大米糊化特性曲线探讨

本文利用Brabender淀粉粘度仪,详细研究了糯型与非糯型大米样品在特殊情况下的糊化特性,并证明有明显差别。在糊化特性曲线上发现糯米型最高粘滞峰值低于籼米型。这两种类型大米的最高粘滞峰值与它们的酶含量成负相关,与直链淀粉含量和糊化温度成正相关。     

三种大米淀粉的物性研究

以桂朝13（籼米）、武运粳7（粳米）、珍糯4130（糯米）三种大米淀粉为原料,研究比较三种类型大米淀粉的物化特性。结果表明,三种大米淀粉的碘兰值存在差异,颗粒均为较规则的多面体,且都为A型晶体;糯型淀粉相对结晶度较高,糊化温度61.9℃,易糊化,不易老化;籼型稻米淀粉糊化温度77.3℃,不易糊化,但易老化;粳型稻米处于两者之间。大米淀粉碘兰值与淀粉结晶度呈负相关性,与淀粉糊化温度、峰值黏度、回生值呈显著正相关。     

黑龙江主栽品种大米直链淀粉含量与糊化特性的研究

为研究黑龙江主产区主栽品种大米淀粉糊化特征值及其与直链淀粉的关系,以黑龙江两个大米主产区2012年种植的水稻为研究对象,采用丹麦福斯公司的近红外谷物分析仪和德国BrabenderOHG公司的Brabender淀粉粘度仪分别测定大米的直链淀粉含量和糊化特征值,运用SPSS18．0软件进行方差分析和相关性分析,比较黑龙江两个产区品种大米淀粉糊化特征值的差异及直链淀粉含量与淀粉糊化特征值间的相关性。结果表明选取黑龙江省两个主产区的大米直链淀粉含量变化范围为17．3％～18．3％．属于低直链淀粉含量;大米的最高粘度与最低粘度、崩解值呈极显著正相关,与消减值、起始糊化温度极显著负相关;最低粘度与最终粘度、崩解值呈极显著正相关,与消减值呈显著负相关;最终粘度与回复值呈极显著正相关;崩解值与消减值、起始糊化温度呈极显著负相关;消减值与回复值呈极显著正相关,与起始糊化温度呈显著正相关;大米样本中直链淀粉含量与淀粉糊化特征值相关关系均不显著。     

不同品种糙米营养品质与糊化特性分析

收集我国2013年籼型和粳型共24个品种的糙米,分析比较糙米品种间的营养品质和以糊化特性为主的加工品质的差异性。结果表明:营养品质中蛋白质、脂肪、直链淀粉、氨基酸含量、游离酚等指标品种间变异系数较大(CV15%);糊化特性中低谷黏度、最终黏度、破损值和回生值品种间差异性较大(CV15%);籼型和粳型糙米的蛋白质、直链淀粉、总淀粉的含量均影响糊化特性,且粳型糙米的糊化特性与脂肪、游离酚相关。采用聚类分析初步筛选出武运粳21(高游离酚),曲阜香稻、北旱1号(高蛋白、高赖氨酸),圣稻735(高游离酚、蛋白质和赖氨酸较高)等高营养品种。旨在为糙米育种、加工和糙米食品的开发提供基础数据。     

陈放对大米淀粉特性及米粉凝胶品质影响的研究

研究了陈放对大米直链淀粉含量、糊化值和对米粉凝胶品质的影响.研究采用9100型古物分析仪和快速粘度仪.结果表明:陈放以后,直链淀粉含量增加,支链淀粉含量减少,糊化温度会有所下降;同时陈放一定时间胶稠度变小,凝胶品质比新米更好.     

米粉(米线)原料标准的研究

本文主要对米粉所用原料大米的糊化特性、品质特性进行了分析，并且对大米的可加工性与糊化数据、直链淀粉含量之间的相关性进行了分析。结果表明：当原料中直链淀粉含量高于27％，最低粘度600～800UV，最终粘度大于1300UV，回老值高于660UV时，加工出的米粉质量较好。大米中直链淀粉含量、最低粘度、最终粘度、回老值与可加工性呈极显著相关。     

混合实验仪法对大米食用品质评价的探索研究

目的探索大米食用品质的混合实验仪(Mixolab)表征点。方法利用混合实验仪测定70种大米的相关参数,用国标法测定大米品质理化指标(蛋白质、直链淀粉含量和胶稠度),并用描述性分析法对大米进行感官评定,分析Mixolab图谱特征值与大米的理化指标以及感官评定指标之间的相关关系。结果蛋白质含量与淀粉糊化特性、淀粉热糊化胶的稳定性以及冷却阶段糊化淀粉的回生特性呈显著负相关,直链淀粉含量与吸水率呈显著负相关,与蛋白质弱化、淀粉糊化特性、淀粉热糊化胶的稳定性、冷却阶段糊化淀粉的回生特性、淀粉糊化的速度、淀粉酶的水解速度和淀粉的崩解值呈显著正相关,胶稠度与吸水率和冷却阶段糊化淀粉的回生特性呈显著正相关;感官评定质地方面的粘性、硬度和凝聚性均和Mixolab的冷却阶段糊化淀粉的回生特性值有显著相关性。结论混合试验仪法应用于大米食用品质的评价是可行的,其中冷却阶段糊化淀粉的回生特性可以作为大米食用品质评价的参考表征点。     

直链淀粉、蛋白质及脂类对大米粉热特性的影响

利用差示扫描量热仪(DSC)分别对籼米、粳米、泰国香米及糯米米粉热特性作了研究。实验结果表明:直链淀粉、蛋白质及脂类对米粉糊化熔点、峰值、糊化终点温度及糊化焓变有重要影响。直链淀粉显著影响大米米粉的糊化熔点、峰值和终点温度,高直链淀粉含量的大米米粉的糊化熔点、峰值和终点温度均高于中、低及糯米米粉;高直链淀粉含量的大米蒸煮性差、能耗高、蒸煮时间长,中、低直链淀粉含量的大米蒸煮性好、能耗少、蒸煮时间短。米粉中的蛋白质可能起到升高米粉糊化熔点、峰值及终点温度的作用;大米蛋白质含量越高,大米蒸煮性越差、能耗越高、蒸煮时间越长。米粉中的脂类对米粉热特性的影响较复杂,脂类可能起到降低糊化熔点糊化焓变的效果;大米中脂类含量越高,大米蒸煮性好、能耗少、蒸煮时间短。     

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。      

糯米与糯玉米发酵酒品质的比较

为研究糯米和糯玉米对发酵酒品质的影响,本实验选取籼糯米、粳糯米和糯玉米三种原料,测定它们的水分、蛋白质、灰分、淀粉和脂肪含量以及三种原料发酵酒的还原糖、可溶性固形物、酒精度及总酸的含量,并通过感官评定、电子舌、电子鼻进行发酵酒感官品质分析。结果表明,籼糯米、粳糯米和糯玉米中蛋白质、淀粉、脂肪含量具有显著差异（P<0.05）,糯玉米发酵酒还原糖（12.69 g/100 g）、可溶性固形物（12.89%）、酒精度（2.0%）及总酸（13.06 g/L）的含量最低,感官评分低于籼糯米、粳糯米发酵酒,但是尚在可接受范围（感官评分≥60）,显示糯玉米作为原料酿造发酵酒具有可行性。     

Gelatinization,Pasting Characteristics and Cooking Behaviour of Egyptian Rice Varieties in Relation to Amylose and Protein Contents

Gelatinization and pasting characteristics of milled powder of shortgrain rice varieties gave Amylograms which generally exhibited lower gelatinization temperatures and longer gelatinization times than long-grain varieties. Galatinization temperatures and peak viscosities were independent of amylose and protein contents; the drop in viscosity at 94 °C generally was negatively correlated with protein content but positively correlated with amylose content. The maximum volume-expansion ratio and water absorption ratio for short-grain varieties were lower than with the long-grain varieties, and the two ratios were also related to the amylose content. Apparently cooking period was the principle factor for controlling the degree of cooking.     

复配粉理化性质与米线质构性质关系的研究

将粳米粉与绿豆淀粉按照一定比例进行混合,得到粳米粉和绿豆淀粉的复配粉体系,并测定了复配粉体系的溶胀性质、糊化性质、凝胶质构性质和拉伸性质,研究了复配米粉体系的拉伸性质与米线质构性质的关系。结果表明:随着绿豆淀粉添加量比例的增加,复配米粉体系的总直链淀粉含量、可溶性直链淀粉含量和不溶性直链淀粉含量明显增加,峰值黏度、谷值黏度、末值黏度、硬度也显著性增加,咀嚼性、拉伸强度和表观弹性模量显著增加,85℃下的溶解度和膨润力显著上升;糊化温度显著降低;衰减值和回生值分别比粳米粉高了33.73 RVU和50.60 RVU;与单一体系相比,由复配粉体系制成的米线呈现较好的硬度、弹性、韧性、蒸煮性和物理性质。当绿豆淀粉∶粳米粉为1∶1时,其制得的米粉的质构性质最好。     

Effect of fertiliser on functional properties of flour from four rice varieties grown in Sri Lanka

BACKGROUND: Fertiliser is an essential agro‐chemical input in modern rice farming. Fertiliser affects the grain quality and yield of rice. Although much research has been carried out to investigate the influence of fertiliser (recommended NPK addition) on yield and quality of rice grain, little is known about the effect of fertiliser on thermal, pasting, gelling and retrogradation properties of rice flour. The aim of this study was to investigate the influence of recommended fertilisation on functional properties of rice flour from four popular high yielding rice varieties grown in Sri Lanka. RESULTS: Fertiliser (recommended NPK addition) increased the protein content but reduced the apparent amylose content in rice flour except in BG 357. Swelling power and amylose leaching of rice flour were also increased. Pasting onset temperature, cold paste viscosity and setback were increased but peak viscosity and granular breakdown decreased. In response to the fertiliser application, gelatinisation peak temperature was reduced in all varieties except BG 300. However, compared to pasting properties, gelatinisation parameters were not much affected by fertilisation. The extent of amylopectin retrogradation was decreased by fertiliser in BG 305 and BG 352 but unchanged in the other two varieties. Except in BG 305, fertiliser reduced the gel hardness of rice flour but increased the gel cohesiveness. CONCLUSION: It is apparent that the increased protein and reduced amylose content caused by fertiliser affect the functional properties of rice flour. Copyright © 2011 Society of Chemical Industry     

Pasting Properties of Ohmically Heated Rice Starch and Rice Flours

ABSTRACT:  Pasting characteristics were examined for conventionally or ohmically heated rice starch and rice flours. Brown rice flour showed the greatest cooking stability and least retrogradation potential. Brown rice flour also showed the greatest pasting temperature and lowest peak viscosity, whereas commercial starch had the lowest pasting temperature. Nonstarch components of the brown rice flour, such as fat and protein, may have acted as stabilizers delaying water access into the granules and reducing swelling of the starch. Ohmic heating reduced pasting temperature for commercial rice starch, resulting in a starch that swelled faster. Furthermore, ohmic heating produced better cooking stability in white rice flour 1 and 2 than in the native sample, and caused white rice flour 2 to have less potential for retrogradation than the conventionally heated sample. At lower electric field strength (20 V/cm), ohmic heating resulted in the greatest cooking stable starches compared to higher voltages (40 and 70 V/cm) because more starch granules were disrupted from a longer cooking time, so there were fewer intact granules for pasting. Ohmic heating has been shown to alter rice starch and flour pasting characteristics with an added influence of lipids, proteins, and amylose contents.     

Comparison of Rice Flour Pasting Properties using Brabender Viscoamylograph and Rapid Visco Analyser for Evaluating Cooked Rice Texture

Pasting properties of ten Thai rice varieties, with amylose contents in the range of 16 to 33% and stored at 10, 30 and 40 °C for six months were compared using the Brabender Viscoamylograph (VAG) and the Rapid Visco Analyser (RVA) for evaluating the texture of cooked rice. Linear correlations between pasting temperature and viscosity parameters based on RVA showed a different pattern than those based on VAG with high negative correlation coefficients between the peak and breakdown viscosities. Both RVA and VAG indicated peak viscosity to be positively correlated with breakdown viscosity, and negatively with the setback viscosity. Setback and consistency viscosities correlated with each other in both instruments but indicating a negative correlation with breakdown viscosity in VAG only. Pasting temperature determined by VAG and RVA did not show good correlations for rice sample stored at different temperatures neither for individual nor for combined data. Only peak, breakdown and setback viscosities showed significant correlations in the overall data (r > 0.496). The VAG measurements performed better than the RVA in the development of predictive models for evaluating the hardness and adhesiveness of cooked rice based on instrumental texture profile analysis. The springiness and cohesiveness of cooked rice could not be estimated from the pasting properties of rice flour determined by both VAG and RVA. Results showed that both VAG and RVA could be used for evaluating the texture of cooked rice despite the differences in the measurements of the pasting properties of milled rice flours.     

Physicochemical and Gelatinization Properties of Starches Separated from Various Rice Cultivars

Morphological, viscoelastic, hydration, pasting, and thermal properties of starches separated from 10 different rice cultivars were investigated. Upon gelatinization, the G′ values of the rice starch pastes ranged from 37.4 to 2057 Pa at 25 °C, and remarkably, the magnitude depended on the starch varieties. The rheological behavior during gelatinization upon heating brought out differences in onset in G′ and degree of steepness. The cultivar with high amylose content (Goami) showed the lowest critical strain (γ_c), whereas the cultivars with low amylose content (Boseokchal and Shinseonchal) possessed the highest γ_c. The amylose content in rice starches affected their pasting properties; the sample possessing the highest amylose content showed the highest final viscosity and setback value, whereas waxy starch samples displayed low final viscosity and setback value. The onset gelatinization temperatures of the starches from 10 rice cultivars ranged between 57.9 and 64.4 °C. The amylose content was fairly correlated to hydration and pasting properties of rice starches but did not correlate well with viscoelastic and thermal characteristics. The combined analysis of hydration, pasting, viscoelastic, and thermal data of the rice starches is useful in fully understanding their behavior and in addressing the processability for food applications.     

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.