Avaliação do perfil mineral da alface crespa (Lactuca sativa L.) produzida em diferentes sistemas de cultivo utilizando o método de espectometria de fluorescência de raios – X (EDX).

Abstract

In recent decades, Brazil watched a large increment on farm machinery that placed the country as the world largest producer and consumer of pesticides. The use of chemicals in growing vegetables is being researched due to reports witch shows that it´s use modifies the soil elements concentration, affecting the chemical composition of cultivars, possibly becoming a vehicle for people chemical contamination through food. On this, the aim of this study was to analyze the mineral profile of curly lettuce (Lactuca sativa L.), produced in different cropping systems, by X-ray fluorescence spectrometry method (EDX). For this, the lettuce grown in traditional soil were collected at Lagoa Seca-PB rural zone; hydroponic and semi organic samples were collected New Forest Town-PB, in both cases questionnaires were applied to producers. Tha organic samples were grown and collected at Cuité-PB Federal University Campus. All samples were collected in their final stage of maturity, after this, they were washed, selected, submitted to controlled stove drying, grinded, packaged and sent to the analysis. The soil samples were collected immediately after harvesting lettuces, at a depth of approximately 20 cm in three different points of the beds, being subsequently homogenized, subjected to controlled stove drying, grinded, packaged and then analyzed. The results were evaluated by variance analysis (ANOVA), and calculation system used was Sigma Stat 3.1 program. The mineral profile analysis identified 14 minerals in the curly lettuce samples, but only 8 of them expressed significant results (p<0,05) in terms of concentration, considering the different cropping systems. Potassium was the element that had the highest content of all samples of lettuce; moreover, the correlation between the use of chemicals witch are souses of minerals, their concentration in the soil and in the lettuces was observed only in part of analyzed elements. The results were written in percentages, and when converted to milligrams, considering the standards for lettuce, have shown higher values than those found in some references used. About the questions made to producers of vegetables at the time of harvesting, demonstrated that despite the existence of leaflets containing information about the use of chemicals, they aren´t always followed. Finally, it´s concluded that the qualitative profile of minerals evaluated by EDX was similar to that observed in other studies, being this method, however, able to identify a greater variation of mineral than that shown by others. The quantitative data, in turn, require more studies and a standard method for food. Even though there wasn´t no major differences between the cropping systems analyzed on their mineral profile, both qualitative and quantitative, the shorter use of chemicals associated with the use of resources that can ensure the soil control and quality, is still considered the best and safer method of producing food.