Effect of the Incorporation of Rich-Amylopectin Starch Nano/Micro Particles on the Physicochemical Properties of Starch-Based Nanocomposites Developed by Flat-Die Extrusion

Abstract

Nanotechnology has been crucial in the development of environmentally friendly and naturally based materials for food packaging. In this work, an inexpensive and scalable way to develop amylopectin-enriched nanocomposites with nano/micro particles of starch is investigated. Cassava starch nanocomposites with rich-amylopectin starch nano/micro particles (SAP) are prepared by flat-die extrusion. SAP, obtained by applying shear stresses to an aqueous solution of native cassava starch using grinding, consists of (10.8 ± 0.9)% of nanofiller (< 200 nm) and (88 ± 1)% of micro-size particles (2-10 µm). After processing, great compatibility between SAP and the matrix is achieved. Nanocomposites with 15 wt.% of SAP show increases in Young's modulus (73%), tensile stress (30%), and tensile toughness (63%), and a decrease in water vapor permeability (34%) compared to the films without SAP (TPS). The use of 30 wt.% of SAP leads to a slight increase in crystallinity without significant changes in the overall properties, as a consequence of the combination of the effects produced by the presence of nanofiller and the enrichment of the matrix in amylopectin. This investigation provides a methodology for developing amylopectin-enriched starch nanocomposites with high compatibility between the nanofiller and the matrix as an attractive alternative for conventional starch-based packaging.