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This project evaluated the potential for using ozone gas as post-harvest treatment for control of disease in stored potatoes. Ozone is a short-lived, highly reactive oxidizing agent with demonstrated potential to control disease-causing microorganisms. Preliminary trials showed that the atmospheric concentration of ozone obtained using commercial ozone generation equipment depended on the room size and reactive demands in the treatment area. Ozone applied to freshly harvested seed-grade potatoes up to 0-20 mg O3/kg/hr for 1, 7 or 21 days had little significant effect on the incidence or severity of a range of diseases or tuber colour, but did increase tuber weight loss in a dosage-dependant manner. Continuous ozone application (1.9 mg O3/kg/hr) accentuated weight loss by the stored crop. Application of ozone (10-20 mg O3/kg/hr) and Purogene® (Chlorine dioxide; 200 ppm) for 1 day at the mid-point of the winter storage period had no effect on disease levels, skin colour or weight loss measured at the end of storage. When tubers were inoculated with a range of pathogens (Fusarium sambucinum, F. solani., Phytophthora infestans, Helminthosporium solani), introduced at wound depths appropriate to each disease, disease levels typically increased, however ozone treatment (20 mg O3/kg/hr) did not reduce development of any of these diseases. In the absence of potential interference by the surrounding storage environment, pure cultures of Fusarium spp., P. infestans and sclerotia of Sclerotinia sclerotiorum were exposed to 45 mg O3/plate/hr for 1 or 2 days. The ozone treatments had no effect on sporulation of any of the pathogens and did not reduce mycelial growth of Fusarium spp. Mycelial growth of Phytophthora and sclerotial germination of Sclerotinia were suppressed for the duration of the ozone treatment period, however normal growth resumed when the cultures were placed in ozone-free conditions. Ozone treatments (up to 320 mg O3/kg/hr for 2 days) did not reduce the sprouting ability of seed potatoes, however ozone treatments (~20 mg O3/kg/hr for 1, 7 or 21 days) significantly reduced wound periderm thickness of treated potatoes. Treating seed potatoes with ozone (0 or 20 mg O3/kg/hr for 1 or 2 days) prior to planting typically did not affect plant stand or yield, however under cool, wet conditions, ozone-treated seed potatoes produced poorer stands and yields relative to the controls. Based on the results obtained for the range of treatments evaluated in this project, ozone appears to have limited potential as a disease management tool in stored potatoes.

This project evaluated the potential for using ozone gas as post-harvest treatment for control of disease in stored potatoes. Ozone is a short-lived, highly reactive oxidizing agent with demonstrated potential to control disease-causing microorganisms. Preliminary trials showed that the atmospheric concentration of ozone obtained using commercial ozone generation equipment depended on the room size and reactive demands in the treatment area. Ozone applied to freshly harvested seed-grade potatoes up to 0-20 mg O3/kg/hr for 1, 7 or 21 days had little significant effect on the incidence or severity of a range of diseases or tuber colour, but did increase tuber weight loss in a dosage-dependant manner. Continuous ozone application (1.9 mg O3/kg/hr) accentuated weight loss by the stored crop. Application of ozone (10-20 mg O3/kg/hr) and Purogene® (Chlorine dioxide; 200 ppm) for 1 day at the mid-point of the winter storage period had no effect on disease levels, skin colour or weight loss measured at the end of storage. When tubers were inoculated with a range of pathogens (Fusarium sambucinum, F. solani., Phytophthora infestans, Helminthosporium solani), introduced at wound depths appropriate to each disease, disease levels typically increased, however ozone treatment (20 mg O3/kg/hr) did not reduce development of any of these diseases. In the absence of potential interference by the surrounding storage environment, pure cultures of Fusarium spp., P. infestans and sclerotia of Sclerotinia sclerotiorum were exposed to 45 mg O3/plate/hr for 1 or 2 days. The ozone treatments had no effect on sporulation of any of the pathogens and did not reduce mycelial growth of Fusarium spp. Mycelial growth of Phytophthora and sclerotial germination of Sclerotinia were suppressed for the duration of the ozone treatment period, however normal growth resumed when the cultures were placed in ozone-free conditions. Ozone treatments (up to 320 mg O3/kg/hr for 2 days) did not reduce the sprouting ability of seed potatoes, however ozone treatments (~20 mg O3/kg/hr for 1, 7 or 21 days) significantly reduced wound periderm thickness of treated potatoes. Treating seed potatoes with ozone (0 or 20 mg O3/kg/hr for 1 or 2 days) prior to planting typically did not affect plant stand or yield, however under cool, wet conditions, ozone-treated seed potatoes produced poorer stands and yields relative to the controls. Based on the results obtained for the range of treatments evaluated in this project, ozone appears to have limited potential as a disease management tool in stored potatoes.

This study focuses on investigating the effect of post-harvest handling conditions and storage time on the dehulling efficiency and cooking quality of two varieties of red lentils, as well as optimizing the dehulling conditions. The effects of storage time, storage moisture content and storage temperature, as well as the effect of different storage pre-treatments aiming to simulate post-harvest handling, were studied. Dehulling efficiency was mostly affected by the pre-milling moisture content, regardless of the storage conditions. Pre-treatments involving moisture content changes lowered the dehulling efficiency of both varieties of red lentils, whereas freezing and thawing cycles had less of a negative effect on the dehulling characteristics. Textural parameters were mostly affected by storage time; samples became harder after storage. The final recommendation arising from this study is to monitor the moisture content of lentils during storage as it has a detrimental effect on both the dehulling and cooking quality.

This study focuses on investigating the effect of post-harvest handling conditions and storage time on the dehulling efficiency and cooking quality of two varieties of red lentils, as well as optimizing the dehulling conditions. The effects of storage time, storage moisture content and storage temperature, as well as the effect of different storage pre-treatments aiming to simulate post-harvest handling, were studied. Dehulling efficiency was mostly affected by the pre-milling moisture content, regardless of the storage conditions. Pre-treatments involving moisture content changes lowered the dehulling efficiency of both varieties of red lentils, whereas freezing and thawing cycles had less of a negative effect on the dehulling characteristics. Textural parameters were mostly affected by storage time; samples became harder after storage. The final recommendation arising from this study is to monitor the moisture content of lentils during storage as it has a detrimental effect on both the dehulling and cooking quality.

Made available in DSpace on 2014-06-11T19:32:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-07-25Bitstream added on 2014-06-13T19:03:04Z : No. of bitstreams: 1 campos_co_dr_botfca.pdf: 2580813 bytes, checksum: 0454472d6d9a8e04547aab81ac54ae85 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho foi conduzido em quatro etapas, visando acompanhar o desenvolvimento das características físico-químicas de frutos de umbuzeiro (Spondias tuberosa Arruda); estabelecer a curva de crescimento do fruto e aspectos pós-colheita dos frutos do umbuzeiro, objetivando estabelecer estratégias para melhor conservar os frutos, tendo em vista que o fruto desta fruteira, caracteriza-se como uma fruta exótica, já alcançando o mercado europeu. As plantas escolhidas, localizam-se na quadrícula 400 e 420 de Longitude (W. C) e 80 e 100 de Latitude Sul, sendo colhidos frutos de vinte plantas em cinco Unidades Geoambientais. O delineamento experimental utilizado foi o inteiramente casualizado e o arranjo, a depender da situação, fatorial aninhado (nested). Concluiu-se neste trabalho que os umbuzeiros presentes nas Unidades Geoambientais da Depressão Sertaneja, apresentam grande variabilidade fenotípica, manifestada pelo peso médio do fruto, peso médio da polpa, teor de vitamina C e acidez titulável. De acordo com a curva de crescimento do fruto, os estádios podem ser visualizados pelo peso do fruto e pela coloração da casca. O florescimento do umbuzeiro ocorre entre setembro e outubro, a fecundação das flores não ocorre todas de uma só vez, são fecundadas paulatinamente no decorrer de trinta dias, em média, fazendo com que a colheita se estenda entre vinte e trinta e cinco dias. A classificação proposta, dos estádios de desenvolvimento foi de 1FTV-F (fruto totalmente verde. Figa - caroço esbranquiçado, em formação), 2FTV-D (fruto totalmente verde. Devéz - caroço duro, ponto de umbuzeitona), 3FTV-In (fruto totalmente verde. Inchado - início da pigmentação), 4FPA-M-1 (fruto com predominância do amarelo - Maduro 1), 5FTA-M-2 (fruto totalmente amarelo - Maduro 2), 6FTA-P (fruto totalmente amarelo - Passado). O conteúdo de vitamina C no suco... / This work was carried out in four stages in order to follow the development of the physical and chemical characteristics of umbu tree fruits (Spondias tuberosa Arruda) and to establish the fruit growth curve and aspects of postharvest of umbu tree fruits with the goal to establish strategies to improve conservation of umbu fruits since it is an exotic fruit reaching the European markets. The fruits were harvested from twenty plants randomly chosen in five Geoambiental unities located in quadrants 400 and 420 of longitude (W. C) and 80 and 100 of south latitude. The experimental design was completely randomized in a factorial (nested) arrangement when necessary. The conclusion was that the umbu trees present in the Geoambiental unities showed high variability expressed by average of fruit weight, fruit pulp, vitamin C contents and titrable acidity. According to the fruit growth curve the stage can be observed by fruit weight and coloration of rind. The bloom of umbu tree occurs between September and October, the fecundation of flowers do not develop at one time but instead gradually on average of thirty days and harvest occur between twenty and thirty five days. The proposal classification of umbu trees stages was the following: 1FTV-F (fruit totally green. Figa - seed white in formation), 2FTV-D (fruit totally green Devez - hard seed, ponto de umbuzeitona), 3 FTV -In (fruit totally green. Swelled - start of pigmentation, 4FPA - M - 1 (fruit predominantly yellow - ripe 1), 5 FTA -M - 2 (fruit totally yellow - ripe 2), 6FTA - P (fruit totally yellow - over-ripe). The vitamin C contents in umbu juice varied from 41, 9g in 100 ml in stage 1FTV - F (figa) to 8,5g in 100 ml in stage 5 FTA-M-2 (ripe 2). The titrable acidity, quantity of citric acid, varied from 4,5g in 100g of juice in stage 1FTV-F (figa) to 1,4g in 100g of juice in stage 5 FTA-M-2 (ripe 2). The soluble solids given... (Complete abstract click electronic access below)

This dissertation consists of three different essays evaluating solutions to postharvest challenges faced by farmers in Kenya and Tanzania. In the first essay we see that demand for a new storage technology the Purdue Improved Crop Storage (PICS) bags in Western Kenya, a completely new technology for almost the entire sample, was highly elastic and that a small proportion of the population would buy at the current market price. In the second essay we find evidence that farmers, who are primarily growing for maize consumption are more concerned about food safety in maize than traders, who are willing to pay less to keep the maize safer. In the third essay in Tanzania, we find that liquidity concerns at harvest prevent farmers from optimizing maize storage and sales decisions.

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