Proteína estruturadora de gelo em cultivares brasileiras de trigo e centeio: ocorrência, caracterização e aplicação em massas congeladas

• Ano de defesa: 2011
• Autor(a) principal: Vieira, Claudia Regina
• Orientador(a): Pirozi, Mônica Ribeiro
• Banca de defesa: Gloria, Maria Beatriz Abreu , Cruz, Renato Souza
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Ciência e Tecnologia de Alimentos
• Departamento: Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos
• País: BR
• Palavras-chave em Português: Trigo; Proteínas anticongelantes; Massas congeladas
• Palavras-chave em Inglês: Wheat; Antifreeze proteins; Frozen dough
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/437

Ice structuring protein (ISP) has shown a great potential to improve the quality of frozen foods. The extraction of these proteins from natural sources has been considered important. Twelve days after planting (germination period), winter (IPR 84 and CD 104) and spring (BRS Guabiju, Ônix and LD 062212) wheat varieties, and rye (IPR 89), grew for seven weeks under natural (green house, no temperature, light or humidity control) and cold conditions (0-3 ºC; 80 % RU, light conditions of 1 400 or 2 000 LUX, with a photoperiod of 10/14h, day/night). After harvesting, the leaves were cut and mashed in Tris-HCl buffer, and the proteins were extracted by vacuum infiltrating (pH 7.4). The ISP extracts obtained were reported as non acclimated (NA) and cold acclimated (CA), respecting the conditions they grew, and analyzed according to its chemical composition. The presence of ISP in the extracts was detected by SDS-PAGE and the study of the morphology of ice crystals. The CA extracts were used in frozen dough to verify the cryoprotectant effect of the ISP. Fresh and frozen bread dough without adding the CA extracts were used to compare the dough behavior subjected to the following analysis: freeze-thaw tolerance (syneresis), identification and quantification of the dough polymeric proteins by SE-HPLC, and dough microstructure by scanning electron microscopy. Total solids content varied between 0.74 and 0.86 % and 0.92 and 1.70 % for the CA and NA extracts, respectively. Crude protein content varied between 51.69 and 60.69 % and 43.78 and 52.18 % for the CA and NA extracts, respectively. Interaction between cold acclimation and variety did not affected ash content of the samples, but it was observed a decrease in the ash content in the CA samples, which was related to a decrease in the mineral synthesis under cold acclimation. Results from SDS-PAGE showed very little or no protein bands in the NA extracts, while several bands, with molecular mass ranging from 14.4 to 97.0 kDa, were observed in all the CA extracts. Spring wheat varieties seemed less responsive to the cold acclimation than the winter ones, considering that fewer protein bands were observed in the gels. The winter wheat and rye varieties showed protein bands ranging from 14.4 to 66.0 kDa, while the bands on the spring varieties exhibited molecular mass ranging from 20.1 to 66.0 kDa. After characterizing the ISPs extract, research proceeded with three varieties BRS Guabiju, CD 104 and IPR 89, spring and winter wheats, and rye variety, respectively. The CA extracts of all three samples were effective in changing the morphology of ice crystals, originating preferably tetrahedral and hexagonal crystals, which were different from the round and plane shaped crystals developed in distilled water, Tris-HCl buffer, and NA extracts. Although not statistically different, there was a consistent trend in reducing the syneresis when ISPs extracts were added in the bread dough, especially after the third freeze-thaw cycle. The ISPs extracts from the wheat varieties BRS Guabiju and CD 104 did not affect the total polymeric protein (PPP) and unextractable polymeric protein (UPP) content of bread dough, but the rye variety (IRP 89) decrease the PPP and UPP content on frozen dough, in such way that these values were similar to those observed in fresh dough. The SEM images of frozen bread dough with and without the ISPs extracts showed the damages caused on the gluten matrix due to the freezing, when compared to the fresh dough. The dough microstructure study led to the conclusion that the ISPs extracts added to bread dough imparted higher preservation to the gluten matrix during freezing, thus posing a great potential to produce frozen dough that makes breads very similar to the fresh ones. These results could contribute to divulge the presence of these proteins in cereals cropped in Brazil, and to increase the interest for ISP extraction from these cereals, and their usage in frozen foods.