# Development and Characterization of Biodegradable Films on Native and Esterified Peruvian Purple Yam (Dioscorea trifida) Starches and Tara Gum

## TL;DR

This study explores how modifying Peruvian purple yam starch improves biodegradable film properties for sustainable packaging.

## Contribution

The study introduces a novel modification of purple yam starch with octenyl succinic anhydride to enhance film properties when blended with tara gum.

## Key findings

- Esterification reduced thermal properties by 3.4–7.6% compared to native starch.
- PYS-OSA:TG films showed higher tensile strength but lower elongation at break than PYS:TG films.
- Both film types disintegrated over 70% after 13 days in soil, indicating good biodegradability.

## Abstract

The aim was to evaluate if purple yam starch esterification with octenyl succinic anhydride (PYS-OSA) enhances the properties of purple yam starch (PYS)-based films in a blend with tara gum (TG). PYS was isolated from purple yam tubers (PYTs) with distilled water; then, starch was dual-modified by ultrasound (as a pretreatment) and esterification (PYS-OSA). The films PYS:TG and PYS-OSA:TG were characterized through physicochemical and mechanical characterization. The thermal properties (To, Tc, Tp, and ΔH) of PYS-OSA decreased in the range of 3.4–7.6% compared to PYS. Fourier transform infrared spectroscopy (FTIR) confirmed esterification, revealing two new absorption bands at 1563.0 and 1726.5 cm−1, and the degree of substitution (DS) was 0.023. The moisture content and solubility in water were 50.7 and 40.5% greater, respectively, for PYS-OSA:TG films compared to PYS:TG ones, but both films exhibited similar optical properties. The tensile strengths of PYS-OSA:TG films were higher than those of PYS:TG ones; however, the elongation at break was lower. PYS:TG and PYS-OSA:TG films were disintegrated by more than 70% after 13 days of being buried in soil. This work contributes to a better understanding of the starch isolated from purple yam tuber, with potential relevance for sustainable packaging applications.