# Oxidation Strength of PLA Filled with Algal Biomass and Rosemary Extract Powders for Food-Safe Handling

## TL;DR

This study evaluates how adding algal biomass and rosemary extract to PLA affects its resistance to heat-related degradation in food-contact applications.

## Contribution

The study introduces a comparative analysis of low-loading food-grade fillers to improve PLA's thermal and oxidative stability under repeated heating.

## Key findings

- Algal biomasses act as multifunctional fillers that influence PLA's thermal behavior.
- Rosemary extract and algal biomass show different stabilizing effects under repeated heating.
- The study provides insights into the recyclability and performance of algae-based PLA materials.

## Abstract

Poly(lactic acid) (PLA) is widely used in food-contact applications due to its bio-based origin, compostability, and transparency; however, its limited resistance to thermo-oxidative degradation remains a challenge for applications involving repeated thermal exposure. The moderate but repetitive heating conditions commonly encountered during food use and pre-recycling stages were analyzed for the samples filled with algal biomass and rosemary extract, additives accepted for use in the food industry. In this context, the present study introduces a comparative and application-driven approach by evaluating the effect of food-grade fillers—rosemary extract, spirulina biomass, and kelp biomass—incorporated at low loadings (0.5–3 wt%) on the thermal and oxidative behavior of PLA subjected to repeated heating at 80 °C. The presented results show algal biomasses as multifunctional fillers and benchmark their performance against a well-established natural extract. By combining DSC, FTIR, and chemiluminescence analyses, the study aims to clarify whether such bio-fillers act as stabilizing or destabilizing factors under realistic service-life thermal stress. This strategy provides insight into the suitability of algae-based fillers for food-contact PLA materials from both performance and recyclability perspectives.