Effect of phosphoric acid treatment on physicochemical,functional, and structural properties of starch extracted from yam (Dioscorea rotundata)

This work was designed to elucidate selected physicochemical, functional, and structural properties of native and modified yam (Dioscorea rotundata) starch. The isolated starch was chemically modified using 5, 10, 15, 20, and 25% phosphoric acid solution at 50°C for 1 h, and yield, swelling power, gelation, water holding capacity, paste clarity, blue value, and amylose and amylopectin content of the native and modified yam starch were determined. Structural changes in the native and starch modified with 25% phosphoric acid were evaluated using Fourier transform infrared spectroscopy and optical microscopy. The result showed that the yield, swelling power, water holding capacity, paste clarity, blue value and amylose and amylopectin content of native yam starch was 33.38% (217 g), 3.84 g/g, 1.0 v/g, 10%, 0.52 and 25.96, respectively, whereas gelation study of the native and modified starch indicated that native starch was viscous and modified starch firm. However, yield, swelling power, water holding capacity, paste clarity, blue value, and amylose content of modified yam starch reduced in a dose dependent manner with phosphoric acid. The reduction in the values of the various functional properties could be associated with the effect of phosphoric acid on the starch granular structure. The result of Fourier transform infrared spectroscopy and optical microscopy revealed that the yam starch was modified by phosphoric acid with changes in functional groups spectra such as –OH stretch (3177 cm^?1), H₂O absorbed (1644 cm^?1) (amorphous region), C-H stretch (2923 cm^?1), CH₂O (1253 cm^?1), and C-O-C (1078 cm^?1) when compared to native starch. The morphology of native and modified yam starch granules ranged from oval to eliptical. However, modified starch granules were rough in surface. In conclusion, the characterized physicochemical and functional properties and structure exhibited by native and modified yam starch indicated that, yam could be a cheap and valuable source of starch for industrial application.     

Preparation, physicochemical characterization and in vitro digestibility on solid complex of maize starches with quercetin

The objective of this study was to prepare and characterize solid complex of starch with quercetin. Starches with different content of quercetin were prepared and their formation was confirmed by the presence of the carbonyl signal around 1662 cm⁻¹ in the FT-IR spectra. Scanning electron microscopy (SEM) suggested most of the starch granules disintegrated with many visible fragments along with increasing quercetin content in the binary mixtures. X-ray diffraction (XRD) of quercetin-starch complexes revealed that the crystal structure of native starch was disappeared and new crystalline regions were formed. The thermal behavior of quercetin-starch was investigated using thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC). It was observed that the mass loss and thermal stability of complexes depend on the content of quercetin in the complexes. There were obvious differences between pregelatinized starch and quercetin-starch complexes in digestion rate. The digestion rate was drastically reduced as the quercetin was blended. The digestion rate was steady at about 37.3% for pregelatinized starch and 10.1% for quercetin-starch complex (2.5 g/100 g) after incubating 2 h. The residual starch of quercetin-starch complexes can be thought as resistant starch, the amounts of resistant starch were sharply increased in comparison with the pregelatinized starch.     

Amylose content,molecular structure,physicochemical properties and in vitro digestibility of starches from different mung bean (Vigna radiata L.) cultivars

Physicochemical and in vitro digestibility characteristics of starches isolated from six cultivars of mung bean (Vigna radiata L.) were studied. Significant differences (p < 0.05) were observed between the cultivars with respect to amylose content (29.9–33.6%), relative crystallinity (29.0 to 31.7%), particle diameter (16.2–17.1 µm) and molecular weight of amylopectin (260–289 × 10⁶ g/mol). The scanning electron micrographs revealed the presence of large oval to small round shape granules with average particle diameter of 16.2–17.1 µm. The X‐ray diffraction pattern was of the C‐type. The enthalpies of gelatinization and retrogradation were 8.9–10.3 and 4.6–6.3 J/g, respectively. The amounts of slowly digesting and resistant starch of mung bean followed the order: PBM‐1 > SML‐32 > ML‐613 > SML‐134 > ML‐267 > ML‐5 and ML‐5 > ML‐267 > SML‐134 > ML‐613 > SML‐32 > PBM‐1, respectively. The six starches exhibited significant (p < 0.05) differences in their pasting parameters. Correlation analysis showed that amylose content, granule diameter and relative crystallinity values were important in determining thermal, pasting and in vitro digestibility of starches.     

Structure,functionality, and digestibility of acetylated hulless barley starch

Hulless barley starch was extracted and further acetylated using acetic anhydride at different level (3.75, 7.5, 11.25 g/100 g) in this study. The structure changes and functional properties of acetylated hulless barley starches comparing to the native starch were evaluated and analyzed. The shape of granules remained unaltered with cracks formed after modification. Small- (1 μm) and large-sized (20 μm) were observed in four kinds of starches while granule particle sizes distribution changed dramatically. Four hulless barley starches presented A-type x-ray diffraction pattern, with relative crystallinity of 25.6, 27.1, 26.2, and 24.8% for native and acetylated starches. The infrared ratio of 1045/1024 and 1025/995 cm^?1, indicated the difference in long-range order of crystallinities and short-range order of double helices. Results observed in swelling power, gelatinization parameters, pasting viscosities, and in vitro digestibility indicated acetylated hulless barley starch’s potential as a functional food additive and a healthy ingredient.     

马铃薯抗性淀粉结构特征及体外消化特性的研究

研究马铃薯抗性淀粉的结构特征与体外消化特性。方法 以马铃薯淀粉为对照, 采用红外光谱仪、XRD、DSC等手段研究了马铃薯抗性淀粉的碘吸收特性、颗粒形貌、晶型结构形态、热特性等。通过模拟体外消化评价了抗性淀粉的消化性能。结果 马铃薯淀粉和抗性淀粉碘吸收曲线最大吸收峰在580~600 nm,马铃薯抗性淀粉分子量分布更集中。马铃薯淀粉为B型结晶结构, 马铃薯抗性淀粉为C型结晶结构。SEM观察显示：马铃薯淀粉分子颗粒完整, 表面光滑, 整体呈不规则的椭圆形; 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; 红外光谱分析表明抗性淀粉未出现新的基团。DSC检测发现：马铃薯抗性淀粉的热稳定性更高; 马铃薯淀粉和抗性淀粉酶解前2 h内消化速率迅速增加, 酶解2 h后速率减慢, 消化速率逐渐趋于平缓, 血糖指数分别为70.42、40.50。结论 说明马铃薯抗性淀粉具有较致密的结晶结构和酶抗性, 抗消化性显著。     

Physicochemical,rheological, morphological,and in vitro digestibility properties of cross-linked starch from pearl millet cultivars

The effect of epichlorohydrin (0.5%) as a cross-linking agent on physicochemical, rheological, morphological, and in vitro digestion properties of pearl millet starches from different cultivars was studied. Degree of cross-linking (DC) ranged between 40.61% and 89.75%, lower values of DC were observed for cv.HC-10 and cv.HHB-67 whereas higher values were observed for cv.HHB-223 and cv.GHB-732. Cross-linked starch from cv.GHB-732 showed the lowest amylose content, swelling power, and solubility as compared to other cultivars. Rheological properties of starches during heating showed their elastic behaviour. G′ value was much higher than the G′′ value at all frequency values for starch pastes. Plots of shear stress (σ) versus shear rate (γ?) data for cross-linked starch pastes were fitted to Herschel-Bulkley model and yield stress (σ_o), flow behaviour index (n), and consistency index (K) were evaluated. Scanning electron micrographs (SEM) investigations revealed that cross-linked starch granules had slightly rough surfaceand grooves with slight fragmentations. Readily digestible starch (RDS) of cross-linked starches varied from 46.1% to 50.6%, cv.GHB-732 had the lowest value. Slowly digestible starch (SDS) and resistant starch (RS) content of cross-linked starches ranged from 34.5% to 36.4% and 13.6% to 19.4%, respectively. cv.HC-10 had the highest value for SDS content while the highest RS content was observed for cv.GHB-732. In comparison to native starches, cross-linked modification decreased SDS and RDS content whereas RS content was increased.     

木薯淀粉与胶原蛋白作物物理化及其体外消化性质研究

研究了蛋白一淀粉作用物的粘度曲线特征,溶胀能力等理化性质,采用改进的In—Vitro体外消化模型模拟人体消化道环境,对不同蛋白质含量的蛋白一淀粉作用物样品的消化性能进行了研究。研究表明,该作用物不易糊化．其糊的粘度显著低于原淀粉,溶胀能力降低;由于胶原蛋白与木薯淀粉的相互作用,底物结构发生改变,使得作用物的消化性能随着蛋白质含量的增加而降低。     

Turmeric powder and starch: selected physical, physicochemical, and microstructural properties

Turmeric powder and its starch were characterized for physical, physicochemical, and microstructural characteristics. X-ray diffractogram indicated that turmeric starch to be of B type. Dried and cured-dried turmeric powder samples showed higher water-holding capacity (3.62 and 4.78 g/g, respectively) compared to isolated starch (1.07 g/g) at 30 °C. Non-Newtonian shear-thinning characteristics were observed with turmeric powder dispersion containing 10% (w/w) solids. A power law model fitted well to correlate the shear-rate and shear-stress data (r= 0.993 to 0.999, P≤ 0.01) for both samples. Apparent viscosities of isolated turmeric starch and cured-dried turmeric powder dispersion containing 10% (w/w) solids were 1.29 ± 0.03 and 7.57 ± 0.39 mPa s, respectively. Microstructure of starch particles showed a smooth flat outer surface. The approximate length and breadth of isolated elliptical starches were 25 and 10 μm while the thickness was about 5 μm. PRACTICAL APPLICATION: Isolation and characterization of starch from an unconventional source like turmeric rhizome indicate a potential application as a functional ingredient in foods and pharmaceutical industries including agglomerated products.     

The effect of thermal processing and storage on the physicochemical properties and in vitro digestibility of potatoes

Shepody potatoes were cooked using three common cooking methods – microwaving, boiling and pressure cooking. Microwaving for 2.5 min retained the highest amounts of slowly digestible starch (SDS, 19.6%) and resistant starch (RS, 48.8%) as compared to the other cooking treatments. Similarly, enthalpy and FTIR results (ratio of 1047/1022 cm^?1) were also higher for microwaved samples, again indicating incomplete gelatinisation. Potatoes were also boiled for 15, 30 or 45 min, followed by 1, 3 or 7 days retrogradation at 23 or 4 °C. Retrogradation enthalpy increased significantly (P ≤ 0.05) with increased storage time and decreased storage temperature; FTIR results displayed temperature dependency; at 4 °C, ordered structure increased with increasing storage time, whereas the opposite trend was seen at 23 °C. Lastly, formation of SDS and RS was favoured for longer boiling times (30 – 45 min), extended storage times (3–7 days) and 4 °C.     

环氧氯丙烷交联淀粉的制备及其体外消化性能的研究

以环氧氯丙烷为交联剂,制备土豆交联淀粉。用正交实验考察环氧氯丙烷用量、氢氧化钠用量、反应温度和反应时间四个因素对交联度的影响,确定最佳工艺条件,并对体外消化条件进行优化,对不同交联度淀粉的消化速度进行研究。体外淀粉消化条件的优化实验显示,消化产物测定的最佳条件为：波长485nm,显色温度100℃,显色时间30min,葡萄糖浓度范围0～80μg/mL,其回归方程为y=0.0044x-0.005,R2=0.9988,且样品溶液在2h内显色稳定。各因素对交联淀粉制备影响的重要性依次为环氧氯丙烷用量、氢氧化钠用量、温度及反应时间;最佳工艺条件为：以50g土豆淀粉计,环氧氯丙烷用量为1.00mL,氢氧化钠用量为0.75g,温度50℃,时间6h,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。     

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。     

疣柄魔芋淀粉理化及功能性质研究

为了探索一种新的淀粉资源,对疣柄魔芋淀粉的性质进行了研究。通过电子显微镜、激光粒度分析、X-衍射分析、红外光谱分析等分析手段,并以玉米淀粉和木薯淀粉进为比较,结果显示:疣柄魔芋淀粉淀粉颗粒呈多面体形,棱角较尖锐突出;其粒径小于木薯淀粉和玉米淀粉;结晶型为A-型,相对结晶度为37.4%;红外光谱吸收峰、吸收强度与木薯淀粉和玉米淀粉基本相同;凝胶强度、糊化起始温度和糊化热焓高于木薯淀粉和玉米淀粉;且其抗酶解性优于木薯淀粉和玉米淀粉。因此,疣柄魔芋淀粉是一种潜在的可被开发为抗性淀粉的新资源淀粉。     

Effects of pulsed electric fields (PEF) treatment on physicochemical properties of potato starch

Potato starch–water suspensions (8.0%, w/w) were subjected to pulsed electric fields (PEF) treatment at 30 kV·cm^− 1, 40 kV·cm^− 1 and 50 kV·cm^− 1, respectively. The physicochemical properties of PEF-treated potato starch samples were investigated using scanning electron microscopy (SEM), laser scattering technique, X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and the Brabender rheological method, with native potato starch as reference. It has been concluded from SEM analysis that dissociation and damage of PEF-treated potato starch granules appeared. Some granules aggregated with each other and showed gel-like structures. It was revealed from particle size analysis that there was an obvious increase of the granule size after PEF treatment. This has been attributed to the aggregation among granules. It was also demonstrated from other analysis that relative crystallinity, gelatinization temperatures, gelatinization enthalpy, peak viscosity as well as breakdown viscosity of modified samples all decreased with increasing electric field strength.

Industrial relevance

In this study, the effect of PEF treatment (up to 50 kV·cm^− 1) on physicochemical properties of potato starch has been investigated. The results from SEM images showed that dissociation, denaturation and damage of potato starch granules had been induced by the PEF treatments. Some of granule fragments showed gel-like structures, and congregated with each other or with other starch granules. Laser scattering measurements of particle size revealed that an obvious increase of granule size under electric field strength of 50 kV·cm^− 1, which was attributed to the aggregation of the starch granules. The X-ray diffraction pattern showed an obvious loss of crystalline structure after the PEF treatment at 50 kV·cm^− 1, which induced a trend of transformation from crystal to non-crystal in potato starch granules. DSC analysis showed a decrease in gelatinization temperatures (T_o and T_p) and gelatinization enthalpy (ΔH_gel) with increasing electric field strength. Brabender rheological method has been used to show that the peak viscosity and breakdown viscosity decrease with increasing electric field strength of PEF treatment. All the results reveal that the PEF treatment can lead to an intragranular molecular rearrangement of potato starch granules, which induces changes of various physicochemical properties of the treated starch thus may endow it some new characteristics and functions. This phenomena may warrant further more detailed study.     

Effects of different cooking methods on chemical compositions,in vitro starch digestibility and antioxidant activity of taro (Colocasia esculenta) corms

The impacts of different cooking methods (boiling, steaming, baking, microwaving and frying) on chemical compositions, starch digestibility and antioxidant activity of taro corms were investigated. Compared with raw taro, boiling and frying reduced crude protein and ash contents. Frying significantly increased crude fat and fibre contents but decreased carbohydrate content. All cooking methods reduced oxalate content, especially frying. Among the cooked products, the boiled taro had the highest rapidly digestible starch (RDS) but the lowest resistant starch (RS) contents. In contrast, the fried taro provided the lowest RDS but the highest RS contents. All cooking methods reduced the total phenolic content and antioxidant activity of taro. The boiled taro had the lowest antioxidant activity but the fired taro provided the highest. Frying was able to retain most of the health-promoting compounds with the lowest oxalate content; however, the high consumption of high-fat fried taro may adversely affect human health.     

条斑紫菜可溶性膳食纤维的理化性质及体外生物活性研究

目的 采用超声辅助酶法提取条斑紫菜中的可溶性膳食纤维(Soluble dietary fiber, SDF),分析其理化性质及体外生物活性,并对其结构进行表征。方法 以条斑紫菜SDF为研究对象,测定多糖/糖醛酸/硫酸基含量、持水力/持油力/膨胀力、胆酸钠/胆固醇吸附力等指标。采用体外酶抑制实验测定条斑紫菜SDF对α-淀粉酶、α-葡萄糖苷酶和胰脂肪酶的抑制效果。通过扫描电镜、傅里叶变换红外光谱分析、X射线衍射分析条斑紫菜SDF的表观结构。结果 采用超声辅助酶法制备得到的SDF得率为16.12±0.04%,表明超声辅助可有效缩短提取时间、提高提取率。条斑紫菜SDF的多糖、糖醛酸、硫酸基含量分别为30.16%±2.67%、3.29%±0.04%、29.57%±1.25%。条斑紫菜SDF具备良好的持水性、持油力、膨胀力,且对胆固醇和胆酸钠均有一定的吸附能力。在0.2~1.0 mg/mL范围内,条斑紫菜SDF对α-淀粉酶和α-葡萄糖苷酶的抑制作用呈剂量依赖性,当质量浓度为1.0 mg/mL时,抑制率分别为50.76%±3.04%、45.02%±2.54%。在条斑紫菜SDF质量浓度为9 mg/mL时,对胰脂肪酶抑制率达到77.41%±1.21%。条斑紫菜SDF表面呈蜂窝状结构,具有典型的多糖特征峰,结晶度较低。结论 条斑紫菜SDF具有良好的理化特性,体外生物活性强,可作为开发辅助降糖降脂产品的原料。