Chemical composition and proposed use of two semi-wild tropical fruits

The edible fruits of two native species of Southeast Asia, Baccaurea sapida (Roxb.) Muell. Arg. and Flacourtia jangomas (Lour.) Raeusch, were analyzed for sugars, amino acids and minerals. The values obtained (B. sapida and F. jangomas, based on dry weight) are: protein 5·5, 3·9%; vitamin C 178, 218 mg/100 g; fructose, α- and β-glucose and sucrose 21%, 21% total; Ca 169, 175; K 137, 158; P177, 147; Fe 100, 118; Mg 105, 57 mg/100 g. Concentrations of amino acids, Na, Mn, Cu and Zn are also reported. These fruits would be useful as supplements to a balanced diet.     

Novel mechanisms for the decomposition of 1-(amino acid)-1-deoxy-D-fructoses (Amadori compounds): A mass spectrometric approach

A study of the mechanisms involved in unimolecular mass spectral fragmentations of 1-(amino acid)-1-deoxy-D-fructoses (Amadori rearrangement products, or ARPs) has led to proposals for a number of new mechanistic routes to Maillard reaction products. One of the proposed mechanisms involves decomposition by initial dehydration or dehydroxylation directly from the cyclic hemiketal forms of the ARPs rather than from the open chain carbonyl forms. Another proposed mechanism involves formation of the pyrylium ion which could be the key intermediate in the formation of polymeric material. A number of other important Maillard reaction heterocycles could also be formed via the reactive pyrylium ion. The effect of variation of the ARP amino acid on 1,2- and 2,3-type enolization products was demonstrated. Intramolecular nucleophilic reactions observed in the mass spectral fragmentations also gave clues to the mechanisms of formation of compounds such as β-carbolenes from the tryptophan ARP.     

野木瓜果醋的澄清研究

该文以壳聚糖、硅藻土、果胶酶、琼脂、明胶-单宁作为澄清剂对野木瓜果醋进行澄清处理,并对不同澄清剂处理的野木瓜果醋澄清效果进行对比.实验结果表明,当加入3%(v/v)的明胶-单宁澄清后的野木瓜果醋透光率达89.10%,比未添加澄清剂的野木瓜果醋透光率增加了14.34%,起到了较好的澄清作用.     

Nitrosating agents from the reaction between methyl oleate and dinitrogen trioxide: Identification and mutagenicity

Dinitrogen trioxide (N₂O₃) was reacted with methyl oleate and the residual N₂O₃ removed. The resulting products were capable of nitrosating 2,6-dimethylmorpholine above 80°C with a maximum yield of nitrosamine at 130°C. N-nitroso-2,6-dimethylmorpholine formation was first order in nitrosating agent. When the reaction products were added to ground uncured pork and fried, N-nitrosodimethylamine and N-nitrosopyrrolidine were formed in amounts similar to those formed in fried bacon. 2,3-Dimethyl-2-nitro-3-nitrosobutane also nitrosated amines in the presence of pork lipids. Individual products were separated by HPLC and identified by IR and MS as nitronitroso-, dinitro-, nitronitrate-, and nitro oxime additions to methyl oleate. The nitronitroso derivative, as previously predicted, occurred in the fraction with the greatest capacity to nitrosate the amine. The products of the reaction between oleic acid and N₂O₃ were mutagenic in Salmonella typhimurium strain TA1535 without S-9 activation showing a 5·5- to 66-fold increase in revertants at doses of 90 to 200 μg/plate. These findings support, but do not prove, the theory that nitrite reacts with unsaturated lipids in bacon to form compounds which are responsible for nitrosamine formation during frying.     

A comparative study of caffeic acid and a novel caffeic acid conjugate SMND-309 on antioxidant properties in vitro

Caffeic acid (3,4-dihydroxycinnamic acid, CA) has been identified as an important source of natural antioxidants in various agricultural products. SMND-309, which is a degradation product of salvianolic acid B, is a novel conjugate of CA, but little information has been known about its antioxidant activities. In present study, we compared in vitro antioxidant activities of CA and SMND-309 using different assays such as DPPH radical scavenging assay, hydroxyl radical scavenging assay, superoxide radical scavenging assay, total antioxidant activity, reducing power, and lipid peroxidation assay. Butylated hydroxytoluene (BHT) and Vitamin C (Vc) were used as the standard antioxidants. At the concentration of 20 μg/ml, SMND-309 and CA exhibited 93.4% and 92.1% scavenging on DPPH radical, while BHT and Vc indicated an scavenging of 37.9% and 93.0% at the same concentration, respectively. Furthermore, SMND-309 is more effective on total antioxidant activity and hydroxyl radical scavenging than CA.     

Design of inductive sensors for magnetic testing of steel ropes

The design and operating principles of four inductive sensors for magnetic testing of steel ropes are presented. The magnetic concentrators can maintain the same shape as in Hall-effect leakage flux sensors, but the output signals of the inductive sensors are quite different and depend on the speed of testing. Although the inductive sensors are not as versatile as Hall-effect sensors, they are simpler in operation and can still find applications, especially in the initial and middle stages of the deterioration of the rope.     

绞股蓝多糖及其生物活性研究进展

绞股蓝是我国天然的特色资源,近年来研究发现绞股蓝多糖是绞股蓝中的主要活性成分之一。绞股蓝多糖有免疫调节、抗肿瘤、抗氧化、抗病毒、降血糖、降血脂、抗辐射等作用,对机体的毒性很小,现已开发了许多绞股蓝制品,如绞股蓝茶、皂甙片、冲剂、胶囊、口服液、糖丸等,另外还有作为绞股蓝饮料、运动饮料及可乐和啤酒等食品的添加剂。主要对绞股蓝多糖的组成、提取工艺、生理作用和应用前景进行综述。     

铜在鲫鱼体内的积累特征研究

通过半静态法将鲫鱼暴露于不同浓度的铜溶液中,研究了不同时间段铜在鲫鱼内脏、鳃及肌肉中的积累特征,通过曲线拟合研究铜在鲫鱼诸部位的积累量随暴露时间的变化特征。结果表明,铜在内脏、鳃及肌肉中的积累量均随暴露时间的增加而增加,在内脏和肌肉中积累速率由快到慢,拟合结果显示积累量与暴露时间的对数呈线性关系;鳃中积累量与暴露时间在低浓度时呈直线关系,高浓度时呈对数关系。鱼体各部位对Cu的积累能力为内脏>鳃>肌肉,且内脏中Cu的积累量大大高于鳃及肌肉。最大生物浓缩系数(BCF)值计算表明,在较低浓度下,鲫鱼对重金属Cu具有极强的积累作用。     

纳米锰锌软磁铁氧体的制备及其产品表征

以氯化铁、二价金属离子(锰、锌、镍)的硫酸盐为原料,在微量FeSO4催化剂的作用下,通过沸腾回流反应制备出前驱体,再经140℃干燥得到纳米锰锌软磁铁氧体产物。然后运用TG-DTA、XRD、SEMF、T IR等检测手段对前驱体及产物的物性和结构进行表征,结果表明该法具有工艺简单、生产效率高、反应时间短、条件温和、产品矫顽力小等优点,产物是理想的纳米级软磁性锰锌铁氧体材料。     

HPA/SiO2光催化降解甲基橙的研究

用溶胶-凝胶法制备了负载型杂多酸催化剂HPA/SiO2。在光化学反应仪中,以紫外灯为光源,以HPA/SiO2为光催化剂,研究了其对模拟染料废水甲基橙溶液的光催化脱色降解的影响。讨论了影响催化降解效果的重要因素:不同正硅酸乙酯与磷钨酸的配比,溶液初始酸度,催化剂投加量等。在300 W的紫外灯光照下,讨论了HPA/SiO2光催化剂的重复使用性。最后,研究了该条件下10 mg/L的甲基橙溶液的动力学。