液相色谱法和液相色谱-串联质谱法测定荔枝中萘乙酸农药残留量

采用液相色谱要串联质谱法(LC/MS/MS)对荔枝中萘乙酸农药残留进行检测研究。结果表明:利用乙腈对荔枝(果肉、皮)中萘乙酸的提取,C18固相萃取柱净化,在LC/MS/MS上进行检测,荔枝中萘乙酸的回收率在86.8豫耀95.2豫之间,相对标准偏差为0.9豫耀3.1豫。该方法操作简便快递、准确可靠、重现性好。     

Semi-sweet biscuit making potential of soft wheat flour patent,middle-cut and clear mill streams made with native and reconstituted flours

The influence of patent, middle-cut and clear flour grades as native or reconstituted flour blends on both the rheological properties of the dough and the quality of semi-sweet biscuit (flour/sugar/fat/water ratio of 100/30/8/36) was studied. Moving from the central portion (patent) to the peripheral portion (clear) of the grain endosperm increased the dough hardness from 3.77 to 4.84 N, consistency from 19.3 to 25.5 N s, elongational viscosity from 4.13×10⁻⁵ to 5.54×10⁻⁵ Pa s, half-relaxation time from 0.45 to 0.59 s, but decreased the rate of relaxation from 4.51 to 3.09 s⁻¹ of the biscuit's dough produced with the native flours due to the wide variation in the physico-chemical properties of these fractions. Quantitatively, the fractionation/reconstitution procedure reduced moderately these rheological parameters, and the flour functionality could not be restored completely. Biscuits produced with the patent flour showed the largest length and lowest thickness, whilst the clear fraction led to production of denser biscuits with greater cohesion (mean tearing force) of the biscuit inner structure and also contain more grains or group of grains per unit of penetration (number of spatial ruptures). The biscuits made with the reconstituted flour fractions had almost equivalent dimensional characteristics, and excellent surface appearance, but were also darker in colour than their native flour counterparts.     

Genetic approach for the fast discovery of phenazine producing bacteria

A fast and efficient approach was established to identify bacteria possessing the potential to biosynthesize phenazines, which are of special interest regarding their antimicrobial activities. Sequences of phzE genes, which are part of the phenazine biosynthetic pathway, were used to design one universal primer system and to analyze the ability of bacteria to produce phenazine. Diverse bacteria from different marine habitats and belonging to six major phylogenetic lines were investigated. Bacteria exhibiting phzE gene fragments affiliated to Firmicutes, Alpha- and Gammaproteobacteria, and Actinobacteria. Thus, these are the first primers for amplifying gene fragments from Firmicutes and Alphaproteobacteria. The genetic potential for phenazine production was shown for four type strains belonging to the genera Streptomyces and Pseudomonas as well as for 13 environmental isolates from marine habitats. For the first time, the genetic ability of phenazine biosynthesis was verified by analyzing the metabolite pattern of all PCR-positive strains via HPLC-UV/MS. Phenazine production was demonstrated for the type strains known to produce endophenazines, 2-hydroxy-phenazine, phenazine-1-carboxylic acid, phenazine-1,6-dicarboxylic acid, and chlororaphin as well as for members of marine Actinobacteria. Interestingly, a number of unidentified phenazines possibly represent new phenazine structures.     

α and β-galactosidase activities and oligosaccharide content in peanuts

Thirty-three peanut cultivars were examined for their alpha-1,6 and beta-1,4 galactosidase activities and oligosaccharide contents along with proximate compositions. The average moisture, protein, fat, ash, and carbohydrate contents were: 4.9%, 26.6%, 43.1%, 2.3% and 23.1%, respectively. The corresponding coefficients of variation were: 5.2%, 10.1%, 7.2%, 7.8% and 15.7%, respectively. Raffinose and stachyose contents (%) ranged from 0.05 to 0.12 and 0.31 to 0.61, respectively. The specific activity (micromol product/min/mg protein) of crude preparation of alpha-galactosidase for the 33 cultivars ranged from 1.096 to 2.784 for the non-germinated seeds and from not being detected in some samples up to 2.432 for the germinated seeds; the mean values for non-germinated and germinated seeds were: 1.781 and 1.410, respectively. The specific activity of beta-galactosidase ranged from 0.101 to 1.727 in the non-germinated seeds and from not being detected in some samples up to 0.898 in the germinated seeds. Germination decreased the activity of both galactosidases significantly (p < or = 0.05).     

Fatty acid,amino acid,and trace mineral analyses of five weaning foods from Jos,Nigeria

Five plant-based weaning foods (WF) (Dietrend, Jot-M, Soy, Ang and Vic-T) locallyprepared in Jos, Nigeria were analyzed by gas-liquid chromatography,reverse-phase high performance liquid chromatography, and atomicemission spectrometry with inductively coupled plasma to determine theirfatty acid (FA), amino acid, and trace mineral contents, respectively.Results of these direct analyses were compared to expected values derivedfrom food composition tables prepared by the United States Department of Agriculture (USDA). Additionally, results were compared against recommendednutrient values, using breast milk as the standard for FA content andrecommended dietary allowances (RDA) for amino acid and mineral contents.The overall nutritional value of the five WF varied considerably and thequantities of particular nutrients determined by direct analysis differedmarkedly from those estimated using USDA food tables. Comparison of WFfatty acid composition relative to the RDA recommendations and a humanmilk standard revealed a much higher proportion of both linoleic (35–55wt%) and -linolenic acids (1%–7 wt%) relative to human milklipids (11%–12% and 0.8%–0.9% wt, respectively); however, the WFwere devoid of arachidonic acid and docosahexaenoic acid. Soy containedthe highest amounts of linoleic acid (59.7 mg/g) and -linolenicacid (7.46 mg/g) compared to the other four WF (10.2–41.0 and 0.35–3.18 mg/g, respectively). The linoleic acid/-linolenic acid ratio was within the recommended range (5:1 to 10:1) in only Jot-M (10:1)and Soy (8:1). Dietrend, Vic-T and Ang, containedlinoleic/-linolenic ratios of 12:1, 29:1, and 82:1, respectively.The Soy weaning food would provide the most protein (24.3 g/day), basedon an estimated daily intake of 65 g of weaning food by a normalsix-month-old infant, compared to Jot-M (11.9 g/day), Dietrend (11.7g/day), Ang (8.07 g/day) and Vic-T (7.26 g/day). The protein RDA forchildren up to 1 year of age is 13–14 g/day. Comparison of the mineralcontents of the WF to the RDAs for various minerals indicated that all fivewould provide suboptimal amounts of calcium (16 to 250 mg/day) andzinc (1.42 to 3.56 mg/day) compared to respective RDAs of400 mg/day and 5 mg/day.These data show that the Soy weaning food is an excellent source of linoleicacid and -linolenic acid, as well as being a good source of highquality protein. Jot-M and Dietrend provide useful amounts of the essentialFA; however, it is advisable to reevaluate the composition of Ang andVic-T to find ways to improve the linoleic/-linolenic ratio of eachand increase their total protein content. These results document theshortcomings of using published food composition tables based on foods inAmerica when devising weaning foods based on ingredients in another partof the world.     

美国大豆产量生理研究的进展

从籽粒生长调控的参与因互及其机理、源库关系在产量形成中的作用、全球气候变化对大豆生育和产量的影响以及冠层（群体）光合作用等方面综述了美国大豆产量生理研究进展。     

Changes in carbohydrate and nitrogenous components and amylase activities during germination of grain amaranth

Grain amaranth (Amaranthus hypochondriacus), Yercaud local variety, was soaked overnight and germinated for 192 h taking the soaked grains as the zero time (0 h) sample. The changes in the activities of - and -amylases, starch, sugar, protein and lysine contents during germination are reported. Activity of -amylase was high in the 0 h soaked grains, while -amylase activity was high in 72 h germinated grains. The joint action of the amylases resulted in a decrease of starch content from 0 to 192 h in germinated grains and an increase in total sugars during the initial period of germination.Protein nitrogen was found to decrease from 48 h to 192 h accompanied by an increase in free amino acid and non-protein nitrogen contents. Total lysine content was found to be increased by 31% in 24 h germinated grain amaranth. Protein fractionation of raw, soaked and 24 h germinated grain amaranth showed that the distribution of different types of proteins varied during germination of the grains. An increase of water soluble protein content was noticed in 24 h germinated grains.     

Comments on the importance of green vegetables

Green, especially leafy, vegetables are widely underesteemed because few horiticultural research institutes publish figures demonstrating that they can give unusually large annual yields of edible dry matter, including protein and carotene (provitamin A). It is also not realised that they supply many communities with as much protein as is supplied by fish, and that more communities used to eat them on that scale. Before leafy vegetables gain proper nutritional attention it will be necessary to convince consumers that they are not merely sources of vitamin C and minerals, or decorative adjuncts to a meal. It will also be necessary to persuade those who compile dietary and production statistics to separate leafy vegetables from other horticultural products which, although they may yield more profit per hectare, are of much less nutritive value.     

环氧胶／天然胶共混物中塑化剂的研究

在ＥＮＲ／ＮＲ共混物中，塑化剂ＴＢＥＰ、Ｄｉｏｌｐａｔｅ７０１７的平衡分配系数Ｋｄ随硫化程度的变化而变化，填充炭黑的共混物的Ｋｄ值减少，塑化剂起到降低ＥＮＲ相Ｔｇ和平衡两组份粘度的作用；ＮＲ／ＥＮＲ共混物能获得较优的减震性能和其他力学性能。     

On determination of chitin content in mushrooms

Nitrogen compounds constitute the greatest proportion of the dry weight of mushrooms. These nitrogen compounds are partly protein and partly non-protein. A modified Heneberg-Stohman's method was used to separate non-protein from protein nitrogen, as well as to determine raw fiber content in mushrooms, since the methods used previously for this purpose are time-consuming and complicated. Elemental analysis of crude fiber was performed to confirm the uniformity of isolated products. The content of total crude fiber (fungin) and the proportion of chitin and cellulose in it were determined. The chitin content of 15 species of field grown edible mushrooms was in the range of 1.87–6.93% of total dry mass and 34.51–67.72% of isolated fungin.