Preparation and characterization of okara cellulose crystals as the emulsifier in a pickering emulsion

Abstract

Okara, a major by-product in the processing of soybean-based products, is always reserved for low-value purposes. However, okara consists of cellulose that can be practically employed in the preparation of cellulose crystals. In this work, cellulose crystals were prepared from okara under different conditions (acid contents and reaction times) to maximize their emulsifying ability. The functional property of the cellulose crystals tended to improve with increasing acid content and reaction time of the hydrolysis. Cellulose crystals with potent emulsifying capacity were prepared at an okara: acid ratio of 1:10 and a hydrolysis time of 45 min. The emulsifying activity of the okara cellulose crystals (O–CC) was then explored in solutions with varying pH and salt concentrations. The surface charge on O–CC crucially affected the dispersibility of the O–CC stabilized emulsion, as evidenced by the inferior emulsion stability when the surface charges on O–CC were suppressed. The O–CC stabilized emulsion was tolerant to NaCl addition, supposedly because the particle size and surface activity of O–CC were sufficient to provide a steric barrier against drop coalescence.