加热糊化温度对大米淀粉中直链淀粉结晶形成的影响

采用差示扫描量热仪(DSC)研究了升降温过程中直链淀粉晶体的变化以及加热温度对大米淀粉中直链淀粉结晶形成的影响。试验结果表明:直链淀粉结晶是热可逆的,熔融后在降温过程中即可形成。对于大米淀粉(直链淀粉含量为32.6%),加热糊化的最终温度可以影响冷却过程中直链淀粉晶体的形成,糊化最终温度超过170℃后,冷却过程中才有直链淀粉的晶体形成,温度越高,形成的晶体越多。     

湖南省10种早籼稻直链淀粉含量和糊化特性的研究

取湖南省10种广泛种植的早籼稻样品,采用国标方法测定其直链淀粉含量;用快速粘度分析仪(RVA)测定其糊化特性;使用SPSS软件和PCA分析法对数据进行分析。结果表明:不同品种早籼稻的直链淀粉含量和糊化特性主要特征值均有明显差异,变异系数范围较大(0.83%~32.30%),糊化特性参数值之间互相影响。10种早籼稻直链淀粉含量的变化范围为16.12%~24.80%,依据直链淀粉含量划分了10种早籼稻的归属类型,有高含量型、中含量型和低含量型,没有出现极低含量型和糯型。采用PCA分析法把7个糊化特性参数归于2个主成分,分别为峰值粘度因子和峰值时间因子。依据这两个主成分作出主成分载荷图,实现区分不同产地的样品,以及所属直链淀粉含量类型不同的样品。      

稻米糊化温度和直链淀粉含量协同测定方法的研究

探讨了利用氢氧化钾溶液对糙米直接糊化，经标准试剂染色，在测定糊化温度的同时，利用RQS1．0系统测定直链淀粉含量的可行性。提出了一种稻米糊化温度和直链淀粉含量协同测定方法。所提出的方法具有成本低、样品用量少、快速便捷、效率高的特点，在品质改良稻米材料的快速筛选中具有良好的应用前景。     

莲藕淀粉糊化温度的测定

对莲藕糊化温度的三种测定方法展开比较,得出偏光十字消失法测得莲藕淀粉的糊化温度为63.8～71.8℃,差示扫描量热分析法(DSC)测得糊化温度为63.5～74.7℃,动态流变仪法测得糊化温度为60.1～66.2℃。得出结论:在一般的实验室里,品种相同的情况下,应用偏光十字消失法是较为准确且经济的测定方法;如果条件允许,动态流变仪法是相对精确的方法。     

莲藕淀粉糊化温度的测定

对莲藕糊化温度的三种测定方法展开比较,得出偏光十字消失法测得莲藕淀粉的糊化温度为63.8～71.8℃,差示扫描量热分析法(DSC)测得糊化温度为63.5～74.7℃,动态流变仪法测得糊化温度为60.1～66.2℃。得出结论:在一般的实验室里,品种相同的情况下,应用偏光十字消失法是较为准确且经济的测定方法;如果条件允许,动态流变仪法是相对精确的方法。      

直链淀粉含量与稻米的糊化温度及胶凝度的关系

测定了169个稻米样品的直链淀粉含量、糊化温度及胶凝度。结果表明：影响稻米蒸煮及食用品质的直链淀粉含量、糊化温度及胶凝度在一定程度上是相关的。一般直链淀粉含量低则糊化温度高而胶凝度较软。除直链淀粉含量外,其它一些因素也影响稻米的糊化温度及胶凝度。     

高直链交联变性淀粉结构及糊化性质的研究

本文采用OlympusVanoxBHS-2型多功能光学显微镜对高链及其交联变性淀粉的结构及糊化温度与pH值之间的关系进行了研究,对促进变性淀粉在生产中的应用有重要意义。     

不同乳酸菌发酵对玉米淀粉中直链淀粉含量的影响

以普通玉米淀粉为原料，研究了三种乳酸菌发酵对玉米淀粉中直链淀粉含量的影响。结果表明：三种乳酸菌发酵处理后，玉米粉中直链淀粉的含量都有不同程度的增加，并且随着发酵时间的增加，直链淀粉含量遥渐增大，达到最大值后，逐渐降低，其中嗜酸乳杆菌发酵5d处理的样品中直链淀粉含量最大，为32．69％。     

莲藕淀粉糊化温度测定方法的比较

采用三种方法对莲藕糊化温度进行测定,实验显示:偏光十字消失法测得莲藕淀粉的糊化温度为63.8～71.8℃,该法操作简便,具有较好的重现性和一定的准确性;动态流变仪法测得糊化温度为60.1～66.2℃,准确性高,重现性好,测得的糊化温度范围较小,是相对精确的方法;差示扫描量热分析法(DSC)图谱法测得糊化温度为63.5～74.7℃,温度范围相对较大,并可以较全面地反映淀粉的糊化特性。     

Properties of Lintnerized Starch Granules from Rices Differing in Amylose Content and Gelatinization Temperature

A study was made on the properties of starch granules of eight rices differing in amylose content and gelatinization temperature subjected to hydrolysis in 2.2-N HC1 at 35°C for 15 days. The recovery of lintnerized starch was greater for samples with high gelatinization temperature and, to a lesser extent, high amylose content. Lintnerized starch had sharper X-ray diffraction peaks than native starch. Their DP ranged from 18.8 to 30.3 glucose units, and the β-amylolysis limit ranged from 74.5 to 92.1%. Gel chromatography showed two peaks corresponding to DP 29–34 and 14–7. Varietal differences were noted in the ratio of the two amylodextrin peaks.     

不同品种小米的直链淀粉含量与快速黏度分析仪谱特征值关系研究

采用快速黏度分析仪(RVA)分析全国27 个小米品种的RVA 谱线和各特征值间的相关性。结果表明：小米品种间的RVA 谱特征值差异显著,小米衰减值的测定对于小米的品种鉴别具有较强的区分能力;直链淀粉含量与衰减值呈极显著负相关,与回生值呈极显著的正相关。可以利用直链淀粉含量并辅助RVA 谱特征值进行小米品质的鉴定。     

早籼配制米配方及加工技术

为改善低质早籼米品质,在分析浙江省主栽早籼基米米质基础上采用籼米之间配制技术。配方研究是以控制直链淀粉含量为核心,以长宽比相近为原则,通过调整不同直链淀粉含量品种的搭配比例,达到直链淀粉含量15%~20%且改善其早籼米饭过硬或过粘的食味特性的目的。对配方米的米质和食味的鉴定结果表明配制米米质和食味品质明显好于单一早籼基米。在配米生产工艺上采用原料搭配或成品搭配,使配米精度优于1%,混合均匀度变异系数CV≤10%。     

Effect of Amylose Content on Gelatinization,Retrogradation and Pasting Properties of Flours from Different Cultivars of Thai Rice

Presently, rice cultivars are categorized according to amylose content into three groups: low, medium and high amylose content cultivars. The correlation of amylose content with gelatinization properties, retrogradation, and pasting properties of eleven cultivars of Thai rice were investigated. Rice flour was prepared from milled rice by the wet grinding process. Onset (T_o), peak (T_p) and conclusion (T_c) temperatures of gelatinization, (determined by DSC) were found to be highly positively correlated with amylose levels. This correlation could be used for prediction of amylose content of rice flour. Low amylose starch could also be characterized by low degree of retrogradation (%R). The data obtained from RVA‐viscograms (peak viscosity, breakdown, setback, and pasting temperature) can be used only for characterization of the group of low amylose starches (waxy rice). It was demonstrated that low amylose rice starch provided the highest peak viscosity and breakdown and the lowest setback and pasting temperature among the groups investigated.     

基于中红外漫反射光谱技术测定精米中直链淀粉含量的研究

研究了基于傅里叶中红外漫反射光谱(DR-FTIR)技术结合偏最小二乘法(PLS)、主成分分析法(PCR)、经典最小二乘法(CLS)、逐步多元线性回归法(SMLR)快速测定精米中直链淀粉含量。实验选取了161个精米样品作为研究对象,通过光谱预处理,异常值剔除,波谱区间选择对模型进行了优化。结果表明:采用PLS建模,通过多元散射校正,向后区间偏最小二乘法预处理后,所构建的模型效果最优。此时,建模区间为3 800~3 500、3 100~3 000、2 900~2 400、2 300~1 300、1 000~900 cm~(-1),模型相关系数R为0.995 6,校正均方差为0.291,预测均方差为1.23;同时,实验另选了34种精米样品对模型进行了准确性验证。结果显示验证集样品的红外预测值与真实值高度相关,线性拟合方程为Y=0.994X+0.068,相关系数R为0.994 9,说明实验所开发的直链淀粉DR-FTIR模型是有效的,预测结果准确度好,模型稳定性高。     

Amylose Content and Puffed Volume of Gelatinized Rice

A total of 113 experimental and commercial rough rice consisting of 6 short, 49 medium and 58 long grain types were used to determine the role of amylose and other selected properties on the puffing characteristics of gelatinized rice. Statistical analysis of the data on head rice yield, volume, length-width ratio, moisture of gelatinized dried rice, amylose and expansion volume showed that (1) head rice negatively correlated to amylose (r = -0.48), (2) length-width ratio positively correlated to grain type (r =+0.95) and expansion (r =+0.62) and, (3) expansion positively correlated with amylose (r = 0.36).     

Amylose Content of Rice and Quality of Fermented Cake

The use of aged milled rice with an intermediate amylose content (20–25%) in the preparation of fermented rice cake yielded a steamed cake with a greater volume and an optimum softness as compared with similar cakes prepared from rice with a lower or higher amylose content. Aging of the rice decreased gas (CO₂) retention during fermentation, but improved gas retention and cake volume during steaming.     

后熟对粳米直链淀粉含量及品质特性影响的研究

粳米在贮藏过程中会发生后熟,后熟影响粳米的食用品质.通过不同的后熟条件处理粳米,测定处理前后粳米直链淀粉含量变化,并对处理前后的粳米进行品质特性测定.研究发现:高温加速后熟前后,粳米中直链淀粉和不溶性直链淀粉含量变化显著,分别由17.2%和10.4%上升至22.7%和14.2%,蒸煮膨胀率由27.2%上升至38.9%.在110 ℃后熟粳米7 h可以明显降低米粉糊化黏度,快速黏度分析仪测定糊化峰值黏度由5068 cP降为1607 cP,物性分析仪测量黏度由357.4 g·s降至163.4 g·s.     

Simplified Determination of Water-Insoluble Amylose Content of Rice

The traditional “starch-iodine blue value” of rice gives the hot-water-soluble amylose content of rice, but previous defatting is essential for its correct determination as amylose by iodine colorimetry. Since defatting of flour is laborious and time-consuming, the hot-water extract of rice flour is defatted by shaking with petroleum ether. Colour is then developed with iodine and read at 630 nm against an amylose standard. Subtracting the above value from the total amylose content gives the insoluble amylose content.