Análise química e avaliação do potencial alelopático da casca do café (Coffea arábica)

• Autor(a) principal: Andrade, Aretha
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFU
• Texto Completo: https://repositorio.ufu.br/handle/123456789/17311
• topic: Café; Casca; Estudo químico; Alelopatia; Café - Resíduos; Coffee husk; Chemical composition; Antioxidant activity; Allelopaty evaluation; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA

In recent years different research groups are trying to find a regularity between the chemical analysis and various types of coffees selected through tasting. Besides the coffee beams selected for drinks that are most appreciated ( soft , gourmet, hard ) coffee husk are not discarded and much used by the roasted company. The add of roasted coffee husk (30-50%) allows the reduction of costs of coffee sold in the domestic market and are therefore routinely used in the composition of our daily coffee. This study aimed to examine and quantify the chemical constituents of coffee husk named mellow (bark of Coffea Arabica, without parchment, cultivar Mundo Novo) subjected to medium roasting, from Cerrado Mineiro. Although other studies are found in literature on the chemical composition of coffee husks there is not any scientific work that brings a detailed analysis of the chemical constituents of the shell (epicarp) and a comparison with the coffee (Coffea arabica). Thus, the analysis of macromolecular chemical composition of coffee husk by wet analysis, by spectroscopy in the ultraviolet (UV), by high performance liquid chromatography (HPLC) and by chemical composition of volatiles (mass spectrometry, MS) were made in comparision to that of coffee. Additionally, and viewing to a possible application of the bark of coffee in the coffee culture, it was studied its allelopathic action: the phytotoxic activity of dichloromethane extracts in pre-and post-emergent [germination of Panicum maximum (capim colonião)] treatment on growth of root and shoot, and analysis of secondary metabolites present in the dichloromethane extract of the bark of coffee. Chemical analysis of the roasted coffee husk revealed a well differentiated composition of roasted coffee bean. The results coming from insoluble solids (66.03% for coffee, 55.38% for coffee rusk) and aqueous extract (34.41% for coffee, 39, 46% for coffee rusk) of activity may suggest a taste very close, which explains the addition of the powdered coffee rusk of the coffee trade. Significant changes occurred in levels of all studied parameters: humidity (3.0% for coffee, 3.0% coffee rusk k), insoluble solids (66.03% for coffee, 55.38% for coffee rusk), aqueous extract (34.41% for coffee, 39, 46% for coffee rusk), the lipid content (11.62% for coffee, 4.52% for coffee rusk), Klason lignin (33.50% for coffee, 13.23% for coffee rusk), holocellulose (47.19% for coffee, 32.15% for coffee rusk), extractives methanol / water (34.41% for coffee, 39.46% for coffee rusk), phenolic compounds (75.99 mg mg-1 for coffee, 23.63 mg mg-1 for the coffee rusk), proanthocyanidins (16.52 mg mg-1 for coffee, 21.97 mg mg-1 for the shell), pH (5.23 for coffee, 4.21 for coffee rusk), caffeine (3.85% for coffee, 0.81% for coffee rusk l) and antioxidant activity (EC50 1,10 mg mg-1 of DPPH and coffee, 6,41 mg mg-1 of DPPH for coffee rusk), By presenting some compositions below the coffee beans (except lipid contents), the coffee husk has chemical characteristics undesirable for consumption. Evaluation of allelopathy in dichloromethane extracts of coffee husk, showed that the secondary metabolites were effective in inhibiting the development of the root (at a concentration of 100 mg mL-1), while inhibiting the development of the shoot allelopathy, the extract of coffee grounds was more efficient (at a concentration of 100 and 200 mg mL -1), a significant inhibition in the growth of roots and shoots of the weed Panicum maximum (capim colonião). Anyway, these results suggest the use of coffee husk as an adjunct to control weeds.