Effect of rice bran fibre on the quality of rice pasta

This study investigated the effects of rice bran fibre (RBF) on the properties of rice pasta by extrusion processing. As the level of RBF increased, the content of total dietary fibre (TDF), insoluble dietary fibre (IDF) and soluble dietary fibre (SDF) increased, respectively. The difference in the content of ΔIDF between before and after extrusion decreased from 1.01% to 0.69% and that of ΔSDF decreased from 1.06% to 0.55%. Depending on the increasing level of RBF, the water absorption index decreased and water solubility index increased, respectively. The crystallinity of newly formed crystals decreased from 21.43% to 18.66% as the level of RBF increased. Adding RBF darkened the colour of rice pasta and reduced its hardness and chewiness. The cooking loss (CL) increased significantly compared with the control (0% RBF). The results indicate that rice pasta with extra RBF (up to 15%) can provide an acceptable quality product with a satisfactory colour and CL.     

Factor analysis of physicochemical properties of 63 rice varieties

A set of 63 Chinese‐adapted non‐waxy rice varieties of the indica and japonica subspecies was measured to extract simple indicators for rice quality evaluation. Approximate methods including amylose content (AC), gel consistency (GC), gelatinisation temperature (as measured by alkali spreading value, ASV), protein content, etc and instrumental methods including differential scanning calorimetry (DSC), viscoamylography (with a Rapid Visco‐Analyser, RVA) and texture profile analysis were adopted. Four sets of data, ie ordinary testing, flour pasting property, texture of the cooled flour gel, and visual appearance of whole milled grain and flour, were obtained and analysed for mutual relationships. Wide variations were observed in most of the measurements, eg AC (ranging from 6.3 to 28.2%), gelatinisation temperature (T_p, 65.8–83.0 °C), protein content (7.2–13.5%), pasting (peak viscosity, 92–319 RVU) and texture (hardness, 2.5–24.4 g) properties and grain appearance (grain length, 4.8–8.4 mm), to mention a few. Significant correlations were also detected among the four sets of data of the rice varieties, such as AC versus SB (setback viscosity) with a correlation coefficient of ?0.73, AC versus HRD (gel hardness) of 0.73, HRD versus FRC (gel fracturability) of 0.99, etc. Generally, the instrumental measurements including DSC, pasting and texture properties were highly correlated with the three ordinarily used indicators of rice quality, ie AC, GC and ASV. However, there was a lack of correlation between pasting properties and textural parameters, implying effects on gel texture of retrogradation of starch after cooling of the paste. Six factors were computed by principal component factor analysis that explained 80% of the variation in the traits, among which amylose content‐related (30.8%), gelatinisation temperature‐related (14.9%) and grain appearance‐related (11.1%) factors were most important. Gel pasting properties evaluated by RVA, and flour colour played less important roles in explaining total variation (accounting for a combined 23% of the eigenvalue loading). This report can be used to identify predictive parameters for rapid screening of rice genotypes for eating quality. © 2002 Society of Chemical Industry     

储藏温度对稻米淀粉糊化特性的影响

为研究稻谷储藏温度对稻米淀粉糊化特性的影响,用人工气候箱将早籼稻谷在5、15、25、35 C条件下储藏12个月.分析测定了不同温度储藏稻米淀粉的提取率、色泽、溶解度、润涨力、糊化特性及淀粉凝胶的质构特性.结果表明,相对于新收获稻米,经35℃储藏稻米提取的淀粉色泽微黄,淀粉提取率降低了19.65％;5℃储藏稻米淀粉在90℃时的膨润力最大,经储藏处理稻米淀粉在80℃和90℃的溶解度均高于新收获稻米;稻米淀粉的糊化温度和淀粉凝胶的硬度随储藏温度升高而增加,淀粉的峰值黏度和最终黏度及淀粉凝胶的黏聚性随储藏温度升高而降低.     

糙米储藏水分对糊化特性的影响

对13.5%、14.5%、15.5%、16.5%水分条件下储藏的糙米进行定期的RVA测定,糙米放入温度设定为25℃的恒温箱中储藏,储藏时间为6个月,每30d检测一次。结果表明：不同水分储藏样品的峰值粘度随着储藏时间延长不断增加,储藏水分越高,峰值粘度上升越快;水分、时间对峰值粘度影响极显著（p〈0.01）;峰值粘度与储藏时间、水分呈极显著二元线性关系。储藏样品的最低粘度随着储藏时间延长不断增加,水分含量越高最低粘度越高;水分、时间影响极显著;最低粘度与储藏时间、水分呈极显著二元线性关系。不同水分储藏样品的崩解值随着储藏时间延长变化不同;水分、时间影响显著性分别为0.029、0.000;回归方程显示,低水分储藏崩解值随着储藏时间延长而升高,高水分储藏崩解值与时间则成显著一元二次方程的关系。水分、时间对最终粘度影响显著性为0.000;最终粘度随时间、水分变化经曲线拟合呈显著二元线性关系,回归方程显著。储藏期间,糙米回生值随时间延长显著上升,储藏后期趋于下降;方差分析显示时间对回生值影响极显著,水分影响不显著,不同水分样品与储藏时间均呈极显著一元二次方程关系。含水率越高,糙米食味品质保持越好。     

Effects of germination time on the structural,physicochemical and functional properties of brown rice

Germinated brown rice (GBR) is a gluten-free food raw material. Its tissue structure, physicochemical properties and functional properties depend on the germination time. In this study, rapid viscosity analyses, differential scanning calorimetry and X-ray diffraction et al were used to analyse the structural, physicochemical and functional changes in brown rice (BR) during germination. Gamma-aminobutyric acid (GABA), total phenolic compound, glutathione (GSH) and amino acid contents increased during germination. GBR exhibited the highest GSH (22.70 mg per 100 g) and amino acid (8.02 mg per 100 g) contents at 24 h and the highest GABA content (253.35 mg per 100 g) at 36 h. Furthermore, BR germinated for 36 h showed greater enthalpy (ΔH) than ungerminated BR. Although GBR showed less crystallinity than ungerminated BR, germination did not change the crystalline structure type of starch (A-type). These results inform choices of the appropriate applications of GBR to promote its utilisation in the food industry.     

不同破碎方法对大米品质的影响

采用干法和低温润米粉碎制备大米粉,研究不同破碎方法对大米品质的影响。通过理化检测结合快速粘度分析仪、质构仪和光学显微镜测定大米粉理化指标、糊化特性、质构以及微观结构的变化。结果表明与干法粉碎相比,珍桂、双桂、桂朝和越南香米四种大米经低温润米粉碎法粉碎后大米蛋白含量从原来的6.60%、6.09%、7.06%、6.86%显著增加为7.55%、6.67%、7.58%和9.05%(p<0.05);破损淀粉含量从原来的8.2%、7.9%、8.5%和7.2%显著减小为4%、3.8%、4.3%和3.3%(p<0.05);且低温润米粉碎大米粉具有糊化温度低、崩解值小、热糊稳定性好、凝胶硬度高等相对优异的糊化和质构特性值。此外,低温润米粉碎的大米粉颗粒形态在显微镜下表面相对平整,破坏程度低。     

米粉对面团流变特性及酥性饼干品质的影响

目的 探究了米粉的添加对面团流变学特性以及酥性饼干品质的影响。方法 选取了3种米粉(粳糯米粉、籼糯米粉、普通粳米粉)分别以0%、10%、20%、30%的比例替代中筋小麦粉，研究分析了米粉-中筋小麦粉混合粉的糊化特性，面团的粉质拉伸特性，动态流变以及酥性饼干的理化性质，质构特性及感官品质。结果 随着两种糯米粉添加量增加，混合粉的糊化特征值均呈下降趋势，而添加普通粳米粉后则趋势相反；添加米粉后混合面团的吸水率和弱化度随着三种米粉的添加量的增加显著升高，分别可达65.7%和160.50，而面团形成时间和稳定时间则显著降低(P<0.05)；混合面团的弹性模量（G''），黏性模量（G"）和损耗角正切值（tanδ）随着米粉添加量的增加而逐渐减小，表明米粉的添加减弱了面筋网络的形成；与低筋粉酥性饼干相比，混合粉酥性饼干的延展比较低，且三种米粉的添加可显著提升酥性饼干的脆性，经感官评价及综合比较后得出添加20% 籼糯米粉的混合粉饼干整体品质较佳。结论 通过在中筋面粉中加入米粉后可以有效改变面团的特性，以替代低筋面粉应用于酥性饼干的加工 ，本研究也为米粉在酥性饼干专用粉的制备奠定了理论基础。     

Determination of amylopectin structure and physicochemical properties in rice endosperm starch of mutant lines derived from Malaysian rice cultivar MR219

BACKGROUND: Characterization of starch properties and functionality can apply breeding program selection for desirable traits such as eating, cooking and processing qualities to meet consumer preference. Low amylose content is generally preferred in Malaysia because of cohesive, tender and glossy cooked rice. Rice high in short‐chain amylopectin has a lower transition temperature of starch gelatinization. In the continuing search for improved starch quality in rice cultivars a study was carried out with new mutant lines MR219‐4 and MR219‐9, derived from MR219. RESULTS: MR219 and its mutant lines contain L‐type amylopectin, being high in amylopectin of intermediate chain length with degree of polymerization 12‐21. The apparent amylose content (AAC) in MR219‐4 had lower AAC value (19.2%) compared to other lines. A strongly negative correlation was found between chain‐length fraction of amylopectin and transition temperatures—onset temperature peak temperature, and conclusion temperature (0.992, 0.958, 0.950; P < 0.01)—with fraction b1 (fb1), respectively. CONCLUSION: The Malaysian lines studied contain L‐type amylopectin and offer a better understanding of grain quality improvement in terms of starch properties and functionality. This information will be directly applicable to select for desirable traits in future breeding programs. Copyright © 2012 Society of Chemical Industry     

蜡质玉米淀粉对糯米粉及速冻汤圆品质的影响

将蜡质玉米淀粉添加于糯米粉中制作速冻汤圆,考察蜡质玉米淀粉对糯米粉及速冻汤圆品质的影响.结果显示:蜡质玉米淀粉的添加能提高糯米粉的透明度,升高沉降值,同时降低糯米粉的峰值黏度和崩解值.蜡质玉米淀粉添加于糯米粉中制作速冻汤圆,使汤圆的高径比有所降低,冷冻失水率上升.加有蜡质玉米淀粉的速冻汤圆煮制后汤的透明度提高,质构特性...     

方便米饭品质特性与原料适应性的研究

精选37个品种稻米制作方便米饭,分析原料大米的成分、蒸煮品质、质构性质以及方便米饭的感官品质之间的关系。结果表明,质构仪指标中弹性与感官指标中的弹性显著正相关,咀嚼性与软硬度呈显著正相关,大米成分中的直链淀粉含量和蛋白质含量与方便米饭的软硬度有显著负相关性,与方便米饭颜色呈正相关,利用TPA实验和食味计可以快速辅助感官评价实验对方便米饭感官品质进行评价。选用直链淀粉含量低,蛋白质含量低,吸水率和体积膨胀率小的大米品种制作的方便米饭感官品质较好。      

不同直链淀粉含量大米淀粉性质的研究

以4种不同直链淀粉含量的米淀粉为原料,采用扫描电镜（SEM）、全波长自动扫描仪,质构仪等对其颗粒形貌、淀粉-碘复合物性质、ATP指标及透明度性质进行观察研究。结果表明,不同直链淀粉含量的大米淀粉颗粒形貌差异不大,均呈现不规则多边形,表面不光滑;随着直链淀粉含量的增加,淀粉颗粒的平均链长和聚合度不断增大,优糯3号淀粉颗粒内部短链数量较多,随着直链淀粉含量的增加淀粉颗粒内部的长短链比率逐渐趋近于1;淀粉糊的质构性质测定显示出淀粉糊的硬度、胶着性和咀嚼性随着直链淀粉含量的增加呈现出明显的上升趋势,弹性随着直链淀粉含量的增加变化不大,而凝胶的粘聚性明显下降;糊透明度随直链淀粉含量的增大而不断降低。      

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     

贮藏温度和时间对籼稻糊化特性的影响

研究了3种籼稻(浙富802、元隆8462与早籼5-34)在不同贮藏温度(36,25,4℃)和时间(0~3个月)下的糊化特性变化。结果表明,当贮藏温度为36℃时,贮藏时间与籼稻糊化特性显著相关(P<0.05),表现在籼稻的峰值黏度和崩解值均先上升后下降,冷糊黏度先上升后趋于稳定,回生值和糊化温度均上升,但变化时间点和程度受籼稻品种的影响。当贮藏温度为25℃时,籼稻糊化特性指标中除回生值和糊化温度未发生显著变化(P>0.05)外,其他指标的变化趋势与36℃时的基本一致,但变化时间明显滞后36℃。4℃贮藏对籼稻的糊化特性无显著影响(P>0.05)。说明,36℃可以作为籼稻加速陈化的温度,加速陈化的换算时间跟籼稻品种有关;4℃则可以作为对照组。     

原料生粉的物理性状对鲜湿切粉品质的影响

以直链淀粉和蛋白质含量差异显著的3种籼稻精米为研究材料,通过调浆(料液质量比11.5)进入产能为1 200kg/h现代机切湿米粉生产线加工成鲜湿切粉,运用扫描电镜、激光粒度仪、DSC扫描量热仪和质构仪等分析了普通干法粉碎、气流超微粉碎和水磨法粉碎的原料生粉物理性状,以及与鲜湿切粉品质的关系。结果表明,不同方法制备的精米粉体粒径大小差异显著(P<0.05),水磨粉表面光滑、呈多面体,颗粒小而均一、平均粒径5.5～7.6μm,微粉颗粒(≤15μm)占比达65.2%～79.1%,糊化焓值为6.7～7.0J/g,在现有的生产工艺条件下,原料生粉的直链淀粉含量,原料生粉在水浆中的粒径水平、粒径组成特性和分散均匀性是制约鲜湿切粉品质的关键因素;800目以上粒径的颗粒组分比例越高,鲜湿切粉品质越好,硬度10g左右、黏力0.5～0.8g、弹力0.4～0.5g可作为鲜湿切粉品质指标的重要参考;原料生粉的糊化特性、蛋白质和脂肪含量等是影响鲜湿切粉品质的次要因素。     

不同储藏时间米糠制备膳食纤维对米粉糊化和凝胶性质的影响

将米糠储藏0、1、3、5、10 d后制备的米糠不溶性膳食纤维(rice bran insoluble dietary fiber,RBIDF)添加到米粉中,研究不同储藏时间米糠制备的RBIDF对米粉糊化和凝胶性质的影响。结果表明,当RBIDF添加量相同时,随着米糠储藏时间的延长,米粉的峰值黏度呈先上升后略微下降的趋势,在米糠储藏第5天时达到最大值,回生值逐渐上升,峰值时间和糊化温度先下降后上升,分别在米糠储藏5 d和3 d达到最小值;储能模量在米粉凝胶形成阶段和米粉凝胶形成后阶段都呈上升趋势,损耗角正切在米粉凝胶形成后阶段先减小后增大,在米糠储藏5 d达到最小值;硬度、回复性、胶着性、咀嚼度先增大后减小,黏附性先减小后增大,均在米糠储藏3 d达到极值。相关性分析结果表明,米糠毛油酸值与米粉的峰值黏度呈显著(P 0. 05)正相关,与峰值时间和糊化温度呈极显著(P 0. 01)负相关,与回生值和米糠储藏时间呈极显著(P 0. 01)正相关。     

浸泡处理对早籼米糊化特性及质构特性的影响

利用快速黏度分析和质构分析方法研究浸泡处理对早籼米糊化特性和蒸煮后质构特性的影响.结果表明,当浸泡时间超过60 min时,早籼米的水分含量趋于稳定,基本保持不变;浸泡温度高,则早籼米达到饱和水分含量所需时间短,但饱和水分含量略低.经过浸泡处理后早籼米粉的热糊稳定性有明显削弱,而冷糊稳定性略有提升,幅度不大.早籼米浸泡30～60 min后蒸煮,米饭的弹性、咀嚼性和胶着性较为适宜.早籼米粉的糊化峰值黏度和黏度衰减值与米饭的硬度、胶着性及咀嚼性显著正相关,而与弹性长度显著负相关.     

复合乳化剂对糙米工程米食用品质的影响

通过测定糙米工程米熟化后米饭的分散率及其质构综合评分,研究大豆磷脂、单硬脂酸甘油酯(GMS)和蔗糖脂肪酸酯(SE)单体及其复配添加对糙米工程米食用品质的影响。结果表明:单一乳化剂对糙米工程米的食用品质有改善作用,三种乳化剂复合使用改善效果更为明显。最佳复配比例为大豆磷脂0.6%、GMS 0.2%、SE 0.5%,添加复合乳化剂糙米工程米熟化后,米饭分散率和质构特性明显改善。     

米糠膳食纤维与食盐对面粉粉质及糊化特性的影响

为了给研发高品质米糠膳食纤维面制品提供理论依据,本文用微型粉质仪和快速粘度分析仪研究了米糠膳食纤维与食盐各自及共同对面粉粉质及糊化特性的影响规律。研究结果表明:添加米糠膳食纤维使面团弱化度最高增大48%,使面粉糊化温度最大增高26%,使面粉糊化的峰值粘度最高下降23%、最终粘度最高下降21%、衰减值最高减少13%、回生值最高减少8%;添加食盐使面团的形成时间最高延长79%、稳定时间最高延长277%、弱化度最高减少52%,使面粉糊化的衰减值最高增大12%、回生值最高减少12%;添加2%食盐使米糠膳食纤维对面团弱化度的增大作用降低为0,对面粉糊化温度的最大提高作用小于2.5%,对面粉糊化峰值粘度的下降作用减少5%,对面粉糊化回生值的减小作用提高到12%。      

Salinity alters the protein composition of rice endosperm and the physicochemical properties of rice flour

BACKGROUND: Salinity is one of the major threats to production of rice and other agricultural crops worldwide. Although numerous studies have shown that salinity can severely reduce rice yield, little is known about its impact on the chemical composition, processing and sensory characteristics of rice. The objective of the current study was to investigate the effect of salinity on the pasting and textural properties of rice flour as well as on the protein content and composition of rice endosperm. RESULTS: Rice grown under saline conditions had significantly lower yields but substantially higher protein content. The increase in protein content was mainly attributed to increases in the amount of glutelin, with lesser contributions from albumin. Salinity also altered the relative proportions of the individual peptides within the glutelin fraction. Flours obtained from rice grown under saline conditions showed significantly higher pasting temperatures, but lower peak and breakdown viscosities. Rice gels prepared from the flour showed significantly higher hardness and adhesiveness values, compared to the freshwater controls. CONCLUSION: Salinity can significantly affect the pasting and textural characteristics of rice flour. Although some of the effects could be attributed to changes in protein content of the rice flour, especially the increased glutelin level, the impact of salinity on the physicochemical properties of rice is rather complex and may involve the interrelated effects of other rice components such as starch and lipids. Copyright © 2011 Society of Chemical Industry