三种回生抗性淀粉对米淀粉的冻融与流变性质的影响

研究了添加锥栗、马铃薯与绿豆回生抗性淀粉(RS3)对米淀粉的冻融稳定性与流变学性质的影响。结果表明:添加锥栗、马铃薯与绿豆RS3都能显著提高米淀粉凝胶的持水率,且冻融超过3次后,其影响的差别越来越显著。随着冻融次数增多,米淀粉凝胶中不易流动水明显降低、自由水显著增加;当冻融次数相同时,添加RS3可使米淀粉凝胶中不易流动水明显增多而自由水显著减少。添加锥栗、马铃薯和绿豆RS3后,米淀粉糊的黏性模量明显增加,而弹性模量的增加更加显著。在相同剪切速率下,添加锥栗、马铃薯和绿豆RS3可以使米淀粉糊的抗剪切强度大大增强。添加相同质量浓度的锥栗、马铃薯和绿豆RS3后,米淀粉糊的稠度系数都大大升高、流体指数和滞后环面积显著减小。     

冻融循环次数对超声改性玉米淀粉凝胶特性和结构的影响

探讨经超声处理的玉米淀粉在冻融循环过程中其凝胶特性和结构的变化,以期为提升速冻淀粉基食品品质提供理论指导。利用流变仪、物性分析仪、低场强核磁共振仪、傅里叶变换红外光谱仪及X射线衍射仪,分析冻融循环次数对超声改性玉米淀粉凝胶动态流变学和质构特性的影响,并对其结构进行表征。结果表明：不同冻融循环次数下,以天然玉米淀粉作对照,超声改性玉米淀粉凝胶的析水率在第4次冻融时显著下降了5.19%(P<0.05),提高了冻融稳定性;超声改性玉米淀粉凝胶的储能模量和损耗模量降低,凝胶强度变弱;硬度在第4次冻融时显著降低了10.83%(P<0.05),直链淀粉含量下降了0.15%;超声改性玉米淀粉凝胶的碘结合力减弱,横向弛豫时间分布曲线整体左移,短程有序结构减弱,相对结晶度降低。综合凝胶特性和结构表征结果,表明超声处理能够抑制冻融循环过程中玉米淀粉凝胶体系中的水分迁移和双螺旋结构的形成,改善其冻融稳定性。     

超高压改性淀粉凝胶特性研究

以马铃薯淀粉及玉米淀粉为原料,在确定适宜淀粉乳浓度基础上,研究了超高压改性淀粉糊化特性、凝胶质构及冻融稳定性。结果显示,马铃薯淀粉较玉米淀粉更能耐受超高压,500 MPa处理会导致玉米淀粉部分糊化,而马铃薯淀粉颗粒形貌变化不大。适宜条件超高压改性有利于马铃薯淀粉及玉米淀粉形成更强的凝胶,所制备的凝胶硬度、黏性、咀嚼性较原淀粉明显增加。与玉米淀粉凝胶相比,马铃薯淀粉凝胶具有更好的冻融稳定性,超高压处理进一步增强了淀粉冻融稳定性,尤其是马铃薯淀粉经过一次冻融循环时,冻融稳定性较高。然而,淀粉部分糊化不利于形成高强度淀粉凝胶,且冻融稳定性亦变差。     

小麦淀粉凝胶冻融稳定性研究

以精制小麦淀粉(纯度为99%)为原料,研究小麦淀粉凝胶冻融稳定性。扫描电子显微镜(SEM)显示,凝胶经5次冻融循环后结构明显破损、网络空隙增大;质构仪测定凝胶的硬度和胶着性分别提高了65.9%和54.02%、弹性减低了16.8%;随冻融循环次数的增加,凝胶析水率增大了14倍;差示扫描量热仪(DSC)测定小麦淀粉凝胶冻融后老化度、冰晶熔化焓变化,结果显示凝胶经5次冻融后冰晶融化焓增大了18.05%,老化度也相应增大。     

荸荠淀粉的特性研究

荸荠淀粉是从荸荠中提取的，本文通过与马铃薯淀粉和玉米淀粉相比较，用显微镜、偏光显微镜、凝胶色谱等方法，研究了荸荠淀粉的颗粒形状和大小以及它的化学组成和淀粉分子分子量的分布，并测定了荸荠淀粉的糊化温度和成糊后的透明度和凝沉性。结果表明：荸荠淀粉的特性与玉米淀粉和马铃薯淀粉的特性有明显的不同。     

冻融循环处理对玉米淀粉凝胶结构及颗粒理化特性的影响

本文研究了不同次数(0、1、2、3、4、5和6次)的冻融处理对糊化后的普通玉米和糯玉米淀粉凝胶理化性的影响。采用扫描电子显微镜对淀粉凝胶的微观结构进行分析,测定了凝胶化淀粉的碘蓝值、碘结合力、最大吸收波长、透明度、持水性、溶解度与膨胀力、水解特性和体外消化性。普通玉米淀粉凝胶呈孔状结构,糯玉米淀粉凝胶冻融2次后出现层状结构,二者孔径和层距都随冻融次数增加而减小。冻融循环处理对两种凝胶化玉米淀粉的碘蓝值、碘结合力、最大吸收波长和直链淀粉含量均无显著性影响。随冻融次数增加,普通玉米淀粉的透明度、持水性、RDS与SDS含量逐渐减小,而溶解度、膨胀力、水解率和RS含量逐渐升高;而糯玉米淀粉的透明度、持水性、溶解度和膨胀力逐渐减小,RDS、SDS和RS含量及水解率均无显著性变化。     

马铃薯淀粉对玉米醇溶蛋白凝胶特性的影响

以马铃薯淀粉和玉米醇溶蛋白为原料制备凝胶,测定复合凝胶持水、白度、溶胀、质构和结构特性等指标,探究不同马铃薯淀粉添加量(质量分数6%、9%、12%、15%、18%)和冻融处理对玉米醇溶蛋白凝胶特性的影响。结果表明,随着马铃薯淀粉添加量的增加,复合凝胶的硬度、咀嚼性和弹性均显著增加(P<0.05),内聚性先减小后增加,冻融处理后的凝胶质构特性均得到提高;持水性呈增加的趋势,但冻融处理后的复合凝胶持水性均出现不同程度的下降;白度值显著上升(P<0.05);溶胀特性呈下降趋势;化学作用力中以氢键和疏水相互作用为主,二硫键和离子键相对较弱。因此,马铃薯淀粉的添加可以改善玉米醇溶蛋白的凝胶特性,为玉米醇溶蛋白凝胶的进一步开发应用提供一定理论依据。     

冻融循环次数对淀粉结构及理化性质影响的研究进展

冻融处理是常用的物理改性方法,在影响淀粉冻融特性的因素中,冻融循环次数是最主要的因素之一。研究发现冻融处理可以提高淀粉的吸油率,导致淀粉晶体结构发生转变,使结晶度增加,而这些变化的形态因素与冻融循环次数呈显著相关。本文总结冻融循环次数对淀粉结构特性和理化性质的影响,通过对冻融循环中淀粉结构和性质的变化为进一步研究改性淀粉提供理论依据。     

含水量对湿热处理荸荠淀粉性质的影响

为有效开发利用荸荠淀粉,以荸荠淀粉为原料,将荸荠淀粉的含水量分别调节为20%、25%、30%、35%,利用鼓风干燥烘干箱在105℃下湿热处理2 h,研究湿热处理对荸荠淀粉糊化特性、流变特性、溶解度与膨胀度的影响。结果表明:随着湿热处理淀粉含水量的增大,淀粉糊峰值黏度和衰减值均有所降低;谷值黏度有所升高,淀粉颗粒的溶解度和膨胀度均有一定程度的下降;剪切稀化现象减弱;损耗角正切值越来越小,荸荠淀粉在湿热处理后所形成的凝胶为弱凝胶。     

水分子相态转变对花桥板栗淀粉凝胶结构的影响

水分子相态转变会导致淀粉基制品的品质发生劣变,这主要是由水分子相态转变引起淀粉凝胶特性改变所致。而淀粉基食品在冻融处理过程中经常会涉及到水分子的相态转变。本文以花桥板栗淀粉为研究对象,采用SEM、XRD、FT-IR研究了水分子相态转变处理次数对花桥板栗淀粉凝胶的微观结构、晶体特性等方面的影响。结果显示,水分子相态转变使得花桥板栗淀粉凝胶结构发生失水收缩现象。随着相态转变次数增加,凝胶结构中的孔径逐渐变大并发生淀粉分子重排。水分子相态转变对其形成新的晶体结构贡献不大,后者晶体结构大多为CB型。随着相态转变处理次数的增加,结晶度从2.97%增加到了12.78%,相态转变7次后,结晶度下降为5.71%。随着相态转变的增加,羟基(-OH)发生红移;而醇羟基、C-O-C中的C-O发生蓝移且分别在转变3次、4次后峰位不发生偏移,但峰高增加。     

The effect of freeze–thaw cycles on microstructure and physicochemical properties of four starch gels

The effect of repeated freeze–thaw (FT) cycles (up to seven) on microstructure, thermal and textural properties of four starch gels from various botanical origins (gingko, Chinese water chestnut, potato and rice) was investigated and compared by scanning electronic microscope, differential scanning calorimetry and texture analyzer. The chemical composition and molecular structure of four starches were also examined. The Chinese water chestnut, potato and rice starch gels formed a honey-comb structure after 7 FT cycles, while gingko starch gel exhibited lamellar structure. The 7 FT cycles decreased the transition temperatures and enthalpies of four starches in comparison with each native starch, and the retrogradation percentage followed the order: rice > gingko > Chinese water chestnut > potato. The 7 FT cycles increased the hardness of all the evaluated starch gels and decreased springiness and cohesiveness. Results showed that the molecular structure of starches caused notable differences to the microstructure and textural properties of starch gels. The higher amount of longer branch chain (degree of polymerization (DP) > 18) might benefit the formation of the lamellar structure of gingko starch. The percentage of branch chains (DP 18–23) was negatively related with the springiness and cohesiveness of native starch gels, while the percentage of medium chains (DP 12–17) was positively related to the springiness of starch gels after 7 FT cycles.     

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.     

Antiretrogradation in Cooked Starch‐Based Product Application of Tea Polyphenols

Retrogradation in cooked starch‐based products is a significant hindrance in extending the shelf life of these products as they become progressively hard to bite over short time periods (say 1 or 2 months). In this study, the effects of tea polyphenols (TPs) on cooked amylopectin‐rich cassava starch have been investigated. Cassava starch was mixed with TPs and then gelatinized to form starch gels. The obtained gels were stored for up to 80 d and characterized by X‐ray diffraction (XRD), hardness test, color analysis, and Fourier transform infrared spectroscopy (FT‐IR). The results of XRD show that the formation of long‐range ordered structure of amylopectin was retarded by the interaction of TPs with amylopectin via hydrogen bond. The results of hardness test show that the accelerating increase in the hardness of cassava starch gel was retarded by the addition of TPs. The increase in hardness versus time can be correlated well using a single‐parameter exponential equation. The increase in hardness, variations in color, and FT‐IR spectrum of the TPs treated samples during storage with TPs were relatively small, suggesting that the retrogradation of starch is inhibited by TPs. This work presents an opportunity of antiretrogradation in the related products.     

Influence of pentosans on texture of starch gels during storage,and effects after enzyme treatment

The effects of commercial soluble (SAX) and insoluble (IAX) arabinoxylans (AX), and water extractable pentosans (WEP) from wheat doughs on texture profile analysis (TPA) of starch gels have been determined. Gels were also subjected to enzyme treatment with a amylase/pentosanase preparation, a lipase and their combination. SAX delayed starch gel aging and gave more cohesive and less elastic gels than starch, whereas IAX showed only a slight influence. With their combination the TPA of gels showed a predominant effect of SAX. The effect of enzyme addition was enhanced in presence of AX, but they did not improve the effect of AX without treatment. When WEP were used the addition of enzymes was more effective in delaying gel staling. Kinetics of aging depended on the type of AX present and the enzyme combination used to prepare the starch gels.     

Comparison of pressure treatment and heat treatment of skim milk with added starch on subsequent acid gelation of milk

Skim milk with added starch (waxy rice starch or potato starch at levels of 0-1.5 g/100 g) was either pressure-treated (500 MPa, 20 °C, 30 min) or heat-treated (80 °C, 30 min) and subsequently acidified (using glucono-δ-lactone) to form acid milk gels. In the second part of the study, the pH of the skim milk samples was adjusted from the natural condition (pH 6.64) to pH 6.5, 6.6 or 6.9 before the pressure or heat treatment and re-adjusted back to pH 6.64 after the respective treatment. The rheological properties of the samples during acidification and of the final acid gels were studied. The storage modulus, G′, of the final acid milk gels increased as more waxy rice starch was added to milk before pressure or heat treatment. However, acid milk gels made from pressure-treated milk with added potato starch did not show significant changes in the G′ of the final acid gels whereas those made from the heat-treated counterparts showed a marked increase in the final G′ as the potato starch level increased. Waxy rice starch was gelatinised in milk by both pressure treatment and heat treatment whereas potato starch was gelatinised by heat treatment only. Increasing the pH of milk before pressure or heat treatment increased the final G′ of the acid milk gel produced on subsequent acidification of the milk and the final G′ was increased further by the addition of waxy rice starch before the pressure or heat treatment.     

淀粉凝胶储藏过程中消化特性和质构特性的变化

采用酶解法和全质构分析分别测定了红薯、绿豆和马铃薯淀粉凝胶在储藏过程中的消化特性和质构特性,并对消化特性与质构特性指标之间进行简单相关和逐步回归分析。结果表明:在25℃储藏10 d内,绿豆淀粉凝胶的老化性能强于红薯淀粉和马铃薯淀粉。淀粉凝胶的消化率降低,慢消化淀粉和抗性淀粉含量增加,快消化淀粉含量降低;淀粉凝胶的硬度随储藏时间的延长逐渐增加,回复值则逐渐减小。快消化淀粉含量、硬度和回复值可作为淀粉凝胶类食品的老化评价指标。     

3D printing performance using radio frequency electromagnetic wave modified potato starch

In this study, the altered morphology, amylose content, microstructure, viscosity, and thermal properties of potato starch after being modified for different times (5, 10, 15, 20 and 30 mins) by radio frequency electromagnetic wave (RF) were studied. Obtained the most suitable RF modified time for 3D printing. The results showed that the RF treatment roughened the starch surface and reduced the amylose content, viscosity and pasting temperature of the starch. RF-treated starch gels displayed better print performance than untreated potato gels. Furthermore, RF-20 treatment offers better morphology indexes including clarity and the highest stack height, line uniformity and height retention of printed samples due to the fact that the RF treatment rearranges the internal structure of the potato starch granules, making the internal structure more stable and orderly. Overall, the RF treatment is an effective way to modify starch and optimize starch gels for 3D printing.     

Enhancement of Resistant Starch (RS3) in Amylomaize,Barley, Field Pea and Lentil Starches

Native starches isolated from amylomaize. Glacier high amylose barley, field peas and lentils contained 3–5% (w/w) resistant starch (RS3). Retrograded gels that were prepared from these starches had higher RS3 (6–9%) contents. The effects of gel concentration (% starch), storage temperature and time on the RS3 content of the retrograded gels were investigated; the optimum RS3 content was determined in gels prepared at = 10% (w/v) starch concentration and stored under = 20°C for = 5 days. Annealing of the retrograded starch gels by heating and cooling cycles, further enhanced RS3 content to 9–19%; the effect of annealing temperature and number of heat-cool cycles on the RS3 content of the annealed gel were studied. The hydrolysis of retrograded starch gels by pulanase enzyme or acid (2.2 N HCl), prior to annealing, enhanced the RS3 formation during annealing; the enzyme or acid treatment increased RS3 content of the annealed gel to 15–24% or 17–24%, respectively. The potential molecular mechanism that is responsible for the RS3 increase is discussed.     

Evaluation of the Effects of Hydrothermal Treatment on Rice Flour and Its Related Starch

The main aim of this research was to compare the effects of hydrothermal treatment on rice flour and its related rice starch. The treatment was performed at 120°C for 3 and 5 h. Scanning electron microscopy results showed that the proteins of hydrothermaled rice flour were denatured and formed clusters and the granules of hydrothermaled rice starch became aggregated and had an irregular surface. The treatment reduced water solubility and water absorption and decreased peak viscosity while increased pasting temperature. It increased the final visosity of modified rice flour while reduced the final viscosity of modified rice starch. Following hydrothermal treatment, the hardness and elasticity of the gels increased. The cohesiveness of rice flour gels decreased while that of the rice starch gels remained unchanged. This study showed how the hydrothermal treatment can have different effects on rice flour and its related rice starch. The effects of hydrothermal treatment on rice flour were stronger than rice starch. Increasing the treatment time from 3 to 5 h was more effective on rice starch.