Retrogradação de geis de amido de milho : influencia de açucares, lipides e tipos de amido / Downgrading of Geis of cornstarch: the influence of sugars, lipids and types of starch

AUTOR(ES)
DATA DE PUBLICAÇÃO

1981

RESUMO

The retrogradation of: concentrated gels (starch-water) of 3 types of starch (extracted from 3 varieties of corn: Normal, Amylose Extender and Waxy) and the influence of 3 types of sugar (sucrose, maltose and glicose) and 4 types of triglycerides (TCM, Lauric, Babassu and Shortening) were investigated through the determination of the elastic modulus. Avrami s theory for polymer cristallization was utilized to study the kinetics of retrogradation.The cristallization of the gels, in alI cases studied, occurred through instantaneous nucleation followed by rod-like growth of crystals. Of the 3 starches studied, the Waxy starch presented the lowest values for the rate of retrogradation. The velocity of retrogradation was increased by the sugars and lowered by the lipids, such effects being proportional to the concentration. The action of the sugars appeared to be related to the size of the molecule and/or the number of hydroxyl groups of the sugar. Among the lipids, TCM was the most effective in retarding retrogradation. Studies with gels of Normal corn flour indicated a behavior similar to that of the starch gels with respect to the effect of sugars and lipids on retrogr A influência dos mesmos açúcares e lípides em sistemas diluídos de amido Normal-água, foi também estudada através do visco-amilógrafo Brabender. Os açúcares retardaram tanto a fase de gelatinização como a de resfriamento. Entretanto, os lípides não alteraram a fase de gelatinização mas modificaram a curva de resfriamento.adation. Moreover, the rate of retrogradation of these gels was increased by the addition of Normal and Amylose Extender starches and diminished by Waxy starch. The influence of the same sugars and lipids in dilute Normal starch-water systems was aIs o studied with a Brabender Amylograph. The sugars retarded the gelatinization as well as the cooling phase. On the other hand, the lipids did not affect the gelatinization but modified the cooling-curve

ASSUNTO(S)

maize starch amido milho açucar sugar

ACESSO AO ARTIGO

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