Autoclaving and ultrasonication for reducing digestible starch in cassava pulp: modification of cell wall composition, sorption properties, and resistant starch content

Autoclaving (15 min, 121 degrees C, 1 atm overpressure) and high-intensity ultrasound (3 pulses of 1 min, 750 W, 20 kHz, 80% amplitude) were evaluated individually or combined in cassava pulp to reduce the digestible starch and increase the fibre content. Ultrasound alone produced minimal modifications, and the subsequent autoclaving increased the oil-binding capacity and swelling. Autoclaving alone significantly increased total dietary fibre (TDF) from 14.7% to 21.4%, and the ratio of hemicellulose to lignocellulose. It also reduced the extractable starch from 42.7% to 7.5% and the resistant starch from 7.4% to 3.1%. Despite the higher digestibility, the starch digestion rate with pancreatic alpha-amylase was slower. Starch solubility increased at 25, 68, and 90 degrees C. Ultrasonication after autoclaving reduced the hemicellulose percentage, but the sorption properties remained unchanged. Resistant starch substantially increased to 39.9%, mainly composed of RS1 (inaccessible starch), and starch solubility decreased at the three temperatures assayed.

Automated summary

This study evaluated the effects of autoclaving and high-intensity ultrasound on cassava pulp to alter its starch and fiber content. Autoclaving significantly increased the fiber content and decreased digestible starch, while ultrasound had minimal effects. The combination of these methods further increased resistant starch but did not significantly alter the sorption properties.