Pasting properties of blends of potato, rice and maize starches

• Pasting of blends showed interactions between the starches in the blend.
• Peak viscosity of blends was lower than expected at low starch concentrations.
• Minimum and end viscosities were higher than expected at high starch concentrations.
• Reduced swelling in the blends led to more rigid granules.
• More interactions between leached material could lead to higher end viscosities.

In many food applications, chemically modified starches outperform their native starch counterparts. Starch blends are interesting clean label alternatives with potential for the food industry. Here, potato starch was blended with regular rice, waxy rice, regular maize or waxy maize starch in different ratios (100:0, 75:25, 50:50, 25:75 and 0:100). To elucidate the factors determining pasting, different total starch concentrations were used and swelling power and carbohydrate leaching were determined. During pasting, the starches in the blends impacted each other. Peak viscosities of the blends were lower than expected, especially at lower total starch concentrations (<6.0%) due to reduced swelling in the blend. At higher starch concentrations (>6.0%), the relation between peak viscosity and the percentage of a given starch in a blend was rather linear. Under such conditions, viscosity development is determined by granule rigidity rather than by swelling power. Minimum and end viscosities of the blends were intermediate between those of the individual starches at lower total starch concentrations. In contrast, at higher concentrations, minimum and end viscosities were as high as or even higher than the readings for potato starch, especially for blends of potato starch with rice or maize starch. Probably, reduced swelling led to a more conserved granular integrity during cooling which, along with interactions between leached molecules, can contribute to viscosity development. These results indicate that pasting of starch blends does not only depend on the individual starches and the blend composition, but also on the total starch concentration.

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