The instrument was calibrated using a white standard colour calib

The instrument was calibrated using a white standard colour calibration plate. The colour difference (ΔE∗) as compared to a white standard tile was calculated using Eq. (4). equation(4) ΔE∗=(L∗-Ls∗)+(a∗-as∗)+(b∗-bs∗)where L∗, a∗ and b∗ are the colour

attributes of the starch film samples and Ls∗, as∗ and bs∗ are the colour parameters of the white standard tile. The opacity (Y) was calculated from the relationship between the opacity of the film superposed on the black standard (Yblack) and the relationship between the opacity of the film superposed on the white standard (Ywhite) according to the Eq. (5). equation(5) Y=YblackYwhite×100 S3I-201 The tensile strength and percentage of elongation at break was evaluated by a tensile test using a Texture Analyser (TA.XTplus, SB431542 datasheet Stable Micro Systems) based on the ASTM D-882-91 method (1996). The films were cut in strips (25 mm × 85 mm) and conditioned for 2 days. Before testing, the thickness of the strips was measured at eight points. The force and distance were recorded during extension of the strips at 0.8 mm/s up to break. The tensile strength

was calculated by dividing the maximum force by the film cross-section. The Young’s modulus was calculated by inclination of curve tensile strength by deformation. The tensile strength (Eq. (6)) and percentage elongation (Eq. (7)) values were calculated with the following equations: equation(6) TS=FmA

equation(7) E=drd0×100where TS is the tensile strength (MPa); Fm is the maximum force (N); A is the area of film cross-section (thickness × width; m2); E is the elongation (%); d0 is the distance onset of separation (cm); and dr is the distance of rupture (cm). Water vapour permeability (WVP) tests were conducted using the E96-95 ASTM standard method (ASTM, 1995). Each film sample was sealed over the circular opening of a permeation cell containing anhydrous calcium chloride (0% RH). These cells were then placed on desiccators with a saturated sodium chloride solution (75% RH) at 25 °C. After the samples reached steady-state conditions, the cell weight was measured at 24 and 48 h. The WVP was calculated by the Eq. (8). equation(8) WVA=ΔWtXAΔPwhere WVP is the water vapour permeability Resminostat (g mm/m2 dia kPa.); ΔW is the weight gain by desiccant (g); X is the film thickness (mm); t is the incubation time period (days); A is the area of the exposed film surface (m2); and ΔP is the difference of partial pressure (kPa). Analytical determinations for the samples were done in triplicate, and the standard deviations were reported. A comparison of the means was ascertained by Tukey’s test with a 5% level of significance using analysis of the variance (ANOVA). The carbonyl contents, carboxyl contents, solubility and swelling power of the oxidised and HMT potato starches are presented in Table 1.

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