An electrochemical approach for citric acid treatment of corn starch granules
2016
Hernandez‐Jaimes, Carmen | Vernon‐Carter, Eduardo Jaime | Lobato‐Calleros, Consuelo | Bello‐Perez, Luis Arturo | Alvarez‐Ramirez, Jose
An electrochemical method for citric acid treatment of corn starch granules at room temperature was explored. The idea was to take advantage of the electrochemical decomposition of citric acid and the enhanced mobility of the resulting chemical species into the starch granules. Corn starch dispersions (20% w/v; 1.0 M citric acid solution; 20°C) were subjected to ±1.0 V, triangular‐shape potential cycles at 1.0 Hz in an electrochemical cell endowed with a platinum electrode and a saturated mercury sulphate reference electrode under gentle stirring. SEM images and particle size distribution showed that the starch granules shrank, possibly due to leaching of starch chains and superficial hydrolysis reactions. X‐ray diffraction analyses indicated decrease of crystallinity content without alteration of the crystallinity type. Differential scanning calorimetry indicated a significant reduction of the gelatinization enthalpy. The citric acid‐treated starch granules showed increased hydrophobicity and reduced susceptibility to acid hydrolysis (2.0 mol/L HCl).
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