APPLICATION OF DIFFERENTIAL SCANNING CALORIMETRY TO AMARANTH STARCH GELATINIZATION - INFLUENCE OF WATER, SOLUTES AND ANNEALING

Gelatinization phenomena of amaranth starch were investigated using differential scanning calorimetry. Slight variations in onset (To) and peak (Tp1) temperatures were observed at moisture contents over 0.48 g water/g total. However, completion temperature (Tc) increased significantly. The intermediate transition temperature (Tp2) appeared at 0.61 g water/g total and below. The degree of gelatinization decreased by decreasing the moisture content. The three transition temperatures (To, Tp1 and Tc) were increased and gelatinization delayed as the concentration of sucrose was enhanced. The three latter transition temperatures tended to increase as the sodium chloride was raised to 0.066 g/g total, but further increases in salt reduced significantly these temperatures. The gelatinization was delayed by increasing the salt concentration. After annealing for 12 h at 25 to 65-degrees-C, starch samples exhibited higher To and Tp1 values, and narrowed gelatinization ranges. The degree of gelatinization augmented up to the annealing temperature of 55-degrees-C and significantly decreased thereafter.