Effect of dual modification with annealing, heat moisture treatment and cross-linking on the physico-chemical, rheological and in vitro digestibility of underutilised kithul (Caryota urens) starch
2020
Sudheesh, Cherakkathodi | Sunooj, Kappat Valiyapeediyekkal | Alom, Mahbubul | Kumar, Sunny | Sajeevkumar, Vallayil Appukuttan | George, Johnsy
Kithul starch was subjected to annealing, heat moisture treatment, cross-linking, annealing after cross-linking and heat moisture treatment after cross-linking and its physico-chemical, functional properties and in vitro digestibility was studied. Moisture and amylose content significantly (p ≤ 0.05) reduced after modifications. Phosphorus content of kithul starch increased after cross-linking. X-ray diffraction pattern (type A) did not change and crystalline properties increased after modifications. HLS (cross-linked heat moisture treated kithul starch) showed highest relative crystallinity among the modified starches. Swelling index, solubility and light transmittance decreased after modifications. Single and dual modifications caused severe damages such as fissures and holes on the granular surface. Peak viscosity of ANS (annealed kithul starch), CLS (cross-linked kithul starch) and ALS (cross-linked annealed kithul starch) increased and HMS (heat moisture treated kithul starch) and HLS (cross-linked heat moisture treated kithul starch) decreased as compared with NS (native kithul starch). Modified kithul starches showed lower break down viscosity and higher set back and final viscosity. Rheological analysis showed higher hardness of modified starch gel (higher storage and loss modulus) as compared with NS gel. In vitro digestibility decreased after modifications and HLS showed higher resistant starch (RS). Gelatinization temperature varied after modifications. Enthalpy of gelatinization significantly increased after single and dual modifications.
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