Acidity rectified aggregation behaviour of colloids in sugarcane juice

During processing and low-temperature storage, pH change affects the stability of sugarcane juice. This study investigated the colloidal stability and aggregation mechanisms of membrane-filtered sugarcane juice at the pH range of 2.5–9.5. The mechanisms of aggregate formation were speculated based on the compositional variations in sugarcane juice at different pH. When pH was lower than 6.03, aggregation was driven by the electrostatic effect, wherein proteins, polysaccharides and phenolic compounds interact, hence increase the average particle size and turbidity. The absolute value of the zeta potential of the juice was decreased and found an isoelectric point at the pH range of 3.0–3.5. However, under alkaline conditions, calcium phosphate mesh flocs, which are the dominant components of the aggregate, attract colloidal impurities in the juice, eventually resulting in a sharp increase in turbidity and the rapid formation of enormous precipitates, further increasing particle size. This work provides new clues to control aggregation issues commonly encountered by the sugarcane beverage industry.