Secagem, armazenamento e qualidade de folhas de Cymbopogon citratus (D.C.) Stapf / Drying, storage and quality of Cymbopogon citratus (D.C.) Stapf leaves

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The marketing of the medicinal plants is among a very competitive market. In Brazil, in spite of the effective legislation, the plant medicine it is still marketed under uncertain way due to the inefficiency in quality control mainly in the post harvest stage of the plants which serve as the raw materials for the medicines. The Cymbopogon citratus (D.C.) Stapf species is well known e used in several countries for medicinal purposes and also it has being used and applied in the pharmaceutical, food, cosmetic and perfumery industries. Because of its importance, several works have being done related to this species. Although the post harvesting process steps such as drying and storage are lack of informations about them. Therefore due to the growing market of such species as medicinal plant, this work was conducted in order to get more specific knowledges about it in the area of pre processing engineering for analyzing and solving problems of drying the C. citratus leaves allowing to predict the quality changes and have the response to different packing ways during the storage. It also was evaluated the quality of the different brands and packing type of the tea species marketed in the local stores or free market square. The experimental procedure was divided in three steps: drying, storage and evaluation of differents C. citratus tea marks. In the drying, the C. citratus leaves were cut with different lengths (2, 5, 20 and 30 cm) and dried by the use of an laboratory model drier using propane gas for air heating. The leaves were dried at different drying air temperatures (30, 40, 50 and 60C). The drying experimental data were adjusted to different empiric and semi-empiric equations for modeling the drying curves. In the dried leaves storage, were evaluated in term of their color and their essential oil chemical composition. Three different packing methods were used for storing the dried leaves. The first one in polypropylene bag inside of two Kraft paper bags, the second one in polypropylene bags and the third one in two Kraft paper bags inside of polypropylene bag. Every two months the leaves were taken out for evaluating them for their color, moisture content, essential oil content and chemical composition of the essential oil. For evaluating the quality of the commercial dried leaves it was used the colorimetric analysis for color evaluation, essential oil yield and, also the identity and their constituent quantities. According to the results it can be concluded that: a) the Modified Page mathematical model was that best represented the drying experimental data; b) The diffusion coefficient presenting results within 1.00 x 10-11 to 6.03 x 10-11m2 s-1; c) the activation energy varied from 35.78 to 51.19 kJ mol-1; d) shorter leaves cut resulted on higher essential oil yield in relation to the longer leaves cut; e) the drying temperature of 50C showed be better for drying the species resulting; f) during the storage, the essential oil content of the dried leaves decreased linearly, independent to the type of wrapping but still within the limits of what the Brazilian legislation establishes for pharmaceutical products; g) the citral and mirceno contents were reduced in function of their storage period, the amount of citral in the product after 12 months maintained within the Brazilians Phamacopeia IV advocates for the species in question; h) in the relation to the product color during the storage, there was larger alteration in the polypropylene wrapping, which didnt protect the product of the ambient light, resulting, at the end of 12 months, in a product with a more grayish green color; i) within the evaluated tea brands, 54.5% of them presented essential oil content within the Brazilian legislation specifications; j) the dried leaves grinding process resulted in less essential oil content; l) the concentrations of citral, mirceno and geraniol showed the existing of a great variability on chemical composition of the essential oil obtained from different brands.

ASSUNTO(S)

armazenamento post-harvesting secagem drying medicinal plants cymbopogon citratus capim-limão engenharia de processamento de produtos agricolas pós-colheita quality storage cymbopogon citratus plantas medicinais qualidade

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