Separation and Purification Technology

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1 Seprtion nd Purifiction Technology 83 (2011) Contents lists vilble t SciVerse ScienceDirect Seprtion nd Purifiction Technology journl homepge: Extrction of ntioxidnt phenolic compounds from spent coffee grounds Solnge I. Musstto, Lin F. Bllesteros, Silvi Mrtins, José A. Teixeir Institute for Biotechnology nd Bioengineering (IBB), Centre of Biologicl Engineering, University of Minho, Cmpus de Gultr, Brg, Portugl rticle info bstrct Article history: Received 1 My 2011 Received in revised form 11 September 2011 Accepted 22 September 2011 Avilble online 1 October 2011 Keywords: Antioxidnt ctivity Extrction Methnol Phenolic compounds Spent coffee grounds The extrction of ntioxidnt phenolic compounds from spent coffee grounds (SCG) ws studied. Extrction experiments were crried out by the conventionl solid liquid method, using methnol s solvent t different concentrtions (20 100%), solvent/solid rtios (10 40 ml/, nd extrction times (30 90 min), nd the influence of these opertionl vribles on the content of totl phenolic compounds nd ntioxidnt ctivity of the produced extrcts ws evluted. Flvonoids, chlorogenic cid, nd protoctechuic cid were found in ll the produced extrcts nd were lso quntified. A strong influence (p < 0.05) of the vribles on the extrction results ws verified, nd the conditions ble to mximize ech response (contents of totl phenolic compounds, flvonoids, chlorogenic cid nd protoctechuic cid, nd ntioxidnt ctivity) were estblished. Extrction using 60% methnol in solvent/solid rtio of 40 ml/g SCG, during 90 min, ws the most suitble condition to produce extrct with high content of phenolic compounds (16 mg gllic cid equivlents/ nd high ntioxidnt ctivity (FRAP of 0.10 mm Fe(II)/g), simultneously. These findings re of interest since ntioxidnt phenolic compounds hve n outstnding role in helth re, nd wide pplictions in food nd phrmceuticl products. Ó 2011 Elsevier B.V. All rights reserved. 1. Introduction In the lst yers, the instnt coffee industry hs experienced constnt growth s instnt coffee hs become one of the most populr kinds of coffee drunk by million of people round the world. As consequence, lrge mounts of spent coffee grounds (SCG), which re the solid residues obtined during the processing of coffee powder with hot wter or stem to prepre instnt coffee, hve been generted worldwide (in the order of 6,000,000 tons/yer) [1,2]. Although the lrge vilbility nd composition rich in compounds of industril interest such s crbohydrtes, proteins, nd phenolic compounds [3], SCG hs not been used s rw mteril for other processes. Phenolic compounds hve received considerble ttention due to their beneficil effects on humn helth, such s protective ction ginst chronic degenertive diseses (ctrcts, mculr degenertion, neurodegenertive diseses, nd dibetes mellitus), cncer nd crdiovsculr diseses, nd others [4]; which hve been scribed to their ntioxidnt ctivity [5]. In recent study, extrcts produced from SCG exhibited nti-tumor nd nti-llergic ctivities, which were relted to the presence of phenolic compounds such s chlorogenic cid in their composition [6]. In fct, chlorogenic cid, which is one of the most bundnt phenolic compounds in SCG [6,7], hs been reported to hve number of beneficil helth properties relted to their potent ntioxidnt ctivity Corresponding uthor. Tel.: ; fx: E-mil ddresses: solnge@deb.uminho.pt, solngemusstto@hotmil.com (S.I. Musstto). s well s heptoprotective, hypoglycemic, nti-bcteril, ntivirl, nti-inflmmtory nd nti-crcinogenic ctivities [8,9]. Due to these importnt biofunctionlities, phenolic compounds hve found numerous pplictions in food nd phrmceuticl res. Extrcting ntioxidnt phenolic compounds from SCG cn be thus considered n interesting lterntive to obtin these importnt industril ingredients from low cost rw mteril, while dd vlue to SCG. Extrction is the first step in the isoltion of phenolic compounds from gro-industril residues nd plnt mterils. Different techniques hve been pplied to recover ntioxidnt phenolic compounds from nturl sources including solid liquid extrction with orgnic solvents, ultrsound-ssisted extrction, microwvessisted extrction, supercriticl fluids extrction, nd high pressure processes [10 12]. Among these techniques, solid liquid extrction is widely employed for phenolics extrction from vegetble sources. However, the efficiency of the extrction process is ffected by severl fctors such s the type of solvent nd its concentrtion, the solvent/solid rtio, the number of extrction steps, ph, time of contct, temperture, nd prticle size of the solid mtrix [13 15]. Thus, it is very importnt to optimize the extrction conditions in order to mximize the extrction efficiency to ech rw mteril. The objective of this study ws to extrct ntioxidnt phenolic compounds from SCG. Solid liquid extrctions were performed using methnol s solvent, due to its wide use in different processes, nd recognized efficiency for phenolic compounds extrction from plnt mterils. Additionlly, queous methnol hs high boiling point, nd is n economicl solvent [16]. Different /$ - see front mtter Ó 2011 Elsevier B.V. All rights reserved. doi: /j.seppur

2 174 S.I. Musstto et l. / Seprtion nd Purifiction Technology 83 (2011) methnol concentrtions, solvent/solid rtios, nd extrction times were studied, nd the effect of these opertionl vribles on the extrction results ws verified. Moreover, the conditions ble to produce phenolic rich extrct with high ntioxidnt ctivity were estblished. 2. Mterils nd methods 2.1. Smple mteril nd chemicls Spent coffee grounds (SCG) were supplied by NovDelt-Comércio e Indústri de Cfés S.A. (Cmpo Mior, Portugl). The mteril ws dried in n oven t 60 C until 5% moisture content nd stored for further extrctions. Phenolic stndrds including gllic cid, chlorogenic cid, protoctechuic cid, nd quercetin; methnol nd Folin Cioclteu phenol regent were purchsed from Sigm (Sigm Aldrich GmbH, Sternheim, Germny). All other chemicls used were of nlyticl grde nd obtined from either Sigm Aldrich or Merck (Drmstdt, Germny) Solvent extrction In first stge, the extrction experiments were performed using different conditions of methnol concentrtion (60 100%), solvent/solid rtio (10 30 ml/g), nd extrction time (30 90 min). The conditions used in ech experiment were settled ccording to the 2 3 full fctoril design presented in Tble 1. Subsequently, dditionl extrction experiments were performed by vrying the methnol concentrtion between 20% nd 80%, nd the solvent/solid rtio between 10 nd 40 ml/g SCG, during 90 min (Tble 2). For comprison, ssys using only distilled wter s extrction solvent were lso performed. For the rections, the extrction solvent nd the SCG were poured into 100-ml Erlenmeyer flsks, which were duly covered nd mintined during the desired time in wter-bth with mgnetic gittion t C. Subsequently, the totl content of ech flsk ws centrifuged (2500g, 4 C, 20 min) nd the superntnt (SCG extrct) ws filtered through 0.22 lm filters nd stored t 20 C in drkness until nlyses. The volume of extrct recovered fter ech extrction ws quntified nd used for clcultions. Tble 1 Experimentl conditions used to evlute the effect of process vribles (methnol concentrtion, time nd solvent/solid rtio) on the extrction of ntioxidnt phenolic compounds from SCG, composition nd ntioxidnt ctivity of ech obtined extrct. Assys ccording to 2 3 full fctoril design. Assy Process vribles rel nd (coded) vlues Methnol concentrtion (%) Time (min) Solvent/solid rtio (ml/g) Responses TP (mg GAE/ FRAP (mm Fe(II)/ 1 60 ( 1) 30 ( 1) 10 ( 1) (+1) 30 ( 1) 10 ( 1) ( 1) 90 (+1) 10 ( 1) (+1) 90 (+1) 10 ( 1) ( 1) 30 ( 1) 30 (+1) (+1) 30 ( 1) 30 (+1) ( 1) 90 (+1) 30 (+1) (+1) 90 (+1) 30 (+1) (0) 60 (0) 20 (0) (0) 60 (0) 20 (0) (0) 60 (0) 20 (0) (0) 60 (0) 20 (0) TP: totl phenolics; FRAP: ntioxidnt ctivity by the ferric reducing ntioxidnt power ssy Anlyticl methodology Determintion of totl phenolics The totl content of phenolic compounds in SCG extrcts ws determined by using the Folin Cioclteu regent ccording to the colorimetric method described by Singleton nd Rossi [17], dpted to 96-well microplte. Briefly, 5 ll of ech filtered extrct were mixed with 60 ll of sodium crbonte solution t 7.5% (w/v) nd 15 ll of Folin Cioclteu regent. Subsequently, 200 ll of distilled wter were dded nd the solutions were mixed. After tht, the smples were heted t 60 C for 5 min nd were llowed to cool t room temperture. The bsorbnce ws mesured by mens of spectrophotometric microplte reder set t 700 nm. A clibrtion curve ws mde from gllic cid stndrd solution (200, 400, 600, 800, 1000, 2000, 3000 mg/l) nd the blnk ws prepred with distilled wter. The totl content of phenolic compounds ws expressed s milligrm gllic cid equivlent per dry weight mteril (mg GAE/ Determintion of flvonoids Flvonoids in SCG extrcts were estimted using the colorimetric ssy previously described by Chng et l. [18] with some modifictions. A volume of 30 ll of ech filtered extrct ws dded in 96-well microplte nd subsequently, sequentil ddition of 90 ll methnol, 6 ll luminum chloride t 10% (w/v), 6 ll potssium cette (1 mol/l), nd 170 ll distilled wter to ech extrct smple ws performed. Smples were mintined during 30 min in the drk t room temperture. The bsorbnce of the mixture ws then mesured t 415 nm ginst blnk of distilled wter. A clibrtion curve ws prepred with stndrd solution of quercetin (25, 50, 100, 150, 200 mg/l). The content of totl flvonoids ws expressed s milligrm quercetin equivlent per dry weight mteril (mg QE/ Determintion of ntioxidnt ctivity The ntioxidnt ctivity of SCG extrcts ws mesured by the ferric reducing ntioxidnt power (FRAP) ssy, which ws performed ccording to the method described by Benzie nd Strin [19] with some modifictions. A 10 ll liquot of filtered extrct ws mixed with 290 ll of FRAP regent in 96-well microplte, nd incubted t 37 C for 15 min. After tht, the bsorbnce ws determined t 593 nm using distilled wter s blnk. A clibrtion curve ws constructed using n queous solution of ferrous sulfte (FeSO 4 7H 2 O t 200, 400, 600, 800 nd 1000 lm). The FRAP vlues were expressed s millimoles of ferrous equivlent per dry weight of mteril (mm Fe(II)/ Chlorogenic cid nd protoctechuic cid determintions Chlorogenic cid nd protoctechuic cid were nlyzed by high performnce liquid chromtogrphy (HPLC) on n equipment LC- 10 A (Jsco, Jpn) using UV detector t 276 nm nd Nucleosil C18 5 lm ( mm) column t room temperture. A mixture of cetonitrile nd wter (rtio 1/8) with 10 g/l of glcil cetic cid nd with the finl ph djusted to 2.5 with phosphoric cid ws used s mobile phse t flow rte of 0.9 ml/min. The solvent mixture ws degssed in n ultrsonic bth before to be used s mobile phse. The concentrtion of the phenolic cids ws determined from stndrd curves mde with known concentrtions of ech compound. The response of the UV detector ws recorded nd integrted using the D-7000 HPLC System Mnger softwre (Hitchi) Sttisticl nlyses The influence of the vribles methnol concentrtion, solvent/ solid rtio, nd time on the extrction of ntioxidnt phenolic

3 S.I. Musstto et l. / Seprtion nd Purifiction Technology 83 (2011) Tble 2 Experimentl conditions used for extrction of ntioxidnt phenolic compounds from SCG, composition nd ntioxidnt ctivity of ech obtined extrct. Assys ccording to 2 2 centrl composite design. Assy Process vribles rel nd (coded) vlues Responses Methnol concentrtion (%) Solvent/solid rtio (ml/ g) TP (mg GAE/ FLA (mg QE/ CGA (mg/ PCA (mg/ 1 20 ( 1) 10 ( 1) (+1) 10 ( 1) ( 1) 40 (+1) (+1) 40 (+1) ( 1) 25 (0) (+1) 25 (0) (0) 10 ( 1) (0) 40 (+1) (0) 25 (0) (0) 25 (0) (0) 25 (0) H 2 O H 2 O FRAP (mm Fe(II)/ TP: totl phenolics; FLA: flvonoids; CGA: chlorogenic cid; PCA: protoctechuic cid; FRAP: ntioxidnt ctivity by the ferric reducing ntioxidnt power ssy. compounds from SCG ws investigted through 2 3 full fctoril design nd 2 2 centrl composite design. The rel nd coded vlues of the vribles for the experimentl designs re given in Tbles 1 nd 2. Sttisticl significnce of the vribles ws determined t the 5% probbility level (p < 0.05). The dt obtined from the 2 2 experimentl design were fitted to second order polynomil equtions nd where possible the models were simplified by elimintion of sttisticlly insignificnt terms. Sttisticl significnce of the regression coefficients ws determined by Student s t- test, nd the proportion of vrince explined by the models were given by the multiple coefficient of determintion, R 2. Sttisticl nlysis of the dt s well s the determintion of the conditions ble to mximize the extrction results were performed using the softwres Sttistic (version 8.0), nd Design expert (version 5.0). Assys to vlidte the optimum extrction conditions s well s the nlysis for chrcteriztion of the produced extrcts were performed in triplicte. 3. Results nd discussion The solvent concentrtion, solvent/solid rtio, extrction time, nd temperture re key fctors in extrction processes, s they ffect both the kinetics of phenolics relese from the solid mtrix nd the ntioxidnt ctivity of the extrct. Therefore, this study consisted in evluting the effect of these vribles, nmely the solvent concentrtion, solvent/solid rtio, nd time on the recovery of ntioxidnt phenolic compounds from SCG. The temperture of extrction ws fixed between 60 nd 65 C, considering the boiling point of the methnol (64.7 C). The results obtined in these experiments re shown in Tble 1. Sttisticl nlysis of these dt reveled significnt influence (p < 0.05) of ll the studied vribles on the extrction results (totl phenolics nd ntioxidnt ctivity), which were improved when the methnol concentrtion ws decresed, nd the solvent/solid rtio nd time were incresed. In fct, the best results of totl phenolics nd FRAP were chieved in the conditions of the ssy 7 tht used methnol in concentrtion of 60% nd in rtio of 30 ml per g SCG, during 90 min (Tble 1). Aiming to mximize the extrction results nd to define the best conditions for ntioxidnt phenolic compounds extrction from SCG, new experimentl design ws proposed. In this new design, only the methnol concentrtion nd the solvent/solid rtio were studied. The extrction time ws fixed t 90 min since the use of longer times could not be economiclly dvntgeous. Methnol concentrtion ws then vried between 20% nd 80%, nd the solvent/solid rtio between 10 nd 40 ml/g SCG. Extrction conditions used in ech experimentl ssy nd the respective totl phenolics content nd ntioxidnt ctivity of the obtined SCG extrcts re shown in Tble 2. For comprison, ssys using only distilled wter s extrction solvent were lso performed; however, the use of methnol s solvent gve better extrction results thn the use of only wter. This could be explined by the fct tht phenolic compounds re often more soluble in orgnic solvents less polr thn wter [16,20]. Alcohols, prticulrly methnol nd ethnol, were lso more efficient thn wter in extrcting phenolics from different nturl sources such s citrus peel, blck te, brley, mshu tubers, nd medicinl plnts [15,21 23]. However, methnol is considered the best solvent for polyphenols extrction [24]. In the second experimentl design, the highest mount of phenolic compounds recovered by methnol extrction ws correspondent to n verge of 18 mg GAE/g SCG (ssys 9, 10 nd 11, Tble 2). This is high vlue, nlogous to the content reported in other importnt ntioxidnt sources such s ripe rspberry ( mg GAE/g dry mtter), blckberry ( mg GAE/g dry mtter) [25], nd lmond shells (22.0 mg GAE/g dry mtter) [26]. The ntioxidnt ctivity of the methnolic SCG extrcts (vrying from to mm Fe(II)/g SCG, Tble 2) ws lso higher thn the vlues reported to other nturl sources such s pple, per, pech, plum, nd kiwi [27]. Chemicl chrcteriztion of the SCG extrcts reveled tht ll of them contined chlorogenic cid, protoctechuic cid nd flvonoids in their composition (Tble 2), compounds tht re well described to hve ntioxidnt cpcity nd numerous biofunctionlities [9,28,29]. The high content of phenolic compounds (with presence of phenolic cids nd flvonoids) nd ntioxidnt ctivity of SCG extrcts revel tht SCG is potentil source to obtin ntioxidnt phenolic compounds. The composition of the methnolic SCG extrcts nd their ntioxidnt ctivity strongly vried ccording to the extrction conditions used (Tble 2). By vrying the extrction conditions, the totl phenolics nd flvonoids contents, s well s the ntioxidnt ctivity of the extrcts were incresed in lmost 3-fold. More significnt vritions were observed for the contents of chlorogenic nd protoctechuic cids, which incresed in the order of 4-fold. These results demonstrte tht the studied opertionl vribles exerted gret influence on the extrction of ntioxidnt phenolic compounds from SCG. In order to verify the effect of ech opertionl vrible in the responses, Preto chrts were plotted (Fig. 1). In this figure, brs extending beyond the verticl line corresponded to the effects sttisticlly significnt t 95% confidence level. As cn be noted, both vribles methnol concentrtion nd solvent/solid rtio exerted significnt influence (p < 0.05) in ll the evluted

4 176 S.I. Musstto et l. / Seprtion nd Purifiction Technology 83 (2011) Totl phenolic compounds b FRAP X1.X X1.X X1 (L) 0.05 X1 (L) p= Stndrdized Effect Estimte 0 p= Stndrdized Effect Estimte c Chlorogenic Acid 9.34 d Protocthecuic Acid X1 (L) 1.97 X1.X p= Stndrdized Effect Estimte X1 (L) 1.37 X1.X p= Stndrdized Effect Estimte e Flvonoids X1 (L) X1.X p= Stndrdized Effect Estimte Fig. 1. Preto chrt for the effects of methnol concentrtion (X 1 ), solvent/solid rtio (X 2 ), nd their interction (X 1,X 2 ) during the solid liquid extrction of spent coffee grounds, on the totl phenolic content (), ntioxidnt ctivity (b), chlorogenic cid (c), protoctechuic cid (d), nd flvonoids (e) contents in the produced extrcts. L nd Q correspond to the effects t liner nd qudrtic levels, respectively. Tble 3 Polynomil equtions fitted to the experimentl dt of composition nd ntioxidnt ctivity of spent coffee grounds extrcts, nd their respective regression coefficients R 2. Response Model eqution R 2 Totl phenolic compounds (TP, in mg GAE/ TP = X X X Antioxidnt ctivity (FRAP, in mm Fe(II)/ FRAP = X X X X 1X Chlorogenic cid (CGA, in mg/ CGA = X X X Protoctechuic cid (PCA, in mg/ PCA = X X X Flvonoids (FLA, in mg QE/ FLA = X X X X 1 X X 1 : methnol concentrtion; X 2 : solvent/solid rtio. Coded vlues. responses. The solvent/solid rtio ws the most importnt vrible ffecting the ntioxidnt ctivity of the extrcts (Fig. 1b), s well s the extrction of chlorogenic nd protoctechuic cids (Fig. 1c nd d); wheres methnol concentrtion ws the min vrible responsible for the extrction of phenolic compounds nd flvonoids (Fig 1 nd e). The methnol concentrtion ws lso n importnt vrible contributing to the extrction of phenolic compounds from other nturl sources, such s mshu tubers, for exmple [15]. Mthemticl models describing the responses vritions s function of the vritions in the methnol concentrtion nd solvent/solid rtio were estblished (Tble 3). Where possible, the models were simplified by elimintion of sttisticlly insignificnt terms (with p>0.05). All the models were estblished with high coefficient of determintions R 2, rnging from 0.91 to 0.97, which mens close greement between the experimentl results nd those predicted by the models. These models could efficiently be used for rpid prediction of the extrction results to be chieved

5 S.I. Musstto et l. / Seprtion nd Purifiction Technology 83 (2011) results thn when using pure orgnic solvent [15,30,31]. On the other hnd, the use of wter s only solvent gives lower extrction vlues nd yields, s before explined [16,20]. A three-dimensionl surfce ws lso plotted for the results of ntioxidnt ctivity in SCG extrcts (Fig. 2b). When compring this plot with tht obtined for the results of totl phenolic compounds (Fig. 2), it is possible to visulize tht the region where the responses re mximized is not exctly the sme in both figures. However it would be very useful to find n optimum extrction condition ble to yield extrcts with elevted content of phenolic compounds nd ntioxidnt ctivity. Considering this spect, grphicl optimiztion bsed on overlying the curves of these two responses ws conducted in order to estblish n extrction condition to simultneously mximize the totl content of phenolic compounds nd ntioxidnt ctivity of the SCG extrcts. To find this optimum condition, the following criteri ws imposed: totl phenolic content P16 mg GAE/g SCG, nd FRAP P0.095 mm Fe(II)/g SCG. The overlying plot ttined (Fig. 3) shows n re where the imposed criteri re stisfied. A point ws ssigned in this re (mrked by the squre) s optimum point, which corresponded to the use of 60% methnol concentrtion in solvent/ solid rtio of 40 ml/g. Under these extrction conditions, SCG extrcts with totl phenolic content of 16 mg GAE/g SCG, nd FRAP of 0.10 mm Fe(II)/g SCG, in the confidence rnge of 95%, cn be obtined. Similr methnol concentrtion (60%) hs lso been used for extrcting phenolic compounds from other nturl sources, providing better extrction results thn other methnol wter mixtures [32 35]. Assys to vlidte the optimum extrction conditions were performed nd the results obtined for totl phenolic compounds nd ntioxidnt ctivity of the extrct reveled close greement with the results predicted by the sttisticl nlysis (Tble 4). Additionlly, the contents of flvonoids, chlorogenic nd protoctechuic cids tht cn be obtined under these optimized conditions were lso determined, nd corresponded to 1.81 mg QE/g SCG, 1.24 mg/g SCG, nd 0.21 mg/g SCG, respectively. Fig. 2. Response surfces described by the models representing the totl phenolics content () nd ntioxidnt ctivity FRAP (b) of spent coffee grounds extrcts obtined by extrction with methnol. The vribles re presented in their originl levels. when using methnol concentrtions nd solvent/solid rtios in the rnge of vlues here studied. All the mthemticl models describing the responses vritions presented liner (L) nd qudrtic (Q) terms, since both vribles levels presented sttisticl significnce t p < 0.05, s shown in Fig. 1. The qudrtic term for methnol concentrtion ws the most significnt for the response of totl phenolic compounds (Fig 1) nd presented negtive signl. This mens tht the extrction results were not linerly incresed when the methnol concentrtion ws decresed, but there ws n optimum point fter which the use of lower methnol concentrtions did not improve the extrction results. Such behvior cn be well visulized through the three-dimensionl surfce plot presented in Fig. 2. This surfce describes the vritions of the response s function of the vritions of the vribles, in the studied rnge of vlues. As cn be observed, the solvent concentrtion decrese ws beneficil for the extrction of phenolic compounds but up to ttin certin limit, fter which the extrction efficiency ws reduced. In fct, the use of wter in combintion with orgnic solvent hs been reported to contribute to the cretion of modertely polr medium tht insures the extrction of phenolics, giving better SOLVENT / SOLID RATIO (ml / g) FRAP: TP: 16 X: 60 Y: 40 TP: 16 FRAP: METHANOL CONCENTRATION (%) Fig. 3. Optimum region by overlying the curves of the responses totl phenolics content (TP) nd ntioxidnt ctivity (FRAP) s function of the methnol concentrtion nd solvent/solid rtio used for spent coffee ground extrction.

6 178 S.I. Musstto et l. / Seprtion nd Purifiction Technology 83 (2011) Tble 4 Results obtined in the ssys for vlidtion of the conditions optimized for extrction of ntioxidnt phenolic compounds from spent coffee grounds. Assys for vlidtion of the optimized conditions 4. Conclusions Solid liquid extrction using methnol s orgnic solvent ws n efficient method to extrct ntioxidnt phenolic compounds from spent coffee grounds. The extrction of totl phenolics, flvonoids, chlorogenic nd protoctechuic cids, s well s the ntioxidnt ctivity of the produced extrcts were ffected by the methnol concentrtion, solvent/solid rtio, nd extrction time used. Mximum vlue of phenolic compounds extrcted from SCG were correspondent to 18 mg GAE/g SCG, nd were obtined when using methnol concentrtion of 50% v/v in rtio of 25 ml per g of SCG, during 90 min. Optimiztion of the extrction conditions (methnol concentrtion of 60% in solvent/solid rtio of 40 ml/g, during 90 min) ws useful to produce extrcts contining simultneously high content of phenolic compounds (16 mg GAE/g SCG, correspondent to n extrction yield of 89% considering the mximum phenolic compounds concentrtion found in SCG) nd high ntioxidnt ctivity (0.10 mm Fe(II)/. Since ntioxidnt compounds provide helth benefits, spent coffee grounds extrcts could be of gret interest for ppliction in food nd phrmceuticl products. However, it merits emphsizing tht lthough methnol is the most commonly used extrction solvent due to its high polrity nd high extrction yields, the toxic chrcteristic of this solvent rises serious issues when the purpose of the compounds extrcted with this solvent is the ppliction in food nd phrmceuticl industries. To overcome this problem, the next step of our reserch work will be focused on finding other less or non-toxic solvents for extrction, ble to promote high extrction results s methnol, or even using bioprocesses such s the solidstte fermenttion, which do not require the ppliction of ny orgnic solvent. The use of methnol in the present study ws useful to estblish the mximum mount of phenolic compounds tht ws present in SCG, nd lso to verify the possibility of obtining ntioxidnt phenolic extrcts from this gro-industril residue. Acknowledgment This work ws supported by the Portuguese Foundtion for Science nd Technology (FCT). References Process vribles optimum point vlues Methnol (%) Solvent/ solid rtio (ml/g) Responses TP (mg GAE/ FRAP (mm Fe(II)/ Averge Results predicted by the sttisticl nlysis TP: totl phenolics; FRAP: ntioxidnt ctivity by the ferric reducing ntioxidnt power ssy. [1] S.I. Musstto, E.M.S. Mchdo, S. Mrtins, J.A. 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