不同品种芸豆淀粉及其抗性淀粉结构和物化特性比较

探究不同品种芸豆淀粉、抗性淀粉的结构特征和理化性质。以不同品种芸豆为原料,分别采用碱法和压热酶解法制备芸豆淀粉及其抗性淀粉,利用扫描电镜、傅里叶红外光谱仪、RVA黏度仪等研究不同品种芸豆淀粉和抗性淀粉的分子结构及物化特性。结果表明:与原淀粉相比,抗性淀粉颗粒形貌及晶型结构改变;芸豆淀粉及抗性淀粉官能团和化学键组成相同。红芸豆淀粉糊化温度最低、最终黏度和回生值较高;与淀粉相比,各抗性淀粉糊化温度显著升高,糊黏度降低,芸豆淀粉及抗性淀粉的溶解度和膨胀度均与温度呈正相关,芸豆抗性淀粉的冻融稳定性降低。结论:不同品种芸豆淀粉分子结构特征相同,物化特性不同;压热酶解改变抗性淀粉颗粒形貌及晶型结构;不同品种芸豆抗性淀粉物化特性不同。     

两种菠萝蜜籽抗性淀粉特性研究

本文通过SEM、XRD、DSC和抗酶解性实验对菠萝蜜籽原淀粉和压热处理的菠萝蜜籽抗性淀粉、压热酶解处理的菠萝蜜籽抗性淀粉的特性进行分析。结果表明两种处理过的淀粉样品均失去原淀粉的颗粒外形,压热酶解法处理过的淀粉呈现出大量微孔通道。菠萝蜜籽原淀粉为A型结晶,经过处理后的两种淀粉均为B型结晶。处理过的淀粉与原淀粉相比的T0、TP及ΔH都有所降低;压热处理后的淀粉Tc降低,而经过压热酶解的淀粉Tc值上升。在In-Vitro消化体系中,在同一消化时间长度内,原淀粉的消化产物比两种抗性淀粉的消化产物多,压热酶解抗性淀粉的酶解产物最少,抗性最强。压热和压热酶解让淀粉分子重新组合,改变了淀粉微观结构,提高了淀粉的抗消化性。     

淮山药淀粉及其抗性淀粉理化性质的比较

分析比较了淮山药淀粉及压热法制备的淮山药抗性淀粉的理化性质。结果表明:淮山药淀粉颗粒呈圆形或卵圆形,属C型淀粉;抗性淀粉颗粒为不规则形、多角形,尺寸较原淀粉有所减小。2种淀粉的化学结构相似,与原淀粉相比,抗性淀粉没有生成新的基团。抗性淀粉的溶解度、膨润度、透明度均低于原淀粉,而持水性、乳化性优于原淀粉;糊化温度较原淀粉高,热稳定性和冷稳定性更好。原淀粉糊和抗性淀粉糊均为屈服-假塑性流体,原淀粉糊易剪切稀化,抗性淀粉糊耐机械力的性能好。     

紫山药抗消化淀粉的制备及水解特性*

以酶解-压热法制备紫山药抗消化淀粉,考察了淀粉乳浓度、普鲁兰酶用量、酶解时间、压热时间对制备淀粉中抗消化淀粉含量的影响,通过正交试验和方差分析明确影响因素的重要性并优化工艺条件;比较分析了糊化淀粉、压热淀粉以及酶解-压热法制备淀粉的水解动力学。结果表明:酶解-压热法制备紫山药抗消化淀粉的含量随各因素水平的增加呈先增加后减小的趋势,优化的条件为:淀粉乳质量分数20%、普鲁兰酶用量8 U/g、酶解12 h、以120℃压热处理40 min 2次时,制备抗消化淀粉样品纯度为96.67%,其中抗消化淀粉含量为47.85%;水解特性研究表明:与糊化、压热法相比,酶解-压热法制备抗消化淀粉的水解率、水解指数与血糖指数均显著降低,具有更好的抗消化性。     

压热法制备黑青稞抗性淀粉工艺及性质研究

为探讨黑青稞淀粉在压热改性为抗性淀粉过程中淀粉乳浓度、压热温度、压热时间、冷藏时间等因素对抗性淀粉得率、结构及性质的影响,开发黑青稞抗性淀粉在食品加工中的应用价值。该试验以黑青稞为材料,采用压热法制备抗性淀粉,考察淀粉乳浓度、压热温度、压热时间、冷藏时间对抗性淀粉得率的影响。通过红外光谱分析、扫描电子显微镜及X-射线衍射对抗性淀粉的结构表征,并对部分理化性质进行测定。结果表明,当淀粉乳浓度30%,压热温度125℃,压热时间50 min,冷藏时间24 h时,抗性淀粉的得率为黑青稞抗性淀粉的得率为10.596%。扫描电镜分析表明,与原淀粉相比,黑青稞抗性淀粉的形貌及结晶结构都发生了显著变化,黑青稞原淀粉颗粒呈圆球形,而抗性淀粉呈层片形。X-射线衍射分析表明,淀粉的晶体结构由此前的A型晶体结构转变为抗性淀粉的C型晶体结构。理化性质测试表明,经过压热法制得的黑青稞抗性淀粉溶解度、膨胀度、透光率均降低,持水率升高,且抗性淀粉颗粒粒径变大,结构更加紧密,但化学结构未发生改变。     

怀山药抗性淀粉理化性质及体外消化性研究

分析比较怀山药淀粉和压热法制备的怀山药抗性淀粉的理化性质及消化特性。结果表明:怀山药淀粉颗粒表面光滑,呈不规则且大小不一的椭球形、三角形等形态,属于C型淀粉;抗性淀粉颗粒特征消失,呈现表面疏松的片层状结构。2种淀粉化学结构相似,抗性淀粉没有形成新的基团。与原淀粉相比,抗性淀粉分子量分布更加集中。抗性淀粉的糊化峰值温度高于原淀粉的,因此其热稳定性更高。抗性淀粉的透明度低于原淀粉的。水浴温度低于75℃时,抗性淀粉的持水性大于原淀粉的,而当水浴温度高于原淀粉糊化温度时,原淀粉的持水性明显高于抗性淀粉的;体外模拟人体消化试验表明,抗性淀粉比原淀粉更耐消化。     

压热法结合反复冻融制备小麦抗性淀粉及其理化性质研究

以小麦淀粉为原料,利用压热法制备抗性淀粉,再经过反复冻融,以期提高产品的抗性淀粉含量。对产品的颗粒形貌、碘吸收曲线、持水力、膨胀度、溶解度等理化性质进行了测定。结果表明,反复冻融次数为6次时得到的小麦抗性淀粉含量最高,为18.31%,经过反复冻融处理的小麦抗性淀粉,颗粒呈不规则形,且在碘吸收曲线中稍微偏向直链淀粉吸收峰,表明其可能含有较多的直链淀粉。与小麦原淀粉相比,经反复冻融处理的小麦抗性淀粉的持水力与膨胀度显著增加,而溶解度显著降低。     

山药交联淀粉的制备与表征

为扩大山药淀粉的应用范围,该研究以山药原淀粉为原料,以抗性淀粉含量为指标,通过响应面法优化交联淀粉的制备工艺:反应pH值为10,反应时间为3.3 h,反应温度为48℃,所得交联淀粉中抗性淀粉含量由20%提高到38%。然后,对交联淀粉进行系统表征。结果显示,与山药原淀粉相比,交联淀粉的溶解度、膨胀力、糊透明度、体外可消化性、颜色值、黏附性、弹性、胶黏性与咀嚼性降低,而耐酸性、耐剪切性、冻融稳定性、糊化温度、抗老化性和硬度升高。交联淀粉结构的有序程度下降;晶体仍为A型,相对结晶度有所提高;颗粒形态发生明显变化,少许颗粒发生聚集。因此,山药交联淀粉与原淀粉的性质差异很大,这有助于扩大山药淀粉在食品行业的应用范围。     

酶法联合压热-冷却循环处理制备抗性淀粉

本研究以玉米淀粉为原料,通过酶法联合压热-冷却循环处理制备抗性淀粉,测定酶解过程中淀粉的水解度(DE值)、脱支度和直链淀粉含量、样品抗性淀粉含量及其热稳定性,采用差示扫描量热仪(DSC)、扫描电子显微镜(SEM)分别测定抗性淀粉的热力学特性和颗粒形貌。结果表明,耐高温α-淀粉酶酶解能显著提高淀粉的水解度,耐高温α-淀粉酶联合压热-冷却循环制备的抗性淀粉含量为10.51%~12.16%;淀粉脱支度、抗性淀粉含量、直链淀粉含量随着普鲁兰酶酶解前压热-冷却循环处理次数增加而显著下降,抗性淀粉的热稳定性却得到提高;先普鲁兰酶酶解后压热-冷却循环处理3次得到的抗性淀粉含量最高,达到17.94%;抗性淀粉的糊化峰值温度为119.5℃~121.1℃,糊化焓随抗性淀粉含量的增大而增大,颗粒形状为不规则的碎石型。     

两种抗性淀粉的结构特征及体外消化性研究

本实验对小麦抗性淀粉和马铃薯抗性淀粉结构特征及体外消化性进行研究。结果表明,与小麦抗性淀粉相比,马铃薯抗性淀粉直链淀粉含量更高,分子质量分布更集中,热稳定性更高。两种抗性淀粉粒径相差不大,均为C型结构,化学结构相似,没有基团差异。小麦抗性淀粉分子颗粒完整,表面光滑,呈不规则的椭圆形,马铃薯抗性淀粉分子为不规则多面体,分子表面粗糙,有凹陷,且有少量的层状起伏。体外消化试验表明:马铃薯抗性淀粉具有更强的抗消化能力,血糖指数分别为40.62、40.50（GI<55）,属于低GI食品。相关性分析结果为抗性淀粉体外消化率与其直链淀粉含量、碘吸收峰负相关,与其结晶度、热焓值显著负相关,与比表面积正相关。     

Characterization of Phosphate Monoester Resistant Starch

The properties and structures of corn, wheat, and potato native starches and their phosphate monoester resistant starches were tested and compared. The results indicated that the resistant starch content, light transmittance, and freeze-thaw stability of the phosphate monoester resistant starch increased after modification. The native starches exhibited much higher peak viscosities compared with resistant starch (RS) and phosphate monoester resistant starches. The phosphate monoester resistant starch from corn and wheat starch exhibited a higher peak and final viscosity and lower gelatinization temperatures compared with the resistant starch, while the peak and final viscosity of the potato phosphate monoester resistant starch samples were lower than that of potato resistant starch. In the FT-IR graph, a new peak at 1244 cm^?1 (P=O bond) was observed for all kinds of phosphate monoester resistant starch.     

Physicochemical Characterization and Application of Yam (Dioscorea cayenensis‐rotundata) Starch as a Pharmaceutical Excipient

Yam starch from Dioscorea cayenensis‐rotundata complex was isolated and characterized by scanning electron microscopy (SEM), particle size analysis, X‐ray diffraction, differential scanning calorimetry (DSC), compaction and rheology, and compared to maize (Zea mays) and potato (Solanum tuberosum) starches. Yam starch exhibited a log‐normal distribution of flattened ovoid shaped granules with a mean particle size of 25 µm. X‐ray diffraction showed a C‐type crystalline pattern with the degree of relative crystallinity estimated to be 34%. DSC analysis suggests that the crystalline regions in yam starch are thermally and structurally more stable as in maize and potato. Irrespective of the relative humidity (39, 67, 78% R.H.) yam starch exhibited higher moisture uptakes than maize starch and lower than potato. Intermediate values of swelling power and amylose leaching were obtained for yam as compared to maize and potato. Compaction properties of yam and potato starches were similar. However, compacts from yam presented a relatively lower tensile strength. Aqueous starch systems (4%) of yam and maize starches showed analogous shear‐thinning (pseudo‐plastic) behavior suitably described by the power‐law model. These results support the potential use of yam starch as excipient comparable to potato starch in pharmaceutical solid forms and as thickening agent similar to maize in pharmaceutical applications.     

微波对板栗淀粉结构和理化性质的影响

为探讨微波辐照对板栗淀粉颗粒结构和理化性质的影响,采用微波辐照板栗淀粉,通过扫描电镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、差示扫描量热仪(DSC)等研究微波处理不同时间后板栗淀粉的颗粒结构和理化特性。研究表明:与原淀粉相比,微波处理后板栗淀粉的微观形貌发生明显变化,但淀粉颗粒仍为C型晶体。随着微波处理时间的增加,直链淀粉含量增大,淀粉颗粒表面出现裂纹、孔洞和黏结越显著,淀粉颗粒的相对结晶度降低、红外光谱(1 047/1 022)cm~(-1)峰强度比值降低;淀粉膨胀度和透光率也随微波处理时间的增加而降低。DSC分析表明,微波处理80 s的淀粉相转变温度(T_o和T_p)降低、糊化焓(ΔH)减少。表明微波辐照对板栗淀粉的颗粒结构和理化特征均有显著影响。     

Thermal properties of new varieties of yam starches

Starches isolated from yam varieties of Dioscorea alata and Dioscorea cayenensis‐rotundata species were prepared at different time–temperature conditions and characterised by DSC, amperometric iodine titration, light microscopy and rheology and compared to native and chemical modified tapioca starches. The observation by light microscopy showed different morphologies of the granules when heated above 100°C and the tendency for disintegration decreased in the order native tapioca starch > yam starch > modified tapioca starch. Differences between yam and tapioca starches were also revealed by DSC. Yam starch enthalpy is higher than tapioca starch, but the peak temperature is low. However, the significant differences between yam and the other tested starches were found in terms of their rheological behaviour. The viscosity of yam starch was very stable at high temperatures on the viscograph. With this property, yam starch can be used as thickening and gelling agent in food.     

山药及零余子酸、酶处理淀粉的理化性质

利用酸和淀粉酶、糖化酶分别处理山药及零余子淀粉,利用扫描电镜、X射线衍射及流变仪等测定不同处理组淀粉的理化特性。结果表明：山药和零余子原淀粉颗粒较为完整,没有裂缝,呈卵圆形,表面光滑;酶、酸处理均会导致淀粉降解,酸处理淀粉表面破坏最为严重;零余子原淀粉、酸处理和酶处理的淀粉结晶度分别为32.02%、27.02%和31.13%,而山药原淀粉、酸处理和酶处理淀粉结晶度分别为34.32%、29.27%、33.55%。淀粉糊透光率、凝沉百分比表明零余子原淀粉最易老化,流变特性表明不同处理组的淀粉均具有弱凝胶特性。     

油莎豆抗性淀粉结构特征及体外消化特性研究

以油莎豆淀粉为原料，用压热法、酶法和压热-酶法制备油莎豆抗性淀粉（分别记为A-CRS、E-CRS和AD-CRS），研究其结构特征和体外消化特性。结果表明，油莎豆淀粉颗粒光滑饱满，形状不一，而抗性淀粉的形态发生显著变化，结构不完整，外观粗糙。油莎豆淀粉为A型晶体结构，三种抗性淀粉为C+V型结构。与原淀粉相比，三种抗性淀粉的平均粒径增大，RS含量、结晶度和热稳定性均显著提高，而平均聚合度降低， 其中AD-CRS的结构最紧密，结晶度最高。体外模拟消化显示A-CRS、E-CRS和AD-CRS的消化速率均小于原淀粉，其血糖指数（GI）分别为39.86、39.84、39.83，属于低GI食品(GI＜55)。综上所述，油莎豆抗性淀粉的结构较紧密，具有较强的体外抗消化能力和调控血糖的潜力。     

Physicochemical Properties of Carboxy-methylated Sago (Metroxylon sagu) Starch

ABSTRACT: Carboxymethyl starch (CMS) with degree of substitution (DS) ranging from 0.1 to 0.32 was prepared from sago ( Metroxylon sagu ) starch in non-aqueous medium using isopropanol as a solvent. The physico-chemical, rheological, and thermal properties of the starches were investigated. At room temperature (25 °C), CMS hydrated readily, resulting in higher swelling power compared with native (unmodified) starch. Light microscopy revealed that CMS granules imbibed more water than native starch at room temperature and thus caused a larger increase in granule size. Some of the CMS granules lost their integrity. Scanning electron microscopic observation revealed fine fissures on the surface of CMS (DS 0.32) granules compared with a relatively smooth surface of native starch granules. Carboxymethylated sago starch exhibited excellent dispersibility and cold water solubility as judged by the absence of peak viscosity in the pasting profile (determined by Rapid ViscoAnalyzer). Pasting profile of CMS was qualitatively similar to pregelatinized starch. Despite exhibiting greater swelling power, CMS showed significantly lower pasting viscosity compared with the native starch. Intrinsic viscosity was also greatly reduced by carboxymethylation. Studies using differential scanning calorimetry (DSC) showed that transition temperatures and enthalpies decreased with an increase of degree of substitution. CMS at higher substitution levels (DS 0.27 and 0.32) showed significantly lower retrogradation tendency, as indicated by lower setback, absence of DSC endotherm upon storage at 4 °C and lower syneresis upon repeated freeze-thaw cycles. The results suggested that retrogradation might be effectively retarded by the presence of the bulky carboxymethyl group.     

Physicochemical Properties of Starch Isolated from Bracken (Pteridium aquilinim) Rhizome

Bracken (Pteridium aquilinum) is an important wild plant starch resource worldwide. In this work, starch was separated from bracken rhizome, and the physicochemical properties of this starch were systematically investigated and compared with 2 other common starches, that is, starches from waxy maize and potato. There were significant differences in shape, birefringence patterns, size distribution, and amylose content between bracken and the 2 other starches. X‐ray diffraction analysis revealed that bracken starch exhibited a typical C‐type crystalline structure. Bracken starch presented, respectively, lower and higher relative degree of crystallinity than waxy maize and potato starches. Ordered structures in particle surface differed among these 3 starches. The swelling power tendency of bracken starch in different temperature intervals was very similar to that of potato starch. The viscosity parameters during gelatinization were the lowest in waxy maize, followed by bracken and potato starches. The contents of 3 nutritional components, that is, rapidly digestible, slowly digestible, and resistant starches in native, gelatinized, and retrograded starch from bracken rhizome presented more similarities with potato starch than waxy maize starch. These finding indicated that physicochemical properties of bracken starch showed more similarities with potato starch than waxy maize starch.