Effect of controlled gelatinization in excess water on digestibility of waxy maize starch

An aqueous dispersion of waxy maize starch (5%, w/w) was controlled gelatinized by heating at various temperatures for 5 min. The treated samples were analysed using in vitro Englyst assay, light microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared spectroscopy. When heated, SDS and RS levels were decreased inversely with RDS. A high SDS content (>40%) was kept prior to the visible morphological and structural changes (before 60 °C). Swelling factor began to increase slightly at 50–60 °C and continued to maximum value at 80 °C. A large decrease in ΔH, crystallinity, and ratio of 1047/1022 cm⁻¹ attributed to partially dissociation of crystalline clusters and double helices occurred at 65–80 °C. These changes showed that controlled gelatinized starch with slow digestion property occurred in the molecular rearrangement process before granule breakdown and SDS mainly consists of amorphous regions and a small portion of less perfect crystallites.     

Structural characterizations and digestibility of debranched high-amylose maize starch complexed with lauric acid

Structural characterizations and digestibility of debranched high-amylose maize starch complexed with lauric acid (LA) were studied. The cooked starch was debranched by using pullulanase and then complexed. Light microscopy showed that the lipids complexed starches had irregularly-shaped particles with strong birefringence. Gel-permeation chromatograms revealed that amylopectin degraded to smaller molecules during increasing debranching time, and the debranch reaction was completed at 12 h. Debranching pretreatment and prolonged debranching time (from 2 h to 24 h) could improve the formation of starch lipids complex. X-ray diffraction pattern of the amylose–lipid complexes changed from V-type to a mixture of B- and V-type polymorphs and relative crystallinity increased as the debranching time increased from 0 to 24 h. In DSC thermograms, complexes from debranched starch displayed three separated endotherms: the melting of the free lauric acid, starch–lipid complexes and retrograded amylose, respectively. The melting temperature and enthalpy changes of starch–lipid complex were gradually enhanced with the increasing of debranching time. However, no significant enthalpy changes were observed from retrograded amylose during the starch–lipid complex formation. Rapidly digestible starch (RDS) content decreased and resistant starch (RS) content increased with the increasing of debranching time, while the highest slowly digestible starch (SDS) content was founded at less debranching time of 2 h. The crystalline structures with dense aggregation of helices from amylose-LA complex and retrograded amylose could be RS, while SDS mostly consisted of imperfect packing of helices between amylopectin residue and amylose or LA.     

Impact of mild acid hydrolysis on structure and digestion properties of waxy maize starch

In this study, the molecular structure of acid-treated waxy maize starch residues was investigated, and the in vitro digestibility of the residues with 2.2 N HCl at 35 °C for different time periods, was assessed. The granular appearance of waxy maize starch was destroyed and small fractions formed aggregates. A change in chain-length distribution profiles occurred with the degradation of shortest A chains and long B chains in amylopectin. The rise in the ratio of absorbance height at 1047 cm⁻¹ to the height at 1022 cm⁻¹, the intensities of major peaks, X_c, T_p, T_c, and ΔH were observed during mild acid hydrolysis, but the X-ray diffraction patterns displayed A-type for all starches. The amount of rapidly digestible starch increased, whereas the amounts of slowly digestible and resistant starch decreased. These results demonstrate that the amorphous regions of starch granules, including the shortest A chains and long B chains, are preferentially hydrolysed and affect the slow digestion and resistance properties of waxy maize starch.     

Slowly digestible starch from heat-moisture treated waxy potato starch: Preparation,structural characteristics,and glucose response in mice

Heat-moisture treatment (HMT) was optimised to increase the formation of slowly digestible starch (SDS) in waxy potato starch, and the structural and physiological properties of this starch were investigated. A maximum SDS content (41.8%) consistent with the expected value (40.1%) was obtained after 5 h 20 min at 120 °C with a 25.7% moisture level. Differential scanning calorimetry of HMT starches showed a broadened gelatinization temperature range and a shift in endothermal transition toward higher temperatures. After HMT, relative crystallinity decreased with increasing moisture level and X-ray diffraction patterns changed from B-type to a combination of B- and A-types. Hollow regions were found in the centres of HMT waxy potato starches. HMT intensity significantly influenced SDS level. This study showed that HMT-induced structural changes in waxy potato starch significantly affected its digestibility and the blood glucose levels of mice who consumed it.     

Physicochemical characteristics of waxy rice starch influencing the in vitro digestibility of a starch gel

Starches were isolated from three waxy rice varieties: Koganemochi (Kog), Hakuchomochi (Hak), and Kantomochi 172 (K172). Forty percent starch gels were prepared and the extent of starch gel digestibility was determined by an in vitro method. The distribution of chain lengths of amylopectin was analyzed and differential scanning calorimetry was used to analyze gelatinization and retrogradation of waxy rice starch. The K172 gel had significantly higher resistance to hydrolysis than had the other gels. The K172 starch contained lower proportions of the short chains of amylopectin and showed higher gelatinization temperature and enthalpy. The retrogradation peak was measured using waxy rice starch gels stored for 1 and 7 days at 5 °C. The K172 gel was observed to retrograde more quickly and to have a greater extent of retrogradation than the other gels. The difference in amylopectin chain length distribution and recrystallinity contributed to the variation in the starch gel digestibility of waxy rice.     

Preparation and properties of RS III from waxy maize starch with pullulanase

Waxy maize starch was treated by pullulanase debranching and retrogradation at room temperature to produce resistant starch (RS). Physicochemical properties, crystalline structure and in-vitro digestibility of starch samples with different RS content were investigated. Compared with native starch, apparent amylose content of RS products increased. Based on Gel Permeation Chromatography (GPC) the Molecular Weight Distribution (MWD) of resistant starches significantly changed. Scanning Electron Microscopy (SEM) showed that upon pullulanase debranching and retrogradation treatment the granular structure of native starch was destroyed and all RS samples exhibited irregular shaped fragments. Crystal structure of samples changed from A–type to a mixture of B and V–type. The crystallinity of resistant starch also improved as compared with native starch. Moreover, samples with higher resistant starch showed higher relative crystallinity. Differential Scanning Calorimetry (DSC) determination showed that To、Tp、Tc and ΔH all increased which was in agreement with RS content. The resistance of waxy maize starch with Pullulanase treatment to α-amylase digestibility also increased, while the in-vitro digestibility of products decreased.     

Temperature-dependent quality characteristics of pre-dehydrated cookies: Structure,browning, texture, in vitro starch digestibility,and the effect on blood glucose levels in mice

The purpose of this study was to elucidate the physical and biochemical properties of pre-dehydrated cookies baked at various temperatures. Cookie dough was vacuum-dried, and then baked at 120–180 °C for 18 min. All samples showed lower spread ratio than non-dehydrated cookie baked at 180 °C (control). Browning of the samples baked at 180 °C and 160 °C was higher than that of the control. In contrast, little browning was observed in the sample baked at 120 °C. The fracture force of samples baked at 140 °C and 120 °C agreed well with the control. From these results, the sample baked at 140 °C was employed for subsequent studies. In vitro starch digestibility suggested that the sample baked at 140 °C had higher slowly digestible starch content than the control. From postprandial blood glucose levels in mice, it was found that the sample significantly reduced the blood glucose peak observed at 30 min post-administration.     

高透明度氧化蜡质玉米淀粉性质研究

研究氧化蜡质玉米淀粉颗粒形态、偏光性质、透明度、凝沉性等性质,并与其原淀粉相比较;结果表明,在相同氧化条件下,氧化蜡质玉米淀粉羧基含量要比氧化普通玉米淀粉低;其颗粒外观形状与蜡质玉米淀粉相似,偏光十字清晰,氧化作用发生在无定型区;氧化蜡质玉米淀粉颗粒表面更为粗糙,微孔洞量增加,氧化反应在淀粉颗粒表面和内部进行,颗粒表面发生降解;比其原淀粉显示更高透明度,而凝沉效果相差不大。     

Effect of endosperm type on texture and in vitro starch digestibility of maize tortillas

Tortilla is the main staple of Mexico and it is made using diverse maize varieties, which have different endosperm types. Three maize varieties with vitreous, intermediate and floury endosperms were used. Texture and starch digestibility were evaluated in freshly prepared and stored tortillas for 24, 48 and 72 h. Tortilla made with maize of vitreous endosperm had the highest force to rupture and the lowest distance of elongation, indicating more rigid texture. Stored tortillas had lower available starch content and higher effect was shown by tortilla of vitreous endosperm, pattern that agrees with the higher increase in the resistant starch content with the storage time. Fresh tortilla of floury endosperm showed the highest hydrolysis rate during the first 15 min followed by tortillas of intermediate and vitreous endosperms. Starch hydrolysis values decreased when storage time increased, in agreement with the resistant starch content in the stored tortillas. At the longest storage time (72 h) tortilla of floury endosperm presented higher hydrolysis rate, followed by tortilla of intermediate and vitreous endosperms. The endosperm type plays an important role in the textural and starch digestibility of fresh and stored tortillas.     

糯玉米淀粉及其改性淀粉在食品工业中的应用

介绍了糯玉米淀粉及其变性淀粉在制糖、酿造、食品、粘合剂生产等方面的应用。     

玉米交联羟丙基复合变性淀粉性能研究

以糯玉米淀粉为原料,环氧丙烷为醚化剂、三偏磷酸钠为交联剂、氢氧化钠为催化剂、无水硫酸钠为膨胀抑制剂,采用湿法工艺制备不同取代度和交联度的交联羟丙基复合变性淀粉,并对复合变性淀粉的耐酸性、耐盐性、透明度、冻融稳定性特性指标进行对比研究。结果表明:复合变性淀粉的透光率、耐酸性、耐盐性、冻融稳定性受产品取代度和交联度影响较大,耐酸性、耐盐性、冻融稳定性随着取代度的升高而增强,透光率随着交联度的升高而降低。     

Synthesis,characterisation and in vitro digestibility of carboxymethyl potato starch rapidly prepared with microwave-assistance

Carboxymethyl potato starch was synthesised with the aid of microwave. Optimal degree of substitution (DS) of 0.32 was obtained at 45 °C in 25 min using aqueous ethanol media with water/solvent of 0.15 at 200 W. The molar ratio of sodium hydroxide and monochloroacetic acid to anhydroglucose unit for optimal DS were 2.5 and 1.0, respectively. FT-IR spectrometry revealed the carboxymethyl starch to show new bands at ν = 1614 cm⁻¹ and ν = 1429 cm⁻¹. Wide angle X-ray diffractometry and DSC revealed a remarkable reduction in starch crystallinity after carboxymethylation, which was consistent with destroyed surface observed in SEM. The digestibility of carboxymethyl starch (CMS) was lower than that of native starch. With similar DS, there was no difference in digestibility of carboxymethyl starch prepared with and without microwave. As DS increased from 0.05 to 0.32, the amount of resistant starch in microwave-assisted carboxymethyl starch was elevated from 14.6% to 20.0%, which was much higher than that of native starch (10.8%).     

普鲁兰酶加酶量对蜡质玉米抗性淀粉影响及性质研究

选用蜡质玉米淀粉为原料,高温糊化后采用普鲁兰酶脱支,产生短直链淀粉,重新结晶制备抗性淀粉。结果表明,8%(w/w)淀粉乳添加20 ASPU/g(基于淀粉干基重)普鲁兰酶在58℃反应24 h,然后在20℃凝沉24 h产生样品抗性淀粉含量最高,达到27.69%。理化性质研究表明,所有抗性淀粉样品颗粒形貌遭到破坏,形成不规则碎片;X-射线衍射图谱均有新的结晶结构出现,显示为B+V型;DSC分析结果显示,随抗性淀粉含量增加,不同样品峰值温度和糊化焓也增加。     

羟丙基糯玉米淀粉的制备及其性质的研究

以糯玉米淀粉为原料,环氧丙烷为醚化剂,在碱性条件下对羟丙基淀粉的制备工艺及其性质进行了研究。通过单因素实验考察了醚化剂、膨胀抑制剂、pH值、反应温度、反应时间对羟丙基淀粉取代度和反应效率的影响。实验结果表明,淀粉用量为100 g时,最佳反应条件为:pH11.5,硫酸钠12 g,环氧丙烷12 g,反应温度50℃,反应时间20 h。随着羟丙基糯玉米淀粉取代度的增加,其冻融稳定性、透明度、耐酸性和热稳定性都增强。     

Influence of milk proteins on the pasting behaviour and microstructural characteristics of waxy maize starch

Gelatinisation of 5 wt% waxy maize starch (WMS) under shear (16.8 s⁻¹), alone and in mixtures with 5 wt% α-lactalbumin (α-lac), β-lactoglobulin (β-lg), α-caseinate or β-caseinate, showed reinforcement of the starch granule structure by both caseinates, but not by the whey proteins (α-lac and β-lg). Reinforcement was evident from (i) later onset of increase in viscosity on heating; (ii) higher gelatinisation temperature by differential scanning calorimetry; (iii) micrographs showing reduced swelling during heating and in the final pastes obtained on cooling; and (iv) elimination of a characteristic “secondary swelling peak” observed for WMS immediately after completion of heating to 95 °C and attributed to fracture of a restricting layer of lipid and protein at the surface of the granules. A likely mechanism of reinforcement is binding of caseinate to the lipid–protein layer. Images from confocal laser scanning microscopy with fluorescent labelling of protein showed attachment of aggregated β-caseinate to the surface of WMS granules in mixtures that had been heated (under shear) to 70 °C. Corresponding images for mixtures with α-caseinate (which is less aggregated) showed penetration of protein to the interior of the granules, which would allow binding to occur on the inside of the surface layer as well as the outside. The inability of the more hydrophilic whey proteins to reinforce the WMS granules suggests that binding of caseinates to the lipid–protein layer occurs predominantly by hydrophobic association. The understanding that caseinates make gelatinised WMS granules smaller and tougher could be useful in product formulation.     

羟丙基糯玉米淀粉的制备及其性质的研究

以糯玉米淀粉为原料,环氧丙烷为醚化剂,在碱性条件下对羟丙基淀粉的制备工艺及其性质进行了研究.考察了醚化剂、膨胀抑制剂、pH、反应温度、反应时间对羟丙基淀粉取代度和反应效率的影响.实验结果表明,随着pH的增大,羟丙基淀粉的取代度和反应效率都增大;提高反应温度,羟丙基淀粉的取代度和反应效率都增加;增加环氧丙烷的用量,羟丙基淀粉的取代度随之增加,但反应效率呈下降的趋势;延长反应时间,淀粉的取代度和反应效率都呈上升趋势;增加硫酸钠的用量,羟丙基淀粉的取代度和反应效率都先增大,当硫酸钠用量超过12g时,随着硫酸钠用量的增加取代度和反应效率都降低.并且确定出最佳的反应条件:淀粉用量为100g时,pH为11.5,膨胀抑制剂12g,环氧丙烷10mL,反应温度50℃,反应时间20h.随着羟丙基糯玉米淀粉取代度的增加,其冻融稳定性、透明度、耐酸性、黏度热稳定性都增加.     

脱支处理蜡质玉米淀粉分子重排形成纳米结晶微球的研究

利用脱支酶对蜡质玉米淀粉进行不同程度的脱支处理,形成不同分子分布的产物,研究产物中分子结构对结晶体形成及结构的影响。SEM显示随着脱支程度的增加结晶体由棒状网络结构逐渐过渡为完美的球状颗粒,FTIR分析发现该结晶体内部分子排列的有序性也是随着脱支程度的增加而升高,说明与淀粉大分子相比,小分子更易趋于有序排列,而脱支产物中大分子的存在会影响重结晶方式,导致结晶体形态、得率和晶型的不同。     

酸预处理对蜡质玉米乙酰化淀粉性质的影响

以蜡质玉米淀粉为原料,采用先酸顸处理再进行乙酰化改性的方法制备酸解乙酰化复合改性淀粉,研究了酸预处理对淀粉黏度、透明度、膨胀度等理化性质的影响并用傅里叶变换红外光谱仪和X射线衍射仪对改性淀粉的结构进行分析。结果表明：酸预处理后,改性淀粉的黏度显著降低,起始糊化温度高于乙酰化淀粉但低于酸解淀粉,冷、热糊稳定性与糊的抗凝沉性增强;酸预处理降低了复合改性淀粉的膨胀度,提高了透明度,溶解度显著增加且随着酸浓度的增加而增加;低浓度酸处理对改性淀粉的冻融稳定性影响较小,高浓度降低改性淀粉的冻融稳定性：酸预处理对改性淀粉的结晶结构影响较小,没有破坏改性淀粉的基本结构。     

蜡质玉米淀粉的双重酯化改性及其在油脂微胶囊化中的应用

以蜡质玉米淀粉为原料,经乙酸酐乙酰化和辛烯基琥珀酸酐酯化得到乙酰化取代度为0.0768,酯化取代度为0.0284的乙酰化辛烯基琥珀酸淀粉酯。将合成的乙酰化辛烯基琥珀酸蜡质玉米淀粉酯作为乳化剂应用于油脂微胶囊化中,制备出包埋率达95.71%的粉末油脂产品。