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Purpose: To investigate the effect of different oligosaccharides on the physicochemical properties of corn starch.
Methods: The blue value and retrogradation of corn starch were evaluated following the addition of different oligosaccharides and compared with control. Pasting properties, melting enthalpy and melting temperature were determined by rapid viscosity analysis (RVA) and differential scanning calorimetry (DSC).
Results: Maltose, lactose and fructo-oligosaccharides significantly affected iodine binding ability of corn starch. Retrogradation of corn starch was significantly inhibited by maltose, xylooligosaccharide and fructooligosaccharides. RVA analysis showed that the addition of oligosaccharides increased the peak viscosity of corn starch (from 3180 cP to 3687 cP) but decreased that of corn starch (from 896cP to 625 cP). DSC analysis showed that there was a large reduction in recrystallisation of corn starch by oligosaccharide. The samples containing xylooligosaccharide and fructooligosaccharides showed lower melting enthalpy (142.7 J/g and 143.5 J/g, respectively) than that of control (209.4 J/g), and their onset temperature (-10.9 °C and -8.89 °C, respectively) were also lower than that of control (-5.92 °C). In addition, the melting enthalpy and melting temperature of the samples containing oligosaccharides also showed lower values than those of control during storage.
Conclusion: The finding that oligosaccharides modify the physicochemical properties of corn starch would be of practical importance in broadening their application prospects of the starch in the food and pharmaceutical industries.
Keywords: Corn starch, Oligosaccharides, Pasting properties, Iodine binding, Retrogradation, Water activity, Enthalpy