锥栗变性淀粉的热特性与结晶结构

应用差示扫描量热仪和X-射线衍射仪,研究了锥栗变性淀粉的热特性和结晶特性。结果表明:与原淀粉(或多孔淀粉)相比,交联淀粉(或交联多孔淀粉)糊的抗老化性、抗剪切性、抗酸性和冻融稳定性均有较大提高;锥栗原淀粉、多孔淀粉、交联淀粉和交联多孔淀粉糊化焓依次增高,而多孔淀粉、原淀粉、交联多孔淀粉和交联淀粉的糊化温度则依次增高;锥栗交联淀粉、原淀粉、交联多孔淀粉和多孔淀粉的结晶度、微晶尺寸依次增加,而微晶间距依次缩小。     

小红栲淀粉糊特性研究

采用偏光显微镜、分光光度计、旋转粘度计等现代分析仪器,对小红栲淀粉糊特性进行了较详细的研究。结果表明,小红栲淀粉的糊化温度为65.5～79.5℃;小红栲淀粉糊具有酶解率较高、透明度低、凝沉稳定性较强、冻融稳定性较好的特性;在pH6.0～8.0范围内小红栲淀粉糊粘度较高,温度和转速对糊粘度有一定影响,浓度对糊粘度有显著影响。     

小红栲抗性淀粉的理化功能特性

以小红栲原淀粉(NS)为对照,研究了两种小红栲抗性淀粉(RS)的体外消化特性、结构特性、糊特性和益生特性。结果显示:与原淀粉对比,小红栲湿热处理抗性淀粉(HMT RS)与酸解—湿热处理抗性淀粉(AH-HMT RS)的RS含量显著增加,属于低血糖指数(pGI)食品配料。HMT RS与AH-HMT RS的晶体结构以B-型晶体占优且平均聚合度都降低,前者的微观结构呈规则片层结构,而后者的则呈小片层散乱堆积结构。HMT RS和AHHMT RS糊的峰值黏度、谷值黏度、冷却黏度、崩解值与回值均显著降低,特别是AH-HMT RS糊的峰值黏度、谷值黏度与冷却黏度均降至14mPa·s以下,两者都只能形成低强度凝胶。HMT RS和AH-HMT RS的起始糊化温度、峰值糊化温度、终止糊化温度和糊化温度范围都显著增加,糊化焓则显著减少。以HMT RS或AHHMT RS作为唯一碳源时,后者比前者对双歧杆菌、乳酸杆菌的增殖作用更强,丁酸产生也更多。     

短链菊粉对玉米磷酸酯双淀粉热力学特性的影响

通过添加不同比例的短链菊粉（inulin,I）,研究其对玉米磷酸酯双淀粉（maize distarch phosphate,MDP）质构、糊化特性和热力学性质的影响。采用质构仪、Brabender黏度计和差示扫描量热仪（differentialscanning calorimeter,DSC）分别测定了菊粉、MDP及两者复配物的凝胶质构特性、黏度特性、糊化及相变特性等参数。结果表明：菊粉的添加增加了玉米磷酸酯双淀粉的凝胶强度、黏附力、硬度、回复性及糊化起始温度（To）、峰值温度（Tp）和终止温度（Tc）,当I和MDP质量比为3∶7时,复配物凝胶的黏附力、硬度和回复性较MDP依次增加了33%、145%和650%,To和Tp值分别增加了5.06%和5.10%;菊粉的添加降低了MDP的峰值黏度、崩解值、回生值及糊化吸热值,当I和MDP质量比为3∶7时,峰值黏度、崩解值和回生值较MDP依次降低了73.43%、87.35%和79.32%。综合来看,菊粉增强了MDP凝胶的稳定性和强度,提高了MDP的糊化温度、糊液黏度和糊液稳定性,同时有效抑制了MDP的回生。     

氯化钠对不同品种红小豆淀粉特性的影响

从3种不同品种的红小豆中提取的淀粉为原料,通过分析淀粉及添加氯化钠后的淀粉糊的粒径、黏度值、回生值、热焓值、凝胶性等特性,探究氯化钠对淀粉糊化特性的影响。结果表明:低直链淀粉含量的大红袍中淀粉相较于宝清红和珍珠红淀粉,表现出较高的糊化起始温度、最终黏度、热焓值;较低的峰值黏度、较小的粒径;对比添加2%氯化钠前后,3种红小豆淀粉糊化后的平均粒径、峰值黏度、衰减值和回生值显著下降(P0.05);糊化温度、淀粉的凝沉性显著增大(P0.05);氯化钠对凝胶特性的影响体现在凝胶强度显著降低(P0.05),同时淀粉凝胶的黏度减小。     

蔗糖对不同品种赤小豆淀粉性能的影响

以三种不同赤小豆淀粉为原料,通过分析添加蔗糖前后淀粉的糊化性能、热力学性能、消化性能等特性,探究蔗糖对淀粉性能的影响。结果表明：直链淀粉含量较高的珍珠红赤小豆淀粉,具有较大的粒径、较高的峰值黏度和回生值,但其糊化温度和最终黏度较低;当添加10%的蔗糖后,三种淀粉的平均粒径、峰值黏度、凝沉性和快速消化淀粉（Rapidly digestible starch,RDS）显著降低（P<0.05）,而三种淀粉的糊化温度、热焓值、回生值和衰减值却显著增加（P<0.05）;慢速消化淀粉（Slowly digestible starch,SDS）含量除珍珠红赤小豆淀粉外均显著增加（P<0.05）,淀粉凝胶性以及抗性淀粉（Resistant starch,RS）虽有下降,但不显著。蔗糖的添加促进了赤小豆淀粉的回生;抑制了淀粉的糊化、降低了抗老化性和消化性。     

黑曲霉发酵法制备小红栲多孔淀粉

对黑曲霉发酵法制备小红栲多孔淀粉的工艺进行了研究,并分析了多孔淀粉的形态结构、晶体特征和糊化特性。试验结果表明,在发酵培养基母液体积分数为90%的培养基中,当黑曲霉发酵至第48 h时,加入质量分数为7.0%的原淀粉后继续发酵56 h,由此制得小红栲多孔淀粉。小红栲多孔淀粉的形成过程是:酶作用于淀粉颗粒表面的凹坑形成孔洞,由浅入深,直达颗粒中心,最终形成彼此相连的桥形网状空洞结构,其上分布着孔径1μm左右的孔洞。小红栲原淀粉与多孔淀粉的X-射线衍射图谱由尖峰衍射特征和弥散衍射特征两部分组成,属C-型晶体。多孔淀粉比原淀粉的结晶度、微晶尺寸和吸热焓要大,而微晶间距和糊化温度则小。     

武陵山区4种块根类淀粉的糊化特性和冲调性质分析

目的:探究葛根、蕨根、百合、凉薯4种块根类植物淀粉的糊化特性与冲调特性。方法:采用扫描电子显微镜(SEM)、快速黏度分析仪(RVA)、差式量热扫描仪(DSC)等分析淀粉的微观形态和糊化特性;对4种淀粉进行冲泡,并分析淀粉糊的透明度和表观形态等。结果:葛根、蕨根、凉薯淀粉的颗粒形态较为相似,大多为球形;百合淀粉颗粒较大,且形态为纺锤形。糊化特性表明,百合淀粉的峰值黏度最高,为(7.00±0.03) Pa·s;葛根和百合淀粉的回生值较大,表明其易于回生。热力学特性表明,蕨根淀粉的起始糊化温度最低,为59.4℃,表明其容易糊化;百合淀粉的糊化焓值最高,为15.64 J/g,表明其糊化时需要更多的热量。冲调特性表明,葛根淀粉糊的透明度最好,其透光率为29.11%;而百合淀粉糊的透光率仅为12.25%;冲调后,葛根淀粉糊和百合淀粉糊易于形成凝胶,但流动性较差;蕨根淀粉糊和凉薯淀粉糊凝胶能力较差,易于流动。结论:百合淀粉和葛根淀粉的冲调性质相似,具有冲调类食品的开发潜力;蕨根淀粉和凉薯淀粉回生值较低,糊的流动性较好,可用于抑制食品的回生。     

交联和羟丙基改性对蜡质玉米淀粉糊化和流变性质的影响

以蜡质玉米淀粉为原料,制备了交联淀粉、羟丙基淀粉和交联羟丙基淀粉,通过扫描电子显微镜、X-射线衍射仪、快速黏度仪和流变仪等现代分析仪器分析了淀粉的结构、糊化性质和流变特性,探究了交联和羟丙基改性对淀粉的糊化和流变学性质的影响。结果表明:交联改性降低了淀粉的峰值黏度,增大了淀粉成糊温度、稠度系数和抗剪切性,淀粉黏弹性得到明显改善;羟丙基改性淀粉的峰值黏度提高,成糊温度、抗剪切性和结晶度降低,淀粉颗粒结构破坏;交联羟丙基改性淀粉具有交联淀粉的糊化和流变特性,但成糊温度和结晶度降低。     

柠檬酸和NaCl对变性淀粉糊化性质的影响

采用快速粘度分析仪(RVA)测定了蜡质玉米淀粉、交联淀粉、羟丙基淀粉和交联羟丙基淀粉的糊化性质,研究了不同淀粉质量分数及同一质量分数下氯化钠和柠檬酸对淀粉糊化性质的影响。结果表明,淀粉乳质量分数和氯化钠对交联淀粉和交联羟丙基淀粉的峰值黏度、终值黏度和回生值影响较大,而柠檬酸对蜡质玉米淀粉和羟丙基淀粉的峰值黏度、终值黏度和崩解值影响较大。随着淀粉乳质量分数的增大,淀粉的峰值黏度、终值黏度、崩解值和回生值均增大,成糊温度降低。随着氯化钠质量分数的增大,淀粉的峰值黏度、终值黏度、崩解值和回生值增大,成糊温度先增大后减小,并在氯化钠质量分数为10%时达到最大值。随着柠檬酸质量分数的增大,淀粉的终值黏度和回生值减小,崩解值增大,成糊温度不变。     

Gelatinization and Retrogradation Properties of Native and Hydroxypropylated Crosslinked Tapioca Starches with Added Sucrose and Sodium Chloride

The effects of sucrose and sodium chloride on the gelatinization and retrogradation of native and hydroxypropylated crosslinked tapioca starches were investigated by using Differential Scanning Calorimetry (DSC). Hydroxypropylated crosslinked tapioca starches showed low gelatinization temperature and enthalpy compared to the native tapioca starch. Sucrose and sodium chloride increased the gelatinization temperatures of all starch samples. The enthalpy to melt retrograded amylopectin of hydroxypropylated crosslinked tapioca starches were low, compared to that of the native starch. Sucrose did not have much effect on retrogradation of the starch, while sodium chloride decreased retrogradation of all starch samples.     

Physicochemical characterization of chemically modified corn starches related to rheological behavior,retrogradation and film forming capacity

An integral approach of chemical modification effects on physicochemical and functional properties of corn starch was performed using different and complementary techniques. Acetylated, acetylated crosslinked, hydroxypropylated crosslinked, and acid modified corn starches were analyzed. Substitution and dual modification reduced significantly amylose concentration. Chemical modification decreased granules crystallinity degree. A significant increase in swelling power was observed in substituted and dual modified starches at 90 °C, besides these treatments decreased gelatinization temperature and enthalpy. Acid modified starch pastes showed a Newtonian behavior while substituted and dual modified ones exhibited a viscoelastic response. Dynamic rheological properties of modified starch pastes were not affected by post gelatinization time while native starch pastes developed a more rigid structure during storage. Retrogradation of substituted starch pastes after 12 days at 4 °C was reduced, since syneresis degree and hardness increase were significantly lower than those of native pastes. It was demonstrated that only substituted and native starches exhibited film forming capacity.     

Preparation and physicochemical properties of modified jackfruit starches

Modifications of jackfruit starch, extracted from the cotyledons of Artocarpus heterophyllus Lam. (Thong Prasert cultivar), were carried out to obtain a pregelatinized starch, three (m-, n- and i-) carboxymethyl starches, a hydroxypropyl starch and a phosphate cross-linked starch. Physicochemical properties of native and modified jackfruit starches were comparatively investigated. Pregelatinized, hydroxypropyl, and cross-linked starches were insoluble or partially soluble in water at room temperature, while carboxymethyl starches were soluble with good overall water uptake. Scanning electron microscopic images revealed that granules of most modified jackfruit starches retained the native appearance and crystal structure, with the exception of pregelatinized starch and two (n- and i-) carboxymethyl starches, which showed significant breakage of granules. X-ray diffraction patterns corroborated to suggest the loss of crystallinity in these modified starches. Thermal analysis showed a significant decrease in the gelatinization temperature of hydroxypropyl starch with no change in enthalpy, while higher gelatinization temperature and less enthalpic value were observed for pregelatinized starch. Pregelatinized and hydroxypropyl starches showed temperature-dependent improvement on swelling and solubility, while cross-linked starch exhibited less solubility. Aqueous solution of m-carboxymethyl starch yielded the highest apparent viscosity with improved heating-cooling stability.     

Physico-chemical properties of flour and starch from jackfruit seeds (Artocarpus heterophyllus Lam.) compared with modified starches

Jackfruit (Artocarpus heterophyllus Lam.) is one of the most popular tropical fruits grown in Asia. The objective of this study was to compare physico‐chemical properties of native flour and starch from jackfruit seeds (A. heterophyllus) to commercially modified starches (Novation 2300 and Purity 4). The colour of jackfruit seed starch was lighter than the Novation 2300 starch but darker than the Purity 4 starch. The jackfruit seed starch had a narrower gelatinization temperature range than Purity 4 and required less gelatinization energy compared with modified starches. The peak viscosity of jackfruit seed starch was lower than commercially modified starches. Likewise, setback viscosity, swelling power and solubility of jackfruit seed starch showed similar trends. Results from this study suggest that native starch from jackfruit seed could be used as an alternative for modified starches in a system needing starch with a high thermal and/or mechanical shear stability.     

改性玉米淀粉的物理化学研究

对天然玉米淀粉和五种化学改性玉米淀粉的糖化性质进行了比较。改性玉米淀粉包括下列五种,磷酸淀粉,交联磷酸淀粉,醋酸淀粉A,醋酸淀粉B和羟丙基淀粉。使用差热扫描量热计测定了糊化的热力学参数,同时用显微镜观察了糊化过程。研究表明,五种改性玉米淀粉的糊化热都比天然的玉米淀粉小,测量冷的淀粉糊的流动性质表明只有羟丙基玉米淀粉比天然玉米淀粉的帖度高。     

Enzymatic hydrolysis of granular native and mildly heat-treated tapioca and sweet potato starches at sub-gelatinization temperature

The effect of mild heat treatment (below gelatinization temperature) towards the susceptibility of granular starch to enzymatic hydrolysis was investigated. Tapioca and sweet potato starches were subjected to enzymatic hydrolysis with a mixture of fungal α-amylase and glucoamylase at 35 °C for 24 h. Starches were hydrolyzed in native (granular) state and after heat treatment below gelatinization temperature (60 °C for 30 min). The dextrose equivalent (DE) value of heat-treated starch increased significantly compared to native starch, i.e., 36–50% and 27–34% for tapioca and sweet potato starch, respectively. Scanning electron microscopy examination showed that enzymatic erosion occurred mainly at the surface of starch granules. Hydrolyzed heat-treated starch exhibited rougher surface and porous granules compared to native starch. X-ray analysis suggested that enzymatic erosion preferentially occurred in amorphous areas of the granules. The amylose content, swelling power and solubility showed insignificant increase for both starches. Evidently, heating treatment below gelatinization temperature was effective in enhancing the degree of hydrolysis of granular starch.     

甘薯交联抗性淀粉热力学性质与消化性研究

根据膨胀度、糊化度及差示扫描量热仪(DSC)测得热力学参数,综合分析甘薯交联抗性淀粉和原淀粉热力学性质,并采用Jenkins提出In–vitro模型测定淀粉体外消化性。结果表明:在同一温度下,甘薯交联抗性淀粉膨胀度和糊化度均较原淀粉低,且交联剂用量越高,淀粉膨胀度和糊化度越小;DSC测试结果显示,甘薯交联抗性淀粉相转变温度To、Tp、Tc随交联剂用量增加而升高,Tc–To和△H均比原淀粉低。In–vitro消化模拟实验表明,甘薯交联抗性淀粉消化性比原淀粉低,并随交联剂含量增加,消化产物量减少,消化速度降低。     

Influence of prior acid treatment on physicochemical and structural properties of acetylated sorghum starch

Influence of prior acid treatment on acetylation of starch isolated from an Indian sorghum cultivar was investigated. The starch was acid thinned (AT) using 0.1, 0.5, and 1 M HCl for 1.5 h and then acetylated (Ac) with acetic anhydride (8% w/w). The acid thinning and subsequent acetylation appeared to reduce the percentage acetylation as indicated by degree of substitution. Ac‐AT starches exhibited significantly different physicochemical, thermal, pasting, and gel textural properties from those of AT and Ac starches. Starches after dual modification showed higher solubility, lower AM content, gelatinization temperatures, retrogradation, peak viscosity, and gel hardness than native starch. Enthalpy and range of gelatinization were observed to be higher in dual modified starches than native starch. However, no significant changes in granule morphology or crystalline pattern of Ac‐AT starches were observed compared with native starch.     

Characterization of amorphous granular starches prepared by high hydrostatic pressure (HHP)

Amorphous granular starches (AGS) and non-granular amorphous starches (non-AGS) of corn, tapioca and rice were prepared using high hydrostatic pressure (HHP) treatment with ethanol and water washing, respectively and their physicochemical properties were investigated. Water holding capacity and apparent viscosity of AGS and non-AGS were higher than those of native one in all starches. In RVA pasting properties, AGS and non-AGS showed higher pasting temperature and lower peak viscosity than those of native one. Furthermore, non-AGS showed distinctively lower peak viscosity compared to that of AGS possibly due to its non-granular structure. Apparent viscosity of non-AGS revealed relatively lower than commercial pre-gelatinized starch because of heat and pressure-induced gelatinization. Maintaining granular structure in HHP treated pre-gelatinized starch provide a distinctive physicochemical characteristics compared to native starch and preparation of gelatinized starch with different gelatinization and washing methods could cause big differences in their physicochemical properties.     

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.