Effect of Chemical Modifications on Cassava Starch Functional Properties

摘要

The retrogradation, glass transition, and physical ageing behavior of modified cassava starches, including acetylated, cross-linked, and combined acetylated and cross-linked starches were studied by differential scanning calorimetry (DSC). The texture of fresh starch gels and the increase in gel hardness during storage was also monitored, as well as gelatinization behavior. The modified starches were prepared from granular starch and had a degree of substitution in the range 0-0.053. The glass transition temperatures (Tg) of the modified starches were 3-6 °C significantly lower than the non-modified starch. The physical aging peak temperatures were significantly reduced by 2-3 °C, compared to the non-modified starch, while aging enthalpies increased. Starch modifications, in particular acetylation, showed the ability to reduce amylopectin retrogradation rate, but no significant reduction in total retrogradation was observed. Fresh gels from acetylated starch and cross-linked starch were significantly less hard and harder respectively than the non-modified control.During storage, the non-modified control starch became significantly harder than the modified starches, which confirmed that acetylation or cross-linking can limit textural changes during storage, even at low degrees of modification. Different modifications controlled different properties of the starch system, with cross-linking influencing mainly the gelatinization behavior and acetylation controlling the changes in starch gel texture during storage.