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Neapolitan coffee brew chemical analysis in comparison to espresso, moka and American brews.
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  Neapolitan coffee brew chemical analysis in comparison to espresso,moka and American brews Nicola Caporaso, Alessandro Genovese ⁎ , Mariana D. Canela, Alberto Civitella, Raffaele Sacchi Department of Agriculture, University of Naples Federico II, Via Università 100, 80055 Portici, NA, Italy a b s t r a c ta r t i c l e i n f o  Article history: Received 17 October 2013Received in revised form 4 January 2014Accepted 9 January 2014Available online 16 January 2014 Keywords: Coffee aroma Coffea arabica Filtered coffeeAntioxidant activityCaffeineVolatile compounds TheaimofthepresentstudywastocharacterizethechemicalcompositionofNeapolitancoffeebrewincompar-isontoespresso,American,andmokacoffeebrews.DespitethesimilarityofbrewingprincipleofNeapolitanandAmerican coffee-making techniques, i.e. percolation of hot water through ground coffee, the characteristics of Neapolitan coffee brew in terms of antioxidant activity, total phenolic compounds and total solids were moresimilar to moka coffee brew. Espresso and moka showed higher antioxidant activity, and espresso exhibitedhighercaffeineconcentration,totalphenoliccompounds,andtotalsolidswithrespecttoothercoffeebrewsstud-ied. For the  󿬁 rst time a characterization of the Neapolitan coffee aroma, a traditional Italian brewing procedure,wasreported.Asigni 󿬁 canthigheramountinhexanal, β -damascenoneandsomepyrazineswasfoundinNeapolitancoffeearomawithrespecttootherprocedures.Thesecompoundscouldbeconsideredasadistinctivecharacteristicof Neapolitan coffee aroma. Moka was characterized by higher guaiacol content with respect to other procedures,while espresso showed signi 󿬁 cantly higher levels in aldehydes and 2-furanmethanol acetate.© 2014 Elsevier Ltd. All rights reserved. 1. Introduction Coffee is one of the most appreciated beverages in the world and,generally, its aroma is considered as one of the most important attri-butes. Among coffee botanical species, the arabica one ( Coffea arabica )has been reported as the most aromatic cultivar and it is commonlyused for the production of superior quality coffee brews. Developmentof aroma compounds is greatly dependent upon roasting degree andin particular on time – temperature conditions (Baggenstoss, Poisson,Kaegi,Perren,&Escher,2008),butthebrewingmethodisalsoofcrucialimportance(Rocha,Maeztu,Barros,Cid, & Coimbra,2003).So farabout800volatilecompoundshavebeenreportedingreenandroastedbeansand in coffee brews, mainly in  󿬁 ltered and espresso (Flament, 2002).The latter one has been described to be the most aromatic brew(Gloess et al., 2013; López-Galilea, Fournier, Cid, & Guichard, 2006;Rocha et al., 2003).Coffeeconsumptionhasbeenrelatedtomanyhealthbene 󿬁 ts,duetoits strong antioxidant activity and inhibition of lipid peroxidation(Napolitano, Fogliano, Tafuri, & Ritieni, 2007). Coffee also possessesprotective effects against therisk of advanced liver diseaseand hepato-cellular carcinoma, and coffee consumption protects the liver from dam-age caused by high-fat diet through different mechanisms (Vitaglioneetal.,2010).HumantrialsconsideringtheItalianconsumeraveragecoffeeintake (5 cups of espresso per day) found that coffee was able to signi 󿬁 -cantly increase plasma glutathione concentration (Esposito et al., 2003).This effect has been attributed to diterpenes, particularly cafesterol,whereas several other biologically active substances are found in coffee,suchaspolyphenolsandmelanoidins(Ferruzzi,2010).Theconcentrationof these compounds is affected by the type and srcin of ground coffee,its roasting degree (Sacchetti, Di Mattia, Pittia, & Mastrocola, 2009) andbrewing procedure (Ludwig et al., 2012; Niseteo, Komes, Bel šč ak-Cvitanovi ć , Hor ž i ć , & Bude č , 2012).Melanoidins are non-volatile, brown colored compounds in coffeebeans and brews, produced by the Maillard reaction (MR). Their con-centration in coffee brews increases with increasing roasting intensityand they play an important role on the total antioxidant activity(Borrelli, Visconti, Mennella, Anese, & Fogliano, 2002; Liu & Kitts,2011; Perrone, Farah, & Donangelo, 2012; Vignoli, Caldeira Viegas,Gentil Bassoli, & De Toledo Benassi, 2013).Different preparation methods are commonly used for coffee brewpreparation, and their distribution varies worldwide depending on tra-ditions, personal preferences, social behavior and many other factors.Although the most common coffee brewing technique is the  󿬁 lteredone, espresso coffee has gained popularity worldwide, while mokapreparation method is almost unknown and restricted to a domesticlevel in southern European countries such as Italy and Spain (Pérez-Martínez, Caemmerer, De Peña, Cid, & Kroh, 2010). Different prepara-tion techniques involve different polyphenol extraction, caffeine con-tent, total solid content, antioxidant activity level and volatile pro 󿬁 le Food Research International 61 (2014) 152 – 160 ⁎  Corresponding author. Tel.: +39 081 2539319; fax: +39 081 7762580. E-mail address:  alessandro.genovese@unina.it (A. Genovese).0963-9969/$  –  see front matter © 2014 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.foodres.2014.01.020 Contents lists available at ScienceDirect Food Research International  journal homepage: www.elsevier.com/locate/foodres  that greatly varies among the different brewing methods (López-Galilea,DePeña,&Cid,2007).Eachbrewingtechniqueappliesdifferentwater/groundcoffeeratios,watertemperatureandextractiontime,anddifferent water pressures or  󿬁 nal volumes (Petracco, 2001). In fact, asingle servingvolume, or  “ cup ” , is enormously variable in different cul-tures, ranging from 15 mL of concentrated espresso in Sicily to over250 mLof  󿬁 lteredcoffee in theUSA (Clarke & Vitzthum,2001). Thedif-ferentbrewingtechniquesarelinkedtolocaltraditionsandtheirnamesare usually given from their geographical srcins of traditional use.The Neapolitan coffee is a simple infusion method based on gravity,andhotwaterisallowedtopercolatethroughalayerofmedium-coarsegroundcoffee.The macchinetta napoletana  (Neapolitanpot,alsoknownas  “ 󿬂 ip drip pot ” ) has been used in Italian tradition since the 󿬁 rst yearsof 1800 (Petracco, 2001). Although the antioxidant activity, caffeine,total phenolic compounds, and volatile composition have been widelystudied, mainly in espresso and  󿬁 ltered coffee (Andueza et al., 2003;Gloess et al., 2013; López-Galilea et al., 2006, 2007; Maeztu et al.,2001;Sánchez-González,Jiménez-Escrig,&Saura-Calixto,2005;Santiniet al.,2011),noinvestigationreportsdataaboutthearomaofNeapolitancoffee brew.Thus, the aim of the present paper was to characterize the chemicalcomposition of Neapolitan coffee brew in comparison to espresso,American, and moka coffee brews. 2. Material and methods  2.1. Standards and coffee samples Authentic reference chemical compounds were obtainedfrom Sigma-Aldrich (Steinheim, Germany), Aldrich (Steinheim,Germany), and Fluka (Buchs, Switzerland). Acetaldehyde (99.5%),2-methylpropanal (99%), 2-methylbutanal (95%), 3-methylbutanal(97%), hexanal (98%), 2-ethyl-6-methylpyrazine (95%), 2-ethyl-5-methylpyrazine (97%), 2-propylpyrazine (97%), 2-ethyl-3,5-dimethylpyrazine (47.5%), 2,5-dimethylfuran (99%), furfurylmethylsul 󿬁 de (97%), 2-furanmethanol acetate (99%), 2-furanmethanol (98%),guaiacol (98%), 4-ethylguaiacol (98%), 4-vinylguaiacol (98%), 2,3-pentanedione (97%), methanethiol (98%) and caffeine (98.9%) wereobtained from Sigma-Aldrich. Butanal (99%) was obtained from Fluka,and  β -damascenone (1%, ethanol) was obtained from Aldrich. A com-mercial sample of ground roasted Arabica coffee blend, packaged inprotective atmosphere was provided by  Toraldo caffè  (Naples, Italy).The coffee sample consisted of a batch of Arabica 100% coffee,medium-high level of roasting. According to the information given bythe industry, coffee beans were thermally treated for about 17 min ata maximum temperature of 227 °C, for the roasting process. Theroasting degree indicated as Agstron Classi 󿬁 cation System was about25 IR (dark roast), and the particle size (granulometry) was 0.35 mm.The samples were produced in February2013, stored at room temper-ature and were used within two months from their production. Thesamples were stored in individual aluminum packages (7 g each),packedunderNitrogenprotectiveatmospheredirectlyfromtheindus-try, to avoid any oxidation or deterioration of the product. Moreover,each package was open immediately before each extraction processor each replicate of the brewing step procedure.  2.2. Coffee brew preparation Several coffee-brewing procedures were compared and the follow-ing machines were used: American coffeemaker, Neapolitan pot, mokapot, and espresso machine. The ground coffee/brew ratio was choseninaccordancetothebestindicationsfoundinliteratureandtothetradi-tional practices based on Italian coffee-making tradition. The main dif-ference to be underlined with respect to literature data consists on theamount of ground coffee used in moka and Neapolitan brews. Formoka procedure we used a higher amount of coffee ground, whichwasabundantinthe 󿬁 lter,butitwasnotpressed.Theprocessofextrac-tionwasrepeatedthreetimesforeachtypeofcoffeebrew.Theprepara-tion of the different coffee brews is reported as follows.  2.2.1. American coffee brew Thiscoffeebrewconsistsofaglassresistantkettleandaspecial 󿬁 lterwhere ground coffee is added as desired by the consumer. The appara-tusletthehot water percolate through the 󿬁 lter and coffee brew is col-lected in the kettle. American coffee brew, also called  󿬁 ltered coffeebrew, was prepared from 25 g of ground-roasted coffee and a volumeof 300 mL of distilled water. The obtained  󿬁 nal volume of coffee brewwas 230 mL and extraction took about 2 min (about 90 °C), by using a 󿬁 lter coffee machine Mr. Coffee model ARX23 (Sunbead Products Inc.,Boca Raton, FL, USA).  2.2.2. Neapolitan coffee brew The  macchinetta napoletana  (also known as  ‘ 󿬂 ip drip pot ’ ) is one of the simplest brewing methods based on infusion, and it was alreadyknown as an Italian tradition in the  󿬁 rst years of 1800. It uses gravityfor the percolation of hot water through a bed of medium-coarseground coffee. The main difference between drip  󿬁 lter and Neapolitanextractionmethodsisthatinthelatterthegroundcoffeeisimmobilizedbetween two  󿬁 ltering perforated plates, preventing the movement of thegranulesinthewater(Petracco,2001).IntheItalianandparticularlyintheNeapolitancoffee-makingtradition,thegroundcoffee/waterratioishigherwithrespecttothatusuallyadopted.Morespeci 󿬁 cally,thecof-fee powder is added in the coffee pot without pressing it but using ahigher amount with respect to the pot capacity, and this could changethe porosity and the internal pressure during theextraction procedure.The Neapolitan coffee machine consists of a special coffeepot madeof aluminum. In the lower part of the apparatus, a tank is  󿬁 lled withwater, the  󿬁 lter is added and  󿬁 lled with ground coffee and the upperpart is closed. A check valve existing in the coffeepot allows to verifywhen the water starts boiling. The coffeepot is rapidly overturned andthe water is allowed to percolate through the  󿬁 lter, that consists onlyof a metallic punched chamber. Immediately after overturning it, thelong coffeepot spout is traditionally covered by a homemade paper-cup,to avoid losing coffee aroma: this is called  cuppetiello  in the Neapolitanlanguage. The coffee brew is  󿬁 nally collected in the lower part of the ap-paratus. Neapolitan coffee brew was prepared from 15.4 g of ground-roasted coffee and a volume of 145 mL of distilled water. The obtained 󿬁 nal volume of coffee brew was about 75 mL and the extraction timewas about 5 min. Water temperature was about 90 °C at the beginningof brewing process and raised about 60 °C when  󿬁 ltration  󿬁 nished. Thecoffeepot used was the ILSA Tz.1 (Torino, Italy).  2.2.3. Moka coffee brew Mokais themost used coffee brew preparation technique in Italy atdomestic level,and this coffee has been oneof the most consumed alsoinothercountries.Pressureisappliedtothewaterbysimplyboilingitinanautoclave-typealuminum or steel kettle on anopen 󿬂 ame, and forc-ing it through an immersed pipe across the coffee cake formed in astrainer basket. The beverage is conveyed through appropriate tubinginto an upper vessel, screwed and sealed by a rubber gasket to thebase kettle. Contact time mainly depends on the cake hydraulic resis-tance,whichinturnhangsonthreefactors:theamountofgroundcoffeeused, its particle size distribution (grinding  󿬁 neness) and the tampingforce exerted on it, whether deliberately or just by forcing down aheap of coffee while fastening the top part (Petracco, 2001). The appa-ratusconsistsofametallictankbaseusedasawaterboilerandametal-lic  󿬁 lter where ground coffee is put. The upper part of the device is acylindrical cooler, tightly screwed onto the base, where the coffeedrink is quickly cooled and then collected before the use. Boilingwater is forced and then it  󿬁 lters through the coffee grounds into theupper section of the coffeepot where the coffee is collected. The mokacoffee brew was prepared from 11.3 g of ground-roasted coffee and a 153 N. Caporaso et al. / Food Research International 61 (2014) 152 – 160  volumeof80mLofdistilledwaterbyamokamachinemodelDamaST/C5(Bialetti Industrie SpA, Coccaglio, BS, Italy). Also in this preparation, likethe Neapolitancoffee ,thecoffeepowderisaddedinthecoffeepotwithoutpressinginanamounthigherwithrespecttothepotcapacity.Theobtain-ed 󿬁 nalvolumeofcoffeebrewwas62mLandextractiontookabout3min(above 100 °C). For moka and Neapolitan preparations, the  󿬂 ame of gascooker was maintained very low to reduce the coffee burning, as thishas been largely considered an important parameter for a  “ good Italiancoffee ”  production.  2.2.4. Espresso coffee brew Espresso is a preparation technique based on pressure induced per-colationofa limited amountofhotwaterthroughagroundcoffeecake,where the energy of water pressure is spent within the cake itself.Espresso coffee is prepared with a special machine that uses hot waterand high pressure for a short time (25 s) to produce a  “ short ”  coffeebrew (25 mL) with a distinctive cream layer on top (about 2 mL). Theespressocoffeebrewswerepreparedfrom7gofground-roastedcoffee,usingan Espresso machinemodel Pinocchio C(Spinel s.r.l., Parabita, LE,Italy). The speci 󿬁 cs of the machine and the brewing procedure werechosen in accordance to those reported by Caprioli et al. (2012). Thethermostatwassetbytheproducerat95 °Candtheactualtemperatureof water measured during extraction was about 93 °C. The pump pres-sure was set at 15 bar, and the outlet pressure measured was about9.5 bar.  2.3. Determination of pH and total solids Afterthebrewingprocess,sampleswererapidlycooledat20 °C,andthe pH was measured using a pH-meter. Total solids were determinedby oven drying 10 mL of different coffee brews to a constant weight,for 24 h at 100 °C. The analyses were performed in triplicate for eachbrewing procedure.  2.4. Total phenolic compounds TotalphenoliccompoundsweremeasuredusingtheFolin – Ciocalteureagent according to the method described by Bravo, Monente, Juániz,De Peña, and Cid (2013) for coffee brews analysis. After dilution (3:10v/v),theFolin – Ciocalteureagentwasaddedtostartthereactionandab-sorbance was taken after 2 min at 765 nm using a spectrophotometerUV-1601 (Shimadzu, Kyoto, Japan). Gallic acid was used as a standardfor the calibration curve. The analyses were performed in triplicate foreach brewing procedure.  2.5. Antioxidant activity by ABTS  + method The ABTS antioxidant capacity was performed according to themethod reported by Bravo et al. (2013). The only modi 󿬁 cation wasthe use of ABTS + radical prepared in aqueous solution instead of ethanol one as reported by Del Castillo, Ames, and Gordon (2002).This modi 󿬁 cation was made to avoid precipitation of coffee compo-nents that would have occurred in the ethanol environment. In fact,ABTS + has been reported to possess higher ef  󿬁 ciency in aqueous so-lution with respect to ethanol solution for coffee brew analysis, duetothe highersolubilityinwaterofsomecoffee components showinghigh antioxidant activity (Del Castillo et al., 2002). Each coffee brewwas diluted (3:100 v/v) with demineralized water and an aliquot of 100  μ  L was added to 2 mL of radical cation ABTS solution (ABTS* + ).Afterexactly6minofdarkstorage,absorbancewasmeasuredat734nmusing a spectrophotometer UV-1601 (Shimadzu, Kyoto, Japan). The anti-oxidant capacity was expressed as micromoles of Trolox per mL coffeebrew ( μ  mol Trolox mL  − 1 ). The analyses were performed in triplicate foreach brewing procedure.  2.6. Caffeine quanti  󿬁 cation by HPLC  Quanti 󿬁 cation of caffeine was performed by HPLC in accordancewith the method reported by Niseteo et al. (2012) for coffee brews.The samples were  󿬁 ltered through a 0.45 μ  m  󿬁 lter (Nylon Membranes,Phenomenex, Torrance, CA, USA) and an HPLC Agilent Series 1100 wasused (Agilent Technologies, Palo Alto, CA, USA) with a PhotodiodeArray Detector with reversed-phase column Phenomenex C18 RP(250 × 4.6 mm, 4  μ  m i.d.) (Phenomenex, Torrance, CA, USA). The sol-vents consisted of 3% formic acid (solventA) and HPLCgrademethanol(solvent B) at a  󿬂 ow rate of 1 mL min − 1 . The elution was chosenaccording to that previously reported in literature (Niseteo et al.,2012). Chromatograms were recorded at 278 nm wavelength. Caffeineidenti 󿬁 cationandcalibrationwereperformedbycomparingtheretentiontime and spectral data obtained using the pure compound. ChemStationSoftware version A.09 (Agilent Technologies, Palo Alto, CA, USA) wasused for data acquisition and treatment. The analyses were performedin triplicate for each brewing procedure.  2.7. Analysis of volatile compounds by SPME-GC/MS  Volatile compounds were analyzed by solid-phase micro-extractiongas-chromatography coupled with mass spectrometry (SPME-GC/MS).A SPME device (Supelco Co., Bellefonte, USA) was equipped with a 󿬁 ber coated by divinylbenzene/carboxen/polydimethysiloxane (DVB/CAR/PDMS) 50/30  μ  m thickness 1 cm length coating phase. The sametype of   󿬁 ber was reported to be effective and highly ef  󿬁 cient for coffeearoma analysis (Akiyama et al., 2007; López-Galilea et al., 2006). The 󿬁 ber was conditioned at 250 °C for 3 h in a GC injection port prior tothe analysis in order to avoid the release of extraneous compounds.Within 2 min after coffee brewing, 10 mL coffee brew was put in a15 mL vial, immediately capped with a PTFE-silicon septum and thevial was put on a Trade Raypa magnetic stirrer (Analitica De Mori,Italia),andthe 󿬁 berwasinsertedinthesampleheadspaceforsamplingvolatile compounds at 50 °C for 2 min. The exposure timeand the con-dition for analysis were chosen according to Akiyama et al. (2007). AShimadzu GC – MS QP5050A (Kyoto, Japan) and a Supelcowax-10 fusedcapillary column 60 m × 0.32 mm i.d., 0.5  μ  m  󿬁 lm thickness (SupelcoCo., Bellefonte, USA) were used. To avoid contamination, a blank testwas performed before each analysis at the same chromatographic con-ditions of the sample analyses. The identi 󿬁 cation of compounds wascon 󿬁 rmed by using pure standards and comparison of their retentionindices and mass spectra. When reference compounds were not avail-able,atentativeidenti 󿬁 cationwasgivenonthebasisofthemassspectrastored in NIST libraries. GC – MS analysis in selective ion monitoring(SIM) was applied to quantify the volatile compounds. Indication of the employed ions and their peak areas normalized by the total areawas reported in Table 1. The results were indicated as a percentage of total peak area. Data were processed using the software Lab Solutions(GCMS Solution version 1.20, Shimadzu, Kyoto, Japan). The analysis of volatile compounds was performed in triplicate.  2.8. Statistical analysis Signi 󿬁 cant differences between coffee brewing techniques weredetermined for each coffee chemical component by one-wayANOVA. Tukey's test was used to discriminate among the means of the variables. Differences of   p  b  0.05 were considered signi 󿬁 cant.Principal component analysis (PCA) was performed on the antioxidantactivity(mmol TroloxL  − 1 ),caffeineconcentration(mgmL  − 1 ),totalphe-nolic compounds (mmol mL  − 1 ), total solids (mg mL  − 1 ), pH, and peakarea (%) for the volatile compounds to observe the main differencesamong different coffee brews. All chemical attributes were included inthe PCA, which was calculated based on the Pearson correlation matrix.Data elaboration was carried out using XLStat (version 2009.3.02), an 154  N. Caporaso et al. / Food Research International 61 (2014) 152 – 160  add-in software package for Microsoft Excel (Addinsoft Corp., Paris,France). 3. Results and discussion  3.1. pH, solids, total phenolic compounds, antioxidant activity and caffeine ThepHvaluesofArabicacoffeebrewsbydifferenttechniquesvariedfrom 5.52 (Neapolitan coffee) to 6.01 (American coffee), as reported inTable2A.BesidesNeapolitanandAmericancoffeebrewsarebothbasedon hot water percolation and long brewing time with respect to mokaand espresso, the results obtained about their acidity were quite unex-pected, and it could be probably explained by their total solid content.In fact, the total solid concentration, in which are considered the ali-phatic carboxylic acids mainly responsible of the coffee acidity (Clarke&Vitzthum,2001),signi 󿬁 cantlyvariedamongcoffeebrews.Inparticular,espresso coffee showed the highest extraction yield (73.66 mg mL  − 1 ),followed by moka and Neapolitan brews (56.47 mg mL  − 1 and48.97 mg mL  − 1 , respectively), that did not differ. The lowest valuewas obtained for American brew (12.20 mg mL  − 1 ). In general, thetotal solid concentration has been reported to in 󿬂 uence the sensoryproperty of coffee brew described as  “ body ”  (Gloess et al., 2013) andit seems to depend upon the coffee/water ratio (Andueza, Vila, Peña,& Cid, 2007) and the brewing procedure applied (López-Galileaet al., 2007). In fact, at higher amounts of ground coffee used, as itoccurs for the Neapolitan coffee brew, higher total solid contentwas measured. Moreover, higher temperature and pressure pro-mote higher extraction yields and rates, as occurred for espressoand moka with respect to  󿬁 ltered coffee brews. López-Galilea et al.(2007) reported higher concentration for total solids, and it was at-tributed to the higher pressure applied. Our results were in accor-dance with literature, in fact, a pressure of ~10 bar is generally theoutlet pressure in the espresso machine, followed by moka which uses apressure of about 1.5 bar and by the infusion methods (American andNeapolitan),inwhichwaterbrewsataboutatmosphericpressure.Thisef-fect could also partially explain the extraction ef  󿬁 ciency of the differentbrewing procedures (Table 2B). In fact, in the case of American brew, byconsidering the antioxidant activity on the dry basis (total coffee solids),itresultedinhigherlevelrespecttootherprocedures,whereasNeapolitancoffee resulted to be the lowest one (data not shown). The extraction ef- 󿬁 ciencycanbede 󿬁 nedastheratiobetweenthemassofthecoffeemate-rial that passes into the cup and the total ground coffee used (Clarke &Vitzthum, 2001). Nevertheless, the moka coffee brew gave rise to thehighest extraction of total solids (309.85 mg g − 1 ground coffee)followed by espresso (259.72 mg g − 1 ground coffee), Neapolitan(241.65 mg g − 1 ground coffee) and American coffee brew  Table 1 Chemical standards, odor descriptors and MS fragments used for quantitative analysis.Compound Odor descriptor a Ion fragments b (m/z)  Aldehydes Acetaldehyde Fruity I,II,VIII , pungent I,II,VIII , green VIII , ethereal VIII 43 2-Methylpropanal Malty I , banana IV,VIII , toasted III , fruity III,VIII , pungent III,VIII 41 – 72Butanal Chocolate V  , caramel V  , fruity VIII , green-fresh VIII 44 – 72 – 572-Methylbutanal Malty I,II,VIII , buttery III , oily III , fruity IV,V,VIII , roasted cocoa IV,VIII , chocolate-like V  , fermented VIII 57 – 443-Methylbutanal Malty I,II , buttery III , oily III , peach IV,VIII , chocolate IV,VIII , burned IV  , acrid-pungent VIII , fruity VIII 57 – 44Hexanal Green III, VI , grassy III, VII,VIII , fruity IV,VIII , leaf-like VI , fatty-green VII,VIII 56 Pyrazines 2-Ethyl-6-methylpyrazine Flowery V  , fruity V  , hazelnut-like VIII 121 – 1222-Ethyl-5-methylpyrazine Coffee-like VIII 121 – 1222-Propylpyrazine Green VIII , vegetable VIII 94 – 1222,6-Diethylpyrazine Pyrazine V  , potato-like V  , hazelnut-like VIII 135 – 1362-Ethyl-3,5-dimethylpyrazine Earthy I,V,VIII , roasty I,III,VIII , burnt III , meaty III , green III , nutty III , potato-like V  , almond IV  , nuts IV  135 – 1362-Methyl-3- trans -propenylpyrazine Roasty V  , green VIII , nitrobenzene-like VIII 119 – 134 Furans 2,5-Dimethylfuran Ethereal VIII 96 – 95 – 81Furfuryl methyl ether Herbal V  , potato-like V  , mustard VIII , nutty VIII , ricy VIII 81 – 112 – 53Furfurylmethyl sul 󿬁 de Sulfur IV  , garlic IV,VIII , toasty IV  81 – 1282-Furanmethanol acetate Ethereal- 󿬂 oral VIII , herbal-spicy VIII 81 – 98 – 1402-Furanmethanol Caramellic VIII , warm-oily VIII , burnt VIII , smoked VIII 98 – 97 Phenolic compounds Guaiacol Phenolic I,II,VIII , burnt I,II,VIII , smoky VI,VIII , spicy VII,VIII , harsh VII , earthy VII 109 – 81 – 1244-Ethylguaiacol Spicy I,II,III,VIII , phenolic II , smoky VIII , roasted VIII 137 – 152 – 1224-Vinylguaiacol Spicy I, II, III,VIII , phenolic II , eugenol-like III , clove-like VIII , smoky VIII , sweet VIII 150 – 135 – 107 Ketones 2,3-Pentanedione Buttery I,II,III,IV,V,VIII , oily III,IV,VIII , caramel-like V  43 – 57 β -Damascenone Honey-like I,II,VI,VIII , fruity I,II,V,VI,VII,VIII , sweet VII,VIII , woody VIII , tea-like VIII 69 – 190 – 105 Sulfur compounds Methanethiol Cabbage-like I,II,VIII , putrid II , sulphurous III , gasoline III , garlic III , rotten eggs III , meat III , cheesy III 47 – 48 Pyrroles 1-Methyl-(1H-pyrrol-2-yl)-1-ethanone Roselike V  , nutty VIII ,  󿬂 oreal VIII , smoky VIII 98 – 97 a The odor descriptors were indicated as reported in literature. I Grosch, 1998. II Semmelroch & Grosch, 1995. III D'Acampora Zellner, Dugo, Dugo, & Mondello, 2008. IV  do Nascimento, de Aquino, do Nascimento, Chang, & de Morais, 2007. V  López-Galilea et al., 2006. VI Mayer & Grosch, 2001. VII Piccone, Lonzarich, Navarini, Fusella, & Pittia, 2012. VIII Flament, 2002. b Bold numbers indicate quanti 󿬁 er ions.155 N. Caporaso et al. / Food Research International 61 (2014) 152 – 160  (112.27 mg g − 1 ground coffee). This result could be explained as aneffect of both the water pressure and temperature, but also attribut-ed to the brewing time, because longer brewing time implies longercontact time between the coffee and water, thus allowing a higherextraction of some compounds (Gloess et al., 2013). The sametrend was obtained for total polyphenols and caffeine concentra-tions (Table 2A). The concentration of total phenolic compounds re-sulted higher in espresso technique, while moka and Neapolitanshowed a lower extraction. The lower level of total phenolic com-pounds resulted for American coffee, which gave rise to less thanhalf the value obtained from other brewing techniques. This resultwas not in accordance with previously published papers (Gloesset al., 2013; Pérez-Martínez et al., 2010), but this difference couldbe due to different water/ground coffee ratios and the  󿬁 nal volumeobtained. Concerning the extraction ef  󿬁 ciency, Neapolitan coffeebrew showed the highest level of total phenolic compounds with re-spect to all other techniques considered (Table 2B). This result wasexplained by the higher contact time during brewing process, inpartial agreement with previous papers (Ludwig et al., 2012). TheAmerican technique resulted to be the less ef  󿬁 cient among thefour studied brewing methods.Thecaffeineconcentrationinthebrewingtechniquesanalyzedrangedfrom1.30mgmL  − 1 (Neapolitan)to2.44mgmL  − 1 (espresso).Nosignif-icant differences were obtained among Neapolitan (1.30 mg mL  − 1 ),American (1.39 mg mL  − 1 ) and moka (1.68 mg mL  − 1 ) coffee brews.These  󿬁 ndings were similar to those reported by Santini et al. (2011) fordifferent coffee beverages. The higher caffeine concentration in espressocoffee brew could be explained by the very low volume (25 mL) andthe higher pressure in espresso with respect to other extraction tech-niques (Santini et al., 2011).DespitethelowcaffeineconcentrationinAmericancoffeebrew,thisbrewing procedure allowed the highest caffeine extraction ef  󿬁 ciency(12.75 mg g − 1 ground coffee), considering the amount of caffeine ex-tracted with respect to the coffee powder used. The caffeine yield forAmerican brew was almost double with respect to the Neapolitanbrew,besides thesimilarities ofthesetwotechniques inthetypeofex-traction. This difference could be explained by the higher temperatureof American coffee also after brewing procedure because of the coffeemachine hotplate, while Neapolitan coffee pot is rapidly cooled imme-diately before the percolation process. Considering that caffeine ishydrosoluble, the highest caffeine extraction ef  󿬁 ciency for Americanbrew could be related to the time of brew preparation, or due to thetime of contact between coffee and hot plate.Somecoffeecompoundssuchascaffeineorphenolicsaschlorogenicacids,hydroxycinnamicacidsorcompoundsproducedfromMaillardre-action (MR) such as melanoidins have been identi 󿬁 ed as antioxidantsand have bene 󿬁 t effects. Antioxidant activity evaluated by the ABTS + method resulted signi 󿬁 cantlydifferentamongdifferentbrewingproce-dures.Thelowerantioxidantactivitywasobtained for Americancoffee,whileNeapolitancoffeeresultedinadoublevalueforantioxidantactiv-ity with respect to the  󿬁 rst one. Antioxidant activity for moka andespresso was more than three times higher with respect to theAmerican brew, as showed in Table 2A. This result was partially attrib-uted to the dilution effect of the brewing techniques, whereas one hasto consider that we did not perform a complete characterization of allthe coffee components which could have in 󿬂 uenced its antioxidant ac-tivity. Generally, the results for antioxidant activity re 󿬂 ected those ob-tained for total phenolic compounds, except for moka coffee. In fact, alower amount of phenolic compounds wasfound in moka with respectto espresso coffee brew and the level was similar to Neapolitan coffeebrew. This result was explained by the probably higher formation of MRP due to higher extraction temperatures and time in moka pot(Sacchettietal.,2009).Infact,asitiswellknown,theABTS + radicalre-acts with any hydroxylated aromatic compound, based on electron-transfer redox reaction, and for this reason one cannot distinguish anantioxidant activity due to phenolic and non-phenolic compoundssuch as MRPs. The quanti 󿬁 cation of the melanoidins in the coffeebrews would be necessary to fully explain the changes in antioxidantactivity of coffee brews. Therefore, Neapolitan coffee brew showed anintermediate antioxidant activity, although the total polyphenol con-tent was similar to that of moka brew. It is important to highlight thatthe roasting process has a crucial effect on the antioxidant activity of coffee brews, and increases up to 25% of the antioxidant activity wasreportedrelatedtotheformationofnewproductsfromMaillard'sreac-tion, particularly melanoidins (Napolitano et al., 2007). Pérez-Martínez et al. (2010) reported that, besides the melanoidin compounds, higherantioxidant activity in moka coffee was due to the chlorogenic acids,i.e. caffeoylquinic acid isomers. Moreover, Vignoli et al. (2013) found acorrelation between caffeine concentration and antioxidant activity,both in Robusta and Arabica coffee. The same authors gave a wide dis-cussiononthepossiblefactorsaffectingtheconcentrationofcoffeebio-active compounds and antioxidant activity. Thus, our results could beexplainedbythedifferentoperativeconditionssuchasthe 󿬂 ameinten-sity applied to the moka pot. In fact, higher temperatures in the mokapot (as it is in contact with the  󿬂 ame until all the water passes in theupper part) could break the covalent bond between chlorogenic acids  Table 2 pH, temperature, total solids, total phenolics evaluated by Folin – Ciocalteu method, antioxidant activity evaluated by ABTS, and caffeine content of different coffee brews (A). Coffeeextraction, considering the brewed coffee obtained with respect to the amount of ground coffee used (see Section 2.2) (B). Values expressed  “ per cup ”  were calculated considering onecoffee cup equal to a volume of 125 mL (American coffee), 40 mL (Moka and Neapolitan coffee) and 25 mL (Espresso) (C).American Neapolitan Moka Espresso(  A )  Concentration pH (20 ± 1 °C) 6.01 ± 0.09 a 5.52 ± 0.12 c 5.71 ± 0.15 bc 5.87 ± 0.02 abT (°C) 66.40 ± 0.65 bc 61.00 ± 1.50 c 80.23 ± 3.75 a 68.00 ± 1.50 bTotal solids (mg mL  − 1 ) 12.20 ± 0.91 c 48.97 ± 4.01 b 56.47 ± 7.05 b 73.66 ± 8.90 aTotal phenolics (mmol mL  − 1 gallic acid) 14.08 ± 0.58 c 36.56 ± 1.55 b 35.43 ± 2.55 b 46.35 ± 3.81 aCaffeine (mg mL  − 1 ) 1.39 ± 0.30 b 1.30 ± 0.18 b 1.68 ± 0.20 b 2.44 ± 0.24 aABTS (mmol L  − 1 Trolox) 22.88 ± 1.06 c 47.94 ± 13.79 b 71.89 ± 6.10 a 81.50 ± 5.74 a( B )  Extraction ef   󿬁 ciency Total solids (mg g − 1 ground coffee) 112.27 ± 8.35 c 241.65 ± 19.80 b 309.85 ± 38.69 a 259.72 ± 31.40 bTotal phenolics (mg gallic acid g − 1 ground coffee) 22.03 ± 0.91 c 34.13 ± 1.45 a 29.74 ± 2.14 b 27.81 ± 2.28 bCaffeine (mg g − 1 ground coffee) 12.75 ± 2.73 a 6.33 ± 0.88 b 9.22 ± 1.10 ab 8.60 ± 0.84 abABTS (mmol Trolox g − 1 ground coffee) 0.21 ± 0.01 c 0.24 ± 0.07 c 0.39 ± 0.03 a 0.29 ± 0.02 b( C  )  Intake per cup Total solids (mg) 1525.36 ± 113.41 c 1958.67 ± 160.51 b 2258.89 ± 282.05 a 1841.42 ± 222.62 bTotal phenolics (mg gallic acid) 299.38 ± 12.36 a 248.78 ± 7.91 b 241.09 ± 17.35 b 197.14 ± 16.20 cCaffeine (mg) 173.25 ± 37.13 a 52.00 ± 7.25 b 67.18 ± 8.00 b 60.95 ± 5.94 bABTS (mmol Trolox) 2.86 ± 0.13 a 1.92 ± 0.55 b 2.87 ± 0.24 a 2.04 ± 0.14 bAll values are shown as means ± standard deviation (n = 9). Numbers followed by different letters on the same line are signi 󿬁 cantly different (  p  b  0.05).156  N. Caporaso et al. / Food Research International 61 (2014) 152 – 160
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