Selection of the solvent and extraction conditions for maximum recovery of antioxidant phenolic compounds from coffee silverskin

The extraction of antioxidant phenolic compounds from coffee silverskin (CS) was studied. Firstly, the effect of different solvents (methanol, ethanol, acetone, and distilled water) on the production of antioxidant extracts was evaluated. All the extracts showed antioxidant activity (FRAP and DPPH assays), but those obtained with methanol and ethanol had significantly higher (p < 0.05) DPPH inhibition than the remaining ones. Due to the lower toxicity, ethanol was selected as extraction solvent, and further experiments were performed in order to define the solvent concentration, solvent/solid ratio, and time to maximize the extraction results. The best condition to produce an extract with high content of phenolic compounds (13 mg gallic acid equivalents/g CS) and antioxidant activity [DPPH = 18.24 μmol Trolox equivalents/g CS and FRAP = 0.83 mmol Fe(II)/g CS] was achieved when using 60 % ethanol in a ratio of 35 ml/g CS, during 30 min at 60–65 °C.This work was supported by the Portuguese Foundation for Science and Technology (FCT). The authors gratefully acknowledge Teresa Conde, student of Biological Engineering, for the help and interest in this work

Chemical, functional, and structural properties of spent coffee grounds and coffee silverskin

Spent coffee grounds (SCG) and coffee silverskin (CS) represent a great pollution hazard if discharged into the environment. Taking this fact into account, the purpose of this study was to evaluate the chemical composition, functional properties, and structural characteristics of these agro-industrial residues in order to identify the characteristics that allow their reutilization in industrial processes. According to the results, SCG and CS are both of lignocellulosic nature. Sugars polymerized to their cellulose and hemicellulose fractions correspond to 51.5 and 40.45 % w/w, respectively; however, the hemicellulose sugars and their composition significantly differ from one residue to another. SCG and CS particles differ in terms of morphology and crystallinity, but both materials have very low porosity and similar melting point. In terms of functional properties, SCG and CS present good water and oil holding capacities, emulsion activity and stability, and antioxidant potential, being therefore great candidates for use on food and pharmaceutical fields.The authors acknowledge the financial support of the Science and Technology Foundation of Portugal (FCT) through the grant SFRH/BD/80948/2011 and the Strategic Project PEst-OE/EQB/LA0023/2013. The authors also thank the Project "BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes", REF. NORTE-07-0124-FEDER-000028 co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. Thanks are also given to Prof. Jose J.M. Orfao, from the Department of Chemical Engineering, Universidade do Porto (Portugal), for his assistance with the porosity analyses

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass—carbohydrates, lipids, and proteins—there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage

Application of the method of continued fractions to electron scattering by polyatomic molecules

A new computational code based on the method of continued fractions is developed to study low-energy electron scattering by polyatomic molecules with arbitrary symmetry. As a first application, this code is used to study elastic electron scattering by four representative molecules with different symmetries, viz., H-2, CH4, H2O, and NH3. The calculated physical quantities such as reactance K matrices, differential cross sections, etc, converge rapidly. Also, our calculated cross sections are in good agreement with other available theoretical and/or experimental data, confirming that this is an efficient method for studying electron molecule scattering. (C) 2001 Elsevier Science S,V. All rights reserved.1364167111712

A theoretical study on the photoionization of the valence orbitals of phosphine

We report a theoretical study on the photoionization of phosphine in the static-exchange level and frozen core approximation, using the method of continued fractions. The main subject of the present study is to investigate in which extent the Hartree-Fock description of the target applied to molecular photoionization is valid. Also, the role played by multichannel coupling is analysed. Our study shows that single-channel Hartree-Fock calculations can provide reliable results except for photon energies near the photoionization threshold.17116216

Extension of the method of continued fractions to molecular photoionization: an application to ammonia

A computational code based on the method of continued fractions, previously developed by our group for electron-molecule scattering calculations, is extended to treat photoionization of molecules of arbitrary symmetry. This new computational code is applied to study the photoionization of the two outermost valence orbitals of ammonia in the exact static-exchange level of approximation. The method has proved to be very accurate and rapidly convergent. Our results obtained for cross sections agree well with both experimental and theoretical results available in the literature.36173621362

Cross sections and polarization fractions for elastic e(-)-O-2 collisions

The Schwinger variational iterative method and the distorted-wave approximation are combined to study elastic electron scattering by O-2 for incident energies ranging from 5 to 500 eV. Differential, integral, and momentum transfer cross sections as well as polarization fractions are reported. A complex optical potential, which accounts for the static, exchange, correlation-polarization, and absorption contributions is used to describe the electron-molecule interaction. Comparison of our calculated results with experimental and other theoretical results is encouraging. [S1050-2947(99)08508-X].6021199120