Structural changes in popped sorghum starch and their impact on the rheological behavior

• Published in: International journal of biological macromolecules 2021-09, Vol.186, p.686-694
• Main Authors: Cabrera-Ramírez, A.H., Morales-Sánchez, E., Méndez-Montealvo, G., Velazquez, G., Rodríguez-García, M.E., Villamiel, Mar, Gaytán-Martínez, M.
• Format: Article
• Language: English
• Subjects: Carbohydrate Conformation; Edible Grain - chemistry; Food Handling; Hot Temperature; Popped sorghum starch; Rheology; Sorghum - chemistry; Starch - chemistry; Starch - isolation & purification; Structural characteristics; Structure-Activity Relationship; Viscosity; Water - chemistry
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2021.07.018

Sorghum has been used to expand snacks such as pop sorghum. However, it is still unknown how the structural changes during the popping affect its rheological and functional properties. This study evaluated the structural changes of popped sorghum starch (PS) and their impact on rheological behavior. Moisture sorghum was adjusted to 11, 15, and 20% before popped. Morphology, X-ray pattern (XRP), infrared spectra (IR), thermal properties, and rheological behavior before and after popping were evaluated. Micrographs showed a honeycomb-like structure in PS. XRP showed partial damage to the orthorhombic crystals of the sorghum starch after PS, while the growth of crystalline lamellae was also generated (13.08 and 20.01°). IR showed structural damage as the signal at 1045 cm−1 disappeared in PS. The IM increased to gelatinization of the starch. The rheological behavior of PS displayed better thermal stability, with the lowest breakdown (25 ± 3.5 cP), setback (253 ± 11.3 cP), and final (1337 ± 5.7 cP) viscosity. The consistency coefficient k and flow behavior index n increase, meaning a loss of the pseudoplastic character. Viscoelastic properties increased in PS, suggesting the formation of cross-links and a stable matrix. Correlation analysis showed a strong relationship between structural changes and the rheological behavior of PS. [Display omitted] •The popping process changed the type-A starch pattern to V-type.•The new V-type patter was due to the lamellae growth of popped starch.•Viscosity of popped sorghum starch was stable regardless of the temperature profile.•K increased as the moisture rose due to the gelatinization degree of popped starch.•IM of 15–20% produced the best rheological behavior in popped sorghum starch.