微波对马铃薯淀粉性质的影响

研究微波辐射前后马铃薯淀粉物化性质的变化。采用微波对30%水分含量的马铃薯淀粉进行处理。结果表明:微波淀粉颗粒表面出现凹坑,降低了膨胀度和溶解度、冻溶稳定性。主要X-射线衍射峰的强度增大,晶型由B型转为A型,马铃薯淀粉经处理后糊化起始温度升高、粘度降低,粘度曲线由A型变为C型。试验表:在淀粉颗粒内无定形区和结晶区的直链淀粉与直链淀粉、直链淀粉与支链淀粉发生交互作用,微波处理使淀粉分子发生一定程度的降解。     

微波湿热处理对马铃薯抗性淀粉含量及性质的影响

在湿热条件下,采用不同微波条件对马铃薯淀粉进行处理,运用扫描电子显微镜、布拉本德粘度仪,对微波处理前后的物化性质进行了研究.结果表明,经微波辐射处理后,淀粉颗粒表面会出现小孔和凹坑;马铃薯淀粉中抗性淀粉和直链淀粉的含量、糊化转变温度及其范围、热糊稳定性和凝沉性得到提高;马铃薯淀粉的膨胀度、溶解度和粘度降低.     

微波处理对莲子淀粉理化性质的影响

为探讨微波处理对莲子淀粉的改性作用,本文利用微波工作站对莲子淀粉进行加热处理,观察预处理后的淀粉颗粒形态变化、后期糊化过程中直链淀粉溶出量和流变特性,结果表明,30%的莲子淀粉乳经不同微波功率处理后,其颗粒形态未发生明显变化,仍呈现光滑的椭球状;随着微波功率的增强,颗粒间出现了明显的聚集粘结行为,颗粒的平均粒径最大值可达26.37μm,为原淀粉2.15倍,同时淀粉颗粒晶区比例增大,995/1024吸收峰比值由0.89上升至0.99;经微波处理后的莲子淀粉,其淀粉糊的直链淀粉溶出量由120mg/g下降至87.89mg/g,淀粉糊触变性、流变粘度及弹性模量也均有降低。这说明微波处理可促使莲子淀粉拥有更紧密的晶区结构,并在后期的糊化过程中,对淀粉颗粒膨胀可能起到了一定的抑制作用,造成直链淀粉溶出量减少,从而导致淀粉糊流变特性发生变化。     

双波长法测定木薯淀粉中直链和支链淀粉的含量

目的：分离纯化木薯淀粉中的直链和支链淀粉,建立同时测定木薯淀粉中直链与支链淀粉含量的双波长法。方法：采用正丁醇结晶法分离纯化直链和支链淀粉,蓝值比较法表征直链与支链淀粉的纯度;根据双波长法原理,分别在测定波长624、538nm,参比波长440、750nm处测定木薯淀粉中直链与支链淀粉含量。结果：分离纯化得到的直链与支链淀粉蓝值分别为0.979和0.144,分别落在0.8～1.2与0.08～0.22范围内,表明纯化后木薯直链与支链淀粉的纯度较高;直链淀粉在0～80mg/L质量浓度范围内其碘复合物与吸光度呈线性关系(r＝0.9992),支链淀粉在0～220mg/L质量浓度范围内其碘复合物与吸光度呈线性关系(r＝0.9995)。结论：正丁醇结晶法能有效地分离木薯直链与支链淀粉;双波长法操作快速、准确,无需分离即可同时测定木薯淀粉样品中直链和支链淀粉含量。     

六种处理方式对慈姑淀粉理化性质的影响

为了提高慈姑淀粉的利用率，采用微波、苹果酸、盐酸、三偏磷酸钠、α-淀粉酶、乙酸酐6种不同改性方法对慈姑淀粉进行改性，并对改性后淀粉的理化特性进行了分析。结果表明：与原淀粉相比，6种处理后的慈姑淀粉均属于A型晶体结构；微波处理后的慈姑淀粉颗粒抱团成为较大颗粒，直链淀粉的相对含量增加，透明度、析水率、溶解度和膨胀度均低于原淀粉；苹果酸处理的慈姑淀粉颗粒破碎明显，透明度及膨润度降低，溶解度和直链淀粉相对含量升高；盐酸处理的慈姑淀粉颗粒出现凹坑和空洞，直链淀粉相对含量增加，凝沉性、析水率及糊化峰值温度提高，淀粉中有基团—Cl接入；三偏磷酸钠处理的慈姑淀粉颗粒出现裂纹，透明度、溶解度及膨润度降低，其糊化特性温度和焓值升高，羟基发生缔合明显；α-淀粉酶处理的慈姑淀粉颗粒表面粗糙，出现大量的凹陷，凝沉性和透明度升高，直链淀粉的相对含量降低，1 047/1 022的比值比原淀粉大，其结构更加短程有序；乙酸酐处理的慈姑淀粉颗粒表面部分出现孔洞，晶型结构没有发生改变，直链淀粉相对含量、溶解度和透明度升高，膨润度降低。综上，不同的处理方法对慈姑淀粉的理化性质影响不同，根据应用需求，可选择对应特性的改性慈姑淀...     

国产蜡质玉米淀粉糊性质的研究

主要测定国产蜡质玉米淀粉糊的基本性质。结果为，直链淀粉含量为4．95％，其溶解度略低于相同温度下鲜木薯淀粉的溶解度，与普通玉米淀粉差异不大，膨胀性较好；糊的抗凝沉、冻融稳定性比鲜木薯淀粉好，较普通玉米淀粉优越，品质比国外样品稍差；利用质构仪测定淀粉糊丝的长度，得到蜡质玉米淀粉糊丝长18．8mm；糊的Brabender粘度曲线变化与鲜木薯淀粉相似，粘度比玉米淀粉高，冷糊稳定性较好：蔗糖、食盐、硼砂对糊有增稠的作用；在中等酸性条件下，糊粘度大幅度降低，弱碱性条件下糊粘度略有增加；少量的明矾使糊粘度下降很多；单甘酯对糊粘度性质影响不大。     

微波对玉米淀粉性质影响的研究

采用微波对30％水分含量的玉米淀粉进行处理。结果表明微波处理降低了淀粉的膨胀度和溶解度、冻融稳定性以及焓值,提高了糊化转变温度、转变温度范围。玉米淀粉经处理后糊化起始温度升高、粘度降低。以上数据表明微波处理使淀粉颗粒内淀粉分子发生重排,产生了新的不同稳定性的结晶体,从而导致微波淀粉内部更加有序的结晶排列。     

硬脂酸木薯淀粉糊精的理化性质研究

本文以木薯淀粉为原料制备硬脂酸木薯淀粉糊精,研究了硬脂酸木薯淀粉糊精的理化性质。结果表明木薯淀粉经过酸解、酯化其理化性质发生了显著改变,与原淀粉相比,其溶解度、透明度、乳化性及冻融稳定性都提高,糊粘度降低。     

不同盐对木薯淀粉结构的影响

为研究不同盐对木薯淀粉结构的影响,利用LiCl、LiNO3、CaCl2和Ca(NO3)2的醇溶液处理木薯淀粉,并通过扫描电子显微镜(scanning electron microscopy,SEM)、激光共聚焦显微镜(confocal laser scanning microscopy,CLSM)、X-射线衍射仪(X-ray diffraction,XRD)、傅里叶变换红外光谱仪(fourier transform infrared spectroscopy,FTIR)以及同步热分析仪对处理淀粉进行表征,并对直链淀粉含量(amylose content,AM)进行检测。结果表明:虽然盐/醇处理后的木薯淀粉仍维持其颗粒的完整性,但其内部结构受到严重破坏。处理淀粉的晶型未受到破坏,但其相对结晶度按LiNO3、LiCl、Ca(NO3)2到CaCl2的顺序依次降低。盐/醇处理使淀粉在3424和1645cm^-1处的FTIR峰向低波数方向移动。此外,与原淀粉相比,除LiNO3处理的淀粉的直链淀粉含量增高外,其余的样品均降低。而处理淀粉的最大分解温度均低于原木薯淀粉,其降低顺序与其相对结晶度降低顺序相符。综上可知,在乙醇溶液中,不同盐对木薯淀粉结构的影响存在明显的差异性,而通过两两对比可知,Ca^2+对木薯淀粉的作用强于锂离子,而Cl^-则强于NO3^-。     

响应面法优化微波辅助酶解制备木薯抗性淀粉的工艺研究

本研究采取微波糊化辅助,普鲁兰酶酶解方法制备木薯抗性淀粉(resistant starch,RS)。以木薯RS得率为衡量指标,开展单因素试验和Box-Behnken响应面试验。验证优化试验结果证实:当木薯淀粉乳浓度值为14.5%,脱支时间为2.0 h,普鲁兰酶添加量为125.5 U/g时,可获得最大木薯RS得率值(38.31%),实测值与回归方程理论值相对偏差<1%。试验表明,采用Box-Behnken响应面法获得的优化加工工艺精确性高。根据红外谱图官能基团变化,证明制备木薯RS过程中发生了化学变化。木薯淀粉和木薯RS理化指标测定结果显示:木薯RS与木薯淀粉相比,其持水性增强,膨胀度降低,溶解度升高,直链淀粉含量增大,而冻融稳定性方面,木薯淀粉反而比木薯RS好。     

Effect of Acid‐Methanol Treatment on the Physicochemical and Structural Characteristics of Cassava and Maize Starches

Physicochemical, structural and morphological characteristics of maize and cassava starches treated with 0.36% concentrated HCl in anhydrous methanol at 54ºC for 1–8 h were analyzed and compared. Average yield of modified starch was about 97% for both starches. The solubility of the acid‐methanol treated starches increased with temperature and after 3 h of treatment reached 93% for maize starch and 97% for cassava starch at 95ºC. After 8 h of treatment, the average size of the cassava starch granules decreased from 14.9 to 11.1 µm. The action of acid‐methanol on the maize starch was more subtle, reducing the granule average size from 11.8 to 11.3 µm. Scanning electron micrographs showed that the granule surfaces were rough and exfoliated after treatment suggesting exocorrosion that was more evident for cassava starch. From GPC, it was noted that amylose and amylopectin were partially degraded during treatment. Starch crystallinity gradually increased with duration of treatment. The amylose content decreased from 21.4 to 18.8% and from 26.3 to 23.0% and the intrinsic viscosity was reduced from 2.36 to 0.21 and from 1.85 to 0.04 for cassava and maize starches, respectively. The gelatinization temperatures increased whereas pasting viscosities decreased with reaction time, especially for cassava starch. These results suggested that the attack of acid‐methanol, which was more effective on cassava starch granules, occurred preferentially in the amorphous areas located in the granule periphery and composed of amylose and amylopectin.     

不同物理方法处理对碎米中淀粉特性的影响

采用挤压、微波、超声波三种物理方法对水分含量18%的碎米淀粉进行处理,研究分析碎米淀粉经物理方法处理前后的理化性质和结构变化。结果表明,碎米淀粉经微波和超声处理后酶解力增加,糊化黏度下降,而溶解度、膨胀力、糊化温度和直链淀粉含量变化不显著;两种淀粉颗粒表面棱角减少,淀粉颗粒晶型基本没有发生变化,淀粉结晶区降低。挤压后的碎米淀粉变化较大,颗粒形状为片状,凝沉性强,1.0 h后体积仅为3 mL,糊化温度明显降低至55.0 ℃,直链淀粉含量增长为30.75%,溶解度强,为0.59%,酶解力达到45%,X-射线主要衍射峰的强度降低。     

Effects of microwave heat-moisture treatment on properties of waxy and non-waxy rice starches

Waxy and non-waxy rice starches adjusted to 20% moisture (wet basis, w.b.) were heat-moisture treated in a microwave oven to determine the effects of the microwave heating characteristics on digestibility, pasting, and morphological properties of the heated starches. Microwave heating produced only minimal changes in digestibility as well as the physical characteristics of heated starches. Significant changes in viscosity properties after microwave heat treatment were observed for both waxy and non-waxy starches heat-treated in a microwave oven, relative to non-treated samples. Non-waxy starch heated in microwave oven showed an increase in breakdown viscosity from 29.8 RVU (non-treated starch) to 35.8 RVU after heating for 60 min. However, for waxy starch, breakdown viscosity decreased from 112.7 to 35.9 RVU after 60 min of microwave heat treatment, reflecting an increased stability of microwave heat-treated starch under cooking. The data obtained in this study indicate that there was much higher re-aggregation of starch granules in waxy starch after microwave heat treatment than occurred in non-waxy starch, suggesting a re-association of amylopectin branch chains in the heat-treated waxy starch.     

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.     

不同碱对木薯淀粉结构的影响

为研究不同碱对木薯淀粉结构的影响,利用第IA主族碱金属氢氧化物配制的碱/醇溶液对木薯淀粉进行处理。通过偏振光显微镜、激光共聚焦显微镜、扫描电子显微镜、X-射线衍射分析、傅里叶变换红外光谱仪对处理木薯淀粉进行表征,并对其直链淀粉和总还原糖含量进行检测。结果表明,不同碱/醇溶液处理均不影响木薯淀粉颗粒形貌的完整性。红外结果显示没有产生新的官能团,但处理木薯淀粉在3412 cm-1处的峰向高波数方向移动,且其强度均小于原木薯淀粉。此外,随着碱金属元素所在周期的增大,碱/醇溶液处理对木薯淀粉内部结构的破坏明显增强,木薯淀粉的晶型发生变化,其相对结晶度由原来的22.03%降至15.07%,淀粉颗粒中直链淀粉含量由22.30%逐渐降低至16.51%。所有处理样品中的总还原糖含量均高于原木薯淀粉。综上可知,不同碱/醇溶液处理对木薯淀粉结构的影响表现出明显的差异。     

微波对板栗淀粉结构和理化性质的影响

为探讨微波辐照对板栗淀粉颗粒结构和理化性质的影响,采用微波辐照板栗淀粉,通过扫描电镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、差示扫描量热仪(DSC)等研究微波处理不同时间后板栗淀粉的颗粒结构和理化特性。研究表明:与原淀粉相比,微波处理后板栗淀粉的微观形貌发生明显变化,但淀粉颗粒仍为C型晶体。随着微波处理时间的增加,直链淀粉含量增大,淀粉颗粒表面出现裂纹、孔洞和黏结越显著,淀粉颗粒的相对结晶度降低、红外光谱(1 047/1 022)cm~(-1)峰强度比值降低;淀粉膨胀度和透光率也随微波处理时间的增加而降低。DSC分析表明,微波处理80 s的淀粉相转变温度(T_o和T_p)降低、糊化焓(ΔH)减少。表明微波辐照对板栗淀粉的颗粒结构和理化特征均有显著影响。     

热处理对不同直链淀粉含量的玉米淀粉理化性质的影响

采用快速黏度分析法、离心法、差示扫描量热分析法、动态流变仪分析法等,研究了干热与湿热处理对3种不同直链淀粉含量的玉米淀粉糊化性质、膨润性质、热力学性质、流变性质的影响,为淀粉的物理改性研究和加工应用提供理论依据。结果表明,干热处理使淀粉更易糊化,表现为3种玉米淀粉糊化温度降低,溶解度、膨胀度增加。湿热处理加大糊化难度,使3种玉米淀粉的糊化温度升高,膨胀度降低。热处理使玉米淀粉糊稠度、糊化焓值降低。蜡质玉米淀粉经热处理后,溶解度和老化率增加。流变性质测定结果表明,湿热处理不利于高直链玉米淀粉黏弹性凝胶的形成。     

Effect of acid treatments and drying processes on physico-chemical and functional properties of cassava starch

The effects of acid treatments (HCl or organic acids) and drying processes (oven or sun) on the physico-chemical and functional properties of cassava starch have been studied. The objective was to obtain modified starches with expansion properties similar to those of sun dried fermented cassava starch (polvilho azedo) as produced by an empirical process. Expansion was evaluated using a baking test. Independent of the drying method, organic acid-hydrolysed cassava starch presented the same X-ray diffraction patterns (changes from C to A) and similar intrinsic viscosity values. SEM observations showed no differences between granule surfaces of sun dried and oven dried samples. However sun dried organic acid-hydrolysed starches presented lower paste consistency values at 30°C when compared with oven dried ones. HCl-modified cassava starches were oven or sun dried, giving biscuits with low specific volumes (2·5–3·1 ml g⁻¹). Similar behaviour was obtained using oven dried organic acid modified cassava starches. When submitted to sun drying, organic acid modified starches showed great improvements in biscuit expansion (5–10 ml g⁻¹). The highest average specific volumes were obtained using lactic acid modified starches. © 1998 SCI.     

韧化处理对不同玉米淀粉理化特性的影响

以不同直/支链比例的普通玉米淀粉和蜡质玉米淀粉为材料,在40、50、60℃进行韧化处理,研究韧化处理对玉米淀粉理化特性的影响。结果表明：韧化处理的两种玉米淀粉颗粒形貌有较小变化。韧化处理后,两种淀粉的溶解度和膨胀度随着处理温度的升高而降低;所有韧化处理过的玉米淀粉黏度低于原淀粉,起糊温度高于原淀粉;韧化处理后淀粉的糊化温度升高,热焓变化不大。