Microstructure, fundamental rheology and baking characteristics of batters and breads from different gluten-free flours treated with a microbial transglutaminase

Gluten is a fundamental component for the overall quality and structure of breads. The replacement of the gluten network in the development of gluten-free cereal products is a challenging task for the cereal technologist. The functionality of proteins from gluten-free flours could be modified in order to improve their baking characteristics by promoting protein networks. Transglutaminase (TGase) has been successfully used in food systems to promote protein cross-linking. In this study, TGase was investigated for network forming potential on flours from six different gluten-free cereals (brown rice, buckwheat, corn, oat, sorghum and teff) used in breadmaking. TGase was added at 0, 1 or 10 U/g of proteins present in the recipe. The effect of TGase on batters and breads was evaluated by fundamental rheological tests, Texture Profile Analysis and standard baking tests. Three-dimensional elaborations of Confocal Laser Scanning Microscopy (CLSM) images were performed on both batters and breads to evaluate the influence of TGase on microstructure. Fundamental rheological tests showed a significant increase in the pseudoplastic behaviour of buckwheat and brown rice batters when 10 U of TGase were used. The resulting buckwheat and brown rice breads showed improved baking characteristics as well as overall macroscopic appearance. Three-dimensional CLSM image elaborations confirmed the formation of protein complexes by TGase action. On the other side, TGase showed negative effects on corn flour as its application was detrimental for the elastic properties of the batters. Nevertheless, the resulting breads showed significant improvements in terms of increased specific volume and decreased crumb hardness and chewiness. Under the conditions of this study, no effects of TGase could be observed on breads from oat, sorghum or teff. Overall, the results of this study show that TGase can be successfully applied to gluten-free flours to improve their breadmaking potentials by promoting network formation. However, the protein source is a key element determining the impact of the enzyme.     

Studies on the Molecular Structure of Vessels in Secondary Xylem of Stem from Three Carambola Varieties

[Objective] The aim of this study was to provide the theoretical basis for variety identification of carambola and pomiculture.[Method] The molecular structure of vessels in stem secondary xylem from three carambola varieties of Malaysia 8,Misi and Malaysia B17 were studied by cell image analysis system and microphotography.[Result] The molecular structure of vessels in stem secondary xylem from carambola was as follows:the first type had tails in two ends,the second type had tail in one end,and the third type had no tails in two ends.The average length of vessel elements was from 328.88 to 366.09 μm,while its average width was from 44.61 to 52.43 μm.Most of the end wall was simple perforation plates,while the alternate-opposite pitting was the major forms of pitting.[Conclusion] Most characteristics of vessel elements from carambola were evolutionary characters of vessel elements in the process of phylogeny,but there were more primitive characters,for example,both two ends of vessel had tails or just one end had tail,and end wall was inclined.The molecular structure of vessel from carambola was in accordance with its ecological adaptability,and the growth characteristics of different varieties were also in accordance with the difference of molecular structure of vessel.     

鳞翅目蛾类卵形态的比较研究

利用显微观察并描述了鳞翅目亚麻篱灯蛾、驼波尺蛾、榆绿天蛾、雪毒蛾、灰双纹螟、尖锥额野螟、银锭夜蛾、荒夜蛾卵壳的形态特征。结果表明，不同种类蛾卵受精孔的数目；受精孔区花饰的形状、数目、排列方式；气孔的位置与排列均存在明显的差异，这些差异为卵的分类提供了依据。     

柠檬酸盐对黑云母表面溶解及微结构变化的影响

采用离位培养法,结合原子力显微镜的接触成像和相位成像模式研究层状硅酸盐含钾矿物黑云母在根际环境条件下的表面溶解现象和矿物微结构转化过程。结果表明,在p H 4.0的弱酸水溶液中反应24 h时,黑云母(001)面上有微型蚀坑出现,其深度介于0.1~0.9 nm之间,表面变得比较粗糙;反应96 h时,黑云母(001)面上蚀坑较为明显,但仅占总表面的4.8%,蚀坑的深度平均为0.957 nm;反应140 h时,黑云母(001)面上有不稳定的覆盖物沉积,阻碍表层溶解过程的持续进行。在p H 4.0的柠檬酸溶液中,经过24 h培养,(001)面上有大量的蚀坑出现,单层溶解现象明显;48 h时,表面台阶溶解速率显著提高,溶解面积可达总表面的48.7%;140 h时,(001)面上有圆形状胀裂发生,表层(高度,1~2 nm)发生破裂、产生较多的黑云母碎片,溶解速率进一步提高。随着柠檬酸溶液中Na+浓度的增加,表层溶解速率增强,(001)面上也有次生覆盖物沉积。同时,界面上Na+-K+交换作用加剧,表层结构(高度,2~10 nm)胀裂现象更加明显。随着反应时间的延长,140 h时,黑云母(001)面的深层结构(深度,~20 nm)亦逐渐隆起并引起周边区域产生裂缝(深度,0.1~1.9 nm),最终导致表层微结构区域水化,形成水化云母(伊利石)。     

毛发微观结构的应用与技术发展

毛发微观结构研究技术经历了光学显微技术和目前的多种显镜技术。主要应用领域涉及野外对动物种类及数量的调查、动物食性的研究、保护野生动物资源,辅助执法、毛纺业原料鉴定的研究和应用、头发养护和脱发治疗、法医物证检验等。虽然毛发微观结构在上述应用中仍存在一定的局限性,但是其重要作用是无可替代的,将来毛发的3D结构将是主要发展方向。     

蓝狐消化道显微结构

本文应用光学显微镜对蓝狐消化道显微结构进行了较为详细的观察，并与其它动物进行了比较。结果表明，蓝狐食管腺数量较多，苏木素深染，胃贲门腺区为邻接贲门约１．４ｍｍ左右的狭长区，其中贲门腺不含壁细胞及主细胞，由柱状细胞构成。胃底腺壁细胞含量较多。十二指肠仅在近幽门１ｃｍ的范围内具有粘膜下腺。在十二指肠部，胆管在粘膜下层形成长约１．５－２ｃｍ的壁内段。     

山羊甘肃棘豆中毒睾丸、附睾的病理学研究

山羊甘肃棘豆中毒睾丸、附睾的病理学研究丁伯良，王建辰，薛登民，贾维真，王淑娥（西北农业大学兽医系，杨陵７１２１００）马远莉（陕西省农科院农业测试中心）摘要对６只１０月龄西农莎能奶山羊公羊每日按１０ｇ／ｋｇ剂量单笼饲喂甘肃棘豆粉，４只同龄公羊作对照。１...     

黄鳝精巢显微和超微结构的研究

通过光镜和透射电镜研究雄鳝和雌雄间体鳝性腺。结果表明：①精巢的发育可分为六个时期；②精子细胞变态过程中，细胞核染色质的变化为细颗粒状→粗颗粒状（小团块）→高电子密度的均质物：③精子分为头部、颈部和尾部，头部为圆形，无顶体；④雌雄间体鳝的精细胞与同期雄鳝的精细胞发育程度基本相同。     

Improvement of water-stability of clay aggregates admixed with aqueous polymer soil stabilizers

Aqueous soil stabilizers improve soil properties. Water-stability of soil aggregates was determined using two different soil stabilizers: S-type and E-type. Various concentrations of the two soil stabilizers were tested in soil aggregates that were bigger than 5 mm but smaller than 10 mm. Testing the aggregates using the static water-measure method showed that the water-stability index, K, increased with the concentrations of soil stabilizers. S-type soil stabilizer in concentrations ranging between 20% and 40% resulted in K-values between 64.0% and 83.8%, and E-type polymer emulsions in concentrations between 3% and 7% resulted in K-values between 90.1% and 99.7% respectively. The soil aggregates admixed with water resulted in a K-value of 11.5%, which was tested as a control. Two aggregate collapse models were found and discussed based on the collapse characteristics of the modified aggregates: S-type soil stabilizer in low concentrations follows a gradual collapse pattern, while S-type stabilizer in high concentrations and E-type stabilizer in low concentrations follow an explosive collapse pattern. These patterns depend on the formation of a membrane structure on the surface of the aggregates through physicochemical bonding. By identifying the mechanisms of the membrane structure and calculating the K-values, significant information on the improvement of soil properties can be determined.     

盐度骤变对金钱鱼幼鱼鳃线粒体丰富细胞形态结构的影响

文章采用显微技术研究了盐度骤降(20盐度组投入5盐度组)、盐度骤升(20盐度组投入35盐度组)胁迫下,金钱鱼(Scatophagus argus)幼鱼鳃线粒体丰富细胞(Mitochondria-rich cells,MRCs)形态结构的变化。结果显示,低盐胁迫3 h MRCs长径[(9.517±1.390)μm]和短径[(7.150±1.448)μm]较对照组长径[(7.317±0.986)μm]和短径[(5.067±0.467)μm]显著增大(P<0.05),高盐胁迫6 h MRCs数量显著增加。显微结果表明,胁迫24 h鳃丝处于渗透机制的主动调节阶段;超微结构观察发现鳃丝分化出2种类型的MRCs:1)Ⅰ型MRCs,椭圆形,胞核形状不规则,内脊发达,顶端开口处于关闭或开放状态,主要存在于低盐环境;2)Ⅱ型MRCs,圆形,胞核规则呈圆形,具有多个顶端开口。具不同形状的线粒体,a型线粒体着色较浅,呈短粗状;b型线粒体着色较深,呈小的颗粒状,主要存在于高盐环境。综上所述,金钱鱼幼鱼对盐度骤变产生应答反应机制,通过MRCs体积、数量、形状结构,以及线粒体的形状结构变化共同维持内环境稳定。