Brazilian Journal of Chemical Engineering

URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/13554

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Improvement of soluble coffee aroma using an integrated process of supercritical CO2 extraction with selective removal of the pungent volatiles by adsorption on activates carbon
(Brazilian Society of Chemical Engineering, 2006-01-18) Lucas, S.; Cocero, M. J.
In this paper a two-step integrated process consisting of CO2 supercritical extraction of volatile coffee compounds (the most valuable) from roasted and milled coffee, and a subsequent step of selective removal of pungent volatiles by adsorption on activated carbon is presented. Some experiments were carried out with key compounds from roasted coffee aroma in order to study the adsorption step: ethyl acetate as a desirable compound and furfural as a pungent component. Operational parameters such as adsorption pressure and temperature and CO2 flowrate were optimized. Experiments were conducted at adsorption pressures of 12-17 MPa, adsorption temperatures of 35-50ºC and a solvent flow rate of 3-5 kg/h. In all cases, the solute concentration and the activated particle size were kept constant. Results show that low pressures (12 MPa), low temperatures (35ºC) and low CO2 flowrates (3 kg/h) are suitable for removing the undesirable pungent and smell components (e.g. furfural) and retaining the desirable aroma compounds (e.g. ethyl acetate). The later operation with real roasted coffee has corroborated the previous results obtained with the key compounds.
Extraction of caffeine, chlorogenic acids and lipids from green coffee beans using supercritical carbon dioxide and co-solvents
(Brazilian Society of Chemical Engineering, 2008-09-02) Azevedo, A. B. A.; Mazzafera, Paulo; Mohamed, R. S.; Melo, S. A. B. Vieira de; Kieckbusch, T. G.
The paper reports on experimental data on the extraction of caffeine, coffee oil and chlorogenic acids from green coffee beans using pure supercritical CO2 and supercritical CO2 modified with ethanol (5% w/w) and isopropyl alcohol (5% w/w) at 50 and 60ºC and 15.2 24.8 e 35.2 MPa. In this study extraction kinetics were obtained for all assays i.e. samples were collected at several time intervals for each solvent and mixed solvent. When pure CO2 and CO2-ethanol mixed solvent were used, an increase in pressure resulted in an increase in the amount of oil extracted. When CO2 was modified with isopropyl alcohol, the amount of coffee oil extracted also increased with pressure. Caffeine extraction initially increased and subsequently decreased with pressure. Chlorogenic acids were only extracted when isopropyl alcohol was used as a co-solvent. An increase in extraction temperature resulted in a decrease of caffeine and oil extraction (retrograde condensation) when only CO2 was used as solvent. With the use of co-solvent this retrograde behavior was no longer observed and the increase in temperature resulted in the increase in the extracted amounts of caffeine, coffee oil and chlorogenic acids.
Enzymatic Hydrolysis as an Environmentally Friendly Process Compared to Thermal Hydrolysis for Instant Coffee Production
(Brazilian Society of Chemical Engineering, 2016-10-26) Baraldi, I. J.; Giordano, R. L. C.; Zangirolami, T. C.
Conventional production of instant coffee is based on solubilisation of polysaccharides present in roasted coffee. Higher process temperatures increase the solubilisation yield, but also lead to carbohydrate degradation and formation of undesirable volatile compounds. Enzymatic hydrolysis of roasted coffee is an alternative to minimize carbohydrate degradation. In this work, products obtained from thermal and enzymatic processes were compared in terms of carbohydrates and volatiles composition. Roasted coffee was extracted with water at 125 °C, and spent coffee was processed by thermal (180 °C) or enzymatic hydrolysis. Enzymatic hydrolysis experiments were carried out at 50 °C using the commercial enzyme preparations Powercell (Prozyn), Galactomannanase (HBI-Enzymes), and Ultraflo XL (Novozymes). These formulations were previously selected from eleven different commercial enzyme preparations, and their main enzymatic activities included cellulase, galactomannanase, galactanase, and β-glucanase. Enzymatic hydrolysis yield was 18% (dry basis), similar to the extraction yield at 125 °C (20%), but lower than the thermal hydrolysis yield at 180 °C (28%). Instant coffee produced by enzymatic hydrolysis had a low content of undesirable volatile compounds and 21% (w/w) of total carbohydrates. These results point to the enzymatic process as a feasible alternative for instant coffee production, with benefits including improved quality as well as reduced energy consumption.
Effect of Ecofriendly Bio-Based Solvents on Oil Extraction From Green Coffee Bean and Its Industrial Press Cake
(Brazilian Society of Chemical Engineering, 2019-07-29) Oliveira, É. R.; Carvalho, G. R.; Cirillo, M. Â.; Queiroz, F.
Oil recovery, retention index, and thermodynamic parameters of green coffee beans (GCB) and its press cake (PC) extraction using bio-based solvents were investigated. The extraction parameters investigated were temperature (35 to 55 °C), type of material (coffee beans and press cake), and type of solvent (ethanol, acetone, and ethyl acetate), at a fixed solvent to solid mass ratio (5:1) (w/w). The fatty acid profile of the ethanolic extract was assessed for both GCB and PC, and compared to the oil obtained from the mechanical pressing. It was observed that higher temperatures affected positively the extraction yields, especially when acetone and ethanol were employed, allowing a recovery up to 90% and 56.7% for GCB and PC, respectively. The solution retained in the raffinate phase from the GCB extraction was greater than that for the PC. For all operational levels, the ∆H and ∆S were positive. ∆G decreased with increasing temperature. Palmitic and linoleic acids were predominant in all types of oil. The oil obtained by pressing showed higher content of linoleic acid (45.32%), while the solvent-extracted oil from GCB had more palmitic acid (34.79%), and the PC oil presented intermediate levels of all the methyl esters.