Thesis (M. Environmental Science))--North-West University, Potchefstroom Campus, 2007.

Cruciferous crops comprise one of the major crop divisions and contribute significantly to global crop production. Insect pests associated with cruciferous crops have the potential to destroy harvests. The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) and cabbage aphids, Brevicoryne brassicae (L.) and Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae) are considered the most important cabbage pests in South Africa. Pest control in cabbage is still heavily reliant on use of insecticides even though insecticide application usually result in increased pest status of P. xylostella. Use of integrated pest management (IPM) strategies may yet prove invaluable as a means of suppressing the more serious cabbage pests. Global interest in cultural control strategies, that includes intercropping of unrelated crop plants, has been rekindled because of problems experienced with pesticide use. A study that involved the planting of two field trials with cabbage and carrot plants in different ratios, as a substitutive intercropping system, was undertaken during the 2002/03 and 2003/04 planting seasons. Field trials had five treatments viz. control (cabbage monoculture sprayed with mercaptothion), cabbage monoculture (without chemical application), 1:1 intercropping (cabbage:carrots), 1:3 intercropping and 1:5 intercropping, replicated six times in a randomized block design. Insects were sampled weekly by removing the third-youngest open leaf, from one plant per plot (six plants per treatment). Feeding damage to cabbage leaves was assessed visually by rating 14 plants per plot according to a numeric scale based on damage severity. P. xylostella and aphid parasitism levels were determined. Prominence values were calculated for P. xylostella larvae and aphids for each treatment per sampling date. P. xylostella infestations and parasitism levels were significantly (P ≤ 0.05) lower in control treatments. Intercropping ratio did not have a significant impact on pest infestations. P. xylostella infestations and parasitism on intercropping treatments did not differ significantly (P > 0.05) from that on monoculture plots (except for 1:5 intercropping during the 2003/04 season). Cotesia plutellae (Hymenoptera: Braconidae) was the dominant parasitoid and parasitism levels were significantly correlated with P. xylostella infestation levels. Prominence values showed a decline in P. xylostella infestations on intercropping treatments towards the last sampling date during both seasons. Feeding damage severity was lowest on the control treatment but similar for other treatments for both seasons. Aphid infestations were significantly (P ≤ 0.05) lower on the control treatment, but did not differ significantly between intercropping treatments. Aphid prominence values indicated possible suppression of infestations at low population levels during the early part of the season. Aphid parasitism was low during both seasons. It seems more likely that the reduction in insect infestation levels reported from the literature are related more to spatial arrangement of plants than cropping ratios. The observed suppression of aphid infestation levels on intercropped plots early in the season may be valuable in reducing the need for early chemical applications. The limiting of early insecticide application against aphids may result in a reduced pest status of P. xylostella, due to the conservation of C. plutellae populations. / Thesis (M. Environmental Science))--North-West University, Potchefstroom Campus, 2007.

Cruciferous crops comprise one of the major crop divisions and contribute significantly to global crop production. Insect pests associated with cruciferous crops have the potential to destroy harvests. The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) and cabbage aphids, Brevicoryne brassicae (L.) and Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae) are considered the most important cabbage pests in South Africa. Pest control in cabbage is still heavily reliant on use of insecticides even though insecticide application usually result in increased pest status of P. xylostella. Use of integrated pest management (IPM) strategies may yet prove invaluable as a means of suppressing the more serious cabbage pests. Global interest in cultural control strategies, that includes intercropping of unrelated crop plants, has been rekindled because of problems experienced with pesticide use. A study that involved the planting of two field trials with cabbage and carrot plants in different ratios, as a substitutive intercropping system, was undertaken during the 2002/03 and 2003/04 planting seasons. Field trials had five treatments viz. control (cabbage monoculture sprayed with mercaptothion), cabbage monoculture (without chemical application), 1:1 intercropping (cabbage:carrots), 1:3 intercropping and 1:5 intercropping, replicated six times in a randomized block design. Insects were sampled weekly by removing the third-youngest open leaf, from one plant per plot (six plants per treatment). Feeding damage to cabbage leaves was assessed visually by rating 14 plants per plot according to a numeric scale based on damage severity. P. xylostella and aphid parasitism levels were determined. Prominence values were calculated for P. xylostella larvae and aphids for each treatment per sampling date. P. xylostella infestations and parasitism levels were significantly (P ≤ 0.05) lower in control treatments. Intercropping ratio did not have a significant impact on pest infestations. P. xylostella infestations and parasitism on intercropping treatments did not differ significantly (P > 0.05) from that on monoculture plots (except for 1:5 intercropping during the 2003/04 season). Cotesia plutellae (Hymenoptera: Braconidae) was the dominant parasitoid and parasitism levels were significantly correlated with P. xylostella infestation levels. Prominence values showed a decline in P. xylostella infestations on intercropping treatments towards the last sampling date during both seasons. Feeding damage severity was lowest on the control treatment but similar for other treatments for both seasons. Aphid infestations were significantly (P ≤ 0.05) lower on the control treatment, but did not differ significantly between intercropping treatments. Aphid prominence values indicated possible suppression of infestations at low population levels during the early part of the season. Aphid parasitism was low during both seasons. It seems more likely that the reduction in insect infestation levels reported from the literature are related more to spatial arrangement of plants than cropping ratios. The observed suppression of aphid infestation levels on intercropped plots early in the season may be valuable in reducing the need for early chemical applications. The limiting of early insecticide application against aphids may result in a reduced pest status of P. xylostella, due to the conservation of C. plutellae populations. / Thesis (M. Environmental Science))--North-West University, Potchefstroom Campus, 2007.

Thesis (M.Sc.)--Memorial University of Newfoundland, 1997. / Bibliography: leaves 74-83.

Orientador: Osvaldir Pereira Taranto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-22T21:38:15Z (GMT). No. of bitstreams: 1 Andreola_Kaciane_M.pdf: 3188317 bytes, checksum: 937f50d9c69fbd22b5433bec186c084b (MD5) Previous issue date: 2013 / Resumo: A cenoura está entre as hortaliças com maior cultivo no cenário nacional consumida tanto na forma in natura quanto processada. Esta hortaliça apresenta elevado valor nutritivo e destaca-se pelo alto teor de ?-caroteno. Contudo, como a cenoura in natura é um produto perecível este vegetal tem sido utilizado na forma desidratada como ingrediente para a formulação de produtos industrializados. A secagem é uma operação unitária que possibilita maior vida de prateleira, além de redução dos custos com armazenamento e transporte. Um método alternativo para a secagem de alimentos é a secagem com aplicação de micro-ondas, pois o calor é gerado no interior do material diferente da secagem convencional com ar quente, o que resulta em menor tempo de processamento. Este trabalho teve como objetivo o estudo da secagem convectiva de cenoura combinada com aplicação de micro-ondas em secador de leito fixo. Para tanto, técnicas de planejamento experimental e análise estatística dos resultados foram empregadas para avaliar a influência da temperatura do ar de secagem e da potência de micro-ondas na qualidade do produto em termos de umidade final, cor, textura e encolhimento. Foram efetuados dois planejamentos experimentais, sendo que no Planejamento A, a energia de micro-ondas foi aplicada durante todo o processo de secagem, enquanto que para o Planejamento B, a radiação foi aplicada após 30 minutos iniciais de secagem convectiva a 80 °C. Além disso, foi realizada a secagem de cenoura somente por convecção a 70 e 80 °C. A cinética de secagem apresentou um período de taxa constante, seguido de um período de taxa decrescente, tanto para a secagem com aplicação de micro-ondas quanto para a secagem puramente convectiva. A secagem com aplicação contínua de micro-ondas acelerou a retirada da umidade em relação à secagem convectiva, reduzindo o tempo de processo em pelo menos 60%. Já para o Planejamento B, em que a radiação foi aplicada a partir dos 30 minutos iniciais de secagem, o tempo de processo foi reduzido em pelo menos 50% comparado ao processo convectivo. O Planejamento A resultou em menor tempo de processo e maiores taxas de secagem em relação ao Planejamento B, sendo que em ambos foram obtidos valores para o conteúdo final de umidade, na faixa de 7,18 a 14,57% (b.u.). O aumento da potência de micro-ondas proporcionou menor encolhimento e umidade final, porém foi observada maior degradação da cor e textura mais dura, para ambos os planejamentos. A temperatura do ar, por sua vez, apresentou uma influência secundária na secagem quando micro-ondas foram incorporadas ao processo. As melhores condições de secagem obtidas para o Planejamento A, de acordo com a análise das curvas de nível e função desejabilidade global foram: temperatura do ar de 50 °C e potência de micro-ondas de 100 W. O segundo planejamento diferiu apenas quanto à temperatura do ar, apresentando como melhores condições de secagem: temperatura do ar de 45 °C e potência de micro-ondas de 100 W, mantendo-se a secagem inicial convectiva a 80 °C durante 30 minutos / Abstract: Carrot is among the most cultivated vegetables on the national scenery, being consumed fresh or in the processed form. This vegetable presents a high nutritional value and is distinguished by its high content of ?-carotene. However, since carrot is a perishable product, it has been used in dried form, as an ingredient in the formulation of industrial products. Drying is a unit operation which allows longer shelf-life and reduces storage and transportation costs. Microwave drying represents an alternative method for food drying, once that the heat is generated inside the material differing from conventional drying by hot air, which results in shorter processing time. The aim of this work was to investigate microwave assisted convective air drying of carrots in a fixed bed dryer. Therefore, experimental design techniques and statistical analysis of the results were performed to analyze the influence of the air temperature and microwave power level on the product quality in terms of final moisture content, color, texture and shrinkage. Two experimental designs were performed which in the experimental design A, microwave power was applied during the whole drying process, while in the experimental design B, radiation was applied after 30 minutes of convective drying with air temperature at 80 °C. Moreover, it was also performed the drying of carrot only by convective drying with air at 70 and 80 °C. Drying kinetics showed a constant drying rate period, followed by decreasing drying rate period for both microwave and convective drying. Microwave continuous drying accelerated the removal of moisture content compared to convective drying, reducing at least 60% of the process time. In which the application of radiation was carried out after 30 minutes of drying, the process time was reduced by at least 50% compared to the convective drying. The experimental design A resulted in shorter process time and higher drying rates in relation to experimental design B, once that both were obtained values for the final moisture content in the range from 7.18 to 14.57% (w.b.). The increase on microwave power level provided less shrinkage and final moisture, however greater color degradation and harder texture were observed for both experimental designs. On the other hand, the air temperature showed a secondary effect on the drying process when the microwaves were incorporated into the process. The best conditions obtained for experimental design A, according to the analysis of contour curves and global desirability function were: air temperature at 50 °C and microwave power level of 100 W. The second experimental design differed only in the air temperature, presenting the best drying conditions: air temperature at 45 °C and microwave power level of 100 W, maintaining initial convective drying at 80 °C for 30 minutes / Mestrado / Engenharia de Processos / Mestra em Engenharia Química

Genetically enhanced high-carotene Beta III hybrid carrot was compared to a commercial carrot cultivar, Nantes Careless, for carotene content and macronutrient composition. Beta III contained more than twice the total carotene content of Nantes Careless, with α-carotene/β-carotene ratios higher in Beta III. Total solids from protein, lipids, and carbohydrate were greater in Beta III than in Nantes Careless. Beta III contained about five times the amount of sucrose and one-fifth the amount of glucose and fructose than Nantes Careless or reported literature values. Comparison of the bioavailability of carotenes in Beta III and Nantes Careless to purified β-carotene and retinyl acetate standards was made using two bioassays: the liver storage, slope-ratio assay and a curative growth study. Beta III provided liver retinol stores equivalent to stores provided by Nantes Careless, β-carotene, and retinyl acetate at dosage 300 RE. At 600 RE, only retinyl acetate increased liver retinol storage with dose. Carotene sources did not increase liver retinol storage, presumably owing to the mechanisms that prevent carotene vitamin A toxicity. Growth study results indicated vitamin A potency of Beta III was not equivalent to that provided by retinyl acetate. Slopes of the growth response curves for Nantes Careless and β-carotene were not significantly different from retinyl acetate; the slope of the Beta III growth response curve was significantly different. All carotene sources were similar to retinyl acetate in the curvilinear response of the growth curves. The appropriate fit of the quadratic function to the growth response curves suggested 12 RE/d was greater than requirement. The differences in results of the two bioassays used to determine bioavailability of carotenes in Beta III may be explained by a number of factors. The utilization of β-carotene from Beta III may be affected by a-carotene or other carrot constituents for absorption or conversion to vitamin A, or both. Stored liver retinol may be a combination of retinol and a-retinol with reduced vitamin A activity. The growth assay may be more sensitive to external variables that cannot be controlled.

No description available.

The carrot weevil, Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae), is an insect pest in carrot production in Ontario. The aim of this study was to survey the egg parasitoids attacking the carrot weevil in carrot fields in Ontario, and elucidate the seasonal and chemical ecology of these natural enemies. / Field surveys were conducted during three years in commercial carrot fields in the Holland Marsh and district marshes to detect the presence of carrot weevil egg parasitoids, to determine their geographical distribution and to evaluate the effect of insecticides on the rate of emergence and the activity of parasitoid adults. Two egg parasitoids, Anaphes listronoti Huber and A. victus Huber were found. The dominant species Anaphes listronoti is gregarious, was recovered from most of the sampled fields and was distributed in all sampled marshes whereas the solitary parasitoid A. victus was only sporadically found in the Holland Marsh. These Anaphes species occurred in carrot fields from the end of April to the beginning of September and seasonal parasitism averaged 33% in commercial carrot fields and up to 79% in an untreated plot. The insecticides phosmet, diazinon and cypermethrin used in carrot production, did not affect emergence rate of parasitoid adults indicating that immature stages are protected against insecticide penetration in the host egg. However, insecticide applications decreased parasitism rates and suggest a lethal effect on parasitoid adults by direct contact and insecticide residues, although no difference was observed between treatments. / Laboratory studies were performed to determine the existence of a sexual pheromone produced by female A. listronoti using a four-arm olfactometer. An automated system of insect tracking was developed to quantify male behavior in the olfactometer. The response of males to odor emitted by virgin females less than two days of age was measured. Virgin females less than one-day-old released a long-range pheromone from 4 hours until 16 hours after the onset of the photophase. Females of one and two days of age started to emit the sexual pheromone earlier than younger females.

Carotenoids are essential for visual function, however their potential role in Computer Vision Syndrome (CVS) is not known. By providing carrot powder, this study examined carotenoid metabolism and visual function in CVS. CVS participants were recruited into a double-blind, placebo-controlled, repeated measures trial (n=19, ages 20-65) and were randomized to 2 supplementation groups; control (15g cream of wheat powder) or carrot enriched (15g carrot powder, 33% of vitamin A RDA for adults) in an isocaloric pudding and yogurt for 4 weeks. Retinal function, self-perceived vision status, and plasma carotenoids/retinoids were assessed, along with plasma lipids and oxidative stress markers. Photopic b-waves marginally improved following supplementation reflecting higher phototransduction, possibly due to increased plasma carotenoid/retinoid levels. LDL cholesterol and oxidative stress markers showed trending reductions illustrating a protective role of the carrot. Carrot powder, at a minimal supplementation dose, can be recommended for CVS.

Orientador : Fernanda Elizabeth Xidieh Murr / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T14:22:41Z (GMT). No. of bitstreams: 1 ArevaloPinedo_Aroldo_D.pdf: 8941567 bytes, checksum: 91ffc09e41728c02c23f58f3f126d55e (MD5) Previous issue date: 2003 / Resumo: Neste trabalho estudou-se experimentalmente a cinética de secagem a vácuo de cenoura e abóbora "in natura" e pré-tratadas por congelamento e branqueamento. As corridas experimentais foram conduzidas em um secador a vácuo, nas pressões de 5, 15 e 25 kPa e temperaturas de 50, 60 e 70°C. Estudou-se a influência da pressão e temperatura, assim como os pré-tratamentos adotados, sobre a cinética de secagem. A análise do efeito dos pré-tratamentos e dos parâmetros pressão e temperatura sobre a velocidade de secagem, revelou que os melhores valores foram obtidos com a temperatura de 70°C e pressão de 5 kPa para as amostras pré-tratadas por congelamento. Quanto ao tipo de matéria-prima utilizado a abóbora apresentou maiores velocidades de secagem que as de cenoura independente do tratamento recebido e da condição de secagem utilizada. As curvas experimentais de secagem foram ajustadas ao modelo difusional de Fick para uma placa plana infinita considerando ou não o encolhimento. Os valores da difusividade efetiva considerando o encolhimento da amostra são menores que os calculados sem considerar este fenômeno / Abstract: In this work it was studied experimentally the kinetics of carrot and pumpkin under vacuum drying in nature and pre-treatment by freezing and bleaching. The experimental runs were driven in a dryer under vacuum, at pressures of 5, 15 and 25 kPa and temperatures of 50,60 and 70oe. The influences on the drying kinetics of the pressures and temperature were studied, as well as effect of adopting pre-treatment. It was observed that the best values were obtained at the temperature of 70oe and pressure of 5 kPa for the samples pretreatment by freezing. As concerns to the raw material employed pumpkin presented higher drying speeds than the one shown by carrot, independently of the treatment received and of the operational condition of drying. The experimental curves of drying were adjusted to the difusional model of Fick for an infinite slab with or without shrinkage. The values of effective diffusivity obtained by considering the samples shrinkage were smaller than those calculated without considering this phenomenon / Doutorado / Doutor em Engenharia de Alimentos