Efeito do Processamento e das Condições Ambientais nas Propriedades de Matérias Biodegradáveis de Amido de Aveia

Abstract

Resumo: A característica hidrofílica dos biomateriais a base de amido resulta em alta instabilidade diante de diferentes condições ambientais. O amido de aveia, por possuir um conteúdo maior de lipídios em relação a outros amidos, tornase uma fonte interessante, uma vez que a hidrofobicidade aumentada pode atuar reduzindo sua capacidade de sorção de umidade. O objetivo do trabalho foi investigar o comportamento de filmes e laminados de amido de aveia, produzidos por casting e extrusão, respectivamente, plastificados com glicerol, sorbitol e ureia e armazenados em diferentes condições de umidade relativa. Mesmo com a presença do lipídio nativo, os materiais ainda mostraram instabilidade diante do aumento da umidade relativa de armazenagem, sendo observado um decréscimo na força e um aumento na deformação nos testes de perfuração. Em geral os biomateriais plastificados com glicerol apresentaram maior capacidade de sorção de água. O sorbitol foi o plastificante mais efetivo, pois produziu materiais com propriedades mecânicas similares aos outros plastificantes mesmo sendo usado em menor concentração molar. O processo de extrusão resultou em materiais finais com estruturas mais abertas e fragmentadas. Palavras-chave: Aveia, amido, plastificante. Effect of Processing and Enviromental Conditions in the Properties of Oat Starch Biodegradable MaterialsAbstract: The hydrophilic character of starch-based biomaterials generates high instability under different environmental conditions. Oat starch shows an interesting alternative for starch films because it contains higher lipid content than other common starches. This increased hydrophobicity can act reducing the moisture sorption capacity. The objective of this study was to investigate the behavior of oat starch films and sheets produced by casting and extrusion, respectively, plasticized with glycerol, sorbitol and urea and stored at different relative humidity. Even with the presence of native lipid, the materials still showed instability upon increasing the relative humidity for storage. Under higher humidity, a decrease in strength and an increase in deformation in puncture tests were observed. Biomaterials plasticized with glycerol showed higher water sorption capacity. Sorbitol was the most effective plasticizer because it led to materials with similar mechanical properties to other plasticizers even at lower molar concentrations. The extrusion process resulted in final materials with more open, fragmented structures.

Development and characterization of biodegradable films from fermented yam (Dioscorea trifida L. f.)

“…That smaller amounts of water were adsorbed under treatment 3, corroborates the data of Mali et al (2005). According to Galdeano et al (2014), the glycerol is incorporated into the polymer matrix as it slowly adsorbs the water.…”

Physical, antimicrobial and antioxidant properties of starch‐based film containing ethanolic propolis extract

“…() and Galdeano et al . (). The differences may be related to the film's production methods, the amount of plasticiser added and the presence of EPE compounds that decreased its hydrophilicity.…”

“…With respect to the puncture test, the incorporation of 1% of EPE reduced significantly the puncture strength (P) from 22.2 N to 11.3 N. This can also be attributed to the plasticising effect of EPE increasing the flexibility of the films. The control films showed similar values of puncture strength with oat films plasticised with glycerol (17.32N) (Galdeano et al ., ) and cassava starch films with high amylose content (19.6 N) (Alves et al ., ). On the other hand, the films produced in this study were more resistant than banana flour films (6.0 N) and banana starch films (8.1 N) produced by Pelissari et al .…”

“…() for cassava starch films plasticised with glycerol or sorbitol and by Galdeano et al . () for oat starch films and sheets.…”

“…() and Galdeano et al . () with some modifications. Film specimens (5 mm × 5 mm) were previously conditioned in a desiccator containing silica gel (0% RH) for 2 weeks.…”