The variability in thermal properties among 62 S 3 lines derived from a high-yielding exotic corn (Zea mays) population, Antigua 1 (PI 484990), was evaluated by differential scanning calorimetry (DSC). The S 3 lines were grown in Puerto Rico (1990Rico ( -1991 and Georgia (1994). Separate single-kernel starch extractions for five kernels (five replicates) from each line grown in each location were performed, and the starch was analyzed. The DSC values reported included gelatinization onset (T oG ), range (R G ), enthalpy (ΔH G ), and peak height index (PHI) and retrogradation onset (T oR ), range (R R ), enthalpy (ΔH R ), and percent retrogradation (%R) (an indication of the stability of gelatinized starch after storing at 4°C for 7 days). Significant differences (P< 0.05) were found among the 62 lines of Antigua 1 for T oG , R G , and PHI and highly significant differences (P < 0.01) were found for ΔH G . The starches from plants grown in Georgia (1994) had significantly (P < 0.05) greater T oG , ΔH G , and PHI but a significantly lower R G than those from Puerto Rico (1990Rico ( -1991. These data suggest that the starch from plants grown in Georgia (1994) might have a greater degree of crystallinity than that from Puerto Rico (1990Rico ( -1991 The variability in thermal properties among 62 S 3 lines derived from a high-yielding exotic corn (Zea mays) population, Antigua 1 (PI 484990), was evaluated by differential scanning calorimetry (DSC). The S 3 lines were grown in Puerto Rico (1990Rico ( -1991 and Georgia (1994). Separate single-kernel starch extractions for five kernels (five replicates) from each line grown in each location were performed, and the starch was analyzed. The DSC values reported included gelatinization onset (T oG ), range (R G ), enthalpy (∆H G ), and peak height index (PHI) and retrogradation onset (T oR ), range (R R ), enthalpy (∆H R ), and percent retrogradation (%R) (an indication of the stability of gelatinized starch after storing at

The changes in thermal properties of maize starches during five stages of kernel maturity, (12, 18, 24, 30, and 36 days after pollination [DAP]), from three mutant genotypes, amylose extender (ae), sugary-2 (su 2 ), and waxy (wx) in an OH43 background, and the OH43 genotype were studied using differential scanning calorimetry (DSC). Within a genotype, DSC values of starches at 24, 30, and 36 DAP were similar to each other and often were significantly different (P < 0.05) from the values at 12 DAP, indicating possible differences in the fine structure of starch during endosperm development. For su 2 starches, the gelatinization onset temperature (T oG ) significantly decreased after 12 DAP and remained low throughout the study. The gelatinization range (R G ) had a similar pattern. For wx starches, T oG at 18 DAP was significantly lower than at 12 DAP but tended to increase after 18 DAP. The R G increased significantly after 12 DAP and significantly decreased after 30 DAP. Thus, thermal properties of starches during early development were different from those of their mature counterparts, and differences among the mutant genotypes and the normal starch originated from the earliest endosperm development stage studied (12 DAP). RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. The changes in thermal properties of maize starches during five stages of kernel maturity, (12, 18, 24, 30, and 36 days after pollination [DAP]), from three mutant genotypes, amylose extender (ae), sugary-2 (su 2 ), and waxy (wx) in an OH43 background, and the OH43 genotype were studied using differential scanning calorimetry (DSC). Within a genotype, DSC values of starches at 24, 30, and 36 DAP were similar to each other and often were significantly different (P < 0.05) from the values at 12 DAP, indicating possible differences in the fine structure of starch during endosperm development. For su 2 starches, the gelatinization onset tem-