猪肉包装用新鲜度指示卡研究

选用溴甲酚紫为指示剂,制备了一种应用于冷鲜猪肉包装的新鲜度指示卡。将制备的新鲜度指示卡置于50,100,150 g 3种不同质量的猪肉包装中,由挥发性盐基氮表示猪肉的新鲜程度,色差与感官评定分数标示指示卡的颜色变化,观察猪肉的新鲜程度与指示卡颜色变化的相关性,从而判断指示卡的有效性。试验结果表明,所制备的新鲜度指示卡色差变化与猪肉挥发性盐基氮变化呈线性关系,并且不受包装猪肉质量的影响;当猪肉新鲜度降低到一定程度时,指示卡由黄色变为绿色。因此,所制备的新鲜度指示卡可以用于指示包装猪肉的新鲜程度。     

花青素/姜黄素智能标签的制备及应用

目的 制备基于红甘蓝花青素和姜黄素混合色素的智能指示标签,应用于猪肉的新鲜度指示,并对指示标签的新鲜度指示效果进行评价。方法 将红甘蓝花青素和姜黄素按照体积比为2︰1混合作为新鲜度指示剂,以卡拉胶为成膜基质,研究其针对环境pH值变化的响应性;以猪肉为研究对象进行室温（25 ℃）和冷藏环境（4 ℃）下的保存实验,研究其挥发性盐基氮（TVB-N）含量变化与变色的关系,评价智能指示标签的效果。结果 在猪肉的保存实验中,随着猪肉TVB-N值的升高,室温和冷藏条件下的指示标签都相应地产生3个不同的颜色变化,其中当TVB-N值小于0.15 g/kg时,指示标签呈绿色;当TVB-N值在0.15~0.20 g/kg之间时,指示标签开始由绿色向黄色转变;当TVB-N值大于0.20 g/kg时,指示标签完全呈黄色。指示标签的变色与理化指标相匹配。结论 红甘蓝花青素/姜黄素智能指示标签在不同温度条件下,都具有随TVB-N值变化而发生变色的能力,具有应用于猪肉新鲜度检测的潜力。     

基于玫瑰茄色素的鱼肉新鲜度指示标签

目的选用玫瑰茄提取的色素作为p H指示剂,制备一种用于鲜白花鱼新鲜度检测的指示标签。方法将质量分数为2%的玫瑰茄乙醇溶液分别取1,3,5,7,9 m L加入50 m L壳聚糖-淀粉成膜液中,制得5组食品新鲜度指示标签,分别贴于在3组4℃温度下进行保存的100 g新鲜鱼肉表面,并利用食品保鲜薄膜对鱼肉和托盘进行密封包装。通过以24 h为1周期对鱼肉的挥发性盐基氮、p H值和鱼肉的气味、外观、肌肉组织等感官变化情况进行检测与评价,并对食品新鲜度指示标签的颜色进行测定以及感官评价。结果膜液中的玫瑰茄色素溶液添加量达到7 m L时,指示标签由紫红变为灰绿,并在实验后期颜色逐渐向绿色靠近,颜色变化明显。结论玫瑰茄色素可用于鱼肉新鲜度检测,指示效果较好。     

紫甘薯色素智能指示剂墨水的制备与性能研究

采用超声波辅助溶剂法提取紫甘薯色素,探讨其对pH值的敏感性和光稳定性,再将其制备成墨水喷印成新鲜度指示标签,考察该标签在食品腐败气氛下的色差变化。实验发现:紫甘薯色素溶液的颜色随溶液pH值的变化而发生改变,当pH值由4.0升至11.0时,紫甘薯色素溶液由粉红色逐渐变为绿色,当pH值继续增大时,溶液呈现浅绿色;紫甘薯色素在避光或室内自然光环境中性质较稳定,但室外光对其稳定性有较大影响;以质量分数为50%的乙醇溶液为溶剂,配制的质量浓度为30 g/L的紫甘薯色素喷墨打印墨水,其表面张力为30.92 mN/m、黏度为2.48 mPa·s(20℃),符合喷墨打印墨水规定的表面张力范围,且制备的新鲜度指示标签在模拟食品腐败气氛下,色差变化ΔE值基本满足人眼识别的要求。     

食品包装用比色型CO2指示油墨

为了方便直观地监测食品包装内部的CO2 含量,利用CO2敏感型指示剂即甲基红和溴百里酚蓝分别溶于体积分数为50%的乙醇溶液,制得质量分数均为0.1%的甲基红-乙醇溶液和溴百里酚蓝-乙醇溶液,并以甘油和甲基纤维素为主要成胶材料调制油墨,并建立了“油墨颜色-pH值-CO2含量”模型,最后以平菇为试验对象,验证比色型CO2指示油墨的检测效果,并将油墨与指示剂溶液的变色效果进行对比。试验结果表明：在甲基红和溴百里酚蓝的质量比为3:2,甘油的体积分数为4%,甲基纤维素的质量分数为1.72%的条件下,可制备比色型CO2指示油墨;该油墨通过丝网印刷可直接印刷在塑料薄膜上,且在不同体积分数的CO2（0~100%）下其颜色变化显著;在平菇包装内,比色型CO2指示油墨与指示剂溶液的变色效果吻合度较高,且利用“油墨颜色-pH值-CO2含量”模型计算得到的结果与试验结果基本一致。可见,本指示油墨能够在一定湿度条件下直观地指示包装内CO2含量。     

低温气调包装对鲜猪肉保鲜效果的影响研究

按5种气调方式包装新鲜猪肉,于低温(约3.79℃)下储存,检测了鲜猪肉挥发性盐基氮(TVB-N)含量、pH值、感官指标和包装内的气体组分含量等指标。实验结果表明:采用高氧气调包装,鲜肉货架寿命长达24d,且能够保持猪肉的鲜红色,较适宜用于鲜肉冷链运输和货架销售;抑菌剂在低温储存环境中,能将鲜猪肉的货架寿命延长25%。     

基于改性玫瑰茄花青素的新鲜度指示膜研制及其在鲳鱼包装中的应用

目的将一种基于改性玫瑰茄花青素的新鲜度指示膜用于鲳鱼保鲜包装,并对指示膜的新鲜度指示效果进行评价。方法以酰化改性玫瑰茄花青素为新鲜度指示剂,聚乙烯醇为涂布液基质,聚丙烯为基膜,制备新鲜度指示膜,研究其对挥发氨的响应性;以鲳鱼为研究对象进行包装应用试验。结果随着挥发氨浓度的增大,指示膜颜色由红变紫再变绿;鲳鱼由新鲜级变为次新鲜级直至腐败级时,指示膜颜色均发生变化,具有与鲳鱼样本品质较强的关联性;指示薄膜颜色变化主成分得分呈明显的聚类趋势,与样本新鲜级相对应;基于偏最小二乘回归的TVB-N模型能有效预测鲳鱼的TVB-N值。结论新鲜度指示膜具有用于鱼类产品新鲜度检测的潜力。     

pH敏感型指示纸的制备及在猪肉品质检测中的应用

目的对猪肉的腐败程度作出更加便捷的预测。方法选取溴甲酚紫为反映猪肉新鲜程度的pH指示剂,添加甘油制成混合型气敏凝胶,并以棉质纤维纸为基材制备指示纸,利用涂覆设备在基材上涂覆指示剂。随后将制得的指示纸应用于猪肉。结果经响应面法分析得到了最佳工艺组合,羟乙基纤维素添加量为1.70 g/(100 g),甘油添加量为5.00 mL/(100 mL),指示剂溶液添加量为9.00 mL/(100 mL),涂覆厚度为4 mm。结论猪肉腐败的程度与pH指示纸的颜色变化一致,具有一定的实际应用价值。     

食品新鲜度智能指示卡的研究进展

目的综述食品新鲜度指示卡的原理、特点和研究进展。方法查阅相关文献,对以CO2、挥发性含氮化合物、硫化氢、pH值变化、微生物代谢物为颜色变化指示物的新鲜度指示卡的研究现状及应用进行总结。结论新鲜度指示卡具有科学、直观和方便的技术特点,在未来包装市场具有无限的潜力。目前新鲜度指示卡行业需要走出精度和稳定性欠佳的困境,还需要在保证食品安全方面继续努力,真正实现食品包装的功能化、智能化和信息化,保证其质量的可靠性和安全性,早日走向大众市场。     

蓝莓新鲜度指示剂研究

目的研究一种以蓝莓花青素为原料制作的蓝莓新鲜度指示剂,并应用于蓝莓包装,用以指示蓝莓果实在运输贮藏过程中新鲜度的变化情况。方法以新鲜度指示剂在蓝莓贮藏期间的色差值作为考查指标,对影响色差值的因素进行研究。首先通过单因素试验研究果皮浓度、滤液pH值和滤纸浸泡时间对指示剂色差值的影响,然后利用正交试验法优化最佳工艺条件。结果由正交试验分析结果得出蓝莓新鲜度指示剂最佳工艺条件,果皮质量浓度为4 g/(100 m L)、滤液pH值为12、滤纸浸泡时间为1.5 min,该条件下新鲜度指示剂的色差值为54.69。结论通过正交试验法获取最优制作工艺的蓝莓新鲜度指示剂,该指示剂具有明显的颜色界限,是一种实用的蓝莓包装标签。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.