Characterization of Starches for Retort Applications

Abstract

The importance of finding label friendly starches for food applications continues to grow. Retort soup applications require starches that can hold up to extended processing times at high temperature. Native starches breakdown under these conditions requiring the use of a modified starch. Heat moisture treated (HMT) potato starch, thermally inhibited (TI) corn starch, TI tapioca starch, and TI rice starch were compared to chemically modified waxy corn starch commonly used in retort soup applications. The chemical composition, thermal properties, crystalline pattern, and pasting properties of the starches were determined. It was found that TI corn starch has the characteristics that best match those of the chemically modified starch however, it was not a one to one replacement in functionality for chemically modified starch. To improve on its functionality, it was blended with native tapioca or native waxy rice starch at 85:15, 75:25, and 50:50 ratios. These blends were then used to retort a cream of chicken soup. The thermal profile was recorded during retort for all soup formulations. The soup samples underwent 5 slow freeze thaw cycles to mimic possible warehouse conditions and accelerate the shelf life study. The samples were then evaluated for textural appearance, starch granule integrity, and viscosity. Both native starches improved the granule integrity of TI corn starch in the soup samples throughout 5 freeze thaw cycles with the waxy rice starch blends having the best textural appearance. The TI corn starch blended with 15% waxy rice offers the optimal balance of viscosity, starch granule integrity, and textural appearance.