Abstract
Brazil is the largest producer of coffee in the world and coffee prices are directly linked to grain quality. In this work, the antioxidant activity of coffee was related to its quality through Electron Spin Resonance Spectroscopy (ESR), as an attempt to establish a non-subjective method to classify the grain quality. For that purpose, the IC50 and temporal monitoring of its non-oxidized fraction were determined for three bean qualities: Soft (High), Hard (Medium) and Rio (Low). Methanolic solution of 2,2-difenil-1-picril-hidrazila (DPPH), that has a stable radical and a JEOL FA-200 (X-Band) spectrometer were used for these tests. The temporal monitoring of reaction between radical and coffee was performed. The rate of reduced or of antioxidated radicals was determined on time and for each coffee beverage quality were found different slopes of curve: Soft (0.32±0.02), Hard (0.47±0.02) and Rio (0.60±0.02). The IC50 result of Rio quality (2.7 ± 0.9) was different from the Soft (7.8 ± 1.9) and Hard (6.5 ± 1.5) values, but there was no difference between the High and Medium results due to the uncertainty associated. Therefore the results found, mainly for monitoring temporal, establish a new quantitative methodology for classifying the coffee beverage quality.
Highlights
Coffee has a huge economic importance to Brazil and other producer countries, since it is the second largest item of trade in the international market, with Brazil being the largest producer (NACIF, 2003)
We propose a simple method to differentiate the beverage quality through Electron Spin Resonance Spectroscopy (ESR) spectroscopy without using ionizing radiation
Samples of green coffee (Coffea Arabica L.) from the 2010/11 crop season in southern Minas Gerais were provided by SAAG (Sociedade de Armazenamento e Agricultura) at the request of Dr Flavio Meira Borém of the University of Lavras (UFLA)
Summary
Coffee has a huge economic importance to Brazil and other producer countries, since it is the second largest item of trade in the international market, with Brazil being the largest producer (NACIF, 2003). The search for new technologies that can improve the selection of this product is of great economic value. In the Brazil, the coffee quality is assessed, among other analyzes (sieving, defects, color), by classification of the beverage based on the sensorial analysis standardized by the Brazilian Secretary of Agriculture (Ministério da Agricultura, Pecuária e Abastecimento) (BRASIL, 2003). The test consists of pouring boiling water (150mL) over roasted and ground coffee (10g, specific roast and fine grind). The mixture classification is made by performing a sensory evaluation with determination of the combination of smell and flavor (FARAH et al, 2006). This characteristic is the result of growth, maturation, harvesting and the post- harvesting processing
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