空心面品质评价方法的研究

以实验室制作的5种手工空心面为研究对象,用质构仪和色差仪分别测定面条的质构指标和色泽指标分析了空心面质构指标、色泽指标与感官指标之间的相关关系,建立了质构、色泽指标与感官指标的逐步回归模型。结果表明:质构仪的9个测量指标最大剪切力、韧性、硬度、黏附性、内聚性、胶着性、咀嚼性、回复性以及色差仪的3个测量指标亮度参数L*、红绿参数A*、黄蓝参数B*与感官评价所有6个单项指标以及总分都存在着极显著的相关关系。逐步回归分析发现,可以仅使用黏附性、内聚性、亮度L*和黄蓝参数B*这2个仪器测量值来代替感官评价总分。     

用色度仪和质构仪对高蛋白挂面色泽和质地的研究

用色度仪和质构仪分别测定添加不同比例脱脂大豆粉挂面的色泽和质构参数,分析了挂面的色泽参数、质构参数与面条感官评分之间的相关关系。结果显示,感官评价指标中的色泽得分与色度仪的亮度参数L!高度正相关,质构参数与感官评价指标无显著相关。分析认为,用色度仪的亮度参数L!取代感官评分中的色泽指标是可行的,质构参数中的硬度和拉伸距离与口感指标相关度较高,有重要的参考价值。     

面条的质构与感官评价的相关性研究

用质构仪分别测定市售的不同宽度、不同添加物的挂面和不同价位的油炸型方便面的质构参数,分析质构参数与面条感官评分之间的相关关系。结果表明:对于不同宽度的挂面,折断压力有助于客观评价面条的感官评价总分、适口性、韧性、光滑性;对于不同添加物的挂面,拉伸距离有助于客观评价面条的感官评价总分、色泽、表观状态;对于不同价位的油炸型方便面,最大剪切力、切割时间有助于客观评价面条的表观状态、韧性。另外,感官评价和仪器所定义的参数有一定的差别。     

米饭适口性仪器评价与其感官评价的关联性研究

米饭适口性是食味品质评价的重要指标。通过分析米饭适口性指标的仪器测定值与感官评价值,探索利用质构仪测得的质构指标代替感官评价的可行性,结果表明:质构仪测定的米饭质构指标与适口性感官评价各指标之间具有显著相关性;以各适口性感官指标为因变量,质构仪测定指标为变量建立的线性回归方程及其回归系数均达到了显著水平,回归模型预测效果较好,其感官评分值与预测值相关性最好的是弹性。     

奶糖质构性能评价方法的研究

对上海市售不同品牌奶糖的感官评定指标和质构仪测定指标进行相关性研究。研究表明,质构仪测定出的奶糖弹性、黏聚性、胶着性、咀嚼性、回复性、硬度指标与其感官评价的硬度、黏度、咀嚼性、弹性及综合评分密切相关。为利用质构仪定量表达奶糖的感官品质提供理论依据。     

凝胶软糖质构特性的感官评定与仪器分析研究

针对目前广州市场上不同品牌的凝胶软糖的质地特性进行感官评定与仪器分析的相关性研究。选用9种市售凝胶软糖,采用质地剖面检验法进行感官评定,质构仪(TPA模式)进行仪器分析,对感官评定与质构仪测定结果进行相关性分析。研究表明,凝胶软糖的仪器分析能很好地反映感官质构,其中质构仪测定出的硬度、弹性、咀嚼性与对应的感官指标有显著的相关性。选取主要仪器分析指标为自变量,感官评定指标为因变量,进行逐步回归分析,得到具有统计意义的感官硬度和感官弹性的预测方程。表明TPA质构分析和感官质构评价均能较准确地测定和反映目前市售凝胶软糖的质构。为利用质构仪测定定量表达凝胶软糖的感官质构提供理论依据。     

牛肉干感官与质构的相关性

在前期牛肉干工艺优化的基础上,对牛肉干进行感官评分和质构仪检测,探索牛肉干感官评分与质构指标之间的关系。结果表明:质构仪测试的硬度、弹性和黏聚性指标与感官评分具有极显著的相关性,由此提出以硬度、弹性和黏聚性3个质构指标来客观评价牛肉干品质,为质构仪在牛肉干品质评价的应用提供理论依据。     

湿热物理改性红小豆全粉的添加量对火腿肠质构和色度的影响

应用TA.XT2质构仪、感官评价和Hunterlab色度仪,研究了湿热物理改性红小豆全粉的添加量对火腿肠质构和色度的影响。结果表明:随着红小豆全粉的添加量增加(2%~6%),火腿肠的硬度、弹性和咀嚼性显著增加(p0.05),而火腿肠的胶粘性无明显变化;Hunterlab测定的L*值和a*值随着红小豆全粉添加量的增加而显著增加(p0.05),而b*值变化很小。感官评价的T测验结果表明,添加6.0%红小豆全粉火腿肠的风味、香气、色泽、总体接受性方面优于无添加红小豆全粉的火腿肠。     

质构仪对米饭适口性的评价研究

着重研究了利用质构仪对米饭适口性进行评价,通过相关性和回归分析建立了质构仪评价米饭适口性的回归模型,并对模型进行了验证.结果显示:质构仪所测参数值与适口性感官评价指标具有显著的相关性,以适口性感官评价各指标为因变量所建立的回归方程及回归系数达到了显著水平,平均相对预测误差值较小,且方差分析显示预测值与实测值无显著差异,这为仪器代替米饭适口性感官评价提供了理论依据.     

大米凝胶质构特性评价模型建立

采用物性仪对大米凝胶特性进行测试,对质构仪测定结果与感官评价之间的相关性进行分析,采用多元逐步回归建立了凝胶特性评价模型.结果表明,质构仪测定结果与感官评价指标具有较好的相关性,并建立了感官评定指标以压缩、剪切探头测试指标为变量的数学预测模型.采用质构仪TPA模式,以压缩和剪切探头结合的方法建立的数学预测模型可预测大米凝胶特性各指标特征值.     

Fracture Intensity Distributions during Compression of Puffed Corn Meal Extrudates: Method for Quantifying Fracturability

The distribution of fracture intensities occurring during compression of puffed corn meal extrudates was described using an exponential function, and parameters from that analysis were used as fracturability indices. Since “jagged” or oscillating stress-strain functions are typical for porous and brittle materials, fracture intensities were determined by measuring the abrupt, sequential reductions in stress produced during compression. Both distribution exponent and cumulative fracture stress correlated strongly with fracturability measured by other techniques, including fractal and Fourier analysis of stress-strain functions. Distribution parameters also indicated textural differences due to process parameters (structural modification through addition of different levels of sucrose) and storage conditions (equilibration at various relative humidities).     

A probabilistic fracture mechanics method and strength analysis of glulam beams with holes

A probabilistic fracture mechanics method is presented and applied to glulam beams with holes. The method is based on a combination of Weibull weakest link theory and a mean stress method which is a generalization of linear elastic fracture mechanics. Combining these two methods means that the global strength will be governed by both fracture energy and material strength and also that the stochastic nature of the material properties are taken into account. The probabilistic fracture mechanics method is evaluated by comparison to experimental test results. The method shows good ability to predict strength, with the exception of very small beams where the capacity is overestimated. The comparison to experimental tests deals also with other methods for strength analysis including code design methods.     

Untersuchungen zur Ermittlung der Bruchzähigkeit an Laubholz in den Rissöffnungsmodi I und II

The results of fracture toughness tests on oak and beech are presented. The results are divided into the parts: influence of moisture on fracture toughness, influence of density and annular rings. Moreover the acoustic emissions during the cracking were measured and electron microscopic photos were taken. The results of fracture toughness tests on beech wood are presented. The specimen geometry was a CTS specimen, developed by Richard. The results of fracture toughness of modus I are similar to those of CT specimen experiments. Furthermore the mixed mode results are discussed and compared to theoretical fracture envelopes.     

基于边界效应模型的玻璃纤维复合材料准脆性断裂性能分析

为解决玻璃纤维复合材料的准脆性断裂问题,基于边界效应模型,引入玻璃纤维复合材料的单层预浸料厚度作为特征复合材料单元建立解析表达式,在三点弯曲条件下测得带有浅表面刮痕试样的峰值载荷,计算得到准脆性断裂参数:抗拉强度和断裂韧性。经正态分布分析后得到断裂参数均值:抗拉强度为169.48 MPa,断裂韧性为20.34 MPa·m^1/2,在具有95%的可靠性范围内几乎覆盖了全部试验离散点。将试样参数拟合在一起,得到断裂载荷与等效面积的线性拟合曲线,结果表明:使用正态分布法和线性拟合法得到的抗拉强度吻合度较高,二者之间的误差仅为4.95%。     

聚丙烯非织造布光催化降解用壳聚糖/阿拉伯胶微胶囊的制备

以壳聚糖和阿拉伯胶为壁材,以锐铁矿型二氧化钛为芯材制备了微胶囊.该微胶囊可通过后整理方法施加到聚丙烯非织造布中,当微胶囊的壁材破裂后释放出二氧化钛,可促进聚丙烯非织造布的光降解.研究了壳聚糖的浓度、溶液pH值、搅拌速度、反应温度和复凝聚时间对微胶囊成形的影响.结果表明,当阿拉伯胶质量浓度为6％、二氧化钛质量浓度为0.8...     

The physical basis of meat texture: Observations on the fracture behaviour of cooked bovine M. Semitendinosus

The fracture behaviour of cooked strips of beef M. semitendinosus was studied by qualitative observation of the manner in which fracture occurred and by quantitative measurements of ultimate tensile strength, work of fracture and notch sensitivity. Qualitative observations showed that fracture started in the perimysial connective tissue in all test configurations used, resulting initially in the separation of intact muscle fibre bundles. The ultimate tensile strength along and across the fibres was ～-300kNm(-2) and ～-25kNm(-2), respectively. The qualitative aspects of fracture were explained on the basis of a uniaxial fibrous composite of strong muscle fibre bundles in a weak connective tissue 'matrix', with poor interfacial strength. Work of fracture through the perimysium was in the range 0·4 to 1·8kJm(-2). The difficulty in propagating fracture across the muscle fibre bundles was explained in terms of the material's complete insensitivity to notches running across the fibres. The results imply that the muscle fibre bundle is an important level of structural organisation as far as fracture is concerned and that the strength of the perimysium, or perimysium/muscle fibre bundle interface, is likely to have a major influence on the toughness of'the cooked meat.     

40Cr钢螺栓断裂分析

分析40Cr汽车发动机底座固定用六角头螺栓断裂的原因。采用断口分析、元素分析、金相分析、力学测试和氢含量测定对断裂试样进行研究,结果表明:螺栓断口附近无明显塑性变形,断面较平齐,呈亮灰色,微观断口沿晶分离,晶粒轮廓鲜明,晶面上伴有鸡爪痕,断口附近氢质量分数高达0.00180%,认为残存在螺栓中的氢造成了螺栓延迟断裂。给出氢致延迟断裂的预防措施:(1)合理安排热处理工艺,控制热处理气氛,减少渗碳。(2)增加去氢工艺,减少螺栓中的氢残留。     

包裹体作用下的人造金刚石单晶的破裂

使用Diashape形貌分析系统，通过分析晶体的透光性和纯净度对人造金刚石所含包裹体的情况进行分级。选取包裹体含量中等的金刚石晶体，一部分在静压强度仪上施压致其开裂；另一部分通过高温煅烧致其开裂。使用超声波将已开裂晶体震开，通过分析断面形貌和成分，分析包裹体致金刚石晶体破裂失效的原因。试验发现，无论是受压，还是受热，金刚石的开裂面均平行于（111）晶面。包裹体与晶体的界面是应力集中的位置，也是裂纹源。晶体受压开裂是由于包裹体与晶体的弹性模量不同；而晶体受热之后的破裂失效，则是由于膨胀系数的不同所致。