Particle-stabilizers modified from indica rice starches differing in amylose content

Octenyl succinic anhydride (OSA) starches were prepared from four cultivars of native indica rice starches with amylose contents of 1.90%, 18.01%, 25.40% and 26.98% (w/w). The emulsion stability and microstructure of the oil-in-water Pickering emulsions (soybean oil/water, 1/2, v/v) stabilized by OSA starch particles were investigated. Results indicated that the average droplet sizes of the emulsions were in the range of 10–70 μm, depending on starch cultivars. During 100 days of storage, the emulsions made from OSA starches (degree of substitution: 0.0287–0.0294) were stable. Optical microscopy showed that starch particles were accumulated at the oil–water interface in the form of a densely packed layer, which prevented the flocculation and coalescence of oil droplets by a steric mechanism. Moreover, the emulsification of particle-stabilizers was positively correlated with degree of substitution (P < 0.01) but had no obvious correlation with amylose content and pasting properties.