Degradation of acephate and its metabolite methamidophos in rice during processing and storage

The degradation of acephate and its metabolite methamidophos during different stages of commercial processing, homing processing, and storage was assessed. Residues were determined by a simple gas-chromatographic method using a flame photometry detector. Acephate and methamidophos mostly remained in rice hull fractions, and hulling significantly reduced acephate and methamidophos in rice. Commercial processing caused the loss of 86% of acephate and 35.9% of methamidophos from rough brown rice to polished rice, whereas home processing caused the loss of 83.9% of acephate and 70% of methamidophos from polished rice to cooked rice. Washing for 5, 15, and 30 min (with tap water, 0.9% NaCl, and 0.1% Na₂CO₃) caused an average loss in the range of 9.8%-35.3% of acephate and 9.7%-45.2% of methamidophos. Extending washing time and adding a small amount of soda into the washing solution can efficiently eliminate acephate and methamidophos. The stability of acephate and methamidophos in polished rice was studied at different storage intervals, from 7 to 42 days at ambient temperatures (25 °C). Methamidophos was found to be more persistent than acephate.     

Extracellular enzyme production and enterotoxigenic gene profiles of Bacillus cereus and Bacillus thuringiensis strains isolated from cheese in Turkey

The aim of the present study was to investigate the biochemical characteristics, extracellular enzyme production and enterotoxigenic genes contents of 6 Bacillus cereus and 22 Bacillus thuringiensis strains, isolated from 100 cheese samples in Turkey. Crystal morphologies of B. thuringiensis strains were found either spherical (n = 12) or spherical and irregular-shaped (n = 10) by phase contrast microscopy. B. cereus and B. thuringiensis strains were found to produce extracellular enzymes, respectively: gelatinase (83% and 91%), DNase (83% and 77%), lecithinase (83% and 95%), protease on skim milk agar (100% and 100%), protease on milk agar (100% and 91%), protease on casein agar (83% and 77%), xylanase (100% and 45%), and cellulase (0% and 41%), and amylase (83% and 27%). All of the strains, except for Bt-D1, hydrolyzed Tween 20 (96%), but not Tween 80 or tributyrin. Pectinolytic activity was obtained to be the least frequent (4%). PCR analysis showed that all strains contained nheA, nheB, nheC and hblD genes. The hblA and hblC genes were present in 2 and 4 of B. thuringiensis strains, respectively. The bceT gene was detected in 1 B. cereus and 9 B. thuringiensis strains. The entFM gene was detected more frequently in B. thuringiensis (82%) than in B. cereus strains (50%). To our knowledge, this is the first report about the isolation and identification of enterotoxigenic B. cereus and B. thuringiensis strains from cheese samples in Turkey.     

Inhibition of spoilage and toxigenic Bacillus species in dough from wheat flour by the cyclic peptide enterocin AS-48

Enterocin AS-48 was tested against rope-forming Bacillus subtilis CECT 4002 and Bacillus licheniformis CECT 20, as well as on Bacillus cereus and Bacillus pumilus strains in broth and in experimental dough from wheat flour. Vegetative B. subtilis cells in liquid broth were rapidly inactivated by AS-48 (7 AU/ml). In wheat dough, higher bacteriocin concentrations of 14 and 23 AU/g were required for inactivation of B. subtilis vegetative cells and endospores activated to germinate, respectively. B. cereus LWL1 and B. licheniformis CECT 20 were inactivated by AS-48 (14 AU/g) in doughs stored at 22 °C much faster compared to doughs stored at 10 °C. Strains of Bacillus pumilus were partially inactivated in dough by bacteriocin addition (14 AU/g). Results from this study indicate that enterocin AS-48 can reduce the populations of spoilage and potentially-toxigenic bacilli in wheat dough, decreasing the risks for spoilage and food intoxication.     

Investigation of the effects of food constituents on Bacillus subtilis reduction during high pressure and moderate temperature

Our published results and our studies for optimization of process conditions to inactivate Bacillus subtilis by high hydrostatic pressure and mild heat using response surface methodology indicated that the optimum process parameters for a six-log-cycle reduction of B. subtilis were obtained as temperature, 46 °C; pressure, 479 MPa; and pressure holding time, 14 min. Based on the results, response surface methodology (RSM) was employed in the present investigation, the effects of food constituents like soybean protein, soybean oil, sucrose, and pH of food matrix on the B. subtilis reduction during high pressure and moderate heat was studied, and a quadratic polynomial predictive model for the effects of food constituents and pH of food matrix on B. subtilis reduction during high pressure and moderate heat was built with RSM accurately. The experimental results showed that the efficiencies of B. subtilis reduction in milk buffer and food matrix designed in the present work, under the condition of high pressure treatment process parameters described above, had some differences. The soybean protein (P < 0.0001), sucrose (P < 0.0001), and pH (P = 00006) significantly affected reduction of B. subtilis. The effect of soybean oil on reduction of B. subtilis was not significant (P = 0.8363). The adequacy of the predictive model equation for predicting B. subtilis reduction in food matrix by high pressure and moderate heat was verified effectively using experimental test date that was not used in the development of the model.     

Effect of high pressure homogenization applied individually or in combination with other mild physical or chemical stresses on Bacillus cereus and Bacillus subtilis spore viability

High pressure homogenization (HPH) has been proposed as an effective alternative to high hydrostatic pressure in the continuous sanitization of fluid food systems. In this study, we evaluated the influence of HPH treatment, applied individually (one, two or three cycles) or in combination with other mild physical or chemical stresses (mild heat treatment H₂O₂ and low pH), on the capability of Bacillus cereus and Bacillus subtilis spore, suspended in sterilized double distilled water, to form colonies. Although plate count only slightly decreased in all the strains when one cycle of HPH at 150 MPa was applied alone, the spores released significant levels of dipicolinic acid (up to 28%) that could indicate a possible disruption of spore layers. Three consecutive cycles of HPH determined high reduction of colony count (about 5 log CFU/ml) and high DPA release (52%). Among the stress conditions applied, it was observed that only the thermal shock after one HPH cycle reduced the colony count of 2.3 log CFU/ml and induced a DPA release up to 57%.These results suggested HPH as a novel application for B. cereus and B. subtilis control in fluid foods.     

The antimicrobial activity of donkey milk and its microflora changes during storage

The antimicrobial activity of donkey milk was initially scanned against nine microorganisms using agar diffusion assay, and was further investigated via in situ inhibition by monitoring the growth of Salmonella choleraesuis (CGMCC 1.1859) and Shigella dysenteriae (CGMCC 1.1869) in it. The changes of microflora of donkey milk during prolonged storage at 4 and 20 °C were also studied. The results of the agar diffusion showed that S. choleraesuis and S. dysenteriae were the most sensitive strains towards the antimicrobial activity of donkey milk. In situ test revealed that the donkey milk exerted a definite bactericidal activity against S. dysenteriae and the viable counts decreased to below detectable level in a 1-ml sample at 20 °C. In the microbiological flora analysis, initial raw donkey milk contained a low microbial content. At 20 °C, lactic acid bacteria, coliforms and fungi grew well in donkey milk to give a total number of 6.66 log cfu/ml, 5.88 and 2.95, respectively, after 24 h storage. At 4 °C, no significant changes of microflora were observed after 96 h except coliforms which gave an 1 log increase.     

油井气液两相流的温度与压力耦合研究

运用热力学、传热学以及两相流理论,对油井稳定连续生产时的传热过程进行了理论分析,建立了数学模型,并运用数学方法对该模型进行了求解,该模型综合考虑了井筒的径向传热,不同环空传热介质及地层的热物理性质沿井深的变化,环空中流体的对流换热,辐射以及传热,焦耳-汤姆逊系数以及液相的体积膨胀系数。采用该井筒温度分布计算模型为依据,借鉴均质模型的井筒压力求解方法计算井底流压。     

Changes in antioxidant flavonoids during freeze-drying of red onions and subsequent storage

The aim of this study was to elucidate the effect of the freeze-drying process and storage on onion flavonoids content. Major flavonols of a mature red onion bulb were confirmed as quercetin derivatives (3,4′-O-diglucoside (Qdg) and 4′-O-monoglucoside (Qmg)) using a combination of chromatographic comparisons, UV–visible spectra and scientific literature data. These two components account for about a 93% of the total flavonols (334 ± 60 mg Q kg?¹, fresh weight), and are the main responsible for the IC50 antioxidant activity of 15.84 ± 3.73 g/kg. The remaining flavonol fraction (approx. 7%) comprises up to 8 different components of which quercetin-3-O-glucoside and isorhamnetin-4-glucoside are prominent members although each contribute less than 3% of the total flavonol fraction; instead, quercetin represents less than 1% of total flavonols. In this red onion, eight anthocyanins (which represent less than 1% of total flavonols) were also found at a total level of 2.1 ± 0.05 mg C3g kg?¹ (fresh weight). Anyway, 4 of them (cyanidin 3-glucoside (C3g) > cyanidin 3-(6′′-malonylglucoside) (C3,6mg) > cyanidin 3-(6′′- malonyl-laminaribioside) (C3,6mlmb) > cyanidin 3-laminaribioside (C3lmb)) account for the 95% of total anthocyanins. Freeze-drying process concludes in an increase in the extraction of flavonoids up to a 32% for flavonols and 25% for anthocyanins. Freeze-dried onion powder storage at room temperature, in dark, in air- and water-tight glass bottles for up to 6 months was keeping rather stable all flavonoids.     

Upland rice vinegar vapor inhibits spore germination,hyphal growth and aflatoxin formation in Aspergillus flavus on maize grains

The efficacy of vapor-phase (VP) upland rice vinegar (URV) was investigated as a bio-fumigant for maize, to reduce consumer health risks associated with spore and toxin formation by Aspergillus flavus. Complete reduction of mycelial growth occurred with in vitro VP exposure to URV (containing 0.0017 mmol/L acetic acid) or with VP exposure to pure acetic acid (PAA) (containing 0.0023 mmol/L acetic acid). No significant differences were observed between the two materials after 90 min exposures. Using gas chromatography-mass spectrometry (GC-MS), URV vapor was shown to contain volatiles having antifungal activities. These are identified as isoamylalcohol, 1-butanol, 3-methyl-, acetate and β-phenylethyl acetate. It is suggested these volatiles increase the antifungal effectiveness of URV. Exposure to VP-URV (containing 0.0043 mmol/L AA) for 5 h completely eliminated viable spores of A. flavus on maize seeds (23% moisture content) previously inoculated with 4.43 ± 0.28 log spores/g). At the same time, aflatoxin production decreased, as VP-URV exposure increased. Hence, VP-URV is shown to be an effective control agent for A. flavus mycelial growth and aflatoxin formation on maize, so effectively reducing the potential for consumer health risks due to this widespread fungus.     

欧美大型钢制低温储罐抗震设计方法对比分析

以欧美标准中的单包容与全包容低温储罐中的钢制储罐抗震设计方法为分析对象,从抗震设防水准与目标、抗震设计反应谱以及抗震设计准则如地震作用调整系数、阻尼比、载荷组合、抗震许用应力、抗倾覆与滑移、晃动波高等方面进行分析对比,为欧美低温储罐抗震设计方法的工程应用提供参考。为实现抗震设防目标以及与该国(区域)建筑抗震以及荷载标准体系协调,欧美低温储罐抗震各设计准则均存在一定的差异,工程设计时应合理应用以避免安全隐患。     

储罐VOCs来源及治理措施

VOCs对人体和区域环境会产生一定危害,石油化工企业的轻质油储罐区是VOCs的主要来源,必须对储罐区油气排放进行治理.文中根据储油罐区VOCs产生的原因进行分析,对比不同的处理方法,结合石油化工企业的特点提出了"低温柴油回收+碱液吸收+催化氧化"的处理方法,对处理装置进行评价,通过数据估算,该装置运行后能够产生良好的经...     

Temperature increase of foods in car trunk and the potential hazard for microbial growth

This study assessed the potential microbial hazard posed by temperature increases on refrigerated and frozen food stored in car trunk exposed to sunlight. The internal temperatures in the trunk and of food items (egg, milk, tofu, fresh meat, and frozen meat) stored in it during summer were measured at 10 min intervals for up to 3 h (12:00 PM to 15:00 PM). Trunk temperature steadily increased from 32.3 °C up to 41.5 °C, with longer exposure times. Food temperature also increased substantially during this period, reaching 33.5 °C (frozen meat), 35.3 °C (milk), 35.6 °C (tofu), 37.0 °C (egg), and 38.4 °C (fresh meat). Cloud cover and solar radiation affected car and food temperature, with lower cover and higher radiation associated with higher food temperatures (7.1 °C higher in the car trunk when compared to a situation of extensive cloud cover and low radiation, and 6.9 °C higher for eggs, 5.9 °C for milk, 5.0 °C for tofu, and 7.4 °C and 5.5 °C for fresh and frozen meat, respectively). The temperature of refrigerated foods (egg, milk, and fresh meat) reached 20 °C within 40 min (tofu: 60 min) and 30 °C within 90–110 min (tofu: 130 min). The temperature of frozen meat reached to danger zone (5–60 °C), which is associated with bacterial growth, after 90 min. Consumers should therefore realize the importance of time–temperature control, particularly in warm and sunny weather. Purchased foods should be transferred to a refrigerated environment as fast as possible, and the car trunk should be avoided. The present results can be used for consumer education, contributing to the recognition of the importance of food safety.     

Patulin accumulation in apples during postharvest: Effect of controlled atmosphere storage and fungicide treatments

The aim of this study was to assess the opportunities of Penicillium expansum to develop and produce patulin in apples under two different CA storage methods (LOW and U-LOW) at 1 °C. Differences in lesion diameter and patulin accumulation depending on CO₂ and O₂ partial pressure were studied. Further apple rot and patulin production during a three days post-storing stage at 20 °C was also monitored so that effect of further storage at room temperature could be assesed.Two lots of apples of Golden variety with different ripeness degrees were used. Half of each lot was fungicide treated. Apples were inoculated with patulin producer P. expansum strains and stored at 1 °C for either two month or 2.5 months at both LOW and U-LOW conditions. The extent of lesions and patulin accumulation both at the end of CA cold storage and after three days at 20 °C were assessed. CA storage conditions had strong significance in P. expansum growth on apples and factors such as fruit ripeness, fungicide treatment and time at the storage room had significant influence. In general, bigger lesions were observed under U-LOW than under LOW conditions, lesions being similar or bigger when increasing the storage time from 2 to 2.5 months. P. expansum grew faster in riper apples, although fungicide application was clearly more effective for ripe rather than for underripe apples. Although lesions were evident after both storage conditions, no patulin was detected. Increase of lesion when fruits were subsequently stored at 20 °C was evident in all cases and patulin was detected at this moment. No differences in patulin content were found at this stage between LOW and U-LOW stored apples.     

Quantification and variability of Escherichia coli and Staphylococcus aureus cross-contamination during serving and consumption of cooked thick porridge in Lungwena rural households, Malawi

The study investigated bacterial transfer to cooked thick porridge via ladles and hands during serving in 29 households in Lungwena, rural Malawi. Household stored water used for hand and ladle washing, was contaminated with Escherichia coli and Staphylococcus. aureus from hands of members of the household or from contaminated ladles used in food preparation. The results showed that hands became contaminated with E. coli and S. aureus cells in the range 0.6–3.7 and 2.2–4.3 log₁₀ CFU/cm², respectively, following washing with the contaminated water. Ladles became contaminated with 0.9–3.2 log₁₀ CFU/cm² of E. coli cells whereas contamination with S. aureus on ladles ranged between 1.9 and 4.6 log₁₀ CFU/cm². Bacterial transfer from hands to food ranged from <1 to 3.6 log₁₀ CFU/g for E. coli and 2.1 to 4.2 log₁₀ CFU/g for S. aureus. Ladle surfaces transferred from 1.3 to 3.1 and from 1.2 to 4.3 log₁₀ CFU/g of E. coli and S. aureus, respectively, on to the food. Contamination of food by hands was significantly (p < 0.05) higher than that of ladles and transfer of S. aureus was significantly (p < 0.05) higher than that of E. coli. The amount of bacteria transferred to the recipient depended on the wash water type and bacteria type. The study has demonstrated that although the traditional cooking of thick porridge inactivates S. aureus and E. coli, the porridge can be contaminated with bacteria during consumption using hands and serving on to a plate with wooden ladles.     

Changes in the concentration of aflatoxin M1 during manufacture and storage of White Pickled cheese

In this study White Pickled cheese was produced from cow’s milk contaminated artificially with aflatoxin M₁ (AFM1) at two different levels, 1.5 and 3.5 μg/kg (ppb), and the effects of process stages on the AFM1 contents were investigated. Pasteurization at 72 °C for 2 min caused losses of AFM1 about 12% and 9%, respectively, in milk contaminated with 1.5 μg/kg AFM1, and 3.5 μg/l AFM1. These losses were found to be statistically significant (P < 0.01). After the cheese production, about 56% and 59% of total AFM1 remained in cheese–curd while about 32% of total AFM1 transferred to the whey for both 1.5 μg/kg and 3.5 μg/kg AFM1 contaminated milk. After 3-month storage in brine, AFM1 content of cheeses produced from 1.5 and 3.5 μg/kg AFM1 contaminated milks decreased by 2.9% and 2.8%, respectively. Changes in AFM1 content of cheese samples were found statistically insignificant (P > 0.05 and P > 0.01) for 3-month storage periods.     

Time–temperature profiles of infant milk formula in hospitals and analysis of Enterobacter sakazakii growth

The purpose of this study was to assess the temperature conditions in neonatal care units for the preparation and storage of infant milk formula (IMF) and infant feeding using bottles and continuous feeding syringes. Enterobacter sakazakii in IMF for feeding infants has been chosen as the subject of this study because of the high risk incurred by IMF manufacture without total microbial destruction and the high sensitivity and mortality rates of this population group.From IMF preparation till neonate feeding, time–temperature profiles of IMF samples were monitored and analysed. In order to show the health impact of this data, potential E. sakazakii growth was calculated. As IMF can be also contaminated with Salmonella, potential Salmonella growth was also calculated. However potential E. sakazakii growth data were only analysed because of E. sakazakii and Salmonella spp. data being close.The study of 25 neonatal care units in 15 hospitals showed that the final potential growth for bottles depended on different parameters: initial water temperature, room temperature where IMF was prepared, cold storage temperature and time, reheating temperature and time. One parameter was not usually enough to determine the final growth increment alone and a well-controlled and high performance stage could result in an incorrect food safety indication if the other stages are less effective.On the other hand, the final potential growth for the continuous feeding syringes depended mainly on the feeding period since the IMF was kept in a particularly high ambient air temperature (≈25 °C) in the infant’s bedroom. This stage would be controlled first (with a cold syringe cover for example); then, as for bottles, the other stages would be controlled to result in a correct food safety indication.     

川西北地区海相烃源岩地球化学特征、分布规律及天然气勘探潜力

川西北地区为近年来四川盆地天然气勘探的热点地区,但时至今日对该区海相烃源岩的地球化学特征和分布仍缺乏全面的研究.选取8条露头剖面对川西北地区下震旦统陡山沱组、上震旦统灯三段、下寒武统筇竹寺组、下志留统龙马溪组、中泥盆统、中二叠统茅口组、上二叠统龙潭组/吴家坪组和大隆组8套海相烃源岩进行了系统的有机地球化学分析,探讨了该...     

N层同轴圆柱地层中电势Green函数的精确解

针对裸眼井附近地层为同轴圆柱多层结构,本文讨论了 N 层结构中稳定电流场电势的 Green 函数问题,并分别对点电流源位于井眼内和任一地层中的两种情形,求出了 Green 函数的精确解。这些解对于电阻率测井和自然电位测井工作是有用的。