Abstract
ABSTRACTPhysicochemical and digestion properties of chitosan modified starch prepared by dry heat treatment were investigated. Starch granule aggregation occurred following the addition of chitosan and this trend was enhanced with increasing chitosan concentration. The size of chitosan modified starch particles was about six times of that of the native starch granules. Interactions between the hydroxyl groups of starch and the amino groups of chitosan was confirmed by Fourier transform infrared spectroscopy analysis. The disappearance of the trough in the Rapid Visco Analyzer profile indicated that the cross-links increased the starch shear resistance. The cross-links between starch and chitosan also reduced starch digestion rate compared to the control (p < 0.001), and this reduction was further enhanced with an increasing chitosan concentration. Additionally, the addition of chitosan altered starch digestion kinetics from one phase to two phases, implying that chitosan modification changed both starch structure and its digestion behaviors.
Highlights
Starch is the most abundant storage glucan composed of two main structural components, amylose and amylopectin (Sajilata, Singhal, & Kulkarni, 2006)
More aggregated granules were formed and became inseparable when the concentration of chitosan was increased to 6%, which might be related to the increased interactions between chitosan and starch molecules (Figure 1(d))
This study found that the interactions between two polymers led to the band at 1638.19 cm−1 being split into two peaks, and more importantly, the absorption ratio of the two peaks was highly associated with the chitosan concentrations used in the system, which might further suggest that the interactions between the two polymers occurred during the treatment and were further enhanced following the addition of chitosan from 3% to 9%
Summary
Starch is the most abundant storage glucan composed of two main structural components, amylose and amylopectin (Sajilata, Singhal, & Kulkarni, 2006). Enzyme-driven starch hydrolysis is one of the fundamental metabolic processes in human digestion to maintain a proper blood glucose level. Based on the rate of digestion, starch can be classified as rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) (Englyst, Kingman, & Cummings, 1992). RDS and SDS, though differ in their digestion rates, are both digested completely in the small intestine, but cause a different increased glucose in the blood glucose levels (Chung, Shin, & Lim, 2008; Zhang & Hamaker, 2009). The effect of RS on human health has gained increasing interest in that it is not digested in the upper gastrointestinal tract, but is fermented in the large intestine with beneficial effects for the gut environment (Lafiandra, Riccardi, & Shewry, 2014). The applications of SDS and RS in foods can moderate glycemic response and maintain a healthy microorganism profile in the human gut
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