Effect of ultrasound on isolation and properties of oat starch

Abstract

The aim of the present study was to analyse the effect of ultrasound (US) on the isolation and properties of oat starch. Starch isolation was done by a water extraction method and with sonication for 30 (US30), 45 (US45) and 60 (US60) min. The highest starch yield was found in US45 as 49.04 g.100 g-1 of oat flour when the extraction time decreased from 6 h to 45 min. The functional properties of starches, such as bulk density, water solubility index, dispersibility and water absorption capacity, ranged from 0.65 to 0.80 g.mL-1, 3.22 to 5.75%, 78 to 87.5% and 84.23 to 95.87%, respectively. US45 had lower bulk density and higher dispersibility than other starches. US treatments decreased the gelatinisation temperature ranges and increased the gelatinisation enthalpy values. The enthalpy of the gelatinisation value of oat starch was found as 8.45 J.g-1 and increased with sonication up to 13.65 J.g-1. Retrogradation endotherms were observed after 6 days of storage, and enthalpies of retrogradation were lower than in the gelatinised starches. Fourier transform infrared spectroscopy (FTIR) spectra showed that US treatment did not affect the functional groups of oat starch. US application during oat starch isolation gave desired results, such as time reduction, higher yields and increased functional properties.

Keywords

• colour
• retrogradation
• starch dispersibility
• starch gelatinisation