Eco-friendly and humidity-sensitive cellulosic triboelectric materials tailored by xylanase for monitoring the freshness of fruits

Detecting the freshness of fruits during the storage period plays crucial role in reducing food waste and food-borne contamination. In this study, for the first time, a novel humidity-sensitive tribopositive cellulosic material was successfully tailored by biological xylanase under mild conditions for monitoring the freshness of fruits within packing microenvironments. Benefiting from the more exposed -OH groups within created microstructures and the residual hydrophilic enzyme protein on the surface of fibers, the output voltage signal of the TENG decreased with gradual increasing the relative humidity (RH) from 25%RH to 95%RH. Moreover, the optimized TENG-72 h presents a higher humidity-sensitivity of V25% RH/V95% RH = 11.3 toward wide range humidity, which was about 3.65 times higher than pristine cellulose-based TENG. The constructed enzymatic cellulose TENG displayed discernible output signal response to the humidity within packaging microenvironments, which was highly correlated with the physiological parameters of fruits, further reveling the great potential application in monitoring the freshness of fruits. Overall, this research not only proposed a green and mild strategy for tailoring the humidity-sensitivity of cellulosic fibers, but also promotes the development of biodegradable triboelectric materials in the field of food safety.