Effect of hydrocolloids and dry heat modification on physicochemical, thermal, pasting and morphological characteristics of cassava (Manihot esculenta) starch

In the present study, modification of cassava starch was carried out by carboxy methyl cellulose along with sodium alginate followed by dry heating at 130 °C for 2–4 h. The purpose of starch modification using natural ingredients was to study the characteristics which are indicators of broader application of starch otherwise achieved by chemical modifications of being considered non-natural. Physicochemical, pasting, thermal and morphological characteristics are chosen to explore the effect of modification on starch. Water and oil binding capacities as well as paste clarity increased whereas solubility and swelling power decreased significantly due to modification with hydrocolloids and dry heating. Pasting characteristics such as peak and final viscosities increased significantly with carboxy methyl cellulose and dry heating both, whereas with sodium alginate similar effect was admitted only after dry heating. The setback and breakdown of starch was also controlled significantly due to modification. Modification had a negative significant effect on thermal properties of starch such as To, Tp, Te and ΔH. Scanning electron micrographs revealed some surface cracking due to heat treatment which got diminished after prolonged heating and gum addition. Starch granules got agglomerated as a result of gum addition and initial heating because of leaching of amylose as well as due to decreased granule interspacing but the effect was reversed upon further heating. Granules cluster formation and agglomeration was more pronounced in carboxy methyl cellulose modification as compared to sodium alginate.