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.