用近红外光谱技术快速测定籼稻品种的蛋白质含量

分别以稻谷、糙米、精米和精米粉为扫描材料,应用近红外光谱法建立了籼稻蛋白质含量的预测模型.结果表明,采用光谱预处理的校正效果比不采用预处理的好,用偏最小二乘法(PLS)获得的籼稻稻谷、糙米、精米、精米粉的回归模型和交叉验证结果为:最优校正决定系数(R2)和交叉检验均方误差(RMSECv)分别为0.772 1、0.507,0.888 4、0.379,0.911 6、0.336,0.951 0、0.258,稻谷的误差最大,粉样的误差最小.育种实践中,低世代可选用糙米、高世代可选用精米和精米粉作为扫描样本测定稻米蛋白质含量.     

不同水稻品种(系)的米粉和淀粉的理化性质比较研究

以津川1号、晶香2号和F5-155的精米粉、糙米粉、精米淀粉和糙米淀粉为试验材料,分别测定各供试样品的直链淀粉含量和RVA特征谱,在50、60、70、80℃和90℃条件下测定膨胀势和水溶性指数。结果表明,同一供试材料的糙米粉与精米粉相比,最高黏度、最低黏度、崩解值、最终黏度显著下降,峰值时间没有明显差异。同一供试材料精米淀粉的最高黏度、最低黏度和最终黏度均显著高于相应的精米粉,糙米淀粉与精米淀粉相比,最高黏度均显著高于相对应的精米淀粉,糊化温度没有明显变化。供试材料精米粉的直链淀粉含量均显著高于相应的糙米粉的直链淀粉含量,精米淀粉和糙米淀粉的直链淀粉含量均显著高于相应的米粉样品。大多数供试样品的水溶性指数和膨胀势随温度的上升而显著增加。同一供试材料的4种不同样品形式中精米粉的膨胀势最高。在同一温度条件下,供试材料米粉的水溶性指数和膨胀势表现为:精米粉糙米粉;供试材料的米粉和淀粉的水溶性指数和膨胀势表现为:精米粉精米淀粉,糙米粉糙米淀粉。     

湖北籼稻品质性状和化学组成的研究

以湖北省10种不同产地籼稻为原料,分析其品质性状(糙米率、整精米率、不完善粒、垩白度、垩白率等)、食用品质和化学组成(直链淀粉、粗蛋白质、脂肪、水分等指标),研究湖北籼稻品质性状在地域上的差异。结果表明,不同产地的稻谷其化学组成和品质性状有差异;出糙率和整精米率均达到国家标准;垩白率和垩白度数值有差异;安陆稻谷样品直链淀粉质量分数18.4%～24.5%,属低直链淀粉含量,蒸煮食用品质感官评分高;不同地区样品脂肪酸值差异较大,反映了不同的贮藏品质;宣恩稻谷含有较高的硒元素含量,与其种植产地有密切关系。     

淮安稻米品质研究

采集淮安市金湖、洪泽、盱眙、涟水、淮安区、淮阴区、清浦区七个粮食主产县(区)的粳稻谷样品63份,检测了稻谷的出糙率、整精米率、垩白粒率、垩白度、直链淀粉、食味品质、胶稠度指标。结果表明,出糙率、整精米率、胶稠度、食味品质都达到国家优质粳稻谷的要求,另外87.2%的样品的垩白粒率达到国家优质粳稻谷的要求;85.7%的样品的垩白度达到国家优质粳稻谷的要求;92%的样品的直链淀粉含量达到国家优质粳稻谷的要求。     

不同加工精度对稻谷中镉含量的影响

为了解不同加工精度的稻谷中镉含量的差别,利用砻谷机、碾米机将46组稻谷分别制成糙米、四级精米、三级精米、二级精米、一级精米,三级糠粉和一级糠粉;用原子吸收分光光度计测定46组稻谷各组分的镉含量并进行分析,得出镉含量的大小顺序为:三级糠粉一级糠粉糙米四级精米三级精米二级精米一级精米;通过将稻谷中各组分两两比较进行配对样本T检验,得出一级糠粉与糙米的镉含量差异显著(P0.05),其余稻谷组分的镉含量比较分析具有较大差异性(P0.01);不同加工精度的精米中重金属镉含量也存在显著差异:四级精米镉含量最高,为(0.40±0.24) mg/kg,一级精米镉含量最低,为(0.22±0.13) mg/kg;糙米在镉限量值0.2 mg/kg范围附近时,被加工成一级精米后镉含量降低了一半左右;稻谷的糠层对镉的富集作用最强,对于整个稻米镉含量分析有较大影响。     

中国优质稻米品质的初步研究

当前,国内外评价稻米品质,着重于四个方面:碾米品质、米粒外观品质、蒸煮和食用品质以及营养品质。供试粳稻出糙率81-82％,整精米率57-62％,碾米品质优于籼稻(出糙率78-81％,整精米率57-59％)和糯稻(整精米率34-40％)。我国籼稻一般属中短粒形,长宽比小于3,但有部分品种属细长粒形。北方粳米外观品质优于南方粳米。直链淀粉含量是评价精米品质优劣的最重要指标之一。供试籼稻直链淀粉平均含量20-23％,其中59％的品种属硬胶稠度。粳稻直链淀粉平均含量18-19％,其中95％的品种属低糊化温度。直链淀粉含量与米饭硬度成正相关,而与米饭粘性和光泽成负相关。食味好的籼稻品种,一般含低直链淀粉、中到软胶稠度、中到低糊化温度。籼型稻比粳型稻的蛋白质含量高。本项研究目的在于通过对当前我国优质稻谷品质的分析,为评价现阶段我国优质米品质以及外贸部门选择出口试销品种提供重要依据,同时,为制订新的国家稻谷分级标准提供参考数据。     

基于稻谷X射线荧光光谱测定快速识别糙米和精米中的镉含量

目的 基于稻谷镉的X射线荧光光谱测定, 建立糙米、精米镉的快速定量识别模型, 简化入仓稻谷重金属检测的砻谷、碾米等预处理步骤。方法 采用X射线荧光光谱法一一对应分析26组稻谷-糙米-精米样品中镉含量。根据线性、对数、逆、二次、三次、幂、指数等函数关系分别拟合稻谷-糙米、稻谷-精米、糙米-精米镉含量之间的回归模型。采用另外4组样品对决定系数(r2)大于0.95的模型准确性进行验证, 根据决定系数、误差值等筛选最优拟合模型。结果 稻谷-糙米-精米镉含量之间存在较强的相关性, 在此基础上建立的3个可食用米镉含量快速识别模型分别为: 稻谷-糙米三次函数回归模型Y=0.0131+0.7178X+0.5722X2-0.3492X3 (R2=0.9859); 稻谷-精米三次函数回归模型Y=0.0284+0.3779X+1.5500X2-1.2046X3 (r2=0.9855); 糙米-精米幂函数回归模型Y=0.9412×X1.0233 (r2=0.9902), 三个模型预测结果的绝对误差分别为8.91%、8.57%和10.24%。结论 本研究建立的回归模型具有良好的稻米镉含量相互预测性能, 该法有望简化稻谷镉检测前的砻谷、碾米等预处理流程, 提高检测效率。     

玉米籽粒直链淀粉含量的近红外透射光谱无损检测

以214份玉米样品为材料,利用近红外谷物分析仪对样品进行光谱扫描,并测定直链淀粉含量的参比数据,借助于WinISI软件,采用多种数学处理方法和不同的回归统计方法进行定标曲线的开发,优化得到了玉米籽粒直链淀粉含量测定的近红外定标方程,其中直链淀粉占总淀粉含量及直链淀粉占样品干重两个定标方程的定标标准偏差(SEC)、定标相关系数(RSQ)、交叉验证标准误差(SECV)和检验工作标准误差(SEP)分别为2.3201和1.2064、0.8860和0.8856、2.5896和1.3769、3.368和2.133。通过内部交叉验证和外部交叉验证及对其它的231份自交系、杂交种和高直链淀粉自交系进行预测,结果表明,近红外分析技术具有较高的准确度,能代替常规化学分析方法应用于玉米育种的早代材料直链淀粉含量的筛选,可作为高直链淀粉玉米育种的一种简便快速的无损筛选技术。     

直链淀粉含量差异对糙米粉质特性影响研究

本文选取了5种直链淀粉含量差异较大的非糯糙米粉为原料,以凝胶质构特性、动态流变特性和热机械性质(Mixolab)为分析指标,比较5种不同品种糙米的粉质特性的差异性。结果显示,不同直链淀粉含量的糙米粉粉质特性差异性显著(p0.05),直链淀粉含量越高,糙米粉凝胶回复性以及流变性质最大弹性模量和粘性模量均呈增长的趋势,凝胶内聚性、糙米粉吸水率和粘度谷值逐渐减小。直链淀粉含量差异对糙米粉质特性影响较大,该研究为加工不同糙米制品原料的选取提供理论依据。     

不同加工精度对大米中镉含量的影响

将46组稻谷用砻谷机砻谷后得到糙米,再用碾米机碾去糙米的糠层,根据碾米时间的不同,将稻谷分为糙米、四级精米、三级精米、二级精米、一级精米,三级糠粉和一级糠粉;用原子吸收分光光度计测定46组大米各组分的镉含量并进行分析,得出镉含量的大小顺序为：三级糠粉>一级糠粉>糙米>四级精米>三级精米>二级精米>一级精米;通过将大米中各组分两两比较进行配对样本T检验,得出一级糠粉与糙米具有统计意义(P＜0.05),其余比较分析具有较大差异性(P＜0.01);不同加工精度的精米中重金属镉含量也存在显著差异：四级精米镉含量最高,为(0.40±0.24)mg/kg,一级精米镉含量最低,为(0.22±0.13)mg/kg;稻谷的糠层对镉的富集作用最强,对于整个稻米镉含量分析有较大影响。     

Calibration model optimization for rice cooking characteristics by near infrared reflectance spectroscopy (NIRS)

The aim of this study was to evaluate the potential of near-infrared reflectance spectroscopy (NIRS) as a rapid method to estimate the cooking characteristics of rice. A total of 586 samples from rice breeding lines from 1999 to 2002, which had high variation for agronomy, location and year, were scanned by NIRS for calibration optimization by chemometric methods. Two subsets of 212 samples from one year and 400 samples from three years were employed to find suitable sample status for extending the NIRS utilities. There were three algorithms of PCA, PL1 and PL2, in which the first one was only based on the sample spectra variant and the remaining two based on the variant of both spectra and chemical characteristics to describe the relationship between any two neighboring samples. According to the results of calibration and validation by the three algorithms used, the suitable calibration samples could be chosen by the cutoff of neighborhood distance (NH) of 0.35, 0.4 and 0.45, respectively. For the cooking characteristics, the combination of SNV+D/‘1,4,4,1’ was the best pretreatment and the accuracy models were obtained with low SECV and high 1 − VRof amylose content (1.42% and 0.95%), gel consistency (9.49 and 0.76 mm) and alkali spread value (0.86 and 0.79 grade) . The models developed using brown rice and milled rice were superior to those using intact rice grains, but slightly poorer to those using their corresponding flour samples. Therefore, on-line monitoring of rice quality could be conducted in rice processing at milling stages. Due to the fewer sample mass destroyed, the brown rice (3 g) and brown rice flour (3 g or 0.5 g), by which the NIRS models were successfully developed for cooking characteristic analyses, could be introduced into quality evaluation of germplasm and intermediate lines selection in breeding projects.     

Determination of apparent amylose content,pasting properties and gel texture of rice starch by near‐infrared spectroscopy

For breeding rice with improved quality, apparent amylose content (AAC), rapid visco analyser (RVA) pasting viscosities and gel texture properties may be routinely measured. As a direct measurement is time‐consuming and expensive, rapid predictive method based on near‐infrared spectroscopy (NIRS) is useful for measurement of these quality parameters. In this study, calibration models were developed using modified partial least‐squares regression with different mathematical treatments based on the grain and flour spectra of non‐waxy rice alone or in combination with waxy rice. The results showed that calibration models built with flour spectra are more robust than those with grain spectra, and with total rice including waxy rice are superior to those with only non‐waxy rice. Some starch quality parameters, such as AAC, setback viscosity (SB), pasting temperature (PT), hardness (HD) and cohesiveness (COH) could be predicted with sufficient accuracy by NIRS based on flour spectra, whereas only AAC and PT could be predicted with sufficient accuracy based on grain spectra. All the models reported here are usable for rough sample screening (cold paste viscosity and breakdown viscosity), sample screening (SB, PT and COH) and for most applications (AAC and HD) for routine screening of a large number of samples in the early generation selection in breeding programs. However, for accurate assay of the pasting viscosity and gel textural parameters, direct instrumental measurement should be employed in later generations. Copyright © 2007 Society of Chemical Industry     

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。     

糙米直链淀粉含量对其面包质构和体外消化性质影响研究

将不同直链淀粉含量的5种糙米磨粉,添加20%谷朊粉制作糙米面包,以比容、质构及体外消化性质为指标,研究糙米直链淀粉含量对面包品质的影响。结果表明,5种糙米直链淀粉质量分数范围在15.96%~21.88%之间。不同的糙米面包比容在2.53以上,直链淀粉质量分数大于19%时,糙米面包硬度、黏性、耐咀性显著提高。随着糙米中直链淀粉含量的增加,糙米面包淀粉体外消化率显著降低,糙米面包中抗性淀粉含量增加。直链淀粉含量19%以上的糙米制作的糙米面包品质较好。     

若干糙米及白米化学成分分析

对若干品种糙米和白米化学成分,如水分、蛋白质、脂肪酸值、粘度、不溶性直链淀粉含量等进行测定及分析,找出同品种糙米及白米化学成分特点,对糙米检测指标提供参考建议,证明糙米与白米相比在流通、储存及食用价值上具有优势。     

Development of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) on rice milling components and by-products: Effects of diet and temperature

Development of Tribolium castaneum (Herbst), the red flour beetle, was assessed on different rice components and their various by-products (i.e., diets) commonly found in rice mills, in two separate experiments. In the first experiment, eggs did not develop through to the adult stage on rough rice hulls, paddy rice dust, and milled rice dust, while eggs developed to the adult stage to some extent on rice flour, milled whole kernels, brown rice, milled broken kernels, and bran. For the diets where development occurred, the lowest percentage was on brown rice, and adults that emerged on brown rice had smaller elytra compared to adults emerging on the other diets. In the second experiment, 1–2-day old neonates were exposed on the diets listed above and held at 22, 27, 32, and 37 °C. At all temperatures, development to the pupal and adult stages was slowest on rice flour. At 22 °C, development to those stages took about twice as long compared to development at 27 °C. As temperature increased developmental times were reduced. Even though neonates developed slowest on rice flour adult emergence rates were not affected. Predictive models were used to estimate potential population development on the diets. At 22 and 27 °C, adult size as measured by elytra length was greatest when they developed on bran, while body weight was generally lowest for adults that developed on brown rice. Results show that T. castaneum can utilize rice components and by-products produced during the rice milling process, although not all components or by-products were optimal for development, and emphasis should be placed on cleaning and sanitation to remove food sources to limit infestations. Mill managers can use these results to show the importance of sanitation, and potentially improve overall pest management programs inside the mill.     

Influence of malathion resistance status on survival and growth of Tribolium castaneum (Coleoptera: Tenebrionidae), when fed on flour from insect-resistant and susceptible grain rice cultivars

The effect of insecticide resistance on the potential for control of stored product insect pests based on plant resistance was evaluated. Flours made from three rice cultivars (cvs.) that showed resistance or susceptibility to feeding by Tribolium castaneum were studied, using two strains, resistant and susceptible to the organophosphate insecticide, malathion. Flours made from rough, brown and milled rice were used to help identify the locus of any cultivar resistance mechanisms. The insect-resistant (Dawn) and moderately resistant (Lebonnet) cvs. had fewer eggs laid and caused greater mortality of the insects than the susceptible cultivar (cv.) (IR8). For all cvs., flour from brown rice was the most suitable for insect survival, whereas the highest larval weights were found in milled and the lowest in rough rice flours. On the other hand, the highest mortality of the susceptible strain occurred in milled rice flours. The larvae resistant to malathion survived significantly better than those of the susceptible strain, when fed on flour from the insect-resistant cv. (Dawn). The cause of this positive interaction between the insecticide resistance status of T. castaneum and the grain resistance is not known. The mechanism of malathion resistance occurring in this strain is enhanced malathion-specific carboxylesterase activity but it is not known how this can confer survival benefits, when the insect feeds on flour from the resistant cv. These results could have practical implications for the efficacy of stored product pest control using varietal resistance in situations where insecticide resistance is prevalent.     

Industrial-scale radio frequency treatments to control Sitophilus oryzae in rough,brown, and milled rice

Many previously studies have confirmed that radio frequency (RF) treatments have the potential to be developed as non-chemical alternative disinfestation methods. However, most of them are conducted in laboratory scale RF systems, and it is necessary to scale up the treatment protocol for industry scale applications. A pilot-scale, 27.12 MHz, 6 kW RF system was used to simulate the continuous industrial processing and finally estimate the heating efficiency and throughput for controlling adult rice weevils, Sitophilus oryzae (L.), in milled, brown, and rough rice. An electrode gap (11.5 cm) was chosen based on the appropriate heating rate (6–8 °C/min). RF heating uniformity in the three types of rice samples was improved by adding 50 °C forced hot air surface heating, sample movements on the conveyor belt at a speed of 12.5 m/h, and holding in 50 °C hot air for 6 min. The final industrial RF treatment achieved a complete mortality of adult S. oryzae and provided acceptable quality attributes in moisture content, water activity, color, protein, free fatty acid, and ash. The average heating efficiency and throughput of the RF treatments were 77.7, 76.3, and 74.3%, and 268.8, 247.3, and 224.8 kg/h for milled, brown, and rough rice, respectively. The industrial scale-up studies provide alternative physical methods for disinfesting milled, brown, and rough rice to replace chemical fumigation.     

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。     

Changes in the cadmium content of rice during the milling process

Milled rice and bran were prepared from brown rice (Oryza sativa japonica) using a commercial scale rice-mill to investigate the changes in cadmium (Cd) content caused by the milling process. Rice sample solution was prepared by microwave digestion using HNO3 and HF, then analyzed by ICP-MS. Cd was measured at m/z 114 in interference correction with MoO and Sn. The digestion method was validated with 4 kinds of certified reference material of "rice flour". We found that the Cd content was reduced only slightly by the milling process. When the Cd concentration of brown rice was regarded as 100, the relative content of the milled rice was 97 (average of 6 samples). In addition, the reduction of the Cd content was only slight when milled rice was processed to "wash-free" rice. The relative Cd content of the bran was 139 when that of brown rice was regarded as 100. These results support the hypothesis that the Cd content is not greatly decreased by the milling process.