Films of native and modified starch reinforced with fiber: Influence of some extrusion variables using response surface methodology

Corn starch (native and phosphorylated) and potato films containing glycerol as plasticizer, and bagasse sugar cane as fiber, were produced by extrusion‐calendering process, and characterized for the mechanical properties (tensile stress at rupture σr, elongation at break εb, and Young's modulus E), water disintegration index (WDI), water absorption capacity (WAC), and luminosity. The evaluated processing variables were: feed moisture, fiber content, and type of starch. The response surface methodology was applied to analyze, and the model of significance was justified by a variance analysis (F‐test). The inclusion of fiber provides a mechanical reinforcement to the starch matrix favoring the elongation at break (εb) in thickness films (280–350 μm). Samples formulated with potato starch within the values of feed moisture 18.25, 20.5, and 5 wt % of fiber content, showed an increment in values of tensile stress at rupture (3.80–4.4 MPa) and Young's modulus (78.47–68.04 MPa). Corn starch films with high fiber content (10%) and low feed moisture (18.25%) values showed a decrement in elongation at break (12.93%). WAC and WDI were low with minimum and intermediate levels of feed moisture and fiber content (0–5%). Luminosity values were an indicative that do not exist degradation in film materials due to condition extrusion process used. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012