Enzymatic coupled mechanical defibrillation process for the production of corn (Zea mays) cob nanofibrillated cellulose: preparation, characterization and evaluation as Pickering emulsifier for oil-in-water emulsion

Nanofibrillated cellulose (NFC) is a type of nanocellulose with multiple functionalities. Typically, NFC is produced via mechanical high-pressure homogenization process. However, this process is energy intensive and the fibrous nature of NFC often causes instrument blockage. The present study aims to utilize endoglucanase enzyme as an environmentally-friendly approach to pretreat fiber structure prior to undergoing mechanical defibrillation for the production of NFC from corn cob. Alkaline- and bleached-pretreated corn cob was reacted with endoglucanase Fibercare R from 0 to 2.5% before passing through the high-pressure homogenizer. It was found that the incorporation of 0.02% endoglucanase was sufficient to soften the corn cob cellulose and further prevented the blockage of the homogenizer. Subsequently, the 0.02% endoglucanase-treated corn cob was passed through different homogenization cycles (0-10 cycles) for NFC production. The water retention, Zeta potential, and shear viscosity of the NFC increased with higher homogenization cycle during the NFC production and the resulting NFC had a gel-like consistency. Next, emulsifying-stabilizing properties of the NFC produced from cycle 0 to cycle 10 as well as their amount from 0 to 1% were also assessed. The increase in homogenization cycle and amount of NFC promoted emulsion stability can be observed from the low creaming index, which is mainly attributed to the high shear viscosity and G'G'' crossover of the emulsion. Overall, the NFC derived from corn cob via enzymatic coupled with high-pressure homogenization process has the potential to be used as gel-like stabilizer in oil-in-water food emulsion system. [GRAPHICS] .