Efeito de ácidos graxos saturados sobre as propriedades físico-químicas e digestibilidade do amido
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Data
2018-04-13
Autores
Marim, Marilia Gato
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Amidos e lipídios são constituintes importantes dos alimentos capazes de interagir e formar complexos de inclusão amilose-lipídios insolúveis e resistentes às enzimas digestivas. O objetivo deste trabalho foi avaliar o efeito dos ácidos graxos saturados (AGS), láurico (AL) e palmítico (AP), no comportamento de gelatinização dos amidos de mandioquinha-salsa (AMS), batata-doce (ABD) e ervilha rugosa (AER), os quais continham 6,7, 17,3 e 43,2% de amilose, além de avaliar a cristalinidade, estabilidade térmica e digestibilidade dos complexos formados a partir do cozimento de misturas amido-AGS. Mistura amido-8%AGS foi cozida em água (10% m/v), precipitada, lavada com etanol, seca e analisada quanto ao índice de complexação, cristalinidade, propriedades térmicas e digestibilidade. A adição de 8% AGS (baseado no peso seco de amido) reduziu o teor de amilose lixiviada, poder de inchamento e solubilidade, independente do amido. As viscosidades de pico e de quebra reduziram e houve alargamento dos picos nos AMS e ABD, enquanto o AER, independente da adição de AGS, teve baixa viscosidade nas condições tempo/temperatura usadas devido ao denso empacotamento da amilose. A temperatura inicial de gelatinização obtida por DSC aumentou nos três amidos, independente do AGS, mas apenas o AER mostrou picos de dissociação do complexo amiloselipídios (Tfinal > 104°C). A adição de AGS influenciou o comportamento de gelatinização dos amidos, que foi mais expressivo com o AL. A análise de componentes principais mostrou que o efeito da interação dos AGS na gelatinização foi semelhante para AMS e ABD, enquanto as amostras de AER foram bem discriminadas pelas propriedades térmicas. As misturas cozidas de amido-AGS tiveram alto índice de complexação (> 70 %) e padrão de raios-X tipo V com picos principais a 7o, 13° e 20° em 2, independentemente do amido e do AGS. As cristalinidades das misturas aumentaram significativamente quando comparadas àquelas dos amidos controle (sem AGS), principalmente para ABD-AGS que mostrou picos mais resolvidos. Os termogramas de todas as misturas cozidas mostraram picos endotérmicos referentes à dissociação dos complexos helicoidais, os quais foram classificados como amorfos tipo I, com temperaturas de pico próximas a 92 e 97oC, quando AL e AP, respectivamente, foram usados. Apenas a mistura AER-AP mostrou picos de dissociação de complexo cristalino (tipo II) com temperatura de transição entre 101,5 e 117,3 °C. A formação do complexo amilose-AGS foi afetada por diferenças estruturais de cada amido e pela disponibilidade da amilose que no AER não estava totalmente disponível para a formação de complexos. O AL, por ser mais solúvel, teve maior efeito que o AP na gelatinização dos amidos, porém após cozimento e lavagem das amostras com etanol, as misturas amido-AP foram termicamente mais estáveis devido à maior interação hidrofóbica com as cadeias de amilose. As misturas cozidas de amido-AGS tiveram sua digestibilidade consideravelmente reduzida com maior formação de amido resistente no AER (~51%), seguido do ABD (~36%) e AMS (~32%), independente do AGS utilizado.
Starches and lipids are important constituents of foods capable of interacting each other and forming amylose-lipids inclusion complexes that are insoluble and resistant to digestive enzymes. The aim of this work was to evaluate the effect of the saturated fatty acids (SFA), lauric (LA) and palmitic (PA), on the gelatinization behavior of peruvian carrot (PCS), sweet potato (SPS) and wrinkled pea (WPS) starches, which contained 6.7, 17.3 and 43.2% amylose, besides evaluating the crystallinity, thermal stability and digestibility of the complexes formed from the cooking of starch-SFA mixtures. The starch-8% SFA mixture was boiled in water (10% w/v), precipitated, washed with ethanol, dried and analyzed for complexation index, crystallinity, thermal properties and digestibility. The addition of 8% SFA (based on the dry weight of starch) reduced the content of leached amylose, swelling power and solubility, regardless of the starch. Peak and break viscosities reduced and there was an enlargement of the peaks in PCS and SPC, while the WPS, regardless of the SFA addition, had low viscosity at the time/temperature conditions caused by dense packaging of amylose molecules. The initial gelatinization temperature obtained by DSC increased in the three starches, regardless of the SFA, but only the WPS showed dissociation peaks of the amylose-lipid complex (Tend> 104 ° C). The addition of SFA influenced the gelatinization behavior of starches, which was more expressive with LA. Principal component analysis showed that the effect of AGS interaction on starch gelatinization was similar for PCS and SPS, while WPS samples were well discriminated by thermal properties. The cooked starch-SFA mixtures had high complexing index (>70%) and X-ray type V pattern with principal peaks at 7°, 13° and 20° in 2, regardless of the starch and SFA used. The crystallinities of the mixtures increased when compared to those of the control starches (without SFA), especially in the SPS-SFA that showed more resolved peaks. Thermograms of all the cooked mixtures showed endothermic peaks related with the dissociation of the helical complexes, which were classified as type I amorphous, with peak temperatures ranging from 92 to 97 °C, when LA and PA were used. Only WPS-PA mixture showed crystalline complex dissociation peaks (type II) with transition temperature between 101.5 and 117.3 °C. The formation of the amylose-SFA complex was affected by structural differences of each starch and by the availability of the amylose which in the WPS was not fully available for the formation of complexes. The LA, being more soluble, had higher effect than PA on the gelatinization of starches, but after cooking and washing the samples with ethanol, the starches-PA mixtures were thermally more stable due to the higher hydrophobic interaction between their amylose chains. Cooked starch-SFA mixtures had their digestibility considerably reduced with higher resistance to starch formation in WPS (~ 51%), followed by SPS (~ 36%) and PCS (~ 32%), regardless of the SFA used.
Starches and lipids are important constituents of foods capable of interacting each other and forming amylose-lipids inclusion complexes that are insoluble and resistant to digestive enzymes. The aim of this work was to evaluate the effect of the saturated fatty acids (SFA), lauric (LA) and palmitic (PA), on the gelatinization behavior of peruvian carrot (PCS), sweet potato (SPS) and wrinkled pea (WPS) starches, which contained 6.7, 17.3 and 43.2% amylose, besides evaluating the crystallinity, thermal stability and digestibility of the complexes formed from the cooking of starch-SFA mixtures. The starch-8% SFA mixture was boiled in water (10% w/v), precipitated, washed with ethanol, dried and analyzed for complexation index, crystallinity, thermal properties and digestibility. The addition of 8% SFA (based on the dry weight of starch) reduced the content of leached amylose, swelling power and solubility, regardless of the starch. Peak and break viscosities reduced and there was an enlargement of the peaks in PCS and SPC, while the WPS, regardless of the SFA addition, had low viscosity at the time/temperature conditions caused by dense packaging of amylose molecules. The initial gelatinization temperature obtained by DSC increased in the three starches, regardless of the SFA, but only the WPS showed dissociation peaks of the amylose-lipid complex (Tend> 104 ° C). The addition of SFA influenced the gelatinization behavior of starches, which was more expressive with LA. Principal component analysis showed that the effect of AGS interaction on starch gelatinization was similar for PCS and SPS, while WPS samples were well discriminated by thermal properties. The cooked starch-SFA mixtures had high complexing index (>70%) and X-ray type V pattern with principal peaks at 7°, 13° and 20° in 2, regardless of the starch and SFA used. The crystallinities of the mixtures increased when compared to those of the control starches (without SFA), especially in the SPS-SFA that showed more resolved peaks. Thermograms of all the cooked mixtures showed endothermic peaks related with the dissociation of the helical complexes, which were classified as type I amorphous, with peak temperatures ranging from 92 to 97 °C, when LA and PA were used. Only WPS-PA mixture showed crystalline complex dissociation peaks (type II) with transition temperature between 101.5 and 117.3 °C. The formation of the amylose-SFA complex was affected by structural differences of each starch and by the availability of the amylose which in the WPS was not fully available for the formation of complexes. The LA, being more soluble, had higher effect than PA on the gelatinization of starches, but after cooking and washing the samples with ethanol, the starches-PA mixtures were thermally more stable due to the higher hydrophobic interaction between their amylose chains. Cooked starch-SFA mixtures had their digestibility considerably reduced with higher resistance to starch formation in WPS (~ 51%), followed by SPS (~ 36%) and PCS (~ 32%), regardless of the SFA used.
Descrição
Palavras-chave
Complexo amido-lipídio, Amido resistente, Gelatinização, Starch-lipid complex, Resistant starch, Gelatinization