Effect of high pressure on thermal, structural and osmotic properties of waxy maize and Hylon VII starch blends

Hylon VII, waxy maize starch and their mixtures (1:1, 1:3, 3:1, w/w) were subjected to a high pressure treatment (650 MPa/9 min) in an excess of water (30%). High sensitivity differential scanning microcalorimetry (HSDSC), X-ray, Pulse 1H-NMR spectroscopy, and scanning electron microscopy (SEM) were used to analyse changes in the physico–chemical properties and microstructure of modified starches.High pressure-treated Hylon VII showed a slight degree of granules gelatinisation (GD = 10.8%). Whereas, “pressurised” waxy maize starch manifested complete disintegration of granules (GD = 85.9%) and formed a gel-like structure. The gelatinisation degree of “pressurised” starch mixtures decreased along with an increase in Hylon VII concentration. The starch preparations (650 MPa/9 min) after rehydration revealed low values of a swelling index and mobility of water molecules along with an increase in Hylon VII concentration. The high pressure-treated starches, with the exception of Hylon VII, manifested significant changes in their crystalline structure.