Effect of oxidation, cross-linking and dual modification on physicochemical, crystallinity, morphological, pasting and thermal characteristics of elephant foot yam (Amorphophallus paeoniifolius) starch

Published Date
April 2016, Vol.55:56–64, doi:10.1016/j.foodhyd.2015.11.003

Title 
Effect of oxidation, cross-linking and dual modification on physicochemical, crystallinity, morphological, pasting and thermal characteristics of elephant foot yam (Amorphophallus paeoniifolius) starch

• Author 

• Sakshi Sukhija
• Sukhcharn Singh
• Charanjit S. Riar ^,

• Department of Food Engineering & Technology, Sant Longowal Institute of Engineering & Technology (Deemed University), Longowal, 148106 Punjab, India

Received 14 August 2015. Revised 23 September 2015. Accepted 2 November 2015. Available online 7 November 2015.

Highlights

• •
  Cross-linking (20.5%), carbonyl (0.014–0.07%) and carboxyl content (0.04–0.14%).
• •
  FTIR and XRD analysis indicated modification of starch.
• •
  Modification improves water binding capacity and color value (whiteness) of starches.
• •
  Paste clarity (%T) decreased for cross-linked starch.
• •
  OCYS starch interrupted pasting properties and restricted gel formation.

Abstract

Elephant foot yam starch was chemically modified using sodium hypochlorite (NaOCl) and sodium trimetaphosphate (STMP), for the preparation of oxidized (OYS), cross-linked (CYS) and dual modified i.e. oxidized cross-linked (OCYS) and cross-linked oxidized (COYS) starches. Characteristics analyzed such as pasting, morphological, thermal, FTIR and XRD analysis indicated modification of starch which was further authenticated by determining the degree of cross-linking (20.5%), carbonyl (0.014–0.07%) and carboxyl content (0.04–0.14%). Modification significantly (P ≤ 0.05) improved water binding capacity and color value (whiteness) of starches. Temperature showed a positive effect on swelling power and solubility of native and modified starches, however in cross-linked starch the swelling power decreased. Paste clarity (%T) highly improved with oxidation and dual modification and decreased for cross-linked starch. A significant reduction in amylose content was observed following modification except for cross-linked starch. Increase in degree of crystallinity of oxidized and dual modified starches was depicted from X-ray diffractogram. Decrease in viscosity profile of modified starches was observed using Rapid Visco Analyzer (RVA) with no gel paste formation occurred for oxidized cross-linked starch. Studies on the phase transitions associated with gelatinization using DSC showed higher enthalpy values (ΔH_gel) for cross-linked and dual modified starches as compared to native and oxidized starch. The morphology of the starch granules presented surface fissures in case of oxidized and oxidized cross-linked starch, whereas smooth surface of native, cross-linked and cross-linked oxidized starches was observed.

Graphical abstract

Keywords

• Tuber starch
• Chemical modification
• FTIR
• XRD
• Morphology
• Thermal properties

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• ∗ 
  Corresponding author.

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