En aquesta Tesi Doctoral es va estudiar el potencial de varietats tradicionals de blat dur per a la millora de la qualitat i el valor agronòmic en base a una col•lecció de 172 accessions procedents de 21 països mediterranis. Com a referència es va utilitzar un conjunt de 20 varietats modernes representatives de la variabilitat cultivada a la zona. Els assaigs de camp es van dur a terme en secà durant tres anys a Gimenells (Lleida). Es va estudiar la variabilitat existent a la col•lecció per a les principals característiques agronòmiques i de qualitat, la presència d’estructures geogràfiques i l’efecte del clima prevalent als països d’origen de les varietats sobre llur comportament agronòmic. Es va analitzar la relació existent entre la força del gluten i la composició al•lèlica en cinc loci de glutenines d’alt (HMW) i baix (LMW) pes molecular i es van identificar noves fonts d’al•lels potencialment interessants per la millora de la qualitat. / En esta Tesis Doctoral se estudió el potencial de variedades tradicionales de trigo duro para la mejora de la calidad y el valor agronómico en base a una colección de 172 accesiones procedentes de 21 países mediterráneos. Como referencia se utilizó un conjunto de 20 variedades modernas representativas de la variabilidad cultivada en la zona. Los ensayos de campo se llevaron a cabo en secano durante tres años en Gimenells (Lérida). Se estudió la variabilidad existente en la colección para las principales características agronómicas y de calidad, la presencia de estructuras geográficas y el efecto del clima prevalente en los países de origen de las variedades sobre su comportamiento agronómico. Se analizó la relación existente entre la fuerza del gluten y la composición alélica en cinco loci de gluteninas de alto (HMW) y bajo (LMW) peso molecular y se identificaron nuevas fuentes de alelos potencialmente interesantes para la mejora de la calidad / A collection of 172 durum wheat landraces from 21 Mediterranean countries was assembled and used to examine their value for quality and field performance improvement in breeding programs. A set of 20 representative modern varieties were used for comparison. Field experiments were conducted during 3 years under rainfed conditions in northeastern Spain. The existing variability for the main quality and agronomic traits, the presence of geographic structures as well as the effect of the climate in the countries of origin on the agronomic performance were investigated. The relationship between gluten strength and the allelic composition at five glutenin loci was assessed, and donors of potentially novel alleles for quality improvement were identified.

Tortilla sales are projected to exceed 9.5 billion by 2014. However, currently no wheat cultivars have been identified that possess the intrinsic quality attributes needed for the production of optimum quality tortillas. Tortillas made with refined wheat flour low in dietary fiber (DF) are popular in the United States due to their sensory properties. This study explored the use of wheat lines (WL) possessing variations in high molecular weight glutenin allele sub-units (HMW-GS) for production of tortillas and also investigated the use of corn based resistant starches (RS), type II (RS2) and wheat based RS type IV (RS4) to increase DF in tortillas. Tortillas were made with 0-15 percent RS and 100 percent whole white wheat (WW). Flour protein profiles, dough, and tortilla properties were evaluated to determine the effects of the allelic variations and RS substitution on tortilla quality. Sensory properties of tortillas with RS were determined. Variations in HMW-GS composition significantly affected the protein quality and tortilla properties. Flour from WL possessing allelic combinations (2*, 17+18, 7, 2+12), (1, 17+18, 5+10), (2*, 17, 2+12) and (1, 2*, 17+18, 2+12) had 12.8-13.3 percent protein. These WL had extensible doughs and produced large diameter tortillas with superior (greater than or equal to 3.0) flexibility after 16 days compared to control. However, WL with (17+18 and 5+10) and (2*, 17+7, 5) produced extensible doughs, large, but less flexible, tortillas compared to control. WL with (2*,17+18,5+10) and (1,2*,7+9,5+10) produced smaller diameter tortillas, but with superior flexibility compared to control. RS2, WW, and cross-linked-pre-gelatinized RS4 (FiberRite) produced hard, less-extensible doughs and thinner tortillas compared to control, due to high water absorption. Cross-linked RS4 (Fibersym) dough and tortillas were comparable to control. 15 percent of RS2 and RS4 increase DF in control to 6 and 14 percent respectively, compare to control (2.8 percent DF). WW tortillas were less acceptable than control in appearance, flavor and texture, while tortillas with 15 percent Fibersym had higher overall acceptability than control. RS2 negatively affected dough machinability and tortilla shelf stability. However, 15 percent RS4 improved the DF in refined flour tortillas to meet FDA's "good source of fiber claim," without negatively affecting dough/tortilla quality.