Development of modified cassava starches by ultrasound-assisted amylose/lauric acid complex formation

Abstract

Tuber starches have a smooth surface and a dense amylopectin structure, which prevents the formation of complexes with lipid compounds. The present study evaluated the effect of ultrasound on the formation of starch-lipid complexes on cassava starch’s structural, morphological, physicochemical, and digestibility properties. Lauric acid was added at concentrations of 0.075 and 0.15% w/v to previously swollen cassava starch suspension (60 °C, 1 h), and the mixtures were stirred and heated in an ultrasonic bath at 60 °C (power 100W, frequency 37 and 80 kHz for 1 h). The starch modification was confirmed by infrared spectroscopy, showing the presence of the C=O group. The modified starches presented a V-type crystalline structure and lower crystallinity due to the modification conditions, lauric acid concentration, and ultrasonic effect. Deformations and partial ruptures of starch granules were observed under microscopy. In addition, the modified starches showed decreased amylose content and solubility in cold water, higher stability during heating, and lower retrogradation, attributed to the presence of lipids. There was also an increase in resistant starch content due to the formation of complexes. In conclusion, ultrasound is a promising technique for driving the formation of cassava starch-lauric acid complexes, with modified properties which may be expand their potential use in the food industry.