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Native yam starch was modified by oxidation (with sodium hypochlorite), acid, and enzyme (with gluco‐amylase), respectively. Ash content, fat content, protein, and AM contents were reduced following modifications. All the modifications reduced swelling capacity whereas improved the solubility. The SEM of the native starch showed the presence of large oval or spherical to small irregular‐shaped granules, however, oxidation and hydrolysis caused collapse of the granules. From the XRD, the typical C‐type XRD pattern of the native starch changed to the typical A‐type XRD pattern of the three modified starches. The above results also demonstrated that amorphous region of yam starch granules was preferentially degraded than crystalline region of granules. DSC showed that oxidation and acid/enzyme hydrolysis reduced peak temperature of gelatinization (Tp) of native starch significantly. Enthalpy of gelatinization (ΔH) of oxidation and enzyme starch was reduced but it has no obviously change following acid modification.

Fritillaria ussuriensisMaxim. starch acetates with different degrees of substitution (DSs) were prepared by reacting native starch with glacial acetic acid/acetic anhydride using sulfuric acid as catalyst. XRD of acetylated starch revealed that there was loss of crystallinity with increasing DS. The carbonyl group signal at 1750 cm−1appeared in the FTIR spectra. The intensity of this peak increased whereas the intensity of the hydroxyl groups at 3000–3600 cm−1decreased. The thermal behavior of the samples was investigated and the results showed that the acetylation decreased the gelatinization temperatures and ΔHgel, and thermal stability of high DS acetylated starch (DS = 2.82) was much better than that of the original starch and partially substitute starch acetate (DS = 1.52). The SEM suggested that most of the starch granules were disintegrated into many visible fragments along with the increasing of DS. The starch acetate with different DS prepared in this paper has many potential uses in food and pharmaceutical applications for its lower gelatinization temperature and thermal stability properties.