Effect of microwave cooking on the microstructure and quality of meat in goat and lamb

Fat cell distribution in the structure of semimembranosus muscle of goat and lamb was studied. The effect of various heating methods including conventional, domestic and industrial microwave were investigated using fluorescent light microscopy. Frequency used for microwave heating was 2450 MHz with two wattages levels of 700 (domestic microwave) and 12000 (industrial microwave). All samples were heated to internal temperature of 70 °C. The roasted samples in conventional oven were compared with microwave cooking. Fat distribution was different in various heat treatments. The roasted samples had greater fat retention in semimembranosus muscle. Results showed that uneven distribution of fat in muscle system influenced fat loss during cooking. The fat cells in the interior of muscle were lost more slowly compared to the fat located near the surface of the muscle. The overall migration of fat globules during microwave cooking was higher than conventional cooking.     

家用洗涤剂对洗涤织物的荧光作用

采用市售的多种洗涤剂对棉、真丝织物进行洗涤,分别考察了洗涤剂种类、质量浓度、洗涤时间和温度对织物荧光效果的影响。结果表明:洗涤剂对白色、浅色织物的荧光作用较深色面料显著,洗涤织物的荧光白度随洗涤剂质量浓度的增加而提高,洗涤时间和洗涤温度对织物荧光作用的影响因洗涤剂种类不同而存在明显差异。     

A critical evaluation of fluorescence as a potential marker for the Maillard reaction

During storage of foods and biological systems, fluorescent products are developed through the Maillard reaction, along with the brown pigments. Fluorescent products have been proposed as early indicators of this reaction. The aim of present work was to compare the kinetics of fluorescence and pigment development in order to define adequate early markers. Model glucose–aminoacid systems were prepared in several salts and buffers and stored at 55 °C. Pigment and florescence development was evaluated as a function of time. The results showed that, under unfavourable conditions for the reaction (low pH, presence of retardant salts), fluorescence was detected after important colour changes had occurred. However, under favourable conditions for the reaction (neutral pH, accelerating salts) fluorescent products could be considered as adequate markers because they sensitively reflected early steps of the reaction. Compositional factors and/or environmental conditions are the key factors for defining the performance of fluorescence as an adequate early marker.     

铕掺杂配合物的合成及其在荧光防伪油墨中的应用研究

荧光防伪油墨是目前防伪包装印刷中使用最为广泛的防伪油墨之一,稀土配合物作为荧光颜料制成的荧光防伪油墨具有发射光谱窄、色纯度高、荧光效率高、稳定性好等特性。本文以铕(Eu3+)为中心体,掺杂非荧光惰性离子钆(Gd3+),以对甲氧基苯甲酸(POA)为第一配体,邻菲咯啉(Phen)为第二配体合成了相应的钆掺杂铕配合物。测定了其红外光谱,表明该系列掺杂配合物具有相似的结构,配位成功;研究了其荧光性能,掺杂离子Gd3+对配合物荧光性能的影响,结果表明掺杂离子钆的加入能提高配合物的荧光强度,钆和铕的最佳配比为1:9;同时制备了荧光防伪油墨,并研究了其荧光性能及相应印刷适性,结果表明该荧光油墨表现为铕离子的特征荧光发射,在日光下观测印迹无色,在紫外光下呈现明显红色荧光。     

A novel sensitive staphylococcal enterotoxin C1 fluoroimmunoassay based on functionalized fluorescent core-shell nanoparticle labels

A highly sensitive fluoroimmunoassay for the determination of staphylococcal enterotoxin C₁ (SEC₁) is proposed. It is based on the functionalized fluorescent core-shell nanoparticles as the labels coated with anti-SEC₁ monoclonal antibodies in “sandwich” fluoroimmunoassay. With the simple, inverse microemulsion polymerisation method, the functionalized fluorescent core-shell nanoparticles were prepared easily. The preparation process produces a silica shell on the surface of the Ru(bpy)₃Cl₂ (Rubpy) dye with one step cohydrolysis of tetraethylorthosilicate (TEOS), and the coupling agent (3-aminopropy1)triethoxysilane (APS) provided the amine groups that can be used for biological conjugation. The nanoparticles were then labeled with the anti-SEC₁ monoclonal antibodies and the antibody-labeled nanoparticles were successfully used for the determination of SEC₁. The calibration graph for SEC₁ was linear over the range 1.0–75.0 ng ml⁻¹ with a detection limit of 0.3 ng ml⁻¹. The regression equation of the working curve was I_F = 24.583 + 0.6426[SEC₁] (ng ml⁻¹) (r = 0.9991). The relative standard deviation (RSD) for five parallel measurements of 25.0 ng ml⁻¹ SEC₁ was 2.5%. Furthermore, the application of fluorescence microscopy imaging in the study of the antibody labeling and sandwich fluoroimmunoassay with the functionalized fluorescent core-shell silica nanoparticles was also explored. The results demonstrate that the method offers potential advantages of easily labeling to the antibody, sensitivity, simplicity and reproducibility for the determination of SEC₁ and is applicable to the determination of SEC₁ in real samples and enables fluorescence microscopy imaging for the determination of SEC₁.     

单波段紫外光对荧光增白剂的衰减的影响的研究

荧光增白剂广泛的应用于增加纸张的亮度和白度。它会因曝光在光源下而衰减,特别是在加速衰减的测试中和暴露在特殊视觉环境下会产生重要的变化。在本次试验中,我们使用单色仪将含有荧光增白剂的印刷用的纸张暴露在单波段350纳米的光源下,探寻纸张反射率的变化。结果显示增白剂的衰减非常的微弱,但是快速的衰减主要集中在第1个小时,造成衰减的区域在380nm到420nm之间。实验总共持续了7.5个小时,造成纸张的色差接近0.5。     

荧光样品的白度测定

通过大量实验对ＣＩＥ１９８２白度公式进行评定,从色泽度、亮度因素及兴夯纯度等方面来论述ＣＩＥ１９８２白度公式存在的缺陷,推荐一个新的白度公式。并对ＣＩＥ白度空间作了论述,提出今后对ＣＩＥ白度空间和白度公式作进一步研究的方向。     

新型棉用荧光增白剂CPC的应用

分别采用荧光增白剂ＣＰＣ、ＶＢＬ对棉织物进行增白处理，探讨了温度、ｐＨ值、Ｈ２Ｏ２等因素对增白效果的影响。研究表明，ＣＰＣ增白剂具有更高的白度和耐酸碱稳定性。     

荧光素作吸附指示剂测定1227表面活性剂的含量

本文以荧光素作沉淀吸附指示剂，用ＡｇＮＯ３滴定１２２７表面活性剂中的Ｃｌ＾－离子，从而测出１２２７表面活性剂的含量，方法快速，简便，结果令人满意。     

含荧光染料织物的真实反射率及荧光量子效率

荧光染料有异于常规染料的光学特性。文章介绍了一种简便的方法,可得到含荧光染料织物的真实反映率。在此基础上,提出了荧光染料的荧光量子效率的简便求解方法。     

荧光染料发射区量子效率及其配色

荧光染料有特殊的光学特性,本文应用发射区荧光染料反射率表达式,对荧光染料配色问题进行了研究,并得到较理想的效果。     

荧光增白剂（三）

2.11　萘二甲酰亚胺类荧光增白剂众所周知 ,在荧光染料中 ,4 -氨基萘二甲酰亚胺是黄绿色的荧光染料 ,因为不能发射蓝色荧光而不能用作荧光增白剂 ,但当 4 -氨基被乙酰化后 ,其荧光便转变为蓝光 ,因此可作为荧光增白剂 ,这便是 BASF公司首先生产的 Ultraphor APL,其结构式为 :N?丯HCOCH3OCH2 CH2 CH3OUlitraphor APL目前使用的萘二甲酰亚胺类荧光增白剂主要是4 ,5位上不是氨基而是烷氧基的衍生物 ,其通式为 :N丷1丷2OR3O具有此结构的荧光增白剂商品及取代基如表 8所示。它们用于涤纶时耐光牢度优良 ,用于腈纶时耐亚氯酸钠漂白牢…     

荧光增白剂（二）

２．３双乙酸胺基取代物荧光增白剂 双乙酰胺基取代物的基本结构为： 这类荧光增白剂适用于棉和锦纶的增白,特别是加入到洗涤剂中,它对纤维素纤维具有高亲和力及中等的耐氯漂牢度,但在沸水中稳定性较差,日晒牢度也欠佳。 荧光增白剂Ｒ（Ｂｌａｎｋｏｐｈｏｒ Ｒ）即为此类组分： 这类增白剂适用于棉和蛋白质纤维,具红紫色荧光,且荧光强。在此基础上,如引入含氟基团,则是纤维素纤维、蛋白质纤维有效的增白剂。 其不对称的荧光增白剂适于棉和纸张的增白。如：２．４ 三氮唑类荧光增白剂 二苯乙烯三氮唑类荧光增白剂也是广泛使用的增白…     

荧光增白剂（一）

评述了国内外荧光增白剂的发展过程,分析了增白原理和各类增白剂的结构,介绍了商品增白剂的化学结构,并对增白剂的拼混、泛黄点和应用过程 如何提高日晒牢度等研究工作进行了归纳。     

Surface Characterization of Caramel at the Micrometer Scale

ABSTRACT: The surface of caramel has been imaged using pulsed force atomic force microscopy (AFM) and scanning thermal microscopy, revealing shallow depressions in the surface of 1 to 10μm in dia that have a higher adhesion to the silicon AFM probe and a lower stiffness and different thermal character than the surrounding sample. This is consistent with the view of caramel as fat droplets within a matrix of sugars. As confirmation, the depressed regions were identified by infrared microscopy as consisting mainly of fat in a matrix of sugar. AFM also reveals that regions surrounding the depressions are decorated with thin (about 6nm) plate-like features that display a higher stiffness than the rest of the matrix. We propose that these are of crystalline origin and most probably consist of fat.     

涤纶荧光增白剂的现状及应用

文章介绍了涤纶荧光增白剂的现状及应用情况，通过国内外产品的筛选和对比，以德国Ｂｅｙｅｒ公司ＢｌａｎｋｏｐｈｏｒＥＲ３３０最理想，其同类产品荧光增白剂ＰＳ－１，ＪＨ－１是国内涤纶荧光增白剂的发展方向。     

用激光共聚焦显微镜表征涂层厚度对油墨渗透的影响

涂布纸的涂层结构对纸张的光学性能、物理性能和印刷质量有很大的影响。油墨转移到纸张上并在涂层表面固着渗透,其固着渗透情况最终影响印刷品的质量和油墨的使用。目前有关油墨渗透的研究报道中较为精确的是切割法,但切割的过程对于纸张有一定的损伤性,使测量结果的可靠性大大降低。本实验的主要目的是用激光共聚焦显微镜表征涂布纸的涂层厚度对油墨渗透的影响,并对其渗透深度和渗透轨迹进行定量化研究。在实验中选用荧光油墨作为激光共聚焦显微镜观察描绘油墨的渗透深度和分布的印刷油墨,将所有的XY平面图像进行重构得到油墨颜料渗透的三维图像。实验研究表明用激光共聚焦显微镜表征油墨颜料的渗透深度和分布的均匀程度是有效和可靠的,这种方法对实验对象无损伤性,利用荧光油墨中的荧光颜料作为示踪剂,省去了荧光着色等步骤,减小了人工操作的误差。实验结果证实纸张的印刷质量可以通过增加涂布时涂层厚度的方法来调整和改善。     

荧光重组酶介导等温扩增快速检测食品中克罗诺杆菌属

目的 克罗诺杆菌属为乳制品及婴幼儿配方制品中常见污染的食源性致病菌,传统的培养法检测无法满足口岸大批量食品的快速检测要求。建立快速简便的荧光重组酶介导等温扩增法(recombinase-aided amplification, RAA)检测克罗诺杆菌属,以满足口岸快速通关及监管需要。方法 根据克罗诺杆菌属ompA 基因保守区设计特异性引物、探针,通过引物两两组合结合探针筛选出扩增效率及灵敏度最佳的引物组合,优化反应温度及引物探针浓度,确定最佳反应条件。将建立的荧光RAA法应用于食品基质及实际样品检测中,同时与国标GB 4789.40-2016进行比对验证。结果 克罗诺杆菌属荧光RAA最佳反应温度为39℃,最佳引物、探针终浓度均为400nmol/L。建立的荧光RAA法特异性强,纯菌灵敏度达到3×10_² CFU/ mL。加标食品基质婴儿奶粉及婴儿米粉在月桂基硫酸盐胰蛋白胨肉汤-万古霉素(mLST)增菌只需2h,即可检测原始浓度达到3×10_^-2 CFU/ mL的克罗诺杆菌属。荧光RAA法只需5min即可观察结果,20-30min完成扩增,速度及灵敏度明显高于国标法。结论 荧光RAA法简便、快速、无需大型仪器,可用于口岸或其他场所进行克罗诺杆菌属的快速检测与监控。     

Viability assessment of lactic acid bacteria in commercial dairy products stored at 4 °C using LIVE/DEAD® BacLightTM staining and conventional plate counts

The viability of lactic acid bacteria (LAB) from commercial fermented milks was studied during storage at 4 °C. The enumeration of total viable bacteria was assessed using fluorescence microscopy. Plate counting on selective media was used to enumerate LAB. Using LIVE/DEAD® BacLight^TM viability staining, it was observed that bacterial counts decreased gradually after expiry dates, the number of viable bacteria remaining above 10⁶ bacteria g^?1 for all of the products. Viable cell counts estimated by plating onto selective media were lower than those obtained by direct microscopic counting. The viability of LAB contained in acid products decreased during their storage period at 4 °C. All products contain viable LAB ranging from 10⁸ to 10⁹ bacteria g^?1 and could be considered as probiotic, given that the recommended minimum number of probiotic bacteria in such food products is approximately 10⁷ bacteria mL^?1 product. The number of bifidobacteria in commercial fermented milks declared to contain bifidobacteria varied from 10⁴ to 10⁷ bacteria mL^?1. This study confirms the usefulness of fluorescent techniques for a rapid and accurate evaluation of bacterial viability in probiotic products.     

用激光扫描共聚焦显微镜定量检测烟草花粉自发荧光强度

应用激光扫描共聚焦显微镜（ＬＳＣＭ）对３个类型共６个烟草材料的花粉自发荧光强度进行了定量检测，发现不同类型及品种之间花粉自发荧光强度存在明显差异。应用ＬＳＣＭ检测烟草花粉自发荧光强度可做为烟草品种鉴别的重要依据。