Estudo reológico de sistemas gelatina/colágeno/amido para obtenção de géis e aplicação dietéticas de gelatina
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Data
2010-03-18
Autores
Marfil, Paulo Henrique Mariano [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O comportamento reológico de soluções aquosas de gelatina e colágeno hidrolisado (4 e 10 % de sólidos totais) e de gelatina e amido de milho modificado de forma ácida (AMMA) (10 % de sólidos totais) foi estudado através de testes dinâmicos oscilatórios em um reômetro de tensão controlada com geometria cone e placa (60 mm de diâmetro e distância de trabalho de 52 mm). Para todas as concentrações, o módulo de armazenamento, G`, aumentou com aumento da freqüência angular. Como esperado, os valores dos módulos correspondentes aos platôs aumentou com o aumento da concentração de gelatina e os valores de G` foram maiores nas soluções contendo amido. Os valores de G` e G`` aumentaram com a diminuição da temperatura. O colágeno hidrolisado não apresentou comportamento de gel. A substituição de 25 % de gelatina por amido de milho modificado resultou em valores similares de G` nas amostras contendo somente gelatina. Foi realizado um estudo de separação de fases nas suspensões aquosas de gelatina e AMMA através de microscopia laser confocal, sendo observado que os biopolímeros co-existem, sem separação de fases na amostra em que gelatina e AMMA representam, respectivamente, 37,5 % e 62,5 % dos sólidos totais. Em geral, os demais sistemas apresentaram separação de fases, sendo esta mais pronunciada à medida que as amostras foram ficando enriquecidas com gelatina ou amido. Também foi estudado o comportamento reológico por compressão e as propriedades colorimétricas de gomas de gelatina dietéticas enriquecidas com colágeno hidrolisado e preparadas à base de xarope de maltitol e xilitol. A análise dos parâmetros de textura e o estudo colorimétrico permitiram observar que não há efeitos significativos (p<0,05) na interação entre concentração de gelatina e colágeno hidrolisado quanto à dureza das amostras. Além disso, a maior concentração...
The rheological behavior of aqueous solutions of gelatin and hydrolyzed collagen (4 and 10 % total solids) or gelatin and acid modified corn starch (AMCS) (10 % total solids) was studied. A controlled stress rheometer fitted with a cone and plate geometry (60 mm, gap 52 mm) was used for the dynamic oscillatory shear tests. For all concentrations, the storage modulus increased with the increasing angular frequency. As expected, the modulus plateau values increased with gelatin concentration increasing and G` was higher in the solutions with modified corn starch. G` and G`` values attained the highest observed values at lower temperatures. Hydrolyzed collagen did not show gel formation ability. When 25 % of the gelatin content was substituted by AMCS, the observed values of G` were similar to those corresponding to pure gelatin suspensions. A phase separation study was carried out with gelatin and AMCS aqueous suspensions using confocal laser scanning microscopy. The results showed that the two biopolymers co-exist, without phase separation in a system containing 37,5 % of gelatin and 62,5 % of AMCS (based in a 10 wt% total solids). In general, the others systems showed phase separation, which was more intense with increasing gelatin/AMCS concentration. The rheological behavior in compression and the optical proprieties of diet gelatin gummy enriched with hydrolyzed collagen were also studied. The gummies were prepared with maltitol syrup and xilitol. The analysis of texture and opacity parameters showed that significant effects (p<0.05) were not observed in the interaction between the two factors with regard to samples hardness. High concentrations of gelatin and hydrolyzed collagen resulted in a high opacity. The rheological behavior in compression and the optical proprieties of gelatin/AMMA gels were also studied. When AMCS was introduced into gelatin gels, the system structure... (Complete abstract click electronic access below)
The rheological behavior of aqueous solutions of gelatin and hydrolyzed collagen (4 and 10 % total solids) or gelatin and acid modified corn starch (AMCS) (10 % total solids) was studied. A controlled stress rheometer fitted with a cone and plate geometry (60 mm, gap 52 mm) was used for the dynamic oscillatory shear tests. For all concentrations, the storage modulus increased with the increasing angular frequency. As expected, the modulus plateau values increased with gelatin concentration increasing and G` was higher in the solutions with modified corn starch. G` and G`` values attained the highest observed values at lower temperatures. Hydrolyzed collagen did not show gel formation ability. When 25 % of the gelatin content was substituted by AMCS, the observed values of G` were similar to those corresponding to pure gelatin suspensions. A phase separation study was carried out with gelatin and AMCS aqueous suspensions using confocal laser scanning microscopy. The results showed that the two biopolymers co-exist, without phase separation in a system containing 37,5 % of gelatin and 62,5 % of AMCS (based in a 10 wt% total solids). In general, the others systems showed phase separation, which was more intense with increasing gelatin/AMCS concentration. The rheological behavior in compression and the optical proprieties of diet gelatin gummy enriched with hydrolyzed collagen were also studied. The gummies were prepared with maltitol syrup and xilitol. The analysis of texture and opacity parameters showed that significant effects (p<0.05) were not observed in the interaction between the two factors with regard to samples hardness. High concentrations of gelatin and hydrolyzed collagen resulted in a high opacity. The rheological behavior in compression and the optical proprieties of gelatin/AMMA gels were also studied. When AMCS was introduced into gelatin gels, the system structure... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Gelatin, Collagen, Reologia, Gelatina, Colágeno, Gelitificação, Amido de milho modificado, Gomas comestíveis - Estrutura
Como citar
MARFIL, Paulo Henrique Mariano. Estudo reológico de sistemas gelatina/colágeno/amido para obtenção de géis e aplicação dietéticas de gelatina. 2010. 126 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências, Letras e Ciências Exatas, 2010.