不同介质条件对莲子淀粉糊黏度特性影响的研究

通过布拉班德黏度仪,研究淀粉浓度、不同pH值及浓度的糖(蔗糖、海藻糖、葡萄糖、果糖、高果糖浆)、盐(NaCl、KCl)对莲子淀粉糊黏度特性的影响。试验结果表明,随着淀粉浓度的增加莲子淀粉起糊温度降低,峰值黏度显著提高,热、冷稳定性下降,凝沉性增强。酸性条件(pH3.0)对莲子淀粉糊黏度特性影响显著。随着pH值的升高,热、冷稳定性和凝沉性均得到改善。加入糖时,莲子淀粉糊黏度提高,热、冷稳定性降低,凝沉性增强,而盐对莲子淀粉糊的影响小。     

海藻糖对大米淀粉回生特性的影响

为探究海藻糖对大米淀粉回生特性的影响,使用原子力显微镜、低场核磁共振、傅里叶变换红外光谱、差示扫描量热分析等方法,对淀粉分子结构、水分分布以及流变学和热力学特性进行了研究。结果表明:4℃回生3h和24h后,添加质量分数1.6%海藻糖的大米淀粉(T-淀粉)浸出的直链淀粉比大米淀粉分别降低了8.6%和11.5%。淀粉回生过程中分子链构象收缩,向有序规则化趋势排列,而添加海藻糖可以抑制分子构象的收缩。大米淀粉回生24h后有序程度增加了19.0%,而T-淀粉回生24h后有序程度仅比未回生淀粉增加了3.0%,海藻糖能显著降低大米淀粉体系的短程有序结构。T-淀粉与水分子的结合能力(强、弱结合水)显著高于大米淀粉(P<0.05)。T-淀粉体系中自由水的析出以及重结晶进程受阻,是抑制淀粉短期回生的原因之一。加入海藻糖后淀粉体系的回生焓和回生度均显著降低,且海藻糖带来的这种优势随着老化时间的延长越发凸显,T-淀粉体系长期回生的回生焓显著降低。因此,海藻糖不仅可以有效抑制淀粉的短期回生,对长期回生也有较好的抑制作用。     

水分含量对莲子淀粉回生影响及分子动力学模拟分析

采用差示扫描量热仪和X射线衍射仪对不同水分含量的糊化莲子淀粉的回生特性进行研究。结果表明,水分含量是影响淀粉回生的重要因素,其过高或过低对莲子淀粉的老化都有一定的抑制作用;当水分含量70%时,莲子淀粉最易重结晶,体系老化程度最高;分子动力学模拟系统探讨了不同水分含量淀粉老化模型的分子构象、水分子扩散系数、非共价键相互作用等参数的变化,发现在水分含量70%体系中,直链淀粉分子结构更趋于有序化、非共价键相互作用更强,这可在微观层面解释莲子淀粉回生的机理。     

淀粉酶对大米淀粉回生影响机理的研究

利用Avram i方程研究了淀粉酶对大米淀粉回生的影响机理,研究结果表明:对于籼米淀粉而言,β-淀粉酶的处理虽没有影响其重结晶的成核,但降低了重结晶的增长速率,因此回生受到抑制;对于糯米淀粉而言,β-淀粉酶的处理使其重结晶成核速度和增长速率都降低,回生受到有效抑制。对于籼米淀粉和糯米淀粉体系而言,普鲁兰酶的处理使两种淀粉重结晶的成核和结晶速率都增加,淀粉体系的回生被加速。     

制备过程中淀粉浓度对莲子回生淀粉理化特性的影响

本文从热稳定性、膨胀度及溶解度、黏度、流变特性等方面研究制备过程中淀粉浓度对莲子回生淀粉(Retrograded starch,RS)理化特性的影响。热重分析(Thermogravimetric analysis,TGA)结果表明,5%及40%淀粉浓度下的回生淀粉含有较多易挥发物质,20%淀粉浓度下的回生淀粉含有较多相对热稳定组分。随着淀粉浓度增加,莲子回生淀粉膨胀度减小,溶解度增大,黏度递减,且样品膨胀度及溶解度随温度升高而增加。由静态流变结果可知,所有样品均表现出剪切稀化特性,且5%、10%及20%淀粉浓度下的回生淀粉的黏度高于30%、40%及50%淀粉浓度下的回生淀粉的黏度;由动态流变结果可知,当角频率小于10 rad·s-1时,所有样品的储存模量均不受角频率影响;当角频率大于10 rad·s-1时,5%、10%及20%淀粉浓度下的回生淀粉的储存模量随角频率增加而减小,而30%、40%及50%淀粉浓度下的回生淀粉的储存模量随角频率增加而增大;所有样品的损失模量均随角频率升高呈上升趋势。综上,莲子淀粉回生行为受到回生过程中淀粉浓度的影响,并在理化性质上呈现差异。     

低聚果糖对大米淀粉回生特性的影响

为明确低聚果糖对大米淀粉回生特性的影响,以广泛报道的抗回生添加剂β-环糊精为对照,研究低聚果糖处理对大米淀粉的回生值、析水率、硬度、直链淀粉浸出量和动态流变学的影响,并利用傅里叶变换红外光谱、低场核磁共振、扫描电镜、X射线衍射和激光共聚焦扫描显微镜对大米淀粉的回生特性进行分析.结果 表明,与空白对照组(大米淀粉)相比,...     

魔芋胶对甘薯淀粉流变学特性及粉条品质的影响

研究多糖胶对淀粉糊化特性、老化特性、流变学特性及粉条食用品质的影响,为改善粉条品质提供理论指导。该文选择甘薯淀粉为原料,加入不同比例的魔芋胶,通过快速粘度仪(RVA)测定淀粉与魔芋胶复配体系粘度的变化来考察体系的糊化特性;用X衍射仪测定结晶度,评价体系的长期回生情况;通过流变仪考察魔芋胶对淀粉凝胶体系粘弹性的影响;最后评价魔芋胶对粉条食用品质的改善效果。结果表明:魔芋胶能够显著降低甘薯淀粉的糊化温度,提高粘度、崩解值和回生值,显著抑制淀粉的长期回生。甘薯淀粉/魔芋胶复配体系为屈服-假塑性流体,并且随着魔芋胶添加量的增加,屈服应力τ0、稠度系数K增加,流体指数n减小,复配体系有更好的粘弹性。甘薯淀粉和魔芋胶按质量比为8.5:1.5制备的粉条食用品质最佳。     

百合淀粉凝胶回生过程中的流变学特性

以玉米淀粉和马铃薯淀粉为参照,考察了百合淀粉回生过程中的流变学特性及糖对其回生过程中流变学特性的影响.结果表明百合淀粉回生过程中的流变学特性与马铃薯淀粉极为相似,与玉米淀粉有显著差异;添加蔗糖可以抑制百合淀粉胶存放过程中初始贮能模量的增加,即添加蔗糖可抑制其回生速率.     

莲子淀粉凝胶力学性能影响因素的研究

研究不同淀粉乳浓度、pH 值、NaCl 浓度、糖的种类以及吐温-80 浓度对莲子淀粉凝胶力学性能的影响。结果表明：随着淀粉乳浓度的增加,淀粉凝胶强度和弹性模量呈线性关系增加,而凝胶弹性增加不明显;随着NaCl 添加量的增加,淀粉凝胶强度和弹性模量呈先增大后减小的趋势,凝胶弹性则呈减小的趋势;在pH4.0～7.2范围内,淀粉3 种凝胶力学性能变化趋势与不同NaCl 浓度下的变化相反;3 种糖类物质均可提高莲子淀粉的凝胶强度,其大小顺序依次为果糖＞葡萄糖＞蔗糖,同时也可提高莲子淀粉的凝胶弹性和弹性模量,但影响程度不大;当吐温-80 加入量小于0.5% 时,淀粉凝胶强度和弹性模量迅速减小,凝胶弹性略有增加,当吐温-80 加入量大于0.5% 时,淀粉凝胶力学性能基本不变。     

湿热-蒸煮处理对板栗淀粉-多酚复合物消化和回生性能的影响

该研究利用湿热-蒸煮处理制备板栗淀粉-多酚复合物，系统考察了在湿热-蒸煮处理条件下，多酚复合作用对板栗淀粉消化及回生性能的影响规律。结果显示，湿热处理可以显著提高板栗淀粉的抗消化性能，但会促进板栗淀粉的回生性能。而湿热-蒸煮处理过程中，多酚（绿原酸/咖啡酸）的添加能进一步提高淀粉的抗消化性能（抗消化成分含量：淀粉-绿原酸复合物6.77%；淀粉-咖啡酸复合物7.61%）；同时在回生过程中多酚可以有效抑制淀粉长程有序结晶和聚集态结构的形成，从而降低板栗淀粉的回生（抗回生率：淀粉-绿原酸复合物16.25%；淀粉-咖啡酸复合物22.99%）。其中相对于绿原酸，咖啡酸对板栗淀粉的抗消化性能及抑制其回生的效果更为显著。此外，相对于高水分含量（90%）体系，60%水分含量蒸煮处理后的所有板栗淀粉-多酚复合物的抗消化性能和抗回生程度均更高。研究结果将为获得更长货架期的新型高品质板栗淀粉基营养健康食品提供基础数据及理论支撑。     

EFFECT OF SUGARS ON THE THERMAL AND RETROGRADATION PROPERTIES OF OAT STARCHES

The thermal and retrogradation properties of oat starches from two cultivars (NO 753-2 and AC Stewart) were characterized in the presence of glucose, fructose and sucrose at a concentration of 36% w/v. In both oat starches, amylose leaching (AML) and swelling factor (SF) decreased in the presence of sugars (sucrose > glucose > fructose). These decreases were more pronounced in AC Stewart starch. The decrease in AML showed that sugars interact with amylose chains within the amorphous regions of the starch granule. The gelatinization transition temperature and the enthalpy of gelatinization increased in the presence of sugars (sucrose > glucose > fructose). The above increase was also more pronounced in AC Stewart starch. The decrease in SF and the increase in gelatinization parameters indicated that these changes were influenced by the interplay of factors such as starch-sugar interaction, changes in water structure in the presence of sugars, and the antiplastizing properties of sugars relative to water. The retrogradation enthalpy and the X-ray diffraction intensities of NO 753-2 and AC Stewart starch gels (stored at 4C) increased in the presence of sugars (glucose > fructose > sucrose). These changes were more pronounced in NO 753-2 starch. The results showed that interaction (during storage) between leached amylopectin and sugar molecules was the main causative factor influencing oat starch retrogradation.     

莲子淀粉重组米制备工艺优化

以不同比例莲子淀粉与碎米粉进行混合后挤压制备重组米,通过对混合粉的糊化特性和重组米的感官品质、质构特性及蒸煮损失率的分析,确定了莲子淀粉重组米的配比。以物料含水量、模头温度、螺杆转速为影响因素,采用响应面试验优化了莲子淀粉重组米挤压的最佳工艺条件。结果表明:随着莲子淀粉添加量的增加,混合粉的峰值黏度、谷值黏度、崩解值、最终黏度及回生值等均逐渐增加;感官评分先增大后减小,在莲子淀粉添加量为30%时较高;质构特性中硬度逐渐增大,弹性、咀嚼性、黏聚性先增大后减小,在莲子淀粉添加量为30%时最大;蒸煮损失率逐渐增大。综合分析,重组米品质在莲子淀粉添加量为30%时达到最佳。重组米的最佳挤压条件为:物料含水量40%、螺杆转速210 r/min、模头温度95 ℃时,重组米评分为69.13分。     

pH对莲子淀粉糊化特性影响的研究

为探讨pH对莲子淀粉糊化特性的影响,研究采用快速黏度分析仪、流变仪和差示扫描量热仪,测定不同pH条件下莲子淀粉的糊化特性、流变特性和热力学特性,并进行不等温动力学分析。结果表明:莲子淀粉糊黏度随着pH的升高呈现先增大后减小的趋势,强酸性条件热稳定性较差,碱性条件下热稳定性较强。不同pH体系条件下的淀粉糊均为非牛顿流体,具有假塑性流体特征,pH不会改变淀粉糊的流体类型。通过Power law方程对其流变特性曲线进行拟合,各样本均为剪切稀化现象,所形成凝胶为弱凝胶,体系以黏性为主。在pH5时,莲子淀粉糊具有较明显的触变性。莲子淀粉的热焓值、峰值温度、终止温度、糊化温度随着pH的升高呈现出先增大后减小的趋势,在强酸条件下,淀粉发生酸化,糊化进程及回生进程变缓;由不等温动力学得出:pH5时为莲子淀粉糊化最佳酸碱度。研究结果为莲子淀粉的综合开发利用提供了一定的理论依据。     

两种分子量的海藻酸钠对高直链玉米淀粉物化性质的影响

为探讨海藻酸钠及其分子量(AGNa)对高直链玉米淀粉(HACS)物化性质的影响,采用快速黏度分析仪(RVA)、差示扫描量热仪(DSC)、动态流变仪、物性测定仪(TA)等,研究了不同分子量的海藻酸钠-高直链玉米淀粉复合体系(AGNa-HACS)的糊化、凝胶及老化性质。结果表明,随着AGNa分子量的增加,其本身的黏度与亲水的能力增加,导致AGNa-HACS的稠度增加。分子量较低的AGNa易与HACS发生相互作用,使HACS糊化能耗增加,抑制HACS的短期老化。分子量较高的AGNa对HACS的增稠作用更为显著,有利于维持HACS淀粉糊的均一稳定,提高HACS的热稳定性,抑制HACS的长期老化。     

Functional group changes and chemical bond-dependent dielectric properties of lotus seed flour with microwave vacuum drying

Microwave vacuum drying (MVD) was applied to dehydrate lotus (Nelumbo nucifera Gaertn.) seeds. This paper evaluated the changes of molecular, crystalline, and morphological structural properties of lotus seeds after MVD. The results showed the frequency of δ(CH) bending, β(CH), ν(OH), and carbon–oxygen double bonds (C = O) increased with increasing microwave power density. Moreover, as microwave power density increased, the transition enthalpy of crystallinity gradually increased, which was related to the formation of crystalline starch, re-crystallization, and complexes of starch–lipid structure depending on the hydrogen bonds formed. The MVD process resulted molecular polarity of lotus seeds, whereas the dielectric properties also changed. The dielectric properties interacted with the changes of molecules and crystalline structure. The morphology of lotus seed flour changed because the shape of starch granules was disrupted and the granules became aggregated with nonstarch components as the microwave power density increased. All these results explain the interactions among polymer molecules in lotus seeds dried by MVD.     

纯种发酵对小米淀粉分子结构及老化特性的影响

利用自然发酵液中对淀粉老化特性起主要作用的菌种发酵,研究发酵对小米淀粉分子结构及老化特性的影响。采用0.2 g/100 m L的NaOH溶液提取发酵后的小米淀粉,研究不同菌种发酵后对小米淀粉颗粒特性、官能团、分子质量、糊化及老化特性的影响。结果表明:发酵未改变淀粉的偏光十字;植物乳杆菌、戊糖片球菌和屎肠球菌发酵后小米淀粉表面被侵蚀,酿酒酵母及芽孢菌发酵后淀粉颗粒表面侵蚀迹象变重,孔道加深且数量增多;酿酒酵母及芽孢菌发酵后小米淀粉官能团区的峰位未变,但特征峰强度减弱,植物乳杆菌、戊糖片球菌及屎肠球菌发酵后小米淀粉指纹区图谱部分消失;植物乳杆菌发酵后Ⅰ区、Ⅱ区的重均、数均分子质量较小米淀粉降低。戊糖片球菌、屎肠球菌、酿酒酵母发酵后Ⅰ区的重均分子质量升高,数均分子质量降低,Ⅱ区重均、数均分子质量降低。芽孢菌发酵后Ⅰ区的数均分子质量略有升高,Ⅱ区重均、数均分子质量降低。植物乳杆菌、戊糖片球菌及屎肠球菌发酵后淀粉的糊化温度、回生值及最终黏度降低,热焓值升高。酿酒酵母发酵后糊化温度及回生值降低,最终黏度及热焓值升高。发酵使淀粉的分子结构、支链淀粉及直链淀粉分子发生改变,短期抗老化性能提高。     

洪泽湖野生红莲子、芡实、菱角中淀粉的理化性质研究

以洪泽湖野生的红莲子、芡实、菱角为原料,采用浸泡法制备3种淀粉,并对3种淀粉的颗粒形貌、大小、结晶结构、热学性质、溶解度、膨胀度、糊化特性、分子大小与分布进行研究。结果表明:野生莲子、芡实和菱角淀粉体积平均粒径分别为11.77,2.15,25.76μm,且颗粒大小均匀。3种淀粉均为A型结晶构型,莲子、芡实和菱角淀粉的晶体度分别为27.1%,23.7%,25.7%。糊化峰值温度分别为76.04,72.37,75.88℃,糊化焓值分别为8.46,5.58,4.63J/g。3种淀粉糊的冻融稳定性较差,易形成局部的微晶束,易凝沉、易回生,均不适合应用于冷冻食品;3种淀粉糊的透明度介于马铃薯淀粉和玉米淀粉之间;3种淀粉的热糊稳定性较好,适用于高温食品的生产。     

Sulphated and carboxymethylated polysaccharides from Lycium barbarum L. leaves suppress the gelatinisation,retrogradation and digestibility of potato starch

Processing starch with polysaccharides promotes broader applications, and it is important to consider all possible structural interactions among the molecular ingredients. In this study, polysaccharides isolated from Lycium barbarum L. were chemically modified by sulphation (SLP) and carboxymethylation (CLP), and the effects on the gelatinisation, retrogradation, and digestibility properties of the potato starch were investigated. After chemical modification, the slope of the curve between the molar mass and molecular radius of polysaccharides decreased, revealing that the relatively rigid rod-like structure of native polysaccharide (0.78) changed to SLP's random linear chain (0.53) and CLP's spherical conformation (0.23), and the water solubility increased from 63.6% to 70.4% (SLP) and 84.1% (CLP) in distilled water at 25 °C. Moreover, testing polysaccharides as an additive indicated that both derivatives significantly decreased the peak viscosity, breakdown, and setback viscosity during potato starch pasting. Furthermore, the possible interactions could be further examined by structure analyses, suggesting the polysaccharide and SLP hydrogen bonds interacted with the surfaces of starch granules, while CLP penetrated the interiors of pasted starch granules, destroyed the helixes and backbone structure of starch, and formed type V crystallinity with amylose. The results of in vitro digestion analysis revealed that polysaccharides could decrease the amount of resistant starch and increase the amount of slowly digestible starch, which might be related to the inhibition of starch gelatinisation. These results facilitate the application of chemical derivatives in starch-based functional foods and understand the interaction mechanism between potato starch and polysaccharides.     

Effects of some anionic polysaccharides on the gelatinization and retrogradation behaviors of wheat starch: Soybean-soluble polysaccharide and gum arabic

Gelatinization and retrogradation behaviors of wheat starch were investigated in an aqueous system in the presence or absence of some anionic polysaccharides, soybean-soluble polysaccharide (SSPS), and gum arabic (GA). Weight-average molecular weight was almost equivalent between SSPS and GA, while z-average root-mean-square radius of gyration of GA was ca. twice as large as that of SSPS. The addition of each polysaccharide (0.1–1 w/v%) decreased the peak viscosity of the composite system (starch concentration: 5% or 13%) during gelatinization, and this effect of SSPS was greater than that of GA at the higher starch concentration. It also shifted the onset of viscosity increase to lower temperatures at the higher starch concentration, but no difference was seen in this effect between SSPS and GA. The addition of each polysaccharide (0.1–1%) decreased the amount of amylose leached during gelatinization, and this effect of SSPS was generally greater than that of GA. It hardly altered, on the other hand, the average particle diameter of the starch granules after gelatinization. “Starch ghosts” were less frequently observed microscopically in the presence of each polysaccharide, which appeared to exist around the surface of the starch granules to inhibit amylose leaching. The addition of each polysaccharide (0.5%) increased the rate constants, representing short-term (24 h) retrogradation of starch (5%). It also decreased the saturated dynamic storage modulus of the composite system after storage at 4 °C for 24 h, and this effect of SSPS was greater than that of GA with larger amount of syneresis generated. The results were discussed mainly in relation to the phase arrangement between starch components and each polysaccharide.