Enzyme-resistant starch. I. Quantitative and qualitative influence of incubation time and temperature of autoclaved starch on resistant starch formation.
1993
Eerlingen R.C. | Crombez M. | Delcour J.A.
Wheat starch was autoclaved (121 degrees C) for 1 hr in excess water. The subsequent formation of enzyme-resistant starch (RS) was studied as a function of time (at different incubation temperatures, i.e., 0, 68, and 100 degrees C). The rate of formation and the maximum yields of RS (4, 6, and 10%, respectively) varied to a great extent. The relationship between incubation time, temperature, and the yields of RS was interpreted in terms of crystallization in an amorphous matrix, the starch gel being a partially crystalline polymer system. Upon incubation at 0 degrees C, the nucleation rate was high and the propagation rate was low; the opposite was the case upon incubation at 100 degrees C. At 68 degrees C, an intermediate pattern was observed. incubation of the autoclaved starch samples at two subsequent temperatures (0 and 68 degrees C or 0 and 100 degrees C) (two-step procedure) did not increase the RS yield significantly. X-ray diffraction showed qualitative differences among the crystallites formed at different temperatures. RS formed at 100 degrees C (A pattern) was different from that formed by incubation at 0 or 68 degrees C (B pattern). X-ray diffraction of RS formed in a process with two storage steps at different temperatures (0 and 68 degrees C or 0 and 100 degrees C), aiming at increasing yields by first favoring nucleation and then propagation, yielded B-type diffractograms.
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