Effect of Operating Parameters on the Spray Drying of Tomato Paste

The production of tomato powder from tomato paste using the spray drying technique has been investigated in this work. The influence of a number of process variables, namely, feed total solids, feed flow rate, feed temperature, air temperature, air flow rate, and starch addition on the physical properties of spray‐dried tomato powder was investigated. The product properties studied were total solids, average particle diameter, bulk density, and solubility. The increase in the feed total solids increased tomato powder total solids, particle size and bulk density and decreased its solubility, while the increase in the feed flow rate decreased tomato powder total solids and solubility, and increased the average particle size and bulk density.     

Biocontrol of Pests on Plant Crops in Denmark: Present Status and Future Potential

In this review, the status of biocontrol in plant crops in Denmark is analysed and factors governing the present use and future potential are described. In glasshouse vegetables, biocontrol is the dominant method to control pests while it is much less used in glasshouse ornamentals. On outdoor crops, the use of biocontrol is negligible. The main factors determining future prospects include: research, political initiatives, the scale of organic farming, the interest of companies marketing and advising on biocontrol, and public opinion. Good communication between scientists, advisers, growers, government authorities and the public has occurred for many years in Denmark, and has been essential for the successful implementation of biocontrol in glasshouses. Future development of microbial control (to which some organic growers and some members of the public show concerns) will require both research and a debate among the partners, particularly about environmental safety.     

Observers'' bias in the assessment of pest and disease symptoms in leek

In the vegetable crop leek, Allium porrum L., the performance of observers was compared to the real situation of pest and disease infestation. In two experiments the infestation of plants in a number of rows was meticulously investigated thus reflecting the real situation as contrasted with the results of one or more observers. Included were the symptoms of leek moth (Acrolepiopsis assectella Zeller) feeding, both fresh and old, of onion thrips (Thrips tabaci Lindeman) feeding and of infestation with rust (Puccinia allii Rud.). The method of scouting was similar to growers' practice in commercial leek growing. The results show that even trained scouts vary considerably in accuracy when assessing infestation in rows at the same field. A group of observers show individual patterns of estimation, a wide variation in ability to make a correct assessment and a strong density dependencey of deviations of the real situation with the perceived density of the symptoms in the crop.     

Heavy-metal accumulation in crops grown on sewage sludge amended with metal salts

Poplar (Populus euramericana Robusta), oats (Avena sativa L. Leander), maize (Zea mays L. Ona 36), English ryegrass (Lolium perenne L.), butter head lettuce (Lactuca sativa L. Reskia), spinach (Spinacia oleracea L. Subito) and French beans (Phaseolus vulgaris Prelude), were grown in pots with pure sewage sludge (pH 6.7), amended with Cd, Cr, Cu, Ni, Pb and Zn acetates, either added singly or in combination, to study metal effects on plant growth and metal uptake. Phytotoxic metal doses varied with metal and plant species, increasing in the order Cd<Ni<Cu<Zn<Cr and Pb. The threshold dose of toxic metals applied in combination was generally lower than that of metals given singly. Addition of Cd, Ni and Zn was clearly reflected in the respective plant concentrations. This was much less so for Cu, whereas Cr and Pb concentrations were not affected in most plant species. Critical plant (leaf) metal concentrations were lower for metals applied in combination than for single metals. Because of such phenomena the use of critical levels as a diagnostic tool for determining potential multiple metal toxicity is limited.     

Fiber optic monitoring of carbamate pesticides using porous glass with covalently bound chlorophenol red

An optical fiber biosensor for the determination of the pesticides propoxur (Baygon®) and carbaryl, two of the most commonly used carbamate insecticides in vegetable crops, is described. A pH indicator, chlorophenol red, is used as optical transducer of the inhibition of the enzyme acetylcholinesterase by the analytes. The biorecognition element is covalently immobilized onto controlled pore glass beads (CPG) and packed in a thermostatized bioreactor connected to a flow-through cell that contains CPG-immobilized chlorophenol red placed at the common end of a bifurcated fiber optic bundle. In the presence of a constant acetylcholine concentration, the colour of the pH sensitive layer changes and the measured reflectance signal can be related to the carbamate concentration in the sample solution. The performance of the biosensor has been optimized using a flow injection system. The linear dynamic range for the determination of carbaryl and propoxur spans from 0.8 to 3.0 mg l⁻¹ and from 0.03 to 0.50 mg l⁻¹, respectively. The detection limit (3 s) of the biosensor for propoxur (0.4 ng) is lower than that measured for carbaryl (25 ng). Reproducibility, stability and interference studies of the optical device are reported. The biosensor has been applied to the determination of propoxur in spiked vegetables (onion and lettuce) using ultrasound extraction, achieving recovery values between 93 and 95% for onion samples at the different concentration levels assayed.     

兰州八里镇蔬菜基地春季土壤纤毛虫群落特征

2005年4月至2007年6月,用活体观察和固定染色方法对兰州八里镇蔬菜基地春季土壤纤毛虫的群落特征进行了研究.共鉴定出土壤纤毛虫67种,其中包括2个未定名种和14个中国土壤纤毛虫新纪录种.在八里镇蔬菜基地的土壤中鉴定到纤毛虫34种,隶属于3纲、7目、17科、18属;下毛目、肾形目、前口目为其优势类群;吻吴氏虫(Woodruffia rostrata)、近亲游仆虫(Euplotes afflnls)、苔藓圆纤虫(Strongylidium muscorum)、鱼形瘦尾虫(Uroleptus piscis)、似膜袋虫(Cyclidium simulans)等为其优势种.在对照样点(兰山)中鉴定到纤毛虫49种,隶属于3纲、9目、23科、30属;下毛目、盾纤目、肾形目和篮口目为其优势类群;苔藓游仆虫(E.muscicola)、近缘殖口虫(Gonostomum affine)、皮速体虫(Tachysoma pellionella)、食藻斜管虫(Cyclidium simulans)等为其优势种.八里镇蔬菜基地和对照样点的Gleason-Margalef物种多样性指数分别为3.672、5.393;与对照样点土壤纤毛虫的群落Jaccard相似系数为0.239.结果表明,八里镇蔬荣基地春季土壤纤毛虫的物种多样性与对照样点相比有所降低,其群落结构简单化.     

Oxidative DNA damage in humans: comparison between high and low habitual fruit and vegetable consumption

We investigated whether men with a habitual high consumption of vegetables and fruit have a lower excretion of 8 oxo 7,8 dihydro 2 deoxyguanosine 8 oxodG, a urinary marker for oxidative DNA damage, than men with a low consumption of vegetables and fruit. Ten pairs of healthy non smoking males aged between 28 and 59 years, matched for age 10 years and body mass index 2 kg m 2 were selected from a dietary validation study. Habitual food intake was estimated with 12 monthly 24 h recalls. Men in the high vegetable and fruit group consumed an average of 224 g day 1 range 101-330 g day 1 more vegetables and fruit than men in the low vegetable and fruit group. Excretion of 8 oxodG was 95 pmol kg 1 day 1 95 CI-29, 219 higher in the high vegetable and fruit group than in the low vegetable and fruit group paired t test, P = 0.11 . Excretion of 8 oxodG was not correlated with intake of vitamins, energy, fat, nor with blood concentrations of antioxidant pro vitamins, but it was inversely correlated with age. The present findings do not suggest that humans with a habitual high fruit and vegetables consumption have less oxidative DNA damage as measured by 8 oxodG excretion than men with low consumption of fruit and vegetables.