Powder structure and gelation behaviour of debranched cassava starches prepared with and without incubation

The effect of incubation after debranching on the powder structure and gelation behaviour of debranched cassava starch (DBCS) was investigated. The DBCS samples were prepared by debranching 10% (w/v) cassava starch with pullulanase at 55 °C for 24 h, then incubated at 4 °C for 0, 1, 4, 24, and 72 h and recovered by precipitation with ethanol. The unincubated DBCS appeared as small, sponge-like aggregates with a rough surface while the incubated DBCS powders were considerably larger, looked denser, and had a smooth surface. The unincubated DBCS had an A + V-type crystal structure whereas incubated DBCS samples had a B-type structure. Crystallinity of all DBCSs was 20–22%. The incubated DBCSs displayed a substantially lower gel setting time compared to the unincubated DBCS, i.e., the gel setting time of 10% DBCSs cooked for 10 min reduced from 242 min for to 47–52 min when kept at 25 °C. The difference of gel setting time was most likely related to the type of crystal formed as well as the difference in amorphous structure, as indicated by the content of the slowly digestible starch fraction.