Efeito da sonicação seguida de desramificação enzimática nas características estruturais e digestibilidade de amidos com alto teor de amilose
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Data
2016-11-11
Autores
Mathias, Jéssica Carolina [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Amido resistente tipo 3 (AR3) é o amido ou fração de amido que não sofre a ação das enzimas digestivas do trato gastrointestinal, sendo constituído principalmente por amilose retrogradada devido à sua forte tendência à reassociação. A sonicação é um tratamento físico capaz de quebrar as cadeias de amido em tamanhos moleculares menores por meio de cavitação. O objetivo deste trabalho foi avaliar o efeito do ultrassom seguido da desramificação do amido com isoamilase na formação de AR3 e suas características estruturais a partir de amidos de ervilha rugosa (AER) e de milho com alto teor de amilose (AMAA). Suspensões de amido (6,5% m/v) foram gelatinizadas por autoclavagem (121oC/30 min), submetidas ao tratamento com ultrassom a uma frequência de 30 KHz, potência de 30 W por diferentes tempos (0, 5, 10 e 15 min), desramificados com isoamilase (3U/g amido), autoclavados (121°C/30min), resfriados (4oC/24h), precipitados com etanol e liofilizados. Os amidos nativos e modificados foram caracterizados quanto ao teor de amilose, tamanho molecular dos componentes do amido (GPC), distribuição do comprimento das cadeias ramificadas da amilopectina (HPAEC-PAD), padrão cristalino e cristalinidade relativa (difração de raios-X), propriedades térmicas (DSC) e teor de AR3. Os AER e AMAA nativos tiveram 43,2 e 50,3 % de amilose, respectivamente, padrão cristalino tipo B e alta proporção de cadeias laterais longas da amilopectina (GP ≥37). A sonicação provocou, em ambos os amidos, a degradação das cadeias de maior comprimento (GP ≥37) e aumento na proporção de cadeias menores (GP 1 -5 e 6 - 12) da amilopectina, enquanto causou o rompimento das cadeias de materiais intermediários e cadeias mais longas de amilose à frações de menor massa molecular com maior capacidade de complexação com iodo. As entalpias de gelatinização e a cristalinidade relativa dos amidos modificados aumentaram com o aumento do tempo de sonicação, independente da fonte de amido. AER e AMAA gelatinizados tiveram, como esperado, baixo teor de amido resistente (1,92% e 2,57%, respectivamente). Após desramificação e retrogradação, o teor de AR3 aumentou para 50,56% e 53,38% nos AER e AMAA, respectivamente. A sonicação precedendo a desramificação causou um aumento no teor de AR3 em 21% e 48% para AER e AMAA, atingindo 61,15% e 79,17%, respectivamente, quando 15 min de sonicação foi usado. Esses resultados indicam que o uso de uma tecnologia limpa como o ultrassom precedendo a desramificação dos amidos é um modo eficiente para potencializar a produção de AR3.
Resistant starch type 3 (RS3) is starch or the fraction of starch that does not suffer the action of digestive enzymes from the gastrointestinal tract and is mainly composed of retrograded amylose due to its greater tendency to reassociation. Sonication is a physical treatment capable of breaking down starch chains into smaller molecular size fractions by cavitation. The aim of this study was to evaluate the effect of ultrasound followed by starch debranching with isoamylase on the formation AR3 and their structural characteristics from wrinkled pea starch (WPS) and high amylose maize starch (HAMS). Starch suspensions (6.5% w/v) were gelatinized by autoclaving (121°C/30 min), subjected to ultrasound treatment at a frequency of 30 kHz, power of 30 W for different times (0, 5, 10 and 15 min), debranched by isoamylase (3U/g for 48 h), autoclaved (121 °C/30 min), cooled (4°C/24h), ethanol precipitated and lyophilized. The native and modified starches have been characterized as the apparent amylose content, molecular size distribution of starch components (GPC), amylopectin branched-chain length distribution (HPAEC-PAD), X-ray pattern and relative crystallinity (X-ray diffraction), thermal properties (DSC) and RS content. The native WPS and HAMS had 43,2 and 50,3% of amylose, respectively, B-type crystalline pattern and a high proportion of long branch chains of amylopectin (GP ≥37). Sonication resulted in degradation of the longer chains (DP ≥37) and increase in the proportion of smaller chains (GP 1-5 and 6-12) of amylopectin for both the starches, while caused a break of the intermediate material and longer amylose chains in smaller molecular weight amylose fractions with higher capacity of iodine complexing. The retrogradation enthalpy and relative crystallinity of the modified starches increased with increasing sonication time, independent of the starch source. Gelatinized WPS and HAMS had, as expected low SR content (1.92% and 2.57%, respectively). After debranching and retrogradation, the AR3 content increased to 50,56% and 53,38% for the WPS and HAMS, respectively. Sonication preceding debranching caused an increase in AR3 content of 21% and 48% WPS and HAMS reaching 61.15% and 79.17%, respectively, when 15 min sonication time was used. These results indicate that the use of a clean technology as the ultrasound preceding debranching of the starch is an effective way to enhance the production AR3.
Resistant starch type 3 (RS3) is starch or the fraction of starch that does not suffer the action of digestive enzymes from the gastrointestinal tract and is mainly composed of retrograded amylose due to its greater tendency to reassociation. Sonication is a physical treatment capable of breaking down starch chains into smaller molecular size fractions by cavitation. The aim of this study was to evaluate the effect of ultrasound followed by starch debranching with isoamylase on the formation AR3 and their structural characteristics from wrinkled pea starch (WPS) and high amylose maize starch (HAMS). Starch suspensions (6.5% w/v) were gelatinized by autoclaving (121°C/30 min), subjected to ultrasound treatment at a frequency of 30 kHz, power of 30 W for different times (0, 5, 10 and 15 min), debranched by isoamylase (3U/g for 48 h), autoclaved (121 °C/30 min), cooled (4°C/24h), ethanol precipitated and lyophilized. The native and modified starches have been characterized as the apparent amylose content, molecular size distribution of starch components (GPC), amylopectin branched-chain length distribution (HPAEC-PAD), X-ray pattern and relative crystallinity (X-ray diffraction), thermal properties (DSC) and RS content. The native WPS and HAMS had 43,2 and 50,3% of amylose, respectively, B-type crystalline pattern and a high proportion of long branch chains of amylopectin (GP ≥37). Sonication resulted in degradation of the longer chains (DP ≥37) and increase in the proportion of smaller chains (GP 1-5 and 6-12) of amylopectin for both the starches, while caused a break of the intermediate material and longer amylose chains in smaller molecular weight amylose fractions with higher capacity of iodine complexing. The retrogradation enthalpy and relative crystallinity of the modified starches increased with increasing sonication time, independent of the starch source. Gelatinized WPS and HAMS had, as expected low SR content (1.92% and 2.57%, respectively). After debranching and retrogradation, the AR3 content increased to 50,56% and 53,38% for the WPS and HAMS, respectively. Sonication preceding debranching caused an increase in AR3 content of 21% and 48% WPS and HAMS reaching 61.15% and 79.17%, respectively, when 15 min sonication time was used. These results indicate that the use of a clean technology as the ultrasound preceding debranching of the starch is an effective way to enhance the production AR3.
Descrição
Palavras-chave
Amido resistente, Ultrassom, Retrogradação, Estrutura, Resistant starch, Ultrasound, Retrogradation, Structure