Changes in the Yield, Microstructure, and Physicochemical Properties of Sweet Potato Starch in Response to Different Extraction Techniques
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Abstract:
The sweet potato cultivar Shangshu No.19 was used as a raw material to assess the effects of different extraction methods, including traditional grinding, static extraction at room temperature, traditional grinding-CaCl2 synergistic extraction, and shear emulsification, on the yield of sweet potato starch. Additionally, environmental scanning electron microscopy, transmission electron microscopy, and laser confocal microscopy were used to examine the microstructure of sweet potato residues following starch extraction. On the basis of the findings thus obtained, the optimal parameters for the different extraction methods were determined, and the structure and physicochemical properties of sweet potato starch obtained under the optimal conditions were elucidated. The results indicated that the optimal parameters for extraction using static extraction at room temperature, traditional grinding-CaCl2 synergistic extraction, and shear emulsification were as follows: standing for 3 days, 0.5% CaCl2 (mass fraction, m/m), extraction time of 16 h, shear emulsification time of 15 min, and shear emulsification rate of 22 000 r/min. Under these conditions, the yields of sweet potato starch for the three methods were 10.89%, 11.56%, and 18.81%, respectively, which were 2.71%, 3.38%, and 10.63% higher than the corresponding yields obtained using the traditional grinding method. Notably, virtually no starch particles were detected in the sweet potato residues obtained under the optimal shear emulsification conditions. Moreover, no significant differences were observed in the morphology or crystal structure of sweet potato starch obtained using the different treatments. In addition, the pasting characteristics and ΔH (14.07 J/g) of sweet potato starch obtained using the shear emulsification method were the lowest, thus indicating that this starch exhibits greater resistance to shearing and heat. These properties are conducive to regeneration, thereby facilitating the formation of starch gels with strong structural stability. These findings will provide theoretical guidance for the application of shear emulsification in the industrial extraction of sweet potato starch.
