Minimizing polyphenols and enzymes degradation using hydrogel packaging with combined evaporative and daytime radiative cooling functions during ambient transportation.

Polyphenols and enzymes usually suffer from degradation during transportation due to the lack of a cold chain system in developing countries and regions. In this study, anthocyanin and trypsin were selected as examples of polyphenols and enzymes and investigated for minimizing their degradation during ambient transportation using hydrogel packaging with combined evaporative and daytime radiative cooling functions. A polyacrylamide/polyvinyl alcohol contained with nanoparticles (NPs@PAAm/PVA) hydrogel packaging was thus developed. The NPs@PAAm/PVA packaging exhibited desirable swelling behaviour, high solar reflectance, and strong atmospheric emissivity to synergistically achieve evaporative and daytime radiative cooling. The indoor experiments indicated that the vial with NPs@PAAm/PVA packaging realised sub-ambient temperatures under different working temperatures and humidities, and the field tests indicated that the vial with NPs@PAAm/PVA packaging could effectively preserve the anthocyanin and trypsin without degradation caused by strong sunlight and high temperature. Consequently, the NPs@PAAm/PVA packaging with evaporative and daytime radiative cooling effects has promising prospects for anthocyanin and trypsin transportation in an energy-saving and sustainable manner.