THE EFFECT OF ph, TEMPERATURE AND HEATING TIME ON INULIN CHEMICAL STABILITY

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1 SCIENTIARUM POLONORUMACTA At Si. Pol., Thnol. Alimnt. 1(2) 211, ISSN (print) ISSN (onlin) THE EFFECT OF ph, TEMPERATURE AND HEATING TIME ON INULIN CHEMICAL STABILITY Pwł Glibowski, Ann Bukowsk Univrsity of Lif Sins in Lublin Bkground. Inulin is storg rbohydrt found in mny plnts spilly in hiory root, Jruslm rtihok nd dhli tubr. It is prbioti with mny funtionl proprtis. In rlir rsrh onrning hmil stbility of inulin, th fft of ph on rhologil proprtis of inulin gls ws minly nlysd. In ths studis, th fft of tim, tmprtur nd ph on inulin hmil stbility ws not nlysd profoundly spilly onsidring th inulin onntrtions unbl to form gl strutur. Thus, th im of this work ws to study th fft of th bov mntiond ftors on inulin hmil stbility in wtr solution. Mtril nd mthods. 5% (w/w) inulin solutions t ph 1-12 wr htd t 2, 4, 6, 8 nd 1 C for 5-6 min. Aftr th nutrlistion th ontnt of rduing sugr ws nlysd ording to Millr s mthod (1959) with 3,5-dinitrosliyli id. Rsults. Th ondutd studis showd tht inulin hmil stbility t ph 4 drsd with n inrs of hting tim nd tmprtur. In nutrl nd bsi nvironmnt inulin ws hmilly stbl rgrdlss of hting tim nd tmprtur. Conlusions. Inulin pplition in food systms my b limitd in idi produts spilly whn htd bov 6 C during th prodution pross. Howvr, in produts t ph 5, th dgrdtion of this frutn dos not our vn t thrml prossing. Ky words: inulin, hydrolysis, tmprtur, ph INTRODUCTION Inulin is polyfrutn industrilly produd from hiory, though s storg rbohydrt it is lso found in big mounts in Jruslm rtihok nd dhli tubrs. Inulin is hin of frutos moluls onntd by -(2-1) glyosidi bonds, trmintd by on gluos molul. Th numbr of frutos moluls in n inulin hin vris from fw to mny tns [Ninss 1999]. Copyright by Wydwnitwo Uniwrsyttu Przyrodnizgo w Poznniu Corrsponding uthor Adrs do korspondnji: Dr inż. Pwł Glibowski, Dprtmnt of Milk Thnology nd Hydroolloids of Univrsity of Lif Sins in Lublin, Skromn 8, 2-74 Lublin, Polnd, -mil: [email protected]

2 19 P. Glibowski, A. Bukowsk Nowdys inulin my b purhsd in svrl diffrnt forms. Th most ommon r: ntiv inulin with n vrg dgr of polymriztion (DP) of 1-12, inulin ontining short hin frtions (with DP from 2 to 1) nd high prformn (HP) inulin with n vrg DP no lss thn 23. Rnt big intrst in inulin rsults from its prbioti proprtis. Inulin bus of its hmil strutur is not domposd by humn digstiv nzyms howvr, it is prft rbon sour for hlth-promoting prbioti btri. As not hydrolysd in humn gstrointstinl trt, inulin is rnkd s solubl fibr [Gibson nd Robrfroid 1995]. Bsids pro-hlthy proprtis inulin hs misllnous funtionl proprtis. On of th most importnt is its ft mimti proprty whih is sussfully usd in th prodution of myonnis [Bortnowsk nd Mkiwiz 26], mrgrin [Rooykkrs t l. 1994], prossd mts [Florowski t l. 21, Hdron t l. 27] or yogurts with drsd loriity nd full ft tst [Guvn t l. 25]. Inulin ws lso pplid in brd [Brin t l. 23], pst [Brnnn t l. 24] nd i-rm [El-Ngr t l. 22] prodution. Rntly, th fft of nvironmnt rtion on inulin hmil stbility hs bn nlysd in fw studis [Florkowsk t l. 24, Kim t l. 21, Glibowski nd Wsko 28]. Authors of thss studis fousd mostly on th fft of ph on rhologil proprtis of th gls formd by inulin. Inulin n form gl whn its onntrtion is bov 15% (w/w). In th quotd studis uthors onludd tht in th idi nvironmnt gltion proprtis of inulin wr dtriortd. Howvr, th fft of tim, tmprtur nd ph on inulin hmil stbility ws not nlysd profoundly, spilly onsidring th inulin onntrtions unbl to form gl strutur. Thus, th im of this work ws to study th fft of th bov mntiond ftors on inulin hmil stbility in wtr solutions. MATERIAL AND METHODS Th studid mtril ws inulin Frutfit TEX! kindly dlivrd by Snsus Oprtions C.V. (Roosndl, Th Nthrlnds). All othr hmils lik sodium hydroxid, hydrohlori id, 3,5-dinitrosliyli id (DNS), potssium sodium trtrt, sodium sulpht, phnol nd frutos wr of nlytil grd supplid by POCH Ktowi SA (Ktowi, Polnd). 5% (w/w) inulin solutions wr prprd by mixing inulin with distilld wtr (2 C) using MS 11HS mgnti stirrr (Wigo, Pistów, Polnd). Th ph of th inulin solutions ws subsquntly djustd to 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 11 nd 12 using 1M HCl,.1M HCl, 1M NOH or.1m NOH. Aftrwrds th solutions wr pourd to tst-tubs nd htd in wtr bth for 5, 1, 15, 2, 3, 4, 5 or 6 min. Th solutions with ph from 1 to 7 wr htd t 2, 4, 6, 8 nd 1 C whil th solutions with ph from 8 to 12 wr htd only t 1 C. For rdution sugr nlysis, th smpls wr nutrlizd immditly ftr hting using.1 or 1M HCl, or NOH solution nd ftrwrds oold to mbint tmprtur in th running tp wtr. Th Millr mthod [1959] ws usd for th quntittiv nlysis of th rduing sugr in inulin solutions. Adqutly dilutd smpls wr rtd with DNS id. Th intnsity of dvlopd olour ws msurd using sptrophotomtr (Spkol 11, Crl Ziss Jn). Frutos ws usd for th stblishmnt of stndrd urv. For th n-

3 Th fft of ph, tmprtur nd hting tim on inulin hmil stbility 191 lytil purpos th rduing sugr mount ws xprssd s rduing sugr prntg shr in totl sugr (inulin) ontnt. For th sttistil purposs nd figurs lrity th mn vlus wr drwn from th hting tims. Th dt wr nlysd by th Sttistil Anlysis Systm (SAS Entrpris Guid ) using th ANOVA produr for nlysis of vrin nd Studnt-Nwmn-Kuls t-tst for rnking th mns. RESULTS AND DISCUSSION Hting 5% inulin solution in strong idi nvironmnt (ph 1-3) usd intnsiv hydrolysis (Fig. 1-3). Th mount of unbound rduing sugr inrsd with hting tim nd tmprtur. In th nvironmnt with th lowst nlysd ph, hydrolysis prodd quit intnsly vn t not vry high tmprtur (4 C). Th highr tmprtur ws nssry to rls mor thn 6% rduing sugr whn th idity drsd. Th inulin brkdown ourrd whn th tmprtur rhd 8 C t ph 4 (Fig. 4) howvr, vn ftr hting t boiling wtr bth, only 2% rdution sugr ws rlsd. Studying th gltion proprtis of inulin Kim t l. [21] showd n impirmnt of gl strutur for 25% inulin gls produd t ph 3 nd lowr. Florkowsk t l. [24] notid wkr gltion for 2% inulin solution t ph 4, whilst 25% inulin gl hd ompt strutur. Vry similr fft on th txtur notid Glibowski nd Wsko [28]. Rdution sugr nlysis rvld its signifint inrs in th gls formd t ph lowr or qul 3, whih xplind th drs in gl hrdnss [Kim t l. 21, Glibowski nd Wsko 28]. Th inulin brkdown ourrd in n idi nvironmnt (ph < 4) whih usd loosning of th gl strutur. Th ontnt of rdution sugr ws vry similr in slightly idi nd nutrl nvironmnt t ph 5, 6 nd 7 rgrdlss of tim nd tmprtur of thrml trtmnt (Fig. 5-7). This trnd ws mintind t n lklin nvironmnt. Hting th smpls Rduing sugr shr, % ph 1 b b b b b b b d d d Tmprtur, C Fig. 1. Prntg shr of rduing sugr in totl sugr ontnt s fftd by hting tim nd tmprtur t ph 1. Dt r prsntd s mns ±stndrd dvition. Mns with diffrnt lttrs r signifintly diffrnt, p.5 At Sintirum Polonorum, Thnologi Alimntri 1(2) 211

4 192 P. Glibowski, A. Bukowsk Rduing sugr shr, % ph 2 b Tmprtur, C Fig. 2. Prntg shr of rduing sugr in totl sugr ontnt s fftd by hting tim nd tmprtur t ph 2. Dt r prsntd s mns ±stndrd dvition. Mns with diffrnt lttrs r signifintly diffrnt, p.5 Rduing sugr shr, % ph 3 d b b Tmprtur, C Fig. 3. Prntg shr of rduing sugr in totl sugr ontnt s fftd by hting tim nd tmprtur t ph 3. Dt r prsntd s mns ±stndrd dvition. Mns with diffrnt lttrs r signifintly diffrnt, p.5 t 1 C vn for t ph in th rng of 8-12 did not us th hng in th ontnt of rdution sugr (Fig. 8). Th nlysd rdution sugr ontnt t 2-3% lvl t ph highr thn 5 rsultd probbly from nturl prsn of simpl sugrs in th usd inulin powdr. Florkowsk t l. [24] ffirmd stbility of 2% inulin gls formd t ph > 5. Only th smpl with 15% inulin onntrtion did not form gl with th omplt strutur but this ws probbly usd by too low onntrtion to form thr dimnsion ntwork. Th nlysis of rduing sugr by two indpndnt rsrhrs groups showd

5 Th fft of ph, tmprtur nd hting tim on inulin hmil stbility 193 Rduing sugr shr, % ph 4 d d b Tmprtur, C Fig. 4. Prntg shr of rduing sugr in totl sugr ontnt s fftd by hting tim nd tmprtur t ph 4. Dt r prsntd s mns ±stndrd dvition. Mns with diffrnt lttrs r signifintly diffrnt, p.5 Rduing sugr shr, % ph 5 bd bd d bd b b bd bd bd bd d bd bd b bd bd b bd bd Tmprtur, C Fig. 5. Prntg shr of rduing sugr in totl sugr ontnt s fftd by hting tim nd tmprtur t ph 5. Dt r prsntd s mns ±stndrd dvition. Mns with diffrnt lttrs r signifintly diffrnt, p.5 low rduing sugr onntrtions in th gls formd t littl idi, nutrl nd lklin ph [Kim t l. 21, Glibowski nd Wsko 28]. In ontrst to th rsults obtind in this work, Kim t l. [21] notid littl inrs in rduing sugr onntrtion du to hting tmprtur inrs for th smpls htd t nutrl ph. As th tmprtur inrs usd onsidrbl drs in inulin glling proprtis thy supposd tht it rsultd from inulin moluls brkdown into shortr hins, whih ws indirtly onfirmd by th simpl sugr onntrtion inrs. Ths rsults did not orrobort with Glibowski nd Wsko [28] studis. Applying HPLC nlysis Glibowski nd Wsko [28] showd tht inulin is hmilly stbl vn t high tmprturs in th nvironmnt los to nutrl ph, whrs At Sintirum Polonorum, Thnologi Alimntri 1(2) 211

6 194 P. Glibowski, A. Bukowsk Rduing sugr shr, % ph 6 b b b b b b b b b b b b b b b b b Tmprtur, C Fig. 6. Prntg shr of rduing sugr in totl sugr ontnt s fftd by hting tim nd tmprtur t ph 6. Dt r prsntd s mns ±stndrd dvition. Mns with diffrnt lttrs r signifintly diffrnt, p.5 Rduing sugr shr, % ph 7 b b b b b b b b b b b b b b Tmprtur, C Fig. 7. Prntg shr of rduing sugr in totl sugr ontnt s fftd by hting tim nd tmprtur t ph 7. Dt r prsntd s mns ±stndrd dvition. Mns with diffrnt lttrs r signifintly diffrnt, p.5 th obsrvd dtriortion in inulin gltion proprtis rsultd from rystl hrtr of th inulin gl strutur. Th inulin gl strutur dpndd on th prsn of th rystl sds whih wr dissolvd t high tmprturs. Gnrlly, it n b onludd from this study, tht inulin n b pplid in food systms spilly s ft substitut. Food whih ontins onsidrbl mount of ft with ph lowr thn 4 is rr. Th ph of th most idi food (.g. yoghurt or kfir) in whih inulin is usd s ft substitut is nvr lowr thn 4. Wht is mor importnt, this idity pprs during mturtion i.. mximum t C in s of yoghurt mturtion. In this tmprtur rng, onsidrbl inrs in simpl sugr onntrtion ws obsrvd t ph 3, thus in n nvironmnt with 1 tims highr hydronium ion onntrtion.

7 Th fft of ph, tmprtur nd hting tim on inulin hmil stbility 195 Rduing sugr shr, % b b b b b b b b b b b b b ph Fig. 8. Prntg shr of rduing sugr in totl sugr ontnt s fftd by hting tim t 1 C in n lklin nvironmnt. Dt r prsntd s mns ±stndrd dvition. Mns with diffrnt lttrs r signifintly diffrnt, p.5 CONCLUSIONS 1. Inulin hmil stbility drss in n idi nvironmnt t ph 4 du to th hting tim nd tmprtur inrs. 2. In nutrl nd lklin nvironmnt inulin is hmilly stbl indpndntly of ph, hting tim nd tmprtur. 3. Inulin n hv limitd pplitions in idi foods (ph 4), spilly htd t tmprturs bov 6 C. 4. Inulin dgrdtion dos not tk pl in th produts with ph 5 htd up to 1 C. REFERENCES Bortnowsk G., Mkiwiz A., 26. Thnologil utility of gur gum nd xnthn for prodution of low-ft inulin-nrihd myonnis. At Si. Pol., Thnol. Alimnt. 5 (2), Brnnn C.S., Kuri V., Tudori C.M., 24. Inulin-nrihd pst: ffts on txturl proprtis nd strh dgrdtion. Food Chm. 86, Brin C.M.O., Mullr A., Snnll A.G.M., Arndt E.K., 23. Evlution of th ffts of ft rplrs on th qulity of wht brd. J. Food Eng. 56, El-Ngr G., Clows G., Tudori C.M., Kuri V., Brnnn C.S., 22. Rhologil qulity nd stbility of yog-i rm with ddd inulin. Int. J. Diry Thnol. 55, 2, Florowsk A., Budyt A., Krygir K., 24. Powstwni i włśiwośi żli inulinowyh [Forming inulin gls nd thir proprtis]. Żywn. Nuk. Thn. Jkość 3 (4) Supl., [in Polish]. Florowski T., Admzk L., Furts Hrnándz I., Bln Morno Frno M., Tybury A., 21. On wpływu stopni substytuji tłuszzu inuliną n wybrn wyróżniki jkośi modlowyh kiłbs [Influn of ft rplmnt with inulin on sltd proprtis of modl susgs]. Nuk Przyr. Thnol. 4, 5, #57 [in Polish]. At Sintirum Polonorum, Thnologi Alimntri 1(2) 211

8 196 P. Glibowski, A. Bukowsk Gibson G.R., Robrfroid M.B., Ditry modultion of th humn oloni mirobiot Introduing th onpt of prbiotis. J. Nutr. 125, Glibowski P., Wsko A., 28. Efft of thrmohmil trtmnt on th strutur of inulin nd its glling proprtis. Int. J. Food Si. Thnol. 43, Guvn M., Ysr K., Kr O.B., Hyloglu A.A., 25. Th fft of inulin s ft rplr on th qulity of st-typ low-ft yogurt mnuftur. Int. J. Diry Thnol. 58, 3, Hdorn R., Piinli P., Sutr M., 27. Ft rdution with inulin in wtr-boild susgs. AgrrForsh. 14, Kim Y., Fqih M.N., Wng S.S., 21. Ftors ffting gl formtion of inulin. Crbohyd. Polym. 46, Millr G.L., Us of dinitrosliyli id rgnt for dtrmintion of rduing sugrs. Anl. Chm. 31, Ninss K.R., Inulin nd oligofrutos. J. Nutr. 129, Rooykkrs M., Gruhn E., Vinn G., Innovtiv ft sprds ontining inulin. Dtsh. Milhwirtsh. 45, WPŁYW ODCZYNU ŚRODOWISKA, TEMPERATURY I CZASU OGRZEWANIA NA STABILNOŚĆ CHEMICZNĄ INULINY Wstęp. Inulin jst zpsowym węglowodnm obnym w dużyh ilośih w ykorii, dlii i topinmburz. Wykzuj hy prbiotyzn orz m wil włśiwośi funkjonlnyh. W dotyhzsowyh bdnih nd stbilnośią hmizną inuliny skupino się przd wszystkim n wpływi odzynu środowisk n hy rologizn tworzonyh przz inulinę żli. W prh ni bdno szzgółowo wpływu zsu, tmprtury i odzynu środowisk n stbilność hmizną inuliny w roztworh o stężnih unimożliwijąyh jj żlowni. Dltgo lm pry było zbdni wpływu wyminionyh zynników n stbilność hmizną inuliny w roztworh wodnyh. Mtriły i mtody. W lu przprowdzni nliz 5-prontow (w/w) roztwory inuliny o ph od 1 do 12 ogrzwno w tmprturz 2, 4, 6, 8 i 1 C, przz okrs od 5 do 6 min. Po zobojętniniu oznzno poziom ukrów rdukująyh mtodą Millr z użyim kwsu 3,5-dwunitrosliylowgo. Wyniki. Przprowdzon bdni wykzły, ż stbilność hmizn inuliny w środowisku kwśnym, w ph 4, zmnijszył się wrz z wzrostm tmprtury i zsu ogrzwni. W środowisku obojętnym i zsdowym inulin jst stbiln nizlżni od ph, tmprtury i zsu ogrzwni. Wnioski. Zstosowni inuliny w żywnośi moż być ogrnizon w produkth kwśnyh i poddwnyh ogrzwniu w tmprturh powyżj 6 C, w produkth o ph 5, nwt podlgjąyh obrób trmiznj do 1 C, ni zhodzi dgrdj tgo fruktnu. Słow kluzow: inulin, hydroliz, tmprtur, odzyn środowisk Rivd Przyjęto: Aptd for print Zkptowno do druku: For ittion Do ytowni: Glibowski P., Bukowsk A., 211. Th fft of ph, tmprtur nd hting tim on inulin hmil stbility. At Si. Pol., Thnol. Alimnt. 1(2),