RHEOLOGICAL PROPERTIES OF GLUTEN OBTAINED FROM POLISH WHEAT CULTIVARS

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1 1221 Bulgrin Journl of Agriculturl Science, 20 (No 5) 2014, Agriculturl Acdemy RHEOLOGICAL PROPERTIES OF GLUTEN OBTAINED FROM POLISH WHEAT CULTIVARS M. WESOŁOWSKA-TROJANOWSKA 1, M. TOMCZYNSKA-MLEKO 2, J. MAZURKIEWICZ 1, C. KWIATKOWSKI 3, K. KOWALCZYK 2, B. SOŁOWIEJ 1 nd S. MLEKO 1 * 1 University of Life Sciences, Deprtment of Biotechnology, Humn Nutrition nd Food Commodity Science, Lublin, Polnd 2 University of Life Sciences, Institute of Plnt Genetics, Breeding nd Biotechnology, Lublin, Polnd 3 University of Life Sciences, Deprtment of Herbology nd Plnt Cultivtion Techniques, Lublin, Polnd Abstrct WESOŁOWSKA-TROJANOWSKA, M., M. TOMCZYNSKA-MLEKO, J. MAZURKIEWICZ, C. KWIATKOWSKI, K. KOWALCZYK, B. SOŁOWIEJ nd S. MLEKO, Rheologicl properties of gluten obtined from polish whet cultivrs. Bulg. J. Agric. Sci., 20: The im of the study ws to investigte the rheologicl properties of gluten obtined from severl Polish whet cultivrs hrvested in 2010, 2011 nd Gluten ws seprted nd its elsticity nd spredbility were evluted. The following rheologicl methods were used: unixil extension using texture nlyser, ultrsound viscosity mesurements nd smll mplitude oscilltory sher mesurements. The protein content vried between 14.24% nd 11.74%. There were significnt differences in rheologicl properties of gluten obtined from the sme whet cultivrs t different hrvest yer. Gluten behved s n elstic mteril similr to prticulte gel with tendency for decrese in elstic component in comprison to viscous component t higher frequencies, which could suggest breking of some bonds. There ws liner correltion between ultrsound mesured viscosity nd mximum extensionl force, nd between ultrsound mesured viscosity nd storge modulus. All fundmentl rheologicl methods used for gluten investigtion gve results with n greement with bsic gluten elsticity mesurements performed ccording to Polish Stndrd method. Smples with better elsticity hd higher viscosity, mximum extension force nd storge modulus. Fundmentl rheologicl methods cn give better knowledge of the viscoelstic behvior of gluten, which cn improve dough qulity control. Key words: gluten, protein, rheology, texture, whet Introduction Whet is currently the most importnt humn food grin in the world. It rnks second fter mize, which is the first in totl production s cerel crop. Only in the Europen Union whet production in 2010/11 reched 650 million tones (Michlsk-Klimczk, 2011). Whet is n unique grin, becuse of the specil properties of its flour. The unique viscoelstic properties of the whet flour come primrily from the gluten-forming storge proteins. Gluten proteins re found in the endosperm of the mture whet grin. They re lrgely insoluble in wter or dilute slt solutions nd re composed of monomeric glidins nd polymeric (extrctble nd unextrctble) glutenins (Goesert et l., 2005). Gluten cn be defined s the viscoelstic residue remining fter strch grnules nd wter-soluble constituents re wshed out from the dough. It contins 75 85% protein nd 5 10% lipids in dry mss (Wieser, 2007). Gluten is responsible for physicl properties of dough nd its qulity is usully chrcterized by the degree of extensibility nd elsticity (Juric et l., 2001). Considering the frequently implementtion of oxidtive improvers in the bkery industry, whet cultivrs with stronger gluten should be used. Ltely there is trend to use gluten to nonfood pplictions (cosmetic nd hir products, detergents, *Corresponding uthor: dirywhey@tlen.pl

2 1222 M. Wesołowsk-Trojnowsk, M. Tomczynsk-Mleko, J. Mzurkiewicz, C. Kwitkowski, K. Kowlczyk, B. Sołowiej nd S. Mleko rubber, nd polymer products). Obtined new biodegrdble, low cost nd non-toxic mterils cn be n lterntive for synthetic polymers (Lgrin et l., 2010). Gluten is complex system nd its viscoelstic behviour is not yet fully understood. Better knowledge of the viscoelstic properties of gluten is necessry for dough qulity control to improve its wter bsorption cpcity, cohesivity, viscosity nd elsticity. Mny empiricl mesurements of the rheologicl properties of gluten were used with such pprt s frinogrph, mixogrph, extensigrph, lveogrph, mylogrph or texturometer. Most of the methods were invented for industril pplictions, s they re esy to perform in fctory conditions. Obtined dt re usully used for dough processing nd qulity control. There is still not mny reserch done using fundmentl rheologicl methods nd finding existing correltions between mesured rheologicl properties. Gluten rheologicl properties cn be ffected by some fctors such s whet vriety, crop loction, temperture, rinfll, soil fertility nd hrvest yer (Stoev nd Ivnov, 2009b; Delibltov nd Kirchev, 2010). Stoev nd Ivnov (2009) noted, tht the genotype differences with regrd to sedimenttion nd wet gluten were mrkedly dependent on the yer, while the vritions of phrinogrphic vlues nd bred lof depended more on fertiliztion. They concluded tht the gronomy prctices ffect the vilbility nd uptke of nutrients, nd cuses increse of yield nd suppression of sufficient gluten ccumultion in the grin. Atnsov et l. (2010) observed, tht the vrieties with highest qulity ccumulted lowest gluten in grin, even in comprison to medium nd low-qulity whets. Storge of the grin cn deteriorte properties of gluten by free rdicl genertion/oxidtion nd non-enzymtic glycosyltion, which cn led to frgmenttion or cross-linking of proteins, lipids nd sugrs (McDonld, 1999). The im of this study ws to investigte the rheologicl properties of gluten obtined from severl Polish whet cultivrs hrvested in 2010, 2011 nd Mteril nd Methods A field experiment in growing spring whet ws crried out in the period t the Czesłwice Experimentl Frm, belonging to the University of Life Sciences in Lublin (Polnd), using split-block design with 3 replictions, in 27 m 2 plots. The study included spring whet cultivrs Monsun hrvested in 2010 (M10), 2011 (M11) nd 2012 (M12); Korynt hrvested in 2010 (K10), 2011 (K11) nd 2012 (K12); Tyblt hrvested in 2010 (T10), 2011 (T11) nd 2012 (T12) nd Zdr hrvested in 2010 (Z10), 2011 (Z11) nd 2012 (Z12). After hrvest, the grin ws brought to the sme moisture content 14%. The grin ws stored t controlled conditions in grnry in piles, on neutrl substrte t temperture rnge of o C for 3, 15 or 27 months. During storge, the whet grin ws protected from the direct ction of light (sunlight, rtificil illumintion) by mens of specil roller blinds s well s it ws erted (stirred) from time to time, thus preventing it s overheting. Protein concentrtion in the grin ws determined using Perten infrred nlyzer nd grin moisture ws mesured using the grvimetric method. Before milling, grin smples were clened by lbortory clener-seprtor Model SZD (ZBPP, Polnd). To obtin flour, before milling, 1000 g whet smples were tempered t 15% moisture t 22 o C for 24 h nd milled with n dpted lbortory mill (QC109/2, Hungry) using 0.8 mm sieve. Moisture content of the flour ws determined by oven drying t 130 C for 1 h by the AACC method 44-15A (AACC, 2000). Gluten seprtion, elsticity nd spredbility To obtin gluten pproximtely 50 g of the flour ws trnsferred into mortr, pproximtely 25cm ³ of wter t C ws dded nd the mixture ws kneded until it did not dhere to the wlls. The bll of dough ws formed nd immersed in wrm wter for bout 10 min. nd kneded with fingers to seprte the strch. Spredbility nd elsticity were determined by Polish Norm (PN-77/A , 1977). Spredbility ws mesured s the increse in dimeter of the 5 g gluten bll plced in n oven t 30 C for 60 min. Elsticity ws expressed s permnent elongtion in mm fter return of 20 mm cylinder mde of 5 g of gluten nd extended to 50 mm. Elsticity ws lso expressed by 4-point scle: (I o permnent elongtion 0-10 mm, II o permnent elongtion mm, III o permnent elongtion mm, IV o breking before 50 mm extension. Unixil extension Gluten cylinders were fixed between two clmps 30 mm prt using the TA-XT2i Texture Anlyzer (Stble Micro Systems, Godlming, UK). Before extension test, the gluten cylinder dimensions were 50 x 13 mm. The cylinders were extended for 50 mm with 1 mm/s speed. Six extensions were performed for ech gluten smple. Ultrsound viscosity Viscosity x density in mps x g/cm 3 of the gluten smples ws mesured using Unipn type 505 ultrsound viscometer (UNIPAN, Wrsw, Polnd). Before ech mesurement, ultrsound signl level ws checked. Mesuring probe of the mgnetostrictive vibrtor ws plced entirely in the gluten

3 Rheologicl Properties of Gluten Obtined from Polish Whet Cultivrs 1223 smple. Induced ultrsound wves were dmped by tested mteril nd the results were displyed s the product of viscosity nd density. All mesurements were performed in six replictions. Smll mplitude oscilltory sher mesurements Dynmic oscilltory mesurements were performed using RS300 (ThermoHke, Krlsruhe, Germny) rheometer with serrted prllel steel plte geometry (35 mm dimeter) to limit the potentility of sliding effects. Gluten smples (35 mm dimeter nd 3 mm thick) were nlyzed by strin nd frequency sweep. The temperture for ll mesurements ws 22 o C. For strin sweeps frequency of 0.1 Hz ws used. For frequency sweep 5% strin ws used, which ws in liner viscoelstic region. Sttisticl nlysis of results (stndrd devition nd nlysis of vrince) ws performed using the sttisticl progrm Sttistic 5.0 PL (SttSoft Polsk, Wrsw, Polnd). The significnce of differences between mens ws determined using the Tukey s test t confidence level of p 0.05 bsed on the lest significnt difference. Results nd Discussion Figure 1 shows wter content in grin of different cultivrs hrvested in different yers nd stored. Besides two cultivrs hrvested in 2012, there were no sttisticlly significnt differences in grin wter content. It shows tht the grin ws stored in proper conditions, which did not trigger such negtive phenomenon s e.g. overheting. There were no sttisticlly significnt differences in grin totl protein content (Figure 2). Only in cse of cultivr Korynt higher protein content in 2012 yer grin ws noted. This cultivr showed the highest protein content compred to other cultivrs included in the study. The protein content vried between 14.24% nd 11.74%. Strelec et l. (2010) found, tht there were no significnt chnges in totl protein content in whet seeds during one yer storge under different storge conditions, however chnges in protein chemicl properties were observed. Tble 1 presents bsic gluten chrcteristics (spredbility nd elsticity) mesured ccording to Polish Stndrd methods (PN-77/A , 1977). Spredbility up to 10 mm meets gluten qulity requirements nd in most cses such vlue ws mesured. Generlly it ws observed, tht gluten with lower spredbility ws chrcterized by higher elsticity (I o ). Gluten with higher permnent elongtion fter extension spred more esily stying in n oven t 30 C for 60 min. Gluten smples were subjected to unixil tensile test, which is one of the oldest nd most widely used test methods to mesure whet dough. Tensile tests usully produce n p- Tble 1 Flour moisture content, gluten spredbility nd elsticity Smple Flour moisture Gluten Gluten content, % spredbility, elsticity ( o ), mm mm K II (10 mm) K I (6 mm) K I (6 mm) M I (5 mm) M I (7 mm) M I (5 mm) T I (5 mm) T I (5 mm) T II (10 mm) Z II (11 mm) Z I (6 mm) Z II (12 mm) Grin moisture content, % 14.4 b b K10 K11 K12 M10M11 M12 T10 T11 T12 Z10 Z11 Z12 Fig. 1. Grin moisture content Totl protein content, % 14.5 b K10 K11 K12 M10 M11 M12 T10 T11 T12 Z10 Z11 Z12 Fig. 2. Grin totl protein content

4 1224 M. Wesołowsk-Trojnowsk, M. Tomczynsk-Mleko, J. Mzurkiewicz, C. Kwitkowski, K. Kowlczyk, B. Sołowiej nd S. Mleko proximtely uniform extension of smple providing necking does not occur (Dobrszczyk nd Morgenstern, 2003). Figure 3 shows extension curves obtined for whet cultivr Tyblt. In ll cses strin hrdening ws observed. For the smple T10 pek ws noted t the breking point with smll strin hrdening just before smple frcture. Usully strin hrdening ws observed fter 30 s of extension. Studies hve shown tht the strin hrdening properties exhibited during elongtionl mesurements of different flours relte to the bking performnce of those flours nd re requirement of gs retension (vn Vliet et l., 1992). Uthykumrn et l. (2002) showed tht gluten dough possessed much lrger elongtionl viscosities thn flour. Furthermore, pure gluten doughs lso possessed greter elongtionl viscosity thn glutenstrch doughs, whose elongtionl viscosity decresed with incresing proportion of strch. Dobrszczyk nd Morgenstern (2003) observed tht the stress-strin curves showed considerble strin hrdening, nd strin nd stress t rupture ws considerbly less for poor qulity flours thn good qulity flours. Nicols et l. (2003) suggested tht the increse in stress t frcture t extension reflects tht more entnglements were formed between gluten strnds. Mximum extension force differed for different cultivrs nd hrvest yers (Tble 2). For cultivr Zdr no significnt chnges in mximum extension force ws found. Mximum extension force is ssocited with extensive hydrogen bonding both within nd between high moleculr weight protein subunits in ddition to entropic nd energetic contributions (Tthm et l., 2008). Incresed strin hrdening ws ttributed to entnglement of long-chin molecules during extensionl flow, wheres in simple sher they remin coiled nd cn slip pst ech other, giving rise to observed sher thinning t higher strins (Cogswell, 1981). Bonding between gluten protein molecules influences its viscoelstic properties. Gluten is treted s good mteril for fundmentl rheologicl chrcteriztion, s the liner region of its viscoelstic behvior is extended up to 10%, wheres the linerity limit of dough is extremely low (0.2%) (Lefebvre et l., 2003). In our reserch liner viscoelstic domin ws between 5.76% nd 8.97% (dt not shown). Figure 4 shows frequency sweeps for gluten smples obtined from cultivr Tyblt. Gluten behved s n elstic mteril with storge moduli vlues 2-4 times higher thn loss moduli. Gluten should be viewed s kind of colloidl or prticulte gel, network formed by the ggregtion of prticles stuck together by hydrogen bonds nd hydrophobic interctions (Lefebvre et l., 2003). There ws n increse in storge nd loss moduli with frequency, but Tble 2 Rheologicl properties of gluten Viscosity x Smple density, mps x g/cm 3 Mximum extension force, N Storge modulus t 10 Hz, P K (12) * 0.20 (0.01) 1810 (23) K (17) b 0.25 (0.01) b 2421 (44) b K (24) b 0.27 (0.02) b 2403 (11) b M (12) 0.19 (0.03) 1942 (54) M (21) c 0.32 (0.07) c 2850 (122) c M (15) b 0.21 (0.01) 2276 (56) b T (23) c 0.30 (0.02) c 2722 (131) c T (11) c 0.26 (0.01) b 2435 (121) b T (29) b 0.20 (0.01) 1987 (70) Z (9) 0.17 (0.01) 1886 (18) Z (13) b 0.20 (0.02) 2305 (54) b Z (13) 0.17 (0.01) 1882 (39) * Mens within column followed by vrious letter (-c) re significntly different t (P = 0.05) Extensionl force, N T10 T11 T Time, s Fig. 3. Extensionl force curves for Tyblt cultivr gluten G', G" (P) G' T10 G'' T10 G' T11 G'' T11 G' T12 G'' T Frequency, Hz Fig. 4. Oscilltory frequency sweeps of gluten obtined from Tyblt cultivr

5 Rheologicl Properties of Gluten Obtined from Polish Whet Cultivrs 1225 tngent delt incresed (Figure 5). Higher frequency llowed more energy into the smple nd probbly some bonds between protein molecules broke, s decrese in elstic component in comprison to viscous component ws observed. It is in greement with strin wekening observed t initil stge of gluten extension (Figure 3). Sntos et l. (2005) lso noted decrese in the loss tngent vlues t higher frequencies. There were differences in storge modulus mesured t 10 Hz for different cultivrs nd hrvest yers (storge time). Modenes et l. (2009) obtined results indicting tht during 5 months storge period of whet grin the gluten force nd flling number did not chnge. Edwrds et l. (2003) noticed tht the rheologicl properties of whet dough were influenced gretly not only by cultivr genotype but lso by the environmentl conditions fced by the plnts during grin ripening. Gluten isolted from stronger bred whet cultivrs hs exhibited higher storge modulus nd lower loss tngent thn gluten isolted from wek whet cultivrs. In our reserch whet ws hrvested t different yers nd for the sme cultivr other fctors thn storge time could ffect the rheologicl properties of gluten. Gluten viscosity ws mesured using n ultrsound device. Mesuring mgnetostrictive vibrtor ws plced in the gluten smple nd ultrsound wves were dmped. The results were displyed s the product of viscosity nd density nd re presented in Tble 2. This method ws not previously used for mesurements of the rheologicl properties of gluten. Product of dynmic viscosity nd density mesured using ultrsounds ws correlted with other rheologicl mesurements: mximum extensionl force nd storge modulus G mesured t 10 Hz. Figure 6 presents liner correltion between ultrsound mesured viscosity nd mximum extensionl force with R 2 = Gluten smples with higher product of viscosity nd density rected with greter resistnce to tensile forces, producing higher vlues of extensionl force. Similrly gluten chrcterized by higher vlues of the product of viscosity nd density were more elstic s strong liner correltion (R 2 = 0.89) ws noted between viscosity nd storge modulus (Figure 7). Both methods re non-destructive. In oscilltory mesurements pplied stress does not ffect the rheologicl chrcteristics of the test mteril, s the mesurements re performed in the liner viscoelstic region. Assessing viscoelstic properties of whet flour dough nd gluten cn be very significnt becuse they ffect the dough hndling behvior during processing nd influence the interctions mong dough components (Updhyy et l., 2012). All fundmentl rheologicl methods used for gluten investigtion gve results with n greement with bsic gluten elsticity mesurements performed ccording to Polish Stndrd method (Tble 1). Smples with better elsticity hd higher viscosity, mximum extension force nd storge modulus. Dynmic viscosity x density, mps x g/cm y = 1851x R² = Mximum extensionl force, N Fig. 6. Correltion between mximum extensionl force nd product of dynmic viscosity nd density Tn delt T10 T11 T Frequency, Hz Fig. 5. Chnges of tngent delt with oscilltory frequency for gluten obtined from Tyblt cultivr Storge modulus t 10 Hz, P y = x R² = Dynmic viscosity x density, mps x g/cm 3 Fig. 7. Correltion between product of dynmic viscosity nd density nd storge modulus mesured t 10 Hz

6 1226 M. Wesołowsk-Trojnowsk, M. Tomczynsk-Mleko, J. Mzurkiewicz, C. Kwitkowski, K. Kowlczyk, B. Sołowiej nd S. Mleko Conclusion There were significnt differences in rheologicl properties of gluten obtined from the sme whet cultivrs t different hrvest yer. Probbly environmentl conditions fced by the plnts during grin ripening influenced the differences. Gluten behved s n elstic mteril similr to prticulte gel with tendency for decrese in elstic component in comprison to viscous component t higher frequencies, which could suggest breking of some bonds. Product of dynmic viscosity nd density mesured using ultrsounds ws correlted with other rheologicl mesurements: mximum extensionl force nd storge modulus There ws liner correltion between ultrsound mesured viscosity nd mximum extensionl force nd between ultrsound mesured viscosity nd storge modulus. All fundmentl rheologicl methods used for gluten investigtion gve results with n greement with bsic gluten elsticity mesurements performed ccording to Polish Stndrd method. Fundmentl rheologicl methods cn give better knowledge of the viscoelstic behvior of gluten, which cn improve dough qulity control. References AOAC Interntionl., Officil Methods of Anlysis of AOAC Interntionl, 17th ed. The Assocition, Githersburg, MD. Atnsov, D., N. Tsenov, I. Stoev nd I. Todorov, Performnce of Bulgrin winter whet vrieties for min end-use qulity prmeters under different environments. Bulgrin Journl of Agriculturl Science, 16 (1): Cogswell, F. N., Polymer melt rheology. George Godwin Ltd, London: Delibltov, V. nd Hr. Kirchev, Grin yield nd qulity of bred whet vrieties under the groecologicl conditions of Dobroudj region. Bulgrin Journl of Agriculturl Science, 16 (1): Dobrszczyk, B. J. nd M.P. Morgenstern, Rheology nd the bredmking process. Journl of Cerel Science, 38: Edwrds, N. M., S. J. Mulvney, M. G. Scnlon, nd J. E. Dexter, Role of gluten nd its components in determining durum semolin dough viscoelstic properties. Cerel Chemistry, 80: Goesert, H., K. Brijs, W. S. Ververbeke, C. M. Courtin, K. Gebruers nd J. A. Delcour, Whet flour constituents: how they impct bred qulity, nd how to impct their functionlity. Trends in Food Science & Technology, 16: Juric, D., D. Krlovic, D. Tusk, B. Petrovic, nd J. Dugum, Gluten s stndrd of whet flour qulity. Food Technology nd Biotechnology, 39: Lgrin, B., B. Goderis, K. Brijs nd J. A. Delcour, Moleculr bsis of processing whet gluten towrd biobsed mterils. Biomcromolecules, 11: Lefebvre, J., A. Prusk-Kędzior, Z. Kędzior, nd L. Lvennt, A phenomenologicl nlysis of whet gluten viscoelstic response in retrdtion nd in dynmic experiments over lrge time scle. Journl of Cerel Science, 38: McDonld, M. B, Seed deteriortion: physiology, repir nd ssessment. Seed Science nd Technology, 27: Michlsk-Klimczk, B, Widomości zbożowe; ze świt. Świt Zbóż, 16: Modenes, A. N., A. M. d Silv nd D. E. G. Trigueros, Rheologicl properties evlution of stored whet. Cienci e Tecnologi de Alimentos, 29: Nicols, Y., R. J. M. Smit, H. vn Alst, F. J. Esselink, P. L. Weegels nd W. G. M. Agterof, Effect of storge time nd temperture on rheologicl nd microstructurl properties of gluten. Cerel Chemistry, 80: PN-77/A-74041, Zirno zbóż i przetwory zbożowe - Ozncznie ilości i jkości glutenu. Polski Komitet Normlizcyjny, Wrsw, Polnd. Sntos., D. M. J., S. R. Monteiro nd J. A. L. d Silv, Smll strin viscoelstic behviour of whet gluten - pentosn mixtures. Europen Food Reserch nd Technology, 221: Stoev, I. nd A. Ivnov, Correltion between the bredmking properties of common winter whet vrieties nd some gronomicl fctors. Bulgrin Journl of Agriculturl Science, 15 (4): Stoev, I. nd A. Ivnov, 2009b. Interction of the technologicl properties of common winter whet vrieties with some gronomy fctors. Bulgrin Journl of Agriculturl Science, 15 (5): Strelec, I., D. Kocev Komlenić, V. Jurković, Z. Jurković nd Ż. Ugrćić-Hrdi, Qulity prmeter chnges in whet vrieties during storge t four different storge conditions. Agriculture Conspectus Scientificus, 75: Tthm, A. S. nd P. R. Shewry, Rubber elsticity nd whet gluten proteins. In: Food Mterils Science. Principles nd Prctice. Springer, New York: pp Updhyy, R., D. Ghosl nd A. Mehr, Chrcteriztion of bred dough: Rheologicl properties nd microstructure. Journl of Food Engineering, 109: Uthykumrn, S., M. Newberry, N. Phn-Thien nd R. Tnner, Smll nd lrge strin rheology of whet gluten. Rheologic Act, 41: vn Vliet, T., A. M. Jnssen, A. H. Bloksm nd P. Wlstr, Strin hrdening of dough s requirement for gs retention. Journl of Texture Studies, 23: Wieser, H., Chemistry of gluten proteins. Food Microbiology, 24: Received Februry, 2, 2014; ccepted for printing September, 10, 2014.