Ultrasound-induced destruction of low levels of estrogen hormones in aqueous solutions

The removal of estrogen hormones from water and wastewater is of importance due to their adverse effects toward ecosystems and potential risks to human health. The ultrasound-induced destruction of estrogen compounds in aqueous solutions is studied in a batch reactor using a 1.1 W/mL sonication unit and in a continuous flow reactor using a 2.1 W/mL sonication unit. The estrogen compounds of interest are 17alpha-estradiol, 17beta-estradiol, ethinyl estradiol, estrone, equilin, gestodene, levonorgestrel, and norgestrel. Effects of process variables such as temperature, pH, and pressure are examined. The degradation of estrogens follows pseudo first-order kinetics. The reaction likely takes place in the interfacial region where supercritical environment is produced upon cavity implosion and in the bulk solution with radical species. Low solution pH is more favorable for destruction of estrogens. A kinetic degradation model is developed to predict the destruction of estrogen compounds. Low solution temperature shows favorable destruction of estrogens. Increasing the fluid pressure is detrimental to reaction efficiency.     

Structural functions of taste in the sugar series: Binding characteristics of disaccharides

The previous finding that only one half of a disaccharide molecule binds to the taste receptor site is fully substantiated but the linkage and the sugar residues of the disaccharide are important. The study is extended to the field of bitterness and it is observed that binding on to the bitter receptor is analogous to that on to the sweet receptor. With reducing disaccharides, it is the non-reducing glycosyl unit that binds to the taste bud protein. Therefore, oligosaccharides constitute ideal models for this study despite their free anomeric centres.     

Enzymatic synthesis of novel disaccharides using disaccharide phosphorylases

A method for the synthesis of novel disaccharides was developed. It involved the following two steps. The first step consisted of two continuous reactions: the conversion of maltose to beta-D-glucose-1-phosphate and D-glucose by the phosphorolytic activity of maltose phosphorylase and the specific consumption of only D-glucose by incubation with glucose-consuming yeast cells. The second step involved the addition of an appropriate carbohydrate and its condensation with the remaining beta-D-glucose-1-phosphate by the synthetic activity of maltose phosphorylase or trehalose phosphorylase. Several factors affecting the yields of disaccharides were optimized. Using this method, five maltose-like derivatives and two trehalose-like derivatives were synthesized from maltose and the corresponding carbohydrates. Among these, 4-O-alpha-D-glucopyranosyl-L-fucopyranose (Glc(alpha1-4)Fuc) and alpha-d-glucopyranosyl alpha-D-fucopyranoside (Glc(alpha1-1alpha)Fuc) were purified, and identified by 1H NMR and 13C NMR.     

Thermal stability of catechin and epicatechin upon disaccharides addition

Influence of sucrose and trehalose addition on epimerisation and thermal degradation of catechin and epicatechin have been studied. Sucrose addition accelerated epimerisation of catechin and epicatechin at 80 and 100 °C. Addition of trehalose had protective effect on epimerisation of catechin and epicatechin. Considering thermal degradation, it was confirmed that thermal degradation of catechin and epicatechin follows the first‐order kinetics. Increasing the temperature causes shorter half‐lives of catechin and epicatechin. Addition of sucrose had negative effect on catechin stability. However, in samples with epicatechin, sucrose impact was temperature dependent. Trehalose addition had positive impact on preventing catechin and epicatechin degradation almost doubling the half‐life of studied compounds. Data presented in this study could help to predict chemical conversions of investigated phenolics in various food systems and to prolong their shelf life in thermally processed foods.     

Effects of mono- and disaccharides on the antimicrobial activity of bovine lactoperoxidase system

The effects of mono- and disaccharides on the antimicrobial activity of the lactoperoxidase (LPO) system against Salmonella Enteritidis were investigated. The results clearly reveal that most of the sugars inhibit the antimicrobial activity of the LPO system. The inhibitory potency varies depending on the structure of sugar. L-Fructose and D-allose were strongly inhibitive to the action of the LPO system, while sucrose was the weakest inhibitor. The decreased antimicrobial activity is due to the reduction of LPO catalytic activity by sugar. An inhibitory kinetic study showed the noncompetitive inhibitor. D-Allose and L-fructose yielded strikingly low K(i) values of 0.36 and 0.42 mM, respectively, while the K(i) values of the other sugars ranged from 1.37 to 3.60 mM. Since LPO activity is inhibited by the saccharides, the sugar content in food should be considered when the LPO system is applied to the preservation of food.     

铜基金属结合剂中锌的测定

文章报道了铜基金属结合剂中锌的含量测定的新方法。采用原子吸收分光光度法测定铜基金属结合剂中锌,不需分离基体铜,直接测定Zn。其工作曲线线性良好,标准偏差为0．0178。用于铜基金属结合剂中锌含量的测定,结果满意。     

Tiliroside, a glycosidic flavonoid, inhibits carbohydrate digestion and glucose absorption in the gastrointestinal tract

Scope Recent studies have reported that tiliroside, a glycosidic flavonoid, possesses anti‐diabetic activities. In the present study, we investigated the effects of tiliroside on carbohydrate digestion and absorption in the gastrointestinal tract. Methods and results This study showed that tiliroside inhibits pancreatic α‐amylase (IC₅₀ = 0.28 mM) in vitro. Tiliroside was found as a noncompetitive inhibitor of α‐amylase with K_i values of 84.2 μM. In male ICR mice, the increase in postprandial plasma glucose levels was significantly suppressed in the tiliroside‐administered group. Tiliroside treatment also suppressed hyperinsulinemia after starch administration. Tiliroside administration inhibited the increase of plasma glucose levels in an oral glucose tolerance test, but not in an intraperitoneal glucose tolerance test. In human intestinal Caco‐2 cells, the addition of tiliroside caused a significant dose‐dependent inhibition of glucose uptake. The inhibitory effects of both sodium‐dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2) inhibitors (phlorizin and phloretin, respectively) on glucose uptake were significantly inhibited in the presence of tiliroside, suggesting that tiliroside inhibited glucose uptake mediated by both SGLT1 and GLUT2. Conclusion These findings indicate that the anti‐diabetic effects of tiliroside are at least partially mediated through inhibitory effects on carbohydrate digestion and glucose uptake in the gastrointestinal tract.     

Synthesis of linoleoyl disaccharides through lipase-catalyzed condensation and their surface activities

Monolinoleoyl trehalose, maltose and cellobiose were synthesized by Candida antarctica lipase-catalyzed condensation in an organic solvent with a low water content. The use of a mixture of pyridine and tert-butanol as the reaction medium resulted in a high product concentration on the order of mmol/l for the synthesis of linoleoyl trehalose and maltose. The highest product concentration was achieved with the 0.4 volumetric fraction of pyridine. Linoleoyl cellobiose was also synthesized although its concentration was approximately one tenth the concentrations of linoleoyl trehalose and maltose. The surfactant properties of linoleoyl trehalose, maltose and cellobiose were measured. Among the esters, linoleoyl trehalose showed the strongest surface activity.     

Transfer of high-mannose-type oligosaccharides to disaccharides by endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae

Endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) has transglycosylation activity, and high-mannose-type oligosaccharides are transferred to suitable glycosides as acceptor substrates. The acceptor specificity of Endo-A-catalyzed transglycosylation toward various disaccharides was investigated. To identify an effective acceptor for the transglycosylation by Endo-A, the reaction was carried out using various disaccharides. Endo-A transferred high-mannose-type oligosaccharides more efficiently to beta-linked disaccharides (cellobiose, gentiobiose, sophorose, and laminaribiose) than to alpha-linked disaccharides (isomaltose, maltose, nigerose, kojibiose, and trehalose) as acceptor substrates. The transglycosylation products, (Man)6GlcNAc-Glc-beta-Glc, were more rapidly hydrolyzed than (Man)6GlcNAc-Glc-alpha-Glc. These results indicate that Endo-A recognizes the anomeric configuration of the acceptor substrates, and beta-linked glycosides are suitable for the synthesis of transglycosylation products.     

HPLC-ELSD同时分离检测食品中十种单糖、双糖和低聚果糖

为实现食品中木糖、果糖、葡萄糖、半乳糖、蔗糖、麦芽糖、乳糖、蔗果三糖、蔗果四糖、蔗果五糖等十种糖的同时分离检测,建立了以乙腈-水为流动相,NH2色谱柱分离,梯度洗脱,蒸发光散射检测器检测的分离检测方法;十种糖均在0.1～5mg/mL内具有良好的线性,线性相关系数在0.9901～0.9996之间;检出限均在0.1mg/mL以下,精密度RSD在1.71％～7.21％之间,回收率在97.91％ ～ 103.35％之间,结果较理想.本法高效、简单快速,可作为食品中以上十种糖同时分离检测的分析方法.     

高效液相色谱—蒸发光散射检测法测定发芽小麦中单糖和双糖

应用高效液相色谱-蒸发光散射检测法测定发芽小麦中果糖、葡萄糖、蔗糖及麦芽糖含量。样品经热水提取后,采用Kromasil NH2(250 mm×4.6 mm,5μm)柱分离,以乙腈–水(85∶15,V/V)为流动相,流速:1.5 ml/min;柱温为室温;进样量:20μl,进行定性定量分析。结果表明,该法具有灵敏度高、重现性、稳定性好、简便快速等优点,为测定发芽小麦中单糖和双糖提供准确、可靠分析方法。     

Evolution and kinetics of monosaccharides,disaccharides and α-galactosides during germination of lentils

The effect of light and seed rinsing during the germination of lentil seeds (Lens culinaris var. vulgaris, cultivar Magda-20) on the level of monosaccharides, disaccharides and α-galactosides (raffinose, ciceritol and stachyose) was investigated. The total soluble sugar content corresponded to about 9% of the mature seed weight, about 65% of which was α-galactosides. Germination brought about a large decrease in α-galactosides: 18% to 40% losses after 3 days and 100% after 6 days. However, glucose, which was not detected in ungerminated seeds, as well as fructose and sucrose gradually increased during germination. The content of α-galactosides decreased more rapidly when germinating seeds were given 6 h light per day, but under these conditions there was also a major reduction in the levels of fructose, glucose and sucrose. Seeds rinsed daily showed a greater reduction of α-galactosides and an increase in the levels of fructose, glucose and sucrose. When seeds were germinated for 10 days in the dark with daily rinsing, the content of α-galactosides decreased gradually during the first 4 days and they were not detected after 6 days. Under these conditions, fructose, glucose and sucrose, which represented about 3% of the mature seed weight, started increasing after day 2 and represented more than 13% of the germinated seed dry weight after 10 days.     

Antioxidant,anti-inflammatory and DNA scission inhibitory activities of phenolic compounds in selected onion and potato varieties

Processing of onion and potato produces a large amount of discards, mainly skins. This study compared the antioxidant activity of skin and flesh phenolics of selected onion (Pearl, Red, Yellow and White) and potato (Purple, Innovator, Russet and Yellow) varieties. All tests were carried out separately for the soluble and insoluble-bound phenolic constituents of onion and potato samples. The potency of the phenolic extracts in the inhibition of radical-induced DNA scission, human low-density lipoprotein (LDL) cholesterol oxidation and LPS-stimulated cyclooxygenase-2 (COX-2) expression in J774A.1 mouse macrophage cells were monitored. Results showed that the soluble extracts had a higher phenolic content and antioxidant activity than the insoluble-bound extracts in most of the assays. Both onion and potato phenolics exhibited notable inhibition of LDL cholesterol oxidation, DNA scission and COX-2 expression at concentrations as low as 5 μg/mL. Pearl onion skin and Purple potato peel phenolics exhibited the highest activities among the tested onion and potato varieties, respectively.     

Determination of the internal bond of particleboard and fibreboard

Tensile strength perpendicular to the surface is generally used as a measure of the internal bond of particleboard and fibreboard. This strength property cannot be used in structural strength calculations. Besides, determining the tensile strength perpendicular to the surface is troublesome. The object of this research was to find correlations between the tensile strength perpendicular to the surface and other strength properties and to detect a more easily determinable strength property for describing the internal bond of boards. The test material comprised 124 particleboards and 95 fibreboards from the standard production of Finnish factories. The following board properties were determined: density, moisture content during the tests, tensile strength perpendicular to the surface, shear strength, tension-shear strength, torsion-shear strength, torsion strength, and modulus of rigidity. The results show that torsion strength and torsion-shear strength correlate most strongly with the tensile strength perpendicular to the surface. Further investigations must thus be concentrated on developing a suitable method of determination for these strength properties.     

Formation of α-dicarbonyl fragments from mono- and disaccharides under caramelization and Maillard reaction conditions

Glyoxal, methylglyoxal and diacetyl were identified as reaction products from non-enzymatic browning of D-glucose (Glc), D-fructose (Fru), maltose and maltulose. The α-dicarbonyl compounds were quantified throughout the reaction. Monosaccharides formed more dicarbonyl fragments than disaccharides and Glc formed more than Fru. It is suggested that Fru tends to yield cyclic products rather than fragmentation products under the reaction conditions used. Furthermore, a mechanism for the fragmentation of disaccharides is proposed.     

Comparative study of postprandial glycaemia in type 2 diabetic patients after consumption of mono- and disaccharides and sweeteners

It was investigated the influence of mono- and disaccharides, sugar alcohols, honey, corn patoka and products with nutritive and nonnutritive sweeteners on dynamic of postprandial glycaemia in type 2 diabetic patients. After ingestion of 30 g fructose, blood glucose did not show a marked increase in comparison with sucrose or honey. After ingestion of 30 g sorbitol or isomalt, blood glucose curve was not significantly different. It was indicated that corn patoka in chewing candies with isomalt has a high hyperglycaemic effect whereas drink with nonnutritive sweeteners did not change blood glucose from fasting levels.     

金刚石砂带用酚醛树脂胶粘剂的初步改性研究

酚醛树脂是砂带生产的常用胶粘剂,但由于金刚石与普通磨料在性能上有很大的差别,金刚石与涂附层的粘结技术及其粘结剂本身的耐磨性、柔软性等很难解决,从而成为金刚石砂带发展的一个“瓶颈”。因此,必须在普通磨料砂带研究的基础上进行改性,才能得到性能优越的金刚石砂带。试验分别将4条不同添加剂和采用不同植砂工艺制成的砂轮进行测试,研究了偶联剂,植砂方式及金刚石等因素对砂轮质量的影响。