Caracterização química de tomates (Lycopersicon esculentum Mill.) empregando análise por ativação neutrônica instrumental / Chemical characterization of tomatoes (Lycopersicon esculentum Mill.) by using instrumental neutron activation analysis

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The tomato is the second most cultivated vegetable after the potato, having an effective participation in the human diet. Its food value remains paradoxical. At same time it is recognized as a functional food with nutraceutical properties, the tomato receives criticism due to the way it is usually cultivated, i.e. under heavy amounts of synthetic fertilizers and pesticides. There are many causes of variation that may change the fruit composition. In this aspect, the current work aimed at collecting samples in a universe that comprises different factors, including cultivars for fresh market and for processing, conventional and organic cultivation systems, geographical regions and soil types. The main objective of this work was the chemical element characterization of tomato in view of the identification of elements of agronomical and nutritional interest and establishing concentration ranges for the fruits produced under different sources of variation. The specific objectives comprehended studies of sample representativeness and studies of the influence of ripening stages and soil on the chemical composition of tomato fruits. Tomatoes from the cultivars AP 533, Colibri and T-92 were sampled in farms located in cities of São Paulo State. The determination of the chemical elements was carried out by using the primary method of measurement instrumental neutron activation analysis (INAA). The quality of the analytical procedure was evaluated by means of accuracy and reproducibility of reference materials results. The study of sample representativeness showed that the required number of 12 samples to represent the tomato in the field, considering 15% as the maximum deviation allowed by the analyst. The within-sample variability was evaluated by means of 12 analytical portions taken from one sample. The results demonstrated the homogeneity of the material. The chemical elements Br, Ca, Co, Cs, Fe, K, La, Na, Rb, Sr and Zn were determined in the samples of pulp, seeds and soils. The analysis of fruits at mature green and pink stage indicated higher concentrations of Ca, Fe, K, Na, Rb and Sr in the tomatoes at pink stage, while Br, Co, Cs and Zn did not show any significant difference (p <0.05). The soils from the six studied farms presented different chemical compositions. However, no correlations were observed between the chemical element concentrations found in the samples of pulp and soil. The results of chemical characterization of tomatoes allowed making important inferences with relation to the chemical elements behavior. K and Ca were the most abundant nutrients in the pulp and seeds. Br, Co, Cs, Rb and Sr concentrations in the pulp showed significant differences (p <0.05) for both cultivation systems and cultivars. Fe, K, Na and Zn concentrations in the pulp were not affected by the cultivation systems, being the differences found intrinsic to each cultivar. The pulp and seeds from the tomatoes of the three cultivars did not present any significant difference for Ca. Br allowed the discrimination of organic and conventional tomatoes, the later showing the higher concentrations. Multivariate analysis of the pulp results revealed a trend in clustering by categories, both in terms of cultivars and cultivation system, although the later showed less clear results. On the other hand, the seeds presented higher trend in clustering by the cultivar factor

ASSUNTO(S)

cultivars sistemas de produção tomatoes inaa cultivares química analítica productions systems analytical chemistry tomate food alimento inaa

ACESSO AO ARTIGO

Documentos Relacionados