Perfil protéico e qualidade de panificação em linhagens de trigo desenvolvidas para a região do cerrado brasileiro / Profile protein and quality of bakery in strains of wheat developed for the region of the Brazilian Cerrado

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The region of Cerrado constitutes important alternative in the expansion of Brazilian wheat area, considering the need of wheat supply for milling industries of the country and the expenses with this cereal import. Besides, there is the difficulty of alternatives of winter crops. Nonetheless, wheat cultivation in Cerrado and Minas Gerais State demands the development of new varieties, adapted to the specific soil and climate conditions, and with high technological quality. This work aims to identify glutenin subunits responsible for the technological quality in twenty-seven in-breeding wheat lines and two wheat cultivars, to examine the relationship between the electrophoresis results and size-exclusion high- performance liquid chromatography (SE-HPLC) parameters, and to identify the bread-making potential of the wheat material. The ultimate goal is to present to breeders potential micro-scale tests that could accurately estimate the technological quality of wheat in the early breeding stages of a new wheat cultivar. Wheat samples were studied for the composition of high molecular weight glutenin subunits (HMW- GS), through electrophoresis in SDS-PAGE and the molecular weight distribution of the polymeric proteins using SE-HPLC. Bread-making test was used to determine the technological quality of the samples, and to verify the correlation between electrophoresis and SE-HPLC data with bread-making quality parameters. Thirteen different HMW-GS, 1, 2 *, 7, 8, 9, 13, 16, 17, 18, 2, 5, 10 and 12, were identified in the samples studied. It was observed that breeding lines with the same progenitors exhibited different allelic combinations. The molecular weight distribution of wheat protein was determined by the following SE-HPLC data: percentage of polymeric protein in the total protein (PPP), percentage of unextractable polymeric protein (UPP), content of polymeric protein in the flour (PPF) and content of unextractable polymeric protein in the flour (UPPF). Breeding lines with greater UPP did not necessarily present greater PPP, evidence that the polymerization degree of the glutenin subunits does not depend on the total content of polymeric proteins. Breeding lines with greater UPP expressed subunits 5+10, and breeding lines with low value expressed the allelic pair 2+12, except for the Pioneer variety. It was suggested that chain terminators, which reduce glutenins polymerization, could be present in this variety. Subunits 2 *; 7, 8 and 9 (in their allelic combinations 7+8 and 7+9); and the pair 5+10 presented greater correlation with bread volume and total bread-making score (CG). Breeding lines with low bread- making quality expressed the subunits 2+12. Of all evaluated parameters, UPP presented higher positive correlation, of 0.94 and 0.69 with bread volume and CG, respectively. PPP showed low correlation with the bread volume (0.35), and no significative correlation with CG, demonstrating that only the larger molecular weight fractions of polymeric protein seem to be related with bread-making quality in the studied flours. The high correlation degree, mainly from UPP and Glu-1 score, with bread volume and CG indicates that those parameters can be successfully used to estimate the bread-making quality in wheat breeding programs, allowing that only the genetic material of better technological quality to be used in the development of new varieties.

ASSUNTO(S)

exclusão molecular tecnologia de alimentos glutenin glutenina electrophoresis sds-page eletroforese sds-page molecular exclusion

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