Effect of Extrusion on the Hydrophilic Antioxidant Capacity of Four Whole Grains

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1 Journl of Foo n Nutrition Reserh, 2014, Vol. 2, No. 2, Aville online t Siene n Eution Pulishing DOI: /jfnr Effet of Extrusion on the Hyrophili Antioxint Cpity of Four Whole Grins Lingxio Yng, Hui Zhng *, Lilin Cheng, Zhonghu Gu, Dn Hu, Xigung Qi, Hifeng Qin, Li Wng Stte Key Lortory of Foo Siene n Tehnology & Shool of Foo Siene n Tehnology, Jingnn University, Wuxi, Chin *Corresponing uthor: zhnghui@jingnn.eu.n Reeive Ferury 18, 2014; Revise Mrh 06, 2014; Aepte Mrh 10, 2014 Astrt Cerel grins re generlly sujete to therml tretment efore onsumption. However, few t re ville on totl phenoli ontent (TPC), egree of strh geltiniztion, phenoli is, n ntioxint pity of extrue whole grins se on trolox equivlent ntioxint pity (TEAC), DPPH ril svenging tivity, n ferri reuing ntioxint potentil (FRAP). Four whole grins, rown rie, whet, mize, n rley were exmine in this stuy. The free n oun TPChnge signifintly (p < 0.05) fter extrusion. Morever, het n egree of strh geltiniztion oul ffet the oun TPC. In oun frtion, the ntioxint pity ws iretly influene y TPC. Extrusion ( C) n retin or improve the ntioxint pity in its free n oun frtions. Phenoli is re stle in their oun form. Results showe tht the oun TPC n totl phenoli is hve strong reltionship ginst ntioxint pity, initing tht TPC is the mjor ntioxint in the oun frtion. Keywors: whole grins, totl phenoli ontent, ntioxint pity, HPLC Cite This Artile: Lingxio Yng, Hui Zhng, Lilin Cheng, Xigung Qi, Hifeng Qin, n Li Wng, Effet of Extrusion on the Hyrophili Antioxint Cpity of Four Whole Grins. Journl of Foo n Nutrition Reserh, vol. 2, no. 2 (2014): oi: /jfnr Introution Cerel grins re tritionl Asin stple foos n mjor soure of ily energy intke. Nowys, onsumers prefer refine grins to whole grins euse of the rough texture n unplesnt tstes of whole grins. However, most of the ntioxints re remove uring the refining proess [1,2]. Epiemiologi stuies hve shown tht the intke of whole grin is ssoite with positive helth enefits, suh s lowere risks of hroni iseses like oronry hert iseses (CHD), type II ietes, n ner long with reue mortlity risk. This is ttriute in prt to the phytohemils lote in the eile prts of the whole grin, i.e. the rn, germ, n enosperm [3,4,5,6,7]. Phytohemils, whih inlue terpenois, phenols, n lklois, re iotive omponents of plnts tht provie mny helth enefits. It is elieve tht their ntioxint tivities re key to the protetion ginst some hroni iseses [8,9]. Therefore, enourging people to onsume more whole grins on ily sis ppers to e of gret importne. There hs een muh reserh into the ntioxint tivity of whole grins. Most stuies hve fouse on the use of vrious orgni solvents to fully extrt the ntioxints [10,11]. However, some stuies hve shown tht suh extrtion methos unerestimte the ntioxint pity of whole grins euse most of the ntioxints re in n insolule oun form, i.e. they re oun to ell wll mteril [12,13]. Therefore, oth free n oun phenoli ontents shoul e onsiere. Most of the literture esriing the ntioxint pity of whole grinsis fouse on the rw mterils [11,12,14,15,16,17]. Unlike vegetles n fruits, whole grins n hrly e eten y humns without eing ooke. Therefore, stuies on the ntioxint pity of unproesse whole grins pper to e inequte euse ifferent proesses my hve iffering effets on the ntioxint ontent of whole grin. To the est of our knowlege, only limite numer of stuies hve reporte the ntioxint ontent of proesse whole grins [18,19]. Thus, it is neessry to investigte the ntioxint pity of proesse whole grins so tht we n urtely evlute their ntioxint tivity. The ojetive of this stuy ws to investigte the effets of extrusion ( C) on phytohemil ontent (i.e. the totl phenoli ontent (TPC), feruli i ontent n p-oumri i ontent), egree of strh geltiniztionn ntioxint pity (i.e. DPPHril svenging pity, trolox-equivlent ntioxint pity [TEAC] n ferri reuing ntioxint potentil [FRAP]) of four whole grins (i.e.mize, whet, rown rie, n rley). 2. Mterils n methos 2.1. Mterils

2 81 Journl of Foo n Nutrition Reserh Folin-Ciolteu s regent, 6-hyroxy-2,5,7,8- tetrmethylhromn-2-roxyli i (Trolox), 2,2'- zino-is(3-ethylenzothizoline-6-sulphoni i) (ABTS), 2,2-iphenyl-1-pirylhyrzyl (DPPH), Tk- Distse from Aspergillus oryze, feruli i, n p- oumri i were purhse from Sigm-Alrih (St. Louis, MO). 2,4,6-Tri(2-pyriyl)-s-trizine (TPTZ) ws purhse from Alin Tehnology Corportion (Shnghi, Chin). Methnol n etonitrile of HPLC gre were purhse from J&K Sientifi Lt (Beijing, Chin). Other hemils use in this stuy were of nlytil gre n purhse from Sinophrm Chemil Regent Co., Lt. (Shnghi, Chin). Whole grin mize, whet, rown rie n rley were purhse from lol supermrket in Wuxi, Chin. All whole grins were store t -20 C efore use Smples Preprtion Whole grins were groun (Moel FW100 griner, Tinjin Tisite Instrument Co., Lt., Tinjin, Chin) to proue fine power tht woul pss through 60 mesh sieve. The grouns were store t -20 C efore use. Extrue smples: Whole grin power (1 kg) ws otine s esrie ove, n the wter ontent ws juste to 25%. Extrusion ws rrie out on twinsrew extruer (Moel POLYLAB, Thermo Fisher Sientifi In., Msshusetts, USA) t onstnt 100 r/min srew spee n 60 g/min mss flow rte. Four rrel temperture profiles were use: C, C, C, n C. All the smples otine ove were le to e onsume n then groun to proue fine power tht woul pss through 60 mesh sieve. The grouns were store t -20 C efore extrtion Determintion of the Moisture Content For etermintion of the ry weight (DW), pproximtely 1 g of rw or proesse smple ws rie in rying oven (Moel DHG-9203A, Shnghi Yiheng Sientifi Instrument Co., Lt, Shnghi, Chin) t 105 C for 4 h until the smple rehe onstnt weight Phenoli Extrts Extrtion of free-solule n insolule-oun phenoli ompouns ws oring to the metho esrie y Sosulski [20] n moifie in our l. Free-solule phenol: Whole grin flour smples (10g) were extrte twie with 100 ml of 80% (v/v) queous ethnol for 10 min t mient temperture n entrifuge t 4000 r/min for 10 min t 20 C. The superntnts were ollete, omine, n then evporte uner vuum t 35 C in rotry vuum evportor (Moel RV10 si, Gungzhou IKA Sientifi Instrument Co., Lt., Gungzhou, Chin) to ryness n reonstitute in 100 ml of wter efore two extrtions with n-hexne to remove lipophili ontminnts. Insolule-oun phenols: After the extrtion of free-solule phenols, the resiue ws igeste with 100 ml of 2 M NOH t mient temperture for 1 h, n n ultrsoni lening instrument (Moel KQ2200DE, Kunshn Ultrsoni Instrument Co., Lt., Kunshn,Chin) ws use uring the hyrolysis. The resultnt hyrolyste ws iifie to ph 6 with HCl n extrte three times with ethyl ette. The ethyl ette frtion ws ollete n evporte to ryness uner vuum t 35 C n reonstitute in 100 ml of wter, then extrte twie with n-hexne to remove lipophili ontminnts Determintion of TPC Briefly, 1 ml of the extrt ws thoroughly mixe with 1 ml of Folin-Ciolteu regent n 3 ml of 7.5% (w/v) soium ronte solution [21]. The mixture ws llowe to stn t mient temperture for 2 h. The sorne ws mesure t λ = 765 nm with Visile Spetrophotometer (Moel 722S, Wuxi Ke Intelligent Instrument Co., Lt., Wuxi, Chin). TPC ws etermine y mens of lirtion urve prepre y using glli i n expresse s mirogrm glli i equivlent (GAE) per grm of whole grin (DW). Dt re reporte s men ± stnr evition (SD) for t lest three replitions Determintion of Strh Geltiniztion Degree The egree of strh geltiniztion of the extrue whole grins ws etermine oring to Bhtthry [22]. Briefly, 3 flsks of 100 ml were prepre whih were mrke s A 1, A 2 n B, respetively. 1 g of smple ws ple in oth A 1 n A 2 efore 50 ml of wter ws e into the 3 flsks. In orer to thoroughly geltinize the strh, A1 ws oile in wter for 20 min efore it ws oole own to mient temperture immeitely. Then, A 1, A 2, B were respetively e with 5 ml of 5% (w/v) Tk-Distse whih were lter wter the in 38 C for 2 h. Enzymti hyrolysis ws puse y ing 2 ml of 1M HCl. The hyrolystes in A 1 n A 2 were otine fter entrifuging t 4000 r/min n wter ws e to the volume of 100 ml. Mixing 10 ml of the hyrolyste with 10 ml of 0.01 M ioine solution, 2 ml of 1 M H 2 SO 4 n 18 ml of 0.1 M NOH, then the mixture ws titrte y 0.01 M N 2 S 2 O 3. V 1, V 2, V 0 represents the volume titrte for A 1, A 2, B, respetively. Strh geltiniztion egree ws lulte y the following formul: SGD (%) = [(V 0 -V 1 )/( V 0 -V 2 )] Svenging Effets on DPPH Ril. Briefly, 0.1 ml of the extrte solution ws mixe with methnoli DPPH solution for whih the sorne t λ = 515 nm ws ilute y methnol to 0.60 ± 0.02 [23]. The sorne of the mixture ws mesure t the en of the 30 min of inution. The svenging effet ws lulte oring to the following eqution: DPPH ril svenging rte (%) = [(A 515 ontrol A 515 smple) /A 515 ontrol] 100, where A ontrol = sorne of DPPH ril + methnol, A smple = sorne of DPPH ril + whole grin extrt, n methnol ws regre s lnk. DPPH ril svenging ility ws expresse s the svenging rte (%) per grm of whole grin (DW). Dt re reporte s men ± SD for t lest three replitions Determintion of TEAC

3 Journl of Foo n Nutrition Reserh 82 ABTS ws prepre oring to Re [24]. The ABTS ws then ilute with wter to proue working solution with n sorne of 0.70 ± 0.02 t 734 nm. Eh smple (0.1 ml) ws mixe with 3.9 ml of working solution, n the eolortion ws mesure t 734 nm fter 10 min. TEAC ws etermine y mens of proper lirtion urve rete y using trolox t ifferent onentrtions. Dt re reporte s men ± SD for t lest three replitions Determintion of FRAP Briefly, 0.1 ml of eh smple ws mixe thoroughly with 3.0 ml of FRAP regent efore the mixture ws inute for 30 min t 37 C in wter th[25]. The sorne ws mesure t λ = 593 nm. Different onentrtions of FeSO 4 were use to rete the lirtion urve. FRAP vlues were otine from the lirtion urve oring to the sorne of eh smple n expresse s mm FeSO 4 equivlent per grm of whole grin (DW) Determintion of Phenoli Ais y HPLC Feruli n p-oumri i ontents in free n oun phenoli frtions were etermine y HPLC [15]. Briefly, 10μL of the extrt ws nlyze y HPLC (1260 Infinity, Agilent Tehnologies Co., Lt., Snt Clr, USA) equippe with G1311C quternry pump, G1316A olumn omprtment, n G1315D ioe rry etetor. Seprtions were performe on Wters LC-18 olumn ( mm, 5 μm), with the olumn flow rte set to 0.5 ml min -1 n the olumn temperture set to 25 C. The moile phse onsiste of formi i/wter (1:99; v/v) (eluent A) n methnol/etonitrile/formi i (94:5:1; v/v/v) (eluent B). Grient elution ws use s follows: 0 min, 20% B; 10 min, 30% B; 15 min, 40% B; 18 min, 45% B; 20 min, 50% B; 30 min, 70% B; n 40 min, 85% B. Feruli n p-oumri i were ientifie y ompring the reltive retention times of elute ompouns with those of pure stnrs t λ = 320 nm. Feruli n p-oumri is were quntifie y n externl stnr metho Sttistil Anlysis. Vlues re shown s men ± SD (n = 3). Anlysis of vrine (one-wy ANOVA) ws use to test ifferenes in vlues etween tretments, with signifine level of α = Reltionship etween the vriles were etermine y Person s regression nlysis. All sttistil nlysis were performe with SPSS softwre (version 19). 3. Results n Disussion 3.1. TPC of Rw n Extrue Grins The TPC of free n oun frtions (free n oun phenoli extrts)of rw n extrue whole grins rnge from ± 14.1 to ± 16.4 μg GAE/g DW n from ± 13.9 to ± 42.8 μg GAE/g DW, respetively (Figure 1). There were signifint ifferenes etween the rw n extrue whole grins for oth free n oun frtions. Phenoli ontent (μg GAE equiv / g DW)) Free Boun Totl=Free+Boun A Brown Rie e Phenoli ontent (μg GAE equiv / g DW)) Free Boun Totl B Whet 0 0 rw extrue (110) extrue (120) extrue (130) extrue (140) rw Phenoli ontent (μg GAE equiv / g DW)) 2000 Free 1800 Boun Totl e C Mize e Phenoli ontent (μg GAE equiv / g DW)) e extrue (110) Free Boun Totl extrue (120) extrue (130) extrue (140) D Brley 0 0 rw extrue (120) extrue (110) extrue (140) extrue (130) rw extrue (120) extrue (110) extrue (140) extrue (130) Figure 1. TPC of rw n extrue whole grins in free, oun n totl frtions. Differenes in vlues mong free, oun n totl frtions mrke with ifferent letters re signifint (p <0.05).The letter represents the highest vlue

4 83 Journl of Foo n Nutrition Reserh With respet to free frtions, the TPC of rown rie (Figure 1 A) ws ± 8.0 μg GAE/g DW n signifintly erese (p < 0.05) y 63%, 65%, 68%, n 72% fter extrusion ( C), respetively. Similr trens were oserve for mize n rley (Figure 1 B, D). However, the TPC of oth mize n rley erese less thn tht of rown rie uner the sme onition, initing the TPC of rown rie is more suseptile thn the others uring extrusion. It is esy to omprehen tht the TPC erese s the temperture inrese euse more TPC n e eompose t higher temperture. Moreover, Chnrsekr [26] inferre tht uring therml tretment, omplexes n form etween phenolis n mromoleules, mking the phenolis less extrtle. Interestingly, the TPC of whet (Figure 1 B) signifintly inrese y 8%, 16% n 8% fter extrusion ( C), respetively. The inrese in the free phenoli ontent of whet inites tht extrusion my lso hve postive effet on whet. Dewnto [27] reporte signifint inrese of free TPC in sweet orn uring hyrotherml tretment n ttriute the inrese to the liertion of the phenoli ompouns from their oun forms [18]. With respet to oun frtions, the TPC of rown rie (Figure 1 A) ws ± 5.4 μg GAE/g DW whih signifintly erese y 32%, 25%, 10%, n 45% fter extrusion ( C), respetively (p < 0.05). As for whet n mize, similr trens were lso oserve (Figure 1 B, C). Interestingly, TPC of rley (Figure 1 D) inrese y 31%, 91%, 43%, n 11% fter extrusion ( C), respetively (p < 0.05). As is esrie ove, phenoli ompouns oul e relese from their oun forms fter proessing euse of the het. Tht proly is the reson why there will e negtive effet of extrusion on the oun TPC of the whole grins. It is noteworthy tht positive effet of extrusion on the oun TPC ws lso oserve in rley. However, suh phenomenon h never een reporte in previous stuies [18,19,27,28]. It might e expline tht extrusion my help the whole grins to e igeste more thoroughly thn the rw ones, whih my hve me the oun TPC esier to lierte n relese more oun TPC uring hyroliztion. After etermining the egree of strh geltiniztion (Tle 1), we foun tht the egree of strh geltiniztion inrese s the temperture inrese. However, no signifint enhnements were foun of the vlues fter the temperture inrese to the ertin point. As for rown rie, whet n mize, the temperture is 130 C. But for rley, the temperture is 120 C. Therefore, the enhnement of egree of strh geltiniztion my hve some effets on improving the oun TPC. Previous stuies reporte tht the igestiility of nutrients n phytohemils in erel grins oul e improve uring proessing ue to the geltiniztion of strh [28,29] Compre with the other extrusion temperture, there ws n pprent inrese fter extrusion t 130 C for rown rie, whet n mize, n for rley t 120 C. As for rown rie, whet n mize, the het erese the oun TPC t first. With the egree of strh geltiniztion inrese, enhnement of the oun TPC grully ompenste the loss of the oun TPC whih is use y het. However, fter the egree of strh geltiniztion stoppe inresing, the het strte to erese the oun TPC gin. As for rley, the egree of strh geltiniztion inrese the oun TPC t first euse the egree of strh geltiniztion rehe to the mximum vlue t lower temperture thn the others. Similrly, the het strte to erese the oun TPC gin fter the egree of strh geltiniztion stoppe hnging. With respet to totl frtions, the hnge of TPC ws lso signifint (p < 0.05) fter extrusion ( C). The totl TPC of rown rie (Figure 1 A) ws ± 2.6 μg GAE/g DW whih signifintly erese y 51%, 50%, 46%, n 61% fter extrusion ( C), respetively (p < 0.05). The sme trens were lso oserve for the other grins (Figure 1 B, C). As for the rley, however, it inrese y 7%, 37%, 12% n 7%. Corresponingly, these trens oserve were similr s we oserve on oun TPC initing tht the ltertion ourre on totl TPC is minly eie y oun TPC, though totl TPC is the omintion of oth free n oun TPC. This might e the reson of oun TPC s suffiieny in mount n stleness ginst het. The ertin tempertures on whih the totl TPC reenhnement took ple expline tht het n the egree of strh geltiniztion oul still ffet the totl TPC. Tle 1. Degree of strh geltiniztion of extrue whole grins uner ifferent tempertures Degree of strh geltiniztion / % Temperture / C Brown rie 84.2 ± ± ± ± 1.1 Whet 85.1 ± ± ± ± 0.6 Mize 82.7 ± ± ± ± 0.6 Brley 91.5 ± ± ± ± 0.8 Vlues in the tle re ll expresse s men ± SD with 3 replitions.the vlues in eh row hving the sme letter re not signifintly ifferent (p > 0.05). The letter represents the highest vlue in eh row. From the phenomenon ove, it is resonle to infer tht the oun TPC of whole grins ws spontneously ffete y het whih les to the loss of oun TPC n egree of strh geltiniztion whih helps to inrese the oun TPC. Perhps the free phenols oul permete into the strh n wrppe y it uring the proess of strh geltiniztion whih les to the protetion of some free TPC from eing eompose y het, n then e relese uring the extrtion of oun phenols whih in turn inreses the oun TPC. Boun TPC, however, oul hrly inrese s the temperture keep liming up ue to the higher het oul still eompose the free phenols wrppe in the strh n relese the phenols from their oun form into free form. Beuse of oun TPC s suffiieny n stleness, the ltertion of totl TPC ws similr to tht of oun TPC whih mens oun TPC plys ominnt role on the ltertion of the totl TPC uring extrusion. Therefore, extrusion n signifintly

5 Journl of Foo n Nutrition Reserh 84 hnge TPC of whole grins oth in free n oun frtions (p < 0.05). Both the het n the egree of strh geltiniztion oul ffet TPC of whole grins. Therefore, opting n pproprite temperture to proess whole grins n retin or improve the TPC to the highest extent Antioxint Cpity of Rw n Extrue Grins To properly evlute the ntioxint pity of rw n extrue whole grins, DPPH ril svenging tivity, TEAC n FRAP were use to etermine the ntioxint pity. DPPH n ABTS rils re svenge y ntioxints through the ontion of hyrogen to form olourless ompouns, n the reution of their olour oul e quntifie t the wvelength of 515 nm n 734 nm. FRAP ssy is use to etermine the ility of the ntioxint to reue Fe 3+ to Fe 2+ with the presene of TPTZ t low ph. One Fe 3+ is reue to Fe 2+, lue ompoun Fe 2+ -TPTZ oul e forme n the olour oul e quntifie t the wvelength of 593 nm[16]. In the present stuy, the TEAC n FRAP ssy ws performe in n queous system, thus only the hyrophili ntioxint pity ws mesure. In the free frtion of rown rie, the ntioxint pity hnge signifintly (p < 0.05) fter extrusion (Tle 2). The results showe tht over hlf of its initil TEAC n FRAP vlue were lost uring extrusion ( C). A similr tren ws lso oserve in the DPPH ril svenging ility. As for whet, extrue whets exhiite stronger ntioxint pity thn the rw one. Its DPPH ril svenging ility signifintly inrese (p < 0.05) y 38%, 259%, 111%, n 98% fter extrusion ( C), respetively. Similr results were lso otine with the TEAC vlue. However, FRAP vlue erese slightly fter proessing exept for extrusion (120 C), whih inrese y 74% (p < 0.05). It is noteworthy tht remrkle inrese in TEAC vlue, DPPH ril svenging ility, n FRAP vlue ws otine fter extrusion t 120 C. As for mize, oth TEAC n FRAP vlues i not signifintly hnge (p > 0.05) uring extrusion ( C), wheres there is slight erese (p < 0.05) fter extrusion t 140 C. In ontrst, the FRAP vlue signifintly erese fter extrusion ( C). As for rley, no signifint inrese (p >0.05) ws foun fter extrusion ( C) for TEAC vlue. A similr tren ws lso shown for FRAP vlue. However, DPPH ril svenging ility signifintly inrese. Tle 2. TEAC, DPPH, n FRAP vlues in the free n oun frtions of unproesse n proesse grins TEAC (μmol Trolox equiv/g DW) DPPH, (Inhiition rte per grm DW) FRAP (μmol FeSO 4 equiv/g DW) Smples Free Boun Free Boun Free Boun Brown rie Rw 4.52 ± ± ± ± ± ± 0.26 Extrue (110 C) 1.15 ± ± ± ± ± 0.20 e 4.84 ± 0.11 Extrue (120 C) 1.77 ± ± ± ± ± 0.26 e 5.49 ± 0.12 Extrue (130 C) 1.83 ± ± ± ± ± ± 0.24 Extrue (140 C) 1.87 ± ± 0.06 e 1.59 ± ± ± ± 0.11 Whet Rw 3.02 ± ± ± ± ± ± 0.80 Extrue (110 C) 3.77 ± ± ± ± ± ± 0.36 Extrue (120 C) 5.82 ± ± ± ± ± ± 0.23 Extrue (130 C) 4.22 ± ± ± ± ± ± 0.28 Extrue (140 C) 3.21 ± ± ± ± ± ± 0.23 Mize Rw 3.94 ± ± ± ± ± ± 0.38 Extrue (110 C) 3.89 ± ± ± ± ± ± 0.43 Extrue (120 C) 4.20 ± ± ± ± ± ± 0.60 Extrue (130 C) 4.22 ± ± ± ± ± ± 0.72 Extrue (140 C) 3.43 ± ± ± ± ± ± 0.40 Brley Rw 5.56 ± ± 0.28 e 3.14 ± ± ± ± 0.31 Extrue (110 C) 6.09 ± ± ± ± ± ± 0.62 Extrue (120 C) 6.23 ± ± ± ± ± ± 1.40 Extrue (130 C) 6.20 ± ± ± ± ± ± 0.71 Extrue (140 C) 6.28 ± ± ± ± ± ± 0.44 Vlues in the tle re ll expresse s men ± SD with 3 replitions n referre to the ry weight. The vlues otine y the metho esrie efore were relulte n referre to one grm of rie weight. The vlues in eh olumn hving the sme letter re not signifintly ifferent (p > 0.05).The letter represents the highest vlue in eh olumn. In the oun frtion of 4 grins, we foun similr tren of the ntioxint pity (TEAC, DPPH ril svenging ility n FRAP) of rown rie with its oun TPC. Compre with the results shown in Figure 1 n Tle 2, the ntioxint pity of whet, mize, n rley ws lso in line with their oun TPC fter proessing. Correltion nlysis (Tle 4) showe sttistilly high positive orreltion etween TPC n its ntioxint pity (for TEAC: r = 0.988, p < 0.01; for DPPH: r = 0.978, p < 0.01; for FRAP: r = 0.979, p < 0.01). The results oul e expline y the ft tht oun TPC is minly responsile for the ntioxint pity in its

6 85 Journl of Foo n Nutrition Reserh oun form. The hnge in oun TPC oul iretly reflet vrition in the ntioxint pity of whole grins. In ition, orreltion nlysis etween totl TPC n ntioxint pity ws teste. The results (Tle 4) still showe sttistilly high positive orreltion etween totl TPC n its ntioxint pity (for TEAC: r = 0.914, p < 0.01; for DPPH: r = 0.768, p < 0.01; for FRAP: r = 0.937, p < 0.01). Though the orreltion oeffiient etween totl TPC n ntioxint pity erese little for the use of free TPC, high positive orreltion etween them still shows tht TPC is the min ntioxint of whole grin. To summrize, the ntioxint pity of these four whole grins n e signifintly ffete y extrusion oth in free n oun frtions. In the free frtion, the ntioxint pity of extrue whet n e well retine or improve uring proessing, whih oul e ontriute y the enhnement of the free TPC in whet euse the free TPC re etter extrte fter extrusion long with some other ntioxints (e.g. mino i). A previous stuy lso foun remrkle enhnement of ntioxint pity fter proessing[30]. However, rown rie lost high proportion of its originl ntioxint pity fter proessing, ompre with the other three grins, whih my emonstrte tht the ntioxints in rown rie re more vulnerle n thermlly sensitive thn the others. Although the FRAP, TEAC, n DPPH ssys use in this stuy were se on vrie hemil priniples, the vlues of DPPH ril svenging tivity were reltively higher thn tht of TEAC when ompre with oth of their originl vlues. Beuse DPPH test ws performe in the methnoli system inste of the queous system, whih emonstrte tht the ntioxint might exert higher ntioxint pity in the methnoli system thn queous system. Previous stuies foun lower ntioxint pity in polr solvents euse hyrogen oning my use rmti hnges in the H-tom onor tivities of phenoli ntioxints [31M32]. As for the oun frtion, the vrition in the ntioxint pity of the 4 grins is ssoite with the hnge in its oun TPC, whih inites tht the ntioxint pity is minly rule y its oun TPC. Informtion gthere y previous stuies hs suggeste the oun TPC my survive upper gstrointestinl igestion onitions n reh the olon to exert its helth enefits lolly fter sorption [6,12] Content of Phenoli Ai of Rw n Extrue Grins As reporte y previous stuies [33,34], feruli n p- oumri is re regre s the mjor phenoli is in whole grins. Tle 3 shows the ontent of feruli n p- oumri is in the free n the oun frtions for oth proesse n unproesse whole grins. Tle 3. Content (mirogrms per grm of rie weight) of feruli i n p-oumri i in free n insolule oun phenoli extrts in ifferent smples Free (μg/g DW) Boun (μg/g DW) Smples Feruli i p-oumri i Totl, Feruli i p-oumri i Totl, Brown rie Rw ± ± ± ± ± ± 4.12 Extrue (110 C) 1.66 ± ± ± ± ± 0.12 e ± 2.35 Extrue (120 C) 9.29 ± ± ± ± ± ± 2.36 Extrue (130 C) 5.00 ± ± 0.00 e 6.31 ± ± ± ± 1.69 Extrue (140 C) 0.89 ± 0.01 e 4.02 ± ± ± 1.10 e ± ± 1.48 e Whet Rw ± ± ± ± ± ± 0.05 Extrue (110 C) 4.74 ± ± ± ± ± ± 4.74 e Extrue (120 C) 4.39 ± ± ± ± ± ± 9.89 e Extrue (130 C) 1.34 ± 0.01 e 1.19 ± ± 0.02 e ± ± ± 4.03 Extrue (140 C) 0.99 ± 0.01 e 0.91 ± ± 0.03 e ± ± ± 1.62 e Mize Rw ± ± ± ± ± ± 6.18 Extrue(110 C) ± ± ± ± ± ± 6.54 Extrue (120 C) 2.85 ± ± ± ± ± ± 3.24 Extrue (130 C) 1.62 ± ± ± 0.03 e ± ± ± 3.72 Extrue (140 C) 1.22 ± ± ± 0.07 e ± 1.81 e ± ± 2.96 e Brley Rw ± ± ± ± ± ± 2.69 Extrue (110 C) 3.29 ± ± ± ± ± ± 4.97 Extrue (120 C) 5.01 ± ± ± ± ± ± 5.44 Extrue (130 C) 6.09 ± ± ± ± ± ± 3.35 Extrue (140 C) 5.06 ± ± ± ± 3.46 e ± ± 3.56 e Vlues in the tle re ll expresse s men ± SD with 3 replitions n referre to the ry weight. The totl vlues were otine y summing eh single replite of eh ompoun. The vlues in eh olumn hving the sme letter re not signifintly ifferent (p > 0.05). The letter represents the highest vlue in eh olumn. In the free frtion of rown rie, the ontent of feruli n p-oumri is ws 49.9 ± 0.5 n 30.6 ± 0.7 μg/g DW. Aout 95%, 82%, 92%, n 94% of its totl phenoli is were lost fter extrusion ( C). The negtive effet of extrusion on the totl phenoli is is very notle (p < 0.05). A similr tren ws lso oserve in whet, mize, n rley. Over 70% of their totl free phenoli i were lost, whih inites some oxition

7 Journl of Foo n Nutrition Reserh 86 took ple uring extrusion. In ontrst, other uthors i not fin ny signifint erese in totl phenoli is ontents fter extrusion ( C) of ukwhet grot, perhps ue to ifferent onitions n ifferent grins [19]. A previous stuy hs reporte tht phenoli is oul e relese from their oun form into the free form to inrese the phenoli ontent in the free frtion [27]. However, no inrese ws foun for feruli or p-oumri is fter extrusion in the present stuy. Perhps the free phenoli is re very vulnerle in its free form, whih oul e soon eompose fter it is relese from its oun form uring extrusion ( C). In ition, the free phenoli is oul lso permete into the strh uring extrusion leing to the erese of their ontents. Correltion nlysis (Tle 4) showe no signifint reltionship etween totl phenoli i ginst ntioxint pity (for TEAC: r = 0.058, p > 0.05; for DPPH: r = 0.164, p > 0.05; for FRAP: r = 0.221, p > 0.05), euse most of the phenoli is were eompose fter proessing. It lso inites tht the totl phenoli is re not the mjor omponents in free TPC. Tle 4. Correltion nlysis of ntioxint pity n ontent of ntioxint ompouns of rw n extrue grin Totl phenoli ontent Totl phenoli i ontent Free phenoli extrts TEAC ** n.s. DPPH ** n.s. FRAP ** n.s. Boun phenoli extrts TEAC ** ** DPPH ** ** FRAP ** ** Free + Boun phenoli extrts TEAC ** ** DPPH ** ** FRAP ** ** **p < 0.01 n.s.: not signifint Both feruli i n p-oumri i re onsiere. Both free n oun frtions re onsiere. In the oun frtion of rown rie, the ontents of feruli n p-oumri is re ± 1.0 n ± 3.2 μg/g DW, whih is respetively over 6 n 4 times higher thn the free frtion of the phenoli i. Similr results from previous stuies support tht phenoli i re unnt in their oun form, espeilly for feruli i n p-oumri is, whih re ester-linke to ell wll polyshries [12,15,35]. Compre with the free phenoli is, only out 42%, 25%, 11%, n 44% of the totl phenoli is were lost fter extrusion ( C), respetively. The oun frtion of whet n mize h similr tren uring proessing. Phenoli is of rley lso erese fter extrusion (-15%, p < 0.05) t 140 C. However, extrusion ( C) signifintly inrese the phenoli is ontent of rley. Thus, oun phenoli is re less suseptile uring proessing ompre with the free phenoli is. Correltion nlysis (Tle 4) showe signifint reltionship etween totl phenoli i ginst ntioxint pity (for TEAC: r = 0.951, p < 0.01; for DPPH: r = 0.912, p < 0.01; for FRAP: r = 0.945, p < 0.01). The high orreltion etween ntioxint pity n totl phenoli i ontent lso revele the ft tht feruli i n p-oumri i re the mjor omponents in oun TPC. As for the whole feruli i n p-oumri i oth in free n oun phenoli extrts, orreltion nlysis (Tle 4) ws lso onute with ntioxint pity. Results showe sttistilly high positive orreltion etween them (for TEAC: r = 0.733, p < 0.01; for DPPH: r = 0.560, p < 0.01; for FRAP: r = 0.773, p < 0.01). This result revele ft tht whole phenoli i still hs gret impt on the ntioxint though most of the phenoli is were eompose uring extrusion whih shoul e ue to the suffiieny n stleness offere y oun phenoli i. 4. Conlusion In this stuy, we investigte hnges in the TPC, phenoli i ontent, egree of strh geltiniztion n ntioxint pity of ifferent whole grins fter extrusion ( C). The extrusion signifintly ffete the inexes ove. TPC, phenoli i ontent, n ntioxint pity n e retine or even enhne when n pproprite extrusion temperture is opte. Extrue (120 C) whet n rley suggests tht proesse whole grins my hve more helth enefits thn the rw mteril. In onlusion, the results provie useful informtion on how the ntioxint omponents, egree of strh geltiniztion n ntioxint pity hnges in ifferent whole grins uring extrusion. Thus, the results might e vlule in ommeril extrusion for etter retention or enhnement of the ntioxints in whole grins. Aknowlegement We grtefully knowlege Professor Hui Zhng n our ollegues for the exellent guine n tehnil ssistne uring this stuy. This stuy is finnilly

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