Effect of Rice Starch Hydrolysis and Esterification Processes on the Physicochemical Properties of Biodegradable Films
Paola Chaves Martins, Vilásia Guimarães Martins
Abstract
Abstract Polymers such as starch are promising in the substitution of synthetic polymers in food packaging, but they present some inferior physicochemical properties. The chemical modification of starch can reduce the limitations of these polymers and make them suitable for packaging production. Therefore, the aim of this study is to elaborate, evaluate, and characterize biodegradable films produced from rice starch modified by hydrolysis and esterification processes. Rice starch hydrolyzed with 0.1 and 0.5 M hydrochloric acid (HCl) and rice starch esterified with 2% and 10% citric acid (CA) are used to produce the packages. The films are characterized in terms of their mechanical properties, optical characteristics, structural and thermal properties, water vapor permeability (WVP), water solubility (WS), and hydrophobicity. Films formulated from hydrolyzed starch show an increase in tensile strength (TS) (11.17 MPa) when compared to the control (1.83 MPa). In addition, the films obtained from hydrolyzed starch present lower solubility (15.6%) and higher relative crystallinity (RC) (71.6%) when compared to the control. The films produced by esterified starch show greater surface hydrophobility with a contact angle of 72.6° while the control shows an angle of 45.8°. Based on the above, the esterified and hydrolyzed starches are promising for the development of sustainable packaging.