Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Bread flour quality, which is directly related bread quality, varies from time to time. It is therefore almost impossible to obtain bread with consistent quality without determining the flour's suitability for bread-making and the addition of bread improvers. Rheological tests such as the farinograph and the mixograph which are commonly used by bakeries to predict flour quality are empirical in nature which makes fundamental interpretation of the results difficult. The stress relaxation test, a more fundamental rheological test, was used in combination with the mixograph to determine if the stress relaxation test can provide additional information to the mixograph on prediction of the effect of ascorbic acid and DATEM on bread-making quality of three different flour samples. In this test, an optimally developed ball of dough was compressed between parallel plates of a TA-XT2 texture analyser. The 20 g dough was compressed to a load of 1.5 N and thereafter allowed to relax at constant deformation. The relaxation time (RT) was recorded as time taken for the compression force to decay to a force of 0.65 N. Longer RT indicated better flour quality. RT was compared with the mixograph peak time and peak height as predictors of the effect of ascorbic acid and DATEM on bread quality. Test bakes were carried out, and concentrations of ascorbic acid and DATEM were varied as in the stress relaxation test and the mixograph test. At the various stages of the baking process several dough and bread properties were assessed subjectively and scored according to a standardised scoring system. The mixograph was successful in characterising untreated flours in terms of bread-making quality and the stress relaxation test did not provide additional information in this regard. The mixograph was better able to predict the effect of improvers on the stronger Lelie while the stress relaxation test was better at predicting improver effect (especially of DATEM) on the weaker flours, Tiger and Silver Queen. The mixograph predicted the improving effect of DATEM on Tiger and Silver Queen up to a peak, followed by no further improvement. The stress relaxation test predicted improvement beyond the peak, and this continued improvement was observed in the test bake and strong correlation (p<O.05) was found between effect of DATEM on RTs and these important test bake parameters: baking height, loaf volume, drop baking height and the bread score. In addition to information on mixing properties provided by the mixograph, RT seemed to be predicting dough's stability, related to its gas-retaining properties. This stability which can be enhanced by DATEM may be related to both the extensibility of dough's gluten matrix and the stability of the liquid film surrounding the gluten matrix. / Dissertation (MSc (Agric) Food Science and Technology)--University of Pretoria, 2005. / Food Science / unrestricted

<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>

High pre-harvest rainfall in 2006 caused significant pre-harvest sprouting (PHS) and weathering throughout the mid-Atlantic soft red winter wheat (SRWW) (Triticum aestivum L.) growing region. Sprouting and weathering caused decreased flour quality due to lowered dough viscosity and decreased ability to withstand mixing and processing for baked goods. Due to its decreased quality, severely sprouted grain is sold for feed, at a lower price per bushel. Pre-harvest sprouting negatively affects the chain of production from the field to baking operations. The purpose of this research was to evaluate the inherent dormancy and PHS resistance, of current SRWW cultivars and to assess the relationship between falling number and flour quality after grain weathering. Employing a weighted germination index (WGI), a large range in dormancy was observed across SRWW cultivars and seed production. Artificial weathering tests confirmed the use of WGI as a tool for screening for dormancy of SRWW cultivars. The WGI consistently identified cultivars with significantly higher or lower inherent dormancy. "Coker 9553" was highly dormant and resistant to PHS. This cultivar maintained an average falling number of 300 seconds even after receiving an average of 215 mm of rainfall, while the mean falling number for all SRWW cultivars after this amount of weathering was 131 seconds. After only moderate weathering, nine of 15 SRWW cultivars in the study exhibited severe sprouting, demonstrating the need for increased PHS resistance in SRWW wheat. Pre-harvest sprouting resistance groupings, based on average 2008 cultivar falling number were accurately predicted by WGI at both 10 (R2=0.79) and 30°C (R2=0.72) No consistent relationship was observed between head angle, glume tenacity or awn length and PHS resistance. Water absorption, dough stability, farinograph arrival and departure times, peak, and 20-minute drop were measured from grain samples with varying degrees of weathering. All parameters were negatively affected by weathering in 2008. Flour quality parameters were more affected by genotype than falling number suggesting that falling number should not be used as the sole indicator of flour quality after grain weathering. It is clear that there are vast differences in dormancy levels and PHS resistance among SRWW cultivars and stronger dormancy and higher resistance to PHS does not automatically ensure higher quality flour. / Master of Science

Made available in DSpace on 2016-12-08T16:44:45Z (GMT). No. of bitstreams: 1 PGPV13MA127.pdf: 511615 bytes, checksum: 8ea8d8706c74bcaf1ec6542c4f4ef048 (MD5) Previous issue date: 2013-07-25 / The lack of incentive to production, small crop area and low grain yield are the main factors to annual deficit in Brazilian wheat production. The production can be increased by the area and/or grain yield. The use of nitrogen in wheat can to increase grain yield, but the N excess associated to the weather (rain and wind) can lead the occurrence of lodging and negatively affect the yield and grain quality. Thus, the aim of this study was to evaluate the effects of nitrogen application during the grain filling, associated with the use of plant growth retardants on the characteristics of plant height, yield and industrial quality of wheat cultivar Mirante. The experiment was carried out under field conditions in the experimental area of the Santa Catarina State University - UDESC in Lages SC, in the 2011 and 2012 growing seasons. The experimental design was a randomized block with four replications. For plant height and yield were used two times of application of nitrogen (at vegetative and vegetative plus reproductive stages) associated with six- growth retardants. For industrial quality evaluations the nitrogen topdressing was used in two application times (at vegetative and vegetative plus reproductive stages) associated with etil-trinexapac retardant. In both experiments the retardants were applied in two doses (stages 31 and 32 first and second visible nodes in the main stem of the plant) plus the control. Treatments were: control (no retardant), mepiquat chloride (25 g a.i. ha-¹), chlorocoline chloride (25 g a.i. ha-¹), chlormequat chloride (25 g a.i. ha-¹), etil-trinexapac (100 g a.i. ha-¹), proexadione-Ca (110 g a.i. ha-¹) and ethephon (110 g a.i. ha-¹), which were applied by sprayer pressurized with CO2 at a rate equivalent to 200 L ha-¹. The use of growth retardant lead to shortest plant height, and the etil-trinexapac and proexadione-Ca were provided to lowest plant height. The use growth retardant plus nitrogen fertilization in the reproductive stage did not affect grain yield. The use of etil-trinexapac positively affected the tenacity, extensibility, extensibility and toughness over falling number. Applying N at reproductive stage of wheat led to an increase in sedimentation, extensibility, protein content, wet gluten, dry gluten and gluten strength in improving the industrial quality of wheat; however the magnitude of the response was dependent manner of the environmental conditions in each crop year / A falta de incentivo à produção, a pequena área cultivada e os baixos tetos produtivos são fatores que contribuem para o déficit anual na produção brasileira de trigo. O aumento da produção pode ser por aumento da área e/ou da produtividade de grãos. O uso de nitrogênio na cultura do trigo visa o aumento da produtividade, porém o excesso deste nutriente aliado ao clima (chuva e vento) pode favorecer a ocorrência de acamamento e diminuir o rendimento e a qualidade final dos grãos. Desta forma, o objetivo desse trabalho foi avaliar os efeitos da aplicação de nitrogênio em cobertura durante o estádio vegetativo e reprodutivo, associado ao uso prévio de redutores de crescimento sobre as características de altura de planta, produtividade e qualidade industrial do trigo, cultivar Mirante. O experimento foi conduzido em campo, na área experimental da Universidade do Estado de Santa Catarina - UDESC, em Lages SC, nos anos agrícolas 2011 e 2012. O delineamento experimental empregado foi o de blocos ao acaso, com quatro repetições. Para altura de plantas e produtividade foram utilizados dois diferentes momentos de aplicação de nitrogênio em cobertura (estádio vegetativo) e (estádio vegetativo+reprodutivo) associado ao uso prévio de seis redutores de crescimento. Para a qualidade industrial foi utilizado o nitrogênio em dois diferentes momentos de aplicação de nitrogênio em cobertura (estádio vegetativo) e (estádio vegetativo+reprodutivo) associado ao uso prévio do redutor de crescimento etil-trinexapac. Em ambos os experimento os redutores foram aplicados em duas doses (estádios 31 e 32 primeiro e segundo nós visíveis no colmo da planta) mais a testemunha. Os redutores utilizados foram: testemunha (sem redutor), cloreto de mepiquate (25 g i.a. ha-¹), cloreto de clormequate (25 g i.a. ha-¹), cloreto de clorocolina (25 g i.a. ha-¹), etil-trinexapac (100 g i.a. ha-¹), proexadione-Ca (110 g i.a. ha-¹) e o etefom (110 g i.a. ha-¹); os quais foram aplicados via pulverizador costal pressurizado com CO2, com uma vazão equivalente a 200 L ha-¹. O emprego dos redutores de crescimento reduziu a altura das plantas, sendo que o etil-trinexapac e o proexadione-Ca foram os que proporcionaram plantas de menor altura. O uso dos redutores de crescimento e da adubação nitrogenada no estádio vegetativo+reprodutivo não afetou o rendimento de grãos. O emprego do etil-trinexapac afetou positivamente a tenacidade, extensibilidade, relação tenacidade/extensibilidade e o número de queda. A aplicação de N na fase reprodutiva do trigo propiciou um aumento na extensibilidade, teor de proteína, glúten úmido, glúten seco e na força do glúten melhorando a qualidade industrial do trigo, entretanto a magnitude da resposta foi dependente do ano agrícola