High adsorption of ethylene by alkali-treated halloysite nanotubes for food-packaging applications

Fresh food products such as fruits and vegetables are usually degrading fast after harvest, notably due to the production of ethylene, an aging hormone, by the products. Therefore, ethylene adsorbents in the form of powders are commonly used in packaging to maintain the postharvest quality of fresh products. The use of naturally-based adsorbents is preferred for safe food-packaging applications. Here we studied halloysite nanotubes as natural ethylene scavengers. We tested the effect of storage conditions on the kinetics of ethylene adsorption. Raw halloysite nanotubes were subjected to alkaline treatment to increase their pore size. We compared the efficacy of raw halloysite nanotubes versus alkaline halloysite nanotubes. Materials were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. Results show that alkali-treated halloysite nanotubes have the highest ethylene adsorption capacity at 11% relative humidity and 23 °C. The ethylene adsorption kinetics data were slightly fitted to a pseudo-first-order model, and the rate constant of the ethylene adsorption was 0.7107 min−1. After 24 h, 49 μL of ethylene gas present in headspace was removed with 1 g of alkali halloysite nanotubes.