Evaluation of six insecticides against adults and larvae of Trogoderma granarium Everts (Coleoptera: Dermestidae) on wheat,barley, maize and rough rice

We evaluated the following six insecticides: cypermethrin, deltamethrin, pirimiphos-methyl, silicoSec, s-methoprene and spinosad, that are registered as grain protectants, against adults or larvae of the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) on wheat, barley, maize and rough rice. Three doses were tested: the half of the label dose, the label dose and the double label dose for each insecticide and mortality was assessed after 1, 3, 7 and 14 days (d) post exposure. For parental adults, progeny production was estimated after an additional period of 46 d of exposure. All tested insecticides were able to suppress T. granarium adults, even at the lowest dose. Pirimiphos-methyl and silicoSec were found to be most effective than the other insecticides, as these were the only ones that caused application resulted in 100% mortality at the 7-d exposure interval, at the half label or label dose. Conversely, the majority of the insecticides tested were found to be ineffective against T. granarium larvae. Pirimiphos-methyl was the only insecticide on which larval mortality reached 100% on all commodities tested and by far more effective than the other insecticides. For both adults and larvae, mortalities were generally higher on wheat and barley, than on rough rice and maize, for most of the combinations tested. Our findings indicate that the biological stage (i.e., adults or larvae) and the type of infected commodity should be seriously considered when insecticidal management strategies with cypermethrin, deltamethrin, pirimiphos-methyl, silicoSec, s-methoprene or spinosad are planned against T. granarium.     

Mechanism and kinetics of cyanogen chloride formation from the chlorination of glycine

Glycine is an important precursor of cyanogen chloride (CNCl)--a disinfection byproduct (DBP) found in chlorinated drinking water. To model CNCl formation from glycine during chlorination, the mechanism and kinetics of the reaction between glycine and free chlorine were investigated. Kinetic experiments indicated that CNCI formation was limited by either the decay rates of N,N-dichloroglycine or a proposed intermediate, N-chloroiminocarboxylate, CIN=CHCO2-. Only the anionic form of N,N-dichloroglycine, NCl2CH2CO2-, however, decays to form CNCl, while the protonated neutral species forms N-chloromethylimine. At pH > 6, glycine-nitrogen is stoichiometrically converted to CNCI, while conversion decreases at lower pH due to the formation of N-chloromethylimine. Under conditions relevant to drinking water treatment, i.e., at pH 6 to 8 and with free chlorine in excess, a simplified rate expression for the concentration of glycine-nitrogen converted to CNCl, [CNCl]f, applies: dt/d[CNCl]f = k2*[Cl2-Gly](T,o)exp(-k2*t) where [Cl2-Gly]T,o is the initial concentration of total N,N-dichloroglycine, k2* is the first-order decay constant for CIN=CHCO2-, k2*(s(-1)) = 10(12)(+/-4) exp(-1.0(+/-0.3) x 10(4)/T), and T is the absolute temperature in K. Kinetic expressions for d[CNCl]/dt when free chlorine is in excess, however, must also account for the significant decay of CNCl by hypochlorite-catalyzed hydrolysis, which has been characterized in previous studies. Although CNCl formation is independent of the free chlorine concentration, higher chlorine concentrations promote its hydrolysis.     

Surface Tension and Foamability of Protein and Surfactant Solutions

Decay of surface tension of protein solutions obeyed an empirical equation for first-order decay during the first 10 to 60 min after formation of a new surface. First-order rate constants (k) for surface tension decay of protein solutions, calculated at various protein concentrations, were closely correlated with “foaming power” (foamability) of the solutions. A similar correlation between “foaming power” and k values was also observed for low molecular weight surfactant solutions. The k values for low molecular weight surfactant solutions were lower than those for protein solutions with similar “foaming power” to surfactant solutions. Equilibrium surface tensions of low molecular weight surfactant solutions were closely correlated with their “foaming power,” though such correlation was not found in the case of protein solutions.     

Ultraviolet inactivation kinetics of Escherichia coli and Yersinia pseudotuberculosis in annular reactors

Terrorist threats have precipitated the need for information on the ultraviolet (UV) resistance of potential biothreat agents in food processing, such as Yersinia pestis. The objective of this study was to characterize the resistance of the Yersinia species to UV treatment using a single-lamp annular UV reactor. A novel method is proposed to measure the inactivation kinetics of Yersinia pseudotuberculosis, a surrogate of Y. pestis. This proposed method can overcome the disadvantages of the traditional collimated beam approach for liquids with high absorptive properties, such as liquid foods. As a reference, an inactivation rate of Escherichia coli K12 in caramel model solutions was measured first. Both first-order and series-event inactivation models were used to fit UV inactivation data. For the series-event model, an inactivation constant of k(SE)= 0.675 cm(2)/mJ and threshold n= 4 were obtained for E. coli K12 with the coefficient of determination R(2)= 0.987 and the standard deviation of log(10) reductions sigma(y)= 0.133. For Y. pseudotuberculosis, k(SE)= 0.984 cm(2)/mJ and n= 3 were obtained with R(2)= 0.972 and sigma(y)= 0.212. In contrast, for the first-order inactivation model, the first-order inactivation constant k(1)= 0.325 cm(2)/mJ with R(2)= 0.907 and sigma(y)= 0.354 was found for E. coli; and k(1)= 0.557 cm(2)/mJ with R(2)= 0.916 and sigma(y)= 0.402 was obtained for Y. pseudotuberculosis. Based on R(2), sigma(y), and the maximum absolute and relative errors, the series-event inactivation model describes the UV inactivation kinetics of Y. pseudotuberculosis and E. coli better than the first-order model. It is apparent that Y. pseudotuberculosis is less resistant to UV light than E. coli K12.     

The influence of storage practices on aflatoxin contamination in maize in four agroecological zones of Benin, west Africa

Aflatoxin level in 300 farmers’ stores in four agro-ecological zones in Benin, a west African coastal country, were determined over a period of 2 years. At sampling a questionnaire was used to evaluate maize storage practices. Farmers were asked what storage structure they used, their storage form, storage period, pest problems in storage and what was done against them. Beninese farmers often changed their storage structures during the storage period, transfering the maize from a drying or temporary store to a more durable one. Most of the farmers complained about insects damaging stored maize. Often, storage or cotton insecticides were utilized against these pests. Regression analysis identified those factors that were associated with increased or reduced aflatoxin.

Maize samples in the southern Guinea and Sudan savannas were associated with higher aflatoxin levels and the forest/savanna mosaic was related to lower toxin levels. Factors associated with higher aflatoxin were: storage for 3–5 months, insect damage and use of Khaya senegalensis-bark or other local plants as storage protectants. Depending on the agroecological zone, storage structures that had a higher risk of aflatoxin development were the “Ago”, the “Secco”, the “Zingo” or storing under or on top of the roof of the house. Lower aflatoxin levels were related to the use of storage or cotton insecticides, mechanical means or smoke to protect against pests or cleaning of stores before loading them with the new harvest. Fewer aflatoxins were found when maize was stored in the “Ago” made from bamboo or when bags were used as secondary storage containers.     

Efficacy of six grain protectants applied alone or in combination against three species of coleoptera

Laboratory experiments were carried out to establish whether there were synergistic or antagonistic interactions in combination treatments of certain grain protectants. Six protectants were applied alone, or in combination, against Rhyzopertha dominica (F.) in stored maize and wheat, and Sitophilus oryzae (L.) and Tribolium castaneum (Herbst) in stored wheat. There were four organophosphorus (OP) insecticides (fenitrothion, chlorpyrifos-methyl, pirimiphos-methyl and methacrifos), one juvenile hormone analogue (methoprene) and one synergised pyrethroid (deltamethrin+piperonyl butoxide); and combination treatments consisted of either methoprene or synergised deltamethrin plus an OP insecticide. Based on the levels of control of adult progeny and periods of protection, there were no interactions between protectants. The results show that there is no need to alter field application rates to compensate for antagonism or to take advantage of synergism. They also support the view that application rates for combination treatments can be estimated from experiments on individual protectants using target species or strains.     

Biodegradation of synthetic base fluid surrogates in Gulf of Mexico sediments under simulated deep-sea conditions

In this study, an anaerobic marine biodegradability test was adapted to study the fate of synthetic base fluid (SBF) surrogates, ethyl oleate and tetradecene, by deep-sea microorganisms. Sediment samples from hundreds of meters deep in the Gulf of Mexico were incubated at low temperatures (4 degrees C) and high hydrostatic pressure in steel vessels. Stimulation of indigenous microbial communities to SBF biodegradation was evident in the fact that the rate of removal of ethyl oleate was greater in sediments that had some previous exposure to SBF (first-order decay coefficient kof -0.22 +/- 0.02 week(-1)) compared to unexposed control sediments (first-order decay coefficient k of -0.11 +/- 0.02 week(-1)). When sulfate-linked tetradecene degradation occurred within the test period, the activity could also be modeled as a first-order decay following an initial lag phase, with an average decay coefficient of k = -0.05 +/- 0.01 week(-1). This study also revealed that the degradation of SBF surrogates by microorganisms collected from deep-sea sediments was not significantly effected by the hydrostatic incubation pressure.     

减压处理鲜切西兰花的货架期预测模型构建

将鲜切西兰花减压处理36 h后,分别置于273 K、278 K、283 K、288 K、293 K五个不同温度下贮藏,定期检测Vc含量的变化。应用化学反应动力学的零级反应和一级反应两种模型分别对Vc的变化趋势进行拟合,确定了不同温度下Vc的变化速率k,结果表明:Vc变化速率k随温度的上升而增大,以一级反应为模型的拟合方程优于以零级反应为模型的拟合方程。应用Arrhenius方程,进一步确定了温度与Vc变化速率k之间的关系式,由此构建了2种货架期预测模型。最后结合感官评价对2种货架期模型进行准确性评估,发现:基于一级反应建立的货架预测模型SL1的准确度较高,平均相对误差为7.94%,R2=0.9986,模型参数为:指前因子k0=-3.19×1020,活化能Ea=118762.49。此模型SL1可有效估测273 K到293 K范围内任意温度下,减压处理鲜切西兰花的货架期。     

Lack of influence of extracellular polymeric substances (EPS) level on hydroxyl radical mediated disinfection of Escherichia coli

Photolysis of nitrate, a prevalent constituent in agriculturally impacted waters, may influence pathogen attenuation in such systems through production of hydroxyl radical ((?)OH). This study focuses on the efficacy of (?)OH generated during nitrate photolysis in promoting E. coli die-off as a function of extracellular polymeric substances (EPS) coverage. EPS levels of four E. coli isolates were systematically altered through a sonication extraction method and photochemical batch experiments with a solar simulator examined isolate viability loss as a function of time in nitrate solutions. E. coli viability loss over time exhibited two regimes: an initial induction time, t(s), with little decay was followed by rapid exponential decay characterized by a first-order disinfection rate constant, k. Increasing steady-state (?)OH concentrations enhanced E. coli viability loss, increasing values of k and decreasing t(s) values, both of which were quantified with a multitarget bacterial disinfection model. Notably, at a given steady-state (?)OH concentration, values of t(s) and k were independent of EPS levels, nor did they vary among the different E. coli strains considered. Results herein show that while (?)OH generated via nitrate photolysis enhances rates of disinfection in surface water, the mechanism by which (?)OH kills E. coli is relatively insensitive to common bacterial variables.     

Formation of Heterocyclic Amines in a Meat Juice Model System

Bovine meat juice was used as a model system to examine the kinetics of the formation of heterocyclic amines. The formation was examined at temperatures between 100 and 225°C for 0.5-180 min. Heated samples were subjected to solid-phase extraction and HPLC analysis. IQx, MeIQx, 7,8-DiMeIQx, 4,8-DiMeIQx, PhIP, harman and norharman were identified. The formation of the IQx derivatives and PhIP followed a first-order model C_t=B(1–e^k1(t1-t0), and the temperature dependence followed the Eyring equation k=k_bT/he^ΔS/Re-^ΔH/RT. The parameters in the first-order model and the Eyring equation could be estimated from our data. The degradation of heterocyclic amines at high temperatures was analyzed and the products were found to be less mutagenic.     

连续相变萃取灵芝多糖动力学球状模型的建立及其结构特征

根据中草药浸提机制和非稳态扩散理论对灵芝多糖(GLP)的连续相变萃取过程动力学进行研究,研究不同温度、流速和时间下GLP传质动力学,并对多糖结构特征进行分析。以灵芝子实体为原料,采用连续相变萃取技术得到GLP,基于Fick第二定律建立GLP溶出动力学球状模型方程并研究了萃取过程的热力学特性。利用高效凝胶渗透色谱法(HPGPC)研究多糖分子量分布、傅里叶变换红外光谱(FT-IR)对多糖官能团结构进行分析及扫描电子显微镜(SEM)观察多糖形态结构。最佳萃取工艺条件为:温度为373.15 K、流速为28 L/h,时间为190 min,在此条件下GLP得率为2.04%。动力学球状模型方程为ln[(C_∞-C)/C_∞]=π²Dt/R²+ln(π²/6),速率常数k、相对萃余率y=(C_∞-C)/C_∞及半衰期方程y=-7.440 x+2864.4等动力学参数,试验数据与动力学模型计算值吻合良好(R²>0.94),萃取过程符合一阶扩散动力学模型。HPGPC结果表明GLP分子量分布范围为1.35×10³~2.26×10⁷ Da。FT-IR结果表明GLP为β-吡喃型多糖,SEM显示GLP由碎片状聚集体所组成,呈现出褶皱状。该动力学模型可为灵芝多糖连续相变萃取工艺条件优化以及深层次研究奠定理论基础。     

Formate ion decomposition in water under UV irradiation at 253.7 nm

Formate ion (HCO2-) occurs in natural waters as a result of photooxidation of humic substances. Under UV irradiation, as applied in water purification (253.7 nm), formate ion decomposed following split-rate pseudo-zero-order kinetics (k1 and k2 are initial and final rate constants, respectively). In the presence of dissolved oxygen (DO), it was found that (a) k1 < k2, (b) k1 and k2 increased with initial formate ion concentration ([HCO2-]0 = (1.73-38.3) x 10(-5) mol L(-1)) and absorbed UV intensity (Ia = (1.38-3.99) x 10(-6) mol quanta L(-1) s(-1)), and (c) k1 and k2 were relatively insensitive to initial pH (pHo = 5.41-8.97) in buffer-free solutions. Both rate constants decreased with increasing carbonate alkalinity ((0-1.0) x 10(-3) mol L(-1)) and k1 was virtually unchanged in phosphate buffer at pH0 between 5.25 and 9.92. Carbonate buffer lowered the rate of formate ion decay, possibly due to scavenging of OH* radicals. Initial rate constant k1 slightly increased with temperature (15-35 degrees C), while k2 remained unchanged. The reaction pH increased rapidly during irradiation of buffer-free NaHCO2 solution to approach an equilibrium level as [HCO2-] reached the method detection level (MDL). The pH profile of buffer-free formate ion decay was estimated using closed-system equilibrium analysis. DO utilization during UV irradiation was 0.5 mol of O2/mol of HCO2-, while nonpurgeable organic carbon (NPOC) measurements on kinetic samples closely followed the HCO2- profile, thus strongly suggesting the transformation of HCO2- -C to CO2 in the presence of DO. In DO-free water, k1 > k2 was observed. Furthermore, k(1,DO FREE) > k(1,DO) (k(1,DO) = k1) and k(2,DO FREE) < k(2,DO) (k(2,DO) = k2). The effect of dual acid solutions on HCO2- decay was examined in a mixture of NaHCO2 and sodium oxalate (Na2C2O4). HCO2- decomposed readily until [HCO2-] approximately equal to MDL but at a lower rate than in buffer-free HCO2- solutions, while C2O4(2-) remained virtually unchanged. C2O4(2-) decay commenced following near complete conversion of HCO2-.     

淀粉的慢消化性能与酶水解速率研究

研究了体外模拟条件下不同淀粉中营养片断,同时建立了酶水解动力学方程来探讨慢消化性能与酶水解速率的关系。结果表明,相比马铃薯与绿豆淀粉,玉米、蜡质玉米、小麦、糯米、大米等谷物淀粉属于理想的慢消化淀粉,它们的酶动力学水解速率小于1h-1,而马铃薯与绿豆淀粉的水解速率大于1h-1。淀粉的水解过程的反应动力学速率比Englyst法更能准确反映淀粉的消化性能。     

Water-absorption rate equation of rice for brewing sake

This study was undertaken to analyze the kinetics of water absorption and to derive an equation for the rate at which water is absorbed by rice for brewing sake. We used two rice varieties: Gin-oumi, commonly used as a staple food, and Gohyakumangoku, a variety used particularly for brewing sake. The water-absorption rate equations of Gin-oumi and Gohyakumangoku were postulated based on the following equations. For Gin-oumi (water content, 11.5%), dx/dtheta=k(1-x)(n), n=1, k=(2 x 10(-9))exp(0.0604 x (t+273.15)). For Gohyakumangoku (11.5%), dx/dtheta=k(1-x)(n)(x+a), n=1, a=0.29, k=(2 x 10(-8))exp(0.0534 x (t+273.15)). Here, x, theta (min), and t ( degrees C) are the water absorbing ratio, time, and temperature, respectively. The result shows that the values of the temperature-dependence parameter k (min(-1)), as well as its curves, are different; a typical rice grain has a monotonically smooth curve, whereas that suitable for sake brewing has an S-shaped curve.     

Some factors influencing the syneresis of bovine, ovine, and caprine milks

The influence of the species, fat, curd incubation temperature (25, 30, and 35 degrees C), heat treatment of milk (70 degrees C for 5 or 30 min), and milk pH on the initial volume drained, syneresis rate, and the loss of proteins in drainage was studied. The volume drained as a function of the curd incubation time (up to 60 min) was adjusted to a first-order kinetic reaction. The k values (drained rate) and the initial volume obtained applying the equation were compared to establish the possible influence of the studied factors. In general, for all the factors studied, the syneresis rate of curd from caprine and ovine milk did not differ from those described previously in the literature for the curds from bovine milk. However, for each studied factor the pattern of syneresis rate was significantly different among the species in most of the experiments.     

Rheological Characterization of Low Fat Sesame Paste Blended With Date Syrup

In this paper, the time-dependent flow behavior of reduced fat sesame paste with date syrup were assessed using Brookfield rotational viscometer as a function of fat substitutes (guar gum, xanthan, and starch) at three levels and shearing time. Two models were used to predict the time-dependent behavior, known as, first-order stress decay with a zero equilibrium stress and Weltman models. It was found that time-dependent behavior of samples was adequately fitted with these models. All blends exhibited the thixotropic behavior and thixotropy of samples increased with increasing shear rate. For Weltman model, the A and B constants appeared in the range of 189.2–730.6 Pa and 0.090–1.571 Pa, respectively. While for first-order stress decay model, the initial shear stress (τ₀) was in the range of 197–794 Pa, and the breakdown rate constant (K) varied in the range of 0.002–0.018 s^?1. The presence of fat substitutes generally resulted in an increase of viscosity and thixotropy of blends in comparison with the blank.     

基于数字图像处理技术糙出白率和碾白率检测

通过扫描获取不同碾白时间下的大米图像,提取大米图像信息,分析大米图像信息与糙出白率和碾白率之间的相关性。结果表明:B平均值同糙出白率、H平均值同碾白率的相关系数较高,分别为-0.984 6、-0.986 1;然后建立B平均值同糙出白率、H平均值同碾白率的回归方程,分别为y=-0.302 5x+135.733,R2=0.965 6;y=-0.132 9x+105.401,R2=0.968 9。用建立的回归方程预测糙米糙出白率和碾白率,通过F检验和t检验表明,预测的糙出白率和碾白率与实际检测值是一致的.     

Insecticidal potential of zeolite formulations against three stored-grain insects,particle size effect,adherence to kernels and influence on test weight of grains

Laboratory studies were conducted in order to evaluate the insecticidal potential of three commercially available zeolite formulations against adults of Sitophilus oryzae, Tribolium confusum and Oryzaephilus surinamensis in wheat. For each zeolite formulation, three particle size levels were tested, i.e. 0–50, 0–150 and 0–500 μm. Zeolites were applied at three dose rates, 250, 500 and 1000 ppm, and insect mortality was assessed after 2, 7, 14 and 21 d of exposure. After the final mortality count, dead and alive insects were removed and offspring numbers were determined following an additional period of 65 d. In another series of laboratory bioassays, the effect of zeolite application on the test weight of wheat, maize and barley, as well as the adherence of zeolite particles to wheat, maize, barley and rice kernels was also measured. Oryzaephilus surinamensis was the most susceptible species to zeolite application, regardless of the zeolite formulation, dose and particle size level tested, whereas T. confusum was the most tolerant. No significant differences in efficacy were recorded among the three tested zeolite formulations. At the same time, particle size did not affect zeolite efficacy, at least for the particle size levels tested. All zeolites caused a significant reduction on the test weight of the treated grains. Moreover, zeolite particles showed different adherence among wheat, maize, barley and rice kernels. The results of the present study indicate that zeolites can be used with success as grain protectants, but there is a considerable effect on some physical properties of the grains. This information aims to encourage further evaluation of zeolites as grain protectants.     

超高压处理条件下的虾仁品质变化动力学

超高压技术是一种新型的食品非热加工技术。为掌握不同压力对凡纳滨对虾虾仁品质的影响规律,采用动力学方法建立虾仁品质变化的动力学模型,研究虾仁品质变化的动力学特性;通过动力学方程拟合,确定了虾仁品质在零级或一级模型中的动力学反应速率常数k和指数递减时间D值。研究表明:超高压处理压力和时间对虾仁的质量损失、水分含量、硬度、pH、红度a*、黄度b*值均有显著影响(p<0.05);不同压力条件下虾仁的质量损失、硬度、黄度值b*的变化遵循零级反应动力学,水分含量和pH的变化遵循零级反应动力学或一级反应动力学,红度a*值的变化遵循一级反应动力学模型。该研究结果可为预测和控制超高压加工虾仁品质提供参考。      

Atmospheric chemistry of 2-ethoxy-3,3,4,4,5-pentafluorotetrahydro-2,5-bis[1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl]-furan: kinetics, mechanisms, and products of Cl atom and OH radical initiated oxidation

Smog chamber/FTIR techniques were used to study the atmospheric chemistry of the title compound which we refer to as RfOC2H5. Rate constants of k(Cl + RfOC2H5) = (2.70 +/- 0.36) x 10(-12), k(OH + RfOC2H5) = (5.93 +/- 0.85) x 10(-14), and k(Cl + RfOCHO) = (1.34 +/- 0.20) x 10(-14) cm3 molecule(-1') s(-1) were measured in 700 Torr of N2, or air, diluent at 294 +/- 1 K. From the value of k(OH + RfOC2H5) the atmospheric lifetime of RfOC2H5 was estimated to be 1 year. Two competing loss mechanisms for RfOCH(O*)CH3 radicals were identified in 700 Torr of N2/O2 diluent at 294 +/- 1 K; decomposition via C-C bond scission giving a formate (RfOCHO), or reaction with 02 giving an acetate (RfOC(O)CH3). In 700 Torr of N2/O2 diluent at 294 +/- 1 K the rate constant ratio k(O2)/k(diss) = (1.26 +/- 0.74) x 10(-19) cm3 molecule(-1). The OH radical initiated atmospheric oxidation of RfOC2H5 gives Rf0CHO and RfOC(O)CH3 as major products. RfOC2H5 has a global warming potential of approximately 55 for a 100 year horizon. The results are discussed with respect to the atmospheric chemistry and environmental impact of RfOC2H5.