Soy hull nanocellulose enhances the stretchability, transparency and ionic conductance of sodium alginate hydrogels and application in beef preservation

Hydrogels with excellent mechanical performance, transparency and conductivity properties are attracting much attention as novel materials for use in food packaging, chemical substance detection and bioengineering scaffolds. However, integrating good stretchability, transparency and mechanical performance into a single conductive hydrogel is challenging. In this work, stretchable, transparent and conductive composite hydrogels were fabricated from soy hull nanocellulose (NCFs), sodium alginate (SA) and calcium chloride (CaCl2) using −80 °C cryogenic freezing, hydrogen and ester bond crosslinking and ion crosslinking methods. The prepared composite hydrogels have a three-dimensional network interior and exhibit excellent tensile (∼900 %), viscoelasticity (storage modulus 78.99 kPa), mechanical strength (compression strength 0.59 MPa, tensile strength 0.61 MPa), transmittance (∼90 %) and electrical conductivity (∼2.34 S/cm) properties. The excellent mechanical properties were retained after repeated stretching. Notably, preservation testing showed that the NCFs/SA/CaCl2-5 hydrogel could prolong the shelf life of beef by 5 d at 37 °C, Therefore, the NCFs/SA/CaCl2-5 hydrogels can be used in food packaging to extend the shelf life of meat products. Meanwhile, this work provides a new method for preparing tough, transparent and conductive nanocellulose hydrogels.