In vitro digestibility,pasting, and structural properties of starches from different cereals

Starches isolated from seven different cereals were evaluated for their composition, physicochemical, in vitro digestibility, structural, morphological, and pasting properties. The in vitro starch digestion rate and estimated glycemic index (GI) of cereal starches were evaluated along with the impact of cooking on starch digestion. The cooking of starch slurries increased the rapidly digestible starch content from a range of 34.7–54.4% to a range of 60.5–78.5%. On the basis of hydrolysis index, the GI ranged from 83.6 to 91.8 and after cooking it increased from 95.1 to 98.6 for different cereal starches. Both the swelling power and solubility showed an increasing trend with rising temperature. Paste clarity of starches negatively correlated with fat content. The amylose content of various starches ranged from 17.7 to 24.7% and was negatively correlated to crystalline index (r = -0.975, p ≤ 0.05). XRD pattern revealed A-type pattern of crystalline starch, where crystallinity index ranging between 28.2 to 44.9%. FTIR revealed slight differences among chemical bonding of starches from different cereals. From scanning electron micrograph observations, wheat and barley starch granules proved smoother as compared to other cereal granules. Barley contained the highest (27.5 µm) and rice had the lowest (10.2 µm) size starch granules. The pasting properties were significantly (p ≤ 0.05) different for different cereal starches. Peak, breakdown, and final viscosities were the highest for maize starch (1725, 384, and 2112 mPa.s, respectively), whereas rice and oats exhibited the highest trough and setback viscosities (1420 and 954 mPa.s, respectively).     

In vitro Digestibility of Raw Starches Extracted from five Yam (Dioscorea spp.) Species Grown in Jamaica

Starch granules from Round leaf yellow yam, Negro yam, Sweet yam, Bitter yam and Chinese yam grown in Jamaica were isolated and characterized. The amylose content, granular size, crystallinity, and digestibility by α‐amylase were determined. The granules obtained were of three crystalline types. Round leaf yellow yam, Negro yam and Sweet yam were found to be type‐B, while Chinese yam and Bitter yam were type‐C and type‐A, respectively. Round leaf yellow yam had the highest amylose content (26.5%) while Chinese yam had the lowest (11.1%). The granule size varied between 1–3 μm for Chinese yam and 16–42 μm for Round leaf yellow yam. Significant variations in digestibility of the granules were observed. Raw starches from Chinese yam and Bitter yam were the most susceptible to α‐amylase digestion (porcine pancreatic α‐amylase, pH 5.5, 0.02% CaCl₂, 40°C, 24 h) with 21.27 ± 0.01% and 18.11 ± 0.02% degradation, respectively, while Round leaf yellow yam, Negro yam and Sweet yam starches were the least susceptible, with 13.74 ± 0.03%, 14.98 ± 0.08%, and 15.32 ± 0.04% enzymatic degradation, respectively.     

杂粮原料对其挂面淀粉消化性的影响及内在因素研究

本文以五种杂粮粉为原料,通过体外模拟消化试验研究了杂粮原料对其挂面体外淀粉消化特性和估计血糖生成指数（eGI）的影响。结果表明：杂粮挂面的eGI值由高到低为：大麦>青稞>苦荞>燕麦>高粱。采用差示扫描量热仪、傅里叶红外光谱仪和X射线衍射仪等手段分析了杂粮挂面淀粉理化特性差异。高粱糊化温度和焓值显著高于其他杂粮（P<0.05）;燕麦和高粱挂面直链淀粉含量和淀粉相对结晶度较高,且具有较多短程有序结构和较强氢键强度。采用组分分离法探究了内源性酚类物质和脂肪对挂面消化特性的影响,内源性多酚和脂肪的脱除使面条淀粉消化率明显升高。该研究为开发低GI食品提供了参考依据。     

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).     

Relationship between the structure,physicochemical properties and in vitro digestibility of rice starches with different amylose contents

The in vitro digestibility and molecular and crystalline structures of rice starches (Long-grain, Arborio, Calrose, and Glutinous) differing in amylose content were investigated and the relationship between the structure and in vitro digestibility of starch was studied. Long-grain showed the highest amylose content (27.2%), whereas Glutinous showed the lowest amylose content (4.2%). Long-grain had the highest average amylopectin branch chain length (18.8) and proportion (8.7%) of long branch chains (DP ≥ 37), and the lowest proportion (26.9%) of short branch chains (DP 6–12). Among the non-waxy rice starches (Long-grain, Arborio, and Calrose), Calrose had the lowest average chain length (17.7) and the lowest proportion (7.1%) of long branch chains (DP ≥ 37). The relative crystallinity of rice starch followed the order: Glutinous (33.5%) > Calrose (31.4%) > Arborio (31.0%) > Long-grain (29.9%). Long-grain had the highest gelatinization temperature and the lowest gelatinization temperature range, whereas Glutinous showed the highest gelatinization temperature range and gelatinization enthalpy. Arborio had the highest melting enthalpy for amylose–lipid complex among the tested rice starches. Pasting temperature, setback, and final viscosity increased with increasing amylose content, whereas the peak viscosity and breakdown showed negative correlations with amylose content. The rapidly digestible starch (RDS) content of the tested rice starches followed the order: Glutinous (71.4%) > Calrose (52.2%) > Arborio (48.4%) > Long-grain (39.4%). Contrary to this, the slowly digestible starch (SDS) and resistant starch (RS) contents showed an opposite trend compared to RDS. Digestibility (RDS, SDS, and RS) of the rice starches was significantly correlated (p ≤ 0.05) with amylose content, proportions of DP 6–12 and DP 13–24, relative crystallinity, intensity ratio (of 1047 cm⁻¹ to 1022 cm⁻¹ from Fourier transform infrared spectroscopy), swelling factor, amylose leaching, onset temperature of gelatinization, gelatinization temperature range, gelatinization enthalpy, pasting temperature, peak viscosity, breakdown, setback, and final viscosity.     

Comparison of structural features and in vitro digestibility of purple yam (<Emphasis Type="Italic">Dioscorea alata</Emphasis> L.) resistant starches by autoclaving and multi-enzyme hydrolysis

Resistant starches (RS) were prepared from purple yam by dual autoclaving-retrogradation (DAS), and pullulanase debranching treatment (PDS). DAS and PDS were then hydrolyzed by α-amylase and amyloglucosidase to obtain DAS.H and PDS.H. Differences in structural characteristics and in vitro digestibility among the four samples were investigated. The results showed that granules of RS had a rough surface and irregular shape. DAS had the lowest amylose content (29.52%), whereas PDS.H had the highest amylose content (41.96%). The order of crystallinity of the RS was: PDS.H (31.23%) > DAS.H (30.16%) > PDS (21.23%) > DAS (15.30%). Analysis by in vitro digestibility indicated a decreased hydrolysis index and glycemic index due to lower swelling power and water-binding capacity, and a well-ordered double helix structure and more crystallization in PDS.H than in the other RS samples. These results suggest that pullulanase debranching combined with α-amylase and amyloglucosidase hydrolysis may produce better RS with improved crystalline structure and higher digestion resistibility.     

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。     

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.     

Characteristics of Different Types of Starch in Starch Noodles and Their Effect on Eating Quality

Several commercial starch noodles made from legume, tuber, geshu (kudzu and sweet potato) and fernery starches were used to study the characteristics of starch in starch noodles and their effect on eating quality of starch noodles. Scanning electron microscopy observation found that the special inner structure of starch noodles was composed of some broken starch granules and some gel-like substances. Tuber and legume starches had the highest and lowest solubility, swelling power, swelling factor, setback, breakdown, peak viscosity, and final viscosity, respectively. Legume and tuber starches had the highest and lowest gelatinization temperature, respectively. Tuber and geshu starches had the highest amylose leaching rate, while legume starches owned the lowest value (p < 0.05). Tuber starches had the highest conclusion temperature of gelatinization (151.12~158.86°C). Fernery starches had the lowest value of retrogradation enthalpy (967.33 J/g dry starch). Legume starch noodles had the lowest broken rate (0.00~1.67%), swelling ratio (332.64~343.57%), and cooking loss (2.40~2.74%), and the highest hardness (87.47~93.29 g/mm2), shear deformation (0.49~0.52), and elasticity (0.58~0.62), However, tuber and fernery starch noodles did the opposite, tuber and legume starch noodles had the highest and lowest cohesiveness, respectively. All the above cooking and starch properties test results of starch noodles demonstrated that, compared with others, legume starch noodles are relatively well in eating quality. The correlation analysis showed that the cooking and physical quality of starch noodles could be perfected significantly by improving the swelling and pasting properties for starch of starch noodles, while thermal properties had no obvious influence on them.     

Chemical composition,digestibility and emulsification properties of octenyl succinic esters of various starches

Octenyl succinate starches are commonly used as emulsifiers and texturizing agents in many food-systems. Rice, tapioca, corn, wheat and potato starches were modified with octenyl succinic anhydride (OSA) at 3% level. Structural characterization, molecular weight, starch digestibility and physical properties of starch granule stabilized emulsions were studied for modified starches. Modified potato (0.022) and wheat (0.018) starches had the highest and lowest degrees of OSA substitution, respectively. For all starches, amylose and amylopectin molecular mass was significantly (P < 0.05) lower for OSA starches. OSA modification may have hydrolyzed the small amylose and amylopectin chains, or caused rearrangement of the starch molecules. Although the starch modification improved emulsification properties, botanical source showed more influence on this parameter. Overall, botanical source had more influence on functional properties than degree of substitution. Further studies on OSA group distribution and fine molecular structure of amylopectin and relationship with functional properties will be important.     

Morphological,thermal and rheological properties of starches separated from rice cultivars grown in India

Morphological, thermal and rheological properties of starches separated from five rice cultivars (PR-106, PR-114, IR-8, PR-103 and PR-113), varying in amylose content, were studied. Amylose contents of starches separated from PR-103, IR-8, PR-106, PR-114 and PR-113 were 7.83, 15.62, 16.05, 16.13 and 18.86%, respectively. The granular size, measured using a Scanning Electron Microscope, varied from 2.4 to 5.4 μm in all rice starches. PR-103 starch, with lowest average granular size, amylose content and solubility, had the highest swelling power, while PR-113 starch, with the highest average granular size and amylose content had the lowest swelling power. PR-103 starch showed highest transition temperatures, enthalpies of gelatinization, peak height index, range and enthalpies of retrogradation. The retrogradation (%) was observed to be highest in PR-113 starch and lowest in PR-103 starch. The changes in rheological parameters of rice starches during heating were measured using a Dynamic rheometer. PR-113 rice starch showed the highest G′, G″ and breakdown in G′ values, whereas PR-103 starch showed the lowest values for these parameters. Turbidity value of gelatinized pastes from all rice starches progressively increased up to the 3rd day during refrigerated storage, PR-103 starch paste showed the lowest turbidity value and PR-113 starch showed the highest value. The syneresis (%) of starch pastes, from different rice cultivars during storage at 4 °C, was also measured. The syneresis of starch pastes from all rice cultivars, except PR-103, increased with storage. PR-103 starch paste showed negligible syneresis during storage.     

Formation of starch spherulites: Role of amylose content and thermal events

Commercial maize starches and potato starches of two cultivars differing in physicochemical composition (granule size distribution; amylose to amylopectin ratio) and crystallinity were heated to 180 °C and then cooled by fast quench using a differential scanning calorimeter (DSC), in order to produce spherulitic starch morphologies. Among the raw maize starches, waxy maize starch had highest relative crystallinity (49%) whereas a lowest crystallinity of 33–39% was calculated for high-amylose maize starches. Potato starches showed a relative crystallinity of 50%. The temperatures and enthalpies of gelatinisation and melting varied among all the starches. High-amylose maize starches showed higher transition temperatures of gelatinisation (T_gel), whereas waxy maize starch had lowest T_gel and enthalpy of gelatinisation (ΔH_gel). Similarly, a considerable variation in parameters related with crystalline melting (T_m1, T_m2 and ΔH_m1, ΔH_m2) was observed for different starches. The superheated gels of different starches treated using DSC were subjected to polarised microscopy, to confirm the formation of spherulites. Both the high-amylose starch gels showed the presence of spherulites exhibiting birefringence and a weak crystalline pattern. No birefringence was observed for waxy maize starch gel, while potato starch gels had some birefringence. The particle size distribution of high-amylose maize starch gels analysed through Zetasizer showed the sizes of spherulitic particles fall in the range of 300 nm–900 nm. The scanning electron micrographs of the dried high-amylose maize starch gels showed the presence of round spherulites consisting of several aggregated spherulitic particles. Amylose content and melting of crystallites during heating play an important role during recrystallisation of amylose (spherulite morphologies).     

Microstructural and physicochemical properties of heat-moisture treated waxy and normal starches

Starches from normal rice (21.72% amylose), waxy rice (1.64% amylose), normal corn (25.19% amylose), waxy corn (2.06% amylose), normal potato (28.97% amylose) and waxy potato (3.92% amylose) were heat-treated at 100 °C for 16 h at a moisture content of 25%. The effect of heat-moisture treatment (HMT) on morphology, structure, and physicochemical properties of those starches was investigated. The HMT did not change the size, shape, and surface characteristics of corn and potato starch granules, while surface change/partial gelatinization was found on the granules of rice starches. The X-ray diffraction pattern of normal and waxy potato starches was shifted from B- to C-type by HMT. The crystallinity of the starch samples, except waxy potato starch decreased on HMT. The viscosity profiles changed significantly with HMT. The treated starches, except the waxy potato starch, had higher pasting temperature and lower viscosity. The differences in viscosity values before and after HMT were more pronounced in normal starches than in waxy starches, whereas changes in the pasting temperature showed the reverse (waxy > normal). Shifts of the gelatinization temperature to higher values and gelatinization enthalpy to lower values as well as biphasic endotherms were found in treated starches. HMT increased enzyme digestibility of treated starches (except waxy corn starch); i.e., rapidly and slowly digestible starches increased, but resistant starch decreased. Although there was no absolute consistency on the data obtained from the three pairs of waxy and normal starches, in most cases the effects of HMT on normal starches were more pronounced than the corresponding waxy starches.     

Physicochemical, pasting and thermal properties of tuber starches as modified by guar gum and locust bean gum

This study was carried out in order to compare the functional characteristics of isolated starch from five tuber crops, yam, taro, sweet potato, yam bean and potato, as well as effect of guar gum (GG) and locust bean gum (LBG) on pasting and thermal properties of tuber starches. The results showed that total amylose content of five tested starches ranged from 17.85% to 30.36%. The results of pasting behaviour showed that potato starches exhibited the highest peak viscosity and yam starch presented a stable curve with little breakdown viscosity. Addition of GG and LBG resulted in a significant increase in peak, final viscosity, breakdown and setback viscosity for all tuber starches ( P  < 0.05), but a slight decrease in pasting temperature. The gelatinisation enthalpy (Δ H ) for starches with GG and LBG was slightly lower than those of the starches alone in yam and sweet potato, but not in taro and yam bean.     

Fundamental and Derived Properties of Yam (Dioscorea Spp.) Starch Powders and Implications in Tablet and Capsule Formulation

A comparative investigation of the fundamental and derived properties of starches from some species of yam (Dioscorea spp.) was conducted with a view to establishing their suitability as excipients in tablet and capsule formulations. Variations were observed in the mean granular diameter of the starches obtained from the different Dioscorea species. Granular diameter ranged from 5.4 µm (Chinese yam) to 34.5 µm (Round leaf yellow yam). Chinese yam and Bitter yam had the highest specific surface area (625.91 m²/kg and 258.76 m²/kg, respectively) while Round leaf yellow yam and Negro yam had the lowest (117.4 m²/kg and 154.34 m²/kg, respectively). Chinese yam had the lowest granular volume (6.00 µm³), surface area (5.67 µm²) and granule surface‐mean diameter (6.74 µm), while Round leaf yellow yam had the largest mean granular diameter, highest granular volume (35.2 µm³), surface area (34.8 µm²) and granule surface mean diameter (35.88 µm). Particle size distribution plots of Chinese yam, Round leaf yellow yam and Negro yam displayed a Gaussian size distribution pattern while Bitter yam displayed a negatively skewed distribution. The variations observed in the granular size and shape may influence the observed derived properties of the starches.     

Gel Textural Characteristics of Corn,Cassava and Yam Starch Blends: A Mixture Surface Response Methodology Approach

Blends of native starches can be used to obtain special sensory properties avoiding the use of chemically modified starches. The mixture design approach was used to analyze the textural properties (hardness, adhesiveness, cohesiveness and gumminess) of gels obtained with different proportions of yam, corn and cassava starches (6% total solids) and related to microstructural characteristics. Maximum limits of 60% yam starch and 70% corn starch and minimum level of 30% cassava starch were fixed to minimize syneresis under storage. Hardness, adhesiveness and gumminess increased with the proportion of corn starch in the blends. The lowest values of hardness corresponded to the blends containing higher proportions of cassava starch, that has the lowest amylose content. Corn starch was the component that less contributed to cohesiveness. The characteristic high cohesiveness of cassava starch pastes (related to its higher amylopectin content) was reduced when it was mixed in adequate proportions with yam and/or corn starches. Gels containing only yam starch presented syneresis values close to 40% after 24° h storage at 4°C; the decrease of the maximum level of yam starch to 60% as well as the inclusion of cassava starch in the blends reduced weight losses. Disadvantages found in gels containing individual starches, such as exudate in yam and corn starch gels, and excessive cohesiveness in cassava starch gels, are minimized improving their possible applications, when blends are used.     

有机五色小米淀粉的精细结构、理化性质和消化性研究

目的 本研究通过从有机红谷小米、绿小米、白小米、金苗小米和黑小米中分别分离纯化制备得到有机五色小米淀粉。方法 利用现代分析仪器测定五色有机小米淀粉的形貌特征、结晶结构、功能特性和消化特性。利用体积排阻色谱分析法(Size exclusion chromatography,SEC)与荧光辅助毛细管电泳法(Fluorescence assisted capillary electrophoresis, FACE)测定五种有机小米的直链淀粉含量和支链淀粉的链长分布。构建有机五色小米淀粉精细结构与理化特性,功能特性和消化性之间的关联。结果 体外斜率对数法(Log of Slop,LOS)消化性结果表明,有机五色小米淀粉的最终消化率(C₁₂₀)差别并不明显,其中黑小米淀粉的C₁₂₀最低(72.23±4.97%),金苗小米淀粉的C₁₂₀最高(78.15±0.40%),其次依次为白小米>绿小米>红谷小米。有机五色小米淀粉中绿小米淀粉最易糊化,与自身支链淀粉的短链分布有关。有机黑小米淀粉糊化峰值温度最高,金苗小米次之,与其结晶度及直链淀粉含量有关。黑小米淀粉的峰值粘度最低,最难糊化,与支链淀粉的平均链长较长难断裂有关。有机五色小米淀粉结晶度整体差异不大,半结晶结构中红谷小米的松散程度最大。结论 研究不同品种有机小米淀粉的差异性,为人们科学饮食搭配及个性化营养提供重要参考价值。     

Characteristics of menthone encapsulated complex by mungbean,tapioca, and rice starches

In order to use commercial starch for flavor encapsulation, three starches (mungbean, rice, and tapioca) were selected to determine their ability to form inclusion complex with menthone. Mungbean starch had the highest amylose content, followed by rice starch and tapioca starch, respectively. After complexation, appearance and microstructure changes were observed for all starches. Mungbean and tapioca complexes with well-organized V7 crystalline pattern gave similar menthone entrapment (around 4%) which was higher than that of the rice sample (<1%). Molecular size distribution of the complexes revealed the role of amylose fractions for both mungbean and tapioca complexes. According to differential scanning calorimetric analysis, menthone complexes formation was confirmed by a thermoreversible event. Regarding the high yield of starch precipitate and menthone entrapment, mungbean starch is considered a more suitable material for menthone encapsulation rather than tapioca and rice starches.     

4种杂豆淀粉结构特征和理化特性比较

以4种我国广泛种植的杂豆为原料，采用湿磨法提取豇豆淀粉、扁豆淀粉、豌豆淀粉、红芸豆淀粉，并对4种杂豆淀粉的结构特征和理化特性进行比较。结果表明：杂豆淀粉的红外光谱均呈现典型的淀粉类多糖结构特征，颗粒完整光滑，主要呈现肾型和椭圆形。样品的平均流体力学半径大小顺序为豇豆淀粉>豌豆淀粉>扁豆淀粉>红芸豆淀粉，扁豆淀粉为CC-型晶体，其余为C_A-型晶体，样品间的相对结晶度差异较大(27.6%～38.5%)。4种杂豆淀粉的糊化特性差异显著，糊化温度均较高(75.3～82.8℃)，不易糊化。豇豆淀粉直链淀粉含量最低(26.3%)，其热糊稳定性优于其他杂豆淀粉，具有不易老化的特性。红芸豆淀粉的直链淀粉含量最高(31.5%)，回生值最高(3 182.3 mPa·s)，最易发生老化行为。综上，4种杂豆淀粉的颗粒形貌相似，均为C-型晶体，分子结构和糊化特性差异较大，凝沉特性相近。     

不同品种山药蒸制过程中淀粉消化率及抗氧化活性

本实验以不同品种山药的淀粉相关特性、生物活性成分、抗氧化能力和微观结构为评价指标,研究蒸制时间对铁棍山药、淮山药、糯山药3 种山药的营养品质和抗氧化活性的影响,并探究山药微观结构和品质变化的内在联系。结果表明,蒸制处理后,3 种山药样品中的总淀粉质量分数和抗性淀粉质量分数均显著减少（P＜0.05）,但可消化淀粉（快消化淀粉和慢消化淀粉）及表观直链淀粉质量分数显著增加（P＜0.05）,同时山药淀粉的持水力增强,溶解度下降。3 种山药中,蒸制15 min的淮山药总可溶性多酚和总黄酮含量最高,分别为1.04 mg/g和0.83 mg/g,同时,其抗氧化能力也最强,铁离子还原力、1,1-二苯基-2-苦基肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除率和羟自由基清除率分别为165.56 μmol/g、58.15%和82.26%。扫描电子显微镜观察发现,蒸制后山药样品颗粒呈特征性的块状和不规则的结构,表面粗糙并有裂缝。综合比较,蒸制时间对3 种山药样品的品质特征及活性成分的影响差异较大,蒸制15 min后山药样品的总可溶性多酚和总黄酮含量最高,抗氧化活性也最强,蒸制20 min后山药样品中的可消化淀粉含量较高,而生山药的微观结构特征较好,说明适度蒸制可以提高山药淀粉的消化率和山药的抗氧化能力。