Structural, physicochemical, textural, and thermal properties of phosphorylated chestnut starches with different degrees of substitution

Abstract

Phosphorylated chestnut starches (PCS) with different degrees of substitution (DS) in the range of 0.0000 to 0.1128 were prepared by changing the length of time of the esterification reaction. The structural, physicochemical, textural, and thermal properties of the resulting compounds were determined. Esterification affected the morphological structure of native chestnut starch (CS), resulting in cracks in the surface of PCS granules, as shown by scanning electron microscopy. Fourier transform-infrared spectroscopy revealed the intensities of characteristic peaks at 1019.51 and 859.44 cm−1 and that these increased with increasing DS, confirming the successful introduction of phosphate groups into CS molecules. Physicochemical analysis revealed that the transparency, solubility, expansibility, and freeze-thaw stability of PCS improved with increasing DS compared with native CS. Texture profile analysis showed that the hardness, brittleness, springiness, gumminess, and chewiness of the PCS decreased, whereas their adhesiveness and cohesiveness increased. Differential scanning calorimetry revealed a decrease in onset temperature, peak temperature, conclusion temperature, and the enthalpy value with increasing DS. Pasting properties indicated that the apparent viscosity and the viscosity stability of PCS were significantly improved and gelatinization temperatures reduced compared with native CS. Practical applications Food manufacturing and industrial processes are seeking new forms of modified starch with increased stability and improved quality for use in food products as a thickener, stabilizer, and functional ingredient. Phosphorylated starch is one of the most widely used modified starches. Compared with the original starch, phosphorylated starch shows good freeze-thaw stability, better swelling power, and strong anti-retrograde characteristics. However, little information is available for the physicochemical, morphological, textural, and thermal characteristics of Phosphorylated chestnut starches (PCS) with different DS. Thus, in the current study, PCS with different DS were prepared and their physicochemical, morphological, textural, thermal, and pasting characteristics were investigated. These results will help us to better understand the features of PCS, which could provide an alternative approach for chestnut reprocessing and the comprehensive utilization of its derivatives. We believe that the results of this study could also be useful for selecting suitable DS of PCS for different requirements in food manufacturing and other industrial processes.