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1.
稻谷烘干过程中的水分扩散特性与品质特性 总被引：6，自引：6，他引：0
为深入研究稻谷高效均匀化烘干过程中的水分扩散与质量转变耦合特性,该文测定了玉香油粘稻谷经50、65、80℃分别烘干时的水分有效扩散系数;检测了以上3种温度分别烘干稻谷的色差、籽粒颖壳断面孔隙率与分形维数及玻璃化转变温度,考察了已烘干稻谷的含水率、硬度、爆腰率、发芽率等过程品质差异。结果表明:玉香油粘稻谷烘干过程的有效水分扩散系数为3.576×10-8e15 684/Tm2/s;随烘干温度增加,籽粒颖壳断面的孔隙率由鲜谷的0.39±0.06依次降为0.22±0.09、0.17±0.04、0.13±0.05,但烘干稻谷的分形维数、色差、玻璃化转变温度则较其鲜谷波动增加;已烘干稻谷的含水率、硬度、爆腰率、发芽率组间差异显著(P0.05)。50℃烘干稻谷的爆腰率、发芽率性能优,宜选为稻谷烘干常用工艺温度,研究结果为稻谷高效均化烘干提供了理论与基础数据参考。 相似文献
2.
糙米机械破碎力学特性试验与分析 总被引：5，自引：3，他引：2
为了研究糙米机械破碎力学特性及其与籽粒结构特性的关系。采用物性测试仪对糙米的锥刺、三点弯曲、剪切、挤压4种机械破碎力学特性进行测试与分析,并对糙米和精米的破碎力学特性(三点弯曲)进行了比较。结果表明:糙米的断裂是由于内部胚乳组织不均匀,在外力作用下首先形成内部裂纹,裂纹尖端处的应力集中又进一步促进裂纹扩展,最终导致籽粒断裂;厚度为(1.0±0.5)mm的不同样品锥刺破碎力在10N左右,各样品籽粒内部的结合力相差较小,籽粒的断裂主要与厚度及胚乳特性有关,其中三点弯曲力更能反映籽粒的破碎特性,糙米的糠层对籽粒有一定的保护作用,糙米力学特性比精米好。该文为糙米储藏加工技术参数的确定提供依据。 相似文献
3.
不同温度及含水率稻米籽粒加工过程破裂载荷分析 总被引：2，自引：1，他引：1
稻米籽粒在收获后干燥、仓储和碾米加工过程中受到不同程度压缩载荷,过大压缩载荷将造成籽粒发生破裂(爆腰),从而降低稻米整米率和经济价值。籽粒压缩破裂载荷是稻谷加工1个重要物性参数,该文从统计学角度对稻米籽粒压缩破裂载荷进行试验研究。通过机械压缩测量试验及大样本分析,得到稻米籽粒在同一温度、含水率下,其压缩破裂载荷存在统计分布特性。定义并采用稻米籽粒中值F50和大端破裂载荷F90表征稻米压缩破裂载荷;在低温低含水率(16℃,14%)时,稻米籽粒的中值F50为63 N,F90为80 N。研究了稻米加工过程两大重要工艺参数-温度和含水率对籽粒破裂载荷的影响,发现破裂载荷随温度升高而下降,随含水率下降而增大;相比温度,含水率对破裂载荷影响更大。当稻米从高温高含水率(60℃,21%)到低温低含水率(16℃,14%)时,其由橡胶态转变为玻璃态,相应地破裂载荷从35增加到80 N。统计学意义下稻米压缩破裂载荷数值接近生产实际,更能精确指导稻米加工过程优化和产品品质提高。 相似文献
4.
不同含水率对谷子籽粒压缩力学性质与摩擦特性的影响 总被引：2，自引：7，他引：2
为了探明不同含水率谷子籽粒的物理机械性质,减少谷子籽粒在播种、碾米加工及储运等过程中受到压缩载荷及摩擦而产生的机械损伤,该文针对不同含水率的谷子籽粒进行压缩力学性质与摩擦特性试验。研究了谷子籽粒的挤压破碎过程,获得不同含水率谷子籽粒的力-位移（变形）曲线,破坏力、变形量及破坏能。随着含水率升高,破坏力减小,变形量和破坏能呈现先降低后升高的变化规律。同时采用赫兹接触理论,得到谷子籽粒单向表观弹性模量和许用挤压应力,结果表明二者都随含水率升高线性降低。分别测定了谷子籽粒与钢板和铝板间的滑动摩擦系数,随含水率升高,谷子与该2种材料的摩擦系数均增大,且与铝板的摩擦系数要高于钢板。根据试验结果,分别拟合得到了压缩和摩擦力学性能指标与谷子含水率的关系方程,为谷子播种、仓储、加工等装备设计及参数优化提供了基础依据。 相似文献
5.
品种及含水率对谷子籽粒力学性质的影响 总被引：1，自引：1，他引：0
谷子籽粒群是具有黏弹性性质的生物材料,谷子加工储藏和机械收获等作业环节需考虑其黏弹性,该文研究了不同品种、不同含水率对谷子籽粒群黏弹性力学指标的影响。该试验以不同品种、不同含水率为试验因素,以谷子籽粒群的瞬时弹性模量、迟滞弹性模量、松弛时间和黏度系数为试验指标进行蠕变试验,并对试验结果进行方差分析。结果表明:谷子籽粒群的蠕变特性可由四元件Burgers模型描述,不同含水率、不同品种谷子籽粒群的蠕变参数各异。品种对谷子籽粒群的迟滞弹性模量影响显著,晋谷21号谷子籽粒群的迟滞弹性模量均值为0.609 3 MPa,显著高于张杂10号的0.522 2 MPa。含水率对谷子籽粒群的瞬时弹性模量、迟滞弹性模量和黏度系数影响均显著,均呈随含水率升高而降低的趋势,含水率为12.10%的谷子籽粒群的瞬时弹性模量0.752 6 MPa显著高于含水率为16.05%的0.613 6 MPa和20.00%的0.569 7 MPa,含水率为12.10%、16.05%、20.00%的谷子籽粒群的迟滞弹性模量分别为0.706 4、0.583 5、0.407 5 MPa,含水率为12.10%的谷子籽粒群的黏度系数1 234.7 MPa·s显著高于20.00%的796.8 MPa·s,含水率对谷子籽粒群的松弛时间影响不显著。该文通过试验研究了不同品种和不同含水率的谷子籽粒群的蠕变特性,为谷子低损收获、加工储藏及参数优化提供了理论支持。 相似文献
6.
萌动小麦的干物质损耗与品质分析 总被引：1，自引：0，他引：1
对小麦籽粒经粒径分选和重力分选后获得的试样进行萌动发芽培养试验,从培养开始(0 h)到24 h之间以一定时间间隔对不同萌动状态的小麦进行干物质损耗测定和品质分析,结果表明：干物质的损耗随着萌动时间的增加而增加;容重(比重)越小,干物质的损耗呈现增大的趋势;各萌动时间段脂肪酸值则随着萌动时间的增加而增加;萌动籽粒的粗蛋白质含量较未萌动籽粒的低;萌动前期小麦籽粒的降落数值与未萌动籽粒相比基本上没有变化,而萌动后期的降落数值下降较快,表明此时淀粉酶的活性较高。 相似文献
7.
包衣稻种物理特性的试验研究 总被引：13，自引：6，他引：7
包衣稻种的物理特性是基于包衣稻种的播种机参数设计和性能分析的基础数据。选择了西南地区广泛种植的3个杂交水稻品种（Ⅱ优838、Ⅱ优多系57和岗优22）,对其包衣稻种的容积密度、粒子密度、恢复系数和漂浮系数等物理特性进行了试验研究。按照正交试验设计原理安排试验方案,并对结果进行了方差分析,找到了影响这些特性的主要因素及因素影响的显著性度。试验结果和分析表明：稻种状态（包衣与否）对容积密度影响显著,对漂浮系数影响比较显著,对籽粒密度和恢复系数影响较小;含水率对包衣稻种的容积密度、业粒密度和漂浮系数影响显著;品种对包衣稻种的物理特性影响较小。试验研究得到了包衣稻种在不同影响因素和各因素不同水平条件下物理特性的具体数值。 相似文献
8.
不同土壤耕作模式对冬小麦籽粒品质的影响 总被引：4，自引：1，他引：4
冬小麦籽粒的品质受土壤环境影响。为了研究不同土壤耕作模式对冬小麦籽粒品质的影响，采用了5种土壤耕作模式(常规耕作秸秆不还田、常规耕作秸秆还田、旋耕秸秆还田、缺口圆盘耙耕秸秆还田、免耕秸秆覆盖)在山东龙口进行了3年田间试验，测定了冬小麦籽粒蛋白质品质、面团流变学特性和淀粉糊化特性。结果表明：少耕模式特别是旋还模式有利于改善籽粒蛋白质质量、改善面粉的加工品质，免覆模式对改变面条蒸煮品质有利。土壤耕作可改变土壤环境，但耕作方式对冬小麦品质的长期影响仍有待于进一步研究。 相似文献
9.
花岗岩崩岗红土层土体胀缩特性研究 总被引：1，自引：0，他引：1
为研究崩岗土体因水分变化而发生干湿胀缩的特性,采集福建省安溪县典型崩岗区的红土层土样,通过室内无荷膨胀试验和收缩试验,分析不同初始干密度(1.3,1.4,1.5 g/cm^3)、不同初始含水量(15%,20%,25%和30%)下土体的无荷膨胀率和线缩率。结果表明:当含水量较低时,初始干密度越大土体膨胀率也越大;当初始干密度相同时,土壤膨胀率随其初始含水率的增大而减小。当初始含水率相同时,土样膨胀率随其初始干密度的增大而增大。不同处理的土样收缩过程有一定差异,初始含水率高的土样线缩率大,土壤膨胀和收缩过程不一致,且均为不可逆过程。该研究结果在一定程度上揭示了土壤含水率和干密度与崩岗侵蚀之间的关系。 相似文献
10.
大豆籽粒的化学-力学特性灰色关联度及本构模拟 总被引：2，自引：2，他引：0
为研究大豆籽粒在不同受载情况下的力学特性,探索其化学-力学特性之间的关系,该文选择11种大豆籽粒在含水率为8.65%下对其进行化学组分、针尖压入、剪切、压缩试验,并借助Abaqus软件建立本构模型,对压缩试验过程进行模拟仿真。力学试验和模拟结果表明:所测大豆籽粒硬度为18.39~52.58 N/mm,大豆籽粒破损强度为3.65~15.32 MPa,大豆籽粒极限剪切力为12.70~52.33 N,纵轴的抗剪能力明显高于横轴;不同压缩形式和剪切方向分别对大豆籽粒破损强度和极限剪切力影响极显著;试验与仿真的载荷-变形曲线拟合良好,说明所建立的大豆本构模型能够分析研究其抗挤压特性。灰色关联度分析结果表明:与化学组分含量最为密切的力学指标是硬度与接触刚度,其中硬度与粗蛋白质、粗脂肪、粗淀粉、粗纤维含量的关联度分别为0.309 4、0.327 8、0.171 9、0.191 8,接触刚度与其关联度分别为0.220 6、0.283 7、0.186 9、0.133 4,粗蛋白质和粗脂肪含量对硬度与接触刚度的影响最大,其次是粗纤维素,粗淀粉含量。研究结果可为品质预测和品种鉴别提供新的方法和依据。 相似文献
11.
Two wheat cultivars, soft white winter wheat Yang‐mai 11 and hard white winter wheat Zheng‐mai 9023, were fractionated by kernel thickness into five sections; the fractionated wheat grains in the 2.7–3.0 mm section were separated sequentially into three fractions according to kernel specific density. Physical properties of unfractionated, fractionated, and separated wheat grains and the physicochemical properties of processed wheat flour were determined. Test weight, relative density, and whiteness of flour in the middle kernel thicknesses were maximal and those properties decreased with increasing or decreasing kernel thickness; they also decreased with decreasing kernel specific density. Extensigraph properties showed the same results. Water absorption of flour and kernel hardness increased with increasing kernel thickness and decreasing kernel specific density. The farinograph properties also were related to kernel thickness and specific density. Pasting viscosity increased with increasing kernel thickness for sections from <2.5 mm to 3.0–3.2 mm, except that the >3.2 mm section was lowest; the kernels with the lightest specific density also were lowest. Thus, the quality of wheat grains with the greatest kernel thickness was not the best, and in fact may be the worst. The quality of wheat grains with small kernel thickness and light kernel specific density generally were worst. Most physicochemical properties of unfractionated and unseparated wheat grains were accurately predicted by the weighted‐average of the different kernel thickness sections and different kernel specific density fractions, except relative density, falling number, dough development time, and pasting temperature. 相似文献
12.
Long‐grain rice cultivars Francis and Wells and hybrid XL8 Clearfield were harvested from two locations at three harvest moisture contents (HMC) in 2003. The rough rice was dried, fractionated into thin, medium, and thick fractions, and milled. Physicochemical properties of unfractionated and fractionated samples were determined. The effects of HMC and location on thickness distributions were investigated and the weighted‐average physicochemical properties of the thickness fractions were compared with those of unfractionated rice. Generally, the growing location and HMC affected kernel thickness distributions, green kernel content, fissured kernel content, and head rice yield (HRY). As kernel thickness within samples increased, amylose content increased and the protein content and α‐amylase activity decreased. Thick fractions had greater peak viscosities than medium and thin fractions. The thin, medium, and thick fraction physicochemical property weighted averages provided good predictions of most unfractionated rice sample properties. However, this approach was not entirely accurate for predicting HRY, milled rice total lipid content, and bulk density. 相似文献
13.
Long-grain rice variety Kaybonnet was milled to three degree of milling (DOM) levels in two commercial milling systems (a single-break, friction milling system and a multibreak, abrasion and friction milling system) and separated into five thickness fractions. For both milling systems, the surface lipid content (SLC) and protein content of the milled rice varied significantly across kernel thickness fractions. SLC was influenced by DOM level more than by thickness, while the protein content was influenced by thickness more than by DOM level. Particularly at the low DOM levels, the thinnest kernel fraction (<1.49 mm) had higher SLC than the other kernel fractions. Protein content decreased with increasing kernel thickness to 1.69 mm, after which it remained constant. In both milling systems, thinner kernels were milled at a greater bran removal rate as indicated by SLC differences between the low and high DOM levels. For rice milled to a given DOM level, the multibreak system produced fewer brokens than did the single-break system. 相似文献
14.
S. R. Bean O. K. Chung M. R. Tuinstra J. F. Pedersen J. Erpelding 《Cereal Chemistry》2006,83(1):108-113
The single kernel characterization system (SKCS) has been widely used in the wheat industry, and SKCS parameters have been linked to end‐use quality in wheat. The SKCS has promise as a tool for evaluating sorghum grain quality. However, the SKCS was designed to analyze wheat, which has a different kernel structure from sorghum. To gain a better understanding of the meaning of SKCS predictions for grain sorghum, individual sorghum grains were measured for length, width, thickness (diameter), and weight by laboratory methods and by the SKCS. SKCS predictions for kernel weight and thickness were highly correlated to laboratory measurements. However, SKCS predictions for kernel thickness were underestimated by ≈20%. The SKCS moisture prediction for sorghum was evaluated by tempering seven samples with varying hardness values to four moisture levels. The moisture contents predicted by SKCS were compared with a standard oven method and, while correlated, SKCS moisture predictions were less than moisture measured by air oven, especially at low moisture content. Finally, SKCS hardness values were compared with hardness measured by abrasive decortication. A moderate (r = 0.67, P < 0.001) correlation was observed between the hardness measurements. The SKCS predictions of kernel weight and diameter were highly correlated with laboratory measurement. Moisture prediction, however, was substantially lower by the SKCS than as measured by an air oven method. The SKCS should be suitable for measuring sorghum grain attributes. Further research is needed to determine how SKCS hardness predictions are correlated to milling properties of sorghum grain. 相似文献
15.
Vidal V Pons B Brunnschweiler J Handschin S Rouau X Mestres C 《Journal of agricultural and food chemistry》2007,55(2):336-346
A set of 27 rice varieties were evaluated for their morphological grain characteristics (length, width, thickness, thousand kernel weight, TKW), chemical composition (amylose, protein, and ash content) and starch properties (gelatinization temperature and enthalpy, amylose-lipid complex). In addition, cell walls were characterized by the arabinoxylan and beta-glucan contents. A rapid method for determining optimum rice cooking time was developed based on the swelling ratio; a fixed value of 2.55 gave a gelatinization level of 95% assessed by differential scanning calorimetry and translucence testing. Optimum cooking time appears positively correlated with kernel thickness and TKW but also with ash content. Confocal laser and scanning electron microscope observation of uncooked rice grains revealed different structural features (cell size) and fracture behavior: for some cultivars, the fracture showed ruptured cells, whereas for others most cells were intact. These structural differences, which may be linked to pectin content, could partly explain rice kernel cooking behavior. 相似文献
16.
Observations in 1997 indicated a significant reduction in kernel bulk density and head rice yield of rice cultivar LaGrue due to blast (Pyricularia grisea). A more detailed study on rice cultivar M202 in 1998 confirmed such observations but it also showed negative effects of blast on other physical properties of rice. Rough rice from blast‐infected panicles was drier by 7–10 percentage points and 10% thinner than rough rice from blast‐free panicles. Blast also caused incidences of chalky, unfilled, and fissured kernels that were 21, 30, and 7 percentage points higher, respectively. The effects of sheath blight (Rhizoctonia solani) on kernel thickness and moisture content of rice cultivars Cocodrie, Cypress, Drew, and LaGrue were similar to the effect of blast on M202. Sheath blight generally reduced kernel bulk density but did not significantly affect head rice yield of the cultivars in 1997 and 1998 (except in one sample of Drew). There was a general trend toward higher incidences of unfilled, chalky, and fissured kernels in sheath‐blight‐infected samples. The data indicated that blast could be a significant preharvest factor in causing high variability in physical properties as well as in reducing the milling quality of rice. Sheath blight is also a potentially significant preharvest factor in affecting these properties in situations where sheath blight pressure is high. 相似文献
17.
The effects of moisture, screw speed, and barrel temperature on pasting behavior of refabricated rice grains were investigated in a corotating twin‐screw extruder with response surface methodology. The rice flour obtained from broken rice (≤1/8 of actual kernel size) of PR‐116 variety was used in the study. The screw speed was set at five levels between 49 and 150 rpm, barrel temperature between 59 and 110°C, and feed moisture between 31 and 45%. All pasting properties of refabricated grains evaluated—peak viscosity, hold viscosity, breakdown viscosity, final viscosity, and setback viscosity—were significantly (P < 0.01) affected by the three process variables. Barrel temperature was the most significant variable, with quadratic effect on all viscosity parameters. Response surface regression models were established to correlate the viscosity profile of refabricated rice grains to the process variables. The optimum moisture content, screw speed, and barrel temperature estimated by a response surface of desirability function for the production of refabricated rice were 36%, 130 rpm, and 89.5°C, respectively. Scanning electron microscopy also revealed that intermediate moisture and temperature along with high screw speed during extrusion could create a more realistic appearance of refabricated rice with less rupture of starch granules. 相似文献
18.
Three cultivars of long-grain rice were milled to three degree of milling (DOM) levels. Inverse linear relationships were established between surface fat concentration (SFC) and Satake milling meter (MM1B) optical DOM measurement values, including whiteness, transparency, and DOM, for the unfractionated head rice within each cultivar. Milled bulk rice for each cultivar was subsequently separated into thickness fractions. Effects of milled rice kernel thickness on SFC and optical DOM measurements were investigated. For a given DOM level, SFC decreased with increasing milled rice kernel thickness up to a thickness of 1.67 mm, after which it remained constant. As the overall DOM level increased, the difference in DOM between thin kernels and thick kernels lessened, implying that thin kernels were milled at a greater bran removal rate than thick kernels. Milled rice kernel thickness significantly (at the 0.05 significance level) affected MM1B whiteness and MM1B transparency in two of the cultivars because of the predominant effects of the thinner kernel fractions. Within each cultivar, MM1B DOM was not significantly influenced by milled rice kernel thickness. 相似文献
19.
水稻秸秆冷压成型试验得到的成型燃料能耗较高且质量不佳,为提高水稻秸秆成型燃料质量,本次试验利用水稻秸秆成型设备,在不同成型压力、原料粒径、温度以及含水率等工艺参数条件下对水稻秸秆进行热压成型试验。通过分析成型燃料的物理性能,确定各工艺参数最佳选取范围为：粒径0~2mm、温度70~100℃、成型压力8.89～40MPa、含水率12%～25%。为进一步提高水稻秸秆原料成型燃料的质量,提出通过添加木质素含量较高的木屑原料即形成混合原料,并通过对比试验进行研究。结果表明,混合原料可以有效提高水稻秸秆成型燃料的综合质量。 相似文献
20.
水稻在吸湿环境中的裂纹生成研究进展及应用 总被引：10，自引：1，他引：10
当低水分的水稻暴露在可吸湿环境中就有可能产生裂纹;带有裂纹的水稻籽粒在碾磨加工中通常会断裂,从而降低整米产量。外界环境中相对湿度的变化比温度变化对裂纹生成有更大作用。水稻籽粒自身的抗裂能力与其物理性状和化学成分有关。通过改善产前产后加工技术,可以避免或减轻低水分水稻籽粒所遭受的各种潮湿环境危害,减少碎米率,提高稻米品质。 相似文献