冰温气调贮藏生鲜鲢鱼片的保鲜效果

目的研究新鲜鲢鱼片在冰温气调贮藏条件下的品质变化。方法将新鲜鲢鱼片采用不同比例食盐和蔗糖调味,研究其冰点的变化情况;将鲢鱼片采用CO2(90%)+N2(10%),CO2(60%)+N2(40%),CO2(50%)+N2t(50%)等3种气调(气体均用体积分数表示,%)包装,与空气对照组一起置于冰温条件下贮藏,研究其感官评价、菌落总数、总挥发性盐基氮、pH值、总酸度、TBA值、液汁流失率等指标的变化情况。结果当食盐的质量分数为3%、蔗糖的质量分数为0.8%时,新鲜鲢鱼片的冰温贮藏范围由0~-1.97℃拓宽至0~-5.09℃;冰温气调保鲜对鲢鱼片的品质变化有一定的抑制作用,CO2(90%)∶N2(10%)包装组和CO2(60%)∶N2(40%)包装组贮藏至第16天时无异味,肌肉弹性及色泽保持较好,微生物数量小于106cfu/g,TVB-N值未超过相关限量规定,而空气对照组已于第12天时腐败。结论新鲜鲢鱼片在冰温气调条件下贮藏保鲜期可达16d以上,与单独采用冰温保鲜的方法相比,可延长货架期4天左右。     

精准冰温对鲜牛肉贮藏品质的影响

在-2.5℃的冰温和0℃、4℃三种温度条件下贮藏排酸后的鲜牛肉,定期测定牛肉出汁率、TPA指标、色泽、p H、挥发性盐基氮(TVB-N)、微生物菌落总数等品质指标,为鲜牛肉的精准冰温保鲜提供参考。结果表明:冰温库库温稳定,在4℃、0℃和-2.5℃条件下贮藏的牛肉,有效保鲜期分别为8 d、15 d和24 d。在-2.5℃条件下贮藏24 d时,鲜牛肉p H值为5.59,TVBN含量为15.39 mg/100 g,微生物菌落总数为2.2×106CFU/g,色泽鲜红,无腐败异味出现。与4℃和0℃相比,-2.5℃冰温能够有效保持牛肉的颜色,减少出汁率,减缓p H值和TVB-N含量增大,抑制微生物的生长繁殖,有效延长生鲜牛肉的贮藏保鲜时间。     

气调成分对泥鳅保藏效果的影响研究

目的根据不同气体比例气调包装生鲜泥鳅冷藏过程中的品质变化规律,确定生鲜泥鳅气调包装最佳气体组成并确定产品的货架期。方法将屠宰好的生鲜泥鳅分别以空气,CO2(75%)+N2(25%),CO2(50%)+N2(50%),CO2(25%)+N2(75%)的气体进行包装,测定4℃条件下冷藏过程中感官、微生物和理化指标的变化。结果高CO2包装组(CO2(75%)+N2(25%),CO2(50%)+N2(50%))的感官品质在贮藏过程中明显优于其他组;贮藏到10 d时,高CO2包装组的菌落总数分别为4.08和4.36 lg cfu/g,均低于临界值6 lg cfu/g,其余组均超标;CO2比例越高,其p H值在贮藏后期就越低;高CO2包装组的a*值、b*值和L*值较其他两组相比变化更加平缓,护色效果更好;从剪切值上来看,高CO2包装组对泥鳅肌肉组织结构的保护效果明显优于其他两组;在贮藏过程中,气调包装组的TBA值远低于空气包装组;第10天,高CO2包装组TVB-N值分别为6.61和9.72 mg/100 g,均未超标,其余2组均超标。结论气调包装可显著延长生鲜泥鳅的保质期;气调比例以CO2(50%)+N2(50%)为最佳,4℃条件下冷藏货架期可达10 d。     

不同气调包装对冷鲜羊肉保鲜效果研究

目的 筛选出合适的气调包装,以延长冷鲜羊肉的货架期。方法 通过测定70% N2 + 30% CO2(CO2组)、70% O2 + 30% CO2(O2组)和0.4% CO + 69.6% N2 + 30% CO2(CO组)3种气调包装和真空包装(Vac组)在4 ℃贮藏条件下,黑山羊背最长肌的菌落总数、pH、色度、挥发性盐基氮含量(Total Volatile Basic Nitrogen,TVB-N)、硫代巴比妥酸反应物值(Thiobarbituric Acid Reactive Substance,TBARS)、水分活度、水分含量、剪切力等品质指标的变化,比较不同气调包装和真空包装对冷鲜羊肉贮藏保鲜效果。结果 Vac组的微生物增殖最快,并于贮藏21 d后,微生物菌落总数达到6.32 lg(CFU/g),超过了国家二级鲜肉标准。相较于Vac组,CO2组表现出对微生物增殖的明显抑制效果,在贮藏第7天和第14天菌落总数显著低于Vac组,但CO2组对肉色的保持作用不及O2组。在贮藏的整个过程中,O2组虽然能较好地保持冷鲜羊肉的红色但同时也加速了脂肪的氧化,贮藏第14天时,TBARS值显著高于Vac组和CO2组。CO组在贮藏第14天时,菌落总数为4.15 lg(CFU/g),显著低于其他3组,符合国家二级鲜肉标准,其a*值显著高于其他3组,并且同时减缓了蛋白质和脂肪氧化速度,增加消费者的购买欲望。结论 4组不同包装的冷鲜羊肉菌落总数在第14天时均符合国家二级鲜肉标准,可以使黑山羊生鲜羊肉保鲜至14 d,其中CO组的菌落总数最低,并且pH值较低的同时能很好地维持羊肉的鲜红色,因此CO气调包装是较好的羊肉保鲜技术。     

淡腌白鱼气调综合保鲜包装研究

以白鱼为研究对象,研究不同保鲜方法对包装白鱼贮藏品质与货架期的影响。分别经辐照、气调-辐照和保鲜剂预处理后气调-辐照3种不同保鲜方法处理的淡腌白鱼,贮藏于3℃低温下,以感官评分、菌落总数、挥发性盐基氮含量、pH值为评价指标,测定贮藏期白鱼的品质变化。试验结果表明:综合保鲜处理组具有较好的保鲜效果,以菌落总数为表征的综合保鲜组的包装货架期为25 d;经气调-辐照处理的包装货架期为19 d;仅经辐照处理的包装货架期为14 d。     

气调包装协同天然保鲜剂对冷却牛肉的保鲜研究

研究了气调包装与复合天然保鲜剂联合使用对冷却牛肉保鲜的效果。将复合保鲜剂与高氧浓度的各种气调包装协同使用,并且在(4±1)℃条件下贮藏,以真空包装为对照,对牛肉菌落总数、pH值、挥发性盐基氮、液汁流失率、嫩度、弹性、色泽等指标进行检测分析,确定了延长牛肉货架期的较佳条件为:气调包装气体体积分数为70%O2/20%CO2/10%N2,复合保鲜剂为质量分数1%壳聚糖/0.2%茶多酚。     

不同包装方式对黑山羊冷鲜肉保鲜效果的比较

目的以新鲜的黑山羊肉为原料,研究真空和气调包装对山羊肉贮藏过程中感官质量、pH值、色泽、菌落总数、TVB-N值等主要技术指标变化的影响。方法将山羊屠宰后取其后腿,在-18℃下冷却到中心温度低于4℃后,去掉筋腱和脂肪,切分成约30 g的肉块,随机分成2组,装入已灭菌的包装袋内进行真空和气调包装,4℃贮藏,每隔3 d进行技术指标的测定。结果贮藏到16 d时,气调包装组的感官品质明显优于真空包装组;整个贮藏期,2组试样的pH值都低于6.6,即符合标准中对山羊肉pH值的要求;贮藏的前16 d,气调包装组的a*值高于真空包装组,表明气调包装较好地保持了羊肉的自然色泽;贮藏到16 d时,真空包装组的菌落总数为6.12,已超标,而气调包装组的试样属于次鲜肉;贮藏20 d,气调包装组的TVB-N值仍不超标,而真空包装组的TVB-N值为21.48,已超标。结论采用气调包装比真空包装好,能使山羊肉贮藏16~20 d。     

冰温及冰温气调贮藏对冬枣品质的影响

为研究在冰温及冰温气调贮藏条件下对冬枣品质的影响,本文将冬枣放于冷库预冷间进行24 h预冷,并用冰点仪按照冻结法测定冬枣的冰点温度后,按照不同成熟度分为三个等级(0级、1级、2级)的冬枣分别置于冰温(-2.4℃)及冰温气调(-2.4℃、O_2浓度5%和CO_2浓度0.5%)条件下,测定贮藏过程中不同成熟度的冬枣的失重率、果肉硬度、果皮硬度、脆性、可溶性果胶含量和Vc含量。结果表明:冰温气调贮藏可有效延缓冬枣的腐化,在整个贮藏过程中,冰温气调贮藏条件下三种等级的冬枣在失重率、脆性、可溶性果胶含量、Vc含量方面显著优于冰温贮藏(P0.05);对于果皮硬度,冰温气调贮藏下1级冬枣优于冰温贮藏,0级和2级冬枣弱于冰温贮藏;对于果肉硬度,与其它普通冷藏气调的研究对比发现冰温贮藏的效果最好,冰温气调贮藏优于普通气调;转红指数低的冬枣贮藏品质相对较好。     

不同保鲜方式对葡萄保鲜效果影响的对比研究

目的研究气调包装和微孔膜包装对葡萄贮藏期间品质的影响,为延长葡萄货架期提供依据。方法以新鲜葡萄为实验材料,分别采用O2(5%)+CO2(5%)+N2(90%)(气调1)和O2(10%)+CO2(10%)+N2(80%)(气调2)等2种气体比例(均用体积分数表示)的气调包装,以及PE参尼龙多层共挤材质的微孔保鲜膜(微孔膜)对新鲜葡萄进行包装,在温度为4℃的条件下进行贮藏,每隔48h对葡萄的硬度、pH值、可溶性固形物、可滴定酸、抗坏血酸、色度和质量损失率等变化进行测定,并进行感官评价。结果在贮藏0～12 d,从整体保鲜效果来看,微孔膜气调2气调2裸放组。结论葡萄在采后贮运期间,当葡萄的货架期≤12d时,使用3种包装均有利于延缓其衰老进程,PE参尼龙共挤微孔膜保鲜膜的保鲜效果最好。     

气调与精油等包装技术联合应用对双孢菇品质的影响

目的将天然植物精油、吸湿剂和气调包装技术联合应用于双孢菇的贮藏保鲜。方法联合组为在常温下将双孢菇PE包装袋内充入O2(体积分数为40%)+N2(体积分数为60%)、添加10μL抑菌剂(大蒜精油和肉桂精油的体积比为1∶2)和2 g吸湿剂(丙烯酸与丙烯酰胺共聚),分别设裸露空气放置和单独PE薄膜包装为对照1组、对照2组,定期测试双孢菇的感官评价、乙醇含量、失重率、褐变度、总酚含量和还原糖含量等指标。结果联合组中双孢菇感官品质得到了良好改善,减缓了褐变,降低了失重率,抑制了总酚和还原糖含量的下降,并将裸露放置保存1 d的双孢菇保鲜期延长至8 d。结论抑菌剂、吸湿剂及气调包装技术的联合应用有利于改善双孢菇贮藏品质,明显延长其货架寿命。     

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.