Physicochemical properties and in vitro digestibility of resistant starch from mung bean (Phaseolus radiatus) starch

RS from mung bean starch was prepared by autoclaving, pullulanase debranching, and retrogradation. Physicochemical properties, crystalline structure, and in vitro digestibility of selected RS samples with different RS content were investigated. Compared to native starch, AAM content of RS increased but MW decreased greatly. SEM clearly showed RS samples exhibited irregular shaped fragments with compact structure. XRD pattern indicated that RS samples had typical B‐type pattern with sharp peaks at 17.0°, 22.2°, and 23.9° 2θ. The relative crystallinity, gelatinization temperatures, and enthalpy increased with increasing RS content. The α‐amylase digestibility of RS was lower than that of native starch. The results suggested that the decrease in enzymatic digestion of RS might due to compact and ordered crystalline structures after debranching and recrystallization.     

The effect of annealing on resistant starch content of different crop types: a systematic review and meta-analysis study

The growing demand for functional foods with a high resistant starch content (per cent RS) could be met by annealing starch modification. Through a meta-analysis, this study sought to shed light on the effect of annealing on the resistant starch content of various crop types. Twenty-one studies published between 2000 and 2020 were selected and eighty data points were extracted to be analysed using meta-essential tools. Hedge’s d Standardised Mean Difference (SMD) was designated for the effect size approach. Resistant starch content was influenced by the botanical origin of the carbohydrate source and the annealing parameters such as moisture content, incubation time and temperature. According to a meta-analysis of the data collected, the most significant increase in per cent RS is perceived on cereal (SMD: 7.58; 95% CI: 2.88–12.29; P = 0.001). Further analysis revealed that normal wheat had the highest significant per cent RS increase (SMD: 41.56; 95% CI: 19.52–63.61; P = 0.001). Annealing parameters resulted in significant %RS increase were moisture content of 80%, incubation time of 24 h and incubation temperature of 50–54 °C. These results were expected to provide data to optimise per cent RS increase through annealing efficiently.     

Structural and physicochemical characterization of RS prepared using hydrolysis and heat treatments of chickpea starch

The aim of this study was to evaluate the production and the structural and physicochemical properties of RS obtained by molecular mass reduction (enzyme or acid) and hydrothermal treatment of chickpea starch. Native and gelatinized starch were submitted to acid (2 M HCl for 2.5 h) or enzymatic hydrolysis (pullulanase, 40 U/g per 10 h), autoclaved (121°C/30 min), stored under refrigeration (4°C/24 h), and lyophilized. The hydrolysis of starch increased the RS content from 16% to values between 20 and 32%, and the enzymatic treatment of the gelatinized starch was the most efficient. RS showed an increase in water absorption and water solubility indexes due to hydrolytic and thermal process. The processes for obtaining RS changed the crystallinity pattern from C to B. Hydrolysis treatments caused an increase in relative crystallinity due to the greater retrogradation caused by the reduction in MW. RS obtained from hydrolysis showed a reduction in viscosity, indicating the rupture of molecules. The viscosity seemed to be inversely proportional to the RS content in the sample.     

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.     

韧化处理对3种晶型淀粉消化特性的影响

比较玉米淀粉(A型)、马铃薯淀粉(B型)和锥栗淀粉(C型)韧化处理前后的颗粒形貌、结晶特性和热特性变化,探究韧化处理对3种晶型淀粉消化特性的作用机理。SEM图片显示,韧化处理后玉米淀粉表面出现凹坑,马铃薯淀粉表面出现少许裂痕,锥栗淀粉表面变得光滑,褶皱消失;XRD和FTIR分析表明,3种淀粉经韧化后晶型未有改变,但结晶度均显著提高,分子短程有序性增加,晶体结构更趋稳定;DSC分析表明,韧化处理后3种晶型淀粉的糊化温度显著升高,热焓值无显著变化;韧化处理对不同晶型淀粉消化特性的影响存在差异,3种淀粉经韧化后RS含量均显著增加,水解指数HI和血糖指数GI显著降低;玉米淀粉韧化后RDS含量显著增加,SDS含量显著减少,水解平衡浓度由84.81%降至76.79%;马铃薯淀粉中SDS和RDS含量均显著减少,水解平衡浓度由30.59%降至21.84%;韧化处理对锥栗淀粉的RS、SDS、RDS含量及水解平衡浓度变化影响较小。     

Effects of Annealing on ultra-high pressure induced gelatinization of corn starch

Ultra-high pressure (UHP) can induce starch gelatinization at the room temperature, while the change of starch architecture could affect the gelatinization process. This work evaluated the effects of annealing on UHP induced starch gelatinization. Native and annealed corn starches were subjected to UHP treatment (300–600 MPa) for 15 min at room temperature. The scanning electron microscopy, confocal laser scanning microscopy, differential scanning calorimetry and X-ray diffraction analysis showed that UHP treatment partially disrupted the ordered structures of native and annealed starches, which made starch gelatinized gradually and a transformation in crystal type from type A to type B. However, compared with native starch, annealing (C3 and C24) delayed the internal and external structure destruction of starch granules, as well as induced a slower decrease in ΔH and relative crystallinity as increasing pressure. Therefore, the suitable UHP treatment can increase the pressure resistance of starch, or delay the UHP gelatinization process.     

Characterisation of low‐digestible starch fractions isolated from amylosucrase‐modified waxy corn starch

Amylosucrase (AS) modification of starch increases the slowly digestible (SDS) and resistant starch (RS) fractions. However, the characteristics and formation mechanism of each fraction of AS‐modified starch have not been determined yet. Therefore, this study isolated SDS and/or RS from AS‐modified waxy corn starches and investigated their structural characteristics. The amount of SDS+RS and RS had a positive correlation with the proportion of the medium length (13–24 of degree of polymerisation) branched chains of amylopectin. The relative crystallinity increased in the order of AS‐modified starch < SDS+RS < RS, while maintaining the B‐type crystalline structure. The thermal transition temperature ranges of the isolated fractions were also higher than those of undigested starches. The medium branched chains of amylopectin were presumably the clincher for the SDS and/or RS formation in AS‐modified starches. The principal causes of SDS and RS formation were the chain length elongation and the subsequent retrogradation‐like process, respectively.     

Effect of heat-moisture treatment on the formation and physicochemical properties of resistant starch from mung bean (Phaseolus radiatus) starch

Mung bean starch was subjected to a range of heat-moisture treatments (HMT) based on different moisture contents (15%, 20%, 25%, 30%, and 35%) all heated at 120 °C for 12 h. The impact on the yields of resistant starch (RS), and the microstructure, physicochemical and functional properties of RS was investigated. Compared to raw starch, the RS content of HMT starch increased significantly, with the starch treated at 20% moisture having the highest RS content. After HMT, birefringence remained at the periphery of the granules and was absent at the center of some granules. The shape and integrity of HMT starch granules did not change but concavity was observed under scanning electronic microscopy. Apparent amylose contents of HMT starch increased and the HMT starch was dominated by high molecular weight fraction. Both the native and HMT starches showed A-type X-ray diffraction pattern. Relative crystallinity increased after HMT. The gelatinization temperatures (To, Tp, and Tc), gelatinization temperature range (Tc–To) and enthalpies of gelatinization (ΔH) increased significantly in HMT starch compared to native starch. The solubility increased but swelling power decreased in HMT starches. This study clearly shows that the HMT exhibited thermal stability and resistance to enzymatic hydrolysis owing to stronger interactions of starch chains in granule.     

Determining the effects of annealing time on the glass transition temperature of Pueraria lobata (Willd.) Ohwi starch

To probe the effects of annealing time on the glass transition temperature (T_g) and digestibility of Pueraria lobata (Willd.) Ohwi starch, the starch crystal structure and moisture distribution through the components of P. lobata (Willd.) Ohwi starch were investigated. Annealing times of 0, 1, 3, 6, 12 and 24 h were employed to determine the effect of starch T_g using differential scanning calorimetry (DSC) with the support of ¹H low‐field NMR, polarised light microscopy and ¹³C CP/MAS NMR. The T_g values of the starch increased with longer annealing times. The ¹H low‐field NMR results showed that the T₂ relaxation time decreased and starch–water interactions increased as the annealing time increased. Compared with native starch, annealed starch had higher contents of slowly digested starch (SDS) and resistant starch (RS). The starch crystal structure was not destroyed after annealing, but the relative crystallinity percentage increased slightly.     

Effects of organic acids and starch water ratios on the properties of retrograded maize starches

The effects of organic acid types and concentrations as well as starch water ratios on resistant starch (RS) levels and the properties of retrograded maize starches were studied. The pH of the starch slurry decreased with increasing water ratio and organic acid concentration, but the addition of succinic acid slightly reduced pH compared to the other organic acids. The RS level of RS3 was increased 160–169% for the high starch ratio and was increased 137–146% for the low starch ratio with organic acid addition (p<0.01). The color difference between the RS3 powder added with citric acid and native starch showed the lowest value. All samples had B type crystallinity. Their swelling power and solubility increased, but the water binding capacity decreased with organic acid addition. The added organic acids rapidly decreased the pasting viscosity of RS3, but patterns were different by organic acid type (succinic acid) and starch water ratio.     

Improving gel formation of rice starch added with cross‐linked resistant starch prepared from rice starch

The gel formation properties of non‐waxy rice starch with cross‐linked resistant starch with phosphate (RS4, 10, 20, and 30% based on rice starch) prepared from three rice varieties with different amylose (AM) content were investigated to increase dietary fiber content, improve gel structure, and reduce the glycemic index of rice products. The AM contents of rice starches were 1.71% in Hanganchal1, 22.47% in Nampyeong, and 33.39% in Goamy. All RS4 showed A‐type crystallinity and their RS levels were 46.91, 54.54, and 66.01%, respectively. The initial pasting temperatures of RS4 added rice starches increased as RS4 contents increased, but peak and breakdown viscosities and enthalpy change (△H) reduced. The RS4 addition improved gel shape and texture properties including hardness, cohesiveness, and gumminess, except the 30% Goamy RS4 added gel. The 20% RS4 addition was appropriate to form rice starch gels. The network structure of RS4 added gel formed more regular and firmer than that of control, because RS4 granules were entrapped within the gel matrix like observed by light microscope and scanning electron microscopy. It is suggested that RS4 not only assist in forming a rigid network structure but also increasing a dietary fiber content.

     

紫薯淀粉结构与理化性质研究

目的 了解紫薯淀粉的结构和理化性质。方法 利用碱提取法从紫薯中提取淀粉, 与普通玉米淀粉进行对比, 分别对淀粉结构(分子链结构、结晶结构等)和理化性质(透明度、凝沉性、冻融稳定性、热稳定性)进行研究。结果 紫薯淀粉直链含量(24.5%)比玉米淀粉(26.7%)低, 两者均为A型结晶结构, 但紫薯淀粉的结晶度和分子有序程度比玉米淀粉高; 紫薯淀粉糊的透明度高于玉米淀粉糊, 且随时间延长其透明度下降程度比玉米淀粉糊低; 紫薯淀粉糊不易发生凝沉现象, 但其析水率(21.4%)比玉米淀粉糊高, 即冻融稳定性弱于玉米淀粉糊; 此外, 紫薯淀粉部分结构的热稳定性大于玉米淀粉。结论 紫薯淀粉在分子链结构和结晶结构上与玉米淀粉有较小差异, 但在理化性质上与玉米淀粉差别较大, 可为其工业应用提供指导基础。     

Study on the physicochemical properties and in vitro digestibility of starch from yam with different drying methods

Four methods were applied to dry yam slices, and then, starches were isolated from dried yam slices. Starch isolated from fresh yam was as the study control, and physicochemical properties and in vitro digestibility of starches were studied. The results showed that the amylose content ranged from 12.62% to 28.25%, water‐binding capacity (WBC) from 111.67% to 262.88%, paste clarity from 2.1% to 6.23%, resistant starch (RS) from 66.60% to 88.49% and crystallinity from 11.27% to 25.52%. Compared with the control starch, hot air‐drying at 60 °C significantly decreased amylose content, paste clarity, RS and crystallinity, while increasing the WBC. Low levels of rapidly digestible starch and glucose and high RS levels were found in the starch from freeze‐drying yam. Digestibility of the starches was significantly correlated with amylose content, WBC, paste clarity and swelling power. The starch samples were divided into three groups by principal component analysis (PCA).     

Effects of gamma irradiation on starch digestibility of rice with different resistant starch content

Three rice cultivars (RS3M, RS4H and RS5L) differing in resistant starch contents but similar in genetic background were chosen to study the effects of gamma irradiation on starch physicochemical properties and digestibility. Irradiation increases the resistant starch content in all the three cultivars and in a dose‐dependent manner in rice with low‐resistant starch content (RS5L). Irradiation decreases apparent amylose content and gelatinisation temperature and changed the starch granule structure, while increasing V‐type crystallinity. Starch enzymatic hydrolysis rate was reduced following irradiation, and the effect of irradiation on reducing starch digestibility was negatively correlated with resistant starch content. Treatment with gamma irradiation has therefore a potential for increasing resistant starch content and producing low digestibility of starch in common rice.     

Effect of repeated freezing-thawing on structural,physicochemical and digestible properties of normal and waxy starch gels

The normal and waxy corn starch gels were subjected to repeated freeze–thaw treatment at 0, 1, 2, 3, 4,5 and 6 cycles with an interval of 24 h, and the effects on structural, physicochemical and digestible properties were investigated. The normal starch gels formed a honeycomb structure while waxy starch gels exhibited a lamellar structure, and the number of holes and lamellas increased with increasing cycles. The X-ray analysis showed that the A-type pattern of starches was converted into the B-type after treatment, and their relative crystallinity increased with the number of increased freeze–thaw cycles. The hardness increased in both normal and waxy starch. The solubility and pasting breakdown viscosity decreased in normal starch while they increased in waxy starch. The pasting peak time, peak viscosity, and setback viscosity increased in normal starch but decreased in waxy starch. The rapidly digested starch (RDS) and slowly digested starch (SDS) content in normal starch increased and non-digestible starch (RS) content decreased whereas the RDS, SDS and RS content in waxy starch was almost unchanged as the freeze–thaw cycles increased. In the meantime, the molecular weight of both normal and waxy starch decreased with freeze–thaw treatment. Therefore, the repeated freeze–thaw treatment can change the physicochemical and digestible properties which could be a basis for starch-based food processing.     

Effect of lysine incorporation,annealing and heat moisture treatment alone and in combination on the physico-chemical,retrogradation, rheological properties and in vitro digestibility of kithul (Caryota urens L.) starch

Physico-chemical, retrogradation, rheological properties and in vitro digestibility of lysine incorporated kithul starch modified by annealing, heat moisture treatment and its combinations were studied. LS-AHMT (annealed-heat moisture treated lysine incorporated kithul starch) exhibited lowest amylose leaching. LS-AHMT showed significantly (P ≤ 0.05) higher relative crystallinity. LS-ANS (annealed lysine incorporated kithul starch), LS-HMT (heat moisture treated lysine incorporated kithul starch) and LS-AHMT formed more weak gel by the effect of annealing, heat moisture treatment and its combination. LS-AHMT showed lowest pasting viscosities, G′ and G″ values among the modified kithul starch, which indicates its lower retrogradation properties. In vitro digestibility of kithul starch decreased after modifications and LS-ANS, LS-HMT and LS-AHMT showed significantly higher resistant starch content. The current study showed that annealing, heat moisture treatment and its combination on NS-LS (lysine incorporated kithul starch) effectively modified kithul starch properties.     

Resistant starch modification: effects on starch properties and functionality as co-encapsulant in sodium caseinate-based fish oil microcapsules

The properties of resistant starch (RS) modified by heating starch suspensions (Heat RS) or heating followed by microfluidization (Heat-MF RS) and their functionality as co-encapsulants in sodium caseinate (NaCas) based fish oil microcapsules (50%oil:25%NaCas:25%starch) were examined. RS modification reduced molecular weight and crystallinity of the starch, with the effects being more evident for Heat-MF RS. The properties of fish oil microcapsules were influenced by the starch type used (RS, Heat RS, or Heat-MF RS) in combination with NaCas. With both physical blends and heated mixtures of NaCas and starch as encapsulants, highest encapsulation efficiency but lowest oxidative stability was obtained for the microcapsules containing Heat-MF RS. Oxidative stability was independent of heat treatment applied to the mixtures of NaCas and starch and also not related to encapsulation efficiency of the freeze-dried microcapsules. The properties of the starch used in combination with NaCas were the major determinant of the oxidative stability, with lower molecular weight and decreased crystallinity providing less protection against oxidation.     

微波对玉米淀粉结构及理化性质的影响

本实验采用微波（累积能量值为1 680 J/g）处理不同的淀粉-水体系,观察淀粉颗粒形态的变化,并测定透明度、沉降物体积、吸水率、持水性、相对结晶度和流变特性等指标。结果表明,随着淀粉-水体系中水分质量分数的增加,淀粉颗粒的完整性和偏光十字逐渐减弱;与玉米淀粉相比,微波处理淀粉乳透明度、沉降物体积、吸水率和持水性明显增加;X射线衍射图谱表明微波处理后淀粉颗粒仍为A型而相对结晶度下降,说明微波处理破坏了淀粉的结晶结构;微波处理没有改变淀粉乳流体的类型,弹性模量均大于黏性模量,表明均以弹性性质为主。结论：微波处理淀粉-水体系对淀粉的颗粒结构和理化特征均有显著影响,本研究结果可为开发具有独特理化性质的改性淀粉或改进淀粉改性工艺提供实验与理论依据。     

Synthesis and in vitro digestion of resistant starch type III from enzymatically hydrolysed cassava starch

Resistant starch type III (RS III) was synthesised from cassava starch by autoclaving followed by debranching with pullulanase, at varied concentrations (0.4–12 U g^?1) and times (2–8 h), and recrystallisation (?18 to 90 °C for 1–16 h). The highest RS III yield (22 g/100 g) was obtained at an enzyme concentration of 4 U g^?1 after 8 h incubation, followed by recrystallisation at 25 °C for 16 h. Varying the recrystallisation conditions indicated that higher RS III yields (30–35 g/100 g) could be obtained at 90 °C within 2 h. Thinning cassava starch using α‐amylase prior to debranching using pullulanase did not further increase the RS III content. In vitro digestion data showed that whereas 44% RS III was digested after 6 h, the corresponding value for cassava starch was 89%.     

等离子体活化水韧化处理对蜡质玉米淀粉和玉米淀粉结构及性能的影响

本文研究了等离子体活化水（plasma-activated water,PAW）协同韧化处理对蜡质玉米淀粉（waxy maize starch,WMS）和玉米淀粉（maize starch,MS）结构及性能的影响。结果表明,与常规韧化处理相比,PAW韧化没有改变WMS和MS的结晶类型,但降低了相对结晶度。WMS的相对结晶度从37.1%降低到25.9%,MS的相对结晶度从30.3%降低到27.7%。PAW韧化没有使淀粉分子产生新的官能团,但导致WMS和MS的短程有序性降低。PAW韧化降低了WMS和MS的糊化焓（WMS:13.33~12.10 J/g、MS:10.76~10.26 J/g）、峰值黏度和黏弹性,提高了淀粉糊的凝胶强度。PAW协同韧化处理提供了一种淀粉双重物理改性的新方法,在淀粉基凝胶领域具有潜在的应用。