Pirodextrinização do amido de inhame brasileiro (Dioscorea sp.) e caracterização físico-química das dextrinas resistentes

• Ano de defesa: 2018
• Autor(a) principal: Fuchs, Mighay Carlet Lovera
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Dioscorea sp; Pirodextrina; Metodologia de superfície resposta; Fibra dietética; Propriedades físico-químicas
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/35763

Pyrodextrins are starches modified under low moisture content by the action of heat or by a combination of heat and an acid catalyst. As resistant starch, pyrodextrins have different industrial applications, and are capable of generated similar physiological effects to dietary fibers and/or prebiotic carbohydrates. Therefore, this work was conducted to stablish the pyrodextrinization process of Brazilian yam starch (Dioscorea sp.) to produces enzymatically resistant yellow dextrins and to study the physicochemical and structural changes after pyroconversion. Native starch was extracted from yam tubers bought in the local market in Fortaleza (Ceará state) and a response surface central composite design was used to stablish the pyroconversion process with two factors: acid concentration (0.65−2.99 g of HCl/kg starch, dry basis) and incubation time (53−307 min). The highest levels of both factors negatively affected the available starch (AS) content, although positively influenced the color difference (ΔE). The best condition to produce a resistant dextrin was found treating the native starch with 1.82 g HCl/kg for 307 min at 140 °C, which produced a yellow dextrin containing 46.6 % of AS with 24.5 of ΔE, 6.6 % of dextrose equivalent, high solubility and very low viscosity. Resistant pyrodextrins were mixtures of starch derivatives with an average molecular mass between 36−71 kDa, determined by size exclusion chromatography. The analyses of infrared spectrums of dextrins, showed a less occurrence of α(1,4) glucosidic linkages and degree of short-range ordering of pyroconverted starches. These changes in molecular structure explain some of the reduction in digestibility (30−54 % of AD compared to native starch, p < 0.05), measured by the consecutive hydrolysis with α-amylase and amyloglucosidase. Finally, yam resistant pyrodextrins were materials with low in vitro digestibility and had similar functional properties compared to commercial dextrins from potato starch, therefore, they are promising materials for soluble dietary fiber.