）对玉米淀粉的协同改性效果。分别采用CGTase单独添加、CGTase和CDase同时添加、CGTase和CDase顺序添加3种改性方式,并对改性后淀粉产物的结构以及消化性进行分析。结果表明,双酶改性使得产物中麦芽低聚糖比例显著提升,而对应的环糊精比例显著下降。经3种方式改性后淀粉结构发生明显解聚,DP 13~24、DP 25~36和DP > 37的链长比例下降,而DP < 13的链长比例显著提升。此外,酶改性显著提升了抗性淀粉组分的含量。因此,CGTase和CDase双酶改性在提升淀粉营养品质中具有良好的应用前景。     

响应面试验优化交联马铃薯淀粉制备工艺及体外消化性质研究

以马铃薯淀粉为原料,三偏磷酸钠(STMP)和三聚磷酸钠(STPP)以质量比99:1的比例混合作为交联剂,制备交联马铃薯淀粉。以结合磷含量为指标,交联剂用量、反应pH值、反应温度和反应时间为因素,运用响应面法进行优化,确定最优工艺条件为交联剂用量为淀粉干质量的16%、反应时间4.5h、反应pH11.5、反应温度55℃;在最优工艺条件的基础上,通过改变交联剂用量制备一系列不同结合磷含量的交联淀粉并研究它们的体外消化性质。结果表明,随着交联马铃薯淀粉结合磷含量的增加,其所含的抗性淀粉也随之增加。     

机械活化玉米淀粉及其酯化淀粉的消化性能和抗酶解性能

采用In-Vitro消化模型模拟人体消化环境,对机械活化淀粉及其醋酸酯淀粉的消化速度进行了研究;并用美国谷物化学协会(AACC)的76-13标准方法,测定机械活化淀粉及其醋酸酯淀粉的抗酶解淀粉含量。结果表明,机械活化使玉米淀粉颗粒的消化速度大大加快,抗酶解淀粉的含量降低,且活化时间越长,消化速度越快,抗酶解淀粉的含量越低。醋酸酯化加快了活化淀粉颗粒的消化速度,随取代度的提高消化速度下降,但醋酸酯化降低其糊的消化速度。醋酸酯淀粉中的抗酶解淀粉含量低于活化淀粉,取代度越高含量越低。     

Carbohydrate Digestibility and Resistant Starch of Steamed Bread

Sixteen Australian hard and soft wheats and two U.S. hard wheats were milled into flours (break and reduction) for preparation of steamed breads. Chemical composition and rheological properties of the flour were determined. Steamed breads were analyzed for carbohydrate digestibility and resistant starch. There was no relationship between flour type, protein content and specific volume of steamed breads. Carbohydrate digestibility of steamed breads from soft wheat flour was higher than that of breads from hard wheat flour. Reduction flours produced steamed breads with higher carbohydrate digestibility than break flours. Resistant starch was higher in steamed breads from soft wheat flours than in those from hard wheat flours. Reduction flour produced higher resistant starch levels than break flours. Commercial white bread had resistant starch levels similar to those of steamed breads from soft wheat flour and hard wheat reduction flour.     

Hydrolytic Depolymerization of Starch Raw Materials

The common commercially available starchy sources in India namely cereals like wheat, corn, rice, sorghum were taken for the studies and compared with cassava. Starches from various sources need different type of liquefaction and saccharification procedures. The relative depolymerization procedures with viscosity and oligosaccharide profiles are reported. Rice flour gives very good conversion percentages, but the liquefaction step should be more drastic than other starchy raw materials. Wheat flour, maize flour, and maize starch could be hydrolysed by both acid-enzyme and enzyme-enzyme methods to give good conversion rates. Sorghum starch was found to be most difficult to hydrolyse and gave only 84% conversion.     

辛烯基琥珀酸淀粉酯的制备工艺优化及消化性研究

以糯玉米淀粉为原料,对辛烯基琥珀酸淀粉酯的湿法制备工艺进行了研究,在单因素基础上选取影响取代度明显的三个因素酯化时间、酯化pH、酯化温度上在淀粉乳浓度为40%,酸酐加入量为3%,酸酐用异丙醇稀释6倍的前提下进行响应面设计,得出最佳工艺条件。采用体外酶法消化对不同取代度的糯玉米辛烯基琥珀酸淀粉酯的消化性进行研究,研究结果表明:随着取代度的增加,淀粉体系中的快消化淀粉(RDS)含量显著下降而慢消化淀粉(SDS)与抗性淀粉(RS)含量则明显上升。