Effects of phosphorylating salts and temperature on the preparation of rice starch phosphates by extrusion
1999
Kim, C.-T.Shih, F.F.Champagne, E.T.Daigle, K.
Rice starch phosphates were prepared by the extrusion of rice starch with phosphate salts including sodium tripolyphosphate (STP), sodium trimetaphosphate (SMP), and a 50:50 mixture of STP and SMP (STP-SMP). The incorporation of phosphorus in the starch increased with increased barrel temperature ranging from 120 to 180ÝC. At 180ÝC, phosphorus contents for products treated with STP, SMP, and STP-SMP were 0.376, 0.194, and 0.360 %, respectively. The effects of phosphorylation on functional and rheological properties of the starch varied, depending on the extent of molecular degradation and the formation of intermolecular cross-linking caused by the heat and shear of extrusion. Generally, extrusion stabilized the pasting properties of the extrudates, whereas phosphorylation enhanced the pasting consistency of the starch products. Good correlation was observed between the extrusion specific mechanical energy (SME) and the product of solubility and intrinsic viscosity, indicating a close relationship between the energy input in the extrusion process and the performance behavior of the extruded phosphorylation products.
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