Diomar Augusto de Quadros

Qualidade do tomate de mesa cultivado nos sistemas convencional e orgânico

The presence of organic products in the aisles of big supermarket chains indicates a market potential for these products. However, there is little technical and scientific information. Thus, the objective of this work was to determine the quality of tomatoes grown under conventional (CS) and organic (OS) systems, on sale in the metropolitan area of Curitiba, Brazil. Samples were evaluated in terms of mass, specific weight, ash, total solids, total soluble solids, total titratable acidity, total soluble solids/total titratable acidity ratio, pH, vitamin C, nitrates, nitrites, multiresidues. There were no significant differences between conventional and organic tomatoes, except in a 5 per cent difference in humidity, according to the Tukey test. Regarding the toxicological analyses, multiresidues and benzimidazole were not detected up to the limit of 0.04 mg.kg-1 and likewise carbendazim up to 0.1 mg.kg-1. Pesticide residues belonging to the dithiocarbamate chemical group were identified at levels of 0.01 mg.kg-1 in two samples of conventionally cultivated tomatoes. These levels are below the recommended upper limit for mancozebe fungicide (2.0 mg.kg-1 CS2).

Qualidade pós-colheita do tomate de mesa convencional e orgânico

The objective of this work was to evaluate the postharvest quality of fruits grown using different systems. Conventional (CS) tomatoes of the variety Raisa and Organic (OS), variety Santa Clara rustic, were stored at 23.5 ± 2 oC, RH 74% ± 5 and analyzed for mass, specific weight, ash, total solids, total soluble solids, total titrable acidity, total soluble solids/total titrable acidity ratio, pH, vitamin C, Salmonella spp., total coliforms, faecal coliforms, molds and yeasts, and sensory analysis (using Quantitative Descriptive Analyses - QDA). The time of storage was of 13 days for the conventional tomatoes and 14 days for the organic tomatoes. Weight loss (3,74%) was lower for the conventional tomatoes. Both fruits were similar in the physical, chemical, sensory and microbiological analysis in the different maturity stages

Classificação do tomate de mesa cultivado nos sistemas convencional e orgânico

The objective of this work was the classification of the tomato (Lycopersicon esculentum Mill.) cultivated in the organic and conventional cropping systems and commercialized in the Metropolitan Area of Curitiba. Six samples of conventionally grown tomatoes and three samples of organic tomatoes were evaluated. The fruits were classified in groups (oblong and round), subgroups (mature green, breaker, pink, red and mature red), and classes (giant, big, medium and small). According to the occurrence of serious damage and small defects on the fruits, they were classified in types, which can be extra, special or selected and commercial. The samples of conventional systems were classified as round and with than two locules, while of organic systems was classified as oblong and with two locules. Concerning the classes, the medium fruits predominated in the pink and red subgroups. All the samples were classified as out of standard or type due to the occurrence of defects.

Ocorrência do processo de fixação biológica de N2 atmosférico na fermentação de fécula de mandioca

The initial phase of natural fermentation of cassava starch presents vigorous fermentation within the first 24 h and is characterized by a high ration of carbon/nitrogen. Consequently, the necessary nitrogen to the formation of biomass would be originated from outside of the system because the available protein content from cassava starch is very low and depending on biological fixation of atmospheric N2. To verify that hypothesis two essays were conducted with the nitrogen balance in the starch granule suspension during the initial 120 h of the fermentation process. The essays were set at room temperature and at the controlled temperature of 28 °C. No increase in the nitrogen content was detected suggesting that no involvement of atmospheric N2. Results suggest that the origin of the nitrogen to the fermentation process is the cassava starch itself. The cassava starch in the flour form possesses high C/N ratio whereas in the aqueous suspension the C/N ratio is lowered propitiating vigorous fermentation.