A A C C   2 0 0 0   A n n u a l   M e e t i n g

The effects of amylose content on thermal properties of starches, dough rheology and bread staling were investigated using starch blends of two waxy wheat lines and one non-waxy wheat. Amylose content of starch blends ranged from 0% to 24%. Gelatinization enthalpy of starch blends increased as the proportion of waxy starch increased: from 10.5 J/g (0%) to 12.5 J/g (25%); and to 13.1 J/g (50%). Regrogradation enthalpy of starch blends after 96hr storage at 4°C decreased: from 2.2 J/g (0%) to 1.81 J/g (25%); and to 1.39 J/g (50%). As the proportion of waxy wheat starch increased from 0 to 50%, there were decreases in peak viscosity temperature of starch blends from 95 to 70°C and increases in peak viscosity from 225 to over 800 B.U. Mixograph absorption of a mixture of gluten and starch blends increased as the proportion of waxy wheat starch increased, while there were no changes in mixing time. Lower rheofermentometer dough height, higher CO(2) production and lower gas retention coefficient were observed in starch blends with 25 or 50% waxy starch. While volume of bread baked from a mixture of gluten and starch blends increased from 730ml with 0% waxy starch to 800ml with 25% and to 815 ml with 50%, bread exhibited more porous crumb structure as the proportion of waxy starch increased. Crumb moisture content and Aw were higher in breads with waxy wheat starch after 7 days storage at 4°C than bread without waxy wheatstarch. However, bread with waxy wheat starch exhibited higher retrogradation enthalphy of bread crumb (4.56J/g at 25% and 5.43 at 50%) than bread without waxy wheat starch (3.82 J/g).