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1 Food Chemistry () 6 Contents lists ville t SieneDiret Food Chemistry journl homepge: Effet of proessing on the qulity of edile rgn oil Bertrnd Mtthäus, *, Dominique Guillume, Sïd Ghry,d, Aziz Hddd, Hihm Hrhr d, Zouid Chrrouf d Mx Runer-Institute, Federl Reserh Institute for Nutrition nd Food, Piusllee 68/76, D-87 Münster, Germny Institut de Chimie Moléulire de Reims, UMR 69, Rue Cognq Jy, Reims, Frne Lortoire Contrôle Qulité, Lesieur, Cristl,, Rue Cporl Cori, Rohes Noires, Csln, Moroo d Lortoire de Chimie des Plntes et de Synthèse Orgnique et Bioorgnique, Fulté des Sienes, Université Mohmmed V-Agdl, BP, Rt, Moroo rtile info strt Artile history: Reeived Mrh 9 Reeived in revised form 7 Otoer 9 Aepted 8 Otoer 9 Keywords: Argn oil Orgnolepti qulity Sensory qulity Lipid oxidtion Moroo Sensory qulity of edile oil is essentil to get the onsumer eptne. Modifitions during proessing n lter edile oil sensory qulity. The storge stility nd sensory qulity of rgn oil prepred from () mehnilly pressed unrosted kernels, () mehnilly pressed rosted kernels, () hnd-pressed rosted kernels, nd () hnd-pressed rosted kernels oming from got-digested fruits ws studied t room temperture nd under elerted onditions (6 C). The rosting proess hd positive effet on storge stility of the resulting oils, while rgn oil prepred from mehnilly pressed rosted kernels provides the optimum storge stility. Oil from hnd-pressed rosted kernels originting from got-digested fruits ws not suitle for humn onsumption euse of the unplesnt tste nd odoûr. Only oil from mehnilly pressed rosted kernels did not produe negtive sensory ttriutes like fusty or Roquefort heese. Ó 9 Elsevier Ltd. All rights reserved.. Introdution * Corresponding uthor. Tel.: +9 () 867 ; fx: +9 () E-mil ddress: ertrnd.mtthus@mri.und.de (B. Mtthäus). Argn tree (Argni spinos) is only endemi in Southwestern Moroo where the rgn forest ws reognised s iosphere reserve y the UNESCO in 998. The rgn forest is urrently overing slightly more thn 8, h, ut its extension ws twie s lrge t the end of the nineteenth entury (Morton & Voss, 987). To void further deteriortion nd fvour its sustinle development, n inrese of its eonomi vlue is n solute neessity. Argn oil hs rpidly emerged s the only produe le to ring more welth to the Berer popultion (Chrrouf, Hrhr, Ghry, & Guillume, 8), the trditionl rgn forest dwellers, euse of its unique dietry nd physiologil properties (Chrrouf & Guillume, 999; Chrrouf & Guillume, 8). Thus, prospets for etter eonomi return hve enourged dwellers to modernise rgn oil prodution methods for the export mrket. For yers, rgn oil hs een prepred exlusively y Berer women following n nestrl multistep proess (Chrrouf, Guillume, & Driouih, ). Between My nd August, fllen ripe fruit re olleted through the rgn forest. Then, the fruits re sun-dried for few dys nd their dried peel is mnully removed, resulting in rgn nuts. An verge of kg of dried-fruits nd h (single person) is neessry to otin 6 kg of rgn nuts. Argn nuts re then roken etween two stones nd the white kernels re olleted. From 6 kg of rgn nuts, only 6. kg of kernels re olleted. To prepre edile rgn oil, kernels hve to e rosted for few minutes ut overheting should e voided sine it negtively influenes the finl oil tste. The rosted kernels re susequently rushed using millstone resulting in rownish visous liquid tht is mixed with wter. This dough is hnd-mlxed for severl minutes, slowly getting solid nd relesing n emulsion from whih rgn oil is finlly dented. Unfortuntely, this method is very slow (for single person 8 h of work re neessry to get. L of oil), leding to oil thes hving vrile orgnolepti properties due to non-reproduile rosting (Chrrouf, El Hmhi, Mlli, Liitr, & Guillume, 6) nd hemil omposition of oil thes (Hilli, Chrrouf, El Aziz Soulhi, Hhimi, & Guillume, ), nd finlly frequently rising teriologil onerns. Reently the preprtion proess of rgn oil hs een modified nd high-qulity rgn oil n now e produed on lrge sle (Chrrouf et l., ). Sine edile rgn oil is not refined, rw mteril qulity nd oil proessing diretly impt on its qulity (Cyuel et l., 8; Mrfil et l., 8). Sensory qulity of vegetle oil n lso deteriorte during storge. Chnges ourring during fruit or seed storge (Gutierrez, Vron, & Ali, ; Klu, Bedgood, Bishop, & Prenzler, 8; Mtthäus & Brühl, 8), n lso led to oxidtive retions one the oil hs een ottled. In this ltter se, toopherols (vitmin-e-tive ompounds) nd sterols hve een shown to e importnt ftors involved in the sensory qulity of olive oil 8-86/$ - see front mtter Ó 9 Elsevier Ltd. All rights reserved. doi:.6/j.foodhem.9..

2 B. Mtthäus et l. / Food Chemistry () 6 7 (Gutierrez & Fernndez, ; Rsrelli, Pssi, Ippolito, V, & De Simone, ). Up to now, very little is known out the influene of eh proessing step on the qulity of rgn oil during storge even though the involvement of toopherols nd sterols on oil qulity hs een suggested (Verhé, 9). Therefore, we evluted the onentrtion of these two types of ompounds in rgn oil s funtion of storge time; the ultimte im of the present study eing to determine the effets of the prodution onditions on the sensory qulity nd storge stility of edile rgn oil. Storge ws t C for up to weeks to relte to rel storge onditions nd t 6 C for up to dys to elerte the storge ondition.. Mteril nd methods.. Prodution of rgn oil Peeled rgn fruits ( kg) were olleted in Tiout (Provine of Troudnt, Moroo) in 7. Fruits were sun-dried for two weeks nd then mehnilly dehulled (SMIR Tehnotour, Agdir, Moroo). Argn nuts were mnully opened using the trditionl twostone method (Chrrouf et l., ) to get the kernels. A frtion of the nuts ws rosted t C for min (roster: SMIR, Tehnotour Agdir, Moroo). Afterwrds oil extrtion ws rried out s done trditionlly or mehnilly using Komet DD 8 G press (IBG Monforts Oekote GmH & Co. KG, Mönhengldh, Germny). Got-digested rgn fruits ( kg) were treted s peeled olleted fruits ut rgn oil ws trditionlly extrted. Therefore, four types of rgn oil were nlysed: () rgn oil from unrosted kernels, mehnilly extrted; () rgn oil from rosted kernels, mehnilly extrted; () rgn oil from rosted kernels, trditionlly extrted; nd () rgn oil from got-digested seeds, rosted nd trditionlly extrted. For eh oil type,. L of oil were prepred nd kept in ml rown glss ottles, resulting in the prodution of eleven ottles for eh oil smple... Storge of the oils One ottle ws used to evlute the initil stte of the oils with regrd to the sensory qulity nd the oxidtive stte. Five ottles of given oil type were stored t C± C for weeks nd the five remining ottles were stored t 6 C± C for dys. From the ottles stored t C, one ottle ws used for sensory nlysis nd investigtion of its hemil prmeters every four weeks. For the ottles stored t 6 C, one ottle ws used for investigtion of its hemil prmeters every seven dys... Sensory evlution The sensory evlution of the oil smples stored t C ws rried out ording to the DGF method C-II (7) (DGF, 8) with pnel of four trined tsters. In order to pereive the rom of the rgn oils the oils were tsted in speil lue oloured glsses typil for the sensory evlution of olive oils. They were overed with wth glss to gther/keep the voltile rom ompounds for the time of the sensory ssessment session. Every glss ws filled with the sme mount of out ml of oil to ensure tht the oil develops n intense hedspe rom nd the voltile ompounds diffuse in the overed glss. The oils were evluted t room temperture. The flvour nd tste of the oils were hrterised ording to sensory desription form, previously developed y the sensory pnel over period of yers nd ssessment of nerly different rgn oils from different lotions, prodution filities, nd types of proess. A soring system with sle from (not detetle) to (strongly detetle) ws used to hrterise the typil (nutty, rosty) nd typil (Roquefort heese, rnid, wood-like, itter, urnt, musty, yest-like, fusty, nd others) ttriutes. The dt sets otined from the sensory ssessments were sttistilly evluted in order to improve the reliility nd repetility of the results. Sine the men of the results for one ttriute is influened y every single result, espeilly y outliers, in the dt set the medin hs een lulted s the est result. In ddition the reltive oeffiients of vrition of the results were lulted in order to get rough estimtion whether the finl result is n unnimous result or heterogeneous one. The reltive oeffiient of vrition for the different ttriutes hs to e elow %... Peroxide nd nisidine vlues The peroxide nd nisidine vlue were determined following the DGF method C-VI 6 nd DGF method C-VI 6e, respetively (DGF, 8)... Vitmin-E-tive ompounds For the determintion of vitmin-e-tive ompounds solution of mg oil in ml n-heptne ws used for HPLC nlysis. The nlysis ws onduted using Merk Hithi low pressure grdient system, fitted with L-6 pump, Merk Hithi F- Fluoresene Spetrophotometer (detetor wvelengths for exittion 9 nm, for emission nm) nd D- integrtion system. The smple ( ll) ws injeted y Merk 6-A utosmpler onto Diol phse HPLC olumn m.6 mm ID (Merk, Drmstdt, Germny) used with flow rte of. ml/ min nd heptne/tert-utyl methyl ether (99:, v/v) s moile phse (Blz, Shulte, & Thier, 99; DGF, 8). Results re given s mg vitmin-e-tive ompounds/kg oil..6. Sterol omposition Sterol omposition ws evluted y GLC-FID/pillry olumn. Briefly, sterols purified from the unsponifile mtters y HPLC were trnsformed into their trimethylsilyl ethers ounterprts using pyridine, hexmethyldisilzne, nd trimethylhlorosilne 9:: (v/v/v). The sterol profile ws nlysed using gs-phse hromtogrph fitted with hrom pk CP SIL 8 C B olumn ( m. mm i.d.) nd flme ionistion detetor. The temperture of the injetor nd detetor were oth C. The olumn temperture ws C nd progrmmed to inrese t the rte of C/min to 7 C. The rrier gs ws dry oxygen-free nitrogen, nd the internl pressure ws 8.6 r. Sterol quntifition ws hieved y use of n internl.% hloroform solution of - holestnol..7. Content of hexnl Hexnl ws determined y the method of dynmi hedspe onentrtion (Brühl & Fieig, ): Aout mg of oil were weighed extly into ml hedspe vil, seled nd put into PTA (Axel Semru, Sprokhövel, Germny) utosmpler. Voltiles were purged with nitrogen t PSI with strem of ml/min over the smple surfe t 8 C nd trpped in n on-line Tenx trp (eight fold volume) t 6 C using ron dioxide ooling. After min of trpping, ll voltiles were removed y heting the trp to C for min. The purge vlve ws held t C nd the trnsfer line (unoted fused sili) t C in order to void reondenstion without ny wter trp in the system.

3 8 B. Mtthäus et l. / Food Chemistry () 6 The heting jket of the trnsfer line ws onneted to split/ splitless injetor of HP89 GC insted of the septum p nd the trnsfer line ws led through the injetor diretly into the oven where it ws onneted to gurd olumn m Crowx,. mm ID. lm film thikness nd seprting olumn CP- Sil 9 (% ynopropyl-phenyl + 86% dimethylpolysiloxne, 6 m,. mm ID, lm FD; The olumn ws onneted to flme ionistion detetor t 8 C. The oven temperture ws held for min. t C, with no dditionl old trp fousing neessry, C/min to C, min isotherm..8. Sttistil nlysis Student s t-test to evlute the sttistil signifine for independent nd vriles intertions ws performed with two-tiled t-tests t P =.. The dt ws evluted using omputer progrm (Sttgrphis, Rokville, MD, USA).. Results.. Sensory evlution An essentil prmeter for the evlution of edile oils is its sensory qulity. Aville stndrds on edile oils, suh s Codex Alimentrius Stndrd for Nmed Vegetle Oils (Codex Alimentrius, 99) or Germn Guidelines for edile fts nd oils (Leitsätze, 997), define the sensory evlution s the predominnt prmeter for ssessing qulity of edile oils. Depending on their initil preprtion proess, eh rgn oil smple hd different tste nd smell t the eginning of the storge experiment (Fig. ). While oil smples from unrosted seeds hd nutty tste, oil smples from rosted seeds were hrterised y the pperne of nutty nd rosty ttriutes. In oil from got-digested seeds slight fusty ttriute ws lso pereivle. During storge the sensory senstions of oil from unrosted seeds hnged very fst nd within weeks ttriutes like fusty s well s Roquefort heese ppered resulting in oil judged s inedile for humns euse of their uneptle tste. A similr judgement ws expressed for rgn oil otined from rosted seeds y trditionl extrtion. Just fter extrtion, the typil nutty nd rosty ttriutes hrterising fresh rgn oil were found with no ttriute negtively ffeting the oil qulity. However, during storge the nutty ttriute disppered within 6 weeks of storge nd Roquefort heese tste developed. The rosty ttriute ws still pereivle fter weeks of storge, ut due to Roquefort heese tste the oil ws onsidered inedile fter weeks of storge. No hnge of the sensory hrteristis ws found for rosted kernel oils otined y mehnil extrtion. Over week storge period t C only the typil sensory ttriutes nutty nd rosty were pereivle. Only slight derese in the intensity of these ttriutes ws noted t the end of the experiment. Oils from got-digested seeds ehved differently. Fresh oil otined from got-digested fruit ws hrterised y typil smell nd tste for Roquefort heese whose intensity inresed with the storge time. Sine tsters identified the ttriute Roquefort heese only in oil smples prepred either with improper rw mteril (got-digested seeds) or whose qulity hd deresed during storge, this ttriute is ler indition for improper rgn oil qulity... Hexnl Hexnl ontent is key omponent to evlute the oxidtive deteriortion of linolei id-ontining oils. Sine hexnl Intensity ( = not detetle; = strongly detetle) unrosted, meh. extrted rosted, meh. Extrted rosted, trd. extrted rosted, gots, trd. Extrted nutty 8 6 Storge time [weeks] Intensity ( = not detetle; = strongly detetle) unrosted, meh. extrted rosted, meh. Extrted rosted, trd. extrted rosted, gots, trd. Extrted rosty 8 6 Storge time [weeks] Intensity ( = not detetle; = strongly detetle) unrosted, meh. extrted rosted, meh. Extrted rosted, trd. extrted rosted, gots, trd. Extrted fusty 8 6 Storge time [weeks] Intensity ( = not detetle; = strongly detetle) unrosted, meh. extrted rosted, meh. Extrted rosted, trd. extrted rosted, gots, trd. Extrted 8 6 Storge time [weeks] Roquefort Fig.. Sensory evlution of rgn oil during storge t C.

4 B. Mtthäus et l. / Food Chemistry () 6 9 onentrtion of. mg/kg of oil n result in the pereption of the ttriute rnid y trined pnel (unpulished result), hexnl level is onsequently of the upmost importne for the sensory desription of rgn oils. Fig. shows the influene of storge time nd proess on the formtion of hexnl. At the eginning of the storge experiment, rgn oil prepred from mehnilly extrted rosted seeds displyed the highest hexnl level (. mg/kg) likely due the rosting proess nd/or the het resulting from mehnil extrtion. After dys of storge t 6 C, the hexnl ontent in this ltter oil inresed only slightly to reh.6 mg/kg. The lrgest inrese (from. to.7 mg/kg) ws found for rgn oil prepred from unrosted rgn seeds. For the other oils, fter dys, the hexnl onentrtion ws found to e ove the. mg/kg threshold vlue, oil from unrosted seeds rehing this vlue fter only 8 dys. Storge t C remrkly redued the rte of formtion of hexnl. After weeks of storge only very smll inrese of hexnl level ws found in ll oils, from.. to. mg/kg... Oxidtive stte Lipid oxidtion hs een identified s the min ftor responsile for deteriortion of edile oil qulity nd oxidised lipids n further elerte the deteriortion of sensory qulity in oil nd derese the onsumer eptne (Josen, 999). For ommerilistion of edile oils, the shelf life of the produts is essentil to sertin period of time suffiient to ridge the time gp seprting the prodution nd the onsumer, within the given legisltive regultions for the oxidtive stte. Severl prmeters desrie the oxidtive stte of edile oils. One is the peroxide vlue whih inreses with progressive oxidtion of the oil until the rte of degrdtion of the formed hydroperoxides exeeds the formtion of new hydroperoxides. In ontrst to the peroxide vlue, the nisidine vlue mesures seondry deomposition produts suh s ronyl ompounds (ldehydes nd ketones) ffeting negtively the tste nd smell of edile oils. Peroxide vlue strongly depends on the extrtion method, seed tretment, nd geogrphil origin (Cyuel et l., 8; Mrfil et l., 8). Trditionlly extrted oils from rosted nd unrosted seeds showed.-fold higher peroxide vlue thn the semi-utomtilly prepred ones (Cyuel et l., 8). Higher men peroxide vlues for oil otined y the semi-utomti method in omprison with the trditionl method hve een reported (Mrfil et l., 8), ut smples prepred y the trditionl method showed wider peroxide vlue rnge. Content of hexnl [mg/kg] h i Storge time t 6 C [dys] 7 8 f f f e e,d d unrosted, rosted, rosted, meh. extrted meh. extrted trd. extrted h e g rosted, gots, trd. extrted Fig.. Development of hexnl during storge of rgn oils from different proessing t 6 C (rs with different supersripts re signifintly (P 6.) different). Our study reveled tht prodution onditions influene the oxidtive stility of rgn oil, espeilly t high storge tempertures. Indeed, storge t C resulted in notiele inrese of the peroxide vlue for the different smples, ut none of them rehed the limits of or meq O /kg of oil given y different stndrds (Codex Alimentrius, 99; Leitsätze, 997) within the storge time of weeks (results not shown). Interestingly, the rosting proess seems to improve the oxidtive stility of rgn oil; oil from unrosted seeds showing signifintly fster inrese (P 6.) of its peroxide vlue during storge thn oils from rosted seeds (Fig. ). At storge temperture of 6 C, the effet of rosting on the peroxide vlue ws more pronouned. Indeed, the peroxide vlue of rgn oil from unrosted seeds inresed up to meq O /kg wheres tht for other oils ws signifintly lower (P 6.). Nevertheless, oil from trditionlly extrted rosted kernels nd trditionlly extrted got-digested seeds rehed the limit of meq O /kg within 8 dys of storge t 6 C. Only the mehnilly extrted oil from rosted kernels remined elow the limit during ll the storge experiment. The inrese in seondry oxidtion produts ws only very smll during storge t 6 C nd, fter dys, the oil smples only rehed nisidine vlues etween.8 nd.. After weeks of storge t C, the nisidine vlues rnged etween. nd.7 (results not presented)... Vitmin-E-tive ompounds The mount of vitmin-e-tive ompounds in mehnilly extrted rgn oil generlly rnges etween nd 77 mg/kg (Hilli et l., ) nd onsisted of out 8% of -toopherol (Chrrouf & Guillume, 7). The highest initil mount -toopherol, -toopherol, nd d- toopherol in the oil prepred from mehnilly extrted rosted seeds ws 6.6,., nd 7. mg/kg, respetively, even though this ontent did not signifintly differ from orresponding vlues in oils from unrosted seeds or rosted seeds fter trditionl proessing (Tle ). Conversely, the totl mount of vitmin-e-tive ompounds in oil from got-digested seeds ws signifint lower (-toopherol, -toopherol, nd d-toopherol:.6, 8.7, nd. mg/kg, respetively). Storge t C did not signifintly derese the mount of vitmin-e-tive ompounds in the different oils. After weeks of storge, the oils ontined pproximtely the sme onentrtion of vitmin-e-tive ompounds s t the initil time (results not shown). Under elerted storge onditions, more ontrsted results were oserved (Tle ). Quntittively, the most drmti derese in vitmin-e-tive Peroxide vlue [meqo /kg] f h,i unrosted, meh. extrted j k Storge time t 6 C [dys] 7 8 d e,f e rosted, meh. extrted e g h rosted, trd. extrted,d rosted, gots, trd. extrted Fig.. Peroxide vlue of rgn oil during storge t nd 6 C (rs with different supersripts re signifintly (P 6.) different). f g i

5 Tle -, -, nd d-toopherol levels (mg/kg) in rgn oil during storge t 6 C (deiml hve een omitted for ese of presenttion). Storge time (dys) Unrosted, mehnil extrtion Rosted, mehnil extrtion Rosted, trditionl extrtion Rosted, gots, trditionl extrtion d d d d 6 ±.6 8 ± 8. ±. f 6 ±.6 ±. 8 ±.8 h ±. ±. ±. h ±. h 8 ± 8. e ±. f 7 6 ±.6 7 ± 7. 9 ±.9 f ±. 78 ± 7.8 ±. f ±. ±. ±. f 7 ±.7 fh 7 ± 7. e 8 ±.8 f ±. 7 ± 7. ±. ±. 6 ± 6. ±. ±. ±. ±. f 8 ±.8 fh 6 ± 6. e 9 ±.9 f ±. ±. ±. ±. 6 ± 6. 8 ±.8 g ±. ±. e 8 ±.8 f ±. f 99 ± 9.9 e ±. f 8 ±. ±. ±. ±. 6 ± 6. 8 ±.8 f ±. 6 ±.6 ie 7 ±.7 ±. f 6 ± 6. e 6 ±.6 9 ±.9 ±. d ±. ±. 88 ± 8.8 e ±. ±. 9 ±.9 d ±. ±. f 6 ±.6 de 8 ±.8 f Vlues ering different supersripts re signifintly (P 6.) different. Tle Sterol levels (mg/ g of oil) during storge t 6 (deiml hve een omitted for ese of presenttion). B. Mtthäus et l. / Food Chemistry () 6 Storge time (dys) Unrosted, mehnil extrtion Rosted, mehnil extrtion Rosted, trditionl extrtion Rosted, gots, trditionl extrtion St8 * Sp * S * St7 St8 * Sp * S * St7 St8 * Sp * S * St7 * St8 * Sp * S * St7 * ±. 9 ±. d ±. df 6 ±. h ±. 6 ±.8 d 7 ±. e 6 ±. h ±. 8 ±.9 d 6 ±. e ±. ±. ±. d ±. de ±. 7 ±. ±. d ±. df ±. ±. 6 ±.8 d ±. df ±. ±. ±.6 i ±. d ±. ±. ±. i 8 ±. e ±. ±. ±. d 9 ±.e ±. ±. 6 ±. e ±. e ±. ±. ±. d ±. de ±. ±. 7 ±.9 d 8 ±. e ±. ±. ±. d ±.6 eg 6 ±. h ±. 8 ±. e 9 ±.e ±. ±. 9 ±. d ±. d 6 ±. h ±. 9 ±.9 d 9 ±. e ±. 8 ±. ±. e 7 ±. e ±. ±. ±. de ±.7 eg ±. ±. ±. d ±. e 6 ±. h ±. 7 ±.9 d 8 ±. e ±. ±. 9 ±. d ±. e ±. ±. ±. d ±.6 e ±. 6 ±. h 9 ±. d 6 ±. e 6 ±. h ±. 9 ±. d ±. d ±. Vlues ering different supersripts re signifintly (P 6.) different. * St8, stigmst-8,-dien--ol; SP, spinsteroll S, shottenol; nd St7, stigmst-7,-dien--ol.

6 B. Mtthäus et l. / Food Chemistry () 6 ompounds ws found for the oil from unrosted seeds for whih, fter dys of storge t 6 C, the onentrtion in vitmin-e-tive ompounds ws nerly %. Qulittively, ll three types of toopherols were ffeted y the oxidtive proess, ut their reltive distriution remined lmost unhnged: -toopherol, - toopherol, nd d-toopherol:.%, 88.%, nd.8%, respetively. Oils from rosted seeds (mehnil nd trditionl extrtion) lso showed signifint derese in vitmin-e-tive ompounds fter dys of storge t 6 C, even though it ws not s strong s for the oil from unrosted seeds. The toopherol level in oil from seeds oming from got digestion, tht ws lredy initilly lower thn in the other oils, showed lso signifint derese, ut in omprison to the other oils, the effet ws notly redued... Sterol omposition Argn oil sterol frtion ontins five ompounds (Hilli et l., ), minly stigmst-8,-dien--ol (St8), spinsterol (Sp), shottenol (S), nd stigmst-7,-dien--ol (St7). Cmpesterol is lso found ut t low onentrtion lose to.%. Therefore, we deided to quntify the four min sterols during our study. Surprisingly, the initil sterol ontent in rgn oil from got-digested seeds ws muh higher thn tht in the three other oil smples (97. mg/ g of oil vs.. ± 8. mg/ g of oil). Nevertheless, the sterol frtion omposition remined qulittively nd quntittively onstnt during storge evlution nd no signifint vritions were oserved over week storge period t C or dys under elerted storge onditions (Tle ). These results suggest tht the sterol frtion is neither tively involved in the preservtion of rgn oil nor in its tste. Also, the ft tht sterol frtion omposition is unffeted during the storge period is n importnt ftor onsidering the phrmologil properties ttriuted to this lss of ompounds (Trutwein & Demonty, 7).. Disussion Tretment of the rgn kernels nd proessing hs signifint (P 6.) influene on the sensory qulity nd oxidtive stte of rgn oil. Although differenes in the oxidtive stte or stility mongst different oil smples re more pronouned t 6 C thn t room temperture, our results show tht oils from rosted kernels were signifintly less suseptile to oxidtion during storge s shown y the evlution of peroxide vlue nd the formtion of hexnl s one key ompound of oxidtive deteriortion. The high stility of rgn oil towrd oxidtion n e in prt explined y its high toopherol ontent. Phenoli ompounds re well known to provide high resistne to utoxidtion nd sine our study does not lerly indite the involvement of speifi toopherol in this proess, it is likely to result from the synergisti tion of -, -, nd d-toopherols, possily together with other minor phenoli ompounds (Shhidi & Wnsundr, 99). The etter stility of rgn oil prepred from rosted seeds ould e explined y etter extrtility of ntioxidtive ompounds from the kernels or the formtion of suh ompounds suh s Millrd retion produts (MRP) during the rosting step. During rosting, tempertures ove C re used, resulting likely in remrkle hnges in the struture of the seed mteril with disruption of oil-ering ells. Suh tempertures re lso suffiient for the formtion of MPRs. Severl of these ompounds re desried with high ntioxidtive effet (Eihner, 98; Lingnert & Eriksson, 98). Although the differenes mongst oil smples stored t C were minor, with regrd to prmeters desriing the oxidtive ehviour of the oils, mjor differenes were reveled y the sensory evlution. Aording to food offiil stndrds, oil smples from got-digested seeds were not suitle for humn onsumption euse of strong pereption of ttriutes like fusty nd Roquefort heese even t the eginning of the storge experiment. In oil from unrosted seeds the development of the unplesnt fusty nd Roquefort heese ttriutes ws quik, overing the pereption of the nutty ttriute tht ws only slightly pereivle t the eginning of the experiment. In trditionlly extrted oils from rosted kernels, negtive ttriutes were reported fter weeks of storge t C. Despite strong rosty rom the development of the fusty nd Roquefort heese ttriutes eme pereivle, while in oil from mehnilly extrted rosted seeds, no negtive orgnolepti ttriutes were deteted even fter weeks of storge. The reson for this differene etween the two types of rosted oils my originte from the existing differenes in different extrtion methods of the oil. Use of wter in omintion with hndwork, result likely in worse initil onditions for the oxidtive stility of the oil (Hilli et l., ). Referenes Blz, M., Shulte, E., & Thier, H. P. (99). Trennung von Toopherolen und Tootrienolen durh HPLC. Ft Siene Tehnology, 9, 9. Brühl, B., & Fieig, H.-J. (). Assistne of dynmi hedspe hromtogrphy for pnel sensory evlution. L Rivist Itlin delle Sostnze Grsse, 8, Cyuel, J. A., Rd, M., Pérez-Cmino, M., Beniss, M., Adelziz, E., & Guind, A. (8). Chrteriztion of rtisnlly nd semiutomtilly extrted rgn oils from Moroo. Europen Journl of Lipid Siene nd Tehnology,, Chrrouf, Z., El Hmhi, H., Mlli, S., Liitr, G., & Guillume, D. (6). Influene of rosting nd seed olletion on rgn oil odornt omposition. Nturl Produt Communitions,, 99. Chrrouf, Z., & Guillume, D. (999). Ethnoeonomil, ethnomedil nd phytohemil study of Argni spinos (L.) Skeels. Journl of Ethnophrmology, 67, 7. Chrrouf, Z., & Guillume, D. (7). L huile d rgne. Composition et propriétés himiques de l huile d rgne. In L. Kenny & I. De Zorowski (Eds.), Atls de l rgnier et de l rgnerie (pp. 6 69). IAV Hssn II: Rt. Chrrouf, Z., & Guillume, D. (8). Argn oil: Ourrene, omposition nd impt on humn helth. Europen Journl of Lipid Siene nd Tehnology,, Chrrouf, Z., Guillume, D., & Driouih, A. (). The rgn tree, n sset for Moroo. Biofutur,, 7 [in Frenh]. Chrrouf, Z., Hrhr, H., Ghry, S., & Guillume, D. (8). Enhning the vlue of rgn oil is the est men to sustin the rgn grove eonomy nd iodiversity. Olégineux, Corps Grs, Lipides,, Codex Alimentrius (99). Fts, oils nd relted produts, nd ed. Rome Codex Stndrd for nmed Vegetle Oils Codex-STAN, Vol. 8. [Amended, ]. DGF (8). Deutshe Einheitsmethoden zur Untersuhung von Fetten, Fettprodukten, Tensiden und verwndten Stoffen. Stuttgrt: Wissenshftlihe Verlgsgesellshft. Eihner, K. (98). Antioxidtive effet of Millrd retion intermedites. In M. G. Simi & M. Krel (Eds.), Autoxidtion in food nd iologil systems (pp. 67 8). New York: Plenum Press. Gutierrez, F., & Fernndez, J. L. (). Determinnt prmeters nd omponents in the storge of virgin olive oil. Predition of storge time eyond whih the oil is no longer of extr qulity. Journl of Agriulturl nd Food Chemistry,, Gutierrez, F., Vron, I., & Ali, M. A. (). Reltion of idity nd sensory qulity with sterol ontent of olive oil from stored fruit. Journl of Agriulturl nd Food Chemistry, 8, 6. Hilli, M., Chrrouf, Z., El Aziz Soulhi, A., Hhimi, L., & Guillume, D. (). Influene of origin nd extrtion method on rgn oil physio-hemil hrteristis nd omposition. Journl of Agriulturl nd Food Chemistry,, Josen, C. (999). Sensory impt of lipid oxidtion in omplex food systems. Fett/ Lipid,, 8. Klu, C. M., Bedgood, D. R., Jr., Bishop, A. G., & Prenzler, P. D. (8). Chnges in virgin olive oil qulity during low-temperture fruit storge. Journl of Agriulturl nd Food Chemistry, 6,. Leitsätze für Speisefette und-öle. vom 7.. (997) (BAnz. Nr. 9 vom.. 997, GMBl. Nr. S. 86 vom ), geändert m.. (BAnz. Nr. 99 vom.., GMBl Nr. 8, 7 ff vom..). Lingnert, H., & Eriksson, C. E. (98). Antioxidtive effet of Millrd retion produts. Progress in Food & Nutrition Siene,, 66. Mrfil, R., Crer-Vique, C., Giménez, R., Bouzs, P. R., Mrtínez, O., & Sánhez, J. A. (8). Metl ontent nd physiohemil prmeters used s qulity riteri in virgin rgn oil: Influene of the extrtion method. Journl of Agriulturl nd Food Chemistry, 6,

7 B. Mtthäus et l. / Food Chemistry () 6 Mtthäus, B., & Brühl, L. (8). Why is it so diffiult to produe high-qulity virgin rpeseed oil for humn onsumption? Europen Journl of Lipid Siene nd Tehnology,, Morton, J. F., & Voss, G. L. (987). The rgn tree (Argni sideroxylon, spotee), desert soure of edile oil. Eonomi Botny,,. Rsrelli, L., Pssi, S., Ippolito, F., V, G., & De Simone, F. (). Rte of degrdtion of -toopherol, squlene, phenolis, nd polyunsturted ftty ids in olive oil during different storge onditions. Journl of Agriulturl nd Food Chemistry,, Shhidi, F., & Wnsundr, P. K. J. (99). Phenoli ntioxidnts. Critil Review in Food Siene nd Nutrition,, 67. Trutwein, E. A., & Demonty, I. (7). Phytosterols: Nturl ompounds with estlished nd emerging helth enefits. Olégineux, Corps Grs, Lipides,, Verhé, R. (9). Prodution of oil nd vlue-dded nutreutils from gri-food proessing y-produts. In: th Interntionl flvor onferene: Reent dvnes in food flvor hemistry, Skithos, Greee.