179: Food Packaging with Integrated Functions of Passive Daytime Radiation Cooling and Quality Maintenance

Introduction

Traditional electric cooling, a major energy consumer in the food supply chain, results in substantial energy waste and environmental challenges. There is an urgent need for non-electric, zero-emission methods for low-temperature food preservation. Passive daytime radiative cooling (PDRC) food packaging offers a promising solution by leveraging radiative cooling, where a surface emits more heat as infrared radiation than it absorbs, achieving cooling without external energy. This project develops innovative food packaging using partially oriented cellulose nanofibrils (CNFs) as solar reflectors and SiO2 as thermal emitters for PRDC, enhanced with TiO2 for preservation. The method assesses the material's cooling performance, barrier properties, and antimicrobial efficacy.

Methods

Films were developed using CNFs, SiO₂, and TiO₂ through mixing followed by semi-stretching or templating methods. Heat dissipation was evaluated via temperature differences between the ambient environment and the enclosed cavity beneath the material, supported by infrared thermal imaging. Microscopic morphology was analyzed using field emission SEM, while FTIR with ATR identified polymer infrared absorption peaks. Stress–strain behavior was tested using a tensile testing machine. Water vapor permeability (WVP) was assessed via a modified ASTM E96 method, and oxygen transmission rate with a MOCON OX-TRAN analyzer.

Results

The free-dried sample containing 1.2% SiO₂ achieved 24-hour continuous cooling with an average temperature reduction of 1.2°C as monitored by thermocouples during winter in Maine. Thermal imaging revealed that increasing SiO₂ content from 1% to 10% resulted in a 1.2°C drop, achieving a maximum total reduction of 2.8°C compared to control filter paper, effectively dissipating heat to delay spoilage. Samples prepared using a templating method with partially oriented CNFs demonstrated superior cooling, achieving a 2°C greater reduction than fully free-dried samples. These findings highlight the potential for designing advanced cooling food packaging materials.

Significance

This study focuses on developing passive daytime cooling materials from cellulose nanofibrils to address the urgent need for non-electric, zero-emission methods in low-temperature food preservation. The developed food packaging could reduce dependence on energy-intensive refrigeration, thereby decreasing greenhouse gas emissions and promoting sustainable solutions in the food industry. By leveraging naturally available polymers, this approach advances food packaging innovation and supports circular economy initiatives.

Authors: Zhijing Zhan, Jinwu Wang, Yiming Feng, Ling Li, Colleen Walker, Jun Yang, Mehdi Tajvidi, Qing Jin*