Mechanical properties of a high amylose content corn starch based film, gelatinized at low temperature

Abstract

SummaryIn the present study, a better knowledge of the influence of plasticizer content, storage relative humidity and film thickness on the mechanical properties of high amylose corn starch based films gelatinized at low temperature, is presented. The mechanical properties, tensile strength and percentage of elongation at break of high amylose corn starch films plasticized with glycerol were evaluated using tension tests. The films exhibited an increase in elongation and a decrease in tensile strength with increasing plasticizer concentration. When the glycerol level was high, some fissures were detected in the dry films, possible due to phase separation (starch-glycerol) phenomena. Film crystallinity is related to the reorganization capacity of the polymer chain, and thus the relative film crystallinity should increase with plasticizer content (glycerol and water). The mechanical properties were found to be strongly dependent on the water content due to the hydrophilic nature of starch films. The influence of moisture sorption on tensile strength was similar to that of plasticization with glycerol. The relationship between polymer chain mobility and water content explained this behavior. Elongation suffered a different effect and maximum values were reached at 45% relative humidity. The final drop in elongation was due to a softening of the structure at high relative humidity. The thicker the film the longer the drying time required, leading to greater relative crystallinity due to the corresponding increase in the possibility for chain reorganization. As a consequence, linear increases in tensile strength and elongation were observed with film thickness over the whole range studied (30 to 100 µm). Key words: Starch films; Mechanical properties; Tensile strength; Elongation at break; Crystallinity. Autores | Authors Maria Alejandra BERTUZZI Instituto de Investigaciones para la Industria Química (INIQUI -CONICET)Av. Bolivia 5150, A4408FVY Salta -Argentina e-mail: bertuzzi@unsa.edu.ar Juan Carlos GOTTIFREDI Margarita ARMADA Instituto de Investigaciones para la Industria Química (INIQUI-CONICET)Salta - Argentina, Mechanical properties of a high amylose content corn starch based film, gelatinized at low temperature Propriedades mecânicas de filme a base de amido de milho de alto teor de amilose gelatinizado em baixa temperatura Campinas, v. 15, n. 3, p. 219-227, jul./set. 2012 http://dx.doi.org/10.1590/S1981-67232012005000015 ResumoNo presente estudo, é apresentado um melhor conhecimento da influência do teor em plastificante, da umidade relativa de armazenamento e da espessura do filme nas propriedades mecânicas do filme baseado em amido de milho de alto conteúdo de amilose, gelatinizado em baixa temperatura. As propriedades mecânicas, a resistência à tração e a porcentagem de alongamento na ruptura dos filmes de amido de milho de alta amilose plastificados com glicerol foram avaliadas utilizando-se testes da tensão. Os filmes apresentaram aumento do alongamento na ruptura e diminuição da resistência à traç...

Mechanical and Physical Properties of Pea Starch Edible Films in the Presence of Glycerol

“…Hydrogen bonds between the starch chains are thought to contribute to the high TS value where these bonds bring about the high cohesiveness and low flexibility of the films (Bertuzzi et al . ).…”

“…Higher crystallinity leads to a polymer that is more rigid and less flexible (Kowalczyk et al 2014). Hydrogen bonds between the starch chains are thought to contribute to the high TS value where these bonds bring about the high cohesiveness and low flexibility of the films (Bertuzzi et al 2012).…”

Characteristics of starch from different bean genotypes and its effect on biodegradable films

“…Starch films with higher levels of amylose (BRS Pitanga and BRS Pérola) exhibited a higher tensile strength than the other films (Table ). Bertuzzi, Gottifredi, and Armada evaluated corn starch films with high amylose content and reported that tensile strength is favored by amylose crystallization.…”

Production of Gluten-Free Rolled Paper from Broken Rice by Using Different Hydrothermal Treatments

“…These results meaning the guarantees of adequate viscous, elastic and flexibility properties of these rice paper samples to possible deformation without breaking during filling [63]. On the other hand, the fracture toughness which measures the energy required to cause fracture [65] was significantly decreased in both parboiled treatments and increased in popped treatment.…”

“…These results indicated that the treated rice papers exhibited proper mechanical strength. That ensure its integrity and the resistance to fracture and cracks especially, during storage and reduces the defects, such as pinholes or fissures [61][62][63]. This is might be relates to the use of the gelatinized flour obtained by the hydrothermal treatments, which causes starch retrogradation [64] coupled with the interaction between rice flour and corn starch as a polysaccharide or polymer which useful to improve the mechanical properties [9].…”