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Master of Science / Department of Grain Science and Industry / J.M. Faubion / The market for frozen goods is expanding and the frozen dough goods sector still has potential to expand its market. It is well known that deterioration in bread quality occurs during frozen dough/bread production. In addition, it is known that dough rheology influences bread quality. To prevent deterioration of bread quality, many additives have been used and researched. Combinations of oxidants (potassium bromate and ascorbic acid) are widely used worldwide. However, potassium bromate may be carcinogenic to humans, and it has been detected in bread after baking. Since it has been prohibited or strictly limited in many countries, many researchers have tried to find a replacement. Ascorbic acid is safe for human intake, and does not persist in bread. However, it is not as effective as potassium bromate. Possible replacements in frozen doughs include oxidant (ascorbic acid)-enzyme combinations. This study evaluated the effects of ascorbic acid-specific enzyme combinations as a replacement for the potassium bromate in frozen dough and related the effects to dough behavior (gluten network strength) as evaluated by dynamic oscillation rheometry. Bread quality was evaluated by test baking. Based on the results from fresh baking studies, potassium bromate can be replaced by an optimum level combination of ascorbic acid and hemicellulase/endo-xylanase. This combination clearly improved loaf volume, and crumb grain over both control and potassium bromate containing doughs. For frozen dough/bread production, the addition of all additives improved bread quality, but ascorbic acid and endo-xylanase containing dough resulted in higher volume, and better crumb structure than did dough containing potassium bromate. Dough rheology experiments show that rheology was affected by both the process and additives. Strain sweeps gave the information about dough stability. Both the additives and proofing improved dough stability. Dough behavior (gluten network strength) was assessed by frequency sweeps. Dough containing ascorbic acid and endoxylanase was most stable during frozen dough processing.

Doctor of Philosophy / Department of Grain Science and Industry / Hulya Dogan / Jon M. Faubion / The overall hypothesis underlying this study is that the nature and extent of bran interactions with the gluten protein matrix play a dominant role in both 'in-process' dough and final product quality of whole grain baked goods. Therefore, the purposeful manipulation of those interactions should be able to minimize adverse processing or product characteristics resulting from bran inclusion/presence. The approach we took was to study the effects of bran milled to different particle sizes on dough development during and after dough mixing using fundamental rheology combined with traditional cereal chemistry approaches and x-ray microtomography (XMT). The research outcomes were used to create a better picture of how the bran is effecting the dough development and to suggest strategies that allow for the control of that effect. Study-I focused on characterization of the chemical properties, empirical rheological properties and baking performance of flours and dough with different bran contents from different sources. The development of dough microstructure and the resulting crumb texture in the presence of different bran were studied using XMT. HRW and SW bran additions resulted in higher water absorptions (WA) irrespective of the flour type and bran source. Fine bran caused slightly higher WA followed by coarse and as is bran. Both HRW and SW bran decreased the dough stability of HRW flour, while it improved the stability of SW flour doughs. Macro and microstructure of baked products were significantly affected both bran type and addition level. HRW bran added to HRW flour resulted in 8-23% decrease in loaf volume while SW bran added at the same level caused 3-11% decrease. XMT indicated that bran decreased the total number of air cells significantly. SW flour resulted in harder crumb texture than that of HRW flour breads. Overall, SW bran had less detrimental effects on mixing and baking performance of HRW flour. Study-II focused on specific bran particle size and composition on small and large deformation behavior of strong and weak flour doughs. Small deformation behavior was characterized using frequency and temperature sweep tests, while the large deformation behavior was studied using creep–recovery and uniaxial extensional testing. The results revealed that the rheological behavior of bran-enriched doughs depend on type of base flour, bran type, bran replacement level (0, 5, 10%), and the dough development protocol. Weak flour doughs benefited from inclusion of bran as inherently low peak height and stability of these doughs improved in the presence of bran. Temperature sweeps indicated a slight decrease in Gʹ and G" until around 55-60°C. In the same temperature range, presence of bran increased the moduli of composite four compared to that of the control flours. Creep compliance parameters indicated that both bran source and bran replacement had significant effect on maximum compliance (J[subscript max]) and elastic compliance (J[subscript e]). Finally, the bran type affected uniaxial extensional properties, maximum resistance (R[subscript max]) and elasticity (E), significantly independent from the type of base flour.

Nine 1B/1R translocated soft red winter wheat (SRWW) varieties and six non-1B/1R varieties from two crop years (1995-1996 and 1996-1997), grown in two Virginia locations (Warsaw and Blacksburg), were studied to evaluate the effects of the 1R rye chromosome on soft wheat flour quality and baking performance. The presence of the 1B/1R chromosomal translocation in wheat has been reported to provide disease resistance, but produce sticky doughs. The 1995-1996 and 1996-1997 SRWW flours were subjected to farinograph analysis and dough stickiness testing. Dough stickiness was determined by the Schwarzlaff-Shepherd Dough Stripping Method. Wheat samples from 1995-1996 were also analyzed for protein, ash, and moisture content, alkaline water retention capacity (AWRC), cookie diameter, tensile stress and strain, and by ¹³C nuclear magnetic resonance (¹³C-NMR) spectroscopy techniques. Significant (p = 0.0001) negative correlations were found between AWRC and cookie diameter of SRWWs grown in Warsaw and Blacksburg. Location was found to exert a significant effect on AWRC, cookie diameter and stickiness (p < 0.05). Farinograph data revealed that mixing characteristics of SRWW were affected significantly by variety, crop year and location (p < 0.05). In some cases the 1B/1R varieties had lower breakdown rates, longer departure times (DT) and lower mixing tolerance index (MTI), than their non-1B/1R counterparts. There was a significant difference (p = 0.0133) in the stickiness of 1B/1R and non-1B/1R samples from Blacksburg. However no such difference was found in the corresponding Warsaw samples (p = 0.9826), indicating that location exerted a significant effect on stickiness. Two flour samples exhibiting stickiness (one with and one without 1B/1R) and two non-sticky samples (one with and one without the 1B/1R) were fractionated into gluten, starch and water-solubles (WS) in order to determine if the sticky dough factor resided in the 1B/1R and / or non-1B/1R WS. The peel time of the interchanged samples, as in the case of 'Massey' flour combined with the WS from VA52-22, increased to 79 seconds from the 30 seconds originally observed in the Massey flour. However when gluten and starch fractions from a non-sticky, non-1B/1R sample,VA54-21, were mixed with WS from VA54-211 (sticky, 1B/1R), the peel time went from 18 in the original flour to 8 seconds. Tensile measurements showed dough stress was not significantly affected by the presence or absence of 1B/1R (p = 0.7057). However, dough strain was lower in 1B/1R translocated SRWWs (p = 0.0048). A ¹³C-NMR spectra failed to show differences amongst selected 1B/1R and non-1B/1R dough samples. Proton relaxation time (T1-rho-[H]) - a ¹³C-NMR technique, indicated that water did not exert a significant influence on the molecular dynamics within the dough samples of Massey (non-1B/1R), VA54-211 (1B/1R) and VA52-22 (1B/1R). However, the non-sticky, non-1B/1R sample (VA54-21) had a higher proton relaxation time at 62 ppm which may indicate the size of starch-protein particles in VA54-21 doughs were larger and less flexible than in the other three doughs. / Ph. D.

<p>Uprkos brojnim tradicionalnim reolo&scaron;kim metodama koje se već dugi niz godina koriste u proceni kvaliteta bra&scaron;na, postoji potreba za razvijanjem novih metoda, pomoću kojih bi se za kratko vreme i uz ograničenu količinu uzorka mogao uspe&scaron;no predvideti kvalitet bra&scaron;na i gotovog proizvoda. Na taj način selekcionerima bi bila omogućena procena tehnolo&scaron;kog kvaliteta linija p&scaron;enice čija je količina ograničena, dok bi se mlinarima obezbedio brz metod procene kvaliteta. Osnovni cilj istraživanja ove disertacije je ispitivanje mogućnosti primene novog reolo&scaron;kog uređaja glutopika u proceni kvaliteta bra&scaron;na i finalnog proizvoda &ndash; hleba, kao i mogućnost zamene tradicionalnih dugotrajnih metoda novom reolo&scaron;kom metodom.<br />Kako bi se ispitale i iskoristile mogućnosti reolo&scaron;kog uređaja glutopik za procenu kvaliteta p&scaron;eničnog bra&scaron;na definisani su optimalni uslovi merenja koji su podrazumevali upotrebu NaCl kao rastvarača i zadate parametre temperature (36 &deg;C), obrtne brzine me&scaron;ača (2700 rpm) i odnos bra&scaron;na i rastvarača (8,5/9,5). Zabeležen je veliki broj korelacija između parametara glutopika i empirijskih reolo&scaron;kih pokazatelja kvaliteta bra&scaron;na i testa. Takođe je utvrđena značajna korelacija između parametara glutopika i indikatora kvaliteta hleba u pogledu specifične zapremine i teksturnih karakteristika sredine hleba. Na osnovu parametara dobijenih merenjem na glutopiku definisane su granične vrednosti. Ustanovljeno je da se primenom glutopik metode može izvr&scaron;iti klasifikacija sorti p&scaron;enice prema kvalitetu. Pored toga, utvrđeno je da glutopik ima veliki potencijal da zameni alveograf u proceni kvaliteta bra&scaron;na u mlinarskoj i pekarskoj industriji. Reolo&scaron;ki parametri koji zavise od sadržaja proteina kao &scaron;to su moć upijanja vode i žilavost testa uspe&scaron;no se mogu predvideti pomoću parametara glutopika. Primenom glutopik metode postignuta je umerena predikcija specifične zapremine hleba, dok je postignuta veoma dobra predikcija teksturnih karakteristika sredine hleba.<br />U okviru ove disertacije je ispitan uticaj sorte i lokaliteta na tehnolo&scaron;ki kvalitet bra&scaron;na p&scaron;enice kako bi se utvrdilo koja od ispitivanih sorti ispoljava ujednačen kvalitet u različitim mikroklimatskim uslovima tokom dve proizvodne godine. U obe proizvodne godine pokazatelji kvaliteta bra&scaron;na su dominantno sortno određeni, pri čemu je zabeležen određeni uticaj mikroklimatskih faktora na lokalitetima gajenja. Odličan i najstabilniji kvalitet bra&scaron;na u 2011. godini je imala sorta Gordana koja je pokazala najveću adaptabilnost na mikroklimatske uslove. Apač je uniformno imao najlo&scaron;iji kvalitet duž svih ispitivanih lokaliteta. Domaće sorte su u 2012. godini imale promenljiv kvalitet u zavisnosti od lokaliteta gajenja. Hlebove proizvedene od domaćih p&scaron;eničnih sorti je karakterisala velika zapremina, rastresita struktura sredine sa izraženim velikim porama i mala čvrstoća sredine, dok je hleb proizveden od sorte Apač imao malu zapreminu, zbijenu strukturu sredine hleba sa velikim brojem malih pora kao posledicu velike čvrstoće. Dobra predikcija kvaliteta hleba od bra&scaron;na iz 2011. godine je postignuta primenom jednog reolo&scaron;kog pokazatelja kvaliteta, dok je za uspe&scaron;nu predikciju kvaliteta hleba od bra&scaron;na iz 2012. godine neophodno izvesti nekoliko različitih reolo&scaron;kih merenja.<br />Analizom tehnolo&scaron;kog kvaliteta bra&scaron;na p&scaron;enice različitih sorti gajenih na različitim lokalitetima iz tri proizvodne godine zabeležene su velike varijacije u kvalitetu bra&scaron;na i hleba na ispitivanim lokalitetima i u proizvodnim godinama, &scaron;to jasno ukazuje na značajan uticaj interakcija između sortimenta i uslova gajenja (lokaliteta i godina), kao i značaj ispitivanja ovih interakcija i razvoja strategija koje imaju za cilj smanjenje uticaja spolja&scaron;njih faktora na kvalitet p&scaron;enice.</p> / <p>Regardless the fact that numerous traditional rheological methods have been used for many years in the flour quality assessment, there is a need for developing new methods, which could, in a short time, and with a limited amount of sample, successfully predict the quality of flour and finished products. In this way, wheat breeders would be able to evaluate the technological quality of the wheat lines with a restricted sample quantity, while the millers would be provided with a quick method of the quality evaluation. The main goal of the research of this dissertation was to examine the possibility of using a new rheological device GlutoPeak in the quality evaluation of flour and final product &ndash; bread, as well as the possibility of replacing traditional time-consuming methods with a new rheological test.<br />In order to examine the possibility of using a GlutoPeak rheological device for the flour quality evaluation, the optimal measurement conditions were defined and included the use of NaCl as a solvent, the rotational speed of the mixer (2700 rpm), temperature (36 &deg;C), the ratio of flour and solvent (8.5/9.5). Numerous correlations between GlutoPeak indices and empirical rheological parameters of dough behaviour were reported in this study. Significant correations were also observed between GlutoPeak parameters and bread specific volume and breadcrumb textural properties. The limit values were defined according to the GlutoPeak parameters values. Moreover, it was found that the GlutoPeak test could be used for wheat variety diferentiation according to the quality and has a great potential to replace Alveograph in the flour quality assessment in the milling and bakery industries. Parameters which depends on the protein content, such as, flour water absorption and dough tenacity, was successfully predicted by using parameters derived from GlutoPeak tester. A moderate prediction of loaf specific volume was achieved, while a very good prediction of breadcrumb textural characteristics was accomplished with the GlutoPeak parameters.<br />In addition, the influence of genotype and growing location on flour quality was examined in order to determine which of the tested varieties exhibited uniform quality accross different microclimatic conditions in two production years. It was revealed that in both production years flour quality indicators were predominantly influenced by genotype, with a certain influence of microclimate factors on the growing locations. Gordana variety showed excellent and uniform quality with the highest adaptability to microclimate conditions in year 2011. Apache variety showed uniformly poor quality across all tested locations. In year 2012 domestic varieties exhibited variable quality depending on the growing locations. Bread produced from domestic wheat varieties was characterized by a large volume, loose breadcrumb structure with pronounced large pores and low hardness, while the bread produced from Apache variety had a small volume, dense breadcrumb structure with a large number of small pores as a result of high breadcrumb hardness. The quality of bread produced from wheat flour from year 2011 was well predicted based on one rheological quality parameter. On the other hand, several different rheological measurements was performed to successfully predict the quality of bread produced from wheat flour from 2012 year.<br />By analyzing the technological quality of wheat flour of different varieties cultivated at different locations from three production years, large variations in the quality of flour and bread was recorded. The variations in flour and bread quality indicated the significant influence of interactions between the variety and growing conditions (locations and years), as well as the importance of examining these interactions and developing strategies aimed at reducing the impact of external factors on wheat quality.</p>

By-products of fruit, cereal and vegetable processing are often regarded as waste while they contain significant amounts of dietary fibre and phytochemicals that can positively contribute to the human diet when reused as food ingredient. The application of fibre from by-products in baked goods could increase the sustainability of the processing chain but is usually associated with changes in product characteristics, such as lower volume, denser structure and increased hardness. In the current study, the interactions of fibres from by-products and wheat macromolecules were analysed in muffins, starch slurries and wheat doughs. The three selected fibres differed significantly in their chemical composition and technofunctional properties. In muffins wheat flour replacement by apple fibre was assessed by rheological measurements of batter and determination of product characteristics. Water proportion adaption based on batter viscosity to create isoviscosity was evaluated as a promising method to develop muffins with satisfying characteristics, where a wheat flour replacement of 30 % is suggested. The addition of apple fibre influenced starch gelatinisation in muffins during baking as indicated by the results of pasting experiments and in vitro starch digestion. Starch slurries with apple and wheat fibre were analysed in pasting experiments. Soluble dietary fibre, mainly pectin, strongly influenced the pasting profile of wheat starch, in comparison to insoluble dietary fibre, that acted as an inert filler and did not interact with the starch. Wheat doughs with fibre from by-products were analysed for rheology, texture and microstructure. The gluten development was negatively influenced by the fibres, which resulted in less extensible doughs. Soluble dietary fibre resulted in increased dough stickiness and limited dough handling at high application levels. It can be reasoned that dough with 10% fibre from by-products would produce products with satisfying characteristics, whereas higher application levels cannot be recommended without using additives to increase the gluten strength. Fibres from by-products are suitable wheat flour replacers in bakery products, where the negative effects of the high water binding capacity of the fibre, can be partly balanced by water proportion adaption, especially in products were gluten development is not that dominating for product structure, like in muffins or cakes. / Nebenprodukte der Obst-, Getreide- und Gemüseverarbeitung werden oft als Abfall betrachtet, wobei sie signifikante Gehalte an Ballaststoffen und sekundären Pflanzeninhaltsstoffen aufweisen, und bei der Verwendung als Lebensmittelzutat positiv zur menschlichen Ernährung beitragen können. Die Anwendung von Fasern aus Nebenprodukten in Backwaren könnte die Nachhaltigkeit der Verarbeitungskette erhöhen, ist jedoch mit Änderungen der Produkteigenschaften verbunden, wie verringertes Volumen, dichtere Struktur und erhöhte Härte. In der vorliegenden Studie wurden die Wechselwirkungen von Fasern und Weizenmakromolekülen in Muffins, Stärkesuspensionen und Weizenteigen analysiert, wobei sich die drei ausgewählten Fasern in ihrer chemischen Zusammensetzung und ihren technofunktionellen Eigenschaften unterschieden. In Muffins wurde die Mehlsubstitution durch Apfelfaser anhand von Teigrheologie und Produkteigenschaften analysiert. Die Anpassung des Wassergehaltes basierend auf der Teigviskosität wurde als vielversprechende Methode zur Entwicklung von Muffins mit akzeptablen Eigenschaften bewertet, wodurch ein Mehlersatz von 30% möglich war. Die Zugabe von Apfelfasern beeinflusste die Stärkeverkleisterung in Muffins, wie durch die Ergebnisse von Verkleisterungsexperimenten und In vitro-Stärkeverdauung gezeigt wurde. Stärkesuspensionen mit Apfel- und Weizenfasern wurden auf ihr Verkleisterungsverhalten analysiert. Lösliche Ballaststoffe beeinflussten das Verkleisterungsprofil von Weizenstärke im Vergleich zu unlöslichen Ballaststoffen, die als inerter Füllstoff fungierten und nicht mit der Stärke in Wechselwirkung traten. Weizenteige mit Fasern wurden auf Rheologie, Textur und Mikrostruktur untersucht. Die Glutenentwicklung wurde durch die Fasern negativ beeinflusst, was zu weniger dehnbaren Teigen führte. Lösliche Ballaststoffe führten zu einer erhöhten Teigklebrigkeit. Weizenteig mit 10% Faser besitzt zufriedenstellenden Eigenschaften, während höhere Fasermengen nicht zu empfehlen sind, ohne Zusatzstoffe, um die Glutenfestigkeit zu erhöhen. Fasern aus Nebenprodukten sind geeignet als Mehlersatz in Backwaren, wobei die negativen Auswirkungen der hohen Wasserbindekapazität der Faser teilweise durch Wasseranpassung ausgeglichen werden können, insbesondere in Produkten, bei denen die Glutenentwicklung nicht die Produktstruktur dominiert, wie in Muffins oder Kuchen.