Effects of oligosaccharides on pasting, thermal and rheological properties of sweet potato starch

- Addition of sugars increased pasting temperature of sweet potato starch (SPS).
- Addition of sugars decreased peak, trough, final viscosities, and setback value of SPS.
- Addition of sugars increased gelatinization temperature and enthalpy of SPS-sugar mixtures.
- Sugars addition increased yield stress and consistency coefficient of SPS-sugar mixture.
- Addition of sugars promoted liquid-like characteristics of SPS-sugar mixed pastes.

Effects of sucrose, raffinose and stachyose on pasting, thermal, and rheological properties of sweet potato starch (SPS) were investigated. The results indicated that pasting temperature of SPS increased with increasing sugar concentration in the order of stachyose > raffinose > sucrose. Addition of sugars significantly decreased the peak, trough, and final viscosities as well as setback value. The gelatinization temperatures of SPS-sugar mixtures markedly increased with increasing sugar concentration in the order of stachyose > raffinose = sucrose, gelatinization enthalpy also increased when sugar was added at high concentration compared with native starch. The addition of sugars increased the yield stress and consistency coefficient of SPS-sugar mixed pastes. The SPS-sugar mixed pastes exhibited a pseudoplastic and shear-thinning behavior under yield stress condition. Moreover, storage moduli (G′) of SPS-sugar mixed pastes decreased with addition of sugars. This study also showed that addition of sugars promoted liquid-like characteristics of SPS-sugar mixed pastes.