Effect of moisture content on flow behaviour of molten soy‐protein isolate under an elevated temperature

Summary The flow behaviour of molten soy‐protein isolate (SPI) with moisture content ranging from 17 to 41% was measured with a capillary rheometer under an elevated temperature of 140°C. The flow‐starting temperature of SPI under 90 MPa pressure was inversely proportional to the moisture content. The relationship between flow rate and pressure drop for a molten SPI with 17‐35% moisture was non‐linear on a log‐log scale, while it was linear for a molten SPI with 41% moisture. Based on these results, the shear characteristic of a molten SPI with 41% moisture can be classified as a power‐law fluid with a flow behaviour index of 0.3. However, a molten SPI with 17‐35% moisture may be classified as an unknown type of non‐Bingham plastic.