Pasting, paste, and gel properties of starch–hydrocolloid combinations

A review with 267 references. Use of starch–hydrocolloid combinations is widespread, particularly in the food processing industry. Many studies have been conducted with a goal of understanding why the addition of a small amount of a hydrocolloid influences the properties of a starch-based paste, gel, or food product. Multiple variables are encountered in the research reports, including the use of different types of starches and hydrocolloids and different methods of preparation and evaluation of composite pastes and gels. Most commonly, a starch–hydrocolloid composite paste and/or gel exhibited (as compared to the starch alone paste and/or gel) increases in peak and final viscosities, short-term retrogradation, and gel strength and decreases in the temperature of the initial rapid viscosity increase, granule swelling, starch polymer molecule leaching from swollen granules, and long-term retrogradation; but opposite effects have also been observed. Most evidence seems to point towards the following mechanisms: hydrocolloid molecule interaction with leached starch polymer molecules—in some cases increasing network formation and in other cases decreasing or weakening the network formed by starch polymer molecules, changes in starch granule swelling (either positive or negative changes), swollen granule association via depletion flocculation, and phase separation between amylose, amylopectin, and hydrocolloid molecules in the continuous phase. The overall conclusion is that, because of the complexity of the variety of systems, several mechanisms are likely to be operating and the proportions of competing mechanisms likely vary with different specific hydrocolloids, different starches, and different methods of preparation of composite pastes and gels.