Sunflower stem pith (SSP), an agricultural residue, was used to isolate the main source of the SSP cellulose. Cellulose nanofibril (CNF) with a length of about 2.0 μm and a width of approximately 26.3 nm was separated by using TEMPO oxidation from the SSP cellulose. Characterization of sunflower oil-in-water emulsions was assessed by visual inspection, emulsion index (EI), particle size, surface coverage, and rheology. The surface coverage ratio (SC) of emulsified droplets decreased from 8.8 to 0.5 with the variation of oil phase volume and SSP CNF phase content. Pickering emulsions (oil/water volume ratio was 1/9) prepared with CNF (0.5 wt%), which possessed the highest stability, and the smallest particle size. However, the high oil volume system resulted in polydispersity and larger droplet sizes. The storage modulus (G') and loss modulus (G") offered evidence for the rheological behavior of the emulsions. The findings indicated that it is feasible to stabilize oil-in-water emulsions using SSP cellulose. The integrated process is suggestive of viable methods for the industrial utilization of sunflower.
Keywords: Cellulose nanofibril; Pickering emulsion; Sunflower stem pith.
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