Films based on oxidized starch and cellulose from barley

Abstract

Starch and cellulose fibers were isolated from grains and the husk from barley, respectively. Biodegradable films of native starch or oxidized starches and glycerol with different concentrations of cellulose fibers (0%, 10% and 20%) were prepared. The films were characterized by morphological, mechanical, barrier, and thermal properties. Cellulose fibers isolated from the barley husk were obtained with 75% purity and high crystallinity. The morphology of the films of the oxidized starches, regardless of the fiber addition, was more homogeneous as compared to the film of the native starch. The addition of cellulose fibers in the films increased the tensile strength and decreased elongation. The water vapor permeability of the film of oxidized starch with 20% of cellulose fibers was lower than the without fibers. However the films with cellulose fibers had the highest decomposition with the initial temperature and thermal stability. The oxidized starch and cellulose fibers from barley have a good potential for use in packaging. The addition of cellulose fibers in starch films can contribute to the development of films more resistant that can be applied in food systems to maintain its integrity.

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

“…X‐ray diffractograms of starches were obtained with an X‐ray diffractometer (XRD‐6000, Shimadzu). The relative crystallinity (RC) of the starch granules was calculated as described by Halal et al . by the equation: RC (%) = (Ac/(Ac + Aa)) × 100; where Ac is the crystalline area; Aa is the amorphous area on the X‐ray diffractograms.…”

“…Films were prepared by the casting technique, following the method described by Halal et al . The obtained film samples were stored at 16 °C and approximately 65% relative humidity (RH) using a saturated solution of ammonium nitrate (NH 4 NO 3 ) for 4 days.…”

“…Thickness was determined by using a micrometer to the nearest 0.001 mm, at eight random positions around the film . The tensile strength and the percentage of elongation at the break of the films were evaluated by a tensile test using a Texture Analyzer (TA.XTplus, Stable Micro Systems) based on the method ASTM D‐882‐91 from American Society for Testing and Materials (ASTM)…”

“…The solubility in water was calculated as the percentage of dry matter of the solubilized film after immersion for 24 h in water at 25 °C . The samples from each film were first dried at 110 °C to determine their initial dry weight.…”

“…This allows the gelatinized starch to form stable and flexible films . A growing number of research studies regarding the characteristics of starches from different botanical sources and their effects on the quality of biodegradable films have been published recently . Nonetheless, these studies reported the behavior of starch‐based films made from native and/or modified starches from a single source and cultivar.…”