THERMAL-PROPERTIES OF STARCH FROM 62 EXOTIC MAIZE (ZEA-MAYS L.) LINESGROWN IN 2 LOCATIONS

The variability in thermal properties among 62 S-3 lines derived from a high-yielding exotic corn (Zea mays) population, Antigua 1 (PI 48499 0), was evaluated by differential scanning calorimetry (DSC). The S-3 lines were grown in Puerto Rico (1990-1991) and Georgia (1994). Separa te 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 (Delta H-G), and peak height index (PHI) a nd retrogradation onset (T-oR), range (R-R), enthalpy (Delta H-R), and percent retrogradation (%R) (an indication of the stability of gelati nized starch after storing at 4 degrees C for 7 days). Significant dif ferences (P < 0.05) were found among the 62 lines of Antigua 1 for T-o G, R-G, and PHI and highly significant differences (P < 0.01) were fou nd for Delta H-G. The starches from plants grown in Georgia (1994) had significantly (P < 0.05) greater T-oG, Delta H-G, and PHI but a signi ficantly lower R-G than those from Puerto Rico (1990-1991). These data suggest that the starch from plants grown in Georgia (1994) might hav e a greater degree of crystallinity than that from Puerto Rico (1990-1 991). None of the retrogradation values were significantly different a mong starches of the 62 lines of Antigua 1 and the starches from plant s grown in the two locations.