2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

The hypothesis of this study is that certain starch components (Intermediate Materials, IM) of corn may provide special properties with benefits for food applications. The objectives were to characterize the functional properties as well as to evaluate the fine structures of the IM in starch from corn mutants. Differential Scanning Calorimetry data revealed that the gelatinization onset temperatures T(oG) of starches from mutant lines ae25, du39, and su2, ranged from 52.4°C to 62.9°C, and were lower than that of the wild type starch (64.2°C). The value of the change in enthalpy of gelatinization of su2 was the lowest among all starches. Rapid Visco Analyser data showed that the peak viscosity, breakdown, and setback of the starches from the mutant lines were lower than that of the wild type starch. Texture Analyser TA-XT2 data indicated that the wild type and du39 gave the firmest gels after 1 and 7 days of storage respectively. The relative amount of IM in the corn starches was 9.9% in the wild type, 12.0% in ae25, 13.0% in du39, and 13.6% in su2. Another mutant corn line, su1, had 14.4% IM and the concentration of water-soluble phytoglycogen isolated by wet milling was 8.9 mg/ml of solution. Enzymatic debranching of phytoglycogen from the su1 mutant using high-performance anion-exchange chromatography determined the branch chain-length distributions to range from DP 4 to DP 41 with the peak branch chain-length at DP 12. Identifying the structures of the IM leading to desirable properties of the starches will aid to the development of value-added corn lines targeted for particular food applications.