Quercetin-Grafted-Starch/Polylactic Acid (Pla) Composite Film for Active Food Packaging Applications

Date of Award

7-1-2022

Document Type

Thesis

Degree Name

Master of Science in Chemistry

First Advisor

Jose Mario A. Diaz, PhD

Abstract

Due to environmental concerns, researchers made efforts to study biopolymers that can potentially replace petroleum-based plastics in the market. Starch is one of these biopolymers. Starch alone, however, is inadequate to form materials with desirable properties so it is usually blended with other polymers like polylactic acid (PLA). Aside from enhancing the biodegradability, plastic packaging is also being developed to help improve the shelf-life of food. This type of packaging material is known as “active packaging”. In this study, quercetin was grafted to starch using Ascorbic acid/ Hydrogen peroxide as initiators. The antioxidant films were then fabricated by blending quercetin-g-starch (QgS) and PLA.

Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy were done to verify the presence of quercetin in the conjugate. The amount of quercetin grafted to starch is 42.91 mg QE/g dry polymer, which is higher compared to some grafted biopolymers made with the same initiator systems. The Thermogravimetric analysis (TGA) of QgS proved that the thermal properties of the grafted starch were unaffected by the grafting method. The crystallinity of the starch moiety in QgS was also unaffected but an additional peak at 27.4° ascribable to quercetin appeared in the X-ray Diffraction (XRD) spectrum of QgS. QgS/PLA films exhibited lower tensile strength than pure PLA due to aggregation of particles within the films. Still, they exhibited higher antioxidant activity with the following concentrations: 29.59%, 76.14%, 79.43% and 77.05% for 0.5%QgS, 1%QgS, 3%QgS and 5%QgS films, respectively. Thus, a bio-based active packaging material with good antioxidant properties was successfully fabricated. This material can further be developed to cater to the needs of the food packaging industry.

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