Soy protein isolate (SPI)-based composite films modified with nanocellulose (NC) and phenolic compounds extracted from date palm leave for packaging applications

The cultivation of date fruits and its related industry is huge in the United Arab Emirates (UAE) and in the Middle East. The date industry has a big status in this region and is considered as a part of the culture, but there is an increasing concern linked to the huge amount of waste produced from the date industry including seeds, leaves, press cake, and date wastewater. The improper management and utilization of these waste leads to environmental problems and increase processing costs.  Therefore, this study evaluated the valorization of date palm leaves through ‘green’ extraction of the phenolic compounds and nanocellulose for the development of soy protein isolate (SPI) based packaging materials. The structural, physiochemical, optical, mechanical, barrier, thermal, antioxidant, and antimicrobial properties of the composite films were explored. The incorporation of nanocellulose improved the SPI films’ physiochemical, mechanical, and barrier properties, while the addition of date leave extract (DLE) in liquid form (DLWE) endowed the antioxidant and antibacterial properties. It was worth noting that enriching the SPI-nanocellulose films with DLE in powder form (DLPE) improved the bioactive properties while maintaining the high mechanical and barrier properties. Therefore, this work provides a promising strategy for the formulation of functional biodegradable packaging films.