Mathematical models based on chemometric analyses of the coffee beverage sensory data and NIR spectra of 51 Arabica roasted coffee samples were generated aiming to predict the scores of acidity, bitterness, flavour, cleanliness, body and overall quality of coffee beverage. Partial least squares (PLS) were used to construct the models. The ordered predictor selection (OPS) algorithm was applied to select the wavelengths for the regression model of each sensory attribute in order to take only significant regions into account. The regions of the spectrum defined as important for sensory quality were closely related to the NIR spectra of pure caffeine, trigonelline, 5-caffeoylquinic acid, cellulose, coffee lipids, sucrose and casein. The NIR analyses sustained that the relationship between the sensory characteristics of the beverage and the chemical composition of the roasted grain were as listed below: 1 - the lipids and proteins were closely related to the attribute body; 2 - the caffeine and chlorogenic acids were related to bitterness; 3 - the chlorogenic acids were related to acidity and flavour; 4 - the cleanliness and overall quality were related to caffeine, trigonelline, chlorogenic acid, polysaccharides, sucrose and protein.

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In this work, the potential of mid‐infrared diffuse reflectance spectroscopy with Fourier transform for discrimination of 29 commercial Brazilian coffee samples with different industrial processing, i.e., caffeine extraction and roasting degree, was evaluated. The statistical treatments applied to pre‐treated spectral data were principal component analysis and partial least squares – discriminant analysis (PLS‐DA). The ordered predictors selection method was used for variable selection. The chemometric analyses of the mid‐infra‐red spectra allowed inferring on the lower carbohydrate, caffeine and chlorogenic acid concentration as well as on the higher water content in the decaffeinated coffee. The technique also allowed speculation on the higher lipid and lower water content in the dark roasted coffee compared with traditional roasted coffee. A clear discrimination of decaffeinated from medium and dark roasted coffees was observed in PC1. PLS‐DA was used for the discrimination between medium and dark roasted coffees. A model with one latent variable correctly classified 100% of the external validation and prediction samples according to their roasting degree. PRACTICAL APPLICATIONS Diffuse reflectance mid infrared spectroscopy (DRIFTS), principal component analysis and partial least squares were successfully applied to discriminate decaffeinated coffees from nondecaffeinated coffees and to discriminate roasted coffees by their roasting degree. This study have shown that DRIFTS coupled with chemometrics consists in a simple and straightforward analytical method for monitoring the roasted coffee authenticity, and the results could help in developing an alternative and inexpensive method for quality control of coffee products.

In this work, soft modeling based on chemometric analyses of coffee beverage sensory data and the chromatographic profiles of volatile roasted coffee compounds is proposed to predict the scores of acidity, bitterness, flavor, cleanliness, body, and overall quality of the coffee beverage. A partial least squares (PLS) regression method was used to construct the models. The ordered predictor selection (OPS) algorithm was applied to select the compounds for the regression model of each sensory attribute in order to take only significant chromatographic peaks into account. The prediction errors of these models, using 4 or 5 latent variables, were equal to 0.28, 0.33, 0.35, 0.33, 0.34 and 0.41, for each of the attributes and compatible with the errors of the mean scores of the experts. Thus, the results proved the feasibility of using a similar methodology in on-line or routine applications to predict the sensory quality of Brazilian Arabica coffee.

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There is an increasing demand for specialty coffees in the worldwide coffee market, which justifies the need for research focused on understanding the effect of genetic factors and environmental conditions on coffee quality. The aim of this study was to assess the occurrence of arabica coffee genotypes with a high potential for specialty coffee production under three different environmental conditions. Green coffee beans of arabica genotypes largely cultivated in Brazil were chemically evaluated: one Mundo Novo line and three Bourbon lines. The experimental sites were established in fields in three different municipalities (Lavras, Santo Antônio do Amparo and São Sebastião da Grama) located in Brazil. The level of sucrose and oxalic acid was a good discriminant marker for the beverage quality of the genotypes assessed, in which coffees with higher scores also showed higher levels of sucrose and lower levels of oxalic acid. Yellow Bourbon IACJ9 and the Yellow Bourbon/Origin SSP were indicated as the most suitable genotypes for specialty coffee production.

In this study we determined some properties of the cholesterol oxidase from a Brevibacterium strain isolated from buffalos milk and identified the cholesterol degradation products by the bacterial cell. A small fraction of the enzyme synthesized by cells cultured in liquid medium for 7days was released into the medium whereas a larger fraction remained bound to the cell membrane. The extraction of this fraction was efficiently accomplished in 1 mM phosphate buffer, pH 7.0, containing 0.7% Triton X-100. The enzyme stability under freezing and at 45 o C was improved by addition of 20% glycerol. The optimum temperature and pH for the enzyme activity were 53°C and 7.5, respectively. The only steroidal product from cholesterol oxidation by the microbial cell and by the crude extract of the membrane-bound enzyme was 4-colesten-3-one. Chromatographic analysis showed that minor no steroidal compounds as well as 4-colesten-3-one found in the reaction media arose during fermentation process and were extracted together with the enzyme in the buffer solution. Cholesterol oxidation by the membrane-bound enzyme was a first order reaction type.

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