Characterization of the flow behaviour of sausage emulsions with a simple tube viscometer

A specially designed tube viscometer was used to measure apparent viscosity during flow of Bologna type sausage emulsions moving through a pipe. Emulsions varied in fat content (from 21.8 to 44.3%) and in moisture/protein ratio (from 3.7 to 5.6), and the effects of added sodium chloride, sodium diphosphate, starch and blood plasma were investigated in a 36% fat, 3.7 moisture/protein emulsion.
The shear stresses determined as a function of shear rate were fitted by a power law. Yield stress of the emulsions was negligible relative to the applied stress. However, inspection of the flow profiles indicated that considerable slip of the sausage emulsion occurred at the pipe wall. Both emulsion flow and slip contribute to overall flow behaviour, so a kind of effective viscosity is determined. Intrinsic rheological properties and wall slip will both be affected by the composition of the sausage emulsion.     

Entrance effect correction on the flow of moisturized soy protein isolate melt in an extrusion viscometer

A newly developed capillary viscometer, having an airtight sample cell and capillary system, was utilized to determine the flow properties of moisturized [70% dry basis (d.b.)] soy protein isolate (SPI) melt at 140°C. Pressure drop measurement with an orifice die was done to clarify the large end effect. An end effect correction method was performed by subtracting the orifice die data from the capillary tube data, and reasonable results were obtained. The flow properties of the SPI melt were thus elucidated and could be classified as those of a power law fluid with flow behaviour index of 0.35. It was concluded that SPI with 70% d.b. moisture is an extremely high pseudoplastic fluid at 140°C.     

基于UDF动网格的钢索管式刮板输送机气固两相流数值研究

钢索管式刮板输送机在进行物料输送时,由于刮板的高速运动使管内形成了负压效应,空气进入和物料混合使物料呈现一定的流态化现象,有利于提高输送机的输送效率。由于刮板输送机模型的复杂性,本研究基于FLUENT中UDF动网格技术使刮板边界实现了在跑道形流道内运动的情况,成功获取了输送管内部空气相流场的运行情况,然后在此基础上进行了气固两相流的数值模拟,获得了颗粒和空气的运行参数和体积分布云图。     

A review on flow characterization methods for cereal grain‐based powders

Flow difficulties during handling, storage, and processing are common in cereal grain‐based powder industries. The many studies that focus on the flow properties of powders can be classified as flow indicators, shear properties, and dynamic flow properties. The non‐uniformity of physical and chemical characteristics of the individual particles that make up the bulk solid of cereal grain‐based powders adds complexity to the characterization of flow behavior. Even so, knowledge of flow behavior is critical to the design of productive and cost‐effective equipment for handling and processing of these powders. Because many factors influence flow, a single property/index value may not satisfactorily quantify the flow or no‐flow of powders. For powders of biological origin, chemical composition and environmental factors such as temperature and relative humidity complicate flow characterization. This review focuses on the specific flow characteristics that directly affect powder flow during handling, processing, and storage. © 2015 Society of Chemical Industry     

Non-destructive characterization and quality control of intact strawberries based on NIR spectral data

External and internal quality parameters of strawberries (Fragaria x ananassa Duch.) were studied at harvest and during postharvest refrigerated storage using a handheld micro-electro-mechanical system (MEMS) near-infrared spectrophotometer. A total of 189 strawberry punnets were used to develop calibration models using various spectral signal pretreatments and linear and non-linear regression algorithms; the sampling unit for both NIRS analysis and reference methods comprised 5 strawberries from each punnet. Modified partial least squares analysis confirmed the feasibility of NIRS for predicting color-related external quality parameters (L^∗, a^∗ and C^∗) as well as firmness, soluble solid content and titratable acidity. For other tested parameters (b^∗, h^∗ and pH), the results suggested that NIRS prediction was not feasible. However, the application of a LOCAL algorithm considerably improved the ability of models to predict all the internal quality parameters studied. Use of the LOCAL algorithm proved valuable in minimizing the error in NIRS models for predicting complex internal quality parameters, mainly those related to texture and acidity. Subsequently, the ability of NIR technology to classify individual strawberries as a function of variety was tested using partial least squares discriminant analysis (PLS-DA), which yielded percentages of correctly classified samples (ratio of correctly classified samples to total samples) ranging from 57% for the Camarosa variety to 78% for Antilla Fnm.     

设计参数对流浆箱简化型方锥总管内流动特性影响的研究

为了研究设计参数对简化型方锥总管内流动特性的影响,采用数值分析的方法,研究了不同的总管长度、过渡管长度及总管入口流向的条件下简化方锥总管内的流动特性。结果表明：方锥总管的基于Baines方程的简化设计法,更适用于较短的总管,随着管长的增加,压力分布和支管柬质量流量分布的均匀性明显变羞;随着过渡管长度的增加,总管入口的流动稳定性更好,总管内压力分布和支管束质量流量分布也有一定改善;不同的进口流向对总管内压力分布和支管柬质量流量分布影响较大,沿后壁流入总管明显要好于沿前壁流入。     

磨粉机粉碎流场数值模拟及参数优化

采用Fluent软件对粉碎—盘磨两级磨粉机的粉碎流场进行数值模拟研究,对比分析刀片分布方案对循环流场的影响及规律;运用正交试验设计方法对粉碎刀片进行参数优化,分析刀片偏转角、刀片长度及刀片间距对粉碎效果的影响规律,并进一步探讨刀片转速对粉碎效果的影响;为获得磨粉最佳的性能参数,对物料粉碎进行试验,以粉碎转速、粉碎时间、磨盘间隙为影响因素,以粒度合格率和耗电量为目标函数,进行三因素三水平回归试验,利用Design-Expert软件对该模型优化求解得到最佳参数组合。结果表明:刀片呈上下螺旋状分布,刀片偏转角为60°、刀片长度为120 mm、刀片间距为等距30mm时,有着良好的粉碎效果;刀片转速对物料最大剪切应变率、动压力、湍流动能的影响呈线性关系;当粉碎转速为1 500r/min,粉碎时间为20s,磨盘间隙为0.045mm时,粒度合格率(80目以上为合格)达90.4%,耗电量为118.3kJ。     

Investigations on milk flow and milk yield from teats with milk flow disorders

The objective of this study was to investigate peak milk flow, average milk flow, and milk yield in teats with milk flow disorders. A total of 100 hard milking teats were studied in 97 cows. Teats with milk flow disorders were examined endoscopically. Quarter milk flow and quarter milk yield were examined with four Lactocorders attached to a quarter milking machine. Peak milk flow, average milk flow, and milk yield were measured in all teats of the udder before treatment of the affected teat, as well as 1 and 6 mo later. Teats with milk flow disorders were compared to all other teats of the same udder. Before treatment, peak milk flow from affected teats was 20%, average milk flow 14%, and milk yield 53% of the control teats, adjusted for other significant explanatory variables. Milk flow and milk yield increased after surgical treatment of the affected teats. Six months after treatment peak milk flow was 79%, average milk flow 76%, milk yield was 71% compared with control teats. We conclude from these findings that teat endoscopy and measuring quarter milk flow and milk yield with Lactocorders are useful tools for examining teats with milk flow disorders.     

免疫磁珠结合PCR-试纸条法鉴定金枪鱼成分的研究

目的 建立一种快速检测金枪鱼成分的免疫磁珠结合PCR-免疫金标试纸条方法。方法 本研究使用免疫磁珠法提取金枪鱼样品的核酸,针对金枪鱼基因组特异性基因片段设计引物,优化反应体系和反应条件,建立金枪鱼成分PCR产物试纸条检测方法,验证方法的特异性、灵敏度和稳定性,并对市售金枪鱼产品进行检测。结果 免疫磁珠法提取市售金枪鱼样品DNA的纯度高。所建立的PCR-试纸条方法特异性强,仅金枪鱼能扩增出229bp特异性DNA片段,试纸条检测线变红,其他鱼类均无非特异性扩增条带,试纸条检测线未变红色;灵敏度高,达到0.01%;方法快速,PCR产物的试纸条判读时间5分钟。结论 该方法具有特异性强、灵敏度高、稳定性好、简便环保等优点,适用于金枪鱼成分的快速检测。     

有限宽度平板Couette流的流量计算

从有限宽度平板Couette流动的速度分布解出发,导出了有限大矩形管道流量公式,利用无穷大平板Couette流动的流量公式,给出了由管道形状决定的流量系数函数,并分析了流量公式在大宽高比和小宽高比情况下的渐近行为,导出了流量的近似公式。     

活塞流生物反应器处理印染废水

现有的印染废水生化处理的水解酸化-接触氧化(A2O)工艺流程长,处理的水质很不稳定。采用活塞流反应器(PFR)替代传统的好氧生化反应槽,采用无厌氧与兼氧消化前处理过程的好氧+絮凝组合工艺处理印染废水。工艺运行结果表明:好氧段水力停留时间(HRT)为18 h,该工序对印染废水中的CODCr、BOD5、SS、TN和TP的平均去除率分别为95.%、97.5%、92.9%、53.0%和80.0%;絮凝处理阶段CODCr平均去除率为17.2%,SS平均去除率为58.5%。处理后的水质稳定,出水水质达到了一级排放标准。     

Rheology of liquid foods under shear flow conditions: Recently used models

Proper modeling of flow or viscosity curves as a function of shear rate is a useful tool in any engineering activity. The rheology of foods depends on the composition, processing to which they have been subjected and the state of dispersion in which they are found. Liquid foods are complex biosystems, that show non-Newtonian behavior under flow conditions. This review presents models used in recent decades to describe the experimental rheological behavior of various liquid foods, ranging from Newtonian fluids to the most complex. Some non-Newtonian parameters such as those of the Ostwald-de Waele, Bingham, Herschel–Bulkley, Casson, Cross, and Carreau models are summarized. Examples of thixotropic behavior described by the Weltman and Abu-Jdayil models are also presented. In each model, explanations based on the composition and dispersion state of the food are made. This is useful in innovative processing technologies and for scientists new to the field of food rheology. An attempt is made to exemplify and group the expected behavior for most fluid foods, including some for a dysphagia diet, depending on their composition or the dispersed system formed, which will be useful for professionals who wish to compare reported rheological parameters with those obtained experimentally.     

Rapid discrimination and characterization of vanilla bean extracts by attenuated total reflection infrared spectroscopy and selected ion flow tube mass spectrometry

Vanilla beans have been shown to contain over 200 compounds, which can vary in concentration depending on the region where the beans are harvested. Several compounds including vanillin, p-hydroxybenzaldehyde, guaiacol, and anise alcohol have been found to be important for the aroma profile of vanilla. Our objective was to evaluate the performance of selected ion flow tube mass spectrometry (SIFT-MS) and Fourier-transform infrared (FTIR) spectroscopy for rapid discrimination and characterization of vanilla bean extracts. Vanilla extracts were obtained from different countries including Uganda, Indonesia, Papua New Guinea, Madagascar, and India. Multivariate data analysis (soft independent modeling of class analogy, SIMCA) was utilized to determine the clustering patterns between samples. Both methods provided differentiation between samples for all vanilla bean extracts. FTIR differentiated on the basis of functional groups, whereas the SIFT-MS method provided more specific information about the chemical basis of the differentiation. SIMCA's discriminating power showed that the most important compounds responsible for the differentiation between samples by SIFT-MS were vanillin, anise alcohol, 4-methylguaiacol, p-hydroxybenzaldehyde/trimethylpyrazine, p-cresol/anisole, guaiacol, isovaleric acid, and acetic acid. ATR-IR spectroscopy analysis showed that the classification of samples was related to major bands at 1523, 1573, 1516, 1292, 1774, 1670, 1608, and 1431 cm(-1) , associated with vanillin and vanillin derivatives.     

双层桨搅拌槽内流动特性的CFD研究

基于多重参考系法和Realizable k-ε模型,利用Fluent软件对双层CBY桨搅拌槽内不同桨间距下流场进行整体数值模拟,并将模拟结果与文献试验结果进行比较,考察桨间距对流场分布、上下层桨叶区速度及功率消耗的影响。结果表明:随着桨间距的增大,槽内流体流型由"连接流"变为"分散流",与试验结果具有较好的一致性;桨间距对下层桨叶区速度影响较大,对上层桨叶区速度影响不大;随着桨间距的增大,搅拌功率逐渐增加,单位体积功率逐渐降低。     

流动注射-火焰原子吸收光谱法联用 测定沙丁鱼中的痕量铅

本文以重金属铅(Pb)为测定对象,建立一种快速、高效、简便的检测方法测定食品中痕量的重金属,即流动注射(FI)空气混合法在线预富集与火焰原子吸收光谱法(FAAS)联用测定食品中痕量的重金属。样品溶液、络合剂和空气分别通过3条管子同时进样,金属离子和络合剂在线混合反应,其络合物流经编结反应器(KR)并吸附在其内壁,通入一段空气流,防止前后溶液混和并提高富集效果,用乙醇作为洗脱剂洗脱后送入火焰原子吸收光谱仪进行测定。与传统的流动注射与火焰原子吸收光谱法联用系统相比,此方法减少了样品的富集时间,达到了更好地吸附效果,提高了检测方法的灵敏度。该方法应用于沙丁鱼中重金属铅的测定,结果满意。     

酶水解-连续流动法测定烟草中的淀粉含量

建立了一种酶水解-连续流动法测定烟草中淀粉含量的方法,将样品先用85%乙醇去除水溶性糖,沸水浴加热使淀粉糊化,加入强碱破坏淀粉的结构,然后在淀粉葡萄糖苷酶(AGS)的作用下,淀粉将在pH=4.6的条件下水解生成葡萄糖,生成的葡萄糖使用连续流动法测定含量,推算出淀粉含量。方法回收率为96.6%,变异系数为1.52%~4.08%,说明该方法较为稳定、准确。比较了酶水解-连续流动法、酶水解法(ISO方法)、酸水解法和碘显色法测定烟草中淀粉含量的差异,并使用酶水解-连续流动法测定了国内外18个烟草样品中淀粉的含量。      

酶水解-连续流动法测定烟草中的淀粉含量

建立了酶水解-连续流动法测定淀粉含量的方法,即先用5%乙酸水溶液除去烟草样品中的可溶性糖后,再经淀粉酶酶水解,然后用连续流动法测定样品中的淀粉含量。该法的回收率大于93%,RSD=4.37%,并用该法测定了22种烤烟烟叶和8种国产烤烟型卷烟的淀粉含量。      

Investigations of milk quality from teats with milk flow disorders

The objective of this study was to investigate the quality of milk from teats with milk flow disorders. Somatic cell count, pathogens, and signs of mastitis (>100,000 cells/ml and pathogens detected) were determined in the milk from all teats of the udder before treatment of the affected teat, as well as 1 and 6 mo later. Teats with milk flow disorders were compared to all of the other teats from the same udder. Before treatment, the SCC from affected teats was 4.3 million higher, the odds of detecting pathogens 6 times higher, and the odds of mastitis 11 times higher than in control teats (when adjusted for other significant explanatory variables). SCC and the risk of mastitis decreased after surgical treatment of the affected teats, whereas the chance of detecting pathogens was not affected. Six months after treatment, the SCC was 1.3 million higher, and the odds of mastitis 6.5 times higher than in control teats. Throughout the study period neither SCC, the odds of detecting pathogens, nor mastitis changed significantly in control teats. It may be concluded from this study that milk quality from teats with milk flow disorders is decreased before treatment and does not reach the milk quality from unaffected teats within 6 mo after treatment.     

Equibiaxial extensional flow of wheat gluten plasticized with glycerol

The aim of the present work has been to study the equibiaxial extensional flow of gluten/glycerol (60/40) mixture under lubricated squeezing flow with four different crosshead speeds at room temperature. The hyperelastic model with a strain energy potential of the Mooney–Rivlin form is applied to describe the biaxial stress as a function of strain at strains below 0.7. The strain rate thinning behavior of biaxial viscosity at constant strains is revealed.